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+/* Determine whether TLS is initialized, for AArch64/Hurd.
+ Copyright (C) 1995-2024 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/>. */
+
+/* Nothing here, it's all handled in tls.h */
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+/* Copyright (C) 2005-2024 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 _AARCH64_TLS_H
+#define _AARCH64_TLS_H 1
+
+/* Some things really need not be machine-dependent. */
+#include <sysdeps/mach/hurd/tls.h>
+
+#include <dl-sysdep.h>
+
+#ifndef __ASSEMBLER__
+# include <assert.h>
+# include <stdbool.h>
+# include <stddef.h>
+# include <stdint.h>
+# include <dl-dtv.h>
+# include <errno.h>
+# include <thread_state.h>
+#endif /* __ASSEMBLER__ */
+
+#ifndef __ASSEMBLER__
+
+/* Get system call information. */
+# include <sysdep.h>
+
+/* The TP points to the start of the thread blocks. */
+# define TLS_DTV_AT_TP 1
+# define TLS_TCB_AT_TP 0
+
+typedef struct
+{
+ /* Used by the exception handling implementation in the dynamic loader. */
+ struct rtld_catch *rtld_catch;
+
+ struct hurd_sigstate *_hurd_sigstate;
+ mach_port_t reply_port; /* This thread's reply port. */
+
+ int gscope_flag;
+} tcbprehead_t;
+
+typedef struct
+{
+ dtv_t *dtv;
+ void *private;
+} tcbhead_t;
+
+/* This is the size of the initial TCB. */
+# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
+
+/* This is the size we need before TCB. */
+# define TLS_PRE_TCB_SIZE sizeof (tcbprehead_t)
+
+# define TCB_ALIGNMENT 64
+
+/* Install new dtv for current thread. */
+# define INSTALL_NEW_DTV(dtv) \
+ (THREAD_DTV() = (dtv))
+
+/* Return the address of the dtv for the current thread. */
+# define THREAD_DTV() \
+ (((tcbhead_t *) __builtin_thread_pointer ())->dtv)
+
+/* Return the thread descriptor for the current thread. */
+# define THREAD_SELF \
+ ((tcbprehead_t *)__builtin_thread_pointer () - 1)
+
+/* Read member of the thread descriptor directly. */
+# define THREAD_GETMEM(descr, member) \
+ ((descr)->member)
+
+/* Write member of the thread descriptor directly. */
+# define THREAD_SETMEM(descr, member, value) \
+ ((descr)->member = (value))
+
+/* Return the TCB address of a thread given its state.
+ Note: this is expensive. */
+static inline tcbprehead_t * __attribute__ ((unused))
+THREAD_TCB (thread_t thread,
+ struct machine_thread_all_state *all_state)
+{
+ int ok;
+ const struct aarch64_thread_state *state;
+ tcbhead_t *tcb;
+
+ ok = machine_get_basic_state (thread, all_state);
+ assert (ok);
+ state = &((struct machine_thread_all_state *) all_state)->basic;
+ tcb = (tcbhead_t *) state->tpidr_el0;
+ return (tcbprehead_t *) tcb - 1;
+}
+
+/* From hurd.h, reproduced here to avoid a circular include. */
+extern thread_t __hurd_thread_self (void);
+libc_hidden_proto (__hurd_thread_self);
+
+/* Set up TLS in the new thread of a fork child, copying from the original. */
+static inline kern_return_t __attribute__ ((unused))
+_hurd_tls_fork (thread_t child, thread_t orig,
+ struct aarch64_thread_state *state)
+{
+ error_t err;
+ struct aarch64_thread_state orig_state;
+ mach_msg_type_number_t state_count = AARCH64_THREAD_STATE_COUNT;
+
+ if (orig != __hurd_thread_self ())
+ {
+ err = __thread_get_state (orig, AARCH64_THREAD_STATE,
+ (thread_state_t) &orig_state,
+ &state_count);
+ if (err)
+ return err;
+ assert (state_count == AARCH64_THREAD_STATE_COUNT);
+ state->tpidr_el0 = orig_state.tpidr_el0;
+ }
+ else
+ state->tpidr_el0 = (uintptr_t) __builtin_thread_pointer ();
+ return 0;
+}
+
+static inline kern_return_t __attribute__ ((unused))
+_hurd_tls_new (thread_t child, tcbhead_t *tcb)
+{
+ error_t err;
+ struct aarch64_thread_state state;
+ mach_msg_type_number_t state_count = AARCH64_THREAD_STATE_COUNT;
+
+ err = __thread_get_state (child, AARCH64_THREAD_STATE,
+ (thread_state_t) &state,
+ &state_count);
+ if (err)
+ return err;
+ assert (state_count == AARCH64_THREAD_STATE_COUNT);
+
+ state.tpidr_el0 = (uintptr_t) tcb;
+
+ return __thread_set_state (child, AARCH64_THREAD_STATE,
+ (thread_state_t) &state,
+ state_count);
+}
+
+# if !defined (SHARED) || IS_IN (rtld)
+# define __LIBC_NO_TLS() __builtin_expect (!__builtin_thread_pointer (), 0)
+
+static inline bool __attribute__ ((unused))
+_hurd_tls_init (tcbhead_t *tcb, bool full)
+{
+ extern mach_port_t __hurd_reply_port0;
+
+ if (full)
+ /* Take over the reply port we've been using. */
+ (((tcbprehead_t *) tcb) - 1)->reply_port = __hurd_reply_port0;
+
+ __asm __volatile ("msr tpidr_el0, %0" : : "r" (tcb));
+ if (full)
+ /* This port is now owned by the TCB. */
+ __hurd_reply_port0 = MACH_PORT_NULL;
+ return true;
+}
+
+# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr), 1)
+# else /* defined (SHARED) && !IS_IN (rtld) */
+# define __LIBC_NO_TLS() 0
+# endif
+
+/* Global scope switch support. */
+# define THREAD_GSCOPE_FLAG_UNUSED 0
+# define THREAD_GSCOPE_FLAG_USED 1
+# define THREAD_GSCOPE_FLAG_WAIT 2
+
+# define THREAD_GSCOPE_SET_FLAG() \
+ do \
+ { \
+ THREAD_SELF->gscope_flag = THREAD_GSCOPE_FLAG_USED; \
+ atomic_write_barrier (); \
+ } \
+ while (0)
+
+# define THREAD_GSCOPE_RESET_FLAG() \
+ do \
+ { int __flag \
+ = atomic_exchange_release (&THREAD_SELF->gscope_flag, \
+ THREAD_GSCOPE_FLAG_UNUSED); \
+ if (__flag == THREAD_GSCOPE_FLAG_WAIT) \
+ lll_wake (THREAD_SELF->gscope_flag, LLL_PRIVATE); \
+ } \
+ while (0)
+
+# endif /* __ASSEMBLER__ */
+
+#endif /* tls.h */
This is using TLS_DTV_AT_TP, aka "Variant I" layout. tpidr_el0, which is both readable and writable from userspace, is used as the thread pointer. We store our Hurd-specific data (sigstate and reply port) *before* the TCB head, in a tcbprehead_t structure. This tcbprehead_t structure is also what THREAD_SELF, THREAD_GETMEM, and THREAD_SETMEM macros access. Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> --- .../mach/hurd/aarch64/dl-tls-initialized.c | 19 ++ sysdeps/mach/hurd/aarch64/tls.h | 206 ++++++++++++++++++ 2 files changed, 225 insertions(+) create mode 100644 sysdeps/mach/hurd/aarch64/dl-tls-initialized.c create mode 100644 sysdeps/mach/hurd/aarch64/tls.h