diff mbox series

[v8,2/2] x86: Update _dl_tlsdesc_dynamic to preserve caller-saved registers

Message ID 20240216151711.2742988-3-hjl.tools@gmail.com
State New
Headers show
Series x86: Update _dl_tlsdesc_dynamic to preserve caller-saved registers | expand

Commit Message

H.J. Lu Feb. 16, 2024, 3:17 p.m. UTC
Compiler generates the following instruction sequence for GNU2 dynamic
TLS access:

	leaq	tls_var@TLSDESC(%rip), %rax
	call	*tls_var@TLSCALL(%rax)

or

	leal	tls_var@TLSDESC(%ebx), %eax
	call	*tls_var@TLSCALL(%eax)

CALL instruction is transparent to compiler which assumes all registers,
except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
_dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
path.  __tls_get_addr is a normal function which doesn't preserve any
caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
caller-saved registers, but didn't preserve any other caller-saved
registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
XSAVE and XSAVEC to save and restore all caller-saved registers.  This
fixes BZ #31372.

Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
to optimize elf_machine_runtime_setup.
---
 elf/Makefile                                 |  14 ++
 elf/tst-gnu2-tls2.c                          | 120 ++++++++++++
 elf/tst-gnu2-tls2.h                          |  36 ++++
 elf/tst-gnu2-tls2mod0.c                      |  31 +++
 elf/tst-gnu2-tls2mod1.c                      |  31 +++
 elf/tst-gnu2-tls2mod2.c                      |  31 +++
 sysdeps/i386/dl-machine.h                    |   2 +-
 sysdeps/i386/dl-tlsdesc-dynamic.h            | 190 +++++++++++++++++++
 sysdeps/i386/dl-tlsdesc.S                    | 115 +++++------
 sysdeps/x86/Makefile                         |   7 +-
 sysdeps/x86/cpu-features.c                   |  56 +++++-
 sysdeps/x86/dl-procinfo.c                    |  16 ++
 sysdeps/{x86_64 => x86}/features-offsets.sym |   2 +
 sysdeps/x86/sysdep.h                         |   6 +
 sysdeps/x86/tst-gnu2-tls2.c                  |  20 ++
 sysdeps/x86_64/Makefile                      |   2 +-
 sysdeps/x86_64/dl-machine.h                  |  19 +-
 sysdeps/x86_64/dl-procinfo.c                 |  16 ++
 sysdeps/x86_64/dl-tlsdesc-dynamic.h          | 166 ++++++++++++++++
 sysdeps/x86_64/dl-tlsdesc.S                  | 108 ++++-------
 sysdeps/x86_64/dl-trampoline-save.h          |  34 ++++
 sysdeps/x86_64/dl-trampoline-state.h         |  51 +++++
 sysdeps/x86_64/dl-trampoline.S               |  20 +-
 sysdeps/x86_64/dl-trampoline.h               |  34 +---
 24 files changed, 914 insertions(+), 213 deletions(-)
 create mode 100644 elf/tst-gnu2-tls2.c
 create mode 100644 elf/tst-gnu2-tls2.h
 create mode 100644 elf/tst-gnu2-tls2mod0.c
 create mode 100644 elf/tst-gnu2-tls2mod1.c
 create mode 100644 elf/tst-gnu2-tls2mod2.c
 create mode 100644 sysdeps/i386/dl-tlsdesc-dynamic.h
 rename sysdeps/{x86_64 => x86}/features-offsets.sym (89%)
 create mode 100644 sysdeps/x86/tst-gnu2-tls2.c
 create mode 100644 sysdeps/x86_64/dl-tlsdesc-dynamic.h
 create mode 100644 sysdeps/x86_64/dl-trampoline-save.h
 create mode 100644 sysdeps/x86_64/dl-trampoline-state.h

Comments

Noah Goldstein Feb. 24, 2024, 5:09 p.m. UTC | #1
On Fri, Feb 16, 2024 at 9:17 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> Compiler generates the following instruction sequence for GNU2 dynamic
> TLS access:
>
>         leaq    tls_var@TLSDESC(%rip), %rax
>         call    *tls_var@TLSCALL(%rax)
>
> or
>
>         leal    tls_var@TLSDESC(%ebx), %eax
>         call    *tls_var@TLSCALL(%eax)
>
> CALL instruction is transparent to compiler which assumes all registers,
> except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
> _dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
> path.  __tls_get_addr is a normal function which doesn't preserve any
> caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
> caller-saved registers, but didn't preserve any other caller-saved
> registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
> XSAVE and XSAVEC to save and restore all caller-saved registers.  This
> fixes BZ #31372.
>
> Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
> to optimize elf_machine_runtime_setup.
> ---
>  elf/Makefile                                 |  14 ++
>  elf/tst-gnu2-tls2.c                          | 120 ++++++++++++
>  elf/tst-gnu2-tls2.h                          |  36 ++++
>  elf/tst-gnu2-tls2mod0.c                      |  31 +++
>  elf/tst-gnu2-tls2mod1.c                      |  31 +++
>  elf/tst-gnu2-tls2mod2.c                      |  31 +++
>  sysdeps/i386/dl-machine.h                    |   2 +-
>  sysdeps/i386/dl-tlsdesc-dynamic.h            | 190 +++++++++++++++++++
>  sysdeps/i386/dl-tlsdesc.S                    | 115 +++++------
>  sysdeps/x86/Makefile                         |   7 +-
>  sysdeps/x86/cpu-features.c                   |  56 +++++-
>  sysdeps/x86/dl-procinfo.c                    |  16 ++
>  sysdeps/{x86_64 => x86}/features-offsets.sym |   2 +
>  sysdeps/x86/sysdep.h                         |   6 +
>  sysdeps/x86/tst-gnu2-tls2.c                  |  20 ++
>  sysdeps/x86_64/Makefile                      |   2 +-
>  sysdeps/x86_64/dl-machine.h                  |  19 +-
>  sysdeps/x86_64/dl-procinfo.c                 |  16 ++
>  sysdeps/x86_64/dl-tlsdesc-dynamic.h          | 166 ++++++++++++++++
>  sysdeps/x86_64/dl-tlsdesc.S                  | 108 ++++-------
>  sysdeps/x86_64/dl-trampoline-save.h          |  34 ++++
>  sysdeps/x86_64/dl-trampoline-state.h         |  51 +++++
>  sysdeps/x86_64/dl-trampoline.S               |  20 +-
>  sysdeps/x86_64/dl-trampoline.h               |  34 +---
>  24 files changed, 914 insertions(+), 213 deletions(-)
>  create mode 100644 elf/tst-gnu2-tls2.c
>  create mode 100644 elf/tst-gnu2-tls2.h
>  create mode 100644 elf/tst-gnu2-tls2mod0.c
>  create mode 100644 elf/tst-gnu2-tls2mod1.c
>  create mode 100644 elf/tst-gnu2-tls2mod2.c
>  create mode 100644 sysdeps/i386/dl-tlsdesc-dynamic.h
>  rename sysdeps/{x86_64 => x86}/features-offsets.sym (89%)
>  create mode 100644 sysdeps/x86/tst-gnu2-tls2.c
>  create mode 100644 sysdeps/x86_64/dl-tlsdesc-dynamic.h
>  create mode 100644 sysdeps/x86_64/dl-trampoline-save.h
>  create mode 100644 sysdeps/x86_64/dl-trampoline-state.h
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 5d78b659ce..030db4d207 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -424,6 +424,7 @@ tests += \
>    tst-glibc-hwcaps-prepend \
>    tst-global1 \
>    tst-global2 \
> +  tst-gnu2-tls2 \
>    tst-initfinilazyfail \
>    tst-initorder \
>    tst-initorder2 \
> @@ -846,6 +847,9 @@ modules-names += \
>    tst-filterobj-flt \
>    tst-finilazyfailmod \
>    tst-globalmod2 \
> +  tst-gnu2-tls2mod0 \
> +  tst-gnu2-tls2mod1 \
> +  tst-gnu2-tls2mod2 \
>    tst-initlazyfailmod \
>    tst-initorder2a \
>    tst-initorder2b \
> @@ -3044,8 +3048,18 @@ $(objpfx)tst-tlsgap.out: \
>    $(objpfx)tst-tlsgap-mod0.so \
>    $(objpfx)tst-tlsgap-mod1.so \
>    $(objpfx)tst-tlsgap-mod2.so
> +
> +$(objpfx)tst-gnu2-tls2: $(shared-thread-library)
> +$(objpfx)tst-gnu2-tls2.out: \
> +  $(objpfx)tst-gnu2-tls2mod0.so \
> +  $(objpfx)tst-gnu2-tls2mod1.so \
> +  $(objpfx)tst-gnu2-tls2mod2.so
> +
>  ifeq (yes,$(have-mtls-dialect-gnu2))
>  CFLAGS-tst-tlsgap-mod0.c += -mtls-dialect=gnu2
>  CFLAGS-tst-tlsgap-mod1.c += -mtls-dialect=gnu2
>  CFLAGS-tst-tlsgap-mod2.c += -mtls-dialect=gnu2
> +CFLAGS-tst-gnu2-tls2mod0.c += -mtls-dialect=gnu2
> +CFLAGS-tst-gnu2-tls2mod1.c += -mtls-dialect=gnu2
> +CFLAGS-tst-gnu2-tls2mod2.c += -mtls-dialect=gnu2
>  endif
> diff --git a/elf/tst-gnu2-tls2.c b/elf/tst-gnu2-tls2.c
> new file mode 100644
> index 0000000000..8039ba614d
> --- /dev/null
> +++ b/elf/tst-gnu2-tls2.c
> @@ -0,0 +1,120 @@
> +/* Test TLSDESC relocation.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <dlfcn.h>
> +#include <pthread.h>
> +#include <support/xdlfcn.h>
> +#include <support/xthread.h>
> +#include <support/check.h>
> +#include <support/test-driver.h>
> +#include "tst-gnu2-tls2.h"
> +
> +#ifndef IS_SUPPORTED
> +# define IS_SUPPORTED() true
> +#endif
> +
> +/* An architecture can define it to clobber caller-saved registers in
> +   malloc below to verify that the implicit TLSDESC call won't change
> +   caller-saved registers.  */
> +#ifndef PREPARE_MALLOC
> +# define PREPARE_MALLOC()
> +#endif
> +
> +extern void * __libc_malloc (size_t);
> +
> +size_t malloc_counter = 0;
> +
> +void *
> +malloc (size_t n)
> +{
> +  PREPARE_MALLOC ();
> +  malloc_counter++;
> +  return __libc_malloc (n);
> +}
> +
> +static void *mod[3];
> +#define MOD(i) "tst-gnu2-tls2mod" #i ".so"
> +static const char *modname[3] = { MOD(0), MOD(1), MOD(2) };
> +#undef MOD
> +
> +static void
> +open_mod (int i)
> +{
> +  mod[i] = xdlopen (modname[i], RTLD_LAZY);
> +  printf ("open %s\n", modname[i]);
> +}
> +
> +static void
> +close_mod (int i)
> +{
> +  xdlclose (mod[i]);
> +  mod[i] = NULL;
> +  printf ("close %s\n", modname[i]);
> +}
> +
> +static void
> +access_mod (int i, const char *sym)
> +{
> +  struct tls var = { -1, -1, -1, -1 };
> +  struct tls *(*f) (struct tls *) = xdlsym (mod[i], sym);
> +  /* Check that our malloc is called.  */
> +  malloc_counter = 0;
> +  struct tls *p = f (&var);
> +  TEST_VERIFY (malloc_counter != 0);
> +  printf ("access %s: %s() = %p\n", modname[i], sym, p);
> +  TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
> +  ++(p->a);
> +}
> +
> +static void *
> +start (void *arg)
> +{
> +  /* The DTV generation is at the last dlopen of mod0 and the
> +     entry for mod1 is NULL.  */
> +
> +  open_mod (1); /* Reuse modid of mod1. Uses dynamic TLS.  */
> +
> +  /* Force the slow path in GNU2 TLS descriptor call.  */
> +  access_mod (1, "apply_tls");
> +
> +  return arg;
> +}
> +
> +static int
> +do_test (void)
> +{
> +  if (!IS_SUPPORTED ())
> +    return EXIT_UNSUPPORTED;
> +
> +  open_mod (0);
> +  open_mod (1);
> +  open_mod (2);
> +  close_mod (0);
> +  close_mod (1); /* Create modid gap at mod1.  */
> +  open_mod (0); /* Reuse modid of mod0, bump generation count.  */
> +
> +  /* Create a thread where DTV of mod1 is NULL.  */
> +  pthread_t t = xpthread_create (NULL, start, NULL);
> +  xpthread_join (t);
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>

The change looks good but this is still failing on arm.

```
FAIL: elf/tst-gnu2-tls2
original exit status 1
open tst-gnu2-tls2mod0.so
open tst-gnu2-tls2mod1.so
open tst-gnu2-tls2mod2.so
close tst-gnu2-tls2mod0.so
close tst-gnu2-tls2mod1.so
open tst-gnu2-tls2mod0.so
open tst-gnu2-tls2mod1.so
Didn't expect signal from child: got `Segmentation fault'
```

HJ can you add some more logging to its clear exactly where
the fault is? (looks to be malloc or xdlsym).

Are there any other arch this is failing on? I.e is this an arm
bug or buggy test?


