nptl/sysdeps/pthread/unwind-forcedunwind.c

   1 /* Copyright (C) 2003, 2005, 2006 Free Software Foundation, Inc.
   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
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <dlfcn.h>
  21 #include <stdio.h>
  22 #include <unwind.h>
  23 #include <pthreadP.h>
  24
  25 static void (*libgcc_s_resume) (struct _Unwind_Exception *exc);
  26 static _Unwind_Reason_Code (*libgcc_s_personality)
  27   (int, _Unwind_Action, _Unwind_Exception_Class, struct _Unwind_Exception *,
  28    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
  34 __attribute_noinline__
  35 pthread_cancel_init (void)
  36 {
  37   void *resume, *personality, *forcedunwind, *getcfa;
  38   void *handle;
  39
  40   if (__builtin_expect (libgcc_s_getcfa != NULL, 1))
  41     {
  42       /* Force gcc to reload all values.  */
  43       asm volatile ("" ::: "memory");
  44       return;
  45     }
  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;
  64   /* Make sure libgcc_s_getcfa is written last.  Otherwise,
  65      pthread_cancel_init might return early even when the pointer the
  66      caller is interested in is not initialized yet.  */
  67   atomic_write_barrier ();
  68   libgcc_s_getcfa = getcfa;
  69 }
  70
  71 void
  72 _Unwind_Resume (struct _Unwind_Exception *exc)
  73 {
  74   if (__builtin_expect (libgcc_s_resume == NULL, 0))
  75     pthread_cancel_init ();
  76
  77   libgcc_s_resume (exc);
  78 }
  79
  80 _Unwind_Reason_Code
  81 __gcc_personality_v0 (int version, _Unwind_Action actions,
  82                       _Unwind_Exception_Class exception_class,
  83                       struct _Unwind_Exception *ue_header,
  84                       struct _Unwind_Context *context)
  85 {
  86   if (__builtin_expect (libgcc_s_personality == NULL, 0))
  87     pthread_cancel_init ();
  88
  89   return libgcc_s_personality (version, actions, exception_class,
  90                                ue_header, context);
  91 }
  92
  93 _Unwind_Reason_Code
  94 _Unwind_ForcedUnwind (struct _Unwind_Exception *exc, _Unwind_Stop_Fn stop,
  95                       void *stop_argument)
  96 {
  97   if (__builtin_expect (libgcc_s_forcedunwind == NULL, 0))
  98     pthread_cancel_init ();
  99
 100   return libgcc_s_forcedunwind (exc, stop, stop_argument);
 101 }
 102
 103 _Unwind_Word
 104 _Unwind_GetCFA (struct _Unwind_Context *context)
 105 {
 106   if (__builtin_expect (libgcc_s_getcfa == NULL, 0))
 107     pthread_cancel_init ();
 108
 109   return libgcc_s_getcfa (context);
 110 }