1/* Exception handling and frame unwind runtime interface routines. -*- C -*- 2 Copyright (C) 2001-2022 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 unsigned long *frames_p) 41{ 42 _Unwind_Reason_Code code; 43 unsigned long frames = 1; 44 45 while (1) 46 { 47 _Unwind_FrameState fs; 48 int match_handler; 49 50 code = uw_frame_state_for (context, &fs); 51 52 /* Identify when we've reached the designated handler context. */ 53 match_handler = (uw_identify_context (context) == exc->private_2 54 ? _UA_HANDLER_FRAME : 0); 55 56 if (code != _URC_NO_REASON) 57 /* Some error encountered. Usually the unwinder doesn't 58 diagnose these and merely crashes. */ 59 return _URC_FATAL_PHASE2_ERROR; 60 61 /* Unwind successful. Run the personality routine, if any. */ 62 if (fs.personality) 63 { 64 code = (*fs.personality) (1, _UA_CLEANUP_PHASE | match_handler, 65 exc->exception_class, exc, context); 66 if (code == _URC_INSTALL_CONTEXT) 67 break; 68 if (code != _URC_CONTINUE_UNWIND) 69 return _URC_FATAL_PHASE2_ERROR; 70 } 71 72 /* Don't let us unwind past the handler context. */ 73 gcc_assert (!match_handler); 74 75 uw_update_context (context, &fs); 76 _Unwind_Frames_Increment (context, frames); 77 } 78 79 *frames_p = frames; 80 return code; 81} 82 83/* Raise an exception, passing along the given exception object. */ 84 85_Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE 86_Unwind_RaiseException(struct _Unwind_Exception *exc) 87{ 88 struct _Unwind_Context this_context, cur_context; 89 _Unwind_Reason_Code code; 90 unsigned long frames; 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, &frames); 137 if (code != _URC_INSTALL_CONTEXT) 138 return code; 139 140 uw_install_context (&this_context, &cur_context, frames); 141} 142 143 144/* Subroutine of _Unwind_ForcedUnwind also invoked from _Unwind_Resume. */ 145 146static _Unwind_Reason_Code 147_Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception *exc, 148 struct _Unwind_Context *context, 149 unsigned long *frames_p) 150{ 151 _Unwind_Stop_Fn stop = (_Unwind_Stop_Fn) (_Unwind_Ptr) exc->private_1; 152 void *stop_argument = (void *) (_Unwind_Ptr) exc->private_2; 153 _Unwind_Reason_Code code, stop_code; 154 unsigned long frames = 1; 155 156 while (1) 157 { 158 _Unwind_FrameState fs; 159 int action; 160 161 /* Set up fs to describe the FDE for the caller of cur_context. */ 162 code = uw_frame_state_for (context, &fs); 163 if (code != _URC_NO_REASON && code != _URC_END_OF_STACK 164 && code != _URC_NORMAL_STOP) 165 return _URC_FATAL_PHASE2_ERROR; 166 167 /* Unwind successful. */ 168 action = _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE; 169 if (code == _URC_END_OF_STACK || code == _URC_NORMAL_STOP) 170 action |= _UA_END_OF_STACK; 171 stop_code = (*stop) (1, action, exc->exception_class, exc, 172 context, stop_argument); 173 if (stop_code != _URC_NO_REASON) 174 return _URC_FATAL_PHASE2_ERROR; 175 176 /* Stop didn't want to do anything. Invoke the personality 177 handler, if applicable, to run cleanups. */ 178 if (code == _URC_END_OF_STACK) 179 break; 180 181 if (fs.personality) 182 { 183 code = (*fs.personality) (1, _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE, 184 exc->exception_class, exc, context); 185 if (code == _URC_INSTALL_CONTEXT) 186 break; 187 if (code != _URC_CONTINUE_UNWIND) 188 return _URC_FATAL_PHASE2_ERROR; 189 } 190 191 /* Update cur_context to describe the same frame as fs, and discard 192 the previous context if necessary. */ 193 uw_advance_context (context, &fs); 194 _Unwind_Frames_Increment (context, frames); 195 } 196 197 *frames_p = frames; 198 return code; 199} 200 201 202/* Raise an exception for forced unwinding. */ 203 