> diff --git a/elf/tst-gnu2-tls2.h b/elf/tst-gnu2-tls2.h
> new file mode 100644
> index 0000000000..77964a57a3
> --- /dev/null
> +++ b/elf/tst-gnu2-tls2.h
> @@ -0,0 +1,36 @@
> +/* Test TLSDESC relocation.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <stdint.h>
> +
> +struct tls
> +{
> +  int64_t a, b, c, d;
> +};
> +
> +extern struct tls *apply_tls (struct tls *);
> +
> +/* An architecture can define them to verify that clobber caller-saved
> +   registers aren't changed by the implicit TLSDESC call.  */
> +#ifndef BEFORE_TLSDESC_CALL
> +# define BEFORE_TLSDESC_CALL()
> +#endif
> +
> +#ifndef AFTER_TLSDESC_CALL
> +# define AFTER_TLSDESC_CALL()
> +#endif
> diff --git a/elf/tst-gnu2-tls2mod0.c b/elf/tst-gnu2-tls2mod0.c
> new file mode 100644
> index 0000000000..20f177244d
> --- /dev/null
> +++ b/elf/tst-gnu2-tls2mod0.c
> @@ -0,0 +1,31 @@
> +/* DSO used by tst-gnu2-tls2.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include "tst-gnu2-tls2.h"
> +
> +__thread struct tls tls_var0 __attribute__ ((visibility ("hidden")));
> +
> +struct tls *
> +apply_tls (struct tls *p)
> +{
> +  tls_var0 = *p;
> +  BEFORE_TLSDESC_CALL ();
> +  struct tls *ret = &tls_var0;
> +  AFTER_TLSDESC_CALL ();
> +  return ret;
> +}
> diff --git a/elf/tst-gnu2-tls2mod1.c b/elf/tst-gnu2-tls2mod1.c
> new file mode 100644
> index 0000000000..86a6ee48f7
> --- /dev/null
> +++ b/elf/tst-gnu2-tls2mod1.c
> @@ -0,0 +1,31 @@
> +/* DSO used by tst-gnu2-tls2.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include "tst-gnu2-tls2.h"
> +
> +__thread struct tls tls_var1[100] __attribute__ ((visibility ("hidden")));
> +
> +struct tls *
> +apply_tls (struct tls *p)
> +{
> +  tls_var1[1] = *p;
> +  BEFORE_TLSDESC_CALL ();
> +  struct tls *ret = &tls_var1[1];
> +  AFTER_TLSDESC_CALL ();
> +  return ret;
> +}
> diff --git a/elf/tst-gnu2-tls2mod2.c b/elf/tst-gnu2-tls2mod2.c
> new file mode 100644
> index 0000000000..dede07599b
> --- /dev/null
> +++ b/elf/tst-gnu2-tls2mod2.c
> @@ -0,0 +1,31 @@
> +/* DSO used by tst-gnu2-tls2.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include "tst-gnu2-tls2.h"
> +
> +__thread struct tls tls_var2 __attribute__ ((visibility ("hidden")));
> +
> +struct tls *
> +apply_tls (struct tls *p)
> +{
> +  tls_var2 = *p;
> +  BEFORE_TLSDESC_CALL ();
> +  struct tls *ret = &tls_var2;
> +  AFTER_TLSDESC_CALL ();
> +  return ret;
> +}
> diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
> index fc1ef96587..50d74fe6e9 100644
> --- a/sysdeps/i386/dl-machine.h
> +++ b/sysdeps/i386/dl-machine.h
> @@ -347,7 +347,7 @@ and creates an unsatisfiable circular dependency.\n",
>                   {
>                     td->arg = _dl_make_tlsdesc_dynamic
>                       (sym_map, sym->st_value + (ElfW(Word))td->arg);
> -                   td->entry = _dl_tlsdesc_dynamic;
> +                   td->entry = GLRO(dl_x86_tlsdesc_dynamic);
>                   }
>                 else
>  #  endif
> diff --git a/sysdeps/i386/dl-tlsdesc-dynamic.h b/sysdeps/i386/dl-tlsdesc-dynamic.h
> new file mode 100644
> index 0000000000..3627028577
> --- /dev/null
> +++ b/sysdeps/i386/dl-tlsdesc-dynamic.h
> @@ -0,0 +1,190 @@
> +/* Thread-local storage handling in the ELF dynamic linker.  i386 version.
> +   Copyright (C) 2004-2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#undef REGISTER_SAVE_AREA
> +
> +#if !defined USE_FNSAVE && (STATE_SAVE_ALIGNMENT % 16) != 0
> +# error STATE_SAVE_ALIGNMENT must be multiple of 16
> +#endif
> +
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +# ifdef USE_FNSAVE
> +#  error USE_FNSAVE shouldn't be defined
> +# endif
> +# ifdef USE_FXSAVE
> +/* Use fxsave to save all registers.  */
> +#  define REGISTER_SAVE_AREA   512
> +# endif
> +#else
> +# ifdef USE_FNSAVE
> +/* Use fnsave to save x87 FPU stack registers.  */
> +#  define REGISTER_SAVE_AREA   108
> +# else
> +#  ifndef USE_FXSAVE
> +#   error USE_FXSAVE must be defined
> +#  endif
> +/* Use fxsave to save all registers.  Add 12 bytes to align the stack
> +   to 16 bytes.  */
> +#  define REGISTER_SAVE_AREA   (512 + 12)
> +# endif
> +#endif
> +
> +       .hidden _dl_tlsdesc_dynamic
> +       .global _dl_tlsdesc_dynamic
> +       .type   _dl_tlsdesc_dynamic,@function
> +
> +     /* This function is used for symbols that need dynamic TLS.
> +
> +       %eax points to the TLS descriptor, such that 0(%eax) points to
> +       _dl_tlsdesc_dynamic itself, and 4(%eax) points to a struct
> +       tlsdesc_dynamic_arg object.  It must return in %eax the offset
> +       between the thread pointer and the object denoted by the
> +       argument, without clobbering any registers.
> +
> +       The assembly code that follows is a rendition of the following
> +       C code, hand-optimized a little bit.
> +
> +ptrdiff_t
> +__attribute__ ((__regparm__ (1)))
> +_dl_tlsdesc_dynamic (struct tlsdesc *tdp)
> +{
> +  struct tlsdesc_dynamic_arg *td = tdp->arg;
> +  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> +  if (__builtin_expect (td->gen_count <= dtv[0].counter
> +                       && (dtv[td->tlsinfo.ti_module].pointer.val
> +                           != TLS_DTV_UNALLOCATED),
> +                       1))
> +    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> +      - __thread_pointer;
> +
> +  return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
> +}
> +*/
> +       cfi_startproc
> +       .align 16
> +_dl_tlsdesc_dynamic:
> +       /* Like all TLS resolvers, preserve call-clobbered registers.
> +          We need two scratch regs anyway.  */
> +       subl    $32, %esp
> +       cfi_adjust_cfa_offset (32)
> +       movl    %ecx, 20(%esp)
> +       movl    %edx, 24(%esp)
> +       movl    TLSDESC_ARG(%eax), %eax
> +       movl    %gs:DTV_OFFSET, %edx
> +       movl    TLSDESC_GEN_COUNT(%eax), %ecx
> +       cmpl    (%edx), %ecx
> +       ja      2f
> +       movl    TLSDESC_MODID(%eax), %ecx
> +       movl    (%edx,%ecx,8), %edx
> +       cmpl    $-1, %edx
> +       je      2f
> +       movl    TLSDESC_MODOFF(%eax), %eax
> +       addl    %edx, %eax
> +1:
> +       movl    20(%esp), %ecx
> +       subl    %gs:0, %eax
> +       movl    24(%esp), %edx
> +       addl    $32, %esp
> +       cfi_adjust_cfa_offset (-32)
> +       ret
> +       .p2align 4,,7
> +2:
> +       cfi_adjust_cfa_offset (32)
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       movl    %ebx, -28(%esp)
> +       movl    %esp, %ebx
> +       cfi_def_cfa_register(%ebx)
> +       and     $-STATE_SAVE_ALIGNMENT, %esp
> +#endif
> +#ifdef REGISTER_SAVE_AREA
> +       subl    $REGISTER_SAVE_AREA, %esp
> +# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
> +# endif
> +#else
> +# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
> +#  error DL_RUNTIME_RESOLVE_REALIGN_STACK must be true
> +# endif
> +       /* Allocate stack space of the required size to save the state.  */
> +       LOAD_PIC_REG (cx)
> +       subl    RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_SIZE_OFFSET+_rtld_local_ro@GOTOFF(%ecx), %esp
> +#endif
> +#ifdef USE_FNSAVE
> +       fnsave  (%esp)
> +#elif defined USE_FXSAVE
> +       fxsave  (%esp)
> +#else
> +       /* Save the argument for ___tls_get_addr in EAX.  */
> +       movl    %eax, %ecx
> +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> +       xorl    %edx, %edx
> +       /* Clear the XSAVE Header.  */
> +# ifdef USE_XSAVE
> +       movl    %edx, (512)(%esp)
> +       movl    %edx, (512 + 4 * 1)(%esp)
> +       movl    %edx, (512 + 4 * 2)(%esp)
> +       movl    %edx, (512 + 4 * 3)(%esp)
> +# endif
> +       movl    %edx, (512 + 4 * 4)(%esp)
> +       movl    %edx, (512 + 4 * 5)(%esp)
> +       movl    %edx, (512 + 4 * 6)(%esp)
> +       movl    %edx, (512 + 4 * 7)(%esp)
> +       movl    %edx, (512 + 4 * 8)(%esp)
> +       movl    %edx, (512 + 4 * 9)(%esp)
> +       movl    %edx, (512 + 4 * 10)(%esp)
> +       movl    %edx, (512 + 4 * 11)(%esp)
> +       movl    %edx, (512 + 4 * 12)(%esp)
> +       movl    %edx, (512 + 4 * 13)(%esp)
> +       movl    %edx, (512 + 4 * 14)(%esp)
> +       movl    %edx, (512 + 4 * 15)(%esp)
> +# ifdef USE_XSAVE
> +       xsave   (%esp)
> +# else
> +       xsavec  (%esp)
> +# endif
> +       /* Restore the argument for ___tls_get_addr in EAX.  */
> +       movl    %ecx, %eax
> +#endif
> +       call    HIDDEN_JUMPTARGET (___tls_get_addr)
> +       /* Get register content back.  */
> +#ifdef USE_FNSAVE
> +       frstor  (%esp)
> +#elif defined USE_FXSAVE
> +       fxrstor (%esp)
> +#else
> +       /* Save and retore ___tls_get_addr return value stored in EAX.  */
> +       movl    %eax, %ecx
> +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> +       xorl    %edx, %edx
> +       xrstor  (%esp)
> +       movl    %ecx, %eax
> +#endif
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       mov     %ebx, %esp
> +       cfi_def_cfa_register(%esp)
> +       movl    -28(%esp), %ebx
> +       cfi_restore(%ebx)
> +#else
> +       addl    $REGISTER_SAVE_AREA, %esp
> +       cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
> +#endif
> +       jmp     1b
> +       cfi_endproc
> +       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> +
> +#undef STATE_SAVE_ALIGNMENT
> diff --git a/sysdeps/i386/dl-tlsdesc.S b/sysdeps/i386/dl-tlsdesc.S
> index 90d93caa0c..f002feee56 100644
> --- a/sysdeps/i386/dl-tlsdesc.S
> +++ b/sysdeps/i386/dl-tlsdesc.S
> @@ -18,8 +18,27 @@
>
>  #include <sysdep.h>
>  #include <tls.h>
> +#include <cpu-features-offsets.h>
> +#include <features-offsets.h>
>  #include "tlsdesc.h"
>
> +#ifndef DL_STACK_ALIGNMENT
> +/* Due to GCC bug:
> +
> +   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> +
> +   __tls_get_addr may be called with 4-byte stack alignment.  Although
> +   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
> +   that stack will be always aligned at 16 bytes.  */
> +# define DL_STACK_ALIGNMENT 4
> +#endif
> +
> +/* True if _dl_tlsdesc_dynamic should align stack for STATE_SAVE or align
> +   stack to MINIMUM_ALIGNMENT bytes before calling ___tls_get_addr.  */
> +#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> +  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> +   || MINIMUM_ALIGNMENT > DL_STACK_ALIGNMENT)
> +
>         .text
>
>       /* This function is used to compute the TP offset for symbols in
> @@ -65,69 +84,35 @@ _dl_tlsdesc_undefweak:
>         .size   _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
>
>  #ifdef SHARED
> -       .hidden _dl_tlsdesc_dynamic
> -       .global _dl_tlsdesc_dynamic
> -       .type   _dl_tlsdesc_dynamic,@function
> -
> -     /* This function is used for symbols that need dynamic TLS.
> -
> -       %eax points to the TLS descriptor, such that 0(%eax) points to
> -       _dl_tlsdesc_dynamic itself, and 4(%eax) points to a struct
> -       tlsdesc_dynamic_arg object.  It must return in %eax the offset
> -       between the thread pointer and the object denoted by the
> -       argument, without clobbering any registers.
> -
> -       The assembly code that follows is a rendition of the following
> -       C code, hand-optimized a little bit.
> -
> -ptrdiff_t
> -__attribute__ ((__regparm__ (1)))
> -_dl_tlsdesc_dynamic (struct tlsdesc *tdp)
> -{
> -  struct tlsdesc_dynamic_arg *td = tdp->arg;
> -  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> -  if (__builtin_expect (td->gen_count <= dtv[0].counter
> -                       && (dtv[td->tlsinfo.ti_module].pointer.val
> -                           != TLS_DTV_UNALLOCATED),
> -                       1))
> -    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> -      - __thread_pointer;
> -
> -  return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
> -}
> -*/
> -       cfi_startproc
> -       .align 16
> -_dl_tlsdesc_dynamic:
> -       /* Like all TLS resolvers, preserve call-clobbered registers.
> -          We need two scratch regs anyway.  */
> -       subl    $28, %esp
> -       cfi_adjust_cfa_offset (28)
> -       movl    %ecx, 20(%esp)
> -       movl    %edx, 24(%esp)
> -       movl    TLSDESC_ARG(%eax), %eax
> -       movl    %gs:DTV_OFFSET, %edx
> -       movl    TLSDESC_GEN_COUNT(%eax), %ecx
> -       cmpl    (%edx), %ecx
> -       ja      .Lslow
> -       movl    TLSDESC_MODID(%eax), %ecx
> -       movl    (%edx,%ecx,8), %edx
> -       cmpl    $-1, %edx
> -       je      .Lslow
> -       movl    TLSDESC_MODOFF(%eax), %eax
> -       addl    %edx, %eax
> -.Lret:
> -       movl    20(%esp), %ecx
> -       subl    %gs:0, %eax
> -       movl    24(%esp), %edx
> -       addl    $28, %esp
> -       cfi_adjust_cfa_offset (-28)
> -       ret
> -       .p2align 4,,7
> -.Lslow:
> -       cfi_adjust_cfa_offset (28)
> -       call    HIDDEN_JUMPTARGET (___tls_get_addr)
> -       jmp     .Lret
> -       cfi_endproc
> -       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> +# define USE_FNSAVE
> +# define MINIMUM_ALIGNMENT     4
> +# define STATE_SAVE_ALIGNMENT  4
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_fnsave
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef MINIMUM_ALIGNMENT
> +# undef USE_FNSAVE
> +
> +# define MINIMUM_ALIGNMENT     16
> +
> +# define USE_FXSAVE
> +# define STATE_SAVE_ALIGNMENT  16
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_fxsave
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_FXSAVE
> +
> +# define USE_XSAVE
> +# define STATE_SAVE_ALIGNMENT  64
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsave
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_XSAVE
> +
> +# define USE_XSAVEC
> +# define STATE_SAVE_ALIGNMENT  64
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsavec
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_XSAVEC
>  #endif /* SHARED */
> diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
> index 73b29cc78c..5311b594af 100644
> --- a/sysdeps/x86/Makefile
> +++ b/sysdeps/x86/Makefile
> @@ -1,5 +1,5 @@
>  ifeq ($(subdir),csu)
> -gen-as-const-headers += cpu-features-offsets.sym
> +gen-as-const-headers += cpu-features-offsets.sym features-offsets.sym
>  endif
>
>  ifeq ($(subdir),elf)
> @@ -86,6 +86,11 @@ endif
>  tst-ifunc-isa-2-ENV = GLIBC_TUNABLES=glibc.cpu.hwcaps=-SSE4_2,-AVX,-AVX2,-AVX512F
>  tst-ifunc-isa-2-static-ENV = $(tst-ifunc-isa-2-ENV)
>  tst-hwcap-tunables-ARGS = -- $(host-test-program-cmd)
> +
> +CFLAGS-tst-gnu2-tls2.c += -msse
> +CFLAGS-tst-gnu2-tls2mod0.c += -msse2 -mtune=haswell
> +CFLAGS-tst-gnu2-tls2mod1.c += -msse2 -mtune=haswell
> +CFLAGS-tst-gnu2-tls2mod2.c += -msse2 -mtune=haswell
>  endif
>
>  ifeq ($(subdir),math)
> diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> index 25e6622a79..835113b42f 100644
> --- a/sysdeps/x86/cpu-features.c
> +++ b/sysdeps/x86/cpu-features.c
> @@ -27,8 +27,13 @@
>  extern void TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *)
>    attribute_hidden;
>
> -#if defined SHARED && defined __x86_64__
> -# include <dl-plt-rewrite.h>
> +#if defined SHARED
> +extern void _dl_tlsdesc_dynamic_fxsave (void) attribute_hidden;
> +extern void _dl_tlsdesc_dynamic_xsave (void) attribute_hidden;
> +extern void _dl_tlsdesc_dynamic_xsavec (void) attribute_hidden;
> +
> +# ifdef __x86_64__
> +#  include <dl-plt-rewrite.h>
>
>  static void
>  TUNABLE_CALLBACK (set_plt_rewrite) (tunable_val_t *valp)
> @@ -47,6 +52,15 @@ TUNABLE_CALLBACK (set_plt_rewrite) (tunable_val_t *valp)
>                  : plt_rewrite_jmp);
>      }
>  }
> +# else
> +extern void _dl_tlsdesc_dynamic_fnsave (void) attribute_hidden;
> +# endif
> +#endif
> +
> +#ifdef __x86_64__
> +extern void _dl_runtime_resolve_fxsave (void) attribute_hidden;
> +extern void _dl_runtime_resolve_xsave (void) attribute_hidden;
> +extern void _dl_runtime_resolve_xsavec (void) attribute_hidden;
>  #endif
>
>  #ifdef __LP64__
> @@ -1130,6 +1144,44 @@ no_cpuid:
>                TUNABLE_CALLBACK (set_x86_shstk));
>  #endif
>
> +  if (GLRO(dl_x86_cpu_features).xsave_state_size != 0)
> +    {
> +      if (CPU_FEATURE_USABLE_P (cpu_features, XSAVEC))
> +       {
> +#ifdef __x86_64__
> +         GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_xsavec;
> +#endif
> +#ifdef SHARED
> +         GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_xsavec;
> +#endif
> +       }
> +      else
> +       {
> +#ifdef __x86_64__
> +         GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_xsave;
> +#endif
> +#ifdef SHARED
> +         GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_xsave;
> +#endif
> +       }
> +    }
> +  else
> +    {
> +#ifdef __x86_64__
> +      GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_fxsave;
> +# ifdef SHARED
> +      GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fxsave;
> +# endif
> +#else
> +# ifdef SHARED
> +      if (CPU_FEATURE_USABLE_P (cpu_features, FXSR))
> +       GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fxsave;
> +      else
> +       GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fnsave;
> +# endif
> +#endif
> +    }
> +
>  #ifdef SHARED
>  # ifdef __x86_64__
>    TUNABLE_GET (plt_rewrite, tunable_val_t *,
> diff --git a/sysdeps/x86/dl-procinfo.c b/sysdeps/x86/dl-procinfo.c
> index ee957b4d70..5920d4b320 100644
> --- a/sysdeps/x86/dl-procinfo.c
> +++ b/sysdeps/x86/dl-procinfo.c
> @@ -86,3 +86,19 @@ PROCINFO_CLASS const char _dl_x86_platforms[4][9]
>  #else
>  ,
>  #endif
> +
> +#if defined SHARED && !IS_IN (ldconfig)
> +# if !defined PROCINFO_DECL
> +  ._dl_x86_tlsdesc_dynamic
> +# else
> +PROCINFO_CLASS void * _dl_x86_tlsdesc_dynamic
> +# endif
> +# ifndef PROCINFO_DECL
> += NULL
> +# endif
> +# ifdef PROCINFO_DECL
> +;
> +# else
> +,
> +# endif
> +#endif
> diff --git a/sysdeps/x86_64/features-offsets.sym b/sysdeps/x86/features-offsets.sym
> similarity index 89%
> rename from sysdeps/x86_64/features-offsets.sym
> rename to sysdeps/x86/features-offsets.sym
> index 9e4be3393a..77e990c705 100644
> --- a/sysdeps/x86_64/features-offsets.sym
> +++ b/sysdeps/x86/features-offsets.sym
> @@ -3,4 +3,6 @@
>  #include <ldsodefs.h>
>
>  RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET offsetof (struct rtld_global_ro, _dl_x86_cpu_features)
> +#ifdef __x86_64__
>  RTLD_GLOBAL_DL_X86_FEATURE_1_OFFSET offsetof (struct rtld_global, _dl_x86_feature_1)
> +#endif
> diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
> index 837fd28734..485cad9c02 100644
> --- a/sysdeps/x86/sysdep.h
> +++ b/sysdeps/x86/sysdep.h
> @@ -70,6 +70,12 @@
>     | (1 << X86_XSTATE_ZMM_H_ID))
>  #endif
>
> +/* States which should be saved for TLSDESC_CALL and TLS_DESC_CALL.
> +   Compiler assumes that all registers, including x87 FPU stack registers,
> +   are unchanged after CALL, except for EFLAGS and RAX/EAX.  */
> +#define TLSDESC_CALL_STATE_SAVE_MASK   \
> +  (STATE_SAVE_MASK | (1 << X86_XSTATE_X87_ID))
> +
>  /* Constants for bits in __x86_string_control:  */
>
>  /* Avoid short distance REP MOVSB.  */
> diff --git a/sysdeps/x86/tst-gnu2-tls2.c b/sysdeps/x86/tst-gnu2-tls2.c
> new file mode 100644
> index 0000000000..de900a423b
> --- /dev/null
> +++ b/sysdeps/x86/tst-gnu2-tls2.c
> @@ -0,0 +1,20 @@
> +#ifndef __x86_64__
> +#include <sys/platform/x86.h>
> +
> +#define IS_SUPPORTED() CPU_FEATURE_ACTIVE (SSE2)
> +#endif
> +
> +/* Clear XMM0...XMM7  */
> +#define PREPARE_MALLOC()                               \
> +{                                                      \
> +  asm volatile ("xorps %%xmm0, %%xmm0" : : : "xmm0" ); \
> +  asm volatile ("xorps %%xmm1, %%xmm1" : : : "xmm1" ); \
> +  asm volatile ("xorps %%xmm2, %%xmm2" : : : "xmm2" ); \
> +  asm volatile ("xorps %%xmm3, %%xmm3" : : : "xmm3" ); \
> +  asm volatile ("xorps %%xmm4, %%xmm4" : : : "xmm4" ); \
> +  asm volatile ("xorps %%xmm5, %%xmm5" : : : "xmm5" ); \
> +  asm volatile ("xorps %%xmm6, %%xmm6" : : : "xmm6" ); \
> +  asm volatile ("xorps %%xmm7, %%xmm7" : : : "xmm7" ); \
> +}
> +
> +#include <elf/tst-gnu2-tls2.c>
> diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile
> index 145f25e7f6..9337e95093 100644
> --- a/sysdeps/x86_64/Makefile
> +++ b/sysdeps/x86_64/Makefile
> @@ -10,7 +10,7 @@ LDFLAGS-rtld += -Wl,-z,nomark-plt
>  endif
>
>  ifeq ($(subdir),csu)
> -gen-as-const-headers += features-offsets.sym link-defines.sym
> +gen-as-const-headers += link-defines.sym
>  endif
>
>  ifeq ($(subdir),gmon)
> diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
> index 6d605d0d32..ff5d45f7cb 100644
> --- a/sysdeps/x86_64/dl-machine.h
> +++ b/sysdeps/x86_64/dl-machine.h
> @@ -71,9 +71,6 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
>                            int lazy, int profile)
>  {
>    Elf64_Addr *got;
> -  extern void _dl_runtime_resolve_fxsave (ElfW(Word)) attribute_hidden;
> -  extern void _dl_runtime_resolve_xsave (ElfW(Word)) attribute_hidden;
> -  extern void _dl_runtime_resolve_xsavec (ElfW(Word)) attribute_hidden;
>    extern void _dl_runtime_profile_sse (ElfW(Word)) attribute_hidden;
>    extern void _dl_runtime_profile_avx (ElfW(Word)) attribute_hidden;
>    extern void _dl_runtime_profile_avx512 (ElfW(Word)) attribute_hidden;
> @@ -96,8 +93,6 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
>        /* Identify this shared object.  */
>        *(ElfW(Addr) *) (got + 1) = (ElfW(Addr)) l;
>
> -      const struct cpu_features* cpu_features = __get_cpu_features ();
> -
>  #ifdef SHARED
>        /* The got[2] entry contains the address of a function which gets
>          called to get the address of a so far unresolved function and
> @@ -107,6 +102,7 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
>          end in this function.  */
>        if (__glibc_unlikely (profile))
>         {
> +         const struct cpu_features* cpu_features = __get_cpu_features ();
>           if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512F))
>             *(ElfW(Addr) *) (got + 2) = (ElfW(Addr)) &_dl_runtime_profile_avx512;
>           else if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX))
> @@ -126,15 +122,8 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
>           /* This function will get called to fix up the GOT entry
>              indicated by the offset on the stack, and then jump to
>              the resolved address.  */
> -         if (MINIMUM_X86_ISA_LEVEL >= AVX_X86_ISA_LEVEL
> -             || GLRO(dl_x86_cpu_features).xsave_state_size != 0)
> -           *(ElfW(Addr) *) (got + 2)
> -             = (CPU_FEATURE_USABLE_P (cpu_features, XSAVEC)
> -                ? (ElfW(Addr)) &_dl_runtime_resolve_xsavec
> -                : (ElfW(Addr)) &_dl_runtime_resolve_xsave);
> -         else
> -           *(ElfW(Addr) *) (got + 2)
> -             = (ElfW(Addr)) &_dl_runtime_resolve_fxsave;
> +         *(ElfW(Addr) *) (got + 2)
> +           = (ElfW(Addr)) GLRO(dl_x86_64_runtime_resolve);
>         }
>      }
>
> @@ -383,7 +372,7 @@ and creates an unsatisfiable circular dependency.\n",
>                   {
>                     td->arg = _dl_make_tlsdesc_dynamic
>                       (sym_map, sym->st_value + reloc->r_addend);
> -                   td->entry = _dl_tlsdesc_dynamic;
> +                   td->entry = GLRO(dl_x86_tlsdesc_dynamic);
>                   }
>                 else
>  #  endif
> diff --git a/sysdeps/x86_64/dl-procinfo.c b/sysdeps/x86_64/dl-procinfo.c
> index 4d1d790fbb..06637a8154 100644
> --- a/sysdeps/x86_64/dl-procinfo.c
> +++ b/sysdeps/x86_64/dl-procinfo.c
> @@ -41,5 +41,21 @@
>
>  #include <sysdeps/x86/dl-procinfo.c>
>
> +#if !IS_IN (ldconfig)
> +# if !defined PROCINFO_DECL && defined SHARED
> +  ._dl_x86_64_runtime_resolve
> +# else
> +PROCINFO_CLASS void * _dl_x86_64_runtime_resolve
> +# endif
> +# ifndef PROCINFO_DECL
> += NULL
> +# endif
> +# if !defined SHARED || defined PROCINFO_DECL
> +;
> +# else
> +,
> +# endif
> +#endif
> +
>  #undef PROCINFO_DECL
>  #undef PROCINFO_CLASS
> diff --git a/sysdeps/x86_64/dl-tlsdesc-dynamic.h b/sysdeps/x86_64/dl-tlsdesc-dynamic.h
> new file mode 100644
> index 0000000000..0c2e8d5320
> --- /dev/null
> +++ b/sysdeps/x86_64/dl-tlsdesc-dynamic.h
> @@ -0,0 +1,166 @@
> +/* Thread-local storage handling in the ELF dynamic linker.  x86_64 version.
> +   Copyright (C) 2004-2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef SECTION
> +# define SECTION(p)    p
> +#endif
> +
> +#undef REGISTER_SAVE_AREA
> +#undef LOCAL_STORAGE_AREA
> +#undef BASE
> +
> +#include "dl-trampoline-state.h"
> +
> +       .section SECTION(.text),"ax",@progbits
> +
> +       .hidden _dl_tlsdesc_dynamic
> +       .global _dl_tlsdesc_dynamic
> +       .type   _dl_tlsdesc_dynamic,@function
> +
> +     /* %rax points to the TLS descriptor, such that 0(%rax) points to
> +       _dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct
> +       tlsdesc_dynamic_arg object.  It must return in %rax the offset
> +       between the thread pointer and the object denoted by the
> +       argument, without clobbering any registers.
> +
> +       The assembly code that follows is a rendition of the following
> +       C code, hand-optimized a little bit.
> +
> +ptrdiff_t
> +_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax"))
> +{
> +  struct tlsdesc_dynamic_arg *td = tdp->arg;
> +  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> +  if (__builtin_expect (td->gen_count <= dtv[0].counter
> +                       && (dtv[td->tlsinfo.ti_module].pointer.val
> +                           != TLS_DTV_UNALLOCATED),
> +                       1))
> +    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> +      - __thread_pointer;
> +
> +  return __tls_get_addr_internal (&td->tlsinfo) - __thread_pointer;
> +}
> +*/
> +       cfi_startproc
> +       .align 16
> +_dl_tlsdesc_dynamic:
> +       _CET_ENDBR
> +       /* Preserve call-clobbered registers that we modify.
> +          We need two scratch regs anyway.  */
> +       movq    %rsi, -16(%rsp)
> +       mov     %fs:DTV_OFFSET, %RSI_LP
> +       movq    %rdi, -8(%rsp)
> +       movq    TLSDESC_ARG(%rax), %rdi
> +       movq    (%rsi), %rax
> +       cmpq    %rax, TLSDESC_GEN_COUNT(%rdi)
> +       ja      2f
> +       movq    TLSDESC_MODID(%rdi), %rax
> +       salq    $4, %rax
> +       movq    (%rax,%rsi), %rax
> +       cmpq    $-1, %rax
> +       je      2f
> +       addq    TLSDESC_MODOFF(%rdi), %rax
> +1:
> +       movq    -16(%rsp), %rsi
> +       sub     %fs:0, %RAX_LP
> +       movq    -8(%rsp), %rdi
> +       ret
> +2:
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       movq    %rbx, -24(%rsp)
> +       mov     %RSP_LP, %RBX_LP
> +       cfi_def_cfa_register(%rbx)
> +       and     $-STATE_SAVE_ALIGNMENT, %RSP_LP
> +#endif
> +#ifdef REGISTER_SAVE_AREA
> +# if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       /* STATE_SAVE_OFFSET has space for 8 integer registers.  But we
> +          need space for RCX, RDX, RSI, RDI, R8, R9, R10 and R11, plus
> +          RBX above.  */
> +       sub     $(REGISTER_SAVE_AREA + STATE_SAVE_ALIGNMENT), %RSP_LP
> +# else
> +       sub     $REGISTER_SAVE_AREA, %RSP_LP
> +       cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
> +# endif
> +#else
> +       /* Allocate stack space of the required size to save the state.  */
> +       sub     _rtld_local_ro+RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_SIZE_OFFSET(%rip), %RSP_LP
> +#endif
> +       /* Besides rdi and rsi, saved above, save rcx, rdx, r8, r9,
> +          r10 and r11.  */
> +       movq    %rcx, REGISTER_SAVE_RCX(%rsp)
> +       movq    %rdx, REGISTER_SAVE_RDX(%rsp)
> +       movq    %r8, REGISTER_SAVE_R8(%rsp)
> +       movq    %r9, REGISTER_SAVE_R9(%rsp)
> +       movq    %r10, REGISTER_SAVE_R10(%rsp)
> +       movq    %r11, REGISTER_SAVE_R11(%rsp)
> +#ifdef USE_FXSAVE
> +       fxsave  STATE_SAVE_OFFSET(%rsp)
> +#else
> +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> +       xorl    %edx, %edx
> +       /* Clear the XSAVE Header.  */
> +# ifdef USE_XSAVE
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8)(%rsp)
> +# endif
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 2)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 3)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 4)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 5)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 6)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 7)(%rsp)
> +# ifdef USE_XSAVE
> +       xsave   STATE_SAVE_OFFSET(%rsp)
> +# else
> +       xsavec  STATE_SAVE_OFFSET(%rsp)
> +# endif
> +#endif
> +       /* %rdi already points to the tlsinfo data structure.  */
> +       call    HIDDEN_JUMPTARGET (__tls_get_addr)
> +       # Get register content back.
> +#ifdef USE_FXSAVE
> +       fxrstor STATE_SAVE_OFFSET(%rsp)
> +#else
> +       /* Save and retore __tls_get_addr return value stored in RAX.  */
> +       mov     %RAX_LP, %RCX_LP
> +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> +       xorl    %edx, %edx
> +       xrstor  STATE_SAVE_OFFSET(%rsp)
> +       mov     %RCX_LP, %RAX_LP
> +#endif
> +       movq    REGISTER_SAVE_R11(%rsp), %r11
> +       movq    REGISTER_SAVE_R10(%rsp), %r10
> +       movq    REGISTER_SAVE_R9(%rsp), %r9
> +       movq    REGISTER_SAVE_R8(%rsp), %r8
> +       movq    REGISTER_SAVE_RDX(%rsp), %rdx
> +       movq    REGISTER_SAVE_RCX(%rsp), %rcx
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       mov     %RBX_LP, %RSP_LP
> +       cfi_def_cfa_register(%rsp)
> +       movq    -24(%rsp), %rbx
> +       cfi_restore(%rbx)
> +#else
> +       add     $REGISTER_SAVE_AREA, %RSP_LP
> +       cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
> +#endif
> +       jmp     1b
> +       cfi_endproc
> +       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> +
> +#undef STATE_SAVE_ALIGNMENT
> diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S
> index f748af2ece..ea69f5223a 100644
> --- a/sysdeps/x86_64/dl-tlsdesc.S
> +++ b/sysdeps/x86_64/dl-tlsdesc.S
> @@ -18,7 +18,19 @@
>
>  #include <sysdep.h>
>  #include <tls.h>
> +#include <cpu-features-offsets.h>
> +#include <features-offsets.h>
>  #include "tlsdesc.h"
> +#include "dl-trampoline-save.h"
> +
> +/* Area on stack to save and restore registers used for parameter
> +   passing when calling _dl_tlsdesc_dynamic.  */
> +#define REGISTER_SAVE_RCX      0
> +#define REGISTER_SAVE_RDX      (REGISTER_SAVE_RCX + 8)
> +#define REGISTER_SAVE_R8       (REGISTER_SAVE_RDX + 8)
> +#define REGISTER_SAVE_R9       (REGISTER_SAVE_R8 + 8)
> +#define REGISTER_SAVE_R10      (REGISTER_SAVE_R9 + 8)
> +#define REGISTER_SAVE_R11      (REGISTER_SAVE_R10 + 8)
>
>         .text
>
> @@ -67,80 +79,24 @@ _dl_tlsdesc_undefweak:
>         .size   _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
>
>  #ifdef SHARED
> -       .hidden _dl_tlsdesc_dynamic
> -       .global _dl_tlsdesc_dynamic
> -       .type   _dl_tlsdesc_dynamic,@function
> -
> -     /* %rax points to the TLS descriptor, such that 0(%rax) points to
> -       _dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct
> -       tlsdesc_dynamic_arg object.  It must return in %rax the offset
> -       between the thread pointer and the object denoted by the
> -       argument, without clobbering any registers.
> -
> -       The assembly code that follows is a rendition of the following
> -       C code, hand-optimized a little bit.
> -
> -ptrdiff_t
> -_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax"))
> -{
> -  struct tlsdesc_dynamic_arg *td = tdp->arg;
> -  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> -  if (__builtin_expect (td->gen_count <= dtv[0].counter
> -                       && (dtv[td->tlsinfo.ti_module].pointer.val
> -                           != TLS_DTV_UNALLOCATED),
> -                       1))
> -    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> -      - __thread_pointer;
> -
> -  return __tls_get_addr_internal (&td->tlsinfo) - __thread_pointer;
> -}
> -*/
> -       cfi_startproc
> -       .align 16
> -_dl_tlsdesc_dynamic:
> -       _CET_ENDBR
> -       /* Preserve call-clobbered registers that we modify.
> -          We need two scratch regs anyway.  */
> -       movq    %rsi, -16(%rsp)
> -       mov     %fs:DTV_OFFSET, %RSI_LP
> -       movq    %rdi, -8(%rsp)
> -       movq    TLSDESC_ARG(%rax), %rdi
> -       movq    (%rsi), %rax
> -       cmpq    %rax, TLSDESC_GEN_COUNT(%rdi)
> -       ja      .Lslow
> -       movq    TLSDESC_MODID(%rdi), %rax
> -       salq    $4, %rax
> -       movq    (%rax,%rsi), %rax
> -       cmpq    $-1, %rax
> -       je      .Lslow
> -       addq    TLSDESC_MODOFF(%rdi), %rax
> -.Lret:
> -       movq    -16(%rsp), %rsi
> -       sub     %fs:0, %RAX_LP
> -       movq    -8(%rsp), %rdi
> -       ret
> -.Lslow:
> -       /* Besides rdi and rsi, saved above, save rdx, rcx, r8, r9,
> -          r10 and r11.  Also, align the stack, that's off by 8 bytes.  */
> -       subq    $72, %rsp
> -       cfi_adjust_cfa_offset (72)
> -       movq    %rdx, 8(%rsp)
> -       movq    %rcx, 16(%rsp)
> -       movq    %r8, 24(%rsp)
> -       movq    %r9, 32(%rsp)
> -       movq    %r10, 40(%rsp)
> -       movq    %r11, 48(%rsp)
> -       /* %rdi already points to the tlsinfo data structure.  */
> -       call    HIDDEN_JUMPTARGET (__tls_get_addr)
> -       movq    8(%rsp), %rdx
> -       movq    16(%rsp), %rcx
> -       movq    24(%rsp), %r8
> -       movq    32(%rsp), %r9
> -       movq    40(%rsp), %r10
> -       movq    48(%rsp), %r11
> -       addq    $72, %rsp
> -       cfi_adjust_cfa_offset (-72)
> -       jmp     .Lret
> -       cfi_endproc
> -       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> +# define USE_FXSAVE
> +# define STATE_SAVE_ALIGNMENT  16
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_fxsave
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_FXSAVE
> +
> +# define USE_XSAVE
> +# define STATE_SAVE_ALIGNMENT  64
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsave
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_XSAVE
> +
> +# define USE_XSAVEC
> +# define STATE_SAVE_ALIGNMENT  64
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsavec
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_XSAVEC
>  #endif /* SHARED */
> diff --git a/sysdeps/x86_64/dl-trampoline-save.h b/sysdeps/x86_64/dl-trampoline-save.h
> new file mode 100644
> index 0000000000..84eac4a8ac
> --- /dev/null
> +++ b/sysdeps/x86_64/dl-trampoline-save.h
> @@ -0,0 +1,34 @@
> +/* x86-64 PLT trampoline register save macros.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef DL_STACK_ALIGNMENT
> +/* Due to GCC bug:
> +
> +   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> +
> +   __tls_get_addr may be called with 8-byte stack alignment.  Although
> +   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
> +   that stack will be always aligned at 16 bytes.  */
> +# define DL_STACK_ALIGNMENT 8
> +#endif
> +
> +/* True if _dl_runtime_resolve should align stack for STATE_SAVE or align
> +   stack to 16 bytes before calling _dl_fixup.  */
> +#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> +  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> +   || 16 > DL_STACK_ALIGNMENT)
> diff --git a/sysdeps/x86_64/dl-trampoline-state.h b/sysdeps/x86_64/dl-trampoline-state.h
> new file mode 100644
> index 0000000000..575f120797
> --- /dev/null
> +++ b/sysdeps/x86_64/dl-trampoline-state.h
> @@ -0,0 +1,51 @@
> +/* x86-64 PLT dl-trampoline state macros.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#if (STATE_SAVE_ALIGNMENT % 16) != 0
> +# error STATE_SAVE_ALIGNMENT must be multiple of 16
> +#endif
> +
> +#if (STATE_SAVE_OFFSET % STATE_SAVE_ALIGNMENT) != 0
> +# error STATE_SAVE_OFFSET must be multiple of STATE_SAVE_ALIGNMENT
> +#endif
> +
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +/* Local stack area before jumping to function address: RBX.  */
> +# define LOCAL_STORAGE_AREA    8
> +# define BASE                  rbx
> +# ifdef USE_FXSAVE
> +/* Use fxsave to save XMM registers.  */
> +#  define REGISTER_SAVE_AREA   (512 + STATE_SAVE_OFFSET)
> +#  if (REGISTER_SAVE_AREA % 16) != 0
> +#   error REGISTER_SAVE_AREA must be multiple of 16
> +#  endif
> +# endif
> +#else
> +# ifndef USE_FXSAVE
> +#  error USE_FXSAVE must be defined
> +# endif
> +/* Use fxsave to save XMM registers.  */
> +# define REGISTER_SAVE_AREA    (512 + STATE_SAVE_OFFSET + 8)
> +/* Local stack area before jumping to function address:  All saved
> +   registers.  */
> +# define LOCAL_STORAGE_AREA    REGISTER_SAVE_AREA
> +# define BASE                  rsp
> +# if (REGISTER_SAVE_AREA % 16) != 8
> +#  error REGISTER_SAVE_AREA must be odd multiple of 8
> +# endif
> +#endif
> diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S
> index b2e7e0f69b..87c5137837 100644
> --- a/sysdeps/x86_64/dl-trampoline.S
> +++ b/sysdeps/x86_64/dl-trampoline.S
> @@ -22,25 +22,7 @@
>  #include <features-offsets.h>
>  #include <link-defines.h>
>  #include <isa-level.h>
> -
> -#ifndef DL_STACK_ALIGNMENT
> -/* Due to GCC bug:
> -
> -   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> -
> -   __tls_get_addr may be called with 8-byte stack alignment.  Although
> -   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
> -   that stack will be always aligned at 16 bytes.  We use unaligned
> -   16-byte move to load and store SSE registers, which has no penalty
> -   on modern processors if stack is 16-byte aligned.  */
> -# define DL_STACK_ALIGNMENT 8
> -#endif
> -
> -/* True if _dl_runtime_resolve should align stack for STATE_SAVE or align
> -   stack to 16 bytes before calling _dl_fixup.  */
> -#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> -  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> -   || 16 > DL_STACK_ALIGNMENT)
> +#include "dl-trampoline-save.h"
>
>  /* Area on stack to save and restore registers used for parameter
>     passing when calling _dl_fixup.  */
> diff --git a/sysdeps/x86_64/dl-trampoline.h b/sysdeps/x86_64/dl-trampoline.h
> index f55c6ea040..d9ccfb40d4 100644
> --- a/sysdeps/x86_64/dl-trampoline.h
> +++ b/sysdeps/x86_64/dl-trampoline.h
> @@ -27,39 +27,7 @@
>  # undef LOCAL_STORAGE_AREA
>  # undef BASE
>
> -# if (STATE_SAVE_ALIGNMENT % 16) != 0
> -#  error STATE_SAVE_ALIGNMENT must be multiple of 16
> -# endif
> -
> -# if (STATE_SAVE_OFFSET % STATE_SAVE_ALIGNMENT) != 0
> -#  error STATE_SAVE_OFFSET must be multiple of STATE_SAVE_ALIGNMENT
> -# endif
> -
> -# if DL_RUNTIME_RESOLVE_REALIGN_STACK
> -/* Local stack area before jumping to function address: RBX.  */
> -#  define LOCAL_STORAGE_AREA   8
> -#  define BASE                 rbx
> -#  ifdef USE_FXSAVE
> -/* Use fxsave to save XMM registers.  */
> -#   define REGISTER_SAVE_AREA  (512 + STATE_SAVE_OFFSET)
> -#   if (REGISTER_SAVE_AREA % 16) != 0
> -#    error REGISTER_SAVE_AREA must be multiple of 16
> -#   endif
> -#  endif
> -# else
> -#  ifndef USE_FXSAVE
> -#   error USE_FXSAVE must be defined
> -#  endif
> -/* Use fxsave to save XMM registers.  */
> -#  define REGISTER_SAVE_AREA   (512 + STATE_SAVE_OFFSET + 8)
> -/* Local stack area before jumping to function address:  All saved
> -   registers.  */
> -#  define LOCAL_STORAGE_AREA   REGISTER_SAVE_AREA
> -#  define BASE                 rsp
> -#  if (REGISTER_SAVE_AREA % 16) != 8
> -#   error REGISTER_SAVE_AREA must be odd multiple of 8
> -#  endif
> -# endif
> +# include "dl-trampoline-state.h"
>
>         .globl _dl_runtime_resolve
>         .hidden _dl_runtime_resolve
> --
> 2.43.0
>
H.J. Lu Feb. 24, 2024, 5:30 p.m. UTC | #2
On Sat, Feb 24, 2024 at 9:09 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Fri, Feb 16, 2024 at 9:17 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > Compiler generates the following instruction sequence for GNU2 dynamic
> > TLS access:
> >
> >         leaq    tls_var@TLSDESC(%rip), %rax
> >         call    *tls_var@TLSCALL(%rax)
> >
> > or
> >
> >         leal    tls_var@TLSDESC(%ebx), %eax
> >         call    *tls_var@TLSCALL(%eax)
> >
> > CALL instruction is transparent to compiler which assumes all registers,
> > except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
> > _dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
> > path.  __tls_get_addr is a normal function which doesn't preserve any
> > caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
> > caller-saved registers, but didn't preserve any other caller-saved
> > registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
> > XSAVE and XSAVEC to save and restore all caller-saved registers.  This
> > fixes BZ #31372.
> >
> > Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
> > to optimize elf_machine_runtime_setup.
> > ---
> >  elf/Makefile                                 |  14 ++
> >  elf/tst-gnu2-tls2.c                          | 120 ++++++++++++
> >  elf/tst-gnu2-tls2.h                          |  36 ++++
> >  elf/tst-gnu2-tls2mod0.c                      |  31 +++
> >  elf/tst-gnu2-tls2mod1.c                      |  31 +++
> >  elf/tst-gnu2-tls2mod2.c                      |  31 +++
> >  sysdeps/i386/dl-machine.h                    |   2 +-
> >  sysdeps/i386/dl-tlsdesc-dynamic.h            | 190 +++++++++++++++++++
> >  sysdeps/i386/dl-tlsdesc.S                    | 115 +++++------
> >  sysdeps/x86/Makefile                         |   7 +-
> >  sysdeps/x86/cpu-features.c                   |  56 +++++-
> >  sysdeps/x86/dl-procinfo.c                    |  16 ++
> >  sysdeps/{x86_64 => x86}/features-offsets.sym |   2 +
> >  sysdeps/x86/sysdep.h                         |   6 +
> >  sysdeps/x86/tst-gnu2-tls2.c                  |  20 ++
> >  sysdeps/x86_64/Makefile                      |   2 +-
> >  sysdeps/x86_64/dl-machine.h                  |  19 +-
> >  sysdeps/x86_64/dl-procinfo.c                 |  16 ++
> >  sysdeps/x86_64/dl-tlsdesc-dynamic.h          | 166 ++++++++++++++++
> >  sysdeps/x86_64/dl-tlsdesc.S                  | 108 ++++-------
> >  sysdeps/x86_64/dl-trampoline-save.h          |  34 ++++
> >  sysdeps/x86_64/dl-trampoline-state.h         |  51 +++++
> >  sysdeps/x86_64/dl-trampoline.S               |  20 +-
> >  sysdeps/x86_64/dl-trampoline.h               |  34 +---
> >  24 files changed, 914 insertions(+), 213 deletions(-)
> >  create mode 100644 elf/tst-gnu2-tls2.c
> >  create mode 100644 elf/tst-gnu2-tls2.h
> >  create mode 100644 elf/tst-gnu2-tls2mod0.c
> >  create mode 100644 elf/tst-gnu2-tls2mod1.c
> >  create mode 100644 elf/tst-gnu2-tls2mod2.c
> >  create mode 100644 sysdeps/i386/dl-tlsdesc-dynamic.h
> >  rename sysdeps/{x86_64 => x86}/features-offsets.sym (89%)
> >  create mode 100644 sysdeps/x86/tst-gnu2-tls2.c
> >  create mode 100644 sysdeps/x86_64/dl-tlsdesc-dynamic.h
> >  create mode 100644 sysdeps/x86_64/dl-trampoline-save.h
> >  create mode 100644 sysdeps/x86_64/dl-trampoline-state.h
> >
> > diff --git a/elf/Makefile b/elf/Makefile
> > index 5d78b659ce..030db4d207 100644
> > --- a/elf/Makefile
> > +++ b/elf/Makefile
> > @@ -424,6 +424,7 @@ tests += \
> >    tst-glibc-hwcaps-prepend \
> >    tst-global1 \
> >    tst-global2 \
> > +  tst-gnu2-tls2 \
> >    tst-initfinilazyfail \
> >    tst-initorder \
> >    tst-initorder2 \
> > @@ -846,6 +847,9 @@ modules-names += \
> >    tst-filterobj-flt \
> >    tst-finilazyfailmod \
> >    tst-globalmod2 \
> > +  tst-gnu2-tls2mod0 \
> > +  tst-gnu2-tls2mod1 \
> > +  tst-gnu2-tls2mod2 \
> >    tst-initlazyfailmod \
> >    tst-initorder2a \
> >    tst-initorder2b \
> > @@ -3044,8 +3048,18 @@ $(objpfx)tst-tlsgap.out: \
> >    $(objpfx)tst-tlsgap-mod0.so \
> >    $(objpfx)tst-tlsgap-mod1.so \
> >    $(objpfx)tst-tlsgap-mod2.so
> > +
> > +$(objpfx)tst-gnu2-tls2: $(shared-thread-library)
> > +$(objpfx)tst-gnu2-tls2.out: \
> > +  $(objpfx)tst-gnu2-tls2mod0.so \
> > +  $(objpfx)tst-gnu2-tls2mod1.so \
> > +  $(objpfx)tst-gnu2-tls2mod2.so
> > +
> >  ifeq (yes,$(have-mtls-dialect-gnu2))
> >  CFLAGS-tst-tlsgap-mod0.c += -mtls-dialect=gnu2
> >  CFLAGS-tst-tlsgap-mod1.c += -mtls-dialect=gnu2
> >  CFLAGS-tst-tlsgap-mod2.c += -mtls-dialect=gnu2
> > +CFLAGS-tst-gnu2-tls2mod0.c += -mtls-dialect=gnu2
> > +CFLAGS-tst-gnu2-tls2mod1.c += -mtls-dialect=gnu2
> > +CFLAGS-tst-gnu2-tls2mod2.c += -mtls-dialect=gnu2
> >  endif
> > diff --git a/elf/tst-gnu2-tls2.c b/elf/tst-gnu2-tls2.c
> > new file mode 100644
> > index 0000000000..8039ba614d
> > --- /dev/null
> > +++ b/elf/tst-gnu2-tls2.c
> > @@ -0,0 +1,120 @@
> > +/* Test TLSDESC relocation.
> > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <http://www.gnu.org/licenses/>.  */
> > +
> > +#include <stdio.h>
> > +#include <stdlib.h>
> > +#include <string.h>
> > +#include <dlfcn.h>
> > +#include <pthread.h>
> > +#include <support/xdlfcn.h>
> > +#include <support/xthread.h>
> > +#include <support/check.h>
> > +#include <support/test-driver.h>
> > +#include "tst-gnu2-tls2.h"
> > +
> > +#ifndef IS_SUPPORTED
> > +# define IS_SUPPORTED() true
> > +#endif
> > +
> > +/* An architecture can define it to clobber caller-saved registers in
> > +   malloc below to verify that the implicit TLSDESC call won't change
> > +   caller-saved registers.  */
> > +#ifndef PREPARE_MALLOC
> > +# define PREPARE_MALLOC()
> > +#endif
> > +
> > +extern void * __libc_malloc (size_t);
> > +
> > +size_t malloc_counter = 0;
> > +
> > +void *
> > +malloc (size_t n)
> > +{
> > +  PREPARE_MALLOC ();
> > +  malloc_counter++;
> > +  return __libc_malloc (n);
> > +}
> > +
> > +static void *mod[3];
> > +#define MOD(i) "tst-gnu2-tls2mod" #i ".so"
> > +static const char *modname[3] = { MOD(0), MOD(1), MOD(2) };
> > +#undef MOD
> > +
> > +static void
> > +open_mod (int i)
> > +{
> > +  mod[i] = xdlopen (modname[i], RTLD_LAZY);
> > +  printf ("open %s\n", modname[i]);
> > +}
> > +
> > +static void
> > +close_mod (int i)
> > +{
> > +  xdlclose (mod[i]);
> > +  mod[i] = NULL;
> > +  printf ("close %s\n", modname[i]);
> > +}
> > +
> > +static void
> > +access_mod (int i, const char *sym)
> > +{
> > +  struct tls var = { -1, -1, -1, -1 };
> > +  struct tls *(*f) (struct tls *) = xdlsym (mod[i], sym);
> > +  /* Check that our malloc is called.  */
> > +  malloc_counter = 0;
> > +  struct tls *p = f (&var);
> > +  TEST_VERIFY (malloc_counter != 0);
> > +  printf ("access %s: %s() = %p\n", modname[i], sym, p);
> > +  TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
> > +  ++(p->a);
> > +}
> > +
> > +static void *
> > +start (void *arg)
> > +{
> > +  /* The DTV generation is at the last dlopen of mod0 and the
> > +     entry for mod1 is NULL.  */
> > +
> > +  open_mod (1); /* Reuse modid of mod1. Uses dynamic TLS.  */
> > +
> > +  /* Force the slow path in GNU2 TLS descriptor call.  */
> > +  access_mod (1, "apply_tls");
> > +
> > +  return arg;
> > +}
> > +
> > +static int
> > +do_test (void)
> > +{
> > +  if (!IS_SUPPORTED ())
> > +    return EXIT_UNSUPPORTED;
> > +
> > +  open_mod (0);
> > +  open_mod (1);
> > +  open_mod (2);
> > +  close_mod (0);
> > +  close_mod (1); /* Create modid gap at mod1.  */
> > +  open_mod (0); /* Reuse modid of mod0, bump generation count.  */
> > +
> > +  /* Create a thread where DTV of mod1 is NULL.  */
> > +  pthread_t t = xpthread_create (NULL, start, NULL);
> > +  xpthread_join (t);
> > +  return 0;
> > +}
> > +
> > +#include <support/test-driver.c>
>
> The change looks good but this is still failing on arm.
>
> ```
> FAIL: elf/tst-gnu2-tls2
> original exit status 1
> open tst-gnu2-tls2mod0.so
> open tst-gnu2-tls2mod1.so
> open tst-gnu2-tls2mod2.so
> close tst-gnu2-tls2mod0.so
> close tst-gnu2-tls2mod1.so
> open tst-gnu2-tls2mod0.so
> open tst-gnu2-tls2mod1.so
> Didn't expect signal from child: got `Segmentation fault'
> ```
>
> HJ can you add some more logging to its clear exactly where
> the fault is? (looks to be malloc or xdlsym).

The new test may fail on targets which don't preserve all
caller-saved registers in _dl_tlsdesc_dynamic.

> Are there any other arch this is failing on? I.e is this an arm
> bug or buggy test?
>

It is a bug on arm:

https://github.com/zatrazz/glibc/commits/azanella/tls-descriptor-fixes-arm/

...
Noah Goldstein Feb. 24, 2024, 5:39 p.m. UTC | #3
On Sat, Feb 24, 2024 at 11:31 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Sat, Feb 24, 2024 at 9:09 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >
> > On Fri, Feb 16, 2024 at 9:17 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >
> > > Compiler generates the following instruction sequence for GNU2 dynamic
> > > TLS access:
> > >
> > >         leaq    tls_var@TLSDESC(%rip), %rax
> > >         call    *tls_var@TLSCALL(%rax)
> > >
> > > or
> > >
> > >         leal    tls_var@TLSDESC(%ebx), %eax
> > >         call    *tls_var@TLSCALL(%eax)
> > >
> > > CALL instruction is transparent to compiler which assumes all registers,
> > > except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
> > > _dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
> > > path.  __tls_get_addr is a normal function which doesn't preserve any
> > > caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
> > > caller-saved registers, but didn't preserve any other caller-saved
> > > registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
> > > XSAVE and XSAVEC to save and restore all caller-saved registers.  This
> > > fixes BZ #31372.
> > >
> > > Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
> > > to optimize elf_machine_runtime_setup.
> > > ---
> > >  elf/Makefile                                 |  14 ++
> > >  elf/tst-gnu2-tls2.c                          | 120 ++++++++++++
> > >  elf/tst-gnu2-tls2.h                          |  36 ++++
> > >  elf/tst-gnu2-tls2mod0.c                      |  31 +++
> > >  elf/tst-gnu2-tls2mod1.c                      |  31 +++
> > >  elf/tst-gnu2-tls2mod2.c                      |  31 +++
> > >  sysdeps/i386/dl-machine.h                    |   2 +-
> > >  sysdeps/i386/dl-tlsdesc-dynamic.h            | 190 +++++++++++++++++++
> > >  sysdeps/i386/dl-tlsdesc.S                    | 115 +++++------
> > >  sysdeps/x86/Makefile                         |   7 +-
> > >  sysdeps/x86/cpu-features.c                   |  56 +++++-
> > >  sysdeps/x86/dl-procinfo.c                    |  16 ++
> > >  sysdeps/{x86_64 => x86}/features-offsets.sym |   2 +
> > >  sysdeps/x86/sysdep.h                         |   6 +
> > >  sysdeps/x86/tst-gnu2-tls2.c                  |  20 ++
> > >  sysdeps/x86_64/Makefile                      |   2 +-
> > >  sysdeps/x86_64/dl-machine.h                  |  19 +-
> > >  sysdeps/x86_64/dl-procinfo.c                 |  16 ++
> > >  sysdeps/x86_64/dl-tlsdesc-dynamic.h          | 166 ++++++++++++++++
> > >  sysdeps/x86_64/dl-tlsdesc.S                  | 108 ++++-------
> > >  sysdeps/x86_64/dl-trampoline-save.h          |  34 ++++
> > >  sysdeps/x86_64/dl-trampoline-state.h         |  51 +++++
> > >  sysdeps/x86_64/dl-trampoline.S               |  20 +-
> > >  sysdeps/x86_64/dl-trampoline.h               |  34 +---
> > >  24 files changed, 914 insertions(+), 213 deletions(-)
> > >  create mode 100644 elf/tst-gnu2-tls2.c
> > >  create mode 100644 elf/tst-gnu2-tls2.h
> > >  create mode 100644 elf/tst-gnu2-tls2mod0.c
> > >  create mode 100644 elf/tst-gnu2-tls2mod1.c
> > >  create mode 100644 elf/tst-gnu2-tls2mod2.c
> > >  create mode 100644 sysdeps/i386/dl-tlsdesc-dynamic.h
> > >  rename sysdeps/{x86_64 => x86}/features-offsets.sym (89%)
> > >  create mode 100644 sysdeps/x86/tst-gnu2-tls2.c
> > >  create mode 100644 sysdeps/x86_64/dl-tlsdesc-dynamic.h
> > >  create mode 100644 sysdeps/x86_64/dl-trampoline-save.h
> > >  create mode 100644 sysdeps/x86_64/dl-trampoline-state.h
> > >
> > > diff --git a/elf/Makefile b/elf/Makefile
> > > index 5d78b659ce..030db4d207 100644
> > > --- a/elf/Makefile
> > > +++ b/elf/Makefile
> > > @@ -424,6 +424,7 @@ tests += \
> > >    tst-glibc-hwcaps-prepend \
> > >    tst-global1 \
> > >    tst-global2 \
> > > +  tst-gnu2-tls2 \
> > >    tst-initfinilazyfail \
> > >    tst-initorder \
> > >    tst-initorder2 \
> > > @@ -846,6 +847,9 @@ modules-names += \
> > >    tst-filterobj-flt \
> > >    tst-finilazyfailmod \
> > >    tst-globalmod2 \
> > > +  tst-gnu2-tls2mod0 \
> > > +  tst-gnu2-tls2mod1 \
> > > +  tst-gnu2-tls2mod2 \
> > >    tst-initlazyfailmod \
> > >    tst-initorder2a \
> > >    tst-initorder2b \
> > > @@ -3044,8 +3048,18 @@ $(objpfx)tst-tlsgap.out: \
> > >    $(objpfx)tst-tlsgap-mod0.so \
> > >    $(objpfx)tst-tlsgap-mod1.so \
> > >    $(objpfx)tst-tlsgap-mod2.so
> > > +
> > > +$(objpfx)tst-gnu2-tls2: $(shared-thread-library)
> > > +$(objpfx)tst-gnu2-tls2.out: \
> > > +  $(objpfx)tst-gnu2-tls2mod0.so \
> > > +  $(objpfx)tst-gnu2-tls2mod1.so \
> > > +  $(objpfx)tst-gnu2-tls2mod2.so
> > > +
> > >  ifeq (yes,$(have-mtls-dialect-gnu2))
> > >  CFLAGS-tst-tlsgap-mod0.c += -mtls-dialect=gnu2
> > >  CFLAGS-tst-tlsgap-mod1.c += -mtls-dialect=gnu2
> > >  CFLAGS-tst-tlsgap-mod2.c += -mtls-dialect=gnu2
> > > +CFLAGS-tst-gnu2-tls2mod0.c += -mtls-dialect=gnu2
> > > +CFLAGS-tst-gnu2-tls2mod1.c += -mtls-dialect=gnu2
> > > +CFLAGS-tst-gnu2-tls2mod2.c += -mtls-dialect=gnu2
> > >  endif
> > > diff --git a/elf/tst-gnu2-tls2.c b/elf/tst-gnu2-tls2.c
> > > new file mode 100644
> > > index 0000000000..8039ba614d
> > > --- /dev/null
> > > +++ b/elf/tst-gnu2-tls2.c
> > > @@ -0,0 +1,120 @@
> > > +/* Test TLSDESC relocation.
> > > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > > +   This file is part of the GNU C Library.
> > > +
> > > +   The GNU C Library is free software; you can redistribute it and/or
> > > +   modify it under the terms of the GNU Lesser General Public
> > > +   License as published by the Free Software Foundation; either
> > > +   version 2.1 of the License, or (at your option) any later version.
> > > +
> > > +   The GNU C Library is distributed in the hope that it will be useful,
> > > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > > +   Lesser General Public License for more details.
> > > +
> > > +   You should have received a copy of the GNU Lesser General Public
> > > +   License along with the GNU C Library; if not, see
> > > +   <http://www.gnu.org/licenses/>.  */
> > > +
> > > +#include <stdio.h>
> > > +#include <stdlib.h>
> > > +#include <string.h>
> > > +#include <dlfcn.h>
> > > +#include <pthread.h>
> > > +#include <support/xdlfcn.h>
> > > +#include <support/xthread.h>
> > > +#include <support/check.h>
> > > +#include <support/test-driver.h>
> > > +#include "tst-gnu2-tls2.h"
> > > +
> > > +#ifndef IS_SUPPORTED
> > > +# define IS_SUPPORTED() true
> > > +#endif
> > > +
> > > +/* An architecture can define it to clobber caller-saved registers in
> > > +   malloc below to verify that the implicit TLSDESC call won't change
> > > +   caller-saved registers.  */
> > > +#ifndef PREPARE_MALLOC
> > > +# define PREPARE_MALLOC()
> > > +#endif
> > > +
> > > +extern void * __libc_malloc (size_t);
> > > +
> > > +size_t malloc_counter = 0;
> > > +
> > > +void *
> > > +malloc (size_t n)
> > > +{
> > > +  PREPARE_MALLOC ();
> > > +  malloc_counter++;
> > > +  return __libc_malloc (n);
> > > +}
> > > +
> > > +static void *mod[3];
> > > +#define MOD(i) "tst-gnu2-tls2mod" #i ".so"
> > > +static const char *modname[3] = { MOD(0), MOD(1), MOD(2) };
> > > +#undef MOD
> > > +
> > > +static void
> > > +open_mod (int i)
> > > +{
> > > +  mod[i] = xdlopen (modname[i], RTLD_LAZY);
> > > +  printf ("open %s\n", modname[i]);
> > > +}
> > > +
> > > +static void
> > > +close_mod (int i)
> > > +{
> > > +  xdlclose (mod[i]);
> > > +  mod[i] = NULL;
> > > +  printf ("close %s\n", modname[i]);
> > > +}
> > > +
> > > +static void
> > > +access_mod (int i, const char *sym)
> > > +{
> > > +  struct tls var = { -1, -1, -1, -1 };
> > > +  struct tls *(*f) (struct tls *) = xdlsym (mod[i], sym);
> > > +  /* Check that our malloc is called.  */
> > > +  malloc_counter = 0;
> > > +  struct tls *p = f (&var);
> > > +  TEST_VERIFY (malloc_counter != 0);
> > > +  printf ("access %s: %s() = %p\n", modname[i], sym, p);
> > > +  TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
> > > +  ++(p->a);
> > > +}
> > > +
> > > +static void *
> > > +start (void *arg)
> > > +{
> > > +  /* The DTV generation is at the last dlopen of mod0 and the
> > > +     entry for mod1 is NULL.  */
> > > +
> > > +  open_mod (1); /* Reuse modid of mod1. Uses dynamic TLS.  */
> > > +
> > > +  /* Force the slow path in GNU2 TLS descriptor call.  */
> > > +  access_mod (1, "apply_tls");
> > > +
> > > +  return arg;
> > > +}
> > > +
> > > +static int
> > > +do_test (void)
> > > +{
> > > +  if (!IS_SUPPORTED ())
> > > +    return EXIT_UNSUPPORTED;
> > > +
> > > +  open_mod (0);
> > > +  open_mod (1);
> > > +  open_mod (2);
> > > +  close_mod (0);
> > > +  close_mod (1); /* Create modid gap at mod1.  */
> > > +  open_mod (0); /* Reuse modid of mod0, bump generation count.  */
> > > +
> > > +  /* Create a thread where DTV of mod1 is NULL.  */
> > > +  pthread_t t = xpthread_create (NULL, start, NULL);
> > > +  xpthread_join (t);
> > > +  return 0;
> > > +}
> > > +
> > > +#include <support/test-driver.c>
> >
> > The change looks good but this is still failing on arm.
> >
> > ```
> > FAIL: elf/tst-gnu2-tls2
> > original exit status 1
> > open tst-gnu2-tls2mod0.so
> > open tst-gnu2-tls2mod1.so
> > open tst-gnu2-tls2mod2.so
> > close tst-gnu2-tls2mod0.so
> > close tst-gnu2-tls2mod1.so
> > open tst-gnu2-tls2mod0.so
> > open tst-gnu2-tls2mod1.so
> > Didn't expect signal from child: got `Segmentation fault'
> > ```
> >
> > HJ can you add some more logging to its clear exactly where
> > the fault is? (looks to be malloc or xdlsym).
>
> The new test may fail on targets which don't preserve all
> caller-saved registers in _dl_tlsdesc_dynamic.
>
> > Are there any other arch this is failing on? I.e is this an arm
> > bug or buggy test?
> >
>
> It is a bug on arm:
>
> https://github.com/zatrazz/glibc/commits/azanella/tls-descriptor-fixes-arm/

