[roland/arm] ARM: Consolidate with generic unwinder wrapper code
diff mbox

Message ID 20141218000551.EF87B2C3ABF@topped-with-meat.com
State New
Headers show

Commit Message

Roland McGrath Dec. 18, 2014, 12:05 a.m. UTC
This cleans up the ARM-specific unwinder wrappers to accomplish these things:

1. Move out of sysdeps/unix/sysv/linux/arm/ code that is not actually
   Linux-specific.
2. Eliminate duplication of the wrapper code between ARM-specific and
   generic code, with attendant skew.  To wit, this makes the ARM code
   use pointer mangling for the stored function pointers, as the generic
   code already does.  (The other difference is using LIBGCC_S_SO rather
   than hard-coded strings.)
3. Don't duplicate the ARM assembly code in two source files.
4. Move ARM assembly code from asm(...) into .S files, where it can take
   advantage of all our handy assembly macros.  In particular, being able
   to use PTR_DEMANGLE makes the pointer mangling support tractable, and
   being able to use LDR_HIDDEN is both an optimization from what was there
   before and makes this assembly code compatible with ARM_NO_INDEX_REGISTER
   configurations without any extra work.

While I was there, I also took the opportunity to rewrite the assembly stub
altogether.  Now it avoids frame setup for the fast path.

Verified no significant changes in generated code on x86_64-linux-gnu.
Tested no 'make check' regressions on armv7-linux-gnueabihf.

OK?


Thanks,
Roland


2014-12-17  Roland McGrath  <roland@hack.frob.com>

	* sysdeps/generic/unwind-resume.h: New file.
	* sysdeps/gnu/unwind-resume.c: Include it.
	(libgcc_s_personality): Use PERSONALITY_PROTO macro for the prototype.
	(__gcc_personality_v0): Likewise, and PERSONALITY_ARGS for the callee
	argument list.
	(libgcc_s_resume): Variable renamed to __libgcc_s_resume, made hidden
	global rather than static.
	(_Unwind_Resume): Update user.
	Conditionalize definition on [!HAVE_ARCH_UNWIND_RESUME].
	(init): Likewise.  Renamed to __libgcc_s_init, made hidden global
	rather than static.  Add __attribute__ ((cold)).
	(_Unwind_Resume, __gcc_personality_v0): Update callers.
	* sysdeps/nptl/unwind-forcedunwind.c: Likewise.
	* sysdeps/arm/arm-unwind-resume.S: New file.
	* sysdeps/arm/rt-arm-unwind-resume.S: New file.
	* sysdeps/arm/pt-arm-unwind-resume.S: New file.
	* sysdeps/arm/Makefile [$(subdir) = csu]
	(sysdep_routines, shared-only-routines): Add arm-unwind-resume.
	[$(subdir) = rt] (librt-sysdep_routines, librt-shared-only-routines):
	Add rt-arm-unwind-resume.
	[$(subdir) = nptl]
	(libpthread-sysdep_routines, libpthread-shared-only-routines):
	Add pt-arm-unwind-resume.
	* sysdeps/unix/sysv/linux/arm/unwind-resume.c: File removed.
	* sysdeps/unix/sysv/linux/arm/unwind-forcedunwind.c: File removed.

Comments

Joseph Myers Dec. 18, 2014, 6:12 p.m. UTC | #1
On Wed, 17 Dec 2014, Roland McGrath wrote:

> This cleans up the ARM-specific unwinder wrappers to accomplish these things:
> 
> 1. Move out of sysdeps/unix/sysv/linux/arm/ code that is not actually
>    Linux-specific.
> 2. Eliminate duplication of the wrapper code between ARM-specific and
>    generic code, with attendant skew.  To wit, this makes the ARM code
>    use pointer mangling for the stored function pointers, as the generic
>    code already does.  (The other difference is using LIBGCC_S_SO rather
>    than hard-coded strings.)
> 3. Don't duplicate the ARM assembly code in two source files.
> 4. Move ARM assembly code from asm(...) into .S files, where it can take
>    advantage of all our handy assembly macros.  In particular, being able
>    to use PTR_DEMANGLE makes the pointer mangling support tractable, and
>    being able to use LDR_HIDDEN is both an optimization from what was there
>    before and makes this assembly code compatible with ARM_NO_INDEX_REGISTER
>    configurations without any extra work.
> 
> While I was there, I also took the opportunity to rewrite the assembly stub
> altogether.  Now it avoids frame setup for the fast path.
> 
> Verified no significant changes in generated code on x86_64-linux-gnu.
> Tested no 'make check' regressions on armv7-linux-gnueabihf.
> 
> OK?

