nptl/sysdeps/pthread/unwind-forcedunwind.c

   1 /* Copyright (C) 2003, 2005, 2006, 2009 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 #include <sysdep.h>
  25
  26 static void *libgcc_s_handle;
  27 static void (*libgcc_s_resume) (struct _Unwind_Exception *exc);
  28 static _Unwind_Reason_Code (*libgcc_s_personality)
  29   (int, _Unwind_Action, _Unwind_Exception_Class, struct _Unwind_Exception *,
  30    struct _Unwind_Context *);
  31 static _Unwind_Reason_Code (*libgcc_s_forcedunwind)
  32   (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *);
  33 static _Unwind_Word (*libgcc_s_getcfa) (struct _Unwind_Context *);
  34
  35 void
  36 __attribute_noinline__
  37 pthread_cancel_init (void)
  38 {
  39   void *resume;
  40   void *personality;
  41   void *forcedunwind;
  42   void *getcfa;
  43   void *handle;
  44
  45   if (__builtin_expect (libgcc_s_handle != NULL, 1))
  46     {
  47       /* Force gcc to reload all values.  */
  48       asm volatile ("" ::: "memory");
  49       return;
  50     }
  51
  52   handle = __libc_dlopen ("libgcc_s.so.1");
  53
  54   if (handle == NULL
  55       || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
  56       || (personality = __libc_dlsym (handle, "__gcc_personality_v0")) == NULL
  57       || (forcedunwind = __libc_dlsym (handle, "_Unwind_ForcedUnwind"))
  58          == NULL
  59       || (getcfa = __libc_dlsym (handle, "_Unwind_GetCFA")) == NULL
  60 #ifdef ARCH_CANCEL_INIT
  61       || ARCH_CANCEL_INIT (handle)
  62 #endif
  63       )
  64     __libc_fatal ("libgcc_s.so.1 must be installed for pthread_cancel to work\n");
  65
  66   PTR_MANGLE (resume);
  67   libgcc_s_resume = resume;
  68   PTR_MANGLE (personality);
  69   libgcc_s_personality = personality;
  70   PTR_MANGLE (forcedunwind);
  71   libgcc_s_forcedunwind = forcedunwind;
  72   PTR_MANGLE (getcfa);
  73   libgcc_s_getcfa = getcfa;
  74   /* Make sure libgcc_s_handle is written last.  Otherwise,
  75      pthread_cancel_init might return early even when the pointer the
  76      caller is interested in is not initialized yet.  */
  77   atomic_write_barrier ();
  78   libgcc_s_handle = handle;
  79 }
  80
  81 void
  82 __libc_freeres_fn_section
  83 __unwind_freeres (void)
  84 {
  85   void *handle = libgcc_s_handle;
  86   if (handle != NULL)
  87     {
  88       libgcc_s_handle = NULL;
  89       __libc_dlclose (handle);
  90     }
  91 }
  92
  93 void
  94 _Unwind_Resume (struct _Unwind_Exception *exc)
  95 {
  96   if (__builtin_expect (libgcc_s_handle == NULL, 0))
  97     pthread_cancel_init ();
  98
  99   void (*resume) (struct _Unwind_Exception *exc) = libgcc_s_resume;
 100   PTR_DEMANGLE (resume);
 101   resume (exc);
 102 }
 103
 104 _Unwind_Reason_Code
 105 __gcc_personality_v0 (int version, _Unwind_Action actions,
 106                       _Unwind_Exception_Class exception_class,
 107                       struct _Unwind_Exception *ue_header,
 108                       struct _Unwind_Context *context)
 109 {
 110   if (__builtin_expect (libgcc_s_handle == NULL, 0))
 111     pthread_cancel_init ();
 112
 113   _Unwind_Reason_Code (*personality)
 114     (int, _Unwind_Action, _Unwind_Exception_Class, struct _Unwind_Exception *,
 115      struct _Unwind_Context *) = libgcc_s_personality;
 116   PTR_DEMANGLE (personality);
 117   return personality (version, actions, exception_class, ue_header, context);
 118 }
 119
 120 _Unwind_Reason_Code
 121 _Unwind_ForcedUnwind (struct _Unwind_Exception *exc, _Unwind_Stop_Fn stop,
 122                       void *stop_argument)
 123 {
 124   if (__builtin_expect (libgcc_s_handle == NULL, 0))
 125     pthread_cancel_init ();
 126
 127   _Unwind_Reason_Code (*forcedunwind)
 128     (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *)
 129     = libgcc_s_forcedunwind;
 130   PTR_DEMANGLE (forcedunwind);
 131   return forcedunwind (exc, stop, stop_argument);
 132 }
 133
 134 _Unwind_Word
 135 _Unwind_GetCFA (struct _Unwind_Context *context)
 136 {
 137   if (__builtin_expect (libgcc_s_handle == NULL, 0))
 138     pthread_cancel_init ();
 139
 140   _Unwind_Word (*getcfa) (struct _Unwind_Context *) = libgcc_s_getcfa;
 141   PTR_DEMANGLE (getcfa);
 142   return getcfa (context);
 143 }