Is anyone working on a fix for arm?
>
> ...
>
> --
> H.J.
H.J. Lu Feb. 24, 2024, 6 p.m. UTC | #4
On Sat, Feb 24, 2024 at 9:39 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Sat, Feb 24, 2024 at 11:31 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Sat, Feb 24, 2024 at 9:09 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > >
> > > On Fri, Feb 16, 2024 at 9:17 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> > > >
> > > > Compiler generates the following instruction sequence for GNU2 dynamic
> > > > TLS access:
> > > >
> > > >         leaq    tls_var@TLSDESC(%rip), %rax
> > > >         call    *tls_var@TLSCALL(%rax)
> > > >
> > > > or
> > > >
> > > >         leal    tls_var@TLSDESC(%ebx), %eax
> > > >         call    *tls_var@TLSCALL(%eax)
> > > >
> > > > CALL instruction is transparent to compiler which assumes all registers,
> > > > except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
> > > > _dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
> > > > path.  __tls_get_addr is a normal function which doesn't preserve any
> > > > caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
> > > > caller-saved registers, but didn't preserve any other caller-saved
> > > > registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
> > > > XSAVE and XSAVEC to save and restore all caller-saved registers.  This
> > > > fixes BZ #31372.
> > > >
> > > > Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
> > > > to optimize elf_machine_runtime_setup.
> > > > ---
> > > >  elf/Makefile                                 |  14 ++
> > > >  elf/tst-gnu2-tls2.c                          | 120 ++++++++++++
> > > >  elf/tst-gnu2-tls2.h                          |  36 ++++
> > > >  elf/tst-gnu2-tls2mod0.c                      |  31 +++
> > > >  elf/tst-gnu2-tls2mod1.c                      |  31 +++
> > > >  elf/tst-gnu2-tls2mod2.c                      |  31 +++
> > > >  sysdeps/i386/dl-machine.h                    |   2 +-
> > > >  sysdeps/i386/dl-tlsdesc-dynamic.h            | 190 +++++++++++++++++++
> > > >  sysdeps/i386/dl-tlsdesc.S                    | 115 +++++------
> > > >  sysdeps/x86/Makefile                         |   7 +-
> > > >  sysdeps/x86/cpu-features.c                   |  56 +++++-
> > > >  sysdeps/x86/dl-procinfo.c                    |  16 ++
> > > >  sysdeps/{x86_64 => x86}/features-offsets.sym |   2 +
> > > >  sysdeps/x86/sysdep.h                         |   6 +
> > > >  sysdeps/x86/tst-gnu2-tls2.c                  |  20 ++
> > > >  sysdeps/x86_64/Makefile                      |   2 +-
> > > >  sysdeps/x86_64/dl-machine.h                  |  19 +-
> > > >  sysdeps/x86_64/dl-procinfo.c                 |  16 ++
> > > >  sysdeps/x86_64/dl-tlsdesc-dynamic.h          | 166 ++++++++++++++++
> > > >  sysdeps/x86_64/dl-tlsdesc.S                  | 108 ++++-------
> > > >  sysdeps/x86_64/dl-trampoline-save.h          |  34 ++++
> > > >  sysdeps/x86_64/dl-trampoline-state.h         |  51 +++++
> > > >  sysdeps/x86_64/dl-trampoline.S               |  20 +-
> > > >  sysdeps/x86_64/dl-trampoline.h               |  34 +---
> > > >  24 files changed, 914 insertions(+), 213 deletions(-)
> > > >  create mode 100644 elf/tst-gnu2-tls2.c
> > > >  create mode 100644 elf/tst-gnu2-tls2.h
> > > >  create mode 100644 elf/tst-gnu2-tls2mod0.c
> > > >  create mode 100644 elf/tst-gnu2-tls2mod1.c
> > > >  create mode 100644 elf/tst-gnu2-tls2mod2.c
> > > >  create mode 100644 sysdeps/i386/dl-tlsdesc-dynamic.h
> > > >  rename sysdeps/{x86_64 => x86}/features-offsets.sym (89%)
> > > >  create mode 100644 sysdeps/x86/tst-gnu2-tls2.c
> > > >  create mode 100644 sysdeps/x86_64/dl-tlsdesc-dynamic.h
> > > >  create mode 100644 sysdeps/x86_64/dl-trampoline-save.h
> > > >  create mode 100644 sysdeps/x86_64/dl-trampoline-state.h
> > > >
> > > > diff --git a/elf/Makefile b/elf/Makefile
> > > > index 5d78b659ce..030db4d207 100644
> > > > --- a/elf/Makefile
> > > > +++ b/elf/Makefile
> > > > @@ -424,6 +424,7 @@ tests += \
> > > >    tst-glibc-hwcaps-prepend \
> > > >    tst-global1 \
> > > >    tst-global2 \
> > > > +  tst-gnu2-tls2 \
> > > >    tst-initfinilazyfail \
> > > >    tst-initorder \
> > > >    tst-initorder2 \
> > > > @@ -846,6 +847,9 @@ modules-names += \
> > > >    tst-filterobj-flt \
> > > >    tst-finilazyfailmod \
> > > >    tst-globalmod2 \
> > > > +  tst-gnu2-tls2mod0 \
> > > > +  tst-gnu2-tls2mod1 \
> > > > +  tst-gnu2-tls2mod2 \
> > > >    tst-initlazyfailmod \
> > > >    tst-initorder2a \
> > > >    tst-initorder2b \
> > > > @@ -3044,8 +3048,18 @@ $(objpfx)tst-tlsgap.out: \
> > > >    $(objpfx)tst-tlsgap-mod0.so \
> > > >    $(objpfx)tst-tlsgap-mod1.so \
> > > >    $(objpfx)tst-tlsgap-mod2.so
> > > > +
> > > > +$(objpfx)tst-gnu2-tls2: $(shared-thread-library)
> > > > +$(objpfx)tst-gnu2-tls2.out: \
> > > > +  $(objpfx)tst-gnu2-tls2mod0.so \
> > > > +  $(objpfx)tst-gnu2-tls2mod1.so \
> > > > +  $(objpfx)tst-gnu2-tls2mod2.so
> > > > +
> > > >  ifeq (yes,$(have-mtls-dialect-gnu2))
> > > >  CFLAGS-tst-tlsgap-mod0.c += -mtls-dialect=gnu2
> > > >  CFLAGS-tst-tlsgap-mod1.c += -mtls-dialect=gnu2
> > > >  CFLAGS-tst-tlsgap-mod2.c += -mtls-dialect=gnu2
> > > > +CFLAGS-tst-gnu2-tls2mod0.c += -mtls-dialect=gnu2
> > > > +CFLAGS-tst-gnu2-tls2mod1.c += -mtls-dialect=gnu2
> > > > +CFLAGS-tst-gnu2-tls2mod2.c += -mtls-dialect=gnu2
> > > >  endif
> > > > diff --git a/elf/tst-gnu2-tls2.c b/elf/tst-gnu2-tls2.c
> > > > new file mode 100644
> > > > index 0000000000..8039ba614d
> > > > --- /dev/null
> > > > +++ b/elf/tst-gnu2-tls2.c
> > > > @@ -0,0 +1,120 @@
> > > > +/* Test TLSDESC relocation.
> > > > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > > > +   This file is part of the GNU C Library.
> > > > +
> > > > +   The GNU C Library is free software; you can redistribute it and/or
> > > > +   modify it under the terms of the GNU Lesser General Public
> > > > +   License as published by the Free Software Foundation; either
> > > > +   version 2.1 of the License, or (at your option) any later version.
> > > > +
> > > > +   The GNU C Library is distributed in the hope that it will be useful,
> > > > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > > > +   Lesser General Public License for more details.
> > > > +
> > > > +   You should have received a copy of the GNU Lesser General Public
> > > > +   License along with the GNU C Library; if not, see
> > > > +   <http://www.gnu.org/licenses/>.  */
> > > > +
> > > > +#include <stdio.h>
> > > > +#include <stdlib.h>
> > > > +#include <string.h>
> > > > +#include <dlfcn.h>
> > > > +#include <pthread.h>
> > > > +#include <support/xdlfcn.h>
> > > > +#include <support/xthread.h>
> > > > +#include <support/check.h>
> > > > +#include <support/test-driver.h>
> > > > +#include "tst-gnu2-tls2.h"
> > > > +
> > > > +#ifndef IS_SUPPORTED
> > > > +# define IS_SUPPORTED() true
> > > > +#endif
> > > > +
> > > > +/* An architecture can define it to clobber caller-saved registers in
> > > > +   malloc below to verify that the implicit TLSDESC call won't change
> > > > +   caller-saved registers.  */
> > > > +#ifndef PREPARE_MALLOC
> > > > +# define PREPARE_MALLOC()
> > > > +#endif
> > > > +
> > > > +extern void * __libc_malloc (size_t);
> > > > +
> > > > +size_t malloc_counter = 0;
> > > > +
> > > > +void *
> > > > +malloc (size_t n)
> > > > +{
> > > > +  PREPARE_MALLOC ();
> > > > +  malloc_counter++;
> > > > +  return __libc_malloc (n);
> > > > +}
> > > > +
> > > > +static void *mod[3];
> > > > +#define MOD(i) "tst-gnu2-tls2mod" #i ".so"
> > > > +static const char *modname[3] = { MOD(0), MOD(1), MOD(2) };
> > > > +#undef MOD
> > > > +
> > > > +static void
> > > > +open_mod (int i)
> > > > +{
> > > > +  mod[i] = xdlopen (modname[i], RTLD_LAZY);
> > > > +  printf ("open %s\n", modname[i]);
> > > > +}
> > > > +
> > > > +static void
> > > > +close_mod (int i)
> > > > +{
> > > > +  xdlclose (mod[i]);
> > > > +  mod[i] = NULL;
> > > > +  printf ("close %s\n", modname[i]);
> > > > +}
> > > > +
> > > > +static void
> > > > +access_mod (int i, const char *sym)
> > > > +{
> > > > +  struct tls var = { -1, -1, -1, -1 };
> > > > +  struct tls *(*f) (struct tls *) = xdlsym (mod[i], sym);
> > > > +  /* Check that our malloc is called.  */
> > > > +  malloc_counter = 0;
> > > > +  struct tls *p = f (&var);
> > > > +  TEST_VERIFY (malloc_counter != 0);
> > > > +  printf ("access %s: %s() = %p\n", modname[i], sym, p);
> > > > +  TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
> > > > +  ++(p->a);
> > > > +}
> > > > +
> > > > +static void *
> > > > +start (void *arg)
> > > > +{
> > > > +  /* The DTV generation is at the last dlopen of mod0 and the
> > > > +     entry for mod1 is NULL.  */
> > > > +
> > > > +  open_mod (1); /* Reuse modid of mod1. Uses dynamic TLS.  */
> > > > +
> > > > +  /* Force the slow path in GNU2 TLS descriptor call.  */
> > > > +  access_mod (1, "apply_tls");
> > > > +
> > > > +  return arg;
> > > > +}
> > > > +
> > > > +static int
> > > > +do_test (void)
> > > > +{
> > > > +  if (!IS_SUPPORTED ())
> > > > +    return EXIT_UNSUPPORTED;
> > > > +
> > > > +  open_mod (0);
> > > > +  open_mod (1);
> > > > +  open_mod (2);
> > > > +  close_mod (0);
> > > > +  close_mod (1); /* Create modid gap at mod1.  */
> > > > +  open_mod (0); /* Reuse modid of mod0, bump generation count.  */
> > > > +
> > > > +  /* Create a thread where DTV of mod1 is NULL.  */
> > > > +  pthread_t t = xpthread_create (NULL, start, NULL);
> > > > +  xpthread_join (t);
> > > > +  return 0;
> > > > +}
> > > > +
> > > > +#include <support/test-driver.c>
> > >
> > > The change looks good but this is still failing on arm.
> > >
> > > ```
> > > FAIL: elf/tst-gnu2-tls2
> > > original exit status 1
> > > open tst-gnu2-tls2mod0.so
> > > open tst-gnu2-tls2mod1.so
> > > open tst-gnu2-tls2mod2.so
> > > close tst-gnu2-tls2mod0.so
> > > close tst-gnu2-tls2mod1.so
> > > open tst-gnu2-tls2mod0.so
> > > open tst-gnu2-tls2mod1.so
> > > Didn't expect signal from child: got `Segmentation fault'
> > > ```
> > >
> > > HJ can you add some more logging to its clear exactly where
> > > the fault is? (looks to be malloc or xdlsym).
> >
> > The new test may fail on targets which don't preserve all
> > caller-saved registers in _dl_tlsdesc_dynamic.
> >
> > > Are there any other arch this is failing on? I.e is this an arm
> > > bug or buggy test?
> > >
> >
> > It is a bug on arm:
> >
> > https://github.com/zatrazz/glibc/commits/azanella/tls-descriptor-fixes-arm/
>
> Is anyone working on a fix for arm?

There is a patch for arm in the URL above:

https://github.com/zatrazz/glibc/commit/acdac4ff394e82ddf348c0eb03a8235ac0f67f7c
Noah Goldstein Feb. 24, 2024, 6:45 p.m. UTC | #5
On Sat, Feb 24, 2024 at 12:00 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Sat, Feb 24, 2024 at 9:39 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >
> > On Sat, Feb 24, 2024 at 11:31 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >
> > > On Sat, Feb 24, 2024 at 9:09 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > > >
> > > > On Fri, Feb 16, 2024 at 9:17 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> > > > >
> > > > > Compiler generates the following instruction sequence for GNU2 dynamic
> > > > > TLS access:
> > > > >
> > > > >         leaq    tls_var@TLSDESC(%rip), %rax
> > > > >         call    *tls_var@TLSCALL(%rax)
> > > > >
> > > > > or
> > > > >
> > > > >         leal    tls_var@TLSDESC(%ebx), %eax
> > > > >         call    *tls_var@TLSCALL(%eax)
> > > > >
> > > > > CALL instruction is transparent to compiler which assumes all registers,
> > > > > except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
> > > > > _dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
> > > > > path.  __tls_get_addr is a normal function which doesn't preserve any
> > > > > caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
> > > > > caller-saved registers, but didn't preserve any other caller-saved
> > > > > registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
> > > > > XSAVE and XSAVEC to save and restore all caller-saved registers.  This
> > > > > fixes BZ #31372.
> > > > >
> > > > > Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
> > > > > to optimize elf_machine_runtime_setup.
> > > > > ---
> > > > >  elf/Makefile                                 |  14 ++
> > > > >  elf/tst-gnu2-tls2.c                          | 120 ++++++++++++
> > > > >  elf/tst-gnu2-tls2.h                          |  36 ++++
> > > > >  elf/tst-gnu2-tls2mod0.c                      |  31 +++
> > > > >  elf/tst-gnu2-tls2mod1.c                      |  31 +++
> > > > >  elf/tst-gnu2-tls2mod2.c                      |  31 +++
> > > > >  sysdeps/i386/dl-machine.h                    |   2 +-
> > > > >  sysdeps/i386/dl-tlsdesc-dynamic.h            | 190 +++++++++++++++++++
> > > > >  sysdeps/i386/dl-tlsdesc.S                    | 115 +++++------
> > > > >  sysdeps/x86/Makefile                         |   7 +-
> > > > >  sysdeps/x86/cpu-features.c                   |  56 +++++-
> > > > >  sysdeps/x86/dl-procinfo.c                    |  16 ++
> > > > >  sysdeps/{x86_64 => x86}/features-offsets.sym |   2 +
> > > > >  sysdeps/x86/sysdep.h                         |   6 +
> > > > >  sysdeps/x86/tst-gnu2-tls2.c                  |  20 ++
> > > > >  sysdeps/x86_64/Makefile                      |   2 +-
> > > > >  sysdeps/x86_64/dl-machine.h                  |  19 +-
> > > > >  sysdeps/x86_64/dl-procinfo.c                 |  16 ++
> > > > >  sysdeps/x86_64/dl-tlsdesc-dynamic.h          | 166 ++++++++++++++++
> > > > >  sysdeps/x86_64/dl-tlsdesc.S                  | 108 ++++-------
> > > > >  sysdeps/x86_64/dl-trampoline-save.h          |  34 ++++
> > > > >  sysdeps/x86_64/dl-trampoline-state.h         |  51 +++++
> > > > >  sysdeps/x86_64/dl-trampoline.S               |  20 +-
> > > > >  sysdeps/x86_64/dl-trampoline.h               |  34 +---
> > > > >  24 files changed, 914 insertions(+), 213 deletions(-)
> > > > >  create mode 100644 elf/tst-gnu2-tls2.c
> > > > >  create mode 100644 elf/tst-gnu2-tls2.h
> > > > >  create mode 100644 elf/tst-gnu2-tls2mod0.c
> > > > >  create mode 100644 elf/tst-gnu2-tls2mod1.c
> > > > >  create mode 100644 elf/tst-gnu2-tls2mod2.c
> > > > >  create mode 100644 sysdeps/i386/dl-tlsdesc-dynamic.h
> > > > >  rename sysdeps/{x86_64 => x86}/features-offsets.sym (89%)
> > > > >  create mode 100644 sysdeps/x86/tst-gnu2-tls2.c
> > > > >  create mode 100644 sysdeps/x86_64/dl-tlsdesc-dynamic.h
> > > > >  create mode 100644 sysdeps/x86_64/dl-trampoline-save.h
> > > > >  create mode 100644 sysdeps/x86_64/dl-trampoline-state.h
> > > > >
> > > > > diff --git a/elf/Makefile b/elf/Makefile
> > > > > index 5d78b659ce..030db4d207 100644
> > > > > --- a/elf/Makefile
> > > > > +++ b/elf/Makefile
> > > > > @@ -424,6 +424,7 @@ tests += \
> > > > >    tst-glibc-hwcaps-prepend \
> > > > >    tst-global1 \
> > > > >    tst-global2 \
> > > > > +  tst-gnu2-tls2 \
> > > > >    tst-initfinilazyfail \
> > > > >    tst-initorder \
> > > > >    tst-initorder2 \
> > > > > @@ -846,6 +847,9 @@ modules-names += \
> > > > >    tst-filterobj-flt \
> > > > >    tst-finilazyfailmod \
> > > > >    tst-globalmod2 \
> > > > > +  tst-gnu2-tls2mod0 \
> > > > > +  tst-gnu2-tls2mod1 \
> > > > > +  tst-gnu2-tls2mod2 \
> > > > >    tst-initlazyfailmod \
> > > > >    tst-initorder2a \
> > > > >    tst-initorder2b \
> > > > > @@ -3044,8 +3048,18 @@ $(objpfx)tst-tlsgap.out: \
> > > > >    $(objpfx)tst-tlsgap-mod0.so \
> > > > >    $(objpfx)tst-tlsgap-mod1.so \
> > > > >    $(objpfx)tst-tlsgap-mod2.so
> > > > > +
> > > > > +$(objpfx)tst-gnu2-tls2: $(shared-thread-library)
> > > > > +$(objpfx)tst-gnu2-tls2.out: \
> > > > > +  $(objpfx)tst-gnu2-tls2mod0.so \
> > > > > +  $(objpfx)tst-gnu2-tls2mod1.so \
> > > > > +  $(objpfx)tst-gnu2-tls2mod2.so
> > > > > +
> > > > >  ifeq (yes,$(have-mtls-dialect-gnu2))
> > > > >  CFLAGS-tst-tlsgap-mod0.c += -mtls-dialect=gnu2
> > > > >  CFLAGS-tst-tlsgap-mod1.c += -mtls-dialect=gnu2
> > > > >  CFLAGS-tst-tlsgap-mod2.c += -mtls-dialect=gnu2
> > > > > +CFLAGS-tst-gnu2-tls2mod0.c += -mtls-dialect=gnu2
> > > > > +CFLAGS-tst-gnu2-tls2mod1.c += -mtls-dialect=gnu2
> > > > > +CFLAGS-tst-gnu2-tls2mod2.c += -mtls-dialect=gnu2
> > > > >  endif
> > > > > diff --git a/elf/tst-gnu2-tls2.c b/elf/tst-gnu2-tls2.c
> > > > > new file mode 100644
> > > > > index 0000000000..8039ba614d
> > > > > --- /dev/null
> > > > > +++ b/elf/tst-gnu2-tls2.c
> > > > > @@ -0,0 +1,120 @@
> > > > > +/* Test TLSDESC relocation.
> > > > > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > > > > +   This file is part of the GNU C Library.
> > > > > +
> > > > > +   The GNU C Library is free software; you can redistribute it and/or
> > > > > +   modify it under the terms of the GNU Lesser General Public
> > > > > +   License as published by the Free Software Foundation; either
> > > > > +   version 2.1 of the License, or (at your option) any later version.
> > > > > +
> > > > > +   The GNU C Library is distributed in the hope that it will be useful,
> > > > > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > > > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > > > > +   Lesser General Public License for more details.
> > > > > +
> > > > > +   You should have received a copy of the GNU Lesser General Public
> > > > > +   License along with the GNU C Library; if not, see
> > > > > +   <http://www.gnu.org/licenses/>.  */
> > > > > +
> > > > > +#include <stdio.h>
> > > > > +#include <stdlib.h>
> > > > > +#include <string.h>
> > > > > +#include <dlfcn.h>
> > > > > +#include <pthread.h>
> > > > > +#include <support/xdlfcn.h>
> > > > > +#include <support/xthread.h>
> > > > > +#include <support/check.h>
> > > > > +#include <support/test-driver.h>
> > > > > +#include "tst-gnu2-tls2.h"
> > > > > +
> > > > > +#ifndef IS_SUPPORTED
> > > > > +# define IS_SUPPORTED() true
> > > > > +#endif
> > > > > +
> > > > > +/* An architecture can define it to clobber caller-saved registers in
> > > > > +   malloc below to verify that the implicit TLSDESC call won't change
> > > > > +   caller-saved registers.  */
> > > > > +#ifndef PREPARE_MALLOC
> > > > > +# define PREPARE_MALLOC()
> > > > > +#endif
> > > > > +
> > > > > +extern void * __libc_malloc (size_t);
> > > > > +
> > > > > +size_t malloc_counter = 0;
> > > > > +
> > > > > +void *
> > > > > +malloc (size_t n)
> > > > > +{
> > > > > +  PREPARE_MALLOC ();
> > > > > +  malloc_counter++;
> > > > > +  return __libc_malloc (n);
> > > > > +}
> > > > > +
> > > > > +static void *mod[3];
> > > > > +#define MOD(i) "tst-gnu2-tls2mod" #i ".so"
> > > > > +static const char *modname[3] = { MOD(0), MOD(1), MOD(2) };
> > > > > +#undef MOD
> > > > > +
> > > > > +static void
> > > > > +open_mod (int i)
> > > > > +{
> > > > > +  mod[i] = xdlopen (modname[i], RTLD_LAZY);
> > > > > +  printf ("open %s\n", modname[i]);
> > > > > +}
> > > > > +
> > > > > +static void
> > > > > +close_mod (int i)
> > > > > +{
> > > > > +  xdlclose (mod[i]);
> > > > > +  mod[i] = NULL;
> > > > > +  printf ("close %s\n", modname[i]);
> > > > > +}
> > > > > +
> > > > > +static void
> > > > > +access_mod (int i, const char *sym)
> > > > > +{
> > > > > +  struct tls var = { -1, -1, -1, -1 };
> > > > > +  struct tls *(*f) (struct tls *) = xdlsym (mod[i], sym);
> > > > > +  /* Check that our malloc is called.  */
> > > > > +  malloc_counter = 0;
> > > > > +  struct tls *p = f (&var);
> > > > > +  TEST_VERIFY (malloc_counter != 0);
> > > > > +  printf ("access %s: %s() = %p\n", modname[i], sym, p);
> > > > > +  TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
> > > > > +  ++(p->a);
> > > > > +}
> > > > > +
> > > > > +static void *
> > > > > +start (void *arg)
> > > > > +{
> > > > > +  /* The DTV generation is at the last dlopen of mod0 and the
> > > > > +     entry for mod1 is NULL.  */
> > > > > +
> > > > > +  open_mod (1); /* Reuse modid of mod1. Uses dynamic TLS.  */
> > > > > +
> > > > > +  /* Force the slow path in GNU2 TLS descriptor call.  */
> > > > > +  access_mod (1, "apply_tls");
> > > > > +
> > > > > +  return arg;
> > > > > +}
> > > > > +
> > > > > +static int
> > > > > +do_test (void)
> > > > > +{
> > > > > +  if (!IS_SUPPORTED ())
> > > > > +    return EXIT_UNSUPPORTED;
> > > > > +
> > > > > +  open_mod (0);
> > > > > +  open_mod (1);
> > > > > +  open_mod (2);
> > > > > +  close_mod (0);
> > > > > +  close_mod (1); /* Create modid gap at mod1.  */
> > > > > +  open_mod (0); /* Reuse modid of mod0, bump generation count.  */
> > > > > +
> > > > > +  /* Create a thread where DTV of mod1 is NULL.  */
> > > > > +  pthread_t t = xpthread_create (NULL, start, NULL);
> > > > > +  xpthread_join (t);
> > > > > +  return 0;
> > > > > +}
> > > > > +
> > > > > +#include <support/test-driver.c>
> > > >
> > > > The change looks good but this is still failing on arm.
> > > >
> > > > ```
> > > > FAIL: elf/tst-gnu2-tls2
> > > > original exit status 1
> > > > open tst-gnu2-tls2mod0.so
> > > > open tst-gnu2-tls2mod1.so
> > > > open tst-gnu2-tls2mod2.so
> > > > close tst-gnu2-tls2mod0.so
> > > > close tst-gnu2-tls2mod1.so
> > > > open tst-gnu2-tls2mod0.so
> > > > open tst-gnu2-tls2mod1.so
> > > > Didn't expect signal from child: got `Segmentation fault'
> > > > ```
> > > >
> > > > HJ can you add some more logging to its clear exactly where
> > > > the fault is? (looks to be malloc or xdlsym).
> > >
> > > The new test may fail on targets which don't preserve all
> > > caller-saved registers in _dl_tlsdesc_dynamic.
> > >
> > > > Are there any other arch this is failing on? I.e is this an arm
> > > > bug or buggy test?
> > > >
> > >
> > > It is a bug on arm:
> > >
> > > https://github.com/zatrazz/glibc/commits/azanella/tls-descriptor-fixes-arm/
> >
> > Is anyone working on a fix for arm?
>
> There is a patch for arm in the URL above:
>
> https://github.com/zatrazz/glibc/commit/acdac4ff394e82ddf348c0eb03a8235ac0f67f7c
>

