gcc/unwind-sjlj.c

   1 /* DWARF2 exception handling and frame unwind runtime interface routines.
   2    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002
   3    Free Software Foundation, Inc.
   4
   5    This file is part of GCC.
   6
   7    GCC is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    GCC is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  15    License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with GCC; see the file COPYING.  If not, write to the Free
  19    Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20    02111-1307, USA.  */
  21
  22 #include "tconfig.h"
  23 #include "tsystem.h"
  24 #include "unwind.h"
  25 #include "gthr.h"
  26
  27 #ifdef __USING_SJLJ_EXCEPTIONS__
  28
  29 #ifdef DONT_USE_BUILTIN_SETJMP
  30 #ifndef inhibit_libc
  31 #include <setjmp.h>
  32 #else
  33 typedef void *jmp_buf[JMP_BUF_SIZE];
  34 extern void longjmp(jmp_buf, int) __attribute__((noreturn));
  35 #endif
  36 #else
  37 #define setjmp __builtin_setjmp
  38 #define longjmp __builtin_longjmp
  39 #endif
  40
  41 /* This structure is allocated on the stack of the target function.
  42    This must match the definition created in except.c:init_eh.  */
  43 struct SjLj_Function_Context
  44 {
  45   /* This is the chain through all registered contexts.  It is
  46      filled in by _Unwind_SjLj_Register.  */
  47   struct SjLj_Function_Context *prev;
  48
  49   /* This is assigned in by the target function before every call
  50      to the index of the call site in the lsda.  It is assigned by
  51      the personality routine to the landing pad index.  */
  52   int call_site;
  53
  54   /* This is how data is returned from the personality routine to
  55      the target function's handler.  */
  56   _Unwind_Word data[4];
  57
  58   /* These are filled in once by the target function before any
  59      exceptions are expected to be handled.  */
  60   _Unwind_Personality_Fn personality;
  61   void *lsda;
  62
  63 #ifdef DONT_USE_BUILTIN_SETJMP
  64   /* We don't know what sort of alignment requirements the system
  65      jmp_buf has.  We over estimated in except.c, and now we have
  66      to match that here just in case the system *didn't* have more
  67      restrictive requirements.  */
  68   jmp_buf jbuf __attribute__((aligned));
  69 #else
  70   void *jbuf[];
  71 #endif
  72 };
  73
  74 struct _Unwind_Context
  75 {
  76   struct SjLj_Function_Context *fc;
  77 };
  78
  79 typedef struct
  80 {
  81   _Unwind_Personality_Fn personality;
  82 } _Unwind_FrameState;
  83
  84 \f
  85 /* Manage the chain of registered function contexts.  */
  86
  87 /* Single threaded fallback chain.  */
  88 static struct SjLj_Function_Context *fc_static;
  89
  90 #if __GTHREADS
  91 static __gthread_key_t fc_key;
  92 static int use_fc_key = -1;
  93
  94 static void
  95 fc_key_dtor (void *ptr)
  96 {
  97   __gthread_key_dtor (fc_key, ptr);
  98 }
  99
 100 static void
 101 fc_key_init (void)
 102 {
 103   use_fc_key = __gthread_key_create (&fc_key, fc_key_dtor) == 0;
 104 }
 105
 106 static void
 107 fc_key_init_once (void)
 108 {
 109   static __gthread_once_t once = __GTHREAD_ONCE_INIT;
 110   if (__gthread_once (&once, fc_key_init) != 0 || use_fc_key < 0)
 111     use_fc_key = 0;
 112 }
 113 #endif
 114
 115 void
 116 _Unwind_SjLj_Register (struct SjLj_Function_Context *fc)
 117 {
 118 #if __GTHREADS
 119   if (use_fc_key < 0)
 120     fc_key_init_once ();
 121
 122   if (use_fc_key)
 123     {
 124       fc->prev = __gthread_getspecific (fc_key);
 125       __gthread_setspecific (fc_key, fc);
 126     }
 127   else
 128 #endif
 129     {
 130       fc->prev = fc_static;
 131       fc_static = fc;
 132     }
 133 }
 134
 135 static inline struct SjLj_Function_Context *
 136 _Unwind_SjLj_GetContext (void)
 137 {
 138 #if __GTHREADS
 139   if (use_fc_key < 0)
