1 //===----------------------------------------------------------------------===// 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 // This file implements the "Exception Handling APIs" 9 // https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html 10 // http://www.intel.com/design/itanium/downloads/245358.htm 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include <assert.h> 15 #include <stdlib.h> 16 #include <string.h> 17 #include <typeinfo> 18 19 #include "__cxxabi_config.h" 20 #include "cxa_exception.h" 21 #include "cxa_handlers.h" 22 #include "private_typeinfo.h" 23 #include "unwind.h" 24 25 // TODO: This is a temporary workaround for libc++abi to recognize that it's being 26 // built against LLVM's libunwind. LLVM's libunwind started reporting _LIBUNWIND_VERSION 27 // in LLVM 15 -- we can remove this workaround after shipping LLVM 17. Once we remove 28 // this workaround, it won't be possible to build libc++abi against libunwind headers 29 // from LLVM 14 and before anymore. 30 #if defined(____LIBUNWIND_CONFIG_H__) && !defined(_LIBUNWIND_VERSION) 31 # define _LIBUNWIND_VERSION 32 #endif 33 34 #if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__) 35 #include <windows.h> 36 #include <winnt.h> 37 38 extern "C" EXCEPTION_DISPOSITION _GCC_specific_handler(PEXCEPTION_RECORD, 39 void *, PCONTEXT, 40 PDISPATCHER_CONTEXT, 41 _Unwind_Personality_Fn); 42 #endif 43 44 /* 45 Exception Header Layout: 46 47 +---------------------------+-----------------------------+---------------+ 48 | __cxa_exception | _Unwind_Exception CLNGC++\0 | thrown object | 49 +---------------------------+-----------------------------+---------------+ 50 ^ 51 | 52 +-------------------------------------------------------+ 53 | 54 +---------------------------+-----------------------------+ 55 | __cxa_dependent_exception | _Unwind_Exception CLNGC++\1 | 56 +---------------------------+-----------------------------+ 57 58 Exception Handling Table Layout: 59 60 +-----------------+--------+ 61 | lpStartEncoding | (char) | 62 +---------+-------+--------+---------------+-----------------------+ 63 | lpStart | (encoded with lpStartEncoding) | defaults to funcStart | 64 +---------+-----+--------+-----------------+---------------+-------+ 65 | ttypeEncoding | (char) | Encoding of the type_info table | 66 +---------------+-+------+----+----------------------------+----------------+ 67 | classInfoOffset | (ULEB128) | Offset to type_info table, defaults to null | 68 +-----------------++--------+-+----------------------------+----------------+ 69 | callSiteEncoding | (char) | Encoding for Call Site Table | 70 +------------------+--+-----+-----+------------------------+--------------------------+ 71 | callSiteTableLength | (ULEB128) | Call Site Table length, used to find Action table | 72 +---------------------+-----------+---------------------------------------------------+ 73 #ifndef __USING_SJLJ_EXCEPTIONS__ 74 +---------------------+-----------+------------------------------------------------+ 75 | Beginning of Call Site Table The current ip lies within the | 76 | ... (start, length) range of one of these | 77 | call sites. There may be action needed. | 78 | +-------------+---------------------------------+------------------------------+ | 79 | | start | (encoded with callSiteEncoding) | offset relative to funcStart | | 80 | | length | (encoded with callSiteEncoding) | length of code fragment | | 81 | | landingPad | (encoded with callSiteEncoding) | offset relative to lpStart | | 82 | | actionEntry | (ULEB128) | Action Table Index 1-based | | 83 | | | | actionEntry == 0 -> cleanup | | 84 | +-------------+---------------------------------+------------------------------+ | 85 | ... | 86 +----------------------------------------------------------------------------------+ 87 #else // __USING_SJLJ_EXCEPTIONS__ 88 +---------------------+-----------+------------------------------------------------+ 89 | Beginning of Call Site Table The current ip is a 1-based index into | 90 | ... this table. Or it is -1 meaning no | 91 | action is needed. Or it is 0 meaning | 92 | terminate. | 93 | +-------------+---------------------------------+------------------------------+ | 94 | | landingPad | (ULEB128) | offset relative to lpStart | | 95 | | actionEntry | (ULEB128) | Action Table Index 1-based | | 96 | | | | actionEntry == 0 -> cleanup | | 97 | +-------------+---------------------------------+------------------------------+ | 98 | ... | 99 +----------------------------------------------------------------------------------+ 100 #endif // __USING_SJLJ_EXCEPTIONS__ 101 +---------------------------------------------------------------------+ 102 | Beginning of Action Table ttypeIndex == 0 : cleanup | 103 | ... ttypeIndex > 0 : catch | 104 | ttypeIndex < 0 : exception