1/* Exception handling and frame unwind runtime interface routines. -*- C -*- 2 Copyright (C) 2001, 2003, 2008, 2009 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 3, 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 Under Section 7 of GPL version 3, you are granted additional 17 permissions described in the GCC Runtime Library Exception, version 18 3.1, as published by the Free Software Foundation. 19 20 You should have received a copy of the GNU General Public License and 21 a copy of the GCC Runtime Library Exception along with this program; 22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 <http://www.gnu.org/licenses/>. */ 24 25/* This is derived from the C++ ABI for IA-64. Where we diverge 26 for cross-architecture compatibility are noted with "@@@". 27 This file is included from unwind-dw2.c, unwind-sjlj.c or 28 unwind-ia64.c. */ 29 30/* Subroutine of _Unwind_RaiseException also invoked from _Unwind_Resume. 31 32 Unwind the stack calling the personality routine to find both the 33 exception handler and intermediary cleanup code. We'll only locate 34 the first such frame here. Cleanup code will call back into 35 _Unwind_Resume and we'll continue Phase 2 there. */ 36 37static _Unwind_Reason_Code 38_Unwind_RaiseException_Phase2(struct _Unwind_Exception *exc, 39 struct _Unwind_Context *context) 40{ 41 _Unwind_Reason_Code code; 42 43 while (1) 44 { 45 _Unwind_FrameState fs; 46 int match_handler; 47 48 code = uw_frame_state_for (context, &fs); 49 50 /* Identify when we've reached the designated handler context. */ 51 match_handler = (uw_identify_context (context) == exc->private_2 52 ? _UA_HANDLER_FRAME : 0); 53 54 if (code != _URC_NO_REASON) 55 /* Some error encountered. Usually the unwinder doesn't 56 diagnose these and merely crashes. */ 57 return _URC_FATAL_PHASE2_ERROR; 58 59 /* Unwind successful. Run the personality routine, if any. */ 60 if (fs.personality) 61 { 62 code = (*fs.personality) (1, _UA_CLEANUP_PHASE | match_handler, 63 exc->exception_class, exc, context); 64 if (code == _URC_INSTALL_CONTEXT) 65 break; 66 if (code != _URC_CONTINUE_UNWIND) 67 return _URC_FATAL_PHASE2_ERROR; 68 } 69 70 /* Don't let us unwind past the handler context. */ 71 gcc_assert (!match_handler); 72 73 uw_update_context (context, &fs); 74 } 75 76 return code; 77} 78 79/* Raise an exception, passing along the given exception object. */ 80 81_Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE 82_Unwind_RaiseException(struct _Unwind_Exception *exc) 83{ 84 struct _Unwind_Context this_context, cur_context; 85 _Unwind_Reason_Code code; 86 87 /* Set up this_context to describe the current stack frame. */ 88 uw_init_context (&this_context); 89 cur_context = this_context; 90 91 /* Phase 1: Search. Unwind the stack, calling the personality routine 92 with the _UA_SEARCH_PHASE flag set. Do not modify the stack yet. */ 93 while (1) 94 { 95 _Unwind_FrameState fs; 96 97 /* Set up fs to describe the FDE for the caller of cur_context. The 98 first time through the loop, that means __cxa_throw. */ 99 code = uw_frame_state_for (&cur_context, &fs); 100 101 if (code == _URC_END_OF_STACK) 102 /* Hit end of stack with no handler found. */ 103 return _URC_END_OF_STACK; 104 105 if (code != _URC_NO_REASON) 106 /* Some error encountered. Usually the unwinder doesn't 107 diagnose these and merely crashes. */ 108 return _URC_FATAL_PHASE1_ERROR; 109 110 /* Unwind successful. Run the personality routine, if any. */ 111 if (fs.personality) 112 { 113 code = (*fs.personality) (1, _UA_SEARCH_PHASE, exc->exception_class, 114 exc, &cur_context); 115 if (code == _URC_HANDLER_FOUND) 116 break; 117 else if (code != _URC_CONTINUE_UNWIND) 118 return _URC_FATAL_PHASE1_ERROR; 119 } 120 121 /* Update cur_context to describe the same frame as fs. */ 122 uw_update_context (&cur_context, &fs); 123 } 124 125 /* Indicate to _Unwind_Resume and associated subroutines that this 126 is not a forced unwind. Further, note where we found a handler. */ 127 exc->private_1 = 0; 128 exc->private_2 = uw_identify_context (&cur_context); 129 130 cur_context = this_context; 131 code = _Unwind_RaiseException_Phase2 (exc, &cur_context); 132 if (code != _URC_INSTALL_CONTEXT) 133 return code; 134 135 uw_install_context (&this_context, &cur_context); 136} 137 138 139/* Subroutine of _Unwind_ForcedUnwind also invoked from _Unwind_Resume. */ 140 141static _Unwind_Reason_Code 142_Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception *exc, 143 struct _Unwind_Context *context) 144{ 145 _Unwind_Stop_Fn stop = (_Unwind_Stop_Fn) (_Unwind_Ptr) exc->private_1; 146 void *stop_argument = (void *) (_Unwind_Ptr) exc->private_2; 147 _Unwind_Reason_Code