gcc/unwind.inc

   1 /* Exception handling and frame unwind runtime interface routines. -*- C -*-
   2    Copyright (C) 2001, 2003, 2008 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    In addition to the permissions in the GNU General Public License, the
  12    Free Software Foundation gives you unlimited permission to link the
  13    compiled version of this file into combinations with other programs,
  14    and to distribute those combinations without any restriction coming
  15    from the use of this file.  (The General Public License restrictions
  16    do apply in other respects; for example, they cover modification of
  17    the file, and distribution when not linked into a combined
  18    executable.)
  19
  20    GCC is distributed in the hope that it will be useful, but WITHOUT
  21    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  22    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  23    License for more details.
  24
  25    You should have received a copy of the GNU General Public License
  26    along with GCC; see the file COPYING.  If not, write to the Free
  27    Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  28    02110-1301, USA.  */
  29
  30 /* This is derived from the C++ ABI for IA-64.  Where we diverge
  31    for cross-architecture compatibility are noted with "@@@".
  32    This file is included from unwind-dw2.c, unwind-sjlj.c or
  33    unwind-ia64.c.  */
  34
  35 /* Subroutine of _Unwind_RaiseException also invoked from _Unwind_Resume.
  36
  37    Unwind the stack calling the personality routine to find both the
  38    exception handler and intermediary cleanup code.  We'll only locate
  39    the first such frame here.  Cleanup code will call back into
  40    _Unwind_Resume and we'll continue Phase 2 there.  */
  41
  42 static _Unwind_Reason_Code
  43 _Unwind_RaiseException_Phase2(struct _Unwind_Exception *exc,
  44                               struct _Unwind_Context *context)
  45 {
  46   _Unwind_Reason_Code code;
  47
  48   while (1)
  49     {
  50       _Unwind_FrameState fs;
  51       int match_handler;
  52
  53       code = uw_frame_state_for (context, &fs);
  54
  55       /* Identify when we've reached the designated handler context.  */
  56       match_handler = (uw_identify_context (context) == exc->private_2
  57                        ? _UA_HANDLER_FRAME : 0);
  58
  59       if (code != _URC_NO_REASON)
  60         /* Some error encountered.  Usually the unwinder doesn't
  61            diagnose these and merely crashes.  */
  62         return _URC_FATAL_PHASE2_ERROR;
  63
  64       /* Unwind successful.  Run the personality routine, if any.  */
  65       if (fs.personality)
  66         {
  67           code = (*fs.personality) (1, _UA_CLEANUP_PHASE | match_handler,
  68                                     exc->exception_class, exc, context);
  69           if (code == _URC_INSTALL_CONTEXT)
  70             break;
  71           if (code != _URC_CONTINUE_UNWIND)
  72             return _URC_FATAL_PHASE2_ERROR;
  73         }
  74
  75       /* Don't let us unwind past the handler context.  */
  76       gcc_assert (!match_handler);
  77
  78       uw_update_context (context, &fs);
  79     }
  80
  81   return code;
  82 }
  83
  84 /* Raise an exception, passing along the given exception object.  */
  85
  86 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
  87 _Unwind_RaiseException(struct _Unwind_Exception *exc)
  88 {
  89   struct _Unwind_Context this_context, cur_context;
  90   _Unwind_Reason_Code code;
  91
  92   /* Set up this_context to describe the current stack frame.  */
  93   uw_init_context (&this_context);
  94   cur_context = this_context;
  95
  96   /* Phase 1: Search.  Unwind the stack, calling the personality routine
