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nptl: Use <unwind-link.h> for accessing the libgcc_s unwinder

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Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Florian Weimer 2021-03-01 15:56:36 +01:00
parent 6b7efa3d87
commit 97e42bd482
7 changed files with 50 additions and 146 deletions
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1
nptl/nptlfreeres.c
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@ -27,5 +27,4 @@ __libpthread_freeres (void)
{
call_function_static_weak (__default_pthread_attr_freeres);
call_function_static_weak (__nptl_stacks_freeres);
call_function_static_weak (__nptl_unwind_freeres);
}

6
nptl/pthreadP.h
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@ -287,9 +287,11 @@ hidden_proto (__pthread_unwind_next)
hidden_proto (__pthread_register_cancel)
hidden_proto (__pthread_unregister_cancel)
# ifdef SHARED
extern void attribute_hidden pthread_cancel_init (void);
/* The difference from __libc_unwind_link_get is that here, errors
terminate the process. */
struct unwind_link ;
struct unwind_link *__pthread_unwind_link_get (void) attribute_hidden;
# endif
extern void __nptl_unwind_freeres (void) attribute_hidden;
#endif

3
nptl/pthread_cancel.c
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@ -35,7 +35,8 @@ __pthread_cancel (pthread_t th)
return ESRCH;
#ifdef SHARED
pthread_cancel_init ();
/* Trigger an error if libgcc_s cannot be loaded. */
__pthread_unwind_link_get ();
#endif
int result = 0;
int oldval;

25
sysdeps/arm/nptl/unwind-forcedunwind.c Normal file
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@ -0,0 +1,25 @@
/* Unwinder function forwarders for libpthread. Arm version.
Copyright (C) 2021 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 <https://www.gnu.org/licenses/>. */
#include <sysdeps/nptl/unwind-forcedunwind.c>
void *
__unwind_link_get_resume (void)
{
return UNWIND_LINK_PTR (__pthread_unwind_link_get (), _Unwind_Resume);
}

30
sysdeps/arm/pt-arm-unwind-resume.S
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@ -16,31 +16,5 @@
License along with the GNU C Library. If not, see
<https://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 need to save and restore LR (for our own return address)
and R0 (for the argument to _Unwind_Resume) around the call. */
1: push {r0, lr}
cfi_adjust_cfa_offset (8)
cfi_rel_offset (r0, 0)
cfi_rel_offset (lr, 4)
bl pthread_cancel_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)
/* The implementation in libpthread is identical to the one in libc. */
#include <sysdeps/arm/arm-unwind-resume.S>

