gcc/unwind-sjlj.c

   1 /* SJLJ exception handling and frame unwind runtime interface routines.
   2    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2006
   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    In addition to the permissions in the GNU General Public License, the
  13    Free Software Foundation gives you unlimited permission to link the
  14    compiled version of this file into combinations with other programs,
  15    and to distribute those combinations without any restriction coming
  16    from the use of this file.  (The General Public License restrictions
  17    do apply in other respects; for example, they cover modification of
  18    the file, and distribution when not linked into a combined
  19    executable.)
  20
  21    GCC is distributed in the hope that it will be useful, but WITHOUT
  22    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  23    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  24    License for more details.
  25
  26    You should have received a copy of the GNU General Public License
  27    along with GCC; see the file COPYING.  If not, write to the Free
  28    Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  29    02110-1301, USA.  */
  30
  31 #include "tconfig.h"
  32 #include "tsystem.h"
  33 #include "coretypes.h"
  34 #include "tm.h"
  35 #include "unwind.h"
  36 #include "gthr.h"
  37
  38 #ifdef __USING_SJLJ_EXCEPTIONS__
  39
  40 #ifdef DONT_USE_BUILTIN_SETJMP
  41 #ifndef inhibit_libc
  42 #include <setjmp.h>
  43 #else
  44 typedef void *jmp_buf[JMP_BUF_SIZE];
  45 extern void longjmp(jmp_buf, int) __attribute__((noreturn));
  46 #endif
  47 #else
  48 #define longjmp __builtin_longjmp
  49 #endif
  50
  51 /* The setjmp side is dealt with in the except.c file.  */
  52 #undef setjmp
  53 #define setjmp setjmp_should_not_be_used_in_this_file
  54
  55
  56 /* This structure is allocated on the stack of the target function.
  57    This must match the definition created in except.c:init_eh.  */
  58 struct SjLj_Function_Context
  59 {
  60   /* This is the chain through all registered contexts.  It is
  61      filled in by _Unwind_SjLj_Register.  */
  62   struct SjLj_Function_Context *prev;
  63
  64   /* This is assigned in by the target function before every call
  65      to the index of the call site in the lsda.  It is assigned by
  66      the personality routine to the landing pad index.  */
  67   int call_site;
  68
  69   /* This is how data is returned from the personality routine to
  70      the target function's handler.  */
  71   _Unwind_Word data[4];
  72
  73   /* These are filled in once by the target function before any
  74      exceptions are expected to be handled.  */
  75   _Unwind_Personality_Fn personality;
  76   void *lsda;
  77
  78 #ifdef DONT_USE_BUILTIN_SETJMP
  79   /* We don't know what sort of alignment requirements the system
  80      jmp_buf has.  We over estimated in except.c, and now we have
  81      to match that here just in case the system *didn't* have more
  82      restrictive requirements.  */
  83   jmp_buf jbuf __attribute__((aligned));
  84 #else
  85   void *jbuf[];
  86 #endif
  87 };
  88
  89 struct _Unwind_Context
  90 {
  91   struct SjLj_Function_Context *fc;
  92 };
  93
  94 typedef struct
  95 {
  96   _Unwind_Personality_Fn personality;
  97 } _Unwind_FrameState;
  98
  99 \f
 100 /* Manage the chain of registered function contexts.  */
 101
 102 /* Single threaded fallback chain.  */
 103 static struct SjLj_Function_Context *fc_static;
 104
 105 #if __GTHREADS
 106 static __gthread_key_t fc_key;
 107 static int use_fc_key = -1;
 108
 109 static void
 110 fc_key_init (void)
 111 {
 112   use_fc_key = __gthread_key_create (&fc_key, 0) == 0;
 113 }
 114
 115 static void
 116 fc_key_init_once (void)
 117 {
 118   static __gthread_once_t once = __GTHREAD_ONCE_INIT;
 119   if (__gthread_once (&once, fc_key_init) != 0 || use_fc_key < 0)
 120     use_fc_key = 0;
 121 }
 122 #endif
 123
 124 void
 125 _Unwind_SjLj_Register (struct SjLj_Function_Context *fc)
 126 {
 127 #if __GTHREADS
 128   if (use_fc_key < 0)
 129     fc_key_init_once ();
 130
 131   if (use_fc_key)
 132     {
 133       fc->prev = __gthread_getspecific (fc_key);
 134       __gthread_setspecific (fc_key, fc);
 135     }
 136   else
 137 #endif
 138     {
 139       fc->prev = fc_static;
 140       fc_static = fc;
 141     }
 142 }
 143
 144 static inline struct SjLj_Function_Context *
 145 _Unwind_SjLj_GetContext (void)
 146 {
 147 #if __GTHREADS
 148   if (use_fc_key < 0)
 149     fc_key_init_once ();
 150
 151   if (use_fc_key)
 152     return __gthread_getspecific (fc_key);
 153 #endif
 154   return fc_static;
 155 }
 156
 157 static inline void
 158 _Unwind_SjLj_SetContext (struct SjLj_Function_Context *fc)
 159 {
 160 #if __GTHREADS
 161   if (use_fc_key < 0)
 162     fc_key_init_once ();
 163
 164   if (use_fc_key)
 165     __gthread_setspecific (fc_key, fc);
 166   else
 167 #endif
 168     fc_static = fc;
 169 }
 170
 171 void
 172 _Unwind_SjLj_Unregister (struct SjLj_Function_Context *fc)
 173 {
 174   _Unwind_SjLj_SetContext (fc->prev);
 175 }
 176
 177 \f
 178 /* Get/set the return data value at INDEX in CONTEXT.  */
 179
 180 _Unwind_Word
 181 _Unwind_GetGR (struct _Unwind_Context *context, int index)
 182 {
 183   return context->fc->data[index];
 184 }
 185
 186 /* Get the value of the CFA as saved in CONTEXT.  */
 187
 188 _Unwind_Word
 189 _Unwind_GetCFA (struct _Unwind_Context *context __attribute__((unused)))
 190 {
 191   /* ??? Ideally __builtin_setjmp places the CFA in the jmpbuf.  */
 192
 193 #ifndef DONT_USE_BUILTIN_SETJMP
 194   /* This is a crude imitation of the CFA: the saved stack pointer.