  97      with the _UA_SEARCH_PHASE flag set.  Do not modify the stack yet.  */
  98   while (1)
  99     {
 100       _Unwind_FrameState fs;
 101
 102       /* Set up fs to describe the FDE for the caller of cur_context.  The
 103          first time through the loop, that means __cxa_throw.  */
 104       code = uw_frame_state_for (&cur_context, &fs);
 105
 106       if (code == _URC_END_OF_STACK)
 107         /* Hit end of stack with no handler found.  */
 108         return _URC_END_OF_STACK;
 109
 110       if (code != _URC_NO_REASON)
 111         /* Some error encountered.  Usually the unwinder doesn't
 112            diagnose these and merely crashes.  */
 113         return _URC_FATAL_PHASE1_ERROR;
 114
 115       /* Unwind successful.  Run the personality routine, if any.  */
 116       if (fs.personality)
 117         {
 118           code = (*fs.personality) (1, _UA_SEARCH_PHASE, exc->exception_class,
 119                                     exc, &cur_context);
 120           if (code == _URC_HANDLER_FOUND)
 121             break;
 122           else if (code != _URC_CONTINUE_UNWIND)
 123             return _URC_FATAL_PHASE1_ERROR;
 124         }
 125
 126       /* Update cur_context to describe the same frame as fs.  */
 127       uw_update_context (&cur_context, &fs);
 128     }
 129
 130   /* Indicate to _Unwind_Resume and associated subroutines that this
 131      is not a forced unwind.  Further, note where we found a handler.  */
 132   exc->private_1 = 0;
 133   exc->private_2 = uw_identify_context (&cur_context);
 134
 135   cur_context = this_context;
 136   code = _Unwind_RaiseException_Phase2 (exc, &cur_context);
 137   if (code != _URC_INSTALL_CONTEXT)
 138     return code;
 139
 140   uw_install_context (&this_context, &cur_context);
 141 }
 142
 143
 144 /* Subroutine of _Unwind_ForcedUnwind also invoked from _Unwind_Resume.  */
 145
 146 static _Unwind_Reason_Code
 147 _Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception *exc,
 148                              struct _Unwind_Context *context)
 149 {
 150   _Unwind_Stop_Fn stop = (_Unwind_Stop_Fn) (_Unwind_Ptr) exc->private_1;
 151   void *stop_argument = (void *) (_Unwind_Ptr) exc->private_2;
 152   _Unwind_Reason_Code code, stop_code;
 153
 154   while (1)
 155     {
 156       _Unwind_FrameState fs;
 157       int action;
 158
 159       /* Set up fs to describe the FDE for the caller of cur_context.  */
 160       code = uw_frame_state_for (context, &fs);
 161       if (code != _URC_NO_REASON && code != _URC_END_OF_STACK)
 162         return _URC_FATAL_PHASE2_ERROR;
 163
 164       /* Unwind successful.  */
 165       action = _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE;
 166       if (code == _URC_END_OF_STACK)
 167         action |= _UA_END_OF_STACK;
 168       stop_code = (*stop) (1, action, exc->exception_class, exc,
 169                            context, stop_argument);
 170       if (stop_code != _URC_NO_REASON)
 171         return _URC_FATAL_PHASE2_ERROR;
 172
 173       /* Stop didn't want to do anything.  Invoke the personality
 174          handler, if applicable, to run cleanups.  */
 175       if (code == _URC_END_OF_STACK)
 176         break;
 177
 178       if (fs.personality)
 179         {
 180           code = (*fs.personality) (1, _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE,
 181                                     exc->exception_class, exc, context);
 182           if (code == _URC_INSTALL_CONTEXT)
 183             break;
 184           if (code != _URC_CONTINUE_UNWIND)
 185             return _URC_FATAL_PHASE2_ERROR;
 186         }
 187
 188       /* Update cur_context to describe the same frame as fs, and discard
 189          the previous context if necessary.  */
 190       uw_advance_context (context, &fs);
