nptl/sysdeps/pthread/unwind-forcedunwind.c

   1 /* Copyright (C) 2003, 2005, 2006, 2009, 2011 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 #include <libgcc_s.h>
  26
  27 static void *libgcc_s_handle;
  28 static void (*libgcc_s_resume) (struct _Unwind_Exception *exc);
  29 static _Unwind_Reason_Code (*libgcc_s_personality)
  30   (int, _Unwind_Action, _Unwind_Exception_Class, struct _Unwind_Exception *,
  31    struct _Unwind_Context *);
  32 static _Unwind_Reason_Code (*libgcc_s_forcedunwind)
  33   (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *);
  34 static _Unwind_Word (*libgcc_s_getcfa) (struct _Unwind_Context *);
  35
  36 void
  37 __attribute_noinline__
  38 pthread_cancel_init (void)
  39 {
  40   void *resume;
  41   void *personality;
  42   void *forcedunwind;
  43   void *getcfa;
  44   void *handle;
  45
  46   if (__builtin_expect (libgcc_s_handle != NULL, 1))
  47     {
  48       /* Force gcc to reload all values.  */
  49       asm volatile ("" ::: "memory");
  50       return;
  51     }
  52
  53   handle = __libc_dlopen (LIBGCC_S_SO);
  54
  55   if (handle == NULL
  56       || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
  57       || (personality = __libc_dlsym (handle, "__gcc_personality_v0")) == NULL
  58       || (forcedunwind = __libc_dlsym (handle, "_Unwind_ForcedUnwind"))
  59          == NULL
  60       || (getcfa = __libc_dlsym (handle, "_Unwind_GetCFA")) == NULL
  61 #ifdef ARCH_CANCEL_INIT
  62       || ARCH_CANCEL_INIT (handle)
  63 #endif
  64       )
  65     __libc_fatal (LIBGCC_S_SO " must be installed for pthread_cancel to work\n");
  66
  67   PTR_MANGLE (resume);
  68   libgcc_s_resume = resume;
  69   PTR_MANGLE (personality);
  70   libgcc_s_personality = personality;
  71   PTR_MANGLE (forcedunwind);
  72   libgcc_s_forcedunwind = forcedunwind;
  73   PTR_MANGLE (getcfa);
  74   libgcc_s_getcfa = getcfa;
  75   /* Make sure libgcc_s_handle is written last.  Otherwise,
  76      pthread_cancel_init might return early even when the pointer the
  77      caller is interested in is not initialized yet.  */
  78   atomic_write_barrier ();
  79   libgcc_s_handle = handle;
  80 }
  81
  82 void
  83 __libc_freeres_fn_section
  84 __unwind_freeres (void)
  85 {
  86   void *handle = libgcc_s_handle;
  87   if (handle != NULL)
  88     {
  89       libgcc_s_handle = NULL;
  90       __libc_dlclose (handle);
  91     }
  92 }
  93
  94 void
  95 _Unwind_Resume (struct _Unwind_Exception *exc)
  96 {
  97   if (__builtin_expect (libgcc_s_handle == NULL, 0))
  98     pthread_cancel_init ();
  99   else
 100     atomic_read_barrier ();
 101
 102   void (*resume) (struct _Unwind_Exception *exc) = libgcc_s_resume;
 103   PTR_DEMANGLE (resume);
 104   resume (exc);
 105 }
 106
 107 _Unwind_Reason_Code
 108 __gcc_personality_v0 (int version, _Unwind_Action actions,
 109                       _Unwind_Exception_Class exception_class,
 110                       struct _Unwind_Exception *ue_header,
 111                       struct _Unwind_Context *context)
 112 {
 113   if (__builtin_expect (libgcc_s_handle == NULL, 0))
 114     pthread_cancel_init ();
 115   else
 116     atomic_read_barrier ();
 117
 118   _Unwind_Reason_Code (*personality)
 119     (int, _Unwind_Action, _Unwind_Exception_Class, struct _Unwind_Exception *,
 120      struct _Unwind_Context *) = libgcc_s_personality;
 121   PTR_DEMANGLE (personality);
 122   return personality (version, actions, exception_class, ue_header, context);
 123 }
 124
 125 _Unwind_Reason_Code
 126 _Unwind_ForcedUnwind (struct _Unwind_Exception *exc, _Unwind_Stop_Fn stop,
 127                       void *stop_argument)
 128 {
 129   if (__builtin_expect (libgcc_s_handle == NULL, 0))
 130     pthread_cancel_init ();
 131   else
 132     atomic_read_barrier ();
 133
 134   _Unwind_Reason_Code (*forcedunwind)
 135     (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *)
 136     = libgcc_s_forcedunwind;
 137   PTR_DEMANGLE (forcedunwind);
 138   return forcedunwind (exc, stop, stop_argument);
 139 }
 140
 141 _Unwind_Word
 142 _Unwind_GetCFA (struct _Unwind_Context *context)
 143 {
 144   if (__builtin_expect (libgcc_s_handle == NULL, 0))
 145     pthread_cancel_init ();
 146   else
 147     atomic_read_barrier ();
 148
 149   _Unwind_Word (*getcfa) (struct _Unwind_Context *) = libgcc_s_getcfa;
 150   PTR_DEMANGLE (getcfa);
 151   return getcfa (context);
 152 }