Can you re-submit the patch to make the CI happy?
> --
> H.J.
H.J. Lu Feb. 24, 2024, 6:52 p.m. UTC | #6
On Sat, Feb 24, 2024 at 10:45 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Sat, Feb 24, 2024 at 12:00 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Sat, Feb 24, 2024 at 9:39 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > >
> > > On Sat, Feb 24, 2024 at 11:31 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> > > >
> > > > On Sat, Feb 24, 2024 at 9:09 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > > > >
> > > > > On Fri, Feb 16, 2024 at 9:17 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> > > > > >
> > > > > > Compiler generates the following instruction sequence for GNU2 dynamic
> > > > > > TLS access:
> > > > > >
> > > > > >         leaq    tls_var@TLSDESC(%rip), %rax
> > > > > >         call    *tls_var@TLSCALL(%rax)
> > > > > >
> > > > > > or
> > > > > >
> > > > > >         leal    tls_var@TLSDESC(%ebx), %eax
> > > > > >         call    *tls_var@TLSCALL(%eax)
> > > > > >
> > > > > > CALL instruction is transparent to compiler which assumes all registers,
> > > > > > except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
> > > > > > _dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
> > > > > > path.  __tls_get_addr is a normal function which doesn't preserve any
> > > > > > caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
> > > > > > caller-saved registers, but didn't preserve any other caller-saved
> > > > > > registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
> > > > > > XSAVE and XSAVEC to save and restore all caller-saved registers.  This
> > > > > > fixes BZ #31372.
> > > > > >
> > > > > > Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
> > > > > > to optimize elf_machine_runtime_setup.
> > > > > > ---
> > > > > >  elf/Makefile                                 |  14 ++
> > > > > >  elf/tst-gnu2-tls2.c                          | 120 ++++++++++++
> > > > > >  elf/tst-gnu2-tls2.h                          |  36 ++++
> > > > > >  elf/tst-gnu2-tls2mod0.c                      |  31 +++
> > > > > >  elf/tst-gnu2-tls2mod1.c                      |  31 +++
> > > > > >  elf/tst-gnu2-tls2mod2.c                      |  31 +++
> > > > > >  sysdeps/i386/dl-machine.h                    |   2 +-
> > > > > >  sysdeps/i386/dl-tlsdesc-dynamic.h            | 190 +++++++++++++++++++
> > > > > >  sysdeps/i386/dl-tlsdesc.S                    | 115 +++++------
> > > > > >  sysdeps/x86/Makefile                         |   7 +-
> > > > > >  sysdeps/x86/cpu-features.c                   |  56 +++++-
> > > > > >  sysdeps/x86/dl-procinfo.c                    |  16 ++
> > > > > >  sysdeps/{x86_64 => x86}/features-offsets.sym |   2 +
> > > > > >  sysdeps/x86/sysdep.h                         |   6 +
> > > > > >  sysdeps/x86/tst-gnu2-tls2.c                  |  20 ++
> > > > > >  sysdeps/x86_64/Makefile                      |   2 +-
> > > > > >  sysdeps/x86_64/dl-machine.h                  |  19 +-
> > > > > >  sysdeps/x86_64/dl-procinfo.c                 |  16 ++
> > > > > >  sysdeps/x86_64/dl-tlsdesc-dynamic.h          | 166 ++++++++++++++++
> > > > > >  sysdeps/x86_64/dl-tlsdesc.S                  | 108 ++++-------
> > > > > >  sysdeps/x86_64/dl-trampoline-save.h          |  34 ++++
> > > > > >  sysdeps/x86_64/dl-trampoline-state.h         |  51 +++++
> > > > > >  sysdeps/x86_64/dl-trampoline.S               |  20 +-
> > > > > >  sysdeps/x86_64/dl-trampoline.h               |  34 +---
> > > > > >  24 files changed, 914 insertions(+), 213 deletions(-)
> > > > > >  create mode 100644 elf/tst-gnu2-tls2.c
> > > > > >  create mode 100644 elf/tst-gnu2-tls2.h
> > > > > >  create mode 100644 elf/tst-gnu2-tls2mod0.c
> > > > > >  create mode 100644 elf/tst-gnu2-tls2mod1.c
> > > > > >  create mode 100644 elf/tst-gnu2-tls2mod2.c
> > > > > >  create mode 100644 sysdeps/i386/dl-tlsdesc-dynamic.h
> > > > > >  rename sysdeps/{x86_64 => x86}/features-offsets.sym (89%)
> > > > > >  create mode 100644 sysdeps/x86/tst-gnu2-tls2.c
> > > > > >  create mode 100644 sysdeps/x86_64/dl-tlsdesc-dynamic.h
> > > > > >  create mode 100644 sysdeps/x86_64/dl-trampoline-save.h
> > > > > >  create mode 100644 sysdeps/x86_64/dl-trampoline-state.h
> > > > > >
> > > > > > diff --git a/elf/Makefile b/elf/Makefile
> > > > > > index 5d78b659ce..030db4d207 100644
> > > > > > --- a/elf/Makefile
> > > > > > +++ b/elf/Makefile
> > > > > > @@ -424,6 +424,7 @@ tests += \
> > > > > >    tst-glibc-hwcaps-prepend \
> > > > > >    tst-global1 \
> > > > > >    tst-global2 \
> > > > > > +  tst-gnu2-tls2 \
> > > > > >    tst-initfinilazyfail \
> > > > > >    tst-initorder \
> > > > > >    tst-initorder2 \
> > > > > > @@ -846,6 +847,9 @@ modules-names += \
> > > > > >    tst-filterobj-flt \
> > > > > >    tst-finilazyfailmod \
> > > > > >    tst-globalmod2 \
> > > > > > +  tst-gnu2-tls2mod0 \
> > > > > > +  tst-gnu2-tls2mod1 \
> > > > > > +  tst-gnu2-tls2mod2 \
> > > > > >    tst-initlazyfailmod \
> > > > > >    tst-initorder2a \
> > > > > >    tst-initorder2b \
> > > > > > @@ -3044,8 +3048,18 @@ $(objpfx)tst-tlsgap.out: \
> > > > > >    $(objpfx)tst-tlsgap-mod0.so \
> > > > > >    $(objpfx)tst-tlsgap-mod1.so \
> > > > > >    $(objpfx)tst-tlsgap-mod2.so
> > > > > > +
> > > > > > +$(objpfx)tst-gnu2-tls2: $(shared-thread-library)
> > > > > > +$(objpfx)tst-gnu2-tls2.out: \
> > > > > > +  $(objpfx)tst-gnu2-tls2mod0.so \
> > > > > > +  $(objpfx)tst-gnu2-tls2mod1.so \
> > > > > > +  $(objpfx)tst-gnu2-tls2mod2.so
> > > > > > +
> > > > > >  ifeq (yes,$(have-mtls-dialect-gnu2))
> > > > > >  CFLAGS-tst-tlsgap-mod0.c += -mtls-dialect=gnu2
> > > > > >  CFLAGS-tst-tlsgap-mod1.c += -mtls-dialect=gnu2
> > > > > >  CFLAGS-tst-tlsgap-mod2.c += -mtls-dialect=gnu2
> > > > > > +CFLAGS-tst-gnu2-tls2mod0.c += -mtls-dialect=gnu2
> > > > > > +CFLAGS-tst-gnu2-tls2mod1.c += -mtls-dialect=gnu2
> > > > > > +CFLAGS-tst-gnu2-tls2mod2.c += -mtls-dialect=gnu2
> > > > > >  endif
> > > > > > diff --git a/elf/tst-gnu2-tls2.c b/elf/tst-gnu2-tls2.c
> > > > > > new file mode 100644
> > > > > > index 0000000000..8039ba614d
> > > > > > --- /dev/null
> > > > > > +++ b/elf/tst-gnu2-tls2.c
> > > > > > @@ -0,0 +1,120 @@
> > > > > > +/* Test TLSDESC relocation.
> > > > > > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > > > > > +   This file is part of the GNU C Library.
> > > > > > +
> > > > > > +   The GNU C Library is free software; you can redistribute it and/or
> > > > > > +   modify it under the terms of the GNU Lesser General Public
> > > > > > +   License as published by the Free Software Foundation; either
> > > > > > +   version 2.1 of the License, or (at your option) any later version.
> > > > > > +
> > > > > > +   The GNU C Library is distributed in the hope that it will be useful,
> > > > > > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > > > > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > > > > > +   Lesser General Public License for more details.
> > > > > > +
> > > > > > +   You should have received a copy of the GNU Lesser General Public
> > > > > > +   License along with the GNU C Library; if not, see
> > > > > > +   <http://www.gnu.org/licenses/>.  */
> > > > > > +
> > > > > > +#include <stdio.h>
> > > > > > +#include <stdlib.h>
> > > > > > +#include <string.h>
> > > > > > +#include <dlfcn.h>
> > > > > > +#include <pthread.h>
> > > > > > +#include <support/xdlfcn.h>
> > > > > > +#include <support/xthread.h>
> > > > > > +#include <support/check.h>
> > > > > > +#include <support/test-driver.h>
> > > > > > +#include "tst-gnu2-tls2.h"
> > > > > > +
> > > > > > +#ifndef IS_SUPPORTED
> > > > > > +# define IS_SUPPORTED() true
> > > > > > +#endif
> > > > > > +
> > > > > > +/* An architecture can define it to clobber caller-saved registers in
> > > > > > +   malloc below to verify that the implicit TLSDESC call won't change
> > > > > > +   caller-saved registers.  */
> > > > > > +#ifndef PREPARE_MALLOC
> > > > > > +# define PREPARE_MALLOC()
> > > > > > +#endif
> > > > > > +
> > > > > > +extern void * __libc_malloc (size_t);
> > > > > > +
> > > > > > +size_t malloc_counter = 0;
> > > > > > +
> > > > > > +void *
> > > > > > +malloc (size_t n)
> > > > > > +{
> > > > > > +  PREPARE_MALLOC ();
> > > > > > +  malloc_counter++;
> > > > > > +  return __libc_malloc (n);
> > > > > > +}
> > > > > > +
> > > > > > +static void *mod[3];
> > > > > > +#define MOD(i) "tst-gnu2-tls2mod" #i ".so"
> > > > > > +static const char *modname[3] = { MOD(0), MOD(1), MOD(2) };
> > > > > > +#undef MOD
> > > > > > +
> > > > > > +static void
> > > > > > +open_mod (int i)
> > > > > > +{
> > > > > > +  mod[i] = xdlopen (modname[i], RTLD_LAZY);
> > > > > > +  printf ("open %s\n", modname[i]);
> > > > > > +}
> > > > > > +
> > > > > > +static void
> > > > > > +close_mod (int i)
> > > > > > +{
> > > > > > +  xdlclose (mod[i]);
> > > > > > +  mod[i] = NULL;
> > > > > > +  printf ("close %s\n", modname[i]);
> > > > > > +}
> > > > > > +
> > > > > > +static void
> > > > > > +access_mod (int i, const char *sym)
> > > > > > +{
> > > > > > +  struct tls var = { -1, -1, -1, -1 };
> > > > > > +  struct tls *(*f) (struct tls *) = xdlsym (mod[i], sym);
> > > > > > +  /* Check that our malloc is called.  */
> > > > > > +  malloc_counter = 0;
> > > > > > +  struct tls *p = f (&var);
> > > > > > +  TEST_VERIFY (malloc_counter != 0);
> > > > > > +  printf ("access %s: %s() = %p\n", modname[i], sym, p);
> > > > > > +  TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
> > > > > > +  ++(p->a);
> > > > > > +}
> > > > > > +
> > > > > > +static void *
> > > > > > +start (void *arg)
> > > > > > +{
> > > > > > +  /* The DTV generation is at the last dlopen of mod0 and the
> > > > > > +     entry for mod1 is NULL.  */
> > > > > > +
> > > > > > +  open_mod (1); /* Reuse modid of mod1. Uses dynamic TLS.  */
> > > > > > +
> > > > > > +  /* Force the slow path in GNU2 TLS descriptor call.  */
> > > > > > +  access_mod (1, "apply_tls");
> > > > > > +
> > > > > > +  return arg;
> > > > > > +}
> > > > > > +
> > > > > > +static int
> > > > > > +do_test (void)
> > > > > > +{
> > > > > > +  if (!IS_SUPPORTED ())
> > > > > > +    return EXIT_UNSUPPORTED;
> > > > > > +
> > > > > > +  open_mod (0);
> > > > > > +  open_mod (1);
> > > > > > +  open_mod (2);
> > > > > > +  close_mod (0);
> > > > > > +  close_mod (1); /* Create modid gap at mod1.  */
> > > > > > +  open_mod (0); /* Reuse modid of mod0, bump generation count.  */
> > > > > > +
> > > > > > +  /* Create a thread where DTV of mod1 is NULL.  */
> > > > > > +  pthread_t t = xpthread_create (NULL, start, NULL);
> > > > > > +  xpthread_join (t);
> > > > > > +  return 0;
> > > > > > +}
> > > > > > +
> > > > > > +#include <support/test-driver.c>
> > > > >
> > > > > The change looks good but this is still failing on arm.
> > > > >
> > > > > ```
> > > > > FAIL: elf/tst-gnu2-tls2
> > > > > original exit status 1
> > > > > open tst-gnu2-tls2mod0.so
> > > > > open tst-gnu2-tls2mod1.so
> > > > > open tst-gnu2-tls2mod2.so
> > > > > close tst-gnu2-tls2mod0.so
> > > > > close tst-gnu2-tls2mod1.so
> > > > > open tst-gnu2-tls2mod0.so
> > > > > open tst-gnu2-tls2mod1.so
> > > > > Didn't expect signal from child: got `Segmentation fault'
> > > > > ```
> > > > >
> > > > > HJ can you add some more logging to its clear exactly where
> > > > > the fault is? (looks to be malloc or xdlsym).
> > > >
> > > > The new test may fail on targets which don't preserve all
> > > > caller-saved registers in _dl_tlsdesc_dynamic.
> > > >
> > > > > Are there any other arch this is failing on? I.e is this an arm
> > > > > bug or buggy test?
> > > > >
> > > >
> > > > It is a bug on arm:
> > > >
> > > > https://github.com/zatrazz/glibc/commits/azanella/tls-descriptor-fixes-arm/
> > >
> > > Is anyone working on a fix for arm?
> >
> > There is a patch for arm in the URL above:
> >
> > https://github.com/zatrazz/glibc/commit/acdac4ff394e82ddf348c0eb03a8235ac0f67f7c
> >
>
> Can you re-submit the patch to make the CI happy?

That is Adhemerval's patch.  I prefer letting him decide what
to do.  My patch doesn't change any target files.  I can make
the new testcase x86 specific.  But I don't believe that we should
make CI happy in this particular case.
Noah Goldstein Feb. 24, 2024, 6:59 p.m. UTC | #7
On Sat, Feb 24, 2024 at 12:52 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Sat, Feb 24, 2024 at 10:45 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >
> > On Sat, Feb 24, 2024 at 12:00 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >
> > > On Sat, Feb 24, 2024 at 9:39 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > > >
> > > > On Sat, Feb 24, 2024 at 11:31 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> > > > >
> > > > > On Sat, Feb 24, 2024 at 9:09 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > > > > >
> > > > > > On Fri, Feb 16, 2024 at 9:17 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> > > > > > >
> > > > > > > Compiler generates the following instruction sequence for GNU2 dynamic
> > > > > > > TLS access:
> > > > > > >
> > > > > > >         leaq    tls_var@TLSDESC(%rip), %rax
> > > > > > >         call    *tls_var@TLSCALL(%rax)
> > > > > > >
> > > > > > > or
> > > > > > >
> > > > > > >         leal    tls_var@TLSDESC(%ebx), %eax
> > > > > > >         call    *tls_var@TLSCALL(%eax)
> > > > > > >
> > > > > > > CALL instruction is transparent to compiler which assumes all registers,
> > > > > > > except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
> > > > > > > _dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
> > > > > > > path.  __tls_get_addr is a normal function which doesn't preserve any
> > > > > > > caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
> > > > > > > caller-saved registers, but didn't preserve any other caller-saved
> > > > > > > registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
> > > > > > > XSAVE and XSAVEC to save and restore all caller-saved registers.  This
> > > > > > > fixes BZ #31372.
> > > > > > >
> > > > > > > Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
> > > > > > > to optimize elf_machine_runtime_setup.
> > > > > > > ---
> > > > > > >  elf/Makefile                                 |  14 ++
> > > > > > >  elf/tst-gnu2-tls2.c                          | 120 ++++++++++++
> > > > > > >  elf/tst-gnu2-tls2.h                          |  36 ++++
> > > > > > >  elf/tst-gnu2-tls2mod0.c                      |  31 +++
> > > > > > >  elf/tst-gnu2-tls2mod1.c                      |  31 +++
> > > > > > >  elf/tst-gnu2-tls2mod2.c                      |  31 +++
> > > > > > >  sysdeps/i386/dl-machine.h                    |   2 +-
> > > > > > >  sysdeps/i386/dl-tlsdesc-dynamic.h            | 190 +++++++++++++++++++
> > > > > > >  sysdeps/i386/dl-tlsdesc.S                    | 115 +++++------
> > > > > > >  sysdeps/x86/Makefile                         |   7 +-
> > > > > > >  sysdeps/x86/cpu-features.c                   |  56 +++++-
> > > > > > >  sysdeps/x86/dl-procinfo.c                    |  16 ++
> > > > > > >  sysdeps/{x86_64 => x86}/features-offsets.sym |   2 +
> > > > > > >  sysdeps/x86/sysdep.h                         |   6 +
> > > > > > >  sysdeps/x86/tst-gnu2-tls2.c                  |  20 ++
> > > > > > >  sysdeps/x86_64/Makefile                      |   2 +-
> > > > > > >  sysdeps/x86_64/dl-machine.h                  |  19 +-
> > > > > > >  sysdeps/x86_64/dl-procinfo.c                 |  16 ++
> > > > > > >  sysdeps/x86_64/dl-tlsdesc-dynamic.h          | 166 ++++++++++++++++
> > > > > > >  sysdeps/x86_64/dl-tlsdesc.S                  | 108 ++++-------
> > > > > > >  sysdeps/x86_64/dl-trampoline-save.h          |  34 ++++
> > > > > > >  sysdeps/x86_64/dl-trampoline-state.h         |  51 +++++
> > > > > > >  sysdeps/x86_64/dl-trampoline.S               |  20 +-
> > > > > > >  sysdeps/x86_64/dl-trampoline.h               |  34 +---
> > > > > > >  24 files changed, 914 insertions(+), 213 deletions(-)
> > > > > > >  create mode 100644 elf/tst-gnu2-tls2.c
> > > > > > >  create mode 100644 elf/tst-gnu2-tls2.h
> > > > > > >  create mode 100644 elf/tst-gnu2-tls2mod0.c
> > > > > > >  create mode 100644 elf/tst-gnu2-tls2mod1.c
> > > > > > >  create mode 100644 elf/tst-gnu2-tls2mod2.c
> > > > > > >  create mode 100644 sysdeps/i386/dl-tlsdesc-dynamic.h
> > > > > > >  rename sysdeps/{x86_64 => x86}/features-offsets.sym (89%)
> > > > > > >  create mode 100644 sysdeps/x86/tst-gnu2-tls2.c
> > > > > > >  create mode 100644 sysdeps/x86_64/dl-tlsdesc-dynamic.h
> > > > > > >  create mode 100644 sysdeps/x86_64/dl-trampoline-save.h
> > > > > > >  create mode 100644 sysdeps/x86_64/dl-trampoline-state.h
> > > > > > >
> > > > > > > diff --git a/elf/Makefile b/elf/Makefile
> > > > > > > index 5d78b659ce..030db4d207 100644
> > > > > > > --- a/elf/Makefile
> > > > > > > +++ b/elf/Makefile
> > > > > > > @@ -424,6 +424,7 @@ tests += \
> > > > > > >    tst-glibc-hwcaps-prepend \
> > > > > > >    tst-global1 \
> > > > > > >    tst-global2 \
> > > > > > > +  tst-gnu2-tls2 \
> > > > > > >    tst-initfinilazyfail \
> > > > > > >    tst-initorder \
> > > > > > >    tst-initorder2 \
> > > > > > > @@ -846,6 +847,9 @@ modules-names += \
> > > > > > >    tst-filterobj-flt \
> > > > > > >    tst-finilazyfailmod \
> > > > > > >    tst-globalmod2 \
> > > > > > > +  tst-gnu2-tls2mod0 \
> > > > > > > +  tst-gnu2-tls2mod1 \
> > > > > > > +  tst-gnu2-tls2mod2 \
> > > > > > >    tst-initlazyfailmod \
> > > > > > >    tst-initorder2a \
> > > > > > >    tst-initorder2b \
> > > > > > > @@ -3044,8 +3048,18 @@ $(objpfx)tst-tlsgap.out: \
> > > > > > >    $(objpfx)tst-tlsgap-mod0.so \
> > > > > > >    $(objpfx)tst-tlsgap-mod1.so \
> > > > > > >    $(objpfx)tst-tlsgap-mod2.so
> > > > > > > +
> > > > > > > +$(objpfx)tst-gnu2-tls2: $(shared-thread-library)
> > > > > > > +$(objpfx)tst-gnu2-tls2.out: \
> > > > > > > +  $(objpfx)tst-gnu2-tls2mod0.so \
> > > > > > > +  $(objpfx)tst-gnu2-tls2mod1.so \
> > > > > > > +  $(objpfx)tst-gnu2-tls2mod2.so
> > > > > > > +
> > > > > > >  ifeq (yes,$(have-mtls-dialect-gnu2))
> > > > > > >  CFLAGS-tst-tlsgap-mod0.c += -mtls-dialect=gnu2
> > > > > > >  CFLAGS-tst-tlsgap-mod1.c += -mtls-dialect=gnu2
> > > > > > >  CFLAGS-tst-tlsgap-mod2.c += -mtls-dialect=gnu2
> > > > > > > +CFLAGS-tst-gnu2-tls2mod0.c += -mtls-dialect=gnu2
> > > > > > > +CFLAGS-tst-gnu2-tls2mod1.c += -mtls-dialect=gnu2
> > > > > > > +CFLAGS-tst-gnu2-tls2mod2.c += -mtls-dialect=gnu2
> > > > > > >  endif
> > > > > > > diff --git a/elf/tst-gnu2-tls2.c b/elf/tst-gnu2-tls2.c
> > > > > > > new file mode 100644
> > > > > > > index 0000000000..8039ba614d
> > > > > > > --- /dev/null
> > > > > > > +++ b/elf/tst-gnu2-tls2.c
> > > > > > > @@ -0,0 +1,120 @@
> > > > > > > +/* Test TLSDESC relocation.
> > > > > > > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > > > > > > +   This file is part of the GNU C Library.
> > > > > > > +
> > > > > > > +   The GNU C Library is free software; you can redistribute it and/or
> > > > > > > +   modify it under the terms of the GNU Lesser General Public
> > > > > > > +   License as published by the Free Software Foundation; either
> > > > > > > +   version 2.1 of the License, or (at your option) any later version.
> > > > > > > +
> > > > > > > +   The GNU C Library is distributed in the hope that it will be useful,
> > > > > > > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > > > > > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > > > > > > +   Lesser General Public License for more details.
> > > > > > > +
> > > > > > > +   You should have received a copy of the GNU Lesser General Public
> > > > > > > +   License along with the GNU C Library; if not, see
> > > > > > > +   <http://www.gnu.org/licenses/>.  */
> > > > > > > +
> > > > > > > +#include <stdio.h>
> > > > > > > +#include <stdlib.h>
> > > > > > > +#include <string.h>
> > > > > > > +#include <dlfcn.h>
> > > > > > > +#include <pthread.h>
> > > > > > > +#include <support/xdlfcn.h>
> > > > > > > +#include <support/xthread.h>
> > > > > > > +#include <support/check.h>
> > > > > > > +#include <support/test-driver.h>
> > > > > > > +#include "tst-gnu2-tls2.h"
> > > > > > > +
> > > > > > > +#ifndef IS_SUPPORTED
> > > > > > > +# define IS_SUPPORTED() true
> > > > > > > +#endif
> > > > > > > +
> > > > > > > +/* An architecture can define it to clobber caller-saved registers in
> > > > > > > +   malloc below to verify that the implicit TLSDESC call won't change
> > > > > > > +   caller-saved registers.  */
> > > > > > > +#ifndef PREPARE_MALLOC
> > > > > > > +# define PREPARE_MALLOC()
> > > > > > > +#endif
> > > > > > > +
> > > > > > > +extern void * __libc_malloc (size_t);
> > > > > > > +
> > > > > > > +size_t malloc_counter = 0;
> > > > > > > +
> > > > > > > +void *
> > > > > > > +malloc (size_t n)
> > > > > > > +{
> > > > > > > +  PREPARE_MALLOC ();
> > > > > > > +  malloc_counter++;
> > > > > > > +  return __libc_malloc (n);
> > > > > > > +}
> > > > > > > +
> > > > > > > +static void *mod[3];
> > > > > > > +#define MOD(i) "tst-gnu2-tls2mod" #i ".so"
> > > > > > > +static const char *modname[3] = { MOD(0), MOD(1), MOD(2) };
> > > > > > > +#undef MOD
> > > > > > > +
> > > > > > > +static void
> > > > > > > +open_mod (int i)
> > > > > > > +{
> > > > > > > +  mod[i] = xdlopen (modname[i], RTLD_LAZY);
> > > > > > > +  printf ("open %s\n", modname[i]);
> > > > > > > +}
> > > > > > > +
> > > > > > > +static void
> > > > > > > +close_mod (int i)
> > > > > > > +{
> > > > > > > +  xdlclose (mod[i]);
> > > > > > > +  mod[i] = NULL;
> > > > > > > +  printf ("close %s\n", modname[i]);
> > > > > > > +}
> > > > > > > +
> > > > > > > +static void
> > > > > > > +access_mod (int i, const char *sym)
> > > > > > > +{
> > > > > > > +  struct tls var = { -1, -1, -1, -1 };
> > > > > > > +  struct tls *(*f) (struct tls *) = xdlsym (mod[i], sym);
> > > > > > > +  /* Check that our malloc is called.  */
> > > > > > > +  malloc_counter = 0;
> > > > > > > +  struct tls *p = f (&var);
> > > > > > > +  TEST_VERIFY (malloc_counter != 0);
> > > > > > > +  printf ("access %s: %s() = %p\n", modname[i], sym, p);
> > > > > > > +  TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
> > > > > > > +  ++(p->a);
> > > > > > > +}
> > > > > > > +
> > > > > > > +static void *
> > > > > > > +start (void *arg)
> > > > > > > +{
> > > > > > > +  /* The DTV generation is at the last dlopen of mod0 and the
> > > > > > > +     entry for mod1 is NULL.  */
> > > > > > > +
> > > > > > > +  open_mod (1); /* Reuse modid of mod1. Uses dynamic TLS.  */
> > > > > > > +
> > > > > > > +  /* Force the slow path in GNU2 TLS descriptor call.  */
> > > > > > > +  access_mod (1, "apply_tls");
> > > > > > > +
> > > > > > > +  return arg;
> > > > > > > +}
> > > > > > > +
> > > > > > > +static int
> > > > > > > +do_test (void)
> > > > > > > +{
> > > > > > > +  if (!IS_SUPPORTED ())
> > > > > > > +    return EXIT_UNSUPPORTED;
> > > > > > > +
> > > > > > > +  open_mod (0);
> > > > > > > +  open_mod (1);
> > > > > > > +  open_mod (2);
> > > > > > > +  close_mod (0);
> > > > > > > +  close_mod (1); /* Create modid gap at mod1.  */
> > > > > > > +  open_mod (0); /* Reuse modid of mod0, bump generation count.  */
> > > > > > > +
> > > > > > > +  /* Create a thread where DTV of mod1 is NULL.  */
> > > > > > > +  pthread_t t = xpthread_create (NULL, start, NULL);
> > > > > > > +  xpthread_join (t);
> > > > > > > +  return 0;
> > > > > > > +}
> > > > > > > +
> > > > > > > +#include <support/test-driver.c>
> > > > > >
> > > > > > The change looks good but this is still failing on arm.
> > > > > >
> > > > > > ```
> > > > > > FAIL: elf/tst-gnu2-tls2
> > > > > > original exit status 1
> > > > > > open tst-gnu2-tls2mod0.so
> > > > > > open tst-gnu2-tls2mod1.so
> > > > > > open tst-gnu2-tls2mod2.so
> > > > > > close tst-gnu2-tls2mod0.so
> > > > > > close tst-gnu2-tls2mod1.so
> > > > > > open tst-gnu2-tls2mod0.so
> > > > > > open tst-gnu2-tls2mod1.so
> > > > > > Didn't expect signal from child: got `Segmentation fault'
> > > > > > ```
> > > > > >
> > > > > > HJ can you add some more logging to its clear exactly where
> > > > > > the fault is? (looks to be malloc or xdlsym).
> > > > >
> > > > > The new test may fail on targets which don't preserve all
> > > > > caller-saved registers in _dl_tlsdesc_dynamic.
> > > > >
> > > > > > Are there any other arch this is failing on? I.e is this an arm
> > > > > > bug or buggy test?
> > > > > >
> > > > >
> > > > > It is a bug on arm:
> > > > >
> > > > > https://github.com/zatrazz/glibc/commits/azanella/tls-descriptor-fixes-arm/
> > > >
> > > > Is anyone working on a fix for arm?
> > >
> > > There is a patch for arm in the URL above:
> > >
> > > https://github.com/zatrazz/glibc/commit/acdac4ff394e82ddf348c0eb03a8235ac0f67f7c
> > >
> >
> > Can you re-submit the patch to make the CI happy?
>
> That is Adhemerval's patch.  I prefer letting him decide what
> to do.  My patch doesn't change any target files.  I can make
> the new testcase x86 specific.  But I don't believe that we should
> make CI happy in this particular case.