 140     fc_key_init_once ();
 141
 142   if (use_fc_key)
 143     return __gthread_getspecific (fc_key);
 144 #endif
 145   return fc_static;
 146 }
 147
 148 static inline void
 149 _Unwind_SjLj_SetContext (struct SjLj_Function_Context *fc)
 150 {
 151 #if __GTHREADS
 152   if (use_fc_key < 0)
 153     fc_key_init_once ();
 154
 155   if (use_fc_key)
 156     __gthread_setspecific (fc_key, fc);
 157   else
 158 #endif
 159     fc_static = fc;
 160 }
 161
 162 void
 163 _Unwind_SjLj_Unregister (struct SjLj_Function_Context *fc)
 164 {
 165   _Unwind_SjLj_SetContext (fc->prev);
 166 }
 167
 168 \f
 169 /* Get/set the return data value at INDEX in CONTEXT.  */
 170
 171 _Unwind_Word
 172 _Unwind_GetGR (struct _Unwind_Context *context, int index)
 173 {
 174   return context->fc->data[index];
 175 }
 176
 177 void
 178 _Unwind_SetGR (struct _Unwind_Context *context, int index, _Unwind_Word val)
 179 {
 180   context->fc->data[index] = val;
 181 }
 182
 183 /* Get the call-site index as saved in CONTEXT.  */
 184
 185 _Unwind_Ptr
 186 _Unwind_GetIP (struct _Unwind_Context *context)
 187 {
 188   return context->fc->call_site + 1;
 189 }
 190
 191 /* Set the return landing pad index in CONTEXT.  */
 192
 193 void
 194 _Unwind_SetIP (struct _Unwind_Context *context, _Unwind_Ptr val)
 195 {
 196   context->fc->call_site = val - 1;
 197 }
 198
 199 void *
 200 _Unwind_GetLanguageSpecificData (struct _Unwind_Context *context)
 201 {
 202   return context->fc->lsda;
 203 }
 204
 205 _Unwind_Ptr
 206 _Unwind_GetRegionStart (struct _Unwind_Context *context __attribute__((unused)) )
 207 {
 208   return 0;
 209 }
 210
 211 #ifndef __ia64__
 212 _Unwind_Ptr
 213 _Unwind_GetDataRelBase (struct _Unwind_Context *context __attribute__((unused)) )
 214 {
 215   return 0;
 216 }
 217
 218 _Unwind_Ptr
 219 _Unwind_GetTextRelBase (struct _Unwind_Context *context __attribute__((unused)) )
 220 {
 221   return 0;
 222 }
 223 #endif
 224 \f
 225 static inline _Unwind_Reason_Code
 226 uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
 227 {
 228   if (context->fc == NULL)
 229     {
 230       fs->personality = NULL;
 231       return _URC_END_OF_STACK;
 232     }
 233   else
 234     {
 235       fs->personality = context->fc->personality;
 236       return _URC_NO_REASON;
 237     }
 238 }
 239
 240 static inline void
 241 uw_update_context (struct _Unwind_Context *context,
 242                    _Unwind_FrameState *fs __attribute__((unused)) )
 243 {
 244   context->fc = context->fc->prev;
 245 }
 246
 247 static inline void
 248 uw_init_context (struct _Unwind_Context *context)
 249 {
 250   context->fc = _Unwind_SjLj_GetContext ();
 251 }
 252
 253 /* ??? There appear to be bugs in integrate.c wrt __builtin_longjmp and
 254    virtual-stack-vars.  An inline version of this segfaults on Sparc.  */
 255 #define uw_install_context(CURRENT, TARGET)             \
 256   do                                                    \
 257     {                                                   \
 258       _Unwind_SjLj_SetContext ((TARGET)->fc);           \
 259       longjmp ((TARGET)->fc->jbuf, 1);                  \
 260     }                                                   \
 261   while (0)
 262
 263
 264 static inline _Unwind_Ptr
 265 uw_identify_context (struct _Unwind_Context *context)
 266 {
 267   return (_Unwind_Ptr) context->fc;
 268 }
 269
 270
 271 /* Play games with unwind symbols so that we can have call frame
 272    and sjlj symbols in the same shared library.  Not that you can
 273    use them simultaneously...  */
 274 #define _Unwind_RaiseException          _Unwind_SjLj_RaiseException
 275 #define _Unwind_ForcedUnwind            _Unwind_SjLj_ForcedUnwind
 276 #define _Unwind_Resume                  _Unwind_SjLj_Resume
 277
 278 #include "unwind.inc"
 279
 280 #endif /* USING_SJLJ_EXCEPTIONS */