1 //===------------------------- UnwindLevel1.c -----------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 // 8 // Implements C++ ABI Exception Handling Level 1 as documented at: 9 // https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html 10 // using libunwind 11 // 12 //===----------------------------------------------------------------------===// 13 14 // ARM EHABI does not specify _Unwind_{Get,Set}{GR,IP}(). Thus, we are 15 // defining inline functions to delegate the function calls to 16 // _Unwind_VRS_{Get,Set}(). However, some applications might declare the 17 // function protetype directly (instead of including <unwind.h>), thus we need 18 // to export these functions from libunwind.so as well. 19 #define _LIBUNWIND_UNWIND_LEVEL1_EXTERNAL_LINKAGE 1 20 21 #include <inttypes.h> 22 #include <stdint.h> 23 #include <stdbool.h> 24 #include <stdlib.h> 25 #include <stdio.h> 26 #include <string.h> 27 28 #include "config.h" 29 #include "libunwind.h" 30 #include "libunwind_ext.h" 31 #include "unwind.h" 32 33 #if !defined(_LIBUNWIND_ARM_EHABI) && !defined(__USING_SJLJ_EXCEPTIONS__) 34 35 #ifndef _LIBUNWIND_SUPPORT_SEH_UNWIND 36 37 static _Unwind_Reason_Code 38 unwind_phase1(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *exception_object) { 39 __unw_init_local(cursor, uc); 40 41 // Walk each frame looking for a place to stop. 42 bool handlerNotFound = true; 43 while (handlerNotFound) { 44 // Ask libunwind to get next frame (skip over first which is 45 // _Unwind_RaiseException). 46 int stepResult = __unw_step(cursor); 47 if (stepResult == 0) { 48 _LIBUNWIND_TRACE_UNWINDING( 49 "unwind_phase1(ex_ojb=%p): __unw_step() reached " 50 "bottom => _URC_END_OF_STACK", 51 (void *)exception_object); 52 return _URC_END_OF_STACK; 53 } else if (stepResult < 0) { 54 _LIBUNWIND_TRACE_UNWINDING( 55 "unwind_phase1(ex_ojb=%p): __unw_step failed => " 56 "_URC_FATAL_PHASE1_ERROR", 57 (void *)exception_object); 58 return _URC_FATAL_PHASE1_ERROR; 59 } 60 61 // See if frame has code to run (has personality routine). 62 unw_proc_info_t frameInfo; 63 unw_word_t sp; 64 if (__unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) { 65 _LIBUNWIND_TRACE_UNWINDING( 66 "unwind_phase1(ex_ojb=%p): __unw_get_proc_info " 67 "failed => _URC_FATAL_PHASE1_ERROR", 68 (void *)exception_object); 69 return _URC_FATAL_PHASE1_ERROR; 70 } 71 72 // When tracing, print state information. 73 if (_LIBUNWIND_TRACING_UNWINDING) { 74 char functionBuf[512]; 75 const char *functionName = functionBuf; 76 unw_word_t offset; 77 if ((__unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf), 78 &offset) != UNW_ESUCCESS) || 79 (frameInfo.start_ip + offset > frameInfo.end_ip)) 80 functionName = ".anonymous."; 81 unw_word_t pc; 82 __unw_get_reg(cursor, UNW_REG_IP, &pc); 83 _LIBUNWIND_TRACE_UNWINDING( 84 "unwind_phase1(ex_ojb=%p): pc=0x%" PRIxPTR ", start_ip=0x%" PRIxPTR 85 ", func=%s, lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR "", 86 (void *)exception_object, pc, frameInfo.start_ip, functionName, 87 frameInfo.lsda, frameInfo.handler); 88 } 89 90 // If there is a personality routine, ask it if it will want to stop at 91 // this frame. 92 if (frameInfo.handler != 0) { 93 _Unwind_Personality_Fn p = 94 (_Unwind_Personality_Fn)(uintptr_t)(frameInfo.handler); 95 _LIBUNWIND_TRACE_UNWINDING( 96 "unwind_phase1(ex_ojb=%p): calling personality function %p", 97 (void *)exception_object, (void *)(uintptr_t)p); 98 _Unwind_Reason_Code personalityResult = 99 (*p)(1, _UA_SEARCH_PHASE, exception_object->exception_class, 100 exception_object, (struct _Unwind_Context *)(cursor)); 101 switch (personalityResult) { 102 case _URC_HANDLER_FOUND: 103 // found a catch clause or locals that need destructing in this frame 104 // stop search and remember stack pointer at the frame 105 handlerNotFound = false; 106 __unw_get_reg(cursor, UNW_REG_SP, &sp); 107 exception_object->private_2 = (uintptr_t)sp; 108 _LIBUNWIND_TRACE_UNWINDING( 109 "unwind_phase1(ex_ojb=%p): _URC_HANDLER_FOUND", 110 (void *)exception_object); 111 return _URC_NO_REASON; 112 113 case _URC_CONTINUE_UNWIND: 114 _LIBUNWIND_TRACE_UNWINDING( 115 "unwind_phase1(ex_ojb=%p): _URC_CONTINUE_UNWIND", 116 (void *)exception_object); 117 // continue unwinding 118 break; 119 120 default: 121 // something went wrong 122 _LIBUNWIND_TRACE_UNWINDING( 123 "unwind_phase1(ex_ojb=%p): _URC_FATAL_PHASE1_ERROR", 124 (void *)exception_object); 125 return _URC_FATAL_PHASE1_ERROR; 126 } 127 } 128 } 129 return _URC_NO_REASON; 130 } 131 132 133 static _Unwind_Reason_Code 134 unwind_phase2(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *exception_object) { 135 __unw_init_local(cursor, uc); 136 137 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p)", 138 (void *)exception_object); 139 140 // Walk each frame until we reach where search phase said to stop. 141 while (true) { 142 143 // Ask libunwind to get next frame (skip over first which is 144 // _Unwind_RaiseException). 145 int stepResult = __unw_step(cursor); 146 if (stepResult == 0) { 147 _LIBUNWIND_TRACE_UNWINDING( 148 "unwind_phase2(ex_ojb=%p): __unw_step() reached " 149 "bottom => _URC_END_OF_STACK", 150 (void *)exception_object); 151 return _URC_END_OF_STACK; 152 } else if (stepResult < 0) { 153 _LIBUNWIND_TRACE_UNWINDING( 154 "unwind_phase2(ex_ojb=%p): __unw_step failed => " 155 "_URC_FATAL_PHASE1_ERROR", 156 (void *)exception_object); 157 return _URC_FATAL_PHASE2_ERROR; 158 } 159 160 // Get info about this frame. 161 unw_word_t sp; 162 unw_proc_info_t frameInfo; 163 __unw_get_reg(cursor, UNW_REG_SP, &sp); 164 if (__unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) { 165 _LIBUNWIND_TRACE_UNWINDING( 166 "unwind_phase2(ex_ojb=%p): __unw_get_proc_info " 167 "failed => _URC_FATAL_PHASE1_ERROR", 168 (void *)exception_object); 169 return _URC_FATAL_PHASE2_ERROR; 170 } 171 172 // When tracing, print state information. 173 if (_LIBUNWIND_TRACING_UNWINDING) { 174 char functionBuf[512]; 175 const char *functionName = functionBuf; 176 unw_word_t offset; 177 if ((__unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf), 178 &offset) != UNW_ESUCCESS) || 179 (frameInfo.start_ip + offset > frameInfo.end_ip)) 180 functionName = ".anonymous."; 181 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): start_ip=0x%" PRIxPTR 182 ", func=%s, sp=0x%" PRIxPTR ", lsda=0x%" PRIxPTR 183 ", personality=0x%" PRIxPTR, 184 (void *)exception_object, frameInfo.start_ip, 185 functionName, sp, frameInfo.lsda, 186 frameInfo.handler); 187 } 188 189 // If there is a personality routine, tell it we are unwinding. 190 if (frameInfo.handler != 0) { 191 _Unwind_Personality_Fn p = 192 (_Unwind_Personality_Fn)(uintptr_t)(frameInfo.handler); 193 _Unwind_Action action = _UA_CLEANUP_PHASE; 194 if (sp == exception_object->private_2) { 195 // Tell personality this was the frame it marked in phase 1. 196 action = (_Unwind_Action)(_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME); 197 } 198 _Unwind_Reason_Code personalityResult = 199 (*p)(1, action, exception_object->exception_class, exception_object, 200 (struct _Unwind_Context *)(cursor)); 201 switch (personalityResult) { 202 case _URC_CONTINUE_UNWIND: 203 // Continue unwinding 204 _LIBUNWIND_TRACE_UNWINDING( 205 "unwind_phase2(ex_ojb=%p): _URC_CONTINUE_UNWIND", 206 (void *)exception_object); 207 if (sp == exception_object->private_2) { 208 // Phase 1 said we would stop at this frame, but we did not... 209 _LIBUNWIND_ABORT("during phase1 personality function said it would " 210 "stop here, but now in phase2 it did not stop here"); 211 } 212 break; 213 case _URC_INSTALL_CONTEXT: 214 _LIBUNWIND_TRACE_UNWINDING( 215 "unwind_phase2(ex_ojb=%p): _URC_INSTALL_CONTEXT", 216 (void *)exception_object); 217 // Personality routine says to transfer control to landing pad. 218 // We may get control back if landing pad calls _Unwind_Resume(). 