Okay
>
> --
> H.J.
Noah Goldstein Feb. 24, 2024, 7 p.m. UTC | #8
On Fri, Feb 16, 2024 at 9:17 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> Compiler generates the following instruction sequence for GNU2 dynamic
> TLS access:
>
>         leaq    tls_var@TLSDESC(%rip), %rax
>         call    *tls_var@TLSCALL(%rax)
>
> or
>
>         leal    tls_var@TLSDESC(%ebx), %eax
>         call    *tls_var@TLSCALL(%eax)
>
> CALL instruction is transparent to compiler which assumes all registers,
> except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
> _dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
> path.  __tls_get_addr is a normal function which doesn't preserve any
> caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
> caller-saved registers, but didn't preserve any other caller-saved
> registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
> XSAVE and XSAVEC to save and restore all caller-saved registers.  This
> fixes BZ #31372.
>
> Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
> to optimize elf_machine_runtime_setup.
> ---
>  elf/Makefile                                 |  14 ++
>  elf/tst-gnu2-tls2.c                          | 120 ++++++++++++
>  elf/tst-gnu2-tls2.h                          |  36 ++++
>  elf/tst-gnu2-tls2mod0.c                      |  31 +++
>  elf/tst-gnu2-tls2mod1.c                      |  31 +++
>  elf/tst-gnu2-tls2mod2.c                      |  31 +++
>  sysdeps/i386/dl-machine.h                    |   2 +-
>  sysdeps/i386/dl-tlsdesc-dynamic.h            | 190 +++++++++++++++++++
>  sysdeps/i386/dl-tlsdesc.S                    | 115 +++++------
>  sysdeps/x86/Makefile                         |   7 +-
>  sysdeps/x86/cpu-features.c                   |  56 +++++-
>  sysdeps/x86/dl-procinfo.c                    |  16 ++
>  sysdeps/{x86_64 => x86}/features-offsets.sym |   2 +
>  sysdeps/x86/sysdep.h                         |   6 +
>  sysdeps/x86/tst-gnu2-tls2.c                  |  20 ++
>  sysdeps/x86_64/Makefile                      |   2 +-
>  sysdeps/x86_64/dl-machine.h                  |  19 +-
>  sysdeps/x86_64/dl-procinfo.c                 |  16 ++
>  sysdeps/x86_64/dl-tlsdesc-dynamic.h          | 166 ++++++++++++++++
>  sysdeps/x86_64/dl-tlsdesc.S                  | 108 ++++-------
>  sysdeps/x86_64/dl-trampoline-save.h          |  34 ++++
>  sysdeps/x86_64/dl-trampoline-state.h         |  51 +++++
>  sysdeps/x86_64/dl-trampoline.S               |  20 +-
>  sysdeps/x86_64/dl-trampoline.h               |  34 +---
>  24 files changed, 914 insertions(+), 213 deletions(-)
>  create mode 100644 elf/tst-gnu2-tls2.c
>  create mode 100644 elf/tst-gnu2-tls2.h
>  create mode 100644 elf/tst-gnu2-tls2mod0.c
>  create mode 100644 elf/tst-gnu2-tls2mod1.c
>  create mode 100644 elf/tst-gnu2-tls2mod2.c
>  create mode 100644 sysdeps/i386/dl-tlsdesc-dynamic.h
>  rename sysdeps/{x86_64 => x86}/features-offsets.sym (89%)
>  create mode 100644 sysdeps/x86/tst-gnu2-tls2.c
>  create mode 100644 sysdeps/x86_64/dl-tlsdesc-dynamic.h
>  create mode 100644 sysdeps/x86_64/dl-trampoline-save.h
>  create mode 100644 sysdeps/x86_64/dl-trampoline-state.h
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 5d78b659ce..030db4d207 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -424,6 +424,7 @@ tests += \
>    tst-glibc-hwcaps-prepend \
>    tst-global1 \
>    tst-global2 \
> +  tst-gnu2-tls2 \
>    tst-initfinilazyfail \
>    tst-initorder \
>    tst-initorder2 \
> @@ -846,6 +847,9 @@ modules-names += \
>    tst-filterobj-flt \
>    tst-finilazyfailmod \
>    tst-globalmod2 \
> +  tst-gnu2-tls2mod0 \
> +  tst-gnu2-tls2mod1 \
> +  tst-gnu2-tls2mod2 \
>    tst-initlazyfailmod \
>    tst-initorder2a \
>    tst-initorder2b \
> @@ -3044,8 +3048,18 @@ $(objpfx)tst-tlsgap.out: \
>    $(objpfx)tst-tlsgap-mod0.so \
>    $(objpfx)tst-tlsgap-mod1.so \
>    $(objpfx)tst-tlsgap-mod2.so
> +
> +$(objpfx)tst-gnu2-tls2: $(shared-thread-library)
> +$(objpfx)tst-gnu2-tls2.out: \
> +  $(objpfx)tst-gnu2-tls2mod0.so \
> +  $(objpfx)tst-gnu2-tls2mod1.so \
> +  $(objpfx)tst-gnu2-tls2mod2.so
> +
>  ifeq (yes,$(have-mtls-dialect-gnu2))
>  CFLAGS-tst-tlsgap-mod0.c += -mtls-dialect=gnu2
>  CFLAGS-tst-tlsgap-mod1.c += -mtls-dialect=gnu2
>  CFLAGS-tst-tlsgap-mod2.c += -mtls-dialect=gnu2
> +CFLAGS-tst-gnu2-tls2mod0.c += -mtls-dialect=gnu2
> +CFLAGS-tst-gnu2-tls2mod1.c += -mtls-dialect=gnu2
> +CFLAGS-tst-gnu2-tls2mod2.c += -mtls-dialect=gnu2
>  endif
> diff --git a/elf/tst-gnu2-tls2.c b/elf/tst-gnu2-tls2.c
> new file mode 100644
> index 0000000000..8039ba614d
> --- /dev/null
> +++ b/elf/tst-gnu2-tls2.c
> @@ -0,0 +1,120 @@
> +/* Test TLSDESC relocation.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <dlfcn.h>
> +#include <pthread.h>
> +#include <support/xdlfcn.h>
> +#include <support/xthread.h>
> +#include <support/check.h>
> +#include <support/test-driver.h>
> +#include "tst-gnu2-tls2.h"
> +
> +#ifndef IS_SUPPORTED
> +# define IS_SUPPORTED() true
> +#endif
> +
> +/* An architecture can define it to clobber caller-saved registers in
> +   malloc below to verify that the implicit TLSDESC call won't change
> +   caller-saved registers.  */
> +#ifndef PREPARE_MALLOC
> +# define PREPARE_MALLOC()
> +#endif
> +
> +extern void * __libc_malloc (size_t);
> +
> +size_t malloc_counter = 0;
> +
> +void *
> +malloc (size_t n)
> +{
> +  PREPARE_MALLOC ();
> +  malloc_counter++;
> +  return __libc_malloc (n);
> +}
> +
> +static void *mod[3];
> +#define MOD(i) "tst-gnu2-tls2mod" #i ".so"
> +static const char *modname[3] = { MOD(0), MOD(1), MOD(2) };
> +#undef MOD
> +
> +static void
> +open_mod (int i)
> +{
> +  mod[i] = xdlopen (modname[i], RTLD_LAZY);
> +  printf ("open %s\n", modname[i]);
> +}
> +
> +static void
> +close_mod (int i)
> +{
> +  xdlclose (mod[i]);
> +  mod[i] = NULL;
> +  printf ("close %s\n", modname[i]);
> +}
> +
> +static void
> +access_mod (int i, const char *sym)
> +{
> +  struct tls var = { -1, -1, -1, -1 };
> +  struct tls *(*f) (struct tls *) = xdlsym (mod[i], sym);
> +  /* Check that our malloc is called.  */
> +  malloc_counter = 0;
> +  struct tls *p = f (&var);
> +  TEST_VERIFY (malloc_counter != 0);
> +  printf ("access %s: %s() = %p\n", modname[i], sym, p);
> +  TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
> +  ++(p->a);
> +}
> +
> +static void *
> +start (void *arg)
> +{
> +  /* The DTV generation is at the last dlopen of mod0 and the
> +     entry for mod1 is NULL.  */
> +
> +  open_mod (1); /* Reuse modid of mod1. Uses dynamic TLS.  */
> +
> +  /* Force the slow path in GNU2 TLS descriptor call.  */
> +  access_mod (1, "apply_tls");
> +
> +  return arg;
> +}
> +
> +static int
> +do_test (void)
> +{
> +  if (!IS_SUPPORTED ())
> +    return EXIT_UNSUPPORTED;
> +
> +  open_mod (0);
> +  open_mod (1);
> +  open_mod (2);
> +  close_mod (0);
> +  close_mod (1); /* Create modid gap at mod1.  */
> +  open_mod (0); /* Reuse modid of mod0, bump generation count.  */
> +
> +  /* Create a thread where DTV of mod1 is NULL.  */
> +  pthread_t t = xpthread_create (NULL, start, NULL);
> +  xpthread_join (t);
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> diff --git a/elf/tst-gnu2-tls2.h b/elf/tst-gnu2-tls2.h
> new file mode 100644
> index 0000000000..77964a57a3
> --- /dev/null
> +++ b/elf/tst-gnu2-tls2.h
> @@ -0,0 +1,36 @@
> +/* Test TLSDESC relocation.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <stdint.h>
> +
> +struct tls
> +{
> +  int64_t a, b, c, d;
> +};
> +
> +extern struct tls *apply_tls (struct tls *);
> +
> +/* An architecture can define them to verify that clobber caller-saved
> +   registers aren't changed by the implicit TLSDESC call.  */
> +#ifndef BEFORE_TLSDESC_CALL
> +# define BEFORE_TLSDESC_CALL()
> +#endif
> +
> +#ifndef AFTER_TLSDESC_CALL
> +# define AFTER_TLSDESC_CALL()
> +#endif
> diff --git a/elf/tst-gnu2-tls2mod0.c b/elf/tst-gnu2-tls2mod0.c
> new file mode 100644
> index 0000000000..20f177244d
> --- /dev/null
> +++ b/elf/tst-gnu2-tls2mod0.c
> @@ -0,0 +1,31 @@
> +/* DSO used by tst-gnu2-tls2.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include "tst-gnu2-tls2.h"
> +
> +__thread struct tls tls_var0 __attribute__ ((visibility ("hidden")));
> +
> +struct tls *
> +apply_tls (struct tls *p)
> +{
> +  tls_var0 = *p;
> +  BEFORE_TLSDESC_CALL ();
> +  struct tls *ret = &tls_var0;
> +  AFTER_TLSDESC_CALL ();
> +  return ret;
> +}
> diff --git a/elf/tst-gnu2-tls2mod1.c b/elf/tst-gnu2-tls2mod1.c
> new file mode 100644
> index 0000000000..86a6ee48f7
> --- /dev/null
> +++ b/elf/tst-gnu2-tls2mod1.c
> @@ -0,0 +1,31 @@
> +/* DSO used by tst-gnu2-tls2.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include "tst-gnu2-tls2.h"
> +
> +__thread struct tls tls_var1[100] __attribute__ ((visibility ("hidden")));
> +
> +struct tls *
> +apply_tls (struct tls *p)
> +{
> +  tls_var1[1] = *p;
> +  BEFORE_TLSDESC_CALL ();
> +  struct tls *ret = &tls_var1[1];
> +  AFTER_TLSDESC_CALL ();
> +  return ret;
> +}
> diff --git a/elf/tst-gnu2-tls2mod2.c b/elf/tst-gnu2-tls2mod2.c
> new file mode 100644
> index 0000000000..dede07599b
> --- /dev/null
> +++ b/elf/tst-gnu2-tls2mod2.c
> @@ -0,0 +1,31 @@
> +/* DSO used by tst-gnu2-tls2.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include "tst-gnu2-tls2.h"
> +
> +__thread struct tls tls_var2 __attribute__ ((visibility ("hidden")));
> +
> +struct tls *
> +apply_tls (struct tls *p)
> +{
> +  tls_var2 = *p;
> +  BEFORE_TLSDESC_CALL ();
> +  struct tls *ret = &tls_var2;
> +  AFTER_TLSDESC_CALL ();
> +  return ret;
> +}
> diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
> index fc1ef96587..50d74fe6e9 100644
> --- a/sysdeps/i386/dl-machine.h
> +++ b/sysdeps/i386/dl-machine.h
> @@ -347,7 +347,7 @@ and creates an unsatisfiable circular dependency.\n",
>                   {
>                     td->arg = _dl_make_tlsdesc_dynamic
>                       (sym_map, sym->st_value + (ElfW(Word))td->arg);
> -                   td->entry = _dl_tlsdesc_dynamic;
> +                   td->entry = GLRO(dl_x86_tlsdesc_dynamic);
>                   }
>                 else
>  #  endif
> diff --git a/sysdeps/i386/dl-tlsdesc-dynamic.h b/sysdeps/i386/dl-tlsdesc-dynamic.h
> new file mode 100644
> index 0000000000..3627028577
> --- /dev/null
> +++ b/sysdeps/i386/dl-tlsdesc-dynamic.h
> @@ -0,0 +1,190 @@
> +/* Thread-local storage handling in the ELF dynamic linker.  i386 version.
> +   Copyright (C) 2004-2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#undef REGISTER_SAVE_AREA
> +
> +#if !defined USE_FNSAVE && (STATE_SAVE_ALIGNMENT % 16) != 0
> +# error STATE_SAVE_ALIGNMENT must be multiple of 16
> +#endif
> +
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +# ifdef USE_FNSAVE
> +#  error USE_FNSAVE shouldn't be defined
> +# endif
> +# ifdef USE_FXSAVE
> +/* Use fxsave to save all registers.  */
> +#  define REGISTER_SAVE_AREA   512
> +# endif
> +#else
> +# ifdef USE_FNSAVE
> +/* Use fnsave to save x87 FPU stack registers.  */
> +#  define REGISTER_SAVE_AREA   108
> +# else
> +#  ifndef USE_FXSAVE
> +#   error USE_FXSAVE must be defined
> +#  endif
> +/* Use fxsave to save all registers.  Add 12 bytes to align the stack
> +   to 16 bytes.  */
> +#  define REGISTER_SAVE_AREA   (512 + 12)
> +# endif
> +#endif
> +
> +       .hidden _dl_tlsdesc_dynamic
> +       .global _dl_tlsdesc_dynamic
> +       .type   _dl_tlsdesc_dynamic,@function
> +
> +     /* This function is used for symbols that need dynamic TLS.
> +
> +       %eax points to the TLS descriptor, such that 0(%eax) points to
> +       _dl_tlsdesc_dynamic itself, and 4(%eax) points to a struct
> +       tlsdesc_dynamic_arg object.  It must return in %eax the offset
> +       between the thread pointer and the object denoted by the
> +       argument, without clobbering any registers.
> +
> +       The assembly code that follows is a rendition of the following
> +       C code, hand-optimized a little bit.
> +
> +ptrdiff_t
> +__attribute__ ((__regparm__ (1)))
> +_dl_tlsdesc_dynamic (struct tlsdesc *tdp)
> +{
> +  struct tlsdesc_dynamic_arg *td = tdp->arg;
> +  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> +  if (__builtin_expect (td->gen_count <= dtv[0].counter
> +                       && (dtv[td->tlsinfo.ti_module].pointer.val
> +                           != TLS_DTV_UNALLOCATED),
> +                       1))
> +    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> +      - __thread_pointer;
> +
> +  return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
> +}
> +*/
> +       cfi_startproc
> +       .align 16
> +_dl_tlsdesc_dynamic:
> +       /* Like all TLS resolvers, preserve call-clobbered registers.
> +          We need two scratch regs anyway.  */
> +       subl    $32, %esp
> +       cfi_adjust_cfa_offset (32)
> +       movl    %ecx, 20(%esp)
> +       movl    %edx, 24(%esp)
> +       movl    TLSDESC_ARG(%eax), %eax
> +       movl    %gs:DTV_OFFSET, %edx
> +       movl    TLSDESC_GEN_COUNT(%eax), %ecx
> +       cmpl    (%edx), %ecx
> +       ja      2f
> +       movl    TLSDESC_MODID(%eax), %ecx
> +       movl    (%edx,%ecx,8), %edx
> +       cmpl    $-1, %edx
> +       je      2f
> +       movl    TLSDESC_MODOFF(%eax), %eax
> +       addl    %edx, %eax
> +1:
> +       movl    20(%esp), %ecx
> +       subl    %gs:0, %eax
> +       movl    24(%esp), %edx
> +       addl    $32, %esp
> +       cfi_adjust_cfa_offset (-32)
> +       ret
> +       .p2align 4,,7
> +2:
> +       cfi_adjust_cfa_offset (32)
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       movl    %ebx, -28(%esp)
> +       movl    %esp, %ebx
> +       cfi_def_cfa_register(%ebx)
> +       and     $-STATE_SAVE_ALIGNMENT, %esp
> +#endif
> +#ifdef REGISTER_SAVE_AREA
> +       subl    $REGISTER_SAVE_AREA, %esp
> +# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
> +# endif
> +#else
> +# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
> +#  error DL_RUNTIME_RESOLVE_REALIGN_STACK must be true
> +# endif
> +       /* Allocate stack space of the required size to save the state.  */
> +       LOAD_PIC_REG (cx)
> +       subl    RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_SIZE_OFFSET+_rtld_local_ro@GOTOFF(%ecx), %esp
> +#endif
> +#ifdef USE_FNSAVE
> +       fnsave  (%esp)
> +#elif defined USE_FXSAVE
> +       fxsave  (%esp)
> +#else
> +       /* Save the argument for ___tls_get_addr in EAX.  */
> +       movl    %eax, %ecx
> +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> +       xorl    %edx, %edx
> +       /* Clear the XSAVE Header.  */
> +# ifdef USE_XSAVE
> +       movl    %edx, (512)(%esp)
> +       movl    %edx, (512 + 4 * 1)(%esp)
> +       movl    %edx, (512 + 4 * 2)(%esp)
> +       movl    %edx, (512 + 4 * 3)(%esp)
> +# endif
> +       movl    %edx, (512 + 4 * 4)(%esp)
> +       movl    %edx, (512 + 4 * 5)(%esp)
> +       movl    %edx, (512 + 4 * 6)(%esp)
> +       movl    %edx, (512 + 4 * 7)(%esp)
> +       movl    %edx, (512 + 4 * 8)(%esp)
> +       movl    %edx, (512 + 4 * 9)(%esp)
> +       movl    %edx, (512 + 4 * 10)(%esp)
> +       movl    %edx, (512 + 4 * 11)(%esp)
> +       movl    %edx, (512 + 4 * 12)(%esp)
> +       movl    %edx, (512 + 4 * 13)(%esp)
> +       movl    %edx, (512 + 4 * 14)(%esp)
> +       movl    %edx, (512 + 4 * 15)(%esp)
> +# ifdef USE_XSAVE
> +       xsave   (%esp)
> +# else
> +       xsavec  (%esp)
> +# endif
> +       /* Restore the argument for ___tls_get_addr in EAX.  */
> +       movl    %ecx, %eax
> +#endif
> +       call    HIDDEN_JUMPTARGET (___tls_get_addr)
> +       /* Get register content back.  */
> +#ifdef USE_FNSAVE
> +       frstor  (%esp)
> +#elif defined USE_FXSAVE
> +       fxrstor (%esp)
> +#else
> +       /* Save and retore ___tls_get_addr return value stored in EAX.  */
> +       movl    %eax, %ecx
> +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> +       xorl    %edx, %edx
> +       xrstor  (%esp)
> +       movl    %ecx, %eax
> +#endif
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       mov     %ebx, %esp
> +       cfi_def_cfa_register(%esp)
> +       movl    -28(%esp), %ebx
> +       cfi_restore(%ebx)
> +#else
> +       addl    $REGISTER_SAVE_AREA, %esp
> +       cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
> +#endif
> +       jmp     1b
> +       cfi_endproc
> +       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> +
> +#undef STATE_SAVE_ALIGNMENT
> diff --git a/sysdeps/i386/dl-tlsdesc.S b/sysdeps/i386/dl-tlsdesc.S
> index 90d93caa0c..f002feee56 100644
> --- a/sysdeps/i386/dl-tlsdesc.S
> +++ b/sysdeps/i386/dl-tlsdesc.S
> @@ -18,8 +18,27 @@
>
>  #include <sysdep.h>
>  #include <tls.h>
> +#include <cpu-features-offsets.h>
> +#include <features-offsets.h>
>  #include "tlsdesc.h"
>
> +#ifndef DL_STACK_ALIGNMENT
> +/* Due to GCC bug:
> +
> +   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> +
> +   __tls_get_addr may be called with 4-byte stack alignment.  Although
> +   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
> +   that stack will be always aligned at 16 bytes.  */
> +# define DL_STACK_ALIGNMENT 4
> +#endif
> +
> +/* True if _dl_tlsdesc_dynamic should align stack for STATE_SAVE or align
> +   stack to MINIMUM_ALIGNMENT bytes before calling ___tls_get_addr.  */
> +#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> +  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> +   || MINIMUM_ALIGNMENT > DL_STACK_ALIGNMENT)
> +
>         .text
>
>       /* This function is used to compute the TP offset for symbols in
> @@ -65,69 +84,35 @@ _dl_tlsdesc_undefweak:
>         .size   _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
>
>  #ifdef SHARED
> -       .hidden _dl_tlsdesc_dynamic
> -       .global _dl_tlsdesc_dynamic
> -       .type   _dl_tlsdesc_dynamic,@function
> -
> -     /* This function is used for symbols that need dynamic TLS.
> -
> -       %eax points to the TLS descriptor, such that 0(%eax) points to
> -       _dl_tlsdesc_dynamic itself, and 4(%eax) points to a struct
> -       tlsdesc_dynamic_arg object.  It must return in %eax the offset
> -       between the thread pointer and the object denoted by the
> -       argument, without clobbering any registers.
> -
> -       The assembly code that follows is a rendition of the following
> -       C code, hand-optimized a little bit.
> -
> -ptrdiff_t
> -__attribute__ ((__regparm__ (1)))
> -_dl_tlsdesc_dynamic (struct tlsdesc *tdp)
> -{
> -  struct tlsdesc_dynamic_arg *td = tdp->arg;
> -  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> -  if (__builtin_expect (td->gen_count <= dtv[0].counter
> -                       && (dtv[td->tlsinfo.ti_module].pointer.val
> -                           != TLS_DTV_UNALLOCATED),
> -                       1))
> -    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> -      - __thread_pointer;
> -
> -  return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
> -}
> -*/
> -       cfi_startproc
> -       .align 16
> -_dl_tlsdesc_dynamic:
> -       /* Like all TLS resolvers, preserve call-clobbered registers.
> -          We need two scratch regs anyway.  */
> -       subl    $28, %esp
> -       cfi_adjust_cfa_offset (28)
> -       movl    %ecx, 20(%esp)
> -       movl    %edx, 24(%esp)
> -       movl    TLSDESC_ARG(%eax), %eax
> -       movl    %gs:DTV_OFFSET, %edx
> -       movl    TLSDESC_GEN_COUNT(%eax), %ecx
> -       cmpl    (%edx), %ecx
> -       ja      .Lslow
> -       movl    TLSDESC_MODID(%eax), %ecx
> -       movl    (%edx,%ecx,8), %edx
> -       cmpl    $-1, %edx
> -       je      .Lslow
> -       movl    TLSDESC_MODOFF(%eax), %eax
> -       addl    %edx, %eax
> -.Lret:
> -       movl    20(%esp), %ecx
> -       subl    %gs:0, %eax
> -       movl    24(%esp), %edx
> -       addl    $28, %esp
> -       cfi_adjust_cfa_offset (-28)
> -       ret
> -       .p2align 4,,7
> -.Lslow:
> -       cfi_adjust_cfa_offset (28)
> -       call    HIDDEN_JUMPTARGET (___tls_get_addr)
> -       jmp     .Lret
> -       cfi_endproc
> -       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> +# define USE_FNSAVE
> +# define MINIMUM_ALIGNMENT     4
> +# define STATE_SAVE_ALIGNMENT  4
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_fnsave
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef MINIMUM_ALIGNMENT
> +# undef USE_FNSAVE
> +
> +# define MINIMUM_ALIGNMENT     16
> +
> +# define USE_FXSAVE
> +# define STATE_SAVE_ALIGNMENT  16
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_fxsave
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_FXSAVE
> +
> +# define USE_XSAVE
> +# define STATE_SAVE_ALIGNMENT  64
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsave
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_XSAVE
> +
> +# define USE_XSAVEC
> +# define STATE_SAVE_ALIGNMENT  64
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsavec
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_XSAVEC
>  #endif /* SHARED */
> diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
> index 73b29cc78c..5311b594af 100644
> --- a/sysdeps/x86/Makefile
> +++ b/sysdeps/x86/Makefile
> @@ -1,5 +1,5 @@
>  ifeq ($(subdir),csu)
> -gen-as-const-headers += cpu-features-offsets.sym
> +gen-as-const-headers += cpu-features-offsets.sym features-offsets.sym
>  endif
>
>  ifeq ($(subdir),elf)
> @@ -86,6 +86,11 @@ endif
>  tst-ifunc-isa-2-ENV = GLIBC_TUNABLES=glibc.cpu.hwcaps=-SSE4_2,-AVX,-AVX2,-AVX512F
>  tst-ifunc-isa-2-static-ENV = $(tst-ifunc-isa-2-ENV)
>  tst-hwcap-tunables-ARGS = -- $(host-test-program-cmd)
> +
> +CFLAGS-tst-gnu2-tls2.c += -msse
> +CFLAGS-tst-gnu2-tls2mod0.c += -msse2 -mtune=haswell
> +CFLAGS-tst-gnu2-tls2mod1.c += -msse2 -mtune=haswell
> +CFLAGS-tst-gnu2-tls2mod2.c += -msse2 -mtune=haswell
>  endif
>
>  ifeq ($(subdir),math)
> diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> index 25e6622a79..835113b42f 100644
> --- a/sysdeps/x86/cpu-features.c
> +++ b/sysdeps/x86/cpu-features.c
> @@ -27,8 +27,13 @@
>  extern void TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *)
>    attribute_hidden;
>
> -#if defined SHARED && defined __x86_64__
> -# include <dl-plt-rewrite.h>
> +#if defined SHARED
> +extern void _dl_tlsdesc_dynamic_fxsave (void) attribute_hidden;
> +extern void _dl_tlsdesc_dynamic_xsave (void) attribute_hidden;
> +extern void _dl_tlsdesc_dynamic_xsavec (void) attribute_hidden;
> +
> +# ifdef __x86_64__
> +#  include <dl-plt-rewrite.h>
>
>  static void
>  TUNABLE_CALLBACK (set_plt_rewrite) (tunable_val_t *valp)
> @@ -47,6 +52,15 @@ TUNABLE_CALLBACK (set_plt_rewrite) (tunable_val_t *valp)
>                  : plt_rewrite_jmp);
>      }
>  }
> +# else
> +extern void _dl_tlsdesc_dynamic_fnsave (void) attribute_hidden;
> +# endif
> +#endif
> +
> +#ifdef __x86_64__
> +extern void _dl_runtime_resolve_fxsave (void) attribute_hidden;
> +extern void _dl_runtime_resolve_xsave (void) attribute_hidden;
> +extern void _dl_runtime_resolve_xsavec (void) attribute_hidden;
>  #endif
>
>  #ifdef __LP64__
> @@ -1130,6 +1144,44 @@ no_cpuid:
>                TUNABLE_CALLBACK (set_x86_shstk));
>  #endif
>
> +  if (GLRO(dl_x86_cpu_features).xsave_state_size != 0)
> +    {
> +      if (CPU_FEATURE_USABLE_P (cpu_features, XSAVEC))
> +       {
> +#ifdef __x86_64__
> +         GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_xsavec;
> +#endif
> +#ifdef SHARED
> +         GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_xsavec;
> +#endif
> +       }
> +      else
> +       {
> +#ifdef __x86_64__
> +         GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_xsave;
> +#endif
> +#ifdef SHARED
> +         GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_xsave;
> +#endif
> +       }
> +    }
> +  else
> +    {
> +#ifdef __x86_64__
> +      GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_fxsave;
> +# ifdef SHARED
> +      GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fxsave;
> +# endif
> +#else
> +# ifdef SHARED
> +      if (CPU_FEATURE_USABLE_P (cpu_features, FXSR))
> +       GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fxsave;
> +      else
> +       GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fnsave;
> +# endif
> +#endif
> +    }
> +
>  #ifdef SHARED
>  # ifdef __x86_64__
>    TUNABLE_GET (plt_rewrite, tunable_val_t *,
> diff --git a/sysdeps/x86/dl-procinfo.c b/sysdeps/x86/dl-procinfo.c
> index ee957b4d70..5920d4b320 100644
> --- a/sysdeps/x86/dl-procinfo.c
> +++ b/sysdeps/x86/dl-procinfo.c
> @@ -86,3 +86,19 @@ PROCINFO_CLASS const char _dl_x86_platforms[4][9]
>  #else
>  ,
>  #endif
> +
> +#if defined SHARED && !IS_IN (ldconfig)
> +# if !defined PROCINFO_DECL
> +  ._dl_x86_tlsdesc_dynamic
> +# else
> +PROCINFO_CLASS void * _dl_x86_tlsdesc_dynamic
> +# endif
> +# ifndef PROCINFO_DECL
> += NULL
> +# endif
> +# ifdef PROCINFO_DECL
> +;
> +# else
> +,
> +# endif
> +#endif
> diff --git a/sysdeps/x86_64/features-offsets.sym b/sysdeps/x86/features-offsets.sym
> similarity index 89%
> rename from sysdeps/x86_64/features-offsets.sym
> rename to sysdeps/x86/features-offsets.sym
> index 9e4be3393a..77e990c705 100644
> --- a/sysdeps/x86_64/features-offsets.sym
> +++ b/sysdeps/x86/features-offsets.sym
> @@ -3,4 +3,6 @@
>  #include <ldsodefs.h>
>
>  RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET offsetof (struct rtld_global_ro, _dl_x86_cpu_features)
> +#ifdef __x86_64__
>  RTLD_GLOBAL_DL_X86_FEATURE_1_OFFSET offsetof (struct rtld_global, _dl_x86_feature_1)
> +#endif
> diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
> index 837fd28734..485cad9c02 100644
> --- a/sysdeps/x86/sysdep.h
> +++ b/sysdeps/x86/sysdep.h
> @@ -70,6 +70,12 @@
>     | (1 << X86_XSTATE_ZMM_H_ID))
>  #endif
>
> +/* States which should be saved for TLSDESC_CALL and TLS_DESC_CALL.
> +   Compiler assumes that all registers, including x87 FPU stack registers,
> +   are unchanged after CALL, except for EFLAGS and RAX/EAX.  */
> +#define TLSDESC_CALL_STATE_SAVE_MASK   \
> +  (STATE_SAVE_MASK | (1 << X86_XSTATE_X87_ID))
> +
>  /* Constants for bits in __x86_string_control:  */
>
>  /* Avoid short distance REP MOVSB.  */
> diff --git a/sysdeps/x86/tst-gnu2-tls2.c b/sysdeps/x86/tst-gnu2-tls2.c
> new file mode 100644
> index 0000000000..de900a423b
> --- /dev/null
> +++ b/sysdeps/x86/tst-gnu2-tls2.c
> @@ -0,0 +1,20 @@
> +#ifndef __x86_64__
> +#include <sys/platform/x86.h>
> +
> +#define IS_SUPPORTED() CPU_FEATURE_ACTIVE (SSE2)
> +#endif
> +
> +/* Clear XMM0...XMM7  */
> +#define PREPARE_MALLOC()                               \
> +{                                                      \
> +  asm volatile ("xorps %%xmm0, %%xmm0" : : : "xmm0" ); \
> +  asm volatile ("xorps %%xmm1, %%xmm1" : : : "xmm1" ); \
> +  asm volatile ("xorps %%xmm2, %%xmm2" : : : "xmm2" ); \
> +  asm volatile ("xorps %%xmm3, %%xmm3" : : : "xmm3" ); \
> +  asm volatile ("xorps %%xmm4, %%xmm4" : : : "xmm4" ); \
> +  asm volatile ("xorps %%xmm5, %%xmm5" : : : "xmm5" ); \
> +  asm volatile ("xorps %%xmm6, %%xmm6" : : : "xmm6" ); \
> +  asm volatile ("xorps %%xmm7, %%xmm7" : : : "xmm7" ); \
> +}
> +
> +#include <elf/tst-gnu2-tls2.c>
> diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile
> index 145f25e7f6..9337e95093 100644
> --- a/sysdeps/x86_64/Makefile
> +++ b/sysdeps/x86_64/Makefile
> @@ -10,7 +10,7 @@ LDFLAGS-rtld += -Wl,-z,nomark-plt
>  endif
>
>  ifeq ($(subdir),csu)
> -gen-as-const-headers += features-offsets.sym link-defines.sym
> +gen-as-const-headers += link-defines.sym
>  endif
>
>  ifeq ($(subdir),gmon)
> diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
> index 6d605d0d32..ff5d45f7cb 100644
> --- a/sysdeps/x86_64/dl-machine.h
> +++ b/sysdeps/x86_64/dl-machine.h
> @@ -71,9 +71,6 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
>                            int lazy, int profile)
>  {
>    Elf64_Addr *got;
> -  extern void _dl_runtime_resolve_fxsave (ElfW(Word)) attribute_hidden;
> -  extern void _dl_runtime_resolve_xsave (ElfW(Word)) attribute_hidden;
> -  extern void _dl_runtime_resolve_xsavec (ElfW(Word)) attribute_hidden;
>    extern void _dl_runtime_profile_sse (ElfW(Word)) attribute_hidden;
>    extern void _dl_runtime_profile_avx (ElfW(Word)) attribute_hidden;
>    extern void _dl_runtime_profile_avx512 (ElfW(Word)) attribute_hidden;
> @@ -96,8 +93,6 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
>        /* Identify this shared object.  */
>        *(ElfW(Addr) *) (got + 1) = (ElfW(Addr)) l;
>
> -      const struct cpu_features* cpu_features = __get_cpu_features ();
> -
>  #ifdef SHARED
>        /* The got[2] entry contains the address of a function which gets
>          called to get the address of a so far unresolved function and
> @@ -107,6 +102,7 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
>          end in this function.  */
>        if (__glibc_unlikely (profile))
>         {
> +         const struct cpu_features* cpu_features = __get_cpu_features ();
>           if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512F))
>             *(ElfW(Addr) *) (got + 2) = (ElfW(Addr)) &_dl_runtime_profile_avx512;
>           else if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX))
> @@ -126,15 +122,8 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
>           /* This function will get called to fix up the GOT entry
>              indicated by the offset on the stack, and then jump to
>              the resolved address.  */
> -         if (MINIMUM_X86_ISA_LEVEL >= AVX_X86_ISA_LEVEL
> -             || GLRO(dl_x86_cpu_features).xsave_state_size != 0)
> -           *(ElfW(Addr) *) (got + 2)
> -             = (CPU_FEATURE_USABLE_P (cpu_features, XSAVEC)
> -                ? (ElfW(Addr)) &_dl_runtime_resolve_xsavec
> -                : (ElfW(Addr)) &_dl_runtime_resolve_xsave);
> -         else
> -           *(ElfW(Addr) *) (got + 2)
> -             = (ElfW(Addr)) &_dl_runtime_resolve_fxsave;
> +         *(ElfW(Addr) *) (got + 2)
> +           = (ElfW(Addr)) GLRO(dl_x86_64_runtime_resolve);
>         }
>      }
>
> @@ -383,7 +372,7 @@ and creates an unsatisfiable circular dependency.\n",
>                   {
>                     td->arg = _dl_make_tlsdesc_dynamic
>                       (sym_map, sym->st_value + reloc->r_addend);
> -                   td->entry = _dl_tlsdesc_dynamic;
> +                   td->entry = GLRO(dl_x86_tlsdesc_dynamic);
>                   }
>                 else
>  #  endif
> diff --git a/sysdeps/x86_64/dl-procinfo.c b/sysdeps/x86_64/dl-procinfo.c
> index 4d1d790fbb..06637a8154 100644
> --- a/sysdeps/x86_64/dl-procinfo.c
> +++ b/sysdeps/x86_64/dl-procinfo.c
> @@ -41,5 +41,21 @@
>
>  #include <sysdeps/x86/dl-procinfo.c>
>
> +#if !IS_IN (ldconfig)
> +# if !defined PROCINFO_DECL && defined SHARED
> +  ._dl_x86_64_runtime_resolve
> +# else
> +PROCINFO_CLASS void * _dl_x86_64_runtime_resolve
> +# endif
> +# ifndef PROCINFO_DECL
> += NULL
> +# endif
> +# if !defined SHARED || defined PROCINFO_DECL
> +;
> +# else
> +,
> +# endif
> +#endif
> +
>  #undef PROCINFO_DECL
>  #undef PROCINFO_CLASS
> diff --git a/sysdeps/x86_64/dl-tlsdesc-dynamic.h b/sysdeps/x86_64/dl-tlsdesc-dynamic.h
> new file mode 100644
> index 0000000000..0c2e8d5320
> --- /dev/null
> +++ b/sysdeps/x86_64/dl-tlsdesc-dynamic.h
> @@ -0,0 +1,166 @@
> +/* Thread-local storage handling in the ELF dynamic linker.  x86_64 version.
> +   Copyright (C) 2004-2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef SECTION
> +# define SECTION(p)    p
> +#endif
> +
> +#undef REGISTER_SAVE_AREA
> +#undef LOCAL_STORAGE_AREA
> +#undef BASE
> +
> +#include "dl-trampoline-state.h"
> +
> +       .section SECTION(.text),"ax",@progbits
> +
> +       .hidden _dl_tlsdesc_dynamic
> +       .global _dl_tlsdesc_dynamic
> +       .type   _dl_tlsdesc_dynamic,@function
> +
> +     /* %rax points to the TLS descriptor, such that 0(%rax) points to
> +       _dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct
> +       tlsdesc_dynamic_arg object.  It must return in %rax the offset
> +       between the thread pointer and the object denoted by the
> +       argument, without clobbering any registers.
> +
> +       The assembly code that follows is a rendition of the following
> +       C code, hand-optimized a little bit.
> +
> +ptrdiff_t
> +_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax"))
> +{
> +  struct tlsdesc_dynamic_arg *td = tdp->arg;
> +  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> +  if (__builtin_expect (td->gen_count <= dtv[0].counter
> +                       && (dtv[td->tlsinfo.ti_module].pointer.val
> +                           != TLS_DTV_UNALLOCATED),
> +                       1))
> +    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> +      - __thread_pointer;
> +
> +  return __tls_get_addr_internal (&td->tlsinfo) - __thread_pointer;
> +}
> +*/
> +       cfi_startproc
> +       .align 16
> +_dl_tlsdesc_dynamic:
> +       _CET_ENDBR
> +       /* Preserve call-clobbered registers that we modify.
> +          We need two scratch regs anyway.  */
> +       movq    %rsi, -16(%rsp)
> +       mov     %fs:DTV_OFFSET, %RSI_LP
> +       movq    %rdi, -8(%rsp)
> +       movq    TLSDESC_ARG(%rax), %rdi
> +       movq    (%rsi), %rax
> +       cmpq    %rax, TLSDESC_GEN_COUNT(%rdi)
> +       ja      2f
> +       movq    TLSDESC_MODID(%rdi), %rax
> +       salq    $4, %rax
> +       movq    (%rax,%rsi), %rax
> +       cmpq    $-1, %rax
> +       je      2f
> +       addq    TLSDESC_MODOFF(%rdi), %rax
> +1:
> +       movq    -16(%rsp), %rsi
> +       sub     %fs:0, %RAX_LP
> +       movq    -8(%rsp), %rdi
> +       ret
> +2:
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       movq    %rbx, -24(%rsp)
> +       mov     %RSP_LP, %RBX_LP
> +       cfi_def_cfa_register(%rbx)
> +       and     $-STATE_SAVE_ALIGNMENT, %RSP_LP
> +#endif
> +#ifdef REGISTER_SAVE_AREA
> +# if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       /* STATE_SAVE_OFFSET has space for 8 integer registers.  But we
> +          need space for RCX, RDX, RSI, RDI, R8, R9, R10 and R11, plus
> +          RBX above.  */
> +       sub     $(REGISTER_SAVE_AREA + STATE_SAVE_ALIGNMENT), %RSP_LP
> +# else
> +       sub     $REGISTER_SAVE_AREA, %RSP_LP
> +       cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
> +# endif
> +#else
> +       /* Allocate stack space of the required size to save the state.  */
> +       sub     _rtld_local_ro+RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_SIZE_OFFSET(%rip), %RSP_LP
> +#endif
> +       /* Besides rdi and rsi, saved above, save rcx, rdx, r8, r9,
> +          r10 and r11.  */
> +       movq    %rcx, REGISTER_SAVE_RCX(%rsp)
> +       movq    %rdx, REGISTER_SAVE_RDX(%rsp)
> +       movq    %r8, REGISTER_SAVE_R8(%rsp)
> +       movq    %r9, REGISTER_SAVE_R9(%rsp)
> +       movq    %r10, REGISTER_SAVE_R10(%rsp)
> +       movq    %r11, REGISTER_SAVE_R11(%rsp)
> +#ifdef USE_FXSAVE
> +       fxsave  STATE_SAVE_OFFSET(%rsp)
> +#else
> +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> +       xorl    %edx, %edx
> +       /* Clear the XSAVE Header.  */
> +# ifdef USE_XSAVE
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8)(%rsp)
> +# endif
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 2)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 3)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 4)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 5)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 6)(%rsp)
> +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 7)(%rsp)
> +# ifdef USE_XSAVE
> +       xsave   STATE_SAVE_OFFSET(%rsp)
> +# else
> +       xsavec  STATE_SAVE_OFFSET(%rsp)
> +# endif
> +#endif
> +       /* %rdi already points to the tlsinfo data structure.  */
> +       call    HIDDEN_JUMPTARGET (__tls_get_addr)
> +       # Get register content back.
> +#ifdef USE_FXSAVE
> +       fxrstor STATE_SAVE_OFFSET(%rsp)
> +#else
> +       /* Save and retore __tls_get_addr return value stored in RAX.  */
> +       mov     %RAX_LP, %RCX_LP
> +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> +       xorl    %edx, %edx
> +       xrstor  STATE_SAVE_OFFSET(%rsp)
> +       mov     %RCX_LP, %RAX_LP
> +#endif
> +       movq    REGISTER_SAVE_R11(%rsp), %r11
> +       movq    REGISTER_SAVE_R10(%rsp), %r10
> +       movq    REGISTER_SAVE_R9(%rsp), %r9
> +       movq    REGISTER_SAVE_R8(%rsp), %r8
> +       movq    REGISTER_SAVE_RDX(%rsp), %rdx
> +       movq    REGISTER_SAVE_RCX(%rsp), %rcx
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +       mov     %RBX_LP, %RSP_LP
> +       cfi_def_cfa_register(%rsp)
> +       movq    -24(%rsp), %rbx
> +       cfi_restore(%rbx)
> +#else
> +       add     $REGISTER_SAVE_AREA, %RSP_LP
> +       cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
> +#endif
> +       jmp     1b
> +       cfi_endproc
> +       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> +
> +#undef STATE_SAVE_ALIGNMENT
> diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S
> index f748af2ece..ea69f5223a 100644
> --- a/sysdeps/x86_64/dl-tlsdesc.S
> +++ b/sysdeps/x86_64/dl-tlsdesc.S
> @@ -18,7 +18,19 @@
>
>  #include <sysdep.h>
>  #include <tls.h>
> +#include <cpu-features-offsets.h>
> +#include <features-offsets.h>
>  #include "tlsdesc.h"
> +#include "dl-trampoline-save.h"
> +
> +/* Area on stack to save and restore registers used for parameter
> +   passing when calling _dl_tlsdesc_dynamic.  */
> +#define REGISTER_SAVE_RCX      0
> +#define REGISTER_SAVE_RDX      (REGISTER_SAVE_RCX + 8)
> +#define REGISTER_SAVE_R8       (REGISTER_SAVE_RDX + 8)
> +#define REGISTER_SAVE_R9       (REGISTER_SAVE_R8 + 8)
> +#define REGISTER_SAVE_R10      (REGISTER_SAVE_R9 + 8)
> +#define REGISTER_SAVE_R11      (REGISTER_SAVE_R10 + 8)
>
>         .text
>
> @@ -67,80 +79,24 @@ _dl_tlsdesc_undefweak:
>         .size   _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
>
>  #ifdef SHARED
> -       .hidden _dl_tlsdesc_dynamic
> -       .global _dl_tlsdesc_dynamic
> -       .type   _dl_tlsdesc_dynamic,@function
> -
> -     /* %rax points to the TLS descriptor, such that 0(%rax) points to
> -       _dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct
> -       tlsdesc_dynamic_arg object.  It must return in %rax the offset
> -       between the thread pointer and the object denoted by the
> -       argument, without clobbering any registers.
> -
> -       The assembly code that follows is a rendition of the following
> -       C code, hand-optimized a little bit.
> -
> -ptrdiff_t
> -_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax"))
> -{
> -  struct tlsdesc_dynamic_arg *td = tdp->arg;
> -  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> -  if (__builtin_expect (td->gen_count <= dtv[0].counter
> -                       && (dtv[td->tlsinfo.ti_module].pointer.val
> -                           != TLS_DTV_UNALLOCATED),
> -                       1))
> -    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> -      - __thread_pointer;
> -
> -  return __tls_get_addr_internal (&td->tlsinfo) - __thread_pointer;
> -}
> -*/
> -       cfi_startproc
> -       .align 16
> -_dl_tlsdesc_dynamic:
> -       _CET_ENDBR
> -       /* Preserve call-clobbered registers that we modify.
> -          We need two scratch regs anyway.  */
> -       movq    %rsi, -16(%rsp)
> -       mov     %fs:DTV_OFFSET, %RSI_LP
> -       movq    %rdi, -8(%rsp)
> -       movq    TLSDESC_ARG(%rax), %rdi
> -       movq    (%rsi), %rax
> -       cmpq    %rax, TLSDESC_GEN_COUNT(%rdi)
> -       ja      .Lslow
> -       movq    TLSDESC_MODID(%rdi), %rax
> -       salq    $4, %rax
> -       movq    (%rax,%rsi), %rax
> -       cmpq    $-1, %rax
> -       je      .Lslow
> -       addq    TLSDESC_MODOFF(%rdi), %rax
> -.Lret:
> -       movq    -16(%rsp), %rsi
> -       sub     %fs:0, %RAX_LP
> -       movq    -8(%rsp), %rdi
> -       ret
> -.Lslow:
> -       /* Besides rdi and rsi, saved above, save rdx, rcx, r8, r9,
> -          r10 and r11.  Also, align the stack, that's off by 8 bytes.  */
> -       subq    $72, %rsp
> -       cfi_adjust_cfa_offset (72)
> -       movq    %rdx, 8(%rsp)
> -       movq    %rcx, 16(%rsp)
> -       movq    %r8, 24(%rsp)
> -       movq    %r9, 32(%rsp)
> -       movq    %r10, 40(%rsp)
> -       movq    %r11, 48(%rsp)
> -       /* %rdi already points to the tlsinfo data structure.  */
> -       call    HIDDEN_JUMPTARGET (__tls_get_addr)
> -       movq    8(%rsp), %rdx
> -       movq    16(%rsp), %rcx
> -       movq    24(%rsp), %r8
> -       movq    32(%rsp), %r9
> -       movq    40(%rsp), %r10
> -       movq    48(%rsp), %r11
> -       addq    $72, %rsp
> -       cfi_adjust_cfa_offset (-72)
> -       jmp     .Lret
> -       cfi_endproc
> -       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> +# define USE_FXSAVE
> +# define STATE_SAVE_ALIGNMENT  16
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_fxsave
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_FXSAVE
> +
> +# define USE_XSAVE
> +# define STATE_SAVE_ALIGNMENT  64
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsave
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_XSAVE
> +
> +# define USE_XSAVEC
> +# define STATE_SAVE_ALIGNMENT  64
> +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsavec
> +# include "dl-tlsdesc-dynamic.h"
> +# undef _dl_tlsdesc_dynamic
> +# undef USE_XSAVEC
>  #endif /* SHARED */
> diff --git a/sysdeps/x86_64/dl-trampoline-save.h b/sysdeps/x86_64/dl-trampoline-save.h
> new file mode 100644
> index 0000000000..84eac4a8ac
> --- /dev/null
> +++ b/sysdeps/x86_64/dl-trampoline-save.h
> @@ -0,0 +1,34 @@
> +/* x86-64 PLT trampoline register save macros.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef DL_STACK_ALIGNMENT
> +/* Due to GCC bug:
> +
> +   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> +
> +   __tls_get_addr may be called with 8-byte stack alignment.  Although
> +   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
> +   that stack will be always aligned at 16 bytes.  */
> +# define DL_STACK_ALIGNMENT 8
> +#endif
> +
> +/* True if _dl_runtime_resolve should align stack for STATE_SAVE or align
> +   stack to 16 bytes before calling _dl_fixup.  */
> +#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> +  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> +   || 16 > DL_STACK_ALIGNMENT)
> diff --git a/sysdeps/x86_64/dl-trampoline-state.h b/sysdeps/x86_64/dl-trampoline-state.h
> new file mode 100644
> index 0000000000..575f120797
> --- /dev/null
> +++ b/sysdeps/x86_64/dl-trampoline-state.h
> @@ -0,0 +1,51 @@
> +/* x86-64 PLT dl-trampoline state macros.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#if (STATE_SAVE_ALIGNMENT % 16) != 0
> +# error STATE_SAVE_ALIGNMENT must be multiple of 16
> +#endif
> +
> +#if (STATE_SAVE_OFFSET % STATE_SAVE_ALIGNMENT) != 0
> +# error STATE_SAVE_OFFSET must be multiple of STATE_SAVE_ALIGNMENT
> +#endif
> +
> +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> +/* Local stack area before jumping to function address: RBX.  */
> +# define LOCAL_STORAGE_AREA    8
> +# define BASE                  rbx
> +# ifdef USE_FXSAVE
> +/* Use fxsave to save XMM registers.  */
> +#  define REGISTER_SAVE_AREA   (512 + STATE_SAVE_OFFSET)
> +#  if (REGISTER_SAVE_AREA % 16) != 0
> +#   error REGISTER_SAVE_AREA must be multiple of 16
> +#  endif
> +# endif
> +#else
> +# ifndef USE_FXSAVE
> +#  error USE_FXSAVE must be defined
> +# endif
> +/* Use fxsave to save XMM registers.  */
> +# define REGISTER_SAVE_AREA    (512 + STATE_SAVE_OFFSET + 8)
> +/* Local stack area before jumping to function address:  All saved
> +   registers.  */
> +# define LOCAL_STORAGE_AREA    REGISTER_SAVE_AREA
> +# define BASE                  rsp
> +# if (REGISTER_SAVE_AREA % 16) != 8
> +#  error REGISTER_SAVE_AREA must be odd multiple of 8
> +# endif
> +#endif
> diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S
> index b2e7e0f69b..87c5137837 100644
> --- a/sysdeps/x86_64/dl-trampoline.S
> +++ b/sysdeps/x86_64/dl-trampoline.S
> @@ -22,25 +22,7 @@
>  #include <features-offsets.h>
>  #include <link-defines.h>
>  #include <isa-level.h>
> -
> -#ifndef DL_STACK_ALIGNMENT
> -/* Due to GCC bug:
> -
> -   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> -
> -   __tls_get_addr may be called with 8-byte stack alignment.  Although
> -   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
> -   that stack will be always aligned at 16 bytes.  We use unaligned
> -   16-byte move to load and store SSE registers, which has no penalty
> -   on modern processors if stack is 16-byte aligned.  */
> -# define DL_STACK_ALIGNMENT 8
> -#endif
> -
> -/* True if _dl_runtime_resolve should align stack for STATE_SAVE or align
> -   stack to 16 bytes before calling _dl_fixup.  */
> -#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> -  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> -   || 16 > DL_STACK_ALIGNMENT)
> +#include "dl-trampoline-save.h"
>
>  /* Area on stack to save and restore registers used for parameter
>     passing when calling _dl_fixup.  */
> diff --git a/sysdeps/x86_64/dl-trampoline.h b/sysdeps/x86_64/dl-trampoline.h
> index f55c6ea040..d9ccfb40d4 100644
> --- a/sysdeps/x86_64/dl-trampoline.h
> +++ b/sysdeps/x86_64/dl-trampoline.h
> @@ -27,39 +27,7 @@
>  # undef LOCAL_STORAGE_AREA
>  # undef BASE
>
> -# if (STATE_SAVE_ALIGNMENT % 16) != 0
> -#  error STATE_SAVE_ALIGNMENT must be multiple of 16
> -# endif
> -
> -# if (STATE_SAVE_OFFSET % STATE_SAVE_ALIGNMENT) != 0
> -#  error STATE_SAVE_OFFSET must be multiple of STATE_SAVE_ALIGNMENT
> -# endif
> -
> -# if DL_RUNTIME_RESOLVE_REALIGN_STACK
> -/* Local stack area before jumping to function address: RBX.  */
> -#  define LOCAL_STORAGE_AREA   8
> -#  define BASE                 rbx
> -#  ifdef USE_FXSAVE
> -/* Use fxsave to save XMM registers.  */
> -#   define REGISTER_SAVE_AREA  (512 + STATE_SAVE_OFFSET)
> -#   if (REGISTER_SAVE_AREA % 16) != 0
> -#    error REGISTER_SAVE_AREA must be multiple of 16
> -#   endif
> -#  endif
> -# else
> -#  ifndef USE_FXSAVE
> -#   error USE_FXSAVE must be defined
> -#  endif
> -/* Use fxsave to save XMM registers.  */
> -#  define REGISTER_SAVE_AREA   (512 + STATE_SAVE_OFFSET + 8)
> -/* Local stack area before jumping to function address:  All saved
> -   registers.  */
> -#  define LOCAL_STORAGE_AREA   REGISTER_SAVE_AREA
> -#  define BASE                 rsp
> -#  if (REGISTER_SAVE_AREA % 16) != 8
> -#   error REGISTER_SAVE_AREA must be odd multiple of 8
> -#  endif
> -# endif
> +# include "dl-trampoline-state.h"
>
>         .globl _dl_runtime_resolve
>         .hidden _dl_runtime_resolve
> --
> 2.43.0
>