spec | 105 | +--------------+-----------+--------------------------------------+ | 106 | | ttypeIndex | (SLEB128) | Index into type_info Table (1-based) | | 107 | | actionOffset | (SLEB128) | Offset into next Action Table entry | | 108 | +--------------+-----------+--------------------------------------+ | 109 | ... | 110 +---------------------------------------------------------------------+-----------------+ 111 | type_info Table, but classInfoOffset does *not* point here! | 112 | +----------------+------------------------------------------------+-----------------+ | 113 | | Nth type_info* | Encoded with ttypeEncoding, 0 means catch(...) | ttypeIndex == N | | 114 | +----------------+------------------------------------------------+-----------------+ | 115 | ... | 116 | +----------------+------------------------------------------------+-----------------+ | 117 | | 1st type_info* | Encoded with ttypeEncoding, 0 means catch(...) | ttypeIndex == 1 | | 118 | +----------------+------------------------------------------------+-----------------+ | 119 | +---------------------------------------+-----------+------------------------------+ | 120 | | 1st ttypeIndex for 1st exception spec | (ULEB128) | classInfoOffset points here! | | 121 | | ... | (ULEB128) | | | 122 | | Mth ttypeIndex for 1st exception spec | (ULEB128) | | | 123 | | 0 | (ULEB128) | | | 124 | +---------------------------------------+------------------------------------------+ | 125 | ... | 126 | +---------------------------------------+------------------------------------------+ | 127 | | 0 | (ULEB128) | throw() | | 128 | +---------------------------------------+------------------------------------------+ | 129 | ... | 130 | +---------------------------------------+------------------------------------------+ | 131 | | 1st ttypeIndex for Nth exception spec | (ULEB128) | | | 132 | | ... | (ULEB128) | | | 133 | | Mth ttypeIndex for Nth exception spec | (ULEB128) | | | 134 | | 0 | (ULEB128) | | | 135 | +---------------------------------------+------------------------------------------+ | 136 +---------------------------------------------------------------------------------------+ 137 138 Notes: 139 140 * ttypeIndex in the Action Table, and in the exception spec table, is an index, 141 not a byte count, if positive. It is a negative index offset of 142 classInfoOffset and the sizeof entry depends on ttypeEncoding. 143 But if ttypeIndex is negative, it is a positive 1-based byte offset into the 144 type_info Table. 145 And if ttypeIndex is zero, it refers to a catch (...). 146 147 * landingPad can be 0, this implies there is nothing to be done. 148 149 * landingPad != 0 and actionEntry == 0 implies a cleanup needs to be done 150 @landingPad. 151 152 * A cleanup can also be found under landingPad != 0 and actionEntry != 0 in 153 the Action Table with ttypeIndex == 0. 154 */ 155 156 namespace __cxxabiv1 157 { 158 159 namespace 160 { 161 162 template <class AsType> 163 uintptr_t readPointerHelper(const uint8_t*& p) { 164 AsType value; 165 memcpy(&value, p, sizeof(AsType)); 166 p += sizeof(AsType); 167 return static_cast<uintptr_t>(value); 168 } 169 170 } // end namespace 171 172 extern "C" 173 { 174 175 // private API 176 177 // Heavily borrowed from llvm/examples/ExceptionDemo/ExceptionDemo.cpp 178 179 // DWARF Constants 180 enum 181 { 182 DW_EH_PE_absptr = 0x00, 183 DW_EH_PE_uleb128 = 0x01, 184 DW_EH_PE_udata2 = 0x02, 185 DW_EH_PE_udata4 = 0x03, 186 DW_EH_PE_udata8 = 0x04, 187 DW_EH_PE_sleb128 = 0x09, 188 DW_EH_PE_sdata2 = 0x0A, 189 DW_EH_PE_sdata4 = 0x0B, 190 DW_EH_PE_sdata8 = 0x0C, 191 DW_EH_PE_pcrel = 0x10, 192 DW_EH_PE_textrel = 0x20, 193 DW_EH_PE_datarel = 0x30, 194 DW_EH_PE_funcrel = 0x40, 195 DW_EH_PE_aligned = 0x50, 196 DW_EH_PE_indirect = 0x80, 197 DW_EH_PE_omit = 0xFF 198 }; 199 200 /// Read a uleb128 encoded value and advance pointer 201 /// See Variable Length Data Appendix C in: 202 /// @link http://dwarfstd.org/Dwarf4.pdf @unlink 203 /// @param data reference variable holding memory pointer to decode from 204 /// @returns decoded value 205 static 206 uintptr_t 207 readULEB128(const uint8_t** data) 208 { 209 uintptr_t result = 0; 210 uintptr_t shift = 0; 211 unsigned char byte; 212 const uint8_t *p = *data; 213 do 214 { 215 byte = *p++; 216 result |= static_cast<uintptr_t>(byte & 0x7F) << shift; 217 shift += 7; 218 } while (byte & 0x80); 219 *data = p; 220 return result; 221 } 222 223 /// Read a sleb128 encoded value and advance pointer 224 /// See Variable Length Data Appendix C in: 225 /// @link http://dwarfstd.org/Dwarf4.pdf @unlink 226 /// @param data reference variable holding memory pointer to decode from 227 /// @returns decoded value 228 static 229 intptr_t 230 readSLEB128(const uint8_t** data) 231 { 232 uintptr_t result = 0; 233 uintptr_t shift = 0; 234 