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 (*volatile libgcc_s_resume) (struct _Unwind_Exception *exc);
  26 static _Unwind_Reason_Code (*volatile libgcc_s_personality)
  27   (int, _Unwind_Action, _Unwind_Exception_Class, struct _Unwind_Exception *,
  28    struct _Unwind_Context *);
  29 static _Unwind_Reason_Code (*volatile libgcc_s_forcedunwind)
  30   (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *);
  31 static _Unwind_Word (*volatile libgcc_s_getcfa) (struct _Unwind_Context *);
  32
  33 void
  34 pthread_cancel_init (void)
  35 {
  36   void *resume, *personality, *forcedunwind, *getcfa;
  37   void *handle;
  38
  39   if (__builtin_expect (libgcc_s_getcfa != NULL, 1))
  40     return;
  41
  42   handle = __libc_dlopen ("libgcc_s.so.1");
  43
  44   if (handle == NULL
  45       || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
  46       || (personality = __libc_dlsym (handle, "__gcc_personality_v0")) == NULL
  47       || (forcedunwind = __libc_dlsym (handle, "_Unwind_ForcedUnwind"))
  48          == NULL
  49       || (getcfa = __libc_dlsym (handle, "_Unwind_GetCFA")) == NULL
  50 #ifdef ARCH_CANCEL_INIT
  51       || ARCH_CANCEL_INIT (handle)
  52 #endif
  53       )
  54     __libc_fatal ("libgcc_s.so.1 must be installed for pthread_cancel to work\n");
  55
  56   libgcc_s_resume = resume;
  57   libgcc_s_personality = personality;
  58   libgcc_s_forcedunwind = forcedunwind;
  59   /* Make sure libgcc_s_getcfa is written last.  Otherwise,
  60      pthread_cancel_init might return early even when the pointer the
  61      caller is interested in is not initialized yet.  */
  62   atomic_write_barrier ();
  63   libgcc_s_getcfa = getcfa;
  64 }
  65
  66 void
  67 _Unwind_Resume (struct _Unwind_Exception *exc)
  68 {
  69   if (__builtin_expect (libgcc_s_resume == NULL, 0))
  70     {
  71       pthread_cancel_init ();
  72       /* The function pointer has changed, ensure we reload it.  */
  73       asm volatile ("" : "+m" (libgcc_s_resume));
  74     }
  75   libgcc_s_resume (exc);
  76 }
  77
  78 _Unwind_Reason_Code
  79 __gcc_personality_v0 (int version, _Unwind_Action actions,
  80                       _Unwind_Exception_Class exception_class,
  81                       struct _Unwind_Exception *ue_header,
  82                       struct _Unwind_Context *context)
  83 {
  84   if (__builtin_expect (libgcc_s_personality == NULL, 0))
  85     {
  86       pthread_cancel_init ();
  87       /* The function pointer has changed, ensure we reload it.  */
  88       asm volatile ("" : "+m" (libgcc_s_personality));
  89     }
  90   return libgcc_s_personality (version, actions, exception_class,
  91                                ue_header, context);
  92 }
  93
  94 _Unwind_Reason_Code
  95 _Unwind_ForcedUnwind (struct _Unwind_Exception *exc, _Unwind_Stop_Fn stop,
  96                       void *stop_argument)
  97 {
  98   if (__builtin_expect (libgcc_s_forcedunwind == NULL, 0))
  99     {
 100       pthread_cancel_init ();
 101       /* The function pointer has changed, ensure we reload it.  */
 102       asm volatile ("" : "+m" (libgcc_s_forcedunwind));
 103     }
 104   return libgcc_s_forcedunwind (exc, stop, stop_argument);
 105 }
 106
 107 _Unwind_Word
 108 _Unwind_GetCFA (struct _Unwind_Context *context)
 109 {
 110   if (__builtin_expect (libgcc_s_getcfa == NULL, 0))
 111     {
 112       pthread_cancel_init ();
 113       /* The function pointer has changed, ensure we reload it.  */
 114       asm volatile ("" : "+m" (libgcc_s_getcfa));
 115     }
 116   return libgcc_s_getcfa (context);
 117 }