code, stop_code; 148 149 while (1) 150 { 151 _Unwind_FrameState fs; 152 int action; 153 154 /* Set up fs to describe the FDE for the caller of cur_context. */ 155 code = uw_frame_state_for (context, &fs); 156 if (code != _URC_NO_REASON && code != _URC_END_OF_STACK) 157 return _URC_FATAL_PHASE2_ERROR; 158 159 /* Unwind successful. */ 160 action = _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE; 161 if (code == _URC_END_OF_STACK) 162 action |= _UA_END_OF_STACK; 163 stop_code = (*stop) (1, action, exc->exception_class, exc, 164 context, stop_argument); 165 if (stop_code != _URC_NO_REASON) 166 return _URC_FATAL_PHASE2_ERROR; 167 168 /* Stop didn't want to do anything. Invoke the personality 169 handler, if applicable, to run cleanups. */ 170 if (code == _URC_END_OF_STACK) 171 break; 172 173 if (fs.personality) 174 { 175 code = (*fs.personality) (1, _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE, 176 exc->exception_class, exc, context); 177 if (code == _URC_INSTALL_CONTEXT) 178 break; 179 if (code != _URC_CONTINUE_UNWIND) 180 return _URC_FATAL_PHASE2_ERROR; 181 } 182 183 /* Update cur_context to describe the same frame as fs, and discard 184 the previous context if necessary. */ 185 uw_advance_context (context, &fs); 186 } 187 188 return code; 189} 190 191 192/* Raise an exception for forced unwinding. */ 193 194_Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE 195_Unwind_ForcedUnwind (struct _Unwind_Exception *exc, 196 _Unwind_Stop_Fn stop, void * stop_argument) 197{ 198 struct _Unwind_Context this_context, cur_context; 199 _Unwind_Reason_Code code; 200 201 uw_init_context (&this_context); 202 cur_context = this_context; 203 204 exc->private_1 = (_Unwind_Ptr) stop; 205 exc->private_2 = (_Unwind_Ptr) stop_argument; 206 207 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context); 208 if (code != _URC_INSTALL_CONTEXT) 209 return code; 210 211 uw_install_context (&this_context, &cur_context); 212} 213 214 215/* Resume propagation of an existing exception. This is used after 216 e.g. executing cleanup code, and not to implement rethrowing. */ 217 218void LIBGCC2_UNWIND_ATTRIBUTE 219_Unwind_Resume (struct _Unwind_Exception *exc) 220{ 221 struct _Unwind_Context this_context, cur_context; 222 _Unwind_Reason_Code code; 223 224 uw_init_context (&this_context); 225 cur_context = this_context; 226 227 /* Choose between continuing to process _Unwind_RaiseException 228 or _Unwind_ForcedUnwind. */ 229 if (exc->private_1 == 0) 230 code = _Unwind_RaiseException_Phase2 (exc, &cur_context); 231 else 232 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context); 233 234 gcc_assert (code == _URC_INSTALL_CONTEXT); 235 236 uw_install_context (&this_context, &cur_context); 237} 238 239 240/* Resume propagation of an FORCE_UNWIND exception, or to rethrow 241 a normal exception that was handled. */ 242 243_Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE 244_Unwind_Resume_or_Rethrow (struct _Unwind_Exception *exc) 245{ 246 struct _Unwind_Context this_context, cur_context; 247 _Unwind_Reason_Code code; 248 249 /* Choose between continuing to process _Unwind_RaiseException 250 or _Unwind_ForcedUnwind. */ 251 if (exc->private_1 == 0) 252 return _Unwind_RaiseException (exc); 253 254 uw_init_context (&this_context); 255 cur_context = this_context; 256 257 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context); 258 259 gcc_assert (code == _URC_INSTALL_CONTEXT); 260 261 uw_install_context (&this_context, &cur_context); 262} 263 264 265/* A convenience function that calls the exception_cleanup field. */ 266 267void 268_Unwind_DeleteException (struct _Unwind_Exception *exc) 269{ 270 if (exc->exception_cleanup) 271 (*exc->exception_cleanup) (_URC_FOREIGN_EXCEPTION_CAUGHT, exc); 272} 273 274 275/* Perform stack backtrace through unwind data. */ 276 277_Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE 278_Unwind_Backtrace(_Unwind_Trace_Fn trace, void * trace_argument) 279{ 280 struct _Unwind_Context context; 281 _Unwind_Reason_Code code; 282 283 uw_init_context (&context); 284 285 while (1) 286 { 287 _Unwind_FrameState fs; 288 289 /* Set up fs to describe the FDE for the caller of context. */ 290 code = uw_frame_state_for (&context, &fs); 291 if (code != _URC_NO_REASON && code != _URC_END_OF_STACK) 292 return _URC_FATAL_PHASE1_ERROR; 293 294 /* Call trace function. */ 295 if ((*trace) (&context, trace_argument) != _URC_NO_REASON) 296 return _URC_FATAL_PHASE1_ERROR; 297 298 /* We're done at end of stack. */ 299 if (code == _URC_END_OF_STACK) 300 break; 301 302 /* Update context to describe the same frame as fs. */ 303 uw_update_context (&context, &fs); 304 } 305 306 return code; 307} 308