219 if (_LIBUNWIND_TRACING_UNWINDING) { 220 unw_word_t pc; 221 __unw_get_reg(cursor, UNW_REG_IP, &pc); 222 __unw_get_reg(cursor, UNW_REG_SP, &sp); 223 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): re-entering " 224 "user code with ip=0x%" PRIxPTR 225 ", sp=0x%" PRIxPTR, 226 (void *)exception_object, pc, sp); 227 } 228 __unw_resume(cursor); 229 // __unw_resume() only returns if there was an error. 230 return _URC_FATAL_PHASE2_ERROR; 231 default: 232 // Personality routine returned an unknown result code. 233 _LIBUNWIND_DEBUG_LOG("personality function returned unknown result %d", 234 personalityResult); 235 return _URC_FATAL_PHASE2_ERROR; 236 } 237 } 238 } 239 240 // Clean up phase did not resume at the frame that the search phase 241 // said it would... 242 return _URC_FATAL_PHASE2_ERROR; 243 } 244 245 static _Unwind_Reason_Code 246 unwind_phase2_forced(unw_context_t *uc, unw_cursor_t *cursor, 247 _Unwind_Exception *exception_object, 248 _Unwind_Stop_Fn stop, void *stop_parameter) { 249 __unw_init_local(cursor, uc); 250 251 // Walk each frame until we reach where search phase said to stop 252 while (__unw_step(cursor) > 0) { 253 254 // Update info about this frame. 255 unw_proc_info_t frameInfo; 256 if (__unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) { 257 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): __unw_step " 258 "failed => _URC_END_OF_STACK", 259 (void *)exception_object); 260 return _URC_FATAL_PHASE2_ERROR; 261 } 262 263 // When tracing, print state information. 264 if (_LIBUNWIND_TRACING_UNWINDING) { 265 char functionBuf[512]; 266 const char *functionName = functionBuf; 267 unw_word_t offset; 268 if ((__unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf), 269 &offset) != UNW_ESUCCESS) || 270 (frameInfo.start_ip + offset > frameInfo.end_ip)) 271 functionName = ".anonymous."; 272 _LIBUNWIND_TRACE_UNWINDING( 273 "unwind_phase2_forced(ex_ojb=%p): start_ip=0x%" PRIxPTR 274 ", func=%s, lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR, 275 (void *)exception_object, frameInfo.start_ip, functionName, 276 frameInfo.lsda, frameInfo.handler); 277 } 278 279 // Call stop function at each frame. 280 _Unwind_Action action = 281 (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE); 282 _Unwind_Reason_Code stopResult = 283 (*stop)(1, action, exception_object->exception_class, exception_object, 284 (struct _Unwind_Context *)(cursor), stop_parameter); 285 _LIBUNWIND_TRACE_UNWINDING( 286 "unwind_phase2_forced(ex_ojb=%p): stop function returned %d", 287 (void *)exception_object, stopResult); 288 if (stopResult != _URC_NO_REASON) { 289 _LIBUNWIND_TRACE_UNWINDING( 290 "unwind_phase2_forced(ex_ojb=%p): stopped by stop function", 291 (void *)exception_object); 292 return _URC_FATAL_PHASE2_ERROR; 293 } 294 295 // If there is a personality routine, tell it we are unwinding. 296 if (frameInfo.handler != 0) { 297 _Unwind_Personality_Fn p = 298 (_Unwind_Personality_Fn)(intptr_t)(frameInfo.handler); 299 _LIBUNWIND_TRACE_UNWINDING( 300 "unwind_phase2_forced(ex_ojb=%p): calling personality function %p", 301 (void *)exception_object, (void *)(uintptr_t)p); 302 _Unwind_Reason_Code personalityResult = 303 (*p)(1, action, exception_object->exception_class, exception_object, 304 (struct _Unwind_Context *)(cursor)); 305 switch (personalityResult) { 306 case _URC_CONTINUE_UNWIND: 307 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): " 308 "personality returned " 309 "_URC_CONTINUE_UNWIND", 310 (void *)exception_object); 311 // Destructors called, continue unwinding 312 break; 313 case _URC_INSTALL_CONTEXT: 314 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): " 315 "personality returned " 316 "_URC_INSTALL_CONTEXT", 317 (void *)exception_object); 318 // We may get control back if landing pad calls _Unwind_Resume(). 