[thirdparty/glibc.git] / sysdeps / unix / sysv / linux / arm / unwind-forcedunwind.c

/* Copyright (C) 2003-2015 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);
}
Commit	Line	Data
b168057a	1	/* Copyright (C) 2003-2015 Free Software Foundation, Inc.
02a9f771 DJ	2	This file is part of the GNU C Library.
	3	Contributed by Jakub Jelinek <jakub@redhat.com>.
	4
	5	The GNU C Library is free software; you can redistribute it and/or
	6	modify it under the terms of the GNU Lesser General Public License as
	7	published by the Free Software Foundation; either version 2.1 of the
	8	License, or (at your option) any later version.
	9
	10	The GNU C Library is distributed in the hope that it will be useful,
	11	but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	13	Lesser General Public License for more details.
	14
	15	You should have received a copy of the GNU Lesser General Public
ab84e3ff PE	16	License along with the GNU C Library. If not, see
ab84e3ff PE	17	<http://www.gnu.org/licenses/>. */
02a9f771 DJ	18
	19	#include <dlfcn.h>
	20	#include <stdio.h>
	21	#include <unwind.h>
	22	#include <pthreadP.h>
	23
f281f9cf	24	static void *libgcc_s_handle;
175cef41 JM	25	static void (libgcc_s_resume) (struct _Unwind_Exception exc)
175cef41 JM	26	__attribute_used__;
02a9f771 DJ	27	static _Unwind_Reason_Code (*libgcc_s_personality)
	28	(_Unwind_State, struct _Unwind_Exception , struct _Unwind_Context );
	29	static _Unwind_Reason_Code (*libgcc_s_forcedunwind)
	30	(struct _Unwind_Exception , _Unwind_Stop_Fn, void );
	31	static _Unwind_Word (libgcc_s_getcfa) (struct _Unwind_Context );
	32
	33	void
8323b1ab	34	__attribute_noinline__
02a9f771 DJ	35	pthread_cancel_init (void)
	36	{
	37	void resume, personality, forcedunwind, getcfa;
	38	void *handle;
	39
f281f9cf	40	if (__builtin_expect (libgcc_s_handle != NULL, 1))
8323b1ab DJ	41	{
	42	/* Force gcc to reload all values. */
	43	asm volatile ("" ::: "memory");
	44	return;
	45	}
02a9f771 DJ	46
	47	handle = __libc_dlopen ("libgcc_s.so.1");
	48
	49	if (handle == NULL
	50	\|\| (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
	51	\|\| (personality = __libc_dlsym (handle, "__gcc_personality_v0")) == NULL
	52	\|\| (forcedunwind = __libc_dlsym (handle, "_Unwind_ForcedUnwind"))
	53	== NULL
	54	\|\| (getcfa = __libc_dlsym (handle, "_Unwind_GetCFA")) == NULL
	55	#ifdef ARCH_CANCEL_INIT
	56	\|\| ARCH_CANCEL_INIT (handle)
	57	#endif
	58	)
	59	__libc_fatal ("libgcc_s.so.1 must be installed for pthread_cancel to work\n");
	60
	61	libgcc_s_resume = resume;
	62	libgcc_s_personality = personality;
	63	libgcc_s_forcedunwind = forcedunwind;
f281f9cf	64	libgcc_s_getcfa = getcfa;
8323b1ab DJ	65	/* Make sure libgcc_s_getcfa is written last. Otherwise,
	66	pthread_cancel_init might return early even when the pointer the