 191     }
 192
 193   return code;
 194 }
 195
 196
 197 /* Raise an exception for forced unwinding.  */
 198
 199 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
 200 _Unwind_ForcedUnwind (struct _Unwind_Exception *exc,
 201                       _Unwind_Stop_Fn stop, void * stop_argument)
 202 {
 203   struct _Unwind_Context this_context, cur_context;
 204   _Unwind_Reason_Code code;
 205
 206   uw_init_context (&this_context);
 207   cur_context = this_context;
 208
 209   exc->private_1 = (_Unwind_Ptr) stop;
 210   exc->private_2 = (_Unwind_Ptr) stop_argument;
 211
 212   code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
 213   if (code != _URC_INSTALL_CONTEXT)
 214     return code;
 215
 216   uw_install_context (&this_context, &cur_context);
 217 }
 218
 219
 220 /* Resume propagation of an existing exception.  This is used after
 221    e.g. executing cleanup code, and not to implement rethrowing.  */
 222
 223 void LIBGCC2_UNWIND_ATTRIBUTE
 224 _Unwind_Resume (struct _Unwind_Exception *exc)
 225 {
 226   struct _Unwind_Context this_context, cur_context;
 227   _Unwind_Reason_Code code;
 228
 229   uw_init_context (&this_context);
 230   cur_context = this_context;
 231
 232   /* Choose between continuing to process _Unwind_RaiseException
 233      or _Unwind_ForcedUnwind.  */
 234   if (exc->private_1 == 0)
 235     code = _Unwind_RaiseException_Phase2 (exc, &cur_context);
 236   else
 237     code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
 238
 239   gcc_assert (code == _URC_INSTALL_CONTEXT);
 240
 241   uw_install_context (&this_context, &cur_context);
 242 }
 243
 244
 245 /* Resume propagation of an FORCE_UNWIND exception, or to rethrow
 246    a normal exception that was handled.  */
 247
 248 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
 249 _Unwind_Resume_or_Rethrow (struct _Unwind_Exception *exc)
 250 {
 251   struct _Unwind_Context this_context, cur_context;
 252   _Unwind_Reason_Code code;
 253
 254   /* Choose between continuing to process _Unwind_RaiseException
 255      or _Unwind_ForcedUnwind.  */
 256   if (exc->private_1 == 0)
 257     return _Unwind_RaiseException (exc);
 258
 259   uw_init_context (&this_context);
 260   cur_context = this_context;
 261
 262   code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
 263
 264   gcc_assert (code == _URC_INSTALL_CONTEXT);
 265
 266   uw_install_context (&this_context, &cur_context);
 267 }
 268
 269
 270 /* A convenience function that calls the exception_cleanup field.  */
 271
 272 void
 273 _Unwind_DeleteException (struct _Unwind_Exception *exc)
 274 {
 275   if (exc->exception_cleanup)
 276     (*exc->exception_cleanup) (_URC_FOREIGN_EXCEPTION_CAUGHT, exc);
 277 }
 278
 279
 280 /* Perform stack backtrace through unwind data.  */
 281
 282 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
 283 _Unwind_Backtrace(_Unwind_Trace_Fn trace, void * trace_argument)
 284 {
 285   struct _Unwind_Context context;
 286   _Unwind_Reason_Code code;
 287
 288   uw_init_context (&context);
 289
 290   while (1)
 291     {
 292       _Unwind_FrameState fs;
 293
 294       /* Set up fs to describe the FDE for the caller of context.  */
 295       code = uw_frame_state_for (&context, &fs);
 296       if (code != _URC_NO_REASON && code != _URC_END_OF_STACK)
 297         return _URC_FATAL_PHASE1_ERROR;
 298
 299       /* Call trace function.  */
 300       if ((*trace) (&context, trace_argument) != _URC_NO_REASON)
 301         return _URC_FATAL_PHASE1_ERROR;
 302
 303       /* We're done at end of stack.  */
 304       if (code == _URC_END_OF_STACK)
 305         break;
 306
 307       /* Update context to describe the same frame as fs.  */
 308       uw_update_context (&context, &fs);
 309     }
 310
 311   return code;
 312 }