319 __unw_resume(cursor); 320 break; 321 default: 322 // Personality routine returned an unknown result code. 323 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): " 324 "personality returned %d, " 325 "_URC_FATAL_PHASE2_ERROR", 326 (void *)exception_object, personalityResult); 327 return _URC_FATAL_PHASE2_ERROR; 328 } 329 } 330 } 331 332 // Call stop function one last time and tell it we've reached the end 333 // of the stack. 334 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): calling stop " 335 "function with _UA_END_OF_STACK", 336 (void *)exception_object); 337 _Unwind_Action lastAction = 338 (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE | _UA_END_OF_STACK); 339 (*stop)(1, lastAction, exception_object->exception_class, exception_object, 340 (struct _Unwind_Context *)(cursor), stop_parameter); 341 342 // Clean up phase did not resume at the frame that the search phase said it 343 // would. 344 return _URC_FATAL_PHASE2_ERROR; 345 } 346 347 348 /// Called by __cxa_throw. Only returns if there is a fatal error. 349 _LIBUNWIND_EXPORT _Unwind_Reason_Code 350 _Unwind_RaiseException(_Unwind_Exception *exception_object) { 351 _LIBUNWIND_TRACE_API("_Unwind_RaiseException(ex_obj=%p)", 352 (void *)exception_object); 353 unw_context_t uc; 354 unw_cursor_t cursor; 355 __unw_getcontext(&uc); 356 357 // Mark that this is a non-forced unwind, so _Unwind_Resume() 358 // can do the right thing. 359 exception_object->private_1 = 0; 360 exception_object->private_2 = 0; 361 362 // phase 1: the search phase 363 _Unwind_Reason_Code phase1 = unwind_phase1(&uc, &cursor, exception_object); 364 if (phase1 != _URC_NO_REASON) 365 return phase1; 366 367 // phase 2: the clean up phase 368 return unwind_phase2(&uc, &cursor, exception_object); 369 } 370 371 372 373 /// When _Unwind_RaiseException() is in phase2, it hands control 374 /// to the personality function at each frame. The personality 375 /// may force a jump to a landing pad in that function, the landing 376 /// pad code may then call _Unwind_Resume() to continue with the 377 /// unwinding. Note: the call to _Unwind_Resume() is from compiler 378 /// geneated user code. All other _Unwind_* routines are called 379 /// by the C++ runtime __cxa_* routines. 380 /// 381 /// Note: re-throwing an exception (as opposed to continuing the unwind) 382 /// is implemented by having the code call __cxa_rethrow() which 383 /// in turn calls _Unwind_Resume_or_Rethrow(). 384 _LIBUNWIND_EXPORT void 385 _Unwind_Resume(_Unwind_Exception *exception_object) { 386 _LIBUNWIND_TRACE_API("_Unwind_Resume(ex_obj=%p)", (void *)exception_object); 387 unw_context_t uc; 388 unw_cursor_t cursor; 389 __unw_getcontext(&uc); 390 391 if (exception_object->private_1 != 0) 392 unwind_phase2_forced(&uc, &cursor, exception_object, 393 (_Unwind_Stop_Fn) exception_object->private_1, 394 (void *)exception_object->private_2); 395 else 396 unwind_phase2(&uc, &cursor, exception_object); 397 398 // Clients assume _Unwind_Resume() does not return, so all we can do is abort. 399 _LIBUNWIND_ABORT("_Unwind_Resume() can't return"); 400 } 401 402 403 404 /// Not used by C++. 405 /// Unwinds stack, calling "stop" function at each frame. 406 /// Could be used to implement longjmp(). 407 _LIBUNWIND_EXPORT _Unwind_Reason_Code 408 _Unwind_ForcedUnwind(_Unwind_Exception *exception_object, 409 _Unwind_Stop_Fn stop, void *stop_parameter) { 410 _LIBUNWIND_TRACE_API("_Unwind_ForcedUnwind(ex_obj=%p, stop=%p)", 411 (void *)exception_object, (void *)(uintptr_t)stop); 412 unw_context_t uc; 413 unw_cursor_t cursor; 414 __unw_getcontext(&uc); 415 416 // Mark that this is a forced unwind, so _Unwind_Resume() can do 417 // the right thing. 