 195      This is roughly the CFA of the frame before CONTEXT.  When using the
 196      DWARF-2 unwinder _Unwind_GetCFA returns the CFA of the frame described
 197      by CONTEXT instead; but for DWARF-2 the cleanups associated with
 198      CONTEXT have already been run, and for SJLJ they have not yet been.  */
 199   if (context->fc != NULL)
 200     return (_Unwind_Word) context->fc->jbuf[2];
 201 #endif
 202
 203   /* Otherwise we're out of luck for now.  */
 204   return (_Unwind_Word) 0;
 205 }
 206
 207 void
 208 _Unwind_SetGR (struct _Unwind_Context *context, int index, _Unwind_Word val)
 209 {
 210   context->fc->data[index] = val;
 211 }
 212
 213 /* Get the call-site index as saved in CONTEXT.  */
 214
 215 _Unwind_Ptr
 216 _Unwind_GetIP (struct _Unwind_Context *context)
 217 {
 218   return context->fc->call_site + 1;
 219 }
 220
 221 _Unwind_Ptr
 222 _Unwind_GetIPInfo (struct _Unwind_Context *context, int *ip_before_insn)
 223 {
 224   *ip_before_insn = 0;
 225   if (context->fc != NULL)
 226     return context->fc->call_site + 1;
 227   else
 228     return 0;
 229 }
 230
 231 /* Set the return landing pad index in CONTEXT.  */
 232
 233 void
 234 _Unwind_SetIP (struct _Unwind_Context *context, _Unwind_Ptr val)
 235 {
 236   context->fc->call_site = val - 1;
 237 }
 238
 239 void *
 240 _Unwind_GetLanguageSpecificData (struct _Unwind_Context *context)
 241 {
 242   return context->fc->lsda;
 243 }
 244
 245 _Unwind_Ptr
 246 _Unwind_GetRegionStart (struct _Unwind_Context *context __attribute__((unused)) )
 247 {
 248   return 0;
 249 }
 250
 251 void *
 252 _Unwind_FindEnclosingFunction (void *pc __attribute__((unused)))
 253 {
 254   return NULL;
 255 }
 256
 257 #ifndef __ia64__
 258 _Unwind_Ptr
 259 _Unwind_GetDataRelBase (struct _Unwind_Context *context __attribute__((unused)) )
 260 {
 261   return 0;
 262 }
 263
 264 _Unwind_Ptr
 265 _Unwind_GetTextRelBase (struct _Unwind_Context *context __attribute__((unused)) )
 266 {
 267   return 0;
 268 }
 269 #endif
 270 \f
 271 static inline _Unwind_Reason_Code
 272 uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
 273 {
 274   if (context->fc == NULL)
 275     {
 276       fs->personality = NULL;
 277       return _URC_END_OF_STACK;
 278     }
 279   else
 280     {
 281       fs->personality = context->fc->personality;
 282       return _URC_NO_REASON;
 283     }
 284 }
 285
 286 static inline void
 287 uw_update_context (struct _Unwind_Context *context,
 288                    _Unwind_FrameState *fs __attribute__((unused)) )
 289 {
 290   context->fc = context->fc->prev;
 291 }
 292
 293 static void
 294 uw_advance_context (struct _Unwind_Context *context, _Unwind_FrameState *fs)
 295 {
 296   _Unwind_SjLj_Unregister (context->fc);
 297   uw_update_context (context, fs);
 298 }
 299
 300 static inline void
 301 uw_init_context (struct _Unwind_Context *context)
 302 {
 303   context->fc = _Unwind_SjLj_GetContext ();
 304 }
 305
 306 static void __attribute__((noreturn))
 307 uw_install_context (struct _Unwind_Context *current __attribute__((unused)),
 308                     struct _Unwind_Context *target)
 309 {
 310   _Unwind_SjLj_SetContext (target->fc);
 311   longjmp (target->fc->jbuf, 1);
 312 }
 313
 314 static inline _Unwind_Ptr
 315 uw_identify_context (struct _Unwind_Context *context)
 316 {
 317   return (_Unwind_Ptr) context->fc;
 318 }
 319
 320
 321 /* Play games with unwind symbols so that we can have call frame
 322    and sjlj symbols in the same shared library.  Not that you can
 323    use them simultaneously...  */
 324 #define _Unwind_RaiseException          _Unwind_SjLj_RaiseException
 325 #define _Unwind_ForcedUnwind            _Unwind_SjLj_ForcedUnwind
 326 #define _Unwind_Resume                  _Unwind_SjLj_Resume
 327 #define _Unwind_Resume_or_Rethrow       _Unwind_SjLj_Resume_or_Rethrow
 328
 329 #include "unwind.inc"
 330
 331 #endif /* USING_SJLJ_EXCEPTIONS */