unsigned char byte; 235 const uint8_t *p = *data; 236 do 237 { 238 byte = *p++; 239 result |= static_cast<uintptr_t>(byte & 0x7F) << shift; 240 shift += 7; 241 } while (byte & 0x80); 242 *data = p; 243 if ((byte & 0x40) && (shift < (sizeof(result) << 3))) 244 result |= static_cast<uintptr_t>(~0) << shift; 245 return static_cast<intptr_t>(result); 246 } 247 248 /// Read a pointer encoded value and advance pointer 249 /// See Variable Length Data in: 250 /// @link http://dwarfstd.org/Dwarf3.pdf @unlink 251 /// @param data reference variable holding memory pointer to decode from 252 /// @param encoding dwarf encoding type 253 /// @param base for adding relative offset, default to 0 254 /// @returns decoded value 255 static 256 uintptr_t 257 readEncodedPointer(const uint8_t** data, uint8_t encoding, uintptr_t base = 0) 258 { 259 uintptr_t result = 0; 260 if (encoding == DW_EH_PE_omit) 261 return result; 262 const uint8_t* p = *data; 263 // first get value 264 switch (encoding & 0x0F) 265 { 266 case DW_EH_PE_absptr: 267 result = readPointerHelper<uintptr_t>(p); 268 break; 269 case DW_EH_PE_uleb128: 270 result = readULEB128(&p); 271 break; 272 case DW_EH_PE_sleb128: 273 result = static_cast<uintptr_t>(readSLEB128(&p)); 274 break; 275 case DW_EH_PE_udata2: 276 result = readPointerHelper<uint16_t>(p); 277 break; 278 case DW_EH_PE_udata4: 279 result = readPointerHelper<uint32_t>(p); 280 break; 281 case DW_EH_PE_udata8: 282 result = readPointerHelper<uint64_t>(p); 283 break; 284 case DW_EH_PE_sdata2: 285 result = readPointerHelper<int16_t>(p); 286 break; 287 case DW_EH_PE_sdata4: 288 result = readPointerHelper<int32_t>(p); 289 break; 290 case DW_EH_PE_sdata8: 291 result = readPointerHelper<int64_t>(p); 292 break; 293 default: 294 // not supported 295 abort(); 296 break; 297 } 298 // then add relative offset 299 switch (encoding & 0x70) 300 { 301 case DW_EH_PE_absptr: 302 // do nothing 303 break; 304 case DW_EH_PE_pcrel: 305 if (result) 306 result += (uintptr_t)(*data); 307 break; 308 case DW_EH_PE_datarel: 309 assert((base != 0) && "DW_EH_PE_datarel is invalid with a base of 0"); 310 if (result) 311 result += base; 312 break; 313 case DW_EH_PE_textrel: 314 case DW_EH_PE_funcrel: 315 case DW_EH_PE_aligned: 316 default: 317 // not supported 318 abort(); 319 break; 320 } 321 // then apply indirection 322 if (result && (encoding & DW_EH_PE_indirect)) 323 result = *((uintptr_t*)result); 324 *data = p; 325 return result; 326 } 327 328 static 329 void 330 call_terminate(bool native_exception, _Unwind_Exception* unwind_exception) 331 { 332 __cxa_begin_catch(unwind_exception); 333 if (native_exception) 334 { 335 // Use the stored terminate_handler if possible 336 __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1; 337 std::__terminate(exception_header->terminateHandler); 338 } 339 std::terminate(); 340 } 341 342 #if defined(_LIBCXXABI_ARM_EHABI) 343 static const void* read_target2_value(const void* ptr) 344 { 345 uintptr_t offset = *reinterpret_cast<const uintptr_t*>(ptr); 346 if (!offset) 347 return 0; 348 // "ARM EABI provides a TARGET2 relocation to describe these typeinfo 349 // pointers. The reason being it allows their precise semantics to be 350 // deferred to the linker. For bare-metal they turn into absolute 351 // relocations. For linux they turn into GOT-REL relocations." 352 // https://gcc.gnu.org/ml/gcc-patches/2009-08/msg00264.html 353 #if defined(LIBCXXABI_BAREMETAL) 354 return reinterpret_cast<const void*>(reinterpret_cast<uintptr_t>(ptr) + 355 offset); 356 #else 357 return *reinterpret_cast<const void **>(reinterpret_cast<uintptr_t>(ptr) + 358 offset); 359 #endif 360 } 361 362 static const __shim_type_info* 363 get_shim_type_info(uint64_t ttypeIndex, const uint8_t* classInfo, 364 uint8_t ttypeEncoding, bool native_exception, 365 _Unwind_Exception* unwind_exception, uintptr_t /*base*/ = 0) 366 { 367 if (classInfo == 0) 368 { 369 // this should not happen. Indicates corrupted eh_table. 370 call_terminate(native_exception, unwind_exception); 371 } 372 373 assert(((ttypeEncoding == DW_EH_PE_absptr) || // LLVM or GCC 4.6 374 (ttypeEncoding == DW_EH_PE_pcrel) || // GCC 4.7 baremetal 375 (ttypeEncoding == (DW_EH_PE_pcrel | DW_EH_PE_indirect))) && // GCC 4.7 linux 376 "Unexpected TTypeEncoding"); 377 (void)ttypeEncoding; 378 379 const uint8_t* ttypePtr = classInfo - ttypeIndex * sizeof(uintptr_t); 380 return reinterpret_cast<const __shim_type_info *>( 381 read_target2_value(ttypePtr)); 382 } 383 #else // !defined(_LIBCXXABI_ARM_EHABI) 384 static 385 const __shim_type_info* 386 get_shim_type_info(uint64_t ttypeIndex, const uint8_t* classInfo, 387 uint8_t ttypeEncoding, bool native_exception, 388 _Unwind_Exception* unwind_exception, uintptr_t base = 0) 389 { 390 if (classInfo == 0) 391 { 392 // this should not happen. Indicates corrupted eh_table. 