	67	caller is interested in is not initialized yet. */
	68	atomic_write_barrier ();
f281f9cf JM	69	libgcc_s_handle = handle;
	70	}
	71
	72	void
	73	__libc_freeres_fn_section
	74	__unwind_freeres (void)
	75	{
	76	void *handle = libgcc_s_handle;
	77	if (handle != NULL)
	78	{
	79	libgcc_s_handle = NULL;
	80	__libc_dlclose (handle);
	81	}
02a9f771 DJ	82	}
	83
	84	/* It's vitally important that _Unwind_Resume not have a stack frame; the
	85	ARM unwinder relies on register state at entrance. So we write this in
	86	assembly. */
	87
783a65c2 RH	88	#define STR1(S) #S
	89	#define STR(S) STR1(S)
	90
02a9f771 DJ	91	asm (
	92	" .globl _Unwind_Resume\n"
	93	" .type _Unwind_Resume, %function\n"
	94	"_Unwind_Resume:\n"
01b32e73 TS	95	" .cfi_sections .debug_frame\n"
01b32e73 TS	96	" " CFI_STARTPROC "\n"
55668624	97	" push {r4, r5, r6, lr}\n"
01b32e73 TS	98	" " CFI_ADJUST_CFA_OFFSET (16)" \n"
	99	" " CFI_REL_OFFSET (r4, 0) "\n"
	100	" " CFI_REL_OFFSET (r5, 4) "\n"
	101	" " CFI_REL_OFFSET (r6, 8) "\n"
	102	" " CFI_REL_OFFSET (lr, 12) "\n"
	103	" " CFI_REMEMBER_STATE "\n"
02a9f771 DJ	104	" ldr r4, 1f\n"
	105	" ldr r5, 2f\n"
	106	"3: add r4, pc, r4\n"
	107	" ldr r3, [r4, r5]\n"
	108	" mov r6, r0\n"
	109	" cmp r3, #0\n"
	110	" beq 4f\n"
	111	"5: mov r0, r6\n"
55668624	112	" pop {r4, r5, r6, lr}\n"
01b32e73 TS	113	" " CFI_ADJUST_CFA_OFFSET (-16) "\n"
	114	" " CFI_RESTORE (r4) "\n"
	115	" " CFI_RESTORE (r5) "\n"
	116	" " CFI_RESTORE (r6) "\n"
	117	" " CFI_RESTORE (lr) "\n"
02a9f771	118	" bx r3\n"
01b32e73	119	" " CFI_RESTORE_STATE "\n"
02a9f771 DJ	120	"4: bl pthread_cancel_init\n"
	121	" ldr r3, [r4, r5]\n"
	122	" b 5b\n"
01b32e73	123	" " CFI_ENDPROC "\n"
5631abde	124	" .align 2\n"
783a65c2	125	"1: .word _GLOBAL_OFFSET_TABLE_ - 3b - " STR (PC_OFS) "\n"
02a9f771 DJ	126	"2: .word libgcc_s_resume(GOTOFF)\n"
	127	" .size _Unwind_Resume, .-_Unwind_Resume\n"
	128	);
	129
	130	_Unwind_Reason_Code
	131	__gcc_personality_v0 (_Unwind_State state,
	132	struct _Unwind_Exception *ue_header,
	133	struct _Unwind_Context *context)
	134	{
	135	if (__builtin_expect (libgcc_s_personality == NULL, 0))
	136	pthread_cancel_init ();
8323b1ab	137
02a9f771 DJ	138	return libgcc_s_personality (state, ue_header, context);
	139	}
	140
	141	_Unwind_Reason_Code
	142	_Unwind_ForcedUnwind (struct _Unwind_Exception *exc, _Unwind_Stop_Fn stop,
	143	void *stop_argument)
	144	{
	145	if (__builtin_expect (libgcc_s_forcedunwind == NULL, 0))
	146	pthread_cancel_init ();
8323b1ab	147
02a9f771 DJ	148	return libgcc_s_forcedunwind (exc, stop, stop_argument);
	149	}
	150
	151	_Unwind_Word
	152	_Unwind_GetCFA (struct _Unwind_Context *context)
	153	{
	154	if (__builtin_expect (libgcc_s_getcfa == NULL, 0))
	155	pthread_cancel_init ();
8323b1ab	156
02a9f771 DJ	157	return libgcc_s_getcfa (context);
02a9f771 DJ	158	}