418 exception_object->private_1 = (uintptr_t) stop; 419 exception_object->private_2 = (uintptr_t) stop_parameter; 420 421 // do it 422 return unwind_phase2_forced(&uc, &cursor, exception_object, stop, stop_parameter); 423 } 424 425 426 /// Called by personality handler during phase 2 to get LSDA for current frame. 427 _LIBUNWIND_EXPORT uintptr_t 428 _Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) { 429 unw_cursor_t *cursor = (unw_cursor_t *)context; 430 unw_proc_info_t frameInfo; 431 uintptr_t result = 0; 432 if (__unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS) 433 result = (uintptr_t)frameInfo.lsda; 434 _LIBUNWIND_TRACE_API( 435 "_Unwind_GetLanguageSpecificData(context=%p) => 0x%" PRIxPTR, 436 (void *)context, result); 437 if (result != 0) { 438 if (*((uint8_t *)result) != 0xFF) 439 _LIBUNWIND_DEBUG_LOG("lsda at 0x%" PRIxPTR " does not start with 0xFF", 440 result); 441 } 442 return result; 443 } 444 445 446 /// Called by personality handler during phase 2 to find the start of the 447 /// function. 448 _LIBUNWIND_EXPORT uintptr_t 449 _Unwind_GetRegionStart(struct _Unwind_Context *context) { 450 unw_cursor_t *cursor = (unw_cursor_t *)context; 451 unw_proc_info_t frameInfo; 452 uintptr_t result = 0; 453 if (__unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS) 454 result = (uintptr_t)frameInfo.start_ip; 455 _LIBUNWIND_TRACE_API("_Unwind_GetRegionStart(context=%p) => 0x%" PRIxPTR, 456 (void *)context, result); 457 return result; 458 } 459 460 #endif // !_LIBUNWIND_SUPPORT_SEH_UNWIND 461 462 /// Called by personality handler during phase 2 if a foreign exception 463 // is caught. 464 _LIBUNWIND_EXPORT void 465 _Unwind_DeleteException(_Unwind_Exception *exception_object) { 466 _LIBUNWIND_TRACE_API("_Unwind_DeleteException(ex_obj=%p)", 467 (void *)exception_object); 468 if (exception_object->exception_cleanup != NULL) 469 (*exception_object->exception_cleanup)(_URC_FOREIGN_EXCEPTION_CAUGHT, 470 exception_object); 471 } 472 473 /// Called by personality handler during phase 2 to get register values. 474 _LIBUNWIND_EXPORT uintptr_t 475 _Unwind_GetGR(struct _Unwind_Context *context, int index) { 476 unw_cursor_t *cursor = (unw_cursor_t *)context; 477 unw_word_t result; 478 __unw_get_reg(cursor, index, &result); 479 _LIBUNWIND_TRACE_API("_Unwind_GetGR(context=%p, reg=%d) => 0x%" PRIxPTR, 480 (void *)context, index, result); 481 return (uintptr_t)result; 482 } 483 484 /// Called by personality handler during phase 2 to alter register values. 485 _LIBUNWIND_EXPORT void _Unwind_SetGR(struct _Unwind_Context *context, int index, 486 uintptr_t value) { 487 _LIBUNWIND_TRACE_API("_Unwind_SetGR(context=%p, reg=%d, value=0x%0" PRIxPTR 488 ")", 489 (void *)context, index, value); 490 unw_cursor_t *cursor = (unw_cursor_t *)context; 491 __unw_set_reg(cursor, index, value); 492 } 493 494 /// Called by personality handler during phase 2 to get instruction pointer. 495 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIP(struct _Unwind_Context *context) { 496 unw_cursor_t *cursor = (unw_cursor_t *)context; 497 unw_word_t result; 498 __unw_get_reg(cursor, UNW_REG_IP, &result); 499 _LIBUNWIND_TRACE_API("_Unwind_GetIP(context=%p) => 0x%" PRIxPTR, 500 (void *)context, result); 501 return (uintptr_t)result; 502 } 503 504 /// Called by personality handler during phase 2 to alter instruction pointer, 505 /// such as setting where the landing pad is, so _Unwind_Resume() will 506 /// start executing in the landing pad. 507 _LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *context, 508 uintptr_t value) { 509 _LIBUNWIND_TRACE_API("_Unwind_SetIP(context=%p, value=0x%0" PRIxPTR ")", 510 (void *)context, value); 511 unw_cursor_t *cursor = (unw_cursor_t *)context; 512 __unw_set_reg(cursor, UNW_REG_IP, value); 513 } 514 515 #endif // !defined(_LIBUNWIND_ARM_EHABI) && !defined(__USING_SJLJ_EXCEPTIONS__) 516