393 call_terminate(native_exception, unwind_exception); 394 } 395 switch (ttypeEncoding & 0x0F) 396 { 397 case DW_EH_PE_absptr: 398 ttypeIndex *= sizeof(void*); 399 break; 400 case DW_EH_PE_udata2: 401 case DW_EH_PE_sdata2: 402 ttypeIndex *= 2; 403 break; 404 case DW_EH_PE_udata4: 405 case DW_EH_PE_sdata4: 406 ttypeIndex *= 4; 407 break; 408 case DW_EH_PE_udata8: 409 case DW_EH_PE_sdata8: 410 ttypeIndex *= 8; 411 break; 412 default: 413 // this should not happen. Indicates corrupted eh_table. 414 call_terminate(native_exception, unwind_exception); 415 } 416 classInfo -= ttypeIndex; 417 return (const __shim_type_info*)readEncodedPointer(&classInfo, 418 ttypeEncoding, base); 419 } 420 #endif // !defined(_LIBCXXABI_ARM_EHABI) 421 422 /* 423 This is checking a thrown exception type, excpType, against a possibly empty 424 list of catchType's which make up an exception spec. 425 426 An exception spec acts like a catch handler, but in reverse. This "catch 427 handler" will catch an excpType if and only if none of the catchType's in 428 the list will catch a excpType. If any catchType in the list can catch an 429 excpType, then this exception spec does not catch the excpType. 430 */ 431 #if defined(_LIBCXXABI_ARM_EHABI) 432 static 433 bool 434 exception_spec_can_catch(int64_t specIndex, const uint8_t* classInfo, 435 uint8_t ttypeEncoding, const __shim_type_info* excpType, 436 void* adjustedPtr, _Unwind_Exception* unwind_exception, 437 uintptr_t /*base*/ = 0) 438 { 439 if (classInfo == 0) 440 { 441 // this should not happen. Indicates corrupted eh_table. 442 call_terminate(false, unwind_exception); 443 } 444 445 assert(((ttypeEncoding == DW_EH_PE_absptr) || // LLVM or GCC 4.6 446 (ttypeEncoding == DW_EH_PE_pcrel) || // GCC 4.7 baremetal 447 (ttypeEncoding == (DW_EH_PE_pcrel | DW_EH_PE_indirect))) && // GCC 4.7 linux 448 "Unexpected TTypeEncoding"); 449 (void)ttypeEncoding; 450 451 // specIndex is negative of 1-based byte offset into classInfo; 452 specIndex = -specIndex; 453 --specIndex; 454 const void** temp = reinterpret_cast<const void**>( 455 reinterpret_cast<uintptr_t>(classInfo) + 456 static_cast<uintptr_t>(specIndex) * sizeof(uintptr_t)); 457 // If any type in the spec list can catch excpType, return false, else return true 458 // adjustments to adjustedPtr are ignored. 459 while (true) 460 { 461 // ARM EHABI exception specification table (filter table) consists of 462 // several pointers which will directly point to the type info object 463 // (instead of ttypeIndex). The table will be terminated with 0. 464 const void** ttypePtr = temp++; 465 if (*ttypePtr == 0) 466 break; 467 // We can get the __shim_type_info simply by performing a 468 // R_ARM_TARGET2 relocation, and cast the result to __shim_type_info. 469 const __shim_type_info* catchType = 470 static_cast<const __shim_type_info*>(read_target2_value(ttypePtr)); 471 void* tempPtr = adjustedPtr; 472 if (catchType->can_catch(excpType, tempPtr)) 473 return false; 474 } 475 return true; 476 } 477 #else 478 static 479 bool 480 exception_spec_can_catch(int64_t specIndex, const uint8_t* classInfo, 481 uint8_t ttypeEncoding, const __shim_type_info* excpType, 482 void* adjustedPtr, _Unwind_Exception* unwind_exception, 483 uintptr_t base = 0) 484 { 485 if (classInfo == 0) 486 { 487 // this should not happen. Indicates corrupted eh_table. 488 call_terminate(false, unwind_exception); 489 } 490 // specIndex is negative of 1-based byte offset into classInfo; 491 specIndex = -specIndex; 492 --specIndex; 493 const uint8_t* temp = classInfo + specIndex; 494 // If any type in the spec list can catch excpType, return false, else return true 495 // adjustments to adjustedPtr are ignored. 496 while (true) 497 { 498 uint64_t ttypeIndex = readULEB128(&temp); 499 if (ttypeIndex == 0) 500 break; 501 const __shim_type_info* catchType = get_shim_type_info(ttypeIndex, 502 classInfo, 503 ttypeEncoding, 504 true, 505 unwind_exception, 506 base); 507 void* tempPtr = adjustedPtr; 508 if (catchType->can_catch(excpType, tempPtr)) 509 return false; 510 } 511 return true; 512 } 513 #endif 514 515 static 516 void* 517 get_thrown_object_ptr(_Unwind_Exception* unwind_exception) 518 { 519 // Even for foreign exceptions, the exception object is *probably* at unwind_exception + 1 520 // Regardless, this library is prohibited from touching a foreign exception 521 void* adjustedPtr = unwind_exception + 1; 522 if (__getExceptionClass(unwind_exception) == kOurDependentExceptionClass) 523 adjustedPtr = ((__cxa_dependent_exception*)adjustedPtr - 1)->primaryException; 524 return adjustedPtr; 525 } 526 527 namespace 528 { 529 530 struct scan_results 531 { 532 int64_t ttypeIndex; // > 0 catch handler, < 0 exception spec handler, == 0 a cleanup 533 const uint8_t* actionRecord; // Currently unused. Retained to ease future maintenance. 