LGTM.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>

Please wait for adhemerval to give the clear as well.
H.J. Lu Feb. 24, 2024, 7:10 p.m. UTC | #9
On Sat, Feb 24, 2024 at 11:00 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Fri, Feb 16, 2024 at 9:17 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > Compiler generates the following instruction sequence for GNU2 dynamic
> > TLS access:
> >
> >         leaq    tls_var@TLSDESC(%rip), %rax
> >         call    *tls_var@TLSCALL(%rax)
> >
> > or
> >
> >         leal    tls_var@TLSDESC(%ebx), %eax
> >         call    *tls_var@TLSCALL(%eax)
> >
> > CALL instruction is transparent to compiler which assumes all registers,
> > except for EFLAGS and RAX/EAX, are unchanged after CALL.  When
> > _dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
> > path.  __tls_get_addr is a normal function which doesn't preserve any
> > caller-saved registers.  _dl_tlsdesc_dynamic saved and restored integer
> > caller-saved registers, but didn't preserve any other caller-saved
> > registers.  Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
> > XSAVE and XSAVEC to save and restore all caller-saved registers.  This
> > fixes BZ #31372.
> >
> > Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
> > to optimize elf_machine_runtime_setup.
> > ---
> >  elf/Makefile                                 |  14 ++
> >  elf/tst-gnu2-tls2.c                          | 120 ++++++++++++
> >  elf/tst-gnu2-tls2.h                          |  36 ++++
> >  elf/tst-gnu2-tls2mod0.c                      |  31 +++
> >  elf/tst-gnu2-tls2mod1.c                      |  31 +++
> >  elf/tst-gnu2-tls2mod2.c                      |  31 +++
> >  sysdeps/i386/dl-machine.h                    |   2 +-
> >  sysdeps/i386/dl-tlsdesc-dynamic.h            | 190 +++++++++++++++++++
> >  sysdeps/i386/dl-tlsdesc.S                    | 115 +++++------
> >  sysdeps/x86/Makefile                         |   7 +-
> >  sysdeps/x86/cpu-features.c                   |  56 +++++-
> >  sysdeps/x86/dl-procinfo.c                    |  16 ++
> >  sysdeps/{x86_64 => x86}/features-offsets.sym |   2 +
> >  sysdeps/x86/sysdep.h                         |   6 +
> >  sysdeps/x86/tst-gnu2-tls2.c                  |  20 ++
> >  sysdeps/x86_64/Makefile                      |   2 +-
> >  sysdeps/x86_64/dl-machine.h                  |  19 +-
> >  sysdeps/x86_64/dl-procinfo.c                 |  16 ++
> >  sysdeps/x86_64/dl-tlsdesc-dynamic.h          | 166 ++++++++++++++++
> >  sysdeps/x86_64/dl-tlsdesc.S                  | 108 ++++-------
> >  sysdeps/x86_64/dl-trampoline-save.h          |  34 ++++
> >  sysdeps/x86_64/dl-trampoline-state.h         |  51 +++++
> >  sysdeps/x86_64/dl-trampoline.S               |  20 +-
> >  sysdeps/x86_64/dl-trampoline.h               |  34 +---
> >  24 files changed, 914 insertions(+), 213 deletions(-)
> >  create mode 100644 elf/tst-gnu2-tls2.c
> >  create mode 100644 elf/tst-gnu2-tls2.h
> >  create mode 100644 elf/tst-gnu2-tls2mod0.c
> >  create mode 100644 elf/tst-gnu2-tls2mod1.c
> >  create mode 100644 elf/tst-gnu2-tls2mod2.c
> >  create mode 100644 sysdeps/i386/dl-tlsdesc-dynamic.h
> >  rename sysdeps/{x86_64 => x86}/features-offsets.sym (89%)
> >  create mode 100644 sysdeps/x86/tst-gnu2-tls2.c
> >  create mode 100644 sysdeps/x86_64/dl-tlsdesc-dynamic.h
> >  create mode 100644 sysdeps/x86_64/dl-trampoline-save.h
> >  create mode 100644 sysdeps/x86_64/dl-trampoline-state.h
> >
> > diff --git a/elf/Makefile b/elf/Makefile
> > index 5d78b659ce..030db4d207 100644
> > --- a/elf/Makefile
> > +++ b/elf/Makefile
> > @@ -424,6 +424,7 @@ tests += \
> >    tst-glibc-hwcaps-prepend \
> >    tst-global1 \
> >    tst-global2 \
> > +  tst-gnu2-tls2 \
> >    tst-initfinilazyfail \
> >    tst-initorder \
> >    tst-initorder2 \
> > @@ -846,6 +847,9 @@ modules-names += \
> >    tst-filterobj-flt \
> >    tst-finilazyfailmod \
> >    tst-globalmod2 \
> > +  tst-gnu2-tls2mod0 \
> > +  tst-gnu2-tls2mod1 \
> > +  tst-gnu2-tls2mod2 \
> >    tst-initlazyfailmod \
> >    tst-initorder2a \
> >    tst-initorder2b \
> > @@ -3044,8 +3048,18 @@ $(objpfx)tst-tlsgap.out: \
> >    $(objpfx)tst-tlsgap-mod0.so \
> >    $(objpfx)tst-tlsgap-mod1.so \
> >    $(objpfx)tst-tlsgap-mod2.so
> > +
> > +$(objpfx)tst-gnu2-tls2: $(shared-thread-library)
> > +$(objpfx)tst-gnu2-tls2.out: \
> > +  $(objpfx)tst-gnu2-tls2mod0.so \
> > +  $(objpfx)tst-gnu2-tls2mod1.so \
> > +  $(objpfx)tst-gnu2-tls2mod2.so
> > +
> >  ifeq (yes,$(have-mtls-dialect-gnu2))
> >  CFLAGS-tst-tlsgap-mod0.c += -mtls-dialect=gnu2
> >  CFLAGS-tst-tlsgap-mod1.c += -mtls-dialect=gnu2
> >  CFLAGS-tst-tlsgap-mod2.c += -mtls-dialect=gnu2
> > +CFLAGS-tst-gnu2-tls2mod0.c += -mtls-dialect=gnu2
> > +CFLAGS-tst-gnu2-tls2mod1.c += -mtls-dialect=gnu2
> > +CFLAGS-tst-gnu2-tls2mod2.c += -mtls-dialect=gnu2
> >  endif
> > diff --git a/elf/tst-gnu2-tls2.c b/elf/tst-gnu2-tls2.c
> > new file mode 100644
> > index 0000000000..8039ba614d
> > --- /dev/null
> > +++ b/elf/tst-gnu2-tls2.c
> > @@ -0,0 +1,120 @@
> > +/* Test TLSDESC relocation.
> > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <http://www.gnu.org/licenses/>.  */
> > +
> > +#include <stdio.h>
> > +#include <stdlib.h>
> > +#include <string.h>
> > +#include <dlfcn.h>
> > +#include <pthread.h>
> > +#include <support/xdlfcn.h>
> > +#include <support/xthread.h>
> > +#include <support/check.h>
> > +#include <support/test-driver.h>
> > +#include "tst-gnu2-tls2.h"
> > +
> > +#ifndef IS_SUPPORTED
> > +# define IS_SUPPORTED() true
> > +#endif
> > +
> > +/* An architecture can define it to clobber caller-saved registers in
> > +   malloc below to verify that the implicit TLSDESC call won't change
> > +   caller-saved registers.  */
> > +#ifndef PREPARE_MALLOC
> > +# define PREPARE_MALLOC()
> > +#endif
> > +
> > +extern void * __libc_malloc (size_t);
> > +
> > +size_t malloc_counter = 0;
> > +
> > +void *
> > +malloc (size_t n)
> > +{
> > +  PREPARE_MALLOC ();
> > +  malloc_counter++;
> > +  return __libc_malloc (n);
> > +}
> > +
> > +static void *mod[3];
> > +#define MOD(i) "tst-gnu2-tls2mod" #i ".so"
> > +static const char *modname[3] = { MOD(0), MOD(1), MOD(2) };
> > +#undef MOD
> > +
> > +static void
> > +open_mod (int i)
> > +{
> > +  mod[i] = xdlopen (modname[i], RTLD_LAZY);
> > +  printf ("open %s\n", modname[i]);
> > +}
> > +
> > +static void
> > +close_mod (int i)
> > +{
> > +  xdlclose (mod[i]);
> > +  mod[i] = NULL;
> > +  printf ("close %s\n", modname[i]);
> > +}
> > +
> > +static void
> > +access_mod (int i, const char *sym)
> > +{
> > +  struct tls var = { -1, -1, -1, -1 };
> > +  struct tls *(*f) (struct tls *) = xdlsym (mod[i], sym);
> > +  /* Check that our malloc is called.  */
> > +  malloc_counter = 0;
> > +  struct tls *p = f (&var);
> > +  TEST_VERIFY (malloc_counter != 0);
> > +  printf ("access %s: %s() = %p\n", modname[i], sym, p);
> > +  TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
> > +  ++(p->a);
> > +}
> > +
> > +static void *
> > +start (void *arg)
> > +{
> > +  /* The DTV generation is at the last dlopen of mod0 and the
> > +     entry for mod1 is NULL.  */
> > +
> > +  open_mod (1); /* Reuse modid of mod1. Uses dynamic TLS.  */
> > +
> > +  /* Force the slow path in GNU2 TLS descriptor call.  */
> > +  access_mod (1, "apply_tls");
> > +
> > +  return arg;
> > +}
> > +
> > +static int
> > +do_test (void)
> > +{
> > +  if (!IS_SUPPORTED ())
> > +    return EXIT_UNSUPPORTED;
> > +
> > +  open_mod (0);
> > +  open_mod (1);
> > +  open_mod (2);
> > +  close_mod (0);
> > +  close_mod (1); /* Create modid gap at mod1.  */
> > +  open_mod (0); /* Reuse modid of mod0, bump generation count.  */
> > +
> > +  /* Create a thread where DTV of mod1 is NULL.  */
> > +  pthread_t t = xpthread_create (NULL, start, NULL);
> > +  xpthread_join (t);
> > +  return 0;
> > +}
> > +
> > +#include <support/test-driver.c>
> > diff --git a/elf/tst-gnu2-tls2.h b/elf/tst-gnu2-tls2.h
> > new file mode 100644
> > index 0000000000..77964a57a3
> > --- /dev/null
> > +++ b/elf/tst-gnu2-tls2.h
> > @@ -0,0 +1,36 @@
> > +/* Test TLSDESC relocation.
> > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <https://www.gnu.org/licenses/>.  */
> > +
> > +#include <stdint.h>
> > +
> > +struct tls
> > +{
> > +  int64_t a, b, c, d;
> > +};
> > +
> > +extern struct tls *apply_tls (struct tls *);
> > +
> > +/* An architecture can define them to verify that clobber caller-saved
> > +   registers aren't changed by the implicit TLSDESC call.  */
> > +#ifndef BEFORE_TLSDESC_CALL
> > +# define BEFORE_TLSDESC_CALL()
> > +#endif
> > +
> > +#ifndef AFTER_TLSDESC_CALL
> > +# define AFTER_TLSDESC_CALL()
> > +#endif
> > diff --git a/elf/tst-gnu2-tls2mod0.c b/elf/tst-gnu2-tls2mod0.c
> > new file mode 100644
> > index 0000000000..20f177244d
> > --- /dev/null
> > +++ b/elf/tst-gnu2-tls2mod0.c
> > @@ -0,0 +1,31 @@
> > +/* DSO used by tst-gnu2-tls2.
> > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <https://www.gnu.org/licenses/>.  */
> > +
> > +#include "tst-gnu2-tls2.h"
> > +
> > +__thread struct tls tls_var0 __attribute__ ((visibility ("hidden")));
> > +
> > +struct tls *
> > +apply_tls (struct tls *p)
> > +{
> > +  tls_var0 = *p;
> > +  BEFORE_TLSDESC_CALL ();
> > +  struct tls *ret = &tls_var0;
> > +  AFTER_TLSDESC_CALL ();
> > +  return ret;
> > +}
> > diff --git a/elf/tst-gnu2-tls2mod1.c b/elf/tst-gnu2-tls2mod1.c
> > new file mode 100644
> > index 0000000000..86a6ee48f7
> > --- /dev/null
> > +++ b/elf/tst-gnu2-tls2mod1.c
> > @@ -0,0 +1,31 @@
> > +/* DSO used by tst-gnu2-tls2.
> > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <https://www.gnu.org/licenses/>.  */
> > +
> > +#include "tst-gnu2-tls2.h"
> > +
> > +__thread struct tls tls_var1[100] __attribute__ ((visibility ("hidden")));
> > +
> > +struct tls *
> > +apply_tls (struct tls *p)
> > +{
> > +  tls_var1[1] = *p;
> > +  BEFORE_TLSDESC_CALL ();
> > +  struct tls *ret = &tls_var1[1];
> > +  AFTER_TLSDESC_CALL ();
> > +  return ret;
> > +}
> > diff --git a/elf/tst-gnu2-tls2mod2.c b/elf/tst-gnu2-tls2mod2.c
> > new file mode 100644
> > index 0000000000..dede07599b
> > --- /dev/null
> > +++ b/elf/tst-gnu2-tls2mod2.c
> > @@ -0,0 +1,31 @@
> > +/* DSO used by tst-gnu2-tls2.
> > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <https://www.gnu.org/licenses/>.  */
> > +
> > +#include "tst-gnu2-tls2.h"
> > +
> > +__thread struct tls tls_var2 __attribute__ ((visibility ("hidden")));
> > +
> > +struct tls *
> > +apply_tls (struct tls *p)
> > +{
> > +  tls_var2 = *p;
> > +  BEFORE_TLSDESC_CALL ();
> > +  struct tls *ret = &tls_var2;
> > +  AFTER_TLSDESC_CALL ();
> > +  return ret;
> > +}
> > diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
> > index fc1ef96587..50d74fe6e9 100644
> > --- a/sysdeps/i386/dl-machine.h
> > +++ b/sysdeps/i386/dl-machine.h
> > @@ -347,7 +347,7 @@ and creates an unsatisfiable circular dependency.\n",
> >                   {
> >                     td->arg = _dl_make_tlsdesc_dynamic
> >                       (sym_map, sym->st_value + (ElfW(Word))td->arg);
> > -                   td->entry = _dl_tlsdesc_dynamic;
> > +                   td->entry = GLRO(dl_x86_tlsdesc_dynamic);
> >                   }
> >                 else
> >  #  endif
> > diff --git a/sysdeps/i386/dl-tlsdesc-dynamic.h b/sysdeps/i386/dl-tlsdesc-dynamic.h
> > new file mode 100644
> > index 0000000000..3627028577
> > --- /dev/null
> > +++ b/sysdeps/i386/dl-tlsdesc-dynamic.h
> > @@ -0,0 +1,190 @@
> > +/* Thread-local storage handling in the ELF dynamic linker.  i386 version.
> > +   Copyright (C) 2004-2024 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <https://www.gnu.org/licenses/>.  */
> > +
> > +#undef REGISTER_SAVE_AREA
> > +
> > +#if !defined USE_FNSAVE && (STATE_SAVE_ALIGNMENT % 16) != 0
> > +# error STATE_SAVE_ALIGNMENT must be multiple of 16
> > +#endif
> > +
> > +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > +# ifdef USE_FNSAVE
> > +#  error USE_FNSAVE shouldn't be defined
> > +# endif
> > +# ifdef USE_FXSAVE
> > +/* Use fxsave to save all registers.  */
> > +#  define REGISTER_SAVE_AREA   512
> > +# endif
> > +#else
> > +# ifdef USE_FNSAVE
> > +/* Use fnsave to save x87 FPU stack registers.  */
> > +#  define REGISTER_SAVE_AREA   108
> > +# else
> > +#  ifndef USE_FXSAVE
> > +#   error USE_FXSAVE must be defined
> > +#  endif
> > +/* Use fxsave to save all registers.  Add 12 bytes to align the stack
> > +   to 16 bytes.  */
> > +#  define REGISTER_SAVE_AREA   (512 + 12)
> > +# endif
> > +#endif
> > +
> > +       .hidden _dl_tlsdesc_dynamic
> > +       .global _dl_tlsdesc_dynamic
> > +       .type   _dl_tlsdesc_dynamic,@function
> > +
> > +     /* This function is used for symbols that need dynamic TLS.
> > +
> > +       %eax points to the TLS descriptor, such that 0(%eax) points to
> > +       _dl_tlsdesc_dynamic itself, and 4(%eax) points to a struct
> > +       tlsdesc_dynamic_arg object.  It must return in %eax the offset
> > +       between the thread pointer and the object denoted by the
> > +       argument, without clobbering any registers.
> > +
> > +       The assembly code that follows is a rendition of the following
> > +       C code, hand-optimized a little bit.
> > +
> > +ptrdiff_t
> > +__attribute__ ((__regparm__ (1)))
> > +_dl_tlsdesc_dynamic (struct tlsdesc *tdp)
> > +{
> > +  struct tlsdesc_dynamic_arg *td = tdp->arg;
> > +  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> > +  if (__builtin_expect (td->gen_count <= dtv[0].counter
> > +                       && (dtv[td->tlsinfo.ti_module].pointer.val
> > +                           != TLS_DTV_UNALLOCATED),
> > +                       1))
> > +    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> > +      - __thread_pointer;
> > +
> > +  return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
> > +}
> > +*/
> > +       cfi_startproc
> > +       .align 16
> > +_dl_tlsdesc_dynamic:
> > +       /* Like all TLS resolvers, preserve call-clobbered registers.
> > +          We need two scratch regs anyway.  */
> > +       subl    $32, %esp
> > +       cfi_adjust_cfa_offset (32)
> > +       movl    %ecx, 20(%esp)
> > +       movl    %edx, 24(%esp)
> > +       movl    TLSDESC_ARG(%eax), %eax
> > +       movl    %gs:DTV_OFFSET, %edx
> > +       movl    TLSDESC_GEN_COUNT(%eax), %ecx
> > +       cmpl    (%edx), %ecx
> > +       ja      2f
> > +       movl    TLSDESC_MODID(%eax), %ecx
> > +       movl    (%edx,%ecx,8), %edx
> > +       cmpl    $-1, %edx
> > +       je      2f
> > +       movl    TLSDESC_MODOFF(%eax), %eax
> > +       addl    %edx, %eax
> > +1:
> > +       movl    20(%esp), %ecx
> > +       subl    %gs:0, %eax
> > +       movl    24(%esp), %edx
> > +       addl    $32, %esp
> > +       cfi_adjust_cfa_offset (-32)
> > +       ret
> > +       .p2align 4,,7
> > +2:
> > +       cfi_adjust_cfa_offset (32)
> > +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > +       movl    %ebx, -28(%esp)
> > +       movl    %esp, %ebx
> > +       cfi_def_cfa_register(%ebx)
> > +       and     $-STATE_SAVE_ALIGNMENT, %esp
> > +#endif
> > +#ifdef REGISTER_SAVE_AREA
> > +       subl    $REGISTER_SAVE_AREA, %esp
> > +# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
> > +       cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
> > +# endif
> > +#else
> > +# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
> > +#  error DL_RUNTIME_RESOLVE_REALIGN_STACK must be true
> > +# endif
> > +       /* Allocate stack space of the required size to save the state.  */
> > +       LOAD_PIC_REG (cx)
> > +       subl    RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_SIZE_OFFSET+_rtld_local_ro@GOTOFF(%ecx), %esp
> > +#endif
> > +#ifdef USE_FNSAVE
> > +       fnsave  (%esp)
> > +#elif defined USE_FXSAVE
> > +       fxsave  (%esp)
> > +#else
> > +       /* Save the argument for ___tls_get_addr in EAX.  */
> > +       movl    %eax, %ecx
> > +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> > +       xorl    %edx, %edx
> > +       /* Clear the XSAVE Header.  */
> > +# ifdef USE_XSAVE
> > +       movl    %edx, (512)(%esp)
> > +       movl    %edx, (512 + 4 * 1)(%esp)
> > +       movl    %edx, (512 + 4 * 2)(%esp)
> > +       movl    %edx, (512 + 4 * 3)(%esp)
> > +# endif
> > +       movl    %edx, (512 + 4 * 4)(%esp)
> > +       movl    %edx, (512 + 4 * 5)(%esp)
> > +       movl    %edx, (512 + 4 * 6)(%esp)
> > +       movl    %edx, (512 + 4 * 7)(%esp)
> > +       movl    %edx, (512 + 4 * 8)(%esp)
> > +       movl    %edx, (512 + 4 * 9)(%esp)
> > +       movl    %edx, (512 + 4 * 10)(%esp)
> > +       movl    %edx, (512 + 4 * 11)(%esp)
> > +       movl    %edx, (512 + 4 * 12)(%esp)
> > +       movl    %edx, (512 + 4 * 13)(%esp)
> > +       movl    %edx, (512 + 4 * 14)(%esp)
> > +       movl    %edx, (512 + 4 * 15)(%esp)
> > +# ifdef USE_XSAVE
> > +       xsave   (%esp)
> > +# else
> > +       xsavec  (%esp)
> > +# endif
> > +       /* Restore the argument for ___tls_get_addr in EAX.  */
> > +       movl    %ecx, %eax
> > +#endif
> > +       call    HIDDEN_JUMPTARGET (___tls_get_addr)
> > +       /* Get register content back.  */
> > +#ifdef USE_FNSAVE
> > +       frstor  (%esp)
> > +#elif defined USE_FXSAVE
> > +       fxrstor (%esp)
> > +#else
> > +       /* Save and retore ___tls_get_addr return value stored in EAX.  */
> > +       movl    %eax, %ecx
> > +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> > +       xorl    %edx, %edx
> > +       xrstor  (%esp)
> > +       movl    %ecx, %eax
> > +#endif
> > +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > +       mov     %ebx, %esp
> > +       cfi_def_cfa_register(%esp)
> > +       movl    -28(%esp), %ebx
> > +       cfi_restore(%ebx)
> > +#else
> > +       addl    $REGISTER_SAVE_AREA, %esp
> > +       cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
> > +#endif
> > +       jmp     1b
> > +       cfi_endproc
> > +       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> > +
> > +#undef STATE_SAVE_ALIGNMENT
> > diff --git a/sysdeps/i386/dl-tlsdesc.S b/sysdeps/i386/dl-tlsdesc.S
> > index 90d93caa0c..f002feee56 100644
> > --- a/sysdeps/i386/dl-tlsdesc.S
> > +++ b/sysdeps/i386/dl-tlsdesc.S
> > @@ -18,8 +18,27 @@
> >
> >  #include <sysdep.h>
> >  #include <tls.h>
> > +#include <cpu-features-offsets.h>
> > +#include <features-offsets.h>
> >  #include "tlsdesc.h"
> >
> > +#ifndef DL_STACK_ALIGNMENT
> > +/* Due to GCC bug:
> > +
> > +   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> > +
> > +   __tls_get_addr may be called with 4-byte stack alignment.  Although
> > +   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
> > +   that stack will be always aligned at 16 bytes.  */
> > +# define DL_STACK_ALIGNMENT 4
> > +#endif
> > +
> > +/* True if _dl_tlsdesc_dynamic should align stack for STATE_SAVE or align
> > +   stack to MINIMUM_ALIGNMENT bytes before calling ___tls_get_addr.  */
> > +#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> > +  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> > +   || MINIMUM_ALIGNMENT > DL_STACK_ALIGNMENT)
> > +
> >         .text
> >
> >       /* This function is used to compute the TP offset for symbols in
> > @@ -65,69 +84,35 @@ _dl_tlsdesc_undefweak:
> >         .size   _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
> >
> >  #ifdef SHARED
> > -       .hidden _dl_tlsdesc_dynamic
> > -       .global _dl_tlsdesc_dynamic
> > -       .type   _dl_tlsdesc_dynamic,@function
> > -
> > -     /* This function is used for symbols that need dynamic TLS.
> > -
> > -       %eax points to the TLS descriptor, such that 0(%eax) points to
> > -       _dl_tlsdesc_dynamic itself, and 4(%eax) points to a struct
> > -       tlsdesc_dynamic_arg object.  It must return in %eax the offset
> > -       between the thread pointer and the object denoted by the
> > -       argument, without clobbering any registers.
> > -
> > -       The assembly code that follows is a rendition of the following
> > -       C code, hand-optimized a little bit.
> > -
> > -ptrdiff_t
> > -__attribute__ ((__regparm__ (1)))
> > -_dl_tlsdesc_dynamic (struct tlsdesc *tdp)
> > -{
> > -  struct tlsdesc_dynamic_arg *td = tdp->arg;
> > -  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> > -  if (__builtin_expect (td->gen_count <= dtv[0].counter
> > -                       && (dtv[td->tlsinfo.ti_module].pointer.val
> > -                           != TLS_DTV_UNALLOCATED),
> > -                       1))
> > -    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> > -      - __thread_pointer;
> > -
> > -  return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
> > -}
> > -*/
> > -       cfi_startproc
> > -       .align 16
> > -_dl_tlsdesc_dynamic:
> > -       /* Like all TLS resolvers, preserve call-clobbered registers.
> > -          We need two scratch regs anyway.  */
> > -       subl    $28, %esp
> > -       cfi_adjust_cfa_offset (28)
> > -       movl    %ecx, 20(%esp)
> > -       movl    %edx, 24(%esp)
> > -       movl    TLSDESC_ARG(%eax), %eax
> > -       movl    %gs:DTV_OFFSET, %edx
> > -       movl    TLSDESC_GEN_COUNT(%eax), %ecx
> > -       cmpl    (%edx), %ecx
> > -       ja      .Lslow
> > -       movl    TLSDESC_MODID(%eax), %ecx
> > -       movl    (%edx,%ecx,8), %edx
> > -       cmpl    $-1, %edx
> > -       je      .Lslow
> > -       movl    TLSDESC_MODOFF(%eax), %eax
> > -       addl    %edx, %eax
> > -.Lret:
> > -       movl    20(%esp), %ecx
> > -       subl    %gs:0, %eax
> > -       movl    24(%esp), %edx
> > -       addl    $28, %esp
> > -       cfi_adjust_cfa_offset (-28)
> > -       ret
> > -       .p2align 4,,7
> > -.Lslow:
> > -       cfi_adjust_cfa_offset (28)
> > -       call    HIDDEN_JUMPTARGET (___tls_get_addr)
> > -       jmp     .Lret
> > -       cfi_endproc
> > -       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> > +# define USE_FNSAVE
> > +# define MINIMUM_ALIGNMENT     4
> > +# define STATE_SAVE_ALIGNMENT  4
> > +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_fnsave
> > +# include "dl-tlsdesc-dynamic.h"
> > +# undef _dl_tlsdesc_dynamic
> > +# undef MINIMUM_ALIGNMENT
> > +# undef USE_FNSAVE
> > +
> > +# define MINIMUM_ALIGNMENT     16
> > +
> > +# define USE_FXSAVE
> > +# define STATE_SAVE_ALIGNMENT  16
> > +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_fxsave
> > +# include "dl-tlsdesc-dynamic.h"
> > +# undef _dl_tlsdesc_dynamic
> > +# undef USE_FXSAVE
> > +
> > +# define USE_XSAVE
> > +# define STATE_SAVE_ALIGNMENT  64
> > +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsave
> > +# include "dl-tlsdesc-dynamic.h"
> > +# undef _dl_tlsdesc_dynamic
> > +# undef USE_XSAVE
> > +
> > +# define USE_XSAVEC
> > +# define STATE_SAVE_ALIGNMENT  64
> > +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsavec
> > +# include "dl-tlsdesc-dynamic.h"
> > +# undef _dl_tlsdesc_dynamic
> > +# undef USE_XSAVEC
> >  #endif /* SHARED */
> > diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
> > index 73b29cc78c..5311b594af 100644
> > --- a/sysdeps/x86/Makefile
> > +++ b/sysdeps/x86/Makefile
> > @@ -1,5 +1,5 @@
> >  ifeq ($(subdir),csu)
> > -gen-as-const-headers += cpu-features-offsets.sym
> > +gen-as-const-headers += cpu-features-offsets.sym features-offsets.sym
> >  endif
> >
> >  ifeq ($(subdir),elf)
> > @@ -86,6 +86,11 @@ endif
> >  tst-ifunc-isa-2-ENV = GLIBC_TUNABLES=glibc.cpu.hwcaps=-SSE4_2,-AVX,-AVX2,-AVX512F
> >  tst-ifunc-isa-2-static-ENV = $(tst-ifunc-isa-2-ENV)
> >  tst-hwcap-tunables-ARGS = -- $(host-test-program-cmd)
> > +
> > +CFLAGS-tst-gnu2-tls2.c += -msse
> > +CFLAGS-tst-gnu2-tls2mod0.c += -msse2 -mtune=haswell
> > +CFLAGS-tst-gnu2-tls2mod1.c += -msse2 -mtune=haswell
> > +CFLAGS-tst-gnu2-tls2mod2.c += -msse2 -mtune=haswell
> >  endif
> >
> >  ifeq ($(subdir),math)
> > diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> > index 25e6622a79..835113b42f 100644
> > --- a/sysdeps/x86/cpu-features.c
> > +++ b/sysdeps/x86/cpu-features.c
> > @@ -27,8 +27,13 @@
> >  extern void TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *)
> >    attribute_hidden;
> >
> > -#if defined SHARED && defined __x86_64__
> > -# include <dl-plt-rewrite.h>
> > +#if defined SHARED
> > +extern void _dl_tlsdesc_dynamic_fxsave (void) attribute_hidden;
> > +extern void _dl_tlsdesc_dynamic_xsave (void) attribute_hidden;
> > +extern void _dl_tlsdesc_dynamic_xsavec (void) attribute_hidden;
> > +
> > +# ifdef __x86_64__
> > +#  include <dl-plt-rewrite.h>
> >
> >  static void
> >  TUNABLE_CALLBACK (set_plt_rewrite) (tunable_val_t *valp)
> > @@ -47,6 +52,15 @@ TUNABLE_CALLBACK (set_plt_rewrite) (tunable_val_t *valp)
> >                  : plt_rewrite_jmp);
> >      }
> >  }
> > +# else
> > +extern void _dl_tlsdesc_dynamic_fnsave (void) attribute_hidden;
> > +# endif
> > +#endif
> > +
> > +#ifdef __x86_64__
> > +extern void _dl_runtime_resolve_fxsave (void) attribute_hidden;
> > +extern void _dl_runtime_resolve_xsave (void) attribute_hidden;
> > +extern void _dl_runtime_resolve_xsavec (void) attribute_hidden;
> >  #endif
> >
> >  #ifdef __LP64__
> > @@ -1130,6 +1144,44 @@ no_cpuid:
> >                TUNABLE_CALLBACK (set_x86_shstk));
> >  #endif
> >
> > +  if (GLRO(dl_x86_cpu_features).xsave_state_size != 0)
> > +    {
> > +      if (CPU_FEATURE_USABLE_P (cpu_features, XSAVEC))
> > +       {
> > +#ifdef __x86_64__
> > +         GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_xsavec;
> > +#endif
> > +#ifdef SHARED
> > +         GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_xsavec;
> > +#endif
> > +       }
> > +      else
> > +       {
> > +#ifdef __x86_64__
> > +         GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_xsave;
> > +#endif
> > +#ifdef SHARED
> > +         GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_xsave;
> > +#endif
> > +       }
> > +    }
> > +  else
> > +    {
> > +#ifdef __x86_64__
> > +      GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_fxsave;
> > +# ifdef SHARED
> > +      GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fxsave;
> > +# endif
> > +#else
> > +# ifdef SHARED
> > +      if (CPU_FEATURE_USABLE_P (cpu_features, FXSR))
> > +       GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fxsave;
> > +      else
> > +       GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fnsave;
> > +# endif
> > +#endif
> > +    }
> > +
> >  #ifdef SHARED
> >  # ifdef __x86_64__
> >    TUNABLE_GET (plt_rewrite, tunable_val_t *,
> > diff --git a/sysdeps/x86/dl-procinfo.c b/sysdeps/x86/dl-procinfo.c
> > index ee957b4d70..5920d4b320 100644
> > --- a/sysdeps/x86/dl-procinfo.c
> > +++ b/sysdeps/x86/dl-procinfo.c
> > @@ -86,3 +86,19 @@ PROCINFO_CLASS const char _dl_x86_platforms[4][9]
> >  #else
> >  ,
> >  #endif
> > +
> > +#if defined SHARED && !IS_IN (ldconfig)
> > +# if !defined PROCINFO_DECL
> > +  ._dl_x86_tlsdesc_dynamic
> > +# else
> > +PROCINFO_CLASS void * _dl_x86_tlsdesc_dynamic
> > +# endif
> > +# ifndef PROCINFO_DECL
> > += NULL
> > +# endif
> > +# ifdef PROCINFO_DECL
> > +;
> > +# else
> > +,
> > +# endif
> > +#endif
> > diff --git a/sysdeps/x86_64/features-offsets.sym b/sysdeps/x86/features-offsets.sym
> > similarity index 89%
> > rename from sysdeps/x86_64/features-offsets.sym
> > rename to sysdeps/x86/features-offsets.sym
> > index 9e4be3393a..77e990c705 100644
> > --- a/sysdeps/x86_64/features-offsets.sym
> > +++ b/sysdeps/x86/features-offsets.sym
> > @@ -3,4 +3,6 @@
> >  #include <ldsodefs.h>
> >
> >  RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET offsetof (struct rtld_global_ro, _dl_x86_cpu_features)
> > +#ifdef __x86_64__
> >  RTLD_GLOBAL_DL_X86_FEATURE_1_OFFSET offsetof (struct rtld_global, _dl_x86_feature_1)
> > +#endif
> > diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
> > index 837fd28734..485cad9c02 100644
> > --- a/sysdeps/x86/sysdep.h
> > +++ b/sysdeps/x86/sysdep.h
> > @@ -70,6 +70,12 @@
> >     | (1 << X86_XSTATE_ZMM_H_ID))
> >  #endif
> >
> > +/* States which should be saved for TLSDESC_CALL and TLS_DESC_CALL.
> > +   Compiler assumes that all registers, including x87 FPU stack registers,
> > +   are unchanged after CALL, except for EFLAGS and RAX/EAX.  */
> > +#define TLSDESC_CALL_STATE_SAVE_MASK   \
> > +  (STATE_SAVE_MASK | (1 << X86_XSTATE_X87_ID))
> > +
> >  /* Constants for bits in __x86_string_control:  */
> >
> >  /* Avoid short distance REP MOVSB.  */
> > diff --git a/sysdeps/x86/tst-gnu2-tls2.c b/sysdeps/x86/tst-gnu2-tls2.c
> > new file mode 100644
> > index 0000000000..de900a423b
> > --- /dev/null
> > +++ b/sysdeps/x86/tst-gnu2-tls2.c
> > @@ -0,0 +1,20 @@
> > +#ifndef __x86_64__
> > +#include <sys/platform/x86.h>
> > +
> > +#define IS_SUPPORTED() CPU_FEATURE_ACTIVE (SSE2)
> > +#endif
> > +
> > +/* Clear XMM0...XMM7  */
> > +#define PREPARE_MALLOC()                               \
> > +{                                                      \
> > +  asm volatile ("xorps %%xmm0, %%xmm0" : : : "xmm0" ); \
> > +  asm volatile ("xorps %%xmm1, %%xmm1" : : : "xmm1" ); \
> > +  asm volatile ("xorps %%xmm2, %%xmm2" : : : "xmm2" ); \
> > +  asm volatile ("xorps %%xmm3, %%xmm3" : : : "xmm3" ); \
> > +  asm volatile ("xorps %%xmm4, %%xmm4" : : : "xmm4" ); \
> > +  asm volatile ("xorps %%xmm5, %%xmm5" : : : "xmm5" ); \
> > +  asm volatile ("xorps %%xmm6, %%xmm6" : : : "xmm6" ); \
> > +  asm volatile ("xorps %%xmm7, %%xmm7" : : : "xmm7" ); \
> > +}
> > +
> > +#include <elf/tst-gnu2-tls2.c>
> > diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile
> > index 145f25e7f6..9337e95093 100644
> > --- a/sysdeps/x86_64/Makefile
> > +++ b/sysdeps/x86_64/Makefile
> > @@ -10,7 +10,7 @@ LDFLAGS-rtld += -Wl,-z,nomark-plt
> >  endif
> >
> >  ifeq ($(subdir),csu)
> > -gen-as-const-headers += features-offsets.sym link-defines.sym
> > +gen-as-const-headers += link-defines.sym
> >  endif
> >
> >  ifeq ($(subdir),gmon)
> > diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
> > index 6d605d0d32..ff5d45f7cb 100644
> > --- a/sysdeps/x86_64/dl-machine.h
> > +++ b/sysdeps/x86_64/dl-machine.h
> > @@ -71,9 +71,6 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
> >                            int lazy, int profile)
> >  {
> >    Elf64_Addr *got;
> > -  extern void _dl_runtime_resolve_fxsave (ElfW(Word)) attribute_hidden;
> > -  extern void _dl_runtime_resolve_xsave (ElfW(Word)) attribute_hidden;
> > -  extern void _dl_runtime_resolve_xsavec (ElfW(Word)) attribute_hidden;
> >    extern void _dl_runtime_profile_sse (ElfW(Word)) attribute_hidden;
> >    extern void _dl_runtime_profile_avx (ElfW(Word)) attribute_hidden;
> >    extern void _dl_runtime_profile_avx512 (ElfW(Word)) attribute_hidden;
> > @@ -96,8 +93,6 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
> >        /* Identify this shared object.  */
> >        *(ElfW(Addr) *) (got + 1) = (ElfW(Addr)) l;
> >
> > -      const struct cpu_features* cpu_features = __get_cpu_features ();
> > -
> >  #ifdef SHARED
> >        /* The got[2] entry contains the address of a function which gets
> >          called to get the address of a so far unresolved function and
> > @@ -107,6 +102,7 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
> >          end in this function.  */
> >        if (__glibc_unlikely (profile))
> >         {
> > +         const struct cpu_features* cpu_features = __get_cpu_features ();
> >           if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512F))
> >             *(ElfW(Addr) *) (got + 2) = (ElfW(Addr)) &_dl_runtime_profile_avx512;
> >           else if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX))
> > @@ -126,15 +122,8 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
> >           /* This function will get called to fix up the GOT entry
> >              indicated by the offset on the stack, and then jump to
> >              the resolved address.  */
> > -         if (MINIMUM_X86_ISA_LEVEL >= AVX_X86_ISA_LEVEL
> > -             || GLRO(dl_x86_cpu_features).xsave_state_size != 0)
> > -           *(ElfW(Addr) *) (got + 2)
> > -             = (CPU_FEATURE_USABLE_P (cpu_features, XSAVEC)
> > -                ? (ElfW(Addr)) &_dl_runtime_resolve_xsavec
> > -                : (ElfW(Addr)) &_dl_runtime_resolve_xsave);
> > -         else
> > -           *(ElfW(Addr) *) (got + 2)
> > -             = (ElfW(Addr)) &_dl_runtime_resolve_fxsave;
> > +         *(ElfW(Addr) *) (got + 2)
> > +           = (ElfW(Addr)) GLRO(dl_x86_64_runtime_resolve);
> >         }
> >      }
> >
> > @@ -383,7 +372,7 @@ and creates an unsatisfiable circular dependency.\n",
> >                   {
> >                     td->arg = _dl_make_tlsdesc_dynamic
> >                       (sym_map, sym->st_value + reloc->r_addend);
> > -                   td->entry = _dl_tlsdesc_dynamic;
> > +                   td->entry = GLRO(dl_x86_tlsdesc_dynamic);
> >                   }
> >                 else
> >  #  endif
> > diff --git a/sysdeps/x86_64/dl-procinfo.c b/sysdeps/x86_64/dl-procinfo.c
> > index 4d1d790fbb..06637a8154 100644
> > --- a/sysdeps/x86_64/dl-procinfo.c
> > +++ b/sysdeps/x86_64/dl-procinfo.c
> > @@ -41,5 +41,21 @@
> >
> >  #include <sysdeps/x86/dl-procinfo.c>
> >
> > +#if !IS_IN (ldconfig)
> > +# if !defined PROCINFO_DECL && defined SHARED
> > +  ._dl_x86_64_runtime_resolve
> > +# else
> > +PROCINFO_CLASS void * _dl_x86_64_runtime_resolve
> > +# endif
> > +# ifndef PROCINFO_DECL
> > += NULL
> > +# endif
> > +# if !defined SHARED || defined PROCINFO_DECL
> > +;
> > +# else
> > +,
> > +# endif
> > +#endif
> > +
> >  #undef PROCINFO_DECL
> >  #undef PROCINFO_CLASS
> > diff --git a/sysdeps/x86_64/dl-tlsdesc-dynamic.h b/sysdeps/x86_64/dl-tlsdesc-dynamic.h
> > new file mode 100644
> > index 0000000000..0c2e8d5320
> > --- /dev/null
> > +++ b/sysdeps/x86_64/dl-tlsdesc-dynamic.h
> > @@ -0,0 +1,166 @@
> > +/* Thread-local storage handling in the ELF dynamic linker.  x86_64 version.
> > +   Copyright (C) 2004-2024 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <https://www.gnu.org/licenses/>.  */
> > +
> > +#ifndef SECTION
> > +# define SECTION(p)    p
> > +#endif
> > +
> > +#undef REGISTER_SAVE_AREA
> > +#undef LOCAL_STORAGE_AREA
> > +#undef BASE
> > +
> > +#include "dl-trampoline-state.h"
> > +
> > +       .section SECTION(.text),"ax",@progbits
> > +
> > +       .hidden _dl_tlsdesc_dynamic
> > +       .global _dl_tlsdesc_dynamic
> > +       .type   _dl_tlsdesc_dynamic,@function
> > +
> > +     /* %rax points to the TLS descriptor, such that 0(%rax) points to
> > +       _dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct
> > +       tlsdesc_dynamic_arg object.  It must return in %rax the offset
> > +       between the thread pointer and the object denoted by the
> > +       argument, without clobbering any registers.
> > +
> > +       The assembly code that follows is a rendition of the following
> > +       C code, hand-optimized a little bit.
> > +
> > +ptrdiff_t
> > +_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax"))
> > +{
> > +  struct tlsdesc_dynamic_arg *td = tdp->arg;
> > +  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> > +  if (__builtin_expect (td->gen_count <= dtv[0].counter
> > +                       && (dtv[td->tlsinfo.ti_module].pointer.val
> > +                           != TLS_DTV_UNALLOCATED),
> > +                       1))
> > +    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> > +      - __thread_pointer;
> > +
> > +  return __tls_get_addr_internal (&td->tlsinfo) - __thread_pointer;
> > +}
> > +*/
> > +       cfi_startproc
> > +       .align 16
> > +_dl_tlsdesc_dynamic:
> > +       _CET_ENDBR
> > +       /* Preserve call-clobbered registers that we modify.
> > +          We need two scratch regs anyway.  */
> > +       movq    %rsi, -16(%rsp)
> > +       mov     %fs:DTV_OFFSET, %RSI_LP
> > +       movq    %rdi, -8(%rsp)
> > +       movq    TLSDESC_ARG(%rax), %rdi
> > +       movq    (%rsi), %rax
> > +       cmpq    %rax, TLSDESC_GEN_COUNT(%rdi)
> > +       ja      2f
> > +       movq    TLSDESC_MODID(%rdi), %rax
> > +       salq    $4, %rax
> > +       movq    (%rax,%rsi), %rax
> > +       cmpq    $-1, %rax
> > +       je      2f
> > +       addq    TLSDESC_MODOFF(%rdi), %rax
> > +1:
> > +       movq    -16(%rsp), %rsi
> > +       sub     %fs:0, %RAX_LP
> > +       movq    -8(%rsp), %rdi
> > +       ret
> > +2:
> > +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > +       movq    %rbx, -24(%rsp)
> > +       mov     %RSP_LP, %RBX_LP
> > +       cfi_def_cfa_register(%rbx)
> > +       and     $-STATE_SAVE_ALIGNMENT, %RSP_LP
> > +#endif
> > +#ifdef REGISTER_SAVE_AREA
> > +# if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > +       /* STATE_SAVE_OFFSET has space for 8 integer registers.  But we
> > +          need space for RCX, RDX, RSI, RDI, R8, R9, R10 and R11, plus
> > +          RBX above.  */
> > +       sub     $(REGISTER_SAVE_AREA + STATE_SAVE_ALIGNMENT), %RSP_LP
> > +# else
> > +       sub     $REGISTER_SAVE_AREA, %RSP_LP
> > +       cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
> > +# endif
> > +#else
> > +       /* Allocate stack space of the required size to save the state.  */
> > +       sub     _rtld_local_ro+RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_SIZE_OFFSET(%rip), %RSP_LP
> > +#endif
> > +       /* Besides rdi and rsi, saved above, save rcx, rdx, r8, r9,
> > +          r10 and r11.  */
> > +       movq    %rcx, REGISTER_SAVE_RCX(%rsp)
> > +       movq    %rdx, REGISTER_SAVE_RDX(%rsp)
> > +       movq    %r8, REGISTER_SAVE_R8(%rsp)
> > +       movq    %r9, REGISTER_SAVE_R9(%rsp)
> > +       movq    %r10, REGISTER_SAVE_R10(%rsp)
> > +       movq    %r11, REGISTER_SAVE_R11(%rsp)
> > +#ifdef USE_FXSAVE
> > +       fxsave  STATE_SAVE_OFFSET(%rsp)
> > +#else
> > +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> > +       xorl    %edx, %edx
> > +       /* Clear the XSAVE Header.  */
> > +# ifdef USE_XSAVE
> > +       movq    %rdx, (STATE_SAVE_OFFSET + 512)(%rsp)
> > +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8)(%rsp)
> > +# endif
> > +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 2)(%rsp)
> > +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 3)(%rsp)
> > +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 4)(%rsp)
> > +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 5)(%rsp)
> > +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 6)(%rsp)
> > +       movq    %rdx, (STATE_SAVE_OFFSET + 512 + 8 * 7)(%rsp)
> > +# ifdef USE_XSAVE
> > +       xsave   STATE_SAVE_OFFSET(%rsp)
> > +# else
> > +       xsavec  STATE_SAVE_OFFSET(%rsp)
> > +# endif
> > +#endif
> > +       /* %rdi already points to the tlsinfo data structure.  */
> > +       call    HIDDEN_JUMPTARGET (__tls_get_addr)
> > +       # Get register content back.
> > +#ifdef USE_FXSAVE
> > +       fxrstor STATE_SAVE_OFFSET(%rsp)
> > +#else
> > +       /* Save and retore __tls_get_addr return value stored in RAX.  */
> > +       mov     %RAX_LP, %RCX_LP
> > +       movl    $TLSDESC_CALL_STATE_SAVE_MASK, %eax
> > +       xorl    %edx, %edx
> > +       xrstor  STATE_SAVE_OFFSET(%rsp)
> > +       mov     %RCX_LP, %RAX_LP
> > +#endif
> > +       movq    REGISTER_SAVE_R11(%rsp), %r11
> > +       movq    REGISTER_SAVE_R10(%rsp), %r10
> > +       movq    REGISTER_SAVE_R9(%rsp), %r9
> > +       movq    REGISTER_SAVE_R8(%rsp), %r8
> > +       movq    REGISTER_SAVE_RDX(%rsp), %rdx
> > +       movq    REGISTER_SAVE_RCX(%rsp), %rcx
> > +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > +       mov     %RBX_LP, %RSP_LP
> > +       cfi_def_cfa_register(%rsp)
> > +       movq    -24(%rsp), %rbx
> > +       cfi_restore(%rbx)
> > +#else
> > +       add     $REGISTER_SAVE_AREA, %RSP_LP
> > +       cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
> > +#endif
> > +       jmp     1b
> > +       cfi_endproc
> > +       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> > +
> > +#undef STATE_SAVE_ALIGNMENT
> > diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S
> > index f748af2ece..ea69f5223a 100644
> > --- a/sysdeps/x86_64/dl-tlsdesc.S
> > +++ b/sysdeps/x86_64/dl-tlsdesc.S
> > @@ -18,7 +18,19 @@
> >
> >  #include <sysdep.h>
> >  #include <tls.h>
> > +#include <cpu-features-offsets.h>
> > +#include <features-offsets.h>
> >  #include "tlsdesc.h"
> > +#include "dl-trampoline-save.h"
> > +
> > +/* Area on stack to save and restore registers used for parameter
> > +   passing when calling _dl_tlsdesc_dynamic.  */
> > +#define REGISTER_SAVE_RCX      0
> > +#define REGISTER_SAVE_RDX      (REGISTER_SAVE_RCX + 8)
> > +#define REGISTER_SAVE_R8       (REGISTER_SAVE_RDX + 8)
> > +#define REGISTER_SAVE_R9       (REGISTER_SAVE_R8 + 8)
> > +#define REGISTER_SAVE_R10      (REGISTER_SAVE_R9 + 8)
> > +#define REGISTER_SAVE_R11      (REGISTER_SAVE_R10 + 8)
> >
> >         .text
> >
> > @@ -67,80 +79,24 @@ _dl_tlsdesc_undefweak:
> >         .size   _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
> >
> >  #ifdef SHARED
> > -       .hidden _dl_tlsdesc_dynamic
> > -       .global _dl_tlsdesc_dynamic
> > -       .type   _dl_tlsdesc_dynamic,@function
> > -
> > -     /* %rax points to the TLS descriptor, such that 0(%rax) points to
> > -       _dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct
> > -       tlsdesc_dynamic_arg object.  It must return in %rax the offset
> > -       between the thread pointer and the object denoted by the
> > -       argument, without clobbering any registers.
> > -
> > -       The assembly code that follows is a rendition of the following
> > -       C code, hand-optimized a little bit.
> > -
> > -ptrdiff_t
> > -_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax"))
> > -{
> > -  struct tlsdesc_dynamic_arg *td = tdp->arg;
> > -  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
> > -  if (__builtin_expect (td->gen_count <= dtv[0].counter
> > -                       && (dtv[td->tlsinfo.ti_module].pointer.val
> > -                           != TLS_DTV_UNALLOCATED),
> > -                       1))
> > -    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
> > -      - __thread_pointer;
> > -
> > -  return __tls_get_addr_internal (&td->tlsinfo) - __thread_pointer;
> > -}
> > -*/
> > -       cfi_startproc
> > -       .align 16
> > -_dl_tlsdesc_dynamic:
> > -       _CET_ENDBR
> > -       /* Preserve call-clobbered registers that we modify.
> > -          We need two scratch regs anyway.  */
> > -       movq    %rsi, -16(%rsp)
> > -       mov     %fs:DTV_OFFSET, %RSI_LP
> > -       movq    %rdi, -8(%rsp)
> > -       movq    TLSDESC_ARG(%rax), %rdi
> > -       movq    (%rsi), %rax
> > -       cmpq    %rax, TLSDESC_GEN_COUNT(%rdi)
> > -       ja      .Lslow
> > -       movq    TLSDESC_MODID(%rdi), %rax
> > -       salq    $4, %rax
> > -       movq    (%rax,%rsi), %rax
> > -       cmpq    $-1, %rax
> > -       je      .Lslow
> > -       addq    TLSDESC_MODOFF(%rdi), %rax
> > -.Lret:
> > -       movq    -16(%rsp), %rsi
> > -       sub     %fs:0, %RAX_LP
> > -       movq    -8(%rsp), %rdi
> > -       ret
> > -.Lslow:
> > -       /* Besides rdi and rsi, saved above, save rdx, rcx, r8, r9,
> > -          r10 and r11.  Also, align the stack, that's off by 8 bytes.  */
> > -       subq    $72, %rsp
> > -       cfi_adjust_cfa_offset (72)
> > -       movq    %rdx, 8(%rsp)
> > -       movq    %rcx, 16(%rsp)
> > -       movq    %r8, 24(%rsp)
> > -       movq    %r9, 32(%rsp)
> > -       movq    %r10, 40(%rsp)
> > -       movq    %r11, 48(%rsp)
> > -       /* %rdi already points to the tlsinfo data structure.  */
> > -       call    HIDDEN_JUMPTARGET (__tls_get_addr)
> > -       movq    8(%rsp), %rdx
> > -       movq    16(%rsp), %rcx
> > -       movq    24(%rsp), %r8
> > -       movq    32(%rsp), %r9
> > -       movq    40(%rsp), %r10
> > -       movq    48(%rsp), %r11
> > -       addq    $72, %rsp
> > -       cfi_adjust_cfa_offset (-72)
> > -       jmp     .Lret
> > -       cfi_endproc
> > -       .size   _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
> > +# define USE_FXSAVE
> > +# define STATE_SAVE_ALIGNMENT  16
> > +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_fxsave
> > +# include "dl-tlsdesc-dynamic.h"
> > +# undef _dl_tlsdesc_dynamic
> > +# undef USE_FXSAVE
> > +
> > +# define USE_XSAVE
> > +# define STATE_SAVE_ALIGNMENT  64
> > +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsave
> > +# include "dl-tlsdesc-dynamic.h"
> > +# undef _dl_tlsdesc_dynamic
> > +# undef USE_XSAVE
> > +
> > +# define USE_XSAVEC
> > +# define STATE_SAVE_ALIGNMENT  64
> > +# define _dl_tlsdesc_dynamic   _dl_tlsdesc_dynamic_xsavec
> > +# include "dl-tlsdesc-dynamic.h"
> > +# undef _dl_tlsdesc_dynamic
> > +# undef USE_XSAVEC
> >  #endif /* SHARED */
> > diff --git a/sysdeps/x86_64/dl-trampoline-save.h b/sysdeps/x86_64/dl-trampoline-save.h
> > new file mode 100644
> > index 0000000000..84eac4a8ac
> > --- /dev/null
> > +++ b/sysdeps/x86_64/dl-trampoline-save.h
> > @@ -0,0 +1,34 @@
> > +/* x86-64 PLT trampoline register save macros.
> > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <https://www.gnu.org/licenses/>.  */
> > +
> > +#ifndef DL_STACK_ALIGNMENT
> > +/* Due to GCC bug:
> > +
> > +   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> > +
> > +   __tls_get_addr may be called with 8-byte stack alignment.  Although
> > +   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
> > +   that stack will be always aligned at 16 bytes.  */
> > +# define DL_STACK_ALIGNMENT 8
> > +#endif
> > +
> > +/* True if _dl_runtime_resolve should align stack for STATE_SAVE or align
> > +   stack to 16 bytes before calling _dl_fixup.  */
> > +#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> > +  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> > +   || 16 > DL_STACK_ALIGNMENT)
> > diff --git a/sysdeps/x86_64/dl-trampoline-state.h b/sysdeps/x86_64/dl-trampoline-state.h
> > new file mode 100644
> > index 0000000000..575f120797
> > --- /dev/null
> > +++ b/sysdeps/x86_64/dl-trampoline-state.h
> > @@ -0,0 +1,51 @@
> > +/* x86-64 PLT dl-trampoline state macros.
> > +   Copyright (C) 2024 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <https://www.gnu.org/licenses/>.  */
> > +
> > +#if (STATE_SAVE_ALIGNMENT % 16) != 0
> > +# error STATE_SAVE_ALIGNMENT must be multiple of 16
> > +#endif
> > +
> > +#if (STATE_SAVE_OFFSET % STATE_SAVE_ALIGNMENT) != 0
> > +# error STATE_SAVE_OFFSET must be multiple of STATE_SAVE_ALIGNMENT
> > +#endif
> > +
> > +#if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > +/* Local stack area before jumping to function address: RBX.  */
> > +# define LOCAL_STORAGE_AREA    8
> > +# define BASE                  rbx
> > +# ifdef USE_FXSAVE
> > +/* Use fxsave to save XMM registers.  */
> > +#  define REGISTER_SAVE_AREA   (512 + STATE_SAVE_OFFSET)
> > +#  if (REGISTER_SAVE_AREA % 16) != 0
> > +#   error REGISTER_SAVE_AREA must be multiple of 16
> > +#  endif
> > +# endif
> > +#else
> > +# ifndef USE_FXSAVE
> > +#  error USE_FXSAVE must be defined
> > +# endif
> > +/* Use fxsave to save XMM registers.  */
> > +# define REGISTER_SAVE_AREA    (512 + STATE_SAVE_OFFSET + 8)
> > +/* Local stack area before jumping to function address:  All saved
> > +   registers.  */
> > +# define LOCAL_STORAGE_AREA    REGISTER_SAVE_AREA
> > +# define BASE                  rsp
> > +# if (REGISTER_SAVE_AREA % 16) != 8
> > +#  error REGISTER_SAVE_AREA must be odd multiple of 8
> > +# endif
> > +#endif
> > diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S
> > index b2e7e0f69b..87c5137837 100644
> > --- a/sysdeps/x86_64/dl-trampoline.S
> > +++ b/sysdeps/x86_64/dl-trampoline.S
> > @@ -22,25 +22,7 @@
> >  #include <features-offsets.h>
> >  #include <link-defines.h>
> >  #include <isa-level.h>
> > -
> > -#ifndef DL_STACK_ALIGNMENT
> > -/* Due to GCC bug:
> > -
> > -   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
> > -
> > -   __tls_get_addr may be called with 8-byte stack alignment.  Although
> > -   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
> > -   that stack will be always aligned at 16 bytes.  We use unaligned
> > -   16-byte move to load and store SSE registers, which has no penalty
> > -   on modern processors if stack is 16-byte aligned.  */
> > -# define DL_STACK_ALIGNMENT 8
> > -#endif
> > -
> > -/* True if _dl_runtime_resolve should align stack for STATE_SAVE or align
> > -   stack to 16 bytes before calling _dl_fixup.  */
> > -#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
> > -  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
> > -   || 16 > DL_STACK_ALIGNMENT)
> > +#include "dl-trampoline-save.h"
> >
> >  /* Area on stack to save and restore registers used for parameter
> >     passing when calling _dl_fixup.  */
> > diff --git a/sysdeps/x86_64/dl-trampoline.h b/sysdeps/x86_64/dl-trampoline.h
> > index f55c6ea040..d9ccfb40d4 100644
> > --- a/sysdeps/x86_64/dl-trampoline.h
> > +++ b/sysdeps/x86_64/dl-trampoline.h
> > @@ -27,39 +27,7 @@
> >  # undef LOCAL_STORAGE_AREA
> >  # undef BASE
> >
> > -# if (STATE_SAVE_ALIGNMENT % 16) != 0
> > -#  error STATE_SAVE_ALIGNMENT must be multiple of 16
> > -# endif
> > -
> > -# if (STATE_SAVE_OFFSET % STATE_SAVE_ALIGNMENT) != 0
> > -#  error STATE_SAVE_OFFSET must be multiple of STATE_SAVE_ALIGNMENT
> > -# endif
> > -
> > -# if DL_RUNTIME_RESOLVE_REALIGN_STACK
> > -/* Local stack area before jumping to function address: RBX.  */
> > -#  define LOCAL_STORAGE_AREA   8
> > -#  define BASE                 rbx
> > -#  ifdef USE_FXSAVE
> > -/* Use fxsave to save XMM registers.  */
> > -#   define REGISTER_SAVE_AREA  (512 + STATE_SAVE_OFFSET)
> > -#   if (REGISTER_SAVE_AREA % 16) != 0
> > -#    error REGISTER_SAVE_AREA must be multiple of 16
> > -#   endif
> > -#  endif
> > -# else
> > -#  ifndef USE_FXSAVE
> > -#   error USE_FXSAVE must be defined
> > -#  endif
> > -/* Use fxsave to save XMM registers.  */
> > -#  define REGISTER_SAVE_AREA   (512 + STATE_SAVE_OFFSET + 8)
> > -/* Local stack area before jumping to function address:  All saved
> > -   registers.  */
> > -#  define LOCAL_STORAGE_AREA   REGISTER_SAVE_AREA
> > -#  define BASE                 rsp
> > -#  if (REGISTER_SAVE_AREA % 16) != 8
> > -#   error REGISTER_SAVE_AREA must be odd multiple of 8
> > -#  endif
> > -# endif
> > +# include "dl-trampoline-state.h"
> >
> >         .globl _dl_runtime_resolve
> >         .hidden _dl_runtime_resolve
> > --
> > 2.43.0
> >
>
> LGTM.
> Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
>
> Please wait for adhemerval to give the clear as well.