OK with a comment fixed as noted.

> +ENTRY (_Unwind_Resume)
> +	LDR_HIDDEN (ip, ip, __libgcc_s_resume, 0)
> +	cmp	ip, #0
> +	beq	1f
> +0:	PTR_DEMANGLE (ip, ip, r2, r3)
> +	bx	ip
> +
> +	/* We only really need to save and restore LR, but
> +	   the ABI requires the stack be kept aligned to 8 bytes,
> +	   so we push and pop r0 as well just to even out the stack.  */

r0 *does* need to be saved and restored, because it contains the argument 
being passed to _Unwind_Resume, and so needs to be preserved across the 
call to __libgcc_s_init which could clobber it.
Roland McGrath Jan. 5, 2015, 11:43 p.m. UTC | #2
Committed with changed comment.

Thanks,
Roland

Patch
diff mbox

--- a/sysdeps/arm/Makefile
+++ b/sysdeps/arm/Makefile
@@ -50,6 +50,9 @@  shared-only-routines += libc-aeabi_read_tp
 # cantunwind marker.  There's one in start.S.  To make sure we reach it, add
 # unwind tables for __libc_start_main.
 CFLAGS-libc-start.c += -fexceptions
+
+sysdep_routines += arm-unwind-resume
+shared-only-routines += arm-unwind-resume
 endif
 
 ifeq ($(subdir),gmon)
@@ -61,6 +64,11 @@  CFLAGS-backtrace.c += -funwind-tables
 endif
 
 ifeq ($(subdir),rt)
-librt-sysdep_routines += rt-aeabi_unwind_cpp_pr1
-librt-shared-only-routines += rt-aeabi_unwind_cpp_pr1
+librt-sysdep_routines += rt-aeabi_unwind_cpp_pr1 rt-arm-unwind-resume
+librt-shared-only-routines += rt-aeabi_unwind_cpp_pr1 rt-arm-unwind-resume
+endif
+
+ifeq ($(subdir),nptl)
+libpthread-sysdep_routines += pt-arm-unwind-resume
+libpthread-shared-only-routines += pt-arm-unwind-resume
 endif
--- /dev/null
+++ b/sysdeps/arm/arm-unwind-resume.S
@@ -0,0 +1,47 @@ 
+/* _Unwind_Resume wrapper for ARM EABI.
+   Copyright (C) 2014 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 <sysdep.h>
+
+/* This is just implementing exactly what the C version does.
+   We do it in assembly just to ensure that we get an unmolested tail
+   call to the libgcc function, which is necessary for the ARM unwinder.  */
+
+ENTRY (_Unwind_Resume)
+	LDR_HIDDEN (ip, ip, __libgcc_s_resume, 0)
+	cmp	ip, #0
+	beq	1f
+0:	PTR_DEMANGLE (ip, ip, r2, r3)
+	bx	ip
+
+	/* We only really need to save and restore LR, but
+	   the ABI requires the stack be kept aligned to 8 bytes,
+	   so we push and pop r0 as well just to even out the stack.  */
+1:	push	{r0, lr}
+	cfi_adjust_cfa_offset (8)
+	cfi_rel_offset (r0, 0)
+	cfi_rel_offset (lr, 4)
+	bl	__libgcc_s_init
+	pop	{r0, lr}
+	cfi_adjust_cfa_offset (-8)
+	cfi_restore (r0)
+	cfi_restore (lr)
+
+	LDR_HIDDEN (ip, ip, __libgcc_s_resume, 0)
+	b	0b
+END (_Unwind_Resume)
--- /dev/null
+++ b/sysdeps/arm/pt-arm-unwind-resume.S
@@ -0,0 +1,2 @@ 
+#define __libgcc_s_init	pthread_cancel_init
+#include <arm-unwind-resume.S>
--- /dev/null
+++ b/sysdeps/arm/rt-arm-unwind-resume.S
@@ -0,0 +1 @@ 
+#include <arm-unwind-resume.S>
--- /dev/null
+++ b/sysdeps/arm/unwind-resume.h
@@ -0,0 +1,33 @@ 
+/* Definitions for unwind-resume.c.  ARM (EABI) version.
+   Copyright (C) 2014 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; see the file COPYING.LIB.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+/* The EABI personality routine has a different signature than the
+   canonical one.  These macros tell sysdeps/gnu/unwind*.c how to
+   define __gcc_personality_v0.  */
+#define PERSONALITY_PROTO                       \
+  (_Unwind_State state,                         \
+   struct _Unwind_Exception *ue_header,         \
+   struct _Unwind_Context *context)
+#define PERSONALITY_ARGS                        \
+  (state, ue_header, context)
+
+/* It's vitally important that _Unwind_Resume not have a stack frame; the
+   ARM unwinder relies on register state at entrance.  So we write this in
+   assembly (see arm-unwind-resume.S).  This macro tells the generic code
+   not to provide the generic C definition.  */
+#define HAVE_ARCH_UNWIND_RESUME                 1
--- /dev/null
+++ b/sysdeps/generic/unwind-resume.h
@@ -0,0 +1,33 @@ 
+/* Definitions for unwind-resume.c.  Generic version.
+   Copyright (C) 2014 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; see the file COPYING.LIB.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+/* These describe the arguments to unwinder personality functions,
+   specifically __gcc_personality_v0.  A machine-specific sysdeps
+   file might define them differently.  */
+#define PERSONALITY_PROTO                       \
+  (int version, _Unwind_Action actions,         \
+   _Unwind_Exception_Class exception_class,     \
+   struct _Unwind_Exception *ue_header,         \
+   struct _Unwind_Context *context)
+#define PERSONALITY_ARGS                                        \
+  (version, actions, exception_class, ue_header, context)
+
+/* This is defined nonzero by a machine-specific sysdeps file if
+   _Unwind_Resume is provided separately and thus the generic C
+   version should not be defined.  */
+#define HAVE_ARCH_UNWIND_RESUME		0
--- a/sysdeps/gnu/unwind-resume.c
+++ b/sysdeps/gnu/unwind-resume.c
@@ -21,15 +21,16 @@ 
 #include <unwind.h>
 #include <gnu/lib-names.h>
 #include <sysdep.h>
+#include <unwind-resume.h>
 