534 const uint8_t* languageSpecificData; // Needed only for __cxa_call_unexpected 535 uintptr_t landingPad; // null -> nothing found, else something found 536 void* adjustedPtr; // Used in cxa_exception.cpp 537 _Unwind_Reason_Code reason; // One of _URC_FATAL_PHASE1_ERROR, 538 // _URC_FATAL_PHASE2_ERROR, 539 // _URC_CONTINUE_UNWIND, 540 // _URC_HANDLER_FOUND 541 }; 542 543 } // unnamed namespace 544 545 static 546 void 547 set_registers(_Unwind_Exception* unwind_exception, _Unwind_Context* context, 548 const scan_results& results) 549 { 550 #if defined(__USING_SJLJ_EXCEPTIONS__) 551 #define __builtin_eh_return_data_regno(regno) regno 552 #elif defined(__ibmxl__) 553 // IBM xlclang++ compiler does not support __builtin_eh_return_data_regno. 554 #define __builtin_eh_return_data_regno(regno) regno + 3 555 #endif 556 _Unwind_SetGR(context, __builtin_eh_return_data_regno(0), 557 reinterpret_cast<uintptr_t>(unwind_exception)); 558 _Unwind_SetGR(context, __builtin_eh_return_data_regno(1), 559 static_cast<uintptr_t>(results.ttypeIndex)); 560 _Unwind_SetIP(context, results.landingPad); 561 } 562 563 /* 564 There are 3 types of scans needed: 565 566 1. Scan for handler with native or foreign exception. If handler found, 567 save state and return _URC_HANDLER_FOUND, else return _URC_CONTINUE_UNWIND. 568 May also report an error on invalid input. 569 May terminate for invalid exception table. 570 _UA_SEARCH_PHASE 571 572 2. Scan for handler with foreign exception. Must return _URC_HANDLER_FOUND, 573 or call terminate. 574 _UA_CLEANUP_PHASE && _UA_HANDLER_FRAME && !native_exception 575 576 3. Scan for cleanups. If a handler is found and this isn't forced unwind, 577 then terminate, otherwise ignore the handler and keep looking for cleanup. 578 If a cleanup is found, return _URC_HANDLER_FOUND, else return _URC_CONTINUE_UNWIND. 579 May also report an error on invalid input. 580 May terminate for invalid exception table. 581 _UA_CLEANUP_PHASE && !_UA_HANDLER_FRAME 582 */ 583 584 static void scan_eh_tab(scan_results &results, _Unwind_Action actions, 585 bool native_exception, 586 _Unwind_Exception *unwind_exception, 587 _Unwind_Context *context) { 588 // Initialize results to found nothing but an error 589 results.ttypeIndex = 0; 590 results.actionRecord = 0; 591 results.languageSpecificData = 0; 592 results.landingPad = 0; 593 results.adjustedPtr = 0; 594 results.reason = _URC_FATAL_PHASE1_ERROR; 595 // Check for consistent actions 596 if (actions & _UA_SEARCH_PHASE) 597 { 598 // Do Phase 1 599 if (actions & (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME | _UA_FORCE_UNWIND)) 600 { 601 // None of these flags should be set during Phase 1 602 // Client error 603 results.reason = _URC_FATAL_PHASE1_ERROR; 604 return; 605 } 606 } 607 else if (actions & _UA_CLEANUP_PHASE) 608 { 609 if ((actions & _UA_HANDLER_FRAME) && (actions & _UA_FORCE_UNWIND)) 610 { 611 // _UA_HANDLER_FRAME should only be set if phase 1 found a handler. 612 // If _UA_FORCE_UNWIND is set, phase 1 shouldn't have happened. 613 // Client error 614 results.reason = _URC_FATAL_PHASE2_ERROR; 615 return; 616 } 617 } 618 else // Neither _UA_SEARCH_PHASE nor _UA_CLEANUP_PHASE is set 619 { 620 // One of these should be set. 621 // Client error 622 results.reason = _URC_FATAL_PHASE1_ERROR; 623 return; 624 } 625 // Start scan by getting exception table address 626 const uint8_t *lsda = (const uint8_t *)_Unwind_GetLanguageSpecificData(context); 627 if (lsda == 0) 628 { 629 // There is no exception table 630 results.reason = _URC_CONTINUE_UNWIND; 631 return; 632 } 633 results.languageSpecificData = lsda; 634 #if defined(_AIX) 635 uintptr_t base = _Unwind_GetDataRelBase(context); 636 #else 637 uintptr_t base = 0; 638 #endif 639 // Get the current instruction pointer and offset it before next 640 // instruction in the current frame which threw the exception. 641 uintptr_t ip = _Unwind_GetIP(context) - 1; 642 // Get beginning current frame's code (as defined by the 643 // emitted dwarf code) 644 uintptr_t funcStart = _Unwind_GetRegionStart(context); 645 #ifdef __USING_SJLJ_EXCEPTIONS__ 646 if (ip == uintptr_t(-1)) 647 { 648 // no action 649 results.reason = _URC_CONTINUE_UNWIND; 650 return; 651 } 652 else if (ip == 0) 653 call_terminate(native_exception, unwind_exception); 654 // ip is 1-based index into call site table 655 #else // !__USING_SJLJ_EXCEPTIONS__ 656 uintptr_t ipOffset = ip - funcStart; 657 #endif // !defined(_USING_SLJL_EXCEPTIONS__) 658 const uint8_t* classInfo = NULL; 659 // Note: See JITDwarfEmitter::EmitExceptionTable(...) for corresponding 660 // dwarf emission 661 // Parse LSDA header. 