204_Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE 205_Unwind_ForcedUnwind (struct _Unwind_Exception *exc, 206 _Unwind_Stop_Fn stop, void * stop_argument) 207{ 208 struct _Unwind_Context this_context, cur_context; 209 _Unwind_Reason_Code code; 210 unsigned long frames; 211 212 uw_init_context (&this_context); 213 cur_context = this_context; 214 215 exc->private_1 = (_Unwind_Ptr) stop; 216 exc->private_2 = (_Unwind_Ptr) stop_argument; 217 218 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context, &frames); 219 if (code != _URC_INSTALL_CONTEXT) 220 return code; 221 222 uw_install_context (&this_context, &cur_context, frames); 223} 224 225 226/* Resume propagation of an existing exception. This is used after 227 e.g. executing cleanup code, and not to implement rethrowing. */ 228 229void LIBGCC2_UNWIND_ATTRIBUTE 230_Unwind_Resume (struct _Unwind_Exception *exc) 231{ 232 struct _Unwind_Context this_context, cur_context; 233 _Unwind_Reason_Code code; 234 unsigned long frames; 235 236 uw_init_context (&this_context); 237 cur_context = this_context; 238 239 /* Choose between continuing to process _Unwind_RaiseException 240 or _Unwind_ForcedUnwind. */ 241 if (exc->private_1 == 0) 242 code = _Unwind_RaiseException_Phase2 (exc, &cur_context, &frames); 243 else 244 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context, &frames); 245 246 gcc_assert (code == _URC_INSTALL_CONTEXT); 247 248 uw_install_context (&this_context, &cur_context, frames); 249} 250 251 252/* Resume propagation of an FORCE_UNWIND exception, or to rethrow 253 a normal exception that was handled. */ 254 255_Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE 256_Unwind_Resume_or_Rethrow (struct _Unwind_Exception *exc) 257{ 258 struct _Unwind_Context this_context, cur_context; 259 _Unwind_Reason_Code code; 260 unsigned long frames; 261 262 /* Choose between continuing to process _Unwind_RaiseException 263 or _Unwind_ForcedUnwind. */ 264 if (exc->private_1 == 0) 265 return _Unwind_RaiseException (exc); 266 267 uw_init_context (&this_context); 268 cur_context = this_context; 269 270 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context, &frames); 271 272 gcc_assert (code == _URC_INSTALL_CONTEXT); 273 274 uw_install_context (&this_context, &cur_context, frames); 275} 276 277 278/* A convenience function that calls the exception_cleanup field. */ 279 280void 281_Unwind_DeleteException (struct _Unwind_Exception *exc) 282{ 283 if (exc->exception_cleanup) 284 (*exc->exception_cleanup) (_URC_FOREIGN_EXCEPTION_CAUGHT, exc); 285} 286 287 288/* Perform stack backtrace through unwind data. */ 289 290_Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE 291_Unwind_Backtrace(_Unwind_Trace_Fn trace, void * trace_argument) 292{ 293 struct _Unwind_Context context; 294 _Unwind_Reason_Code code; 295 296 uw_init_context (&context); 297 298 while (1) 299 { 300 _Unwind_FrameState fs; 301 302 /* Set up fs to describe the FDE for the caller of context. */ 303 code = uw_frame_state_for (&context, &fs); 304 if (code != _URC_NO_REASON && code != _URC_END_OF_STACK 305 && code != _URC_NORMAL_STOP) 306 return _URC_FATAL_PHASE1_ERROR; 307 308 /* Call trace function. */ 309 if ((*trace) (&context, trace_argument) != _URC_NO_REASON) 310 return _URC_FATAL_PHASE1_ERROR; 311 312#ifdef MD_BACKCHAIN_FALLBACK 313 /* Do a backchain if there is no DWARF data. */ 314 if (code == _URC_NORMAL_STOP) 315 { 316 MD_BACKCHAIN_FALLBACK(&context, trace_argument); 317 break; 318 } 319#endif 320 321 /* We're done at end of stack. */ 322 if (code == _URC_END_OF_STACK) 323 break; 324 325 /* Update context to describe the same frame as fs. */ 326 uw_update_context (&context, &fs); 327 } 328 329 return code; 330} 331