-static void (*libgcc_s_resume) (struct _Unwind_Exception *exc)
-  __attribute__ ((noreturn));
-static _Unwind_Reason_Code (*libgcc_s_personality)
-  (int, _Unwind_Action, _Unwind_Exception_Class, struct _Unwind_Exception *,
-   struct _Unwind_Context *);
 
-static void
-init (void)
+void (*__libgcc_s_resume) (struct _Unwind_Exception *exc)
+  attribute_hidden __attribute__ ((noreturn));
+
+static _Unwind_Reason_Code (*libgcc_s_personality) PERSONALITY_PROTO;
+
+void attribute_hidden __attribute__ ((cold))
+__libgcc_s_init (void)
 {
   void *resume, *personality;
   void *handle;
@@ -43,33 +44,31 @@  init (void)
                   " must be installed for pthread_cancel to work\n");
 
   PTR_MANGLE (resume);
-  libgcc_s_resume = resume;
+  __libgcc_s_resume = resume;
   PTR_MANGLE (personality);
   libgcc_s_personality = personality;
 }
 
+#if !HAVE_ARCH_UNWIND_RESUME
 void
 _Unwind_Resume (struct _Unwind_Exception *exc)
 {
-  if (__glibc_unlikely (libgcc_s_resume == NULL))
-    init ();
+  if (__glibc_unlikely (__libgcc_s_resume == NULL))
+    __libgcc_s_init ();
 
-  __typeof (libgcc_s_resume) resume = libgcc_s_resume;
+  __typeof (__libgcc_s_resume) resume = __libgcc_s_resume;
   PTR_DEMANGLE (resume);
   (*resume) (exc);
 }
+#endif
 
 _Unwind_Reason_Code
-__gcc_personality_v0 (int version, _Unwind_Action actions,
-		      _Unwind_Exception_Class exception_class,
-                      struct _Unwind_Exception *ue_header,
-                      struct _Unwind_Context *context)
+__gcc_personality_v0 PERSONALITY_PROTO
 {
   if (__glibc_unlikely (libgcc_s_personality == NULL))
-    init ();
+    __libgcc_s_init ();
 