115
sysdeps/nptl/unwind-forcedunwind.c
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@ -16,134 +16,49 @@
License along with the GNU C Library; see the file COPYING.LIB. If
not, see <https://www.gnu.org/licenses/>. */
#include <dlfcn.h>
#include <stdio.h>
#include <unwind.h>
#include <unwind-link.h>
#include <pthreadP.h>
#include <sysdep.h>
#include <gnu/lib-names.h>
#include <unwind-resume.h>
static void *libgcc_s_handle;
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 *);
void
__attribute_noinline__
pthread_cancel_init (void)
struct unwind_link *
__pthread_unwind_link_get (void)
{
void *resume;
void *personality;
void *forcedunwind;
void *getcfa;
void *handle;
if (__glibc_likely (libgcc_s_handle != NULL))
{
/* Force gcc to reload all values. */
asm volatile ("" ::: "memory");
return;
}
/* See include/dlfcn.h. Use of __libc_dlopen requires RTLD_NOW. */
handle = __libc_dlopen (LIBGCC_S_SO);
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 " must be installed for pthread_cancel to work\n");
PTR_MANGLE (resume);
__libgcc_s_resume = resume;
PTR_MANGLE (personality);
libgcc_s_personality = personality;
PTR_MANGLE (forcedunwind);
libgcc_s_forcedunwind = forcedunwind;
PTR_MANGLE (getcfa);
libgcc_s_getcfa = getcfa;
/* Make sure libgcc_s_handle 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;
}
/* Register for cleanup in libpthread.so. */
void
__nptl_unwind_freeres (void)
{
void *handle = libgcc_s_handle;
if (handle != NULL)
{
libgcc_s_handle = NULL;
__libc_dlclose (handle);
}
struct unwind_link *unwind_link = __libc_unwind_link_get ();
if (unwind_link == NULL)
__libc_fatal (LIBGCC_S_SO
" must be installed for pthread_cancel to work\n");
return unwind_link;
}
#if !HAVE_ARCH_UNWIND_RESUME
void
_Unwind_Resume (struct _Unwind_Exception *exc)
{
if (__glibc_unlikely (libgcc_s_handle == NULL))
pthread_cancel_init ();
else
atomic_read_barrier ();
void (*resume) (struct _Unwind_Exception *exc) = __libgcc_s_resume;
PTR_DEMANGLE (resume);
resume (exc);
UNWIND_LINK_PTR (__pthread_unwind_link_get (), _Unwind_Resume) (exc);
}
#endif
_Unwind_Reason_Code
__gcc_personality_v0 PERSONALITY_PROTO
{
if (__glibc_unlikely (libgcc_s_handle == NULL))
pthread_cancel_init ();
else
atomic_read_barrier ();
__typeof (libgcc_s_personality) personality = libgcc_s_personality;
PTR_DEMANGLE (personality);
return (*personality) PERSONALITY_ARGS;
return UNWIND_LINK_PTR (__pthread_unwind_link_get (), personality)
PERSONALITY_ARGS;
}
_Unwind_Reason_Code
_Unwind_ForcedUnwind (struct _Unwind_Exception *exc, _Unwind_Stop_Fn stop,
void *stop_argument)
{
if (__glibc_unlikely (libgcc_s_handle == NULL))
pthread_cancel_init ();
else
atomic_read_barrier ();
_Unwind_Reason_Code (*forcedunwind)
(struct _Unwind_Exception *, _Unwind_Stop_Fn, void *)
= libgcc_s_forcedunwind;
PTR_DEMANGLE (forcedunwind);
return forcedunwind (exc, stop, stop_argument);
return UNWIND_LINK_PTR (__pthread_unwind_link_get (), _Unwind_ForcedUnwind)
(exc, stop, stop_argument);
}
_Unwind_Word
_Unwind_GetCFA (struct _Unwind_Context *context)
{
if (__glibc_unlikely (libgcc_s_handle == NULL))
pthread_cancel_init ();
else
atomic_read_barrier ();
_Unwind_Word (*getcfa) (struct _Unwind_Context *) = libgcc_s_getcfa;
PTR_DEMANGLE (getcfa);
return getcfa (context);
return UNWIND_LINK_PTR (__pthread_unwind_link_get (), _Unwind_GetCFA)
(context);
}

16
sysdeps/unix/sysv/linux/ia64/unwind-forcedunwind.c
View File

@ -16,23 +16,11 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <dlfcn.h>
#include <stdio.h>
#include <unwind.h>
#include <pthreadP.h>
static _Unwind_Word (*libgcc_s_getbsp) (struct _Unwind_Context *);
#define ARCH_CANCEL_INIT(handle) \
((libgcc_s_getbsp = __libc_dlsym (handle, "_Unwind_GetBSP")) == NULL)
#include <sysdeps/nptl/unwind-forcedunwind.c>
_Unwind_Word
_Unwind_GetBSP (struct _Unwind_Context *context)
{
if (__builtin_expect (libgcc_s_getbsp == NULL, 0))
pthread_cancel_init ();
return libgcc_s_getbsp (context);
return UNWIND_LINK_PTR (__pthread_unwind_link_get (), _Unwind_GetBSP)
(context);
}