I don't think waiting is the solution.   Adhemerval mentioned that
his patch doesn't address all issues on arm:

https://sourceware.org/pipermail/libc-alpha/2024-February/154710.html

I'd like to check in my patch ASIS.  It is up to the target maintainers
to decide what to do with this known target specific bug.
diff mbox series

Patch

diff --git a/elf/Makefile b/elf/Makefile
index 5d78b659ce..030db4d207 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -424,6 +424,7 @@  tests += \
   tst-glibc-hwcaps-prepend \
   tst-global1 \
   tst-global2 \
+  tst-gnu2-tls2 \
   tst-initfinilazyfail \
   tst-initorder \
   tst-initorder2 \
@@ -846,6 +847,9 @@  modules-names += \
   tst-filterobj-flt \
   tst-finilazyfailmod \
   tst-globalmod2 \
+  tst-gnu2-tls2mod0 \
+  tst-gnu2-tls2mod1 \
+  tst-gnu2-tls2mod2 \
   tst-initlazyfailmod \
   tst-initorder2a \
   tst-initorder2b \
@@ -3044,8 +3048,18 @@  $(objpfx)tst-tlsgap.out: \
   $(objpfx)tst-tlsgap-mod0.so \
   $(objpfx)tst-tlsgap-mod1.so \
   $(objpfx)tst-tlsgap-mod2.so
+
+$(objpfx)tst-gnu2-tls2: $(shared-thread-library)
+$(objpfx)tst-gnu2-tls2.out: \
+  $(objpfx)tst-gnu2-tls2mod0.so \
+  $(objpfx)tst-gnu2-tls2mod1.so \
+  $(objpfx)tst-gnu2-tls2mod2.so
+
 ifeq (yes,$(have-mtls-dialect-gnu2))
 CFLAGS-tst-tlsgap-mod0.c += -mtls-dialect=gnu2
 CFLAGS-tst-tlsgap-mod1.c += -mtls-dialect=gnu2
 CFLAGS-tst-tlsgap-mod2.c += -mtls-dialect=gnu2
+CFLAGS-tst-gnu2-tls2mod0.c += -mtls-dialect=gnu2
+CFLAGS-tst-gnu2-tls2mod1.c += -mtls-dialect=gnu2
+CFLAGS-tst-gnu2-tls2mod2.c += -mtls-dialect=gnu2
 endif
diff --git a/elf/tst-gnu2-tls2.c b/elf/tst-gnu2-tls2.c
new file mode 100644
index 0000000000..8039ba614d
--- /dev/null
+++ b/elf/tst-gnu2-tls2.c
@@ -0,0 +1,120 @@ 
+/* Test TLSDESC relocation.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <dlfcn.h>
+#include <pthread.h>
+#include <support/xdlfcn.h>
+#include <support/xthread.h>
+#include <support/check.h>
+#include <support/test-driver.h>
+#include "tst-gnu2-tls2.h"
+
+#ifndef IS_SUPPORTED
+# define IS_SUPPORTED() true
+#endif
+
+/* An architecture can define it to clobber caller-saved registers in
+   malloc below to verify that the implicit TLSDESC call won't change
+   caller-saved registers.  */
+#ifndef PREPARE_MALLOC
+# define PREPARE_MALLOC()
+#endif
+
+extern void * __libc_malloc (size_t);
+
+size_t malloc_counter = 0;
+
+void *
+malloc (size_t n)
+{
+  PREPARE_MALLOC ();
+  malloc_counter++;
+  return __libc_malloc (n);
+}
+
+static void *mod[3];
+#define MOD(i) "tst-gnu2-tls2mod" #i ".so"
+static const char *modname[3] = { MOD(0), MOD(1), MOD(2) };
+#undef MOD
+
+static void
+open_mod (int i)
+{
+  mod[i] = xdlopen (modname[i], RTLD_LAZY);
+  printf ("open %s\n", modname[i]);
+}
+
+static void
+close_mod (int i)
+{
+  xdlclose (mod[i]);
+  mod[i] = NULL;
+  printf ("close %s\n", modname[i]);
+}
+
+static void
+access_mod (int i, const char *sym)
+{
+  struct tls var = { -1, -1, -1, -1 };
+  struct tls *(*f) (struct tls *) = xdlsym (mod[i], sym);
+  /* Check that our malloc is called.  */
+  malloc_counter = 0;
+  struct tls *p = f (&var);
+  TEST_VERIFY (malloc_counter != 0);
+  printf ("access %s: %s() = %p\n", modname[i], sym, p);
+  TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
+  ++(p->a);
+}
+
+static void *
+start (void *arg)
+{
+  /* The DTV generation is at the last dlopen of mod0 and the
+     entry for mod1 is NULL.  */
+
+  open_mod (1); /* Reuse modid of mod1. Uses dynamic TLS.  */
+
+  /* Force the slow path in GNU2 TLS descriptor call.  */
+  access_mod (1, "apply_tls");
+
+  return arg;
+}
+
+static int
+do_test (void)
+{
+  if (!IS_SUPPORTED ())
+    return EXIT_UNSUPPORTED;
+
+  open_mod (0);
+  open_mod (1);
+  open_mod (2);
+  close_mod (0);
+  close_mod (1); /* Create modid gap at mod1.  */
+  open_mod (0); /* Reuse modid of mod0, bump generation count.  */
+
+  /* Create a thread where DTV of mod1 is NULL.  */
+  pthread_t t = xpthread_create (NULL, start, NULL);
+  xpthread_join (t);
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/elf/tst-gnu2-tls2.h b/elf/tst-gnu2-tls2.h
new file mode 100644
index 0000000000..77964a57a3
--- /dev/null
+++ b/elf/tst-gnu2-tls2.h
@@ -0,0 +1,36 @@ 
+/* Test TLSDESC relocation.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdint.h>
+
+struct tls
+{
+  int64_t a, b, c, d;
+};
+
+extern struct tls *apply_tls (struct tls *);
+
+/* An architecture can define them to verify that clobber caller-saved
+   registers aren't changed by the implicit TLSDESC call.  */
+#ifndef BEFORE_TLSDESC_CALL
+# define BEFORE_TLSDESC_CALL()
+#endif
+
+#ifndef AFTER_TLSDESC_CALL
+# define AFTER_TLSDESC_CALL()
+#endif
diff --git a/elf/tst-gnu2-tls2mod0.c b/elf/tst-gnu2-tls2mod0.c
new file mode 100644
index 0000000000..20f177244d
--- /dev/null
+++ b/elf/tst-gnu2-tls2mod0.c
@@ -0,0 +1,31 @@ 
+/* DSO used by tst-gnu2-tls2.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include "tst-gnu2-tls2.h"
+
+__thread struct tls tls_var0 __attribute__ ((visibility ("hidden")));
+
+struct tls *
+apply_tls (struct tls *p)
+{
+  tls_var0 = *p;
+  BEFORE_TLSDESC_CALL ();
+  struct tls *ret = &tls_var0;
+  AFTER_TLSDESC_CALL ();
+  return ret;
+}
diff --git a/elf/tst-gnu2-tls2mod1.c b/elf/tst-gnu2-tls2mod1.c
new file mode 100644
index 0000000000..86a6ee48f7
--- /dev/null
+++ b/elf/tst-gnu2-tls2mod1.c
@@ -0,0 +1,31 @@ 
+/* DSO used by tst-gnu2-tls2.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include "tst-gnu2-tls2.h"
+
+__thread struct tls tls_var1[100] __attribute__ ((visibility ("hidden")));
+
+struct tls *
+apply_tls (struct tls *p)
+{
+  tls_var1[1] = *p;
+  BEFORE_TLSDESC_CALL ();
+  struct tls *ret = &tls_var1[1];
+  AFTER_TLSDESC_CALL ();
+  return ret;
+}
diff --git a/elf/tst-gnu2-tls2mod2.c b/elf/tst-gnu2-tls2mod2.c
new file mode 100644
index 0000000000..dede07599b
--- /dev/null
+++ b/elf/tst-gnu2-tls2mod2.c
@@ -0,0 +1,31 @@ 
+/* DSO used by tst-gnu2-tls2.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include "tst-gnu2-tls2.h"
+
+__thread struct tls tls_var2 __attribute__ ((visibility ("hidden")));
+
+struct tls *
+apply_tls (struct tls *p)
+{
+  tls_var2 = *p;
+  BEFORE_TLSDESC_CALL ();
+  struct tls *ret = &tls_var2;
+  AFTER_TLSDESC_CALL ();
+  return ret;
+}
diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
index fc1ef96587..50d74fe6e9 100644
--- a/sysdeps/i386/dl-machine.h
+++ b/sysdeps/i386/dl-machine.h
@@ -347,7 +347,7 @@  and creates an unsatisfiable circular dependency.\n",
 		  {
 		    td->arg = _dl_make_tlsdesc_dynamic
 		      (sym_map, sym->st_value + (ElfW(Word))td->arg);
-		    td->entry = _dl_tlsdesc_dynamic;
+		    td->entry = GLRO(dl_x86_tlsdesc_dynamic);
 		  }
 		else
 #  endif
diff --git a/sysdeps/i386/dl-tlsdesc-dynamic.h b/sysdeps/i386/dl-tlsdesc-dynamic.h
new file mode 100644
index 0000000000..3627028577
--- /dev/null
+++ b/sysdeps/i386/dl-tlsdesc-dynamic.h
@@ -0,0 +1,190 @@ 
+/* Thread-local storage handling in the ELF dynamic linker.  i386 version.
+   Copyright (C) 2004-2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#undef REGISTER_SAVE_AREA
+
+#if !defined USE_FNSAVE && (STATE_SAVE_ALIGNMENT % 16) != 0
+# error STATE_SAVE_ALIGNMENT must be multiple of 16
+#endif
+
+#if DL_RUNTIME_RESOLVE_REALIGN_STACK
+# ifdef USE_FNSAVE
+#  error USE_FNSAVE shouldn't be defined
+# endif
+# ifdef USE_FXSAVE
+/* Use fxsave to save all registers.  */
+#  define REGISTER_SAVE_AREA	512
+# endif
+#else
+# ifdef USE_FNSAVE
+/* Use fnsave to save x87 FPU stack registers.  */
+#  define REGISTER_SAVE_AREA	108
+# else
+#  ifndef USE_FXSAVE
+#   error USE_FXSAVE must be defined
+#  endif
+/* Use fxsave to save all registers.  Add 12 bytes to align the stack
+   to 16 bytes.  */
+#  define REGISTER_SAVE_AREA	(512 + 12)
+# endif
+#endif
+
+	.hidden _dl_tlsdesc_dynamic
+	.global	_dl_tlsdesc_dynamic
+	.type	_dl_tlsdesc_dynamic,@function
+
+     /* This function is used for symbols that need dynamic TLS.
+
+	%eax points to the TLS descriptor, such that 0(%eax) points to
+	_dl_tlsdesc_dynamic itself, and 4(%eax) points to a struct
+	tlsdesc_dynamic_arg object.  It must return in %eax the offset
+	between the thread pointer and the object denoted by the
+	argument, without clobbering any registers.
+
+	The assembly code that follows is a rendition of the following
+	C code, hand-optimized a little bit.
+
+ptrdiff_t
+__attribute__ ((__regparm__ (1)))
+_dl_tlsdesc_dynamic (struct tlsdesc *tdp)
+{
+  struct tlsdesc_dynamic_arg *td = tdp->arg;
+  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
+  if (__builtin_expect (td->gen_count <= dtv[0].counter
+			&& (dtv[td->tlsinfo.ti_module].pointer.val
+			    != TLS_DTV_UNALLOCATED),
+			1))
+    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
+      - __thread_pointer;
+
+  return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
+}
+*/
+	cfi_startproc
+	.align 16
+_dl_tlsdesc_dynamic:
+	/* Like all TLS resolvers, preserve call-clobbered registers.
+	   We need two scratch regs anyway.  */
+	subl	$32, %esp
+	cfi_adjust_cfa_offset (32)
+	movl	%ecx, 20(%esp)
+	movl	%edx, 24(%esp)
+	movl	TLSDESC_ARG(%eax), %eax
+	movl	%gs:DTV_OFFSET, %edx
+	movl	TLSDESC_GEN_COUNT(%eax), %ecx
+	cmpl	(%edx), %ecx
+	ja	2f
+	movl	TLSDESC_MODID(%eax), %ecx
+	movl	(%edx,%ecx,8), %edx
+	cmpl	$-1, %edx
+	je	2f
+	movl	TLSDESC_MODOFF(%eax), %eax
+	addl	%edx, %eax
+1:
+	movl	20(%esp), %ecx
+	subl	%gs:0, %eax
+	movl	24(%esp), %edx
+	addl	$32, %esp
+	cfi_adjust_cfa_offset (-32)
+	ret
+	.p2align 4,,7
+2:
+	cfi_adjust_cfa_offset (32)
+#if DL_RUNTIME_RESOLVE_REALIGN_STACK
+	movl	%ebx, -28(%esp)
+	movl	%esp, %ebx
+	cfi_def_cfa_register(%ebx)
+	and	$-STATE_SAVE_ALIGNMENT, %esp
+#endif
+#ifdef REGISTER_SAVE_AREA
+	subl	$REGISTER_SAVE_AREA, %esp
+# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
+	cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
+# endif
+#else
+# if !DL_RUNTIME_RESOLVE_REALIGN_STACK
+#  error DL_RUNTIME_RESOLVE_REALIGN_STACK must be true
+# endif
+	/* Allocate stack space of the required size to save the state.  */
+	LOAD_PIC_REG (cx)
+	subl	RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_SIZE_OFFSET+_rtld_local_ro@GOTOFF(%ecx), %esp
+#endif
+#ifdef USE_FNSAVE
+	fnsave	(%esp)
+#elif defined USE_FXSAVE
+	fxsave	(%esp)
+#else
+	/* Save the argument for ___tls_get_addr in EAX.  */
+	movl	%eax, %ecx
+	movl	$TLSDESC_CALL_STATE_SAVE_MASK, %eax
+	xorl	%edx, %edx
+	/* Clear the XSAVE Header.  */
+# ifdef USE_XSAVE
+	movl	%edx, (512)(%esp)
+	movl	%edx, (512 + 4 * 1)(%esp)
+	movl	%edx, (512 + 4 * 2)(%esp)
+	movl	%edx, (512 + 4 * 3)(%esp)
+# endif
+	movl	%edx, (512 + 4 * 4)(%esp)
+	movl	%edx, (512 + 4 * 5)(%esp)
+	movl	%edx, (512 + 4 * 6)(%esp)
+	movl	%edx, (512 + 4 * 7)(%esp)
+	movl	%edx, (512 + 4 * 8)(%esp)
+	movl	%edx, (512 + 4 * 9)(%esp)
+	movl	%edx, (512 + 4 * 10)(%esp)
+	movl	%edx, (512 + 4 * 11)(%esp)
+	movl	%edx, (512 + 4 * 12)(%esp)
+	movl	%edx, (512 + 4 * 13)(%esp)
+	movl	%edx, (512 + 4 * 14)(%esp)
+	movl	%edx, (512 + 4 * 15)(%esp)
+# ifdef USE_XSAVE
+	xsave	(%esp)
+# else
+	xsavec	(%esp)
+# endif
+	/* Restore the argument for ___tls_get_addr in EAX.  */
+	movl	%ecx, %eax
+#endif
+	call	HIDDEN_JUMPTARGET (___tls_get_addr)
+	/* Get register content back.  */
+#ifdef USE_FNSAVE
+	frstor	(%esp)
+#elif defined USE_FXSAVE
+	fxrstor	(%esp)
+#else
+	/* Save and retore ___tls_get_addr return value stored in EAX.  */
+	movl	%eax, %ecx
+	movl	$TLSDESC_CALL_STATE_SAVE_MASK, %eax
+	xorl	%edx, %edx
+	xrstor	(%esp)
+	movl	%ecx, %eax
+#endif
+#if DL_RUNTIME_RESOLVE_REALIGN_STACK
+	mov	%ebx, %esp
+	cfi_def_cfa_register(%esp)
+	movl	-28(%esp), %ebx
+	cfi_restore(%ebx)
+#else
+	addl	$REGISTER_SAVE_AREA, %esp
+	cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
+#endif
+	jmp	1b
+	cfi_endproc
+	.size	_dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
+
+#undef STATE_SAVE_ALIGNMENT
diff --git a/sysdeps/i386/dl-tlsdesc.S b/sysdeps/i386/dl-tlsdesc.S
index 90d93caa0c..f002feee56 100644
--- a/sysdeps/i386/dl-tlsdesc.S
+++ b/sysdeps/i386/dl-tlsdesc.S
@@ -18,8 +18,27 @@ 
 