   __typeof (libgcc_s_personality) personality = libgcc_s_personality;
   PTR_DEMANGLE (personality);
-
-  return (*personality) (version, actions, exception_class, ue_header, context);
+  return (*personality) PERSONALITY_ARGS;
 }
--- a/sysdeps/nptl/unwind-forcedunwind.c
+++ b/sysdeps/nptl/unwind-forcedunwind.c
@@ -22,12 +22,12 @@ 
 #include <pthreadP.h>
 #include <sysdep.h>
 #include <gnu/lib-names.h>
+#include <unwind-resume.h>
 
 static void *libgcc_s_handle;
-static void (*libgcc_s_resume) (struct _Unwind_Exception *exc);
-static _Unwind_Reason_Code (*libgcc_s_personality)
-  (int, _Unwind_Action, _Unwind_Exception_Class, struct _Unwind_Exception *,
-   struct _Unwind_Context *);
+void (*__libgcc_s_resume) (struct _Unwind_Exception *exc)
+  attribute_hidden __attribute__ ((noreturn));
+static _Unwind_Reason_Code (*libgcc_s_personality) PERSONALITY_PROTO;
 static _Unwind_Reason_Code (*libgcc_s_forcedunwind)
   (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *);
 static _Unwind_Word (*libgcc_s_getcfa) (struct _Unwind_Context *);
@@ -64,7 +64,7 @@  pthread_cancel_init (void)
     __libc_fatal (LIBGCC_S_SO " must be installed for pthread_cancel to work\n");
 
   PTR_MANGLE (resume);
-  libgcc_s_resume = resume;
+  __libgcc_s_resume = resume;
   PTR_MANGLE (personality);
   libgcc_s_personality = personality;
   PTR_MANGLE (forcedunwind);
@@ -90,6 +90,7 @@  __unwind_freeres (void)
     }
 }
 
+#if !HAVE_ARCH_UNWIND_RESUME
 void
 _Unwind_Resume (struct _Unwind_Exception *exc)
 {
@@ -98,27 +99,23 @@  _Unwind_Resume (struct _Unwind_Exception *exc)
   else
     atomic_read_barrier ();
 
-  void (*resume) (struct _Unwind_Exception *exc) = libgcc_s_resume;
+  void (*resume) (struct _Unwind_Exception *exc) = __libgcc_s_resume;
   PTR_DEMANGLE (resume);
   resume (exc);
 }
+#endif
 
 _Unwind_Reason_Code
-__gcc_personality_v0 (int version, _Unwind_Action actions,
-		      _Unwind_Exception_Class exception_class,
-		      struct _Unwind_Exception *ue_header,
-		      struct _Unwind_Context *context)
+__gcc_personality_v0 PERSONALITY_PROTO
 {
   if (__glibc_unlikely (libgcc_s_handle == NULL))
     pthread_cancel_init ();
   else
     atomic_read_barrier ();
 
-  _Unwind_Reason_Code (*personality)
-    (int, _Unwind_Action, _Unwind_Exception_Class, struct _Unwind_Exception *,
-     struct _Unwind_Context *) = libgcc_s_personality;
+  __typeof (libgcc_s_personality) personality = libgcc_s_personality;
   PTR_DEMANGLE (personality);
-  return personality (version, actions, exception_class, ue_header, context);
+  return (*personality) PERSONALITY_ARGS;
 }
 