662 uint8_t lpStartEncoding = *lsda++; 663 const uint8_t* lpStart = 664 (const uint8_t*)readEncodedPointer(&lsda, lpStartEncoding, base); 665 if (lpStart == 0) 666 lpStart = (const uint8_t*)funcStart; 667 uint8_t ttypeEncoding = *lsda++; 668 if (ttypeEncoding != DW_EH_PE_omit) 669 { 670 // Calculate type info locations in emitted dwarf code which 671 // were flagged by type info arguments to llvm.eh.selector 672 // intrinsic 673 uintptr_t classInfoOffset = readULEB128(&lsda); 674 classInfo = lsda + classInfoOffset; 675 } 676 // Walk call-site table looking for range that 677 // includes current PC. 678 uint8_t callSiteEncoding = *lsda++; 679 #ifdef __USING_SJLJ_EXCEPTIONS__ 680 (void)callSiteEncoding; // When using SjLj exceptions, callSiteEncoding is never used 681 #endif 682 uint32_t callSiteTableLength = static_cast<uint32_t>(readULEB128(&lsda)); 683 const uint8_t* callSiteTableStart = lsda; 684 const uint8_t* callSiteTableEnd = callSiteTableStart + callSiteTableLength; 685 const uint8_t* actionTableStart = callSiteTableEnd; 686 const uint8_t* callSitePtr = callSiteTableStart; 687 while (callSitePtr < callSiteTableEnd) 688 { 689 // There is one entry per call site. 690 #ifndef __USING_SJLJ_EXCEPTIONS__ 691 // The call sites are non-overlapping in [start, start+length) 692 // The call sites are ordered in increasing value of start 693 uintptr_t start = readEncodedPointer(&callSitePtr, callSiteEncoding); 694 uintptr_t length = readEncodedPointer(&callSitePtr, callSiteEncoding); 695 uintptr_t landingPad = readEncodedPointer(&callSitePtr, callSiteEncoding); 696 uintptr_t actionEntry = readULEB128(&callSitePtr); 697 if ((start <= ipOffset) && (ipOffset < (start + length))) 698 #else // __USING_SJLJ_EXCEPTIONS__ 699 // ip is 1-based index into this table 700 uintptr_t landingPad = readULEB128(&callSitePtr); 701 uintptr_t actionEntry = readULEB128(&callSitePtr); 702 if (--ip == 0) 703 #endif // __USING_SJLJ_EXCEPTIONS__ 704 { 705 // Found the call site containing ip. 706 #ifndef __USING_SJLJ_EXCEPTIONS__ 707 if (landingPad == 0) 708 { 709 // No handler here 710 results.reason = _URC_CONTINUE_UNWIND; 711 return; 712 } 713 landingPad = (uintptr_t)lpStart + landingPad; 714 #else // __USING_SJLJ_EXCEPTIONS__ 715 ++landingPad; 716 #endif // __USING_SJLJ_EXCEPTIONS__ 717 results.landingPad = landingPad; 718 if (actionEntry == 0) 719 { 720 // Found a cleanup 721 results.reason = actions & _UA_SEARCH_PHASE 722 ? _URC_CONTINUE_UNWIND 723 : _URC_HANDLER_FOUND; 724 return; 725 } 726 // Convert 1-based byte offset into 727 const uint8_t* action = actionTableStart + (actionEntry - 1); 728 bool hasCleanup = false; 729 // Scan action entries until you find a matching handler, cleanup, or the end of action list 730 while (true) 731 { 732 const uint8_t* actionRecord = action; 733 int64_t ttypeIndex = readSLEB128(&action); 734 if (ttypeIndex > 0) 735 { 736 // Found a catch, does it actually catch? 737 // First check for catch (...) 738 const __shim_type_info* catchType = 739 get_shim_type_info(static_cast<uint64_t>(ttypeIndex), 740 classInfo, ttypeEncoding, 741 native_exception, unwind_exception, 742 base); 743 if (catchType == 0) 744 { 745 // Found catch (...) catches everything, including 746 // foreign exceptions. This is search phase, cleanup 747 // phase with foreign exception, or forced unwinding. 748 assert(actions & (_UA_SEARCH_PHASE | _UA_HANDLER_FRAME | 749 _UA_FORCE_UNWIND)); 750 results.ttypeIndex = ttypeIndex; 751 results.actionRecord = actionRecord; 752 results.adjustedPtr = 753 get_thrown_object_ptr(unwind_exception); 754 results.reason = _URC_HANDLER_FOUND; 755 return; 756 } 757 // Else this is a catch (T) clause and will never 758 // catch a foreign exception 759 else if (native_exception) 760 { 761 __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1; 762 void* adjustedPtr = get_thrown_object_ptr(unwind_exception); 763 const __shim_type_info* excpType = 764 static_cast<const __shim_type_info*>(exception_header->exceptionType); 765 if (adjustedPtr == 0 || excpType == 0) 766 { 767 // Something very bad happened 768 call_terminate(native_exception, unwind_exception); 769 } 770 if (catchType->can_catch(excpType, adjustedPtr)) 771 { 772 // Found a matching handler. This is either search 773 // phase or forced unwinding. 774 assert(actions & 775 (_UA_SEARCH_PHASE | _UA_FORCE_UNWIND)); 776 results.ttypeIndex = ttypeIndex; 777 results.actionRecord = actionRecord; 778 results.adjustedPtr = adjustedPtr; 779 results.reason = _URC_HANDLER_FOUND; 780 return; 781 } 782 } 783 // Scan next action ... 784 } 785 else if (ttypeIndex < 0) 786 { 787 // Found an exception specification. 788 if (actions & _UA_FORCE_UNWIND) { 789 // Skip if forced unwinding. 790 } else if (native_exception) { 791 // Does the exception spec catch this native exception? 