 #include <sysdep.h>
 #include <tls.h>
+#include <cpu-features-offsets.h>
+#include <features-offsets.h>
 #include "tlsdesc.h"
 
+#ifndef DL_STACK_ALIGNMENT
+/* Due to GCC bug:
+
+   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
+
+   __tls_get_addr may be called with 4-byte stack alignment.  Although
+   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
+   that stack will be always aligned at 16 bytes.  */
+# define DL_STACK_ALIGNMENT 4
+#endif
+
+/* True if _dl_tlsdesc_dynamic should align stack for STATE_SAVE or align
+   stack to MINIMUM_ALIGNMENT bytes before calling ___tls_get_addr.  */
+#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
+  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
+   || MINIMUM_ALIGNMENT > DL_STACK_ALIGNMENT)
+
 	.text
 
      /* This function is used to compute the TP offset for symbols in
@@ -65,69 +84,35 @@  _dl_tlsdesc_undefweak:
 	.size	_dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
 
 #ifdef SHARED
-	.hidden _dl_tlsdesc_dynamic
-	.global	_dl_tlsdesc_dynamic
-	.type	_dl_tlsdesc_dynamic,@function
-
-     /* This function is used for symbols that need dynamic TLS.
-
-	%eax points to the TLS descriptor, such that 0(%eax) points to
-	_dl_tlsdesc_dynamic itself, and 4(%eax) points to a struct
-	tlsdesc_dynamic_arg object.  It must return in %eax the offset
-	between the thread pointer and the object denoted by the
-	argument, without clobbering any registers.
-
-	The assembly code that follows is a rendition of the following
-	C code, hand-optimized a little bit.
-
-ptrdiff_t
-__attribute__ ((__regparm__ (1)))
-_dl_tlsdesc_dynamic (struct tlsdesc *tdp)
-{
-  struct tlsdesc_dynamic_arg *td = tdp->arg;
-  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
-  if (__builtin_expect (td->gen_count <= dtv[0].counter
-			&& (dtv[td->tlsinfo.ti_module].pointer.val
-			    != TLS_DTV_UNALLOCATED),
-			1))
-    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
-      - __thread_pointer;
-
-  return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
-}
-*/
-	cfi_startproc
-	.align 16
-_dl_tlsdesc_dynamic:
-	/* Like all TLS resolvers, preserve call-clobbered registers.
-	   We need two scratch regs anyway.  */
-	subl	$28, %esp
-	cfi_adjust_cfa_offset (28)
-	movl	%ecx, 20(%esp)
-	movl	%edx, 24(%esp)
-	movl	TLSDESC_ARG(%eax), %eax
-	movl	%gs:DTV_OFFSET, %edx
-	movl	TLSDESC_GEN_COUNT(%eax), %ecx
-	cmpl	(%edx), %ecx
-	ja	.Lslow
-	movl	TLSDESC_MODID(%eax), %ecx
-	movl	(%edx,%ecx,8), %edx
-	cmpl	$-1, %edx
-	je	.Lslow
-	movl	TLSDESC_MODOFF(%eax), %eax
-	addl	%edx, %eax
-.Lret:
-	movl	20(%esp), %ecx
-	subl	%gs:0, %eax
-	movl	24(%esp), %edx
-	addl	$28, %esp
-	cfi_adjust_cfa_offset (-28)
-	ret
-	.p2align 4,,7
-.Lslow:
-	cfi_adjust_cfa_offset (28)
-	call	HIDDEN_JUMPTARGET (___tls_get_addr)
-	jmp	.Lret
-	cfi_endproc
-	.size	_dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
+# define USE_FNSAVE
+# define MINIMUM_ALIGNMENT	4
+# define STATE_SAVE_ALIGNMENT	4
+# define _dl_tlsdesc_dynamic	_dl_tlsdesc_dynamic_fnsave
+# include "dl-tlsdesc-dynamic.h"
+# undef _dl_tlsdesc_dynamic
+# undef MINIMUM_ALIGNMENT
+# undef USE_FNSAVE
+
+# define MINIMUM_ALIGNMENT	16
+
+# define USE_FXSAVE
+# define STATE_SAVE_ALIGNMENT	16
+# define _dl_tlsdesc_dynamic	_dl_tlsdesc_dynamic_fxsave
+# include "dl-tlsdesc-dynamic.h"
+# undef _dl_tlsdesc_dynamic
+# undef USE_FXSAVE
+
+# define USE_XSAVE
+# define STATE_SAVE_ALIGNMENT	64
+# define _dl_tlsdesc_dynamic	_dl_tlsdesc_dynamic_xsave
+# include "dl-tlsdesc-dynamic.h"
+# undef _dl_tlsdesc_dynamic
+# undef USE_XSAVE
+
+# define USE_XSAVEC
+# define STATE_SAVE_ALIGNMENT	64
+# define _dl_tlsdesc_dynamic	_dl_tlsdesc_dynamic_xsavec
+# include "dl-tlsdesc-dynamic.h"
+# undef _dl_tlsdesc_dynamic
+# undef USE_XSAVEC
 #endif /* SHARED */
diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
index 73b29cc78c..5311b594af 100644
--- a/sysdeps/x86/Makefile
+++ b/sysdeps/x86/Makefile
@@ -1,5 +1,5 @@ 
 ifeq ($(subdir),csu)
-gen-as-const-headers += cpu-features-offsets.sym
+gen-as-const-headers += cpu-features-offsets.sym features-offsets.sym
 endif
 
 ifeq ($(subdir),elf)
@@ -86,6 +86,11 @@  endif
 tst-ifunc-isa-2-ENV = GLIBC_TUNABLES=glibc.cpu.hwcaps=-SSE4_2,-AVX,-AVX2,-AVX512F
 tst-ifunc-isa-2-static-ENV = $(tst-ifunc-isa-2-ENV)
 tst-hwcap-tunables-ARGS = -- $(host-test-program-cmd)
+
+CFLAGS-tst-gnu2-tls2.c += -msse
+CFLAGS-tst-gnu2-tls2mod0.c += -msse2 -mtune=haswell
+CFLAGS-tst-gnu2-tls2mod1.c += -msse2 -mtune=haswell
+CFLAGS-tst-gnu2-tls2mod2.c += -msse2 -mtune=haswell
 endif
 
 ifeq ($(subdir),math)
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index 25e6622a79..835113b42f 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -27,8 +27,13 @@ 
 extern void TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *)
   attribute_hidden;
 
-#if defined SHARED && defined __x86_64__
-# include <dl-plt-rewrite.h>
+#if defined SHARED
+extern void _dl_tlsdesc_dynamic_fxsave (void) attribute_hidden;
+extern void _dl_tlsdesc_dynamic_xsave (void) attribute_hidden;
+extern void _dl_tlsdesc_dynamic_xsavec (void) attribute_hidden;
+
+# ifdef __x86_64__
+#  include <dl-plt-rewrite.h>
 
 static void
 TUNABLE_CALLBACK (set_plt_rewrite) (tunable_val_t *valp)
@@ -47,6 +52,15 @@  TUNABLE_CALLBACK (set_plt_rewrite) (tunable_val_t *valp)
 		 : plt_rewrite_jmp);
     }
 }
+# else
+extern void _dl_tlsdesc_dynamic_fnsave (void) attribute_hidden;
+# endif
+#endif
+
+#ifdef __x86_64__
+extern void _dl_runtime_resolve_fxsave (void) attribute_hidden;
+extern void _dl_runtime_resolve_xsave (void) attribute_hidden;
+extern void _dl_runtime_resolve_xsavec (void) attribute_hidden;
 #endif
 
 #ifdef __LP64__
@@ -1130,6 +1144,44 @@  no_cpuid:
 	       TUNABLE_CALLBACK (set_x86_shstk));
 #endif
 
+  if (GLRO(dl_x86_cpu_features).xsave_state_size != 0)
+    {
+      if (CPU_FEATURE_USABLE_P (cpu_features, XSAVEC))
+	{
+#ifdef __x86_64__
+	  GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_xsavec;
+#endif
+#ifdef SHARED
+	  GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_xsavec;
+#endif
+	}
+      else
+	{
+#ifdef __x86_64__
+	  GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_xsave;
+#endif
+#ifdef SHARED
+	  GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_xsave;
+#endif
+	}
+    }
+  else
+    {
+#ifdef __x86_64__
+      GLRO(dl_x86_64_runtime_resolve) = _dl_runtime_resolve_fxsave;
+# ifdef SHARED
+      GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fxsave;
+# endif
+#else
+# ifdef SHARED
+      if (CPU_FEATURE_USABLE_P (cpu_features, FXSR))
+	GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fxsave;
+      else
+	GLRO(dl_x86_tlsdesc_dynamic) = _dl_tlsdesc_dynamic_fnsave;
+# endif
+#endif
+    }
+
 #ifdef SHARED
 # ifdef __x86_64__
   TUNABLE_GET (plt_rewrite, tunable_val_t *,
diff --git a/sysdeps/x86/dl-procinfo.c b/sysdeps/x86/dl-procinfo.c
index ee957b4d70..5920d4b320 100644
--- a/sysdeps/x86/dl-procinfo.c
+++ b/sysdeps/x86/dl-procinfo.c
@@ -86,3 +86,19 @@  PROCINFO_CLASS const char _dl_x86_platforms[4][9]
 #else
 ,
 #endif
+
+#if defined SHARED && !IS_IN (ldconfig)
+# if !defined PROCINFO_DECL
+  ._dl_x86_tlsdesc_dynamic
+# else
+PROCINFO_CLASS void * _dl_x86_tlsdesc_dynamic
+# endif
+# ifndef PROCINFO_DECL
+= NULL
+# endif
+# ifdef PROCINFO_DECL
+;
+# else
+,
+# endif
+#endif
diff --git a/sysdeps/x86_64/features-offsets.sym b/sysdeps/x86/features-offsets.sym
similarity index 89%
rename from sysdeps/x86_64/features-offsets.sym
rename to sysdeps/x86/features-offsets.sym
index 9e4be3393a..77e990c705 100644
--- a/sysdeps/x86_64/features-offsets.sym
+++ b/sysdeps/x86/features-offsets.sym
@@ -3,4 +3,6 @@ 
 #include <ldsodefs.h>
 
 RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET offsetof (struct rtld_global_ro, _dl_x86_cpu_features)
+#ifdef __x86_64__
 RTLD_GLOBAL_DL_X86_FEATURE_1_OFFSET offsetof (struct rtld_global, _dl_x86_feature_1)
+#endif
diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
index 837fd28734..485cad9c02 100644
--- a/sysdeps/x86/sysdep.h
+++ b/sysdeps/x86/sysdep.h
@@ -70,6 +70,12 @@ 
    | (1 << X86_XSTATE_ZMM_H_ID))
 #endif
 
+/* States which should be saved for TLSDESC_CALL and TLS_DESC_CALL.
+   Compiler assumes that all registers, including x87 FPU stack registers,
+   are unchanged after CALL, except for EFLAGS and RAX/EAX.  */
+#define TLSDESC_CALL_STATE_SAVE_MASK	\
+  (STATE_SAVE_MASK | (1 << X86_XSTATE_X87_ID))
+
 /* Constants for bits in __x86_string_control:  */
 
 /* Avoid short distance REP MOVSB.  */
diff --git a/sysdeps/x86/tst-gnu2-tls2.c b/sysdeps/x86/tst-gnu2-tls2.c
new file mode 100644
index 0000000000..de900a423b
--- /dev/null
+++ b/sysdeps/x86/tst-gnu2-tls2.c
@@ -0,0 +1,20 @@ 
+#ifndef __x86_64__
+#include <sys/platform/x86.h>
+
+#define IS_SUPPORTED() CPU_FEATURE_ACTIVE (SSE2)
+#endif
+
+/* Clear XMM0...XMM7  */
+#define PREPARE_MALLOC()				\
+{							\
+  asm volatile ("xorps %%xmm0, %%xmm0" : : : "xmm0" );	\
+  asm volatile ("xorps %%xmm1, %%xmm1" : : : "xmm1" );	\
+  asm volatile ("xorps %%xmm2, %%xmm2" : : : "xmm2" );	\
+  asm volatile ("xorps %%xmm3, %%xmm3" : : : "xmm3" );	\
+  asm volatile ("xorps %%xmm4, %%xmm4" : : : "xmm4" );	\
+  asm volatile ("xorps %%xmm5, %%xmm5" : : : "xmm5" );	\
+  asm volatile ("xorps %%xmm6, %%xmm6" : : : "xmm6" );	\
+  asm volatile ("xorps %%xmm7, %%xmm7" : : : "xmm7" );	\
+}
+
+#include <elf/tst-gnu2-tls2.c>
diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile
index 145f25e7f6..9337e95093 100644
--- a/sysdeps/x86_64/Makefile
+++ b/sysdeps/x86_64/Makefile
@@ -10,7 +10,7 @@  LDFLAGS-rtld += -Wl,-z,nomark-plt
 endif
 
 ifeq ($(subdir),csu)
-gen-as-const-headers += features-offsets.sym link-defines.sym
+gen-as-const-headers += link-defines.sym
 endif
 
 ifeq ($(subdir),gmon)
diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
index 6d605d0d32..ff5d45f7cb 100644
--- a/sysdeps/x86_64/dl-machine.h
+++ b/sysdeps/x86_64/dl-machine.h
@@ -71,9 +71,6 @@  elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
 			   int lazy, int profile)
 {
   Elf64_Addr *got;
-  extern void _dl_runtime_resolve_fxsave (ElfW(Word)) attribute_hidden;
-  extern void _dl_runtime_resolve_xsave (ElfW(Word)) attribute_hidden;
-  extern void _dl_runtime_resolve_xsavec (ElfW(Word)) attribute_hidden;
   extern void _dl_runtime_profile_sse (ElfW(Word)) attribute_hidden;
   extern void _dl_runtime_profile_avx (ElfW(Word)) attribute_hidden;
   extern void _dl_runtime_profile_avx512 (ElfW(Word)) attribute_hidden;
@@ -96,8 +93,6 @@  elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
       /* Identify this shared object.  */
       *(ElfW(Addr) *) (got + 1) = (ElfW(Addr)) l;
 
-      const struct cpu_features* cpu_features = __get_cpu_features ();
-
 #ifdef SHARED
       /* The got[2] entry contains the address of a function which gets
 	 called to get the address of a so far unresolved function and
@@ -107,6 +102,7 @@  elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
 	 end in this function.  */
       if (__glibc_unlikely (profile))
 	{
+	  const struct cpu_features* cpu_features = __get_cpu_features ();
 	  if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512F))
 	    *(ElfW(Addr) *) (got + 2) = (ElfW(Addr)) &_dl_runtime_profile_avx512;
 	  else if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX))
@@ -126,15 +122,8 @@  elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
 	  /* This function will get called to fix up the GOT entry
 	     indicated by the offset on the stack, and then jump to
 	     the resolved address.  */
-	  if (MINIMUM_X86_ISA_LEVEL >= AVX_X86_ISA_LEVEL
-	      || GLRO(dl_x86_cpu_features).xsave_state_size != 0)
-	    *(ElfW(Addr) *) (got + 2)
-	      = (CPU_FEATURE_USABLE_P (cpu_features, XSAVEC)
-		 ? (ElfW(Addr)) &_dl_runtime_resolve_xsavec
-		 : (ElfW(Addr)) &_dl_runtime_resolve_xsave);
-	  else
-	    *(ElfW(Addr) *) (got + 2)
-	      = (ElfW(Addr)) &_dl_runtime_resolve_fxsave;
+	  *(ElfW(Addr) *) (got + 2)
+	    = (ElfW(Addr)) GLRO(dl_x86_64_runtime_resolve);
 	}
     }
 
@@ -383,7 +372,7 @@  and creates an unsatisfiable circular dependency.\n",
 		  {
 		    td->arg = _dl_make_tlsdesc_dynamic
 		      (sym_map, sym->st_value + reloc->r_addend);
-		    td->entry = _dl_tlsdesc_dynamic;
+		    td->entry = GLRO(dl_x86_tlsdesc_dynamic);
 		  }
 		else
 #  endif
diff --git a/sysdeps/x86_64/dl-procinfo.c b/sysdeps/x86_64/dl-procinfo.c
index 4d1d790fbb..06637a8154 100644
--- a/sysdeps/x86_64/dl-procinfo.c
+++ b/sysdeps/x86_64/dl-procinfo.c
@@ -41,5 +41,21 @@ 
 
 #include <sysdeps/x86/dl-procinfo.c>
 
+#if !IS_IN (ldconfig)
+# if !defined PROCINFO_DECL && defined SHARED
+  ._dl_x86_64_runtime_resolve
+# else
+PROCINFO_CLASS void * _dl_x86_64_runtime_resolve
+# endif
+# ifndef PROCINFO_DECL
+= NULL
+# endif
+# if !defined SHARED || defined PROCINFO_DECL
+;
+# else
+,
+# endif
+#endif
+
 #undef PROCINFO_DECL
 #undef PROCINFO_CLASS
diff --git a/sysdeps/x86_64/dl-tlsdesc-dynamic.h b/sysdeps/x86_64/dl-tlsdesc-dynamic.h
new file mode 100644
index 0000000000..0c2e8d5320
--- /dev/null
+++ b/sysdeps/x86_64/dl-tlsdesc-dynamic.h
@@ -0,0 +1,166 @@ 
+/* Thread-local storage handling in the ELF dynamic linker.  x86_64 version.
+   Copyright (C) 2004-2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef SECTION
+# define SECTION(p)	p
+#endif
+
+#undef REGISTER_SAVE_AREA
+#undef LOCAL_STORAGE_AREA
+#undef BASE
+
+#include "dl-trampoline-state.h"
+
+	.section SECTION(.text),"ax",@progbits
+
+	.hidden _dl_tlsdesc_dynamic
+	.global	_dl_tlsdesc_dynamic
+	.type	_dl_tlsdesc_dynamic,@function
+
+     /* %rax points to the TLS descriptor, such that 0(%rax) points to
+	_dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct
+	tlsdesc_dynamic_arg object.  It must return in %rax the offset
+	between the thread pointer and the object denoted by the
+	argument, without clobbering any registers.
+
+	The assembly code that follows is a rendition of the following
+	C code, hand-optimized a little bit.
+
+ptrdiff_t
+_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax"))
+{
+  struct tlsdesc_dynamic_arg *td = tdp->arg;
+  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
+  if (__builtin_expect (td->gen_count <= dtv[0].counter
+			&& (dtv[td->tlsinfo.ti_module].pointer.val
+			    != TLS_DTV_UNALLOCATED),
+			1))
+    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
+      - __thread_pointer;
+
+  return __tls_get_addr_internal (&td->tlsinfo) - __thread_pointer;
+}
+*/
+	cfi_startproc
+	.align 16
+_dl_tlsdesc_dynamic:
+	_CET_ENDBR
+	/* Preserve call-clobbered registers that we modify.
+	   We need two scratch regs anyway.  */
+	movq	%rsi, -16(%rsp)
+	mov	%fs:DTV_OFFSET, %RSI_LP
+	movq	%rdi, -8(%rsp)
+	movq	TLSDESC_ARG(%rax), %rdi
+	movq	(%rsi), %rax
+	cmpq	%rax, TLSDESC_GEN_COUNT(%rdi)
+	ja	2f
+	movq	TLSDESC_MODID(%rdi), %rax
+	salq	$4, %rax
+	movq	(%rax,%rsi), %rax
+	cmpq	$-1, %rax
+	je	2f
+	addq	TLSDESC_MODOFF(%rdi), %rax
+1:
+	movq	-16(%rsp), %rsi
+	sub	%fs:0, %RAX_LP
+	movq	-8(%rsp), %rdi
+	ret
+2:
+#if DL_RUNTIME_RESOLVE_REALIGN_STACK
+	movq	%rbx, -24(%rsp)
+	mov	%RSP_LP, %RBX_LP
+	cfi_def_cfa_register(%rbx)
+	and	$-STATE_SAVE_ALIGNMENT, %RSP_LP
+#endif
+#ifdef REGISTER_SAVE_AREA
+# if DL_RUNTIME_RESOLVE_REALIGN_STACK
+	/* STATE_SAVE_OFFSET has space for 8 integer registers.  But we
+	   need space for RCX, RDX, RSI, RDI, R8, R9, R10 and R11, plus
+	   RBX above.  */
+	sub	$(REGISTER_SAVE_AREA + STATE_SAVE_ALIGNMENT), %RSP_LP
+# else
+	sub	$REGISTER_SAVE_AREA, %RSP_LP
+	cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
+# endif
+#else
+	/* Allocate stack space of the required size to save the state.  */
+	sub	_rtld_local_ro+RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET+XSAVE_STATE_SIZE_OFFSET(%rip), %RSP_LP
+#endif
+	/* Besides rdi and rsi, saved above, save rcx, rdx, r8, r9,
+	   r10 and r11.  */
+	movq	%rcx, REGISTER_SAVE_RCX(%rsp)
+	movq	%rdx, REGISTER_SAVE_RDX(%rsp)
+	movq	%r8, REGISTER_SAVE_R8(%rsp)
+	movq	%r9, REGISTER_SAVE_R9(%rsp)
+	movq	%r10, REGISTER_SAVE_R10(%rsp)
+	movq	%r11, REGISTER_SAVE_R11(%rsp)
+#ifdef USE_FXSAVE
+	fxsave	STATE_SAVE_OFFSET(%rsp)
+#else
+	movl	$TLSDESC_CALL_STATE_SAVE_MASK, %eax
+	xorl	%edx, %edx
+	/* Clear the XSAVE Header.  */
+# ifdef USE_XSAVE
+	movq	%rdx, (STATE_SAVE_OFFSET + 512)(%rsp)
+	movq	%rdx, (STATE_SAVE_OFFSET + 512 + 8)(%rsp)
+# endif
+	movq	%rdx, (STATE_SAVE_OFFSET + 512 + 8 * 2)(%rsp)
+	movq	%rdx, (STATE_SAVE_OFFSET + 512 + 8 * 3)(%rsp)
+	movq	%rdx, (STATE_SAVE_OFFSET + 512 + 8 * 4)(%rsp)
+	movq	%rdx, (STATE_SAVE_OFFSET + 512 + 8 * 5)(%rsp)
+	movq	%rdx, (STATE_SAVE_OFFSET + 512 + 8 * 6)(%rsp)
+	movq	%rdx, (STATE_SAVE_OFFSET + 512 + 8 * 7)(%rsp)
+# ifdef USE_XSAVE
+	xsave	STATE_SAVE_OFFSET(%rsp)
+# else
+	xsavec	STATE_SAVE_OFFSET(%rsp)
+# endif
+#endif
+	/* %rdi already points to the tlsinfo data structure.  */
+	call	HIDDEN_JUMPTARGET (__tls_get_addr)
+	# Get register content back.
+#ifdef USE_FXSAVE
+	fxrstor	STATE_SAVE_OFFSET(%rsp)
+#else
+	/* Save and retore __tls_get_addr return value stored in RAX.  */
+	mov	%RAX_LP, %RCX_LP
+	movl	$TLSDESC_CALL_STATE_SAVE_MASK, %eax
+	xorl	%edx, %edx
+	xrstor	STATE_SAVE_OFFSET(%rsp)
+	mov	%RCX_LP, %RAX_LP
+#endif
+	movq	REGISTER_SAVE_R11(%rsp), %r11
+	movq	REGISTER_SAVE_R10(%rsp), %r10
+	movq	REGISTER_SAVE_R9(%rsp), %r9
+	movq	REGISTER_SAVE_R8(%rsp), %r8
+	movq	REGISTER_SAVE_RDX(%rsp), %rdx
+	movq	REGISTER_SAVE_RCX(%rsp), %rcx
+#if DL_RUNTIME_RESOLVE_REALIGN_STACK
+	mov	%RBX_LP, %RSP_LP
+	cfi_def_cfa_register(%rsp)
+	movq	-24(%rsp), %rbx
+	cfi_restore(%rbx)
+#else
+	add	$REGISTER_SAVE_AREA, %RSP_LP
+	cfi_adjust_cfa_offset(-REGISTER_SAVE_AREA)
+#endif
+	jmp	1b
+	cfi_endproc
+	.size	_dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
+
+#undef STATE_SAVE_ALIGNMENT
diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S
index f748af2ece..ea69f5223a 100644
--- a/sysdeps/x86_64/dl-tlsdesc.S
+++ b/sysdeps/x86_64/dl-tlsdesc.S
@@ -18,7 +18,19 @@ 
 
 #include <sysdep.h>
 #include <tls.h>
+#include <cpu-features-offsets.h>
+#include <features-offsets.h>
 #include "tlsdesc.h"
+#include "dl-trampoline-save.h"
+
+/* Area on stack to save and restore registers used for parameter
+   passing when calling _dl_tlsdesc_dynamic.  */
+#define REGISTER_SAVE_RCX	0
+#define REGISTER_SAVE_RDX	(REGISTER_SAVE_RCX + 8)
+#define REGISTER_SAVE_R8	(REGISTER_SAVE_RDX + 8)
+#define REGISTER_SAVE_R9	(REGISTER_SAVE_R8 + 8)
+#define REGISTER_SAVE_R10	(REGISTER_SAVE_R9 + 8)
+#define REGISTER_SAVE_R11	(REGISTER_SAVE_R10 + 8)
 
 	.text
 
@@ -67,80 +79,24 @@  _dl_tlsdesc_undefweak:
 	.size	_dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
 
 #ifdef SHARED
-	.hidden _dl_tlsdesc_dynamic
-	.global	_dl_tlsdesc_dynamic
-	.type	_dl_tlsdesc_dynamic,@function
-
-     /* %rax points to the TLS descriptor, such that 0(%rax) points to
-	_dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct
-	tlsdesc_dynamic_arg object.  It must return in %rax the offset
-	between the thread pointer and the object denoted by the
-	argument, without clobbering any registers.
-
-	The assembly code that follows is a rendition of the following
-	C code, hand-optimized a little bit.
-
-ptrdiff_t
-_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax"))
-{
-  struct tlsdesc_dynamic_arg *td = tdp->arg;
-  dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
-  if (__builtin_expect (td->gen_count <= dtv[0].counter
-			&& (dtv[td->tlsinfo.ti_module].pointer.val
-			    != TLS_DTV_UNALLOCATED),
-			1))
-    return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
-      - __thread_pointer;
-
-  return __tls_get_addr_internal (&td->tlsinfo) - __thread_pointer;
-}
-*/
-	cfi_startproc
-	.align 16
-_dl_tlsdesc_dynamic:
-	_CET_ENDBR
-	/* Preserve call-clobbered registers that we modify.
-	   We need two scratch regs anyway.  */
-	movq	%rsi, -16(%rsp)
-	mov	%fs:DTV_OFFSET, %RSI_LP
-	movq	%rdi, -8(%rsp)
-	movq	TLSDESC_ARG(%rax), %rdi
-	movq	(%rsi), %rax
-	cmpq	%rax, TLSDESC_GEN_COUNT(%rdi)
-	ja	.Lslow
-	movq	TLSDESC_MODID(%rdi), %rax
-	salq	$4, %rax
-	movq	(%rax,%rsi), %rax
-	cmpq	$-1, %rax
-	je	.Lslow
-	addq	TLSDESC_MODOFF(%rdi), %rax
-.Lret:
-	movq	-16(%rsp), %rsi
-	sub	%fs:0, %RAX_LP
-	movq	-8(%rsp), %rdi
-	ret
-.Lslow:
-	/* Besides rdi and rsi, saved above, save rdx, rcx, r8, r9,
-	   r10 and r11.  Also, align the stack, that's off by 8 bytes.	*/
-	subq	$72, %rsp
-	cfi_adjust_cfa_offset (72)
-	movq	%rdx, 8(%rsp)
-	movq	%rcx, 16(%rsp)
-	movq	%r8, 24(%rsp)
-	movq	%r9, 32(%rsp)
-	movq	%r10, 40(%rsp)
-	movq	%r11, 48(%rsp)
-	/* %rdi already points to the tlsinfo data structure.  */
-	call	HIDDEN_JUMPTARGET (__tls_get_addr)
-	movq	8(%rsp), %rdx
-	movq	16(%rsp), %rcx
-	movq	24(%rsp), %r8
-	movq	32(%rsp), %r9
-	movq	40(%rsp), %r10
-	movq	48(%rsp), %r11
-	addq	$72, %rsp
-	cfi_adjust_cfa_offset (-72)
-	jmp	.Lret
-	cfi_endproc
-	.size	_dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
+# define USE_FXSAVE
+# define STATE_SAVE_ALIGNMENT	16
+# define _dl_tlsdesc_dynamic	_dl_tlsdesc_dynamic_fxsave
+# include "dl-tlsdesc-dynamic.h"
+# undef _dl_tlsdesc_dynamic
+# undef USE_FXSAVE
+
+# define USE_XSAVE
+# define STATE_SAVE_ALIGNMENT	64
+# define _dl_tlsdesc_dynamic	_dl_tlsdesc_dynamic_xsave
+# include "dl-tlsdesc-dynamic.h"
+# undef _dl_tlsdesc_dynamic
+# undef USE_XSAVE
+
+# define USE_XSAVEC
+# define STATE_SAVE_ALIGNMENT	64
+# define _dl_tlsdesc_dynamic	_dl_tlsdesc_dynamic_xsavec
+# include "dl-tlsdesc-dynamic.h"
+# undef _dl_tlsdesc_dynamic
+# undef USE_XSAVEC
 #endif /* SHARED */
diff --git a/sysdeps/x86_64/dl-trampoline-save.h b/sysdeps/x86_64/dl-trampoline-save.h
new file mode 100644
index 0000000000..84eac4a8ac
--- /dev/null
+++ b/sysdeps/x86_64/dl-trampoline-save.h
@@ -0,0 +1,34 @@ 
+/* x86-64 PLT trampoline register save macros.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef DL_STACK_ALIGNMENT
+/* Due to GCC bug:
+
+   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
+
+   __tls_get_addr may be called with 8-byte stack alignment.  Although
+   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
+   that stack will be always aligned at 16 bytes.  */
+# define DL_STACK_ALIGNMENT 8
+#endif
+
+/* True if _dl_runtime_resolve should align stack for STATE_SAVE or align
+   stack to 16 bytes before calling _dl_fixup.  */
+#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
+  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
+   || 16 > DL_STACK_ALIGNMENT)
diff --git a/sysdeps/x86_64/dl-trampoline-state.h b/sysdeps/x86_64/dl-trampoline-state.h
new file mode 100644
index 0000000000..575f120797
--- /dev/null
+++ b/sysdeps/x86_64/dl-trampoline-state.h
@@ -0,0 +1,51 @@ 
+/* x86-64 PLT dl-trampoline state macros.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#if (STATE_SAVE_ALIGNMENT % 16) != 0
+# error STATE_SAVE_ALIGNMENT must be multiple of 16
+#endif
+
+#if (STATE_SAVE_OFFSET % STATE_SAVE_ALIGNMENT) != 0
+# error STATE_SAVE_OFFSET must be multiple of STATE_SAVE_ALIGNMENT
+#endif
+
+#if DL_RUNTIME_RESOLVE_REALIGN_STACK
+/* Local stack area before jumping to function address: RBX.  */
+# define LOCAL_STORAGE_AREA	8
+# define BASE			rbx
+# ifdef USE_FXSAVE
+/* Use fxsave to save XMM registers.  */
+#  define REGISTER_SAVE_AREA	(512 + STATE_SAVE_OFFSET)
+#  if (REGISTER_SAVE_AREA % 16) != 0
+#   error REGISTER_SAVE_AREA must be multiple of 16
+#  endif
+# endif
+#else
+# ifndef USE_FXSAVE
+#  error USE_FXSAVE must be defined
+# endif
+/* Use fxsave to save XMM registers.  */
+# define REGISTER_SAVE_AREA	(512 + STATE_SAVE_OFFSET + 8)
+/* Local stack area before jumping to function address:  All saved
+   registers.  */
+# define LOCAL_STORAGE_AREA	REGISTER_SAVE_AREA
+# define BASE			rsp
+# if (REGISTER_SAVE_AREA % 16) != 8
+#  error REGISTER_SAVE_AREA must be odd multiple of 8
+# endif
+#endif
diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S
index b2e7e0f69b..87c5137837 100644
--- a/sysdeps/x86_64/dl-trampoline.S
+++ b/sysdeps/x86_64/dl-trampoline.S
@@ -22,25 +22,7 @@ 
 #include <features-offsets.h>
 #include <link-defines.h>
 #include <isa-level.h>
-
-#ifndef DL_STACK_ALIGNMENT
-/* Due to GCC bug:
-
-   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
-
-   __tls_get_addr may be called with 8-byte stack alignment.  Although
-   this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
-   that stack will be always aligned at 16 bytes.  We use unaligned
-   16-byte move to load and store SSE registers, which has no penalty
-   on modern processors if stack is 16-byte aligned.  */
-# define DL_STACK_ALIGNMENT 8
-#endif
-
-/* True if _dl_runtime_resolve should align stack for STATE_SAVE or align
-   stack to 16 bytes before calling _dl_fixup.  */
-#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
-  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
-   || 16 > DL_STACK_ALIGNMENT)
+#include "dl-trampoline-save.h"
 
 /* Area on stack to save and restore registers used for parameter
    passing when calling _dl_fixup.  */
diff --git a/sysdeps/x86_64/dl-trampoline.h b/sysdeps/x86_64/dl-trampoline.h
index f55c6ea040..d9ccfb40d4 100644
--- a/sysdeps/x86_64/dl-trampoline.h
+++ b/sysdeps/x86_64/dl-trampoline.h
@@ -27,39 +27,7 @@ 
 # undef LOCAL_STORAGE_AREA
 # undef BASE
 
-# if (STATE_SAVE_ALIGNMENT % 16) != 0
-#  error STATE_SAVE_ALIGNMENT must be multiple of 16
-# endif
-
-# if (STATE_SAVE_OFFSET % STATE_SAVE_ALIGNMENT) != 0
-#  error STATE_SAVE_OFFSET must be multiple of STATE_SAVE_ALIGNMENT
-# endif
-
-# if DL_RUNTIME_RESOLVE_REALIGN_STACK
-/* Local stack area before jumping to function address: RBX.  */
-#  define LOCAL_STORAGE_AREA	8
-#  define BASE			rbx
-#  ifdef USE_FXSAVE
-/* Use fxsave to save XMM registers.  */
-#   define REGISTER_SAVE_AREA	(512 + STATE_SAVE_OFFSET)
-#   if (REGISTER_SAVE_AREA % 16) != 0
-#    error REGISTER_SAVE_AREA must be multiple of 16
-#   endif
-#  endif
-# else
-#  ifndef USE_FXSAVE
-#   error USE_FXSAVE must be defined
-#  endif
-/* Use fxsave to save XMM registers.  */
-#  define REGISTER_SAVE_AREA	(512 + STATE_SAVE_OFFSET + 8)
-/* Local stack area before jumping to function address:  All saved
-   registers.  */
-#  define LOCAL_STORAGE_AREA	REGISTER_SAVE_AREA
-#  define BASE			rsp
-#  if (REGISTER_SAVE_AREA % 16) != 8
-#   error REGISTER_SAVE_AREA must be odd multiple of 8
-#  endif
-# endif
+# include "dl-trampoline-state.h"
 
 	.globl _dl_runtime_resolve
 	.hidden _dl_runtime_resolve