 _Unwind_Reason_Code
--- a/sysdeps/unix/sysv/linux/arm/unwind-forcedunwind.c
+++ /dev/null
@@ -1,158 +0,0 @@ 
-/* Copyright (C) 2003-2014 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Jakub Jelinek <jakub@redhat.com>.
-
-   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 <dlfcn.h>
-#include <stdio.h>
-#include <unwind.h>
-#include <pthreadP.h>
-
-static void *libgcc_s_handle;
-static void (*libgcc_s_resume) (struct _Unwind_Exception *exc)
-  __attribute_used__;
-static _Unwind_Reason_Code (*libgcc_s_personality)
-  (_Unwind_State, struct _Unwind_Exception *, struct _Unwind_Context *);
-static _Unwind_Reason_Code (*libgcc_s_forcedunwind)
-  (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *);
-static _Unwind_Word (*libgcc_s_getcfa) (struct _Unwind_Context *);
-
-void
-__attribute_noinline__
-pthread_cancel_init (void)
-{
-  void *resume, *personality, *forcedunwind, *getcfa;
-  void *handle;
-
-  if (__builtin_expect (libgcc_s_handle != NULL, 1))
-    {
-      /* Force gcc to reload all values.  */
-      asm volatile ("" ::: "memory");
-      return;
-    }
-
-  handle = __libc_dlopen ("libgcc_s.so.1");
-
-  if (handle == NULL
-      || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
-      || (personality = __libc_dlsym (handle, "__gcc_personality_v0")) == NULL
-      || (forcedunwind = __libc_dlsym (handle, "_Unwind_ForcedUnwind"))
-	 == NULL
-      || (getcfa = __libc_dlsym (handle, "_Unwind_GetCFA")) == NULL
-#ifdef ARCH_CANCEL_INIT
-      || ARCH_CANCEL_INIT (handle)
-#endif
-      )
-    __libc_fatal ("libgcc_s.so.1 must be installed for pthread_cancel to work\n");
-
-  libgcc_s_resume = resume;
-  libgcc_s_personality = personality;
-  libgcc_s_forcedunwind = forcedunwind;
-  libgcc_s_getcfa = getcfa;
-  /* Make sure libgcc_s_getcfa is written last.  Otherwise,
-     pthread_cancel_init might return early even when the pointer the
-     caller is interested in is not initialized yet.  */
-  atomic_write_barrier ();
-  libgcc_s_handle = handle;
-}
-
-void
-__libc_freeres_fn_section
-__unwind_freeres (void)
-{
-  void *handle = libgcc_s_handle;
-  if (handle != NULL)
-    {
-      libgcc_s_handle = NULL;
-      __libc_dlclose (handle);
-    }
-}
-
-/* It's vitally important that _Unwind_Resume not have a stack frame; the
-   ARM unwinder relies on register state at entrance.  So we write this in
-   assembly.  */
-
-#define STR1(S) #S
-#define STR(S)  STR1(S)
-
-asm (
-"	.globl	_Unwind_Resume\n"
-"	.type	_Unwind_Resume, %function\n"
-"_Unwind_Resume:\n"
-"	.cfi_sections .debug_frame\n"
-"	" CFI_STARTPROC "\n"
-"	push	{r4, r5, r6, lr}\n"
-"	" CFI_ADJUST_CFA_OFFSET (16)" \n"
-"	" CFI_REL_OFFSET (r4, 0) "\n"
-"	" CFI_REL_OFFSET (r5, 4) "\n"
-"	" CFI_REL_OFFSET (r6, 8) "\n"
-"	" CFI_REL_OFFSET (lr, 12) "\n"
-"	" CFI_REMEMBER_STATE "\n"
-"	ldr	r4, 1f\n"
-"	ldr	r5, 2f\n"
-"3:	add	r4, pc, r4\n"
-"	ldr	r3, [r4, r5]\n"
-"	mov	r6, r0\n"
-"	cmp	r3, #0\n"
-"	beq	4f\n"
-"5:	mov	r0, r6\n"
-"	pop	{r4, r5, r6, lr}\n"
-"	" CFI_ADJUST_CFA_OFFSET (-16) "\n"
-"	" CFI_RESTORE (r4) "\n"
-"	" CFI_RESTORE (r5) "\n"
-"	" CFI_RESTORE (r6) "\n"
-"	" CFI_RESTORE (lr) "\n"
-"	bx	r3\n"
-"	" CFI_RESTORE_STATE "\n"
-"4:	bl	pthread_cancel_init\n"
-"	ldr	r3, [r4, r5]\n"
-"	b	5b\n"
-"	" CFI_ENDPROC "\n"
-"	.align 2\n"
-"1:	.word	_GLOBAL_OFFSET_TABLE_ - 3b - " STR (PC_OFS) "\n"
-"2:	.word	libgcc_s_resume(GOTOFF)\n"
