gcc/unwind-sjlj.c

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