792 __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1; 793 void* adjustedPtr = get_thrown_object_ptr(unwind_exception); 794 const __shim_type_info* excpType = 795 static_cast<const __shim_type_info*>(exception_header->exceptionType); 796 if (adjustedPtr == 0 || excpType == 0) 797 { 798 // Something very bad happened 799 call_terminate(native_exception, unwind_exception); 800 } 801 if (exception_spec_can_catch(ttypeIndex, classInfo, 802 ttypeEncoding, excpType, 803 adjustedPtr, 804 unwind_exception, base)) 805 { 806 // Native exception caught by exception 807 // specification. 808 assert(actions & _UA_SEARCH_PHASE); 809 results.ttypeIndex = ttypeIndex; 810 results.actionRecord = actionRecord; 811 results.adjustedPtr = adjustedPtr; 812 results.reason = _URC_HANDLER_FOUND; 813 return; 814 } 815 } else { 816 // foreign exception caught by exception spec 817 results.ttypeIndex = ttypeIndex; 818 results.actionRecord = actionRecord; 819 results.adjustedPtr = 820 get_thrown_object_ptr(unwind_exception); 821 results.reason = _URC_HANDLER_FOUND; 822 return; 823 } 824 // Scan next action ... 825 } else { 826 hasCleanup = true; 827 } 828 const uint8_t* temp = action; 829 int64_t actionOffset = readSLEB128(&temp); 830 if (actionOffset == 0) 831 { 832 // End of action list. If this is phase 2 and we have found 833 // a cleanup (ttypeIndex=0), return _URC_HANDLER_FOUND; 834 // otherwise return _URC_CONTINUE_UNWIND. 835 results.reason = hasCleanup && actions & _UA_CLEANUP_PHASE 836 ? _URC_HANDLER_FOUND 837 : _URC_CONTINUE_UNWIND; 838 return; 839 } 840 // Go to next action 841 action += actionOffset; 842 } // there is no break out of this loop, only return 843 } 844 #ifndef __USING_SJLJ_EXCEPTIONS__ 845 else if (ipOffset < start) 846 { 847 // There is no call site for this ip 848 // Something bad has happened. We should never get here. 849 // Possible stack corruption. 850 call_terminate(native_exception, unwind_exception); 851 } 852 #endif // !__USING_SJLJ_EXCEPTIONS__ 853 } // there might be some tricky cases which break out of this loop 854 855 // It is possible that no eh table entry specify how to handle 856 // this exception. By spec, terminate it immediately. 857 call_terminate(native_exception, unwind_exception); 858 } 859 860 // public API 861 862 /* 863 The personality function branches on actions like so: 864 865 _UA_SEARCH_PHASE 866 867 If _UA_CLEANUP_PHASE or _UA_HANDLER_FRAME or _UA_FORCE_UNWIND there's 868 an error from above, return _URC_FATAL_PHASE1_ERROR. 869 870 Scan for anything that could stop unwinding: 871 872 1. A catch clause that will catch this exception 873 (will never catch foreign). 874 2. A catch (...) (will always catch foreign). 875 3. An exception spec that will catch this exception 876 (will always catch foreign). 877 If a handler is found 878 If not foreign 879 Save state in header 880 return _URC_HANDLER_FOUND 881 Else a handler not found 882 return _URC_CONTINUE_UNWIND 883 884 _UA_CLEANUP_PHASE 885 886 If _UA_HANDLER_FRAME 887 If _UA_FORCE_UNWIND 888 How did this happen? return _URC_FATAL_PHASE2_ERROR 889 If foreign 890 Do _UA_SEARCH_PHASE to recover state 891 else 892 Recover state from header 893 Transfer control to landing pad. return _URC_INSTALL_CONTEXT 894 895 Else 896 897 This branch handles both normal C++ non-catching handlers (cleanups) 898 and forced unwinding. 899 Scan for anything that can not stop unwinding: 900 901 1. A cleanup. 902 903 If a cleanup is found 904 transfer control to it. return _URC_INSTALL_CONTEXT 905 Else a cleanup is not found: return _URC_CONTINUE_UNWIND 906 */ 907 908 #if !defined(_LIBCXXABI_ARM_EHABI) 909 #if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__) 910 static _Unwind_Reason_Code __gxx_personality_imp 911 #else 912 _LIBCXXABI_FUNC_VIS _Unwind_Reason_Code 913 #ifdef __USING_SJLJ_EXCEPTIONS__ 914 __gxx_personality_sj0 915 #else 916 __gxx_personality_v0 917 #endif 918 #endif 919 (int version, _Unwind_Action actions, uint64_t exceptionClass, 920 _Unwind_Exception* unwind_exception, _Unwind_Context* context) 921 { 922 if (version != 1 || unwind_exception == 0 || context == 0) 923 return _URC_FATAL_PHASE1_ERROR; 924 925 bool native_exception = (exceptionClass & get_vendor_and_language) == 926 (kOurExceptionClass & get_vendor_and_language); 927 scan_results results; 928 // Process a catch handler for a native exception first. 929 if (actions == (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME) && 930 native_exception) { 931 // Reload the results from the phase 1 cache. 932 __cxa_exception* exception_header = 933 (__cxa_exception*)(unwind_exception + 1) - 1; 934 results.ttypeIndex = exception_header->handlerSwitchValue; 935 results.actionRecord = exception_header->actionRecord; 936 results.languageSpecificData = exception_header->languageSpecificData; 937 results.landingPad = 938 reinterpret_cast<uintptr_t>(exception_header->catchTemp); 939 results.adjustedPtr = exception_header->adjustedPtr; 940 941 // Jump to the handler. 