-"	.size	_Unwind_Resume, .-_Unwind_Resume\n"
-);
-
-_Unwind_Reason_Code
-__gcc_personality_v0 (_Unwind_State state,
-		      struct _Unwind_Exception *ue_header,
-		      struct _Unwind_Context *context)
-{
-  if (__builtin_expect (libgcc_s_personality == NULL, 0))
-    pthread_cancel_init ();
-
-  return libgcc_s_personality (state, ue_header, context);
-}
-
-_Unwind_Reason_Code
-_Unwind_ForcedUnwind (struct _Unwind_Exception *exc, _Unwind_Stop_Fn stop,
-		      void *stop_argument)
-{
-  if (__builtin_expect (libgcc_s_forcedunwind == NULL, 0))
-    pthread_cancel_init ();
-
-  return libgcc_s_forcedunwind (exc, stop, stop_argument);
-}
-
-_Unwind_Word
-_Unwind_GetCFA (struct _Unwind_Context *context)
-{
-  if (__builtin_expect (libgcc_s_getcfa == NULL, 0))
-    pthread_cancel_init ();
-
-  return libgcc_s_getcfa (context);
-}
--- a/sysdeps/unix/sysv/linux/arm/unwind-resume.c
+++ /dev/null
@@ -1,101 +0,0 @@ 
-/* Copyright (C) 2003-2014 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Jakub Jelinek <jakub@redhat.com>.
-
-   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 <dlfcn.h>
-#include <stdio.h>
-#include <unwind.h>
-
-static void (*libgcc_s_resume) (struct _Unwind_Exception *exc)
-  __attribute_used__;
-static _Unwind_Reason_Code (*libgcc_s_personality)
-  (_Unwind_State, struct _Unwind_Exception *, struct _Unwind_Context *);
-
-static void init (void) __attribute_used__;
-
-static void
-init (void)
-{
-  void *resume, *personality;
-  void *handle;
-
-  handle = __libc_dlopen ("libgcc_s.so.1");
-
-  if (handle == NULL
-      || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
-      || (personality = __libc_dlsym (handle, "__gcc_personality_v0")) == NULL)
-    __libc_fatal ("libgcc_s.so.1 must be installed for pthread_cancel to work\n");
-
-  libgcc_s_resume = resume;
-  libgcc_s_personality = personality;
-}
-
-/* It's vitally important that _Unwind_Resume not have a stack frame; the
-   ARM unwinder relies on register state at entrance.  So we write this in
-   assembly.  */
-
-#define STR1(S) #S
-#define STR(S)  STR1(S)
-
-asm (
-"	.globl	_Unwind_Resume\n"
-"	.type	_Unwind_Resume, %function\n"
-"_Unwind_Resume:\n"
-"	.cfi_sections .debug_frame\n"
-"	" CFI_STARTPROC "\n"
-"	push	{r4, r5, r6, lr}\n"
-"	" CFI_ADJUST_CFA_OFFSET (16)" \n"
-"	" CFI_REL_OFFSET (r4, 0) "\n"
-"	" CFI_REL_OFFSET (r5, 4) "\n"
-"	" CFI_REL_OFFSET (r6, 8) "\n"
-"	" CFI_REL_OFFSET (lr, 12) "\n"
-"	" CFI_REMEMBER_STATE "\n"
-"	ldr	r4, 1f\n"
-"	ldr	r5, 2f\n"
-"3:	add	r4, pc, r4\n"
-"	ldr	r3, [r4, r5]\n"
-"	mov	r6, r0\n"
-"	cmp	r3, #0\n"
-"	beq	4f\n"
-"5:	mov	r0, r6\n"
-"	pop	{r4, r5, r6, lr}\n"
-"	" CFI_ADJUST_CFA_OFFSET (-16) "\n"
-"	" CFI_RESTORE (r4) "\n"
-"	" CFI_RESTORE (r5) "\n"
-"	" CFI_RESTORE (r6) "\n"
-"	" CFI_RESTORE (lr) "\n"
-"	bx	r3\n"
-"	" CFI_RESTORE_STATE "\n"
-"4:	bl	init\n"
-"	ldr	r3, [r4, r5]\n"
-"	b	5b\n"
-"	" CFI_ENDPROC "\n"
-"	.align 2\n"
-"1:	.word	_GLOBAL_OFFSET_TABLE_ - 3b - " STR (PC_OFS) "\n"
-"2:	.word	libgcc_s_resume(GOTOFF)\n"
-"	.size	_Unwind_Resume, .-_Unwind_Resume\n"
-);
-
-_Unwind_Reason_Code
-__gcc_personality_v0 (_Unwind_State state,
-		      struct _Unwind_Exception *ue_header,
-		      struct _Unwind_Context *context)
-{
-  if (__builtin_expect (libgcc_s_personality == NULL, 0))
-    init ();
-  return libgcc_s_personality (state, ue_header, context);
-}