942 set_registers(unwind_exception, context, results); 943 // Cache base for calculating the address of ttype in 944 // __cxa_call_unexpected. 945 if (results.ttypeIndex < 0) { 946 #if defined(_AIX) 947 exception_header->catchTemp = (void *)_Unwind_GetDataRelBase(context); 948 #else 949 exception_header->catchTemp = 0; 950 #endif 951 } 952 return _URC_INSTALL_CONTEXT; 953 } 954 955 // In other cases we need to scan LSDA. 956 scan_eh_tab(results, actions, native_exception, unwind_exception, context); 957 if (results.reason == _URC_CONTINUE_UNWIND || 958 results.reason == _URC_FATAL_PHASE1_ERROR) 959 return results.reason; 960 961 if (actions & _UA_SEARCH_PHASE) 962 { 963 // Phase 1 search: All we're looking for in phase 1 is a handler that 964 // halts unwinding 965 assert(results.reason == _URC_HANDLER_FOUND); 966 if (native_exception) { 967 // For a native exception, cache the LSDA result. 968 __cxa_exception* exc = (__cxa_exception*)(unwind_exception + 1) - 1; 969 exc->handlerSwitchValue = static_cast<int>(results.ttypeIndex); 970 exc->actionRecord = results.actionRecord; 971 exc->languageSpecificData = results.languageSpecificData; 972 exc->catchTemp = reinterpret_cast<void*>(results.landingPad); 973 exc->adjustedPtr = results.adjustedPtr; 974 } 975 return _URC_HANDLER_FOUND; 976 } 977 978 assert(actions & _UA_CLEANUP_PHASE); 979 assert(results.reason == _URC_HANDLER_FOUND); 980 set_registers(unwind_exception, context, results); 981 // Cache base for calculating the address of ttype in __cxa_call_unexpected. 982 if (results.ttypeIndex < 0) { 983 __cxa_exception* exception_header = 984 (__cxa_exception*)(unwind_exception + 1) - 1; 985 #if defined(_AIX) 986 exception_header->catchTemp = (void *)_Unwind_GetDataRelBase(context); 987 #else 988 exception_header->catchTemp = 0; 989 #endif 990 } 991 return _URC_INSTALL_CONTEXT; 992 } 993 994 #if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__) 995 extern "C" _LIBCXXABI_FUNC_VIS EXCEPTION_DISPOSITION 996 __gxx_personality_seh0(PEXCEPTION_RECORD ms_exc, void *this_frame, 997 PCONTEXT ms_orig_context, PDISPATCHER_CONTEXT ms_disp) 998 { 999 return _GCC_specific_handler(ms_exc, this_frame, ms_orig_context, ms_disp, 1000 __gxx_personality_imp); 1001 } 1002 #endif 1003 1004 #else 1005 1006 extern "C" _Unwind_Reason_Code __gnu_unwind_frame(_Unwind_Exception*, 1007 _Unwind_Context*); 1008 1009 // Helper function to unwind one frame. 1010 // ARM EHABI 7.3 and 7.4: If the personality function returns _URC_CONTINUE_UNWIND, the 1011 // personality routine should update the virtual register set (VRS) according to the 1012 // corresponding frame unwinding instructions (ARM EHABI 9.3.) 1013 static _Unwind_Reason_Code continue_unwind(_Unwind_Exception* unwind_exception, 1014 _Unwind_Context* context) 1015 { 1016 switch (__gnu_unwind_frame(unwind_exception, context)) { 1017 case _URC_OK: 1018 return _URC_CONTINUE_UNWIND; 1019 case _URC_END_OF_STACK: 1020 return _URC_END_OF_STACK; 1021 default: 1022 return _URC_FAILURE; 1023 } 1024 } 1025 1026 // ARM register names 1027 #if !defined(_LIBUNWIND_VERSION) 1028 static const uint32_t REG_UCB = 12; // Register to save _Unwind_Control_Block 1029 #endif 1030 static const uint32_t REG_SP = 13; 1031 1032 static void save_results_to_barrier_cache(_Unwind_Exception* unwind_exception, 1033 const scan_results& results) 1034 { 1035 unwind_exception->barrier_cache.bitpattern[0] = (uint32_t)results.adjustedPtr; 1036 unwind_exception->barrier_cache.bitpattern[1] = (uint32_t)results.actionRecord; 1037 unwind_exception->barrier_cache.bitpattern[2] = (uint32_t)results.languageSpecificData; 1038 unwind_exception->barrier_cache.bitpattern[3] = (uint32_t)results.landingPad; 1039 unwind_exception->barrier_cache.bitpattern[4] = (uint32_t)results.ttypeIndex; 1040 } 1041 1042 static void load_results_from_barrier_cache(scan_results& results, 1043 const _Unwind_Exception* unwind_exception) 1044 { 1045 results.adjustedPtr = (void*)unwind_exception->barrier_cache.bitpattern[0]; 1046 results.actionRecord = (const uint8_t*)unwind_exception->barrier_cache.bitpattern[1]; 1047 results.languageSpecificData = (const uint8_t*)unwind_exception->barrier_cache.bitpattern[2]; 1048 results.landingPad = (uintptr_t)unwind_exception->barrier_cache.bitpattern[3]; 1049 results.ttypeIndex = (int64_t)(int32_t)unwind_exception->barrier_cache.bitpattern[4]; 1050 } 1051 1052 extern "C" _LIBCXXABI_FUNC_VIS _Unwind_Reason_Code 1053 __gxx_personality_v0(_Unwind_State state, 1054 _Unwind_Exception* unwind_exception, 1055 _Unwind_Context* context) 1056 { 1057 if (unwind_exception == 0 || context == 0) 1058 return _URC_FATAL_PHASE1_ERROR; 1059 1060 bool native_exception = __isOurExceptionClass(unwind_exception); 1061 1062 #if !defined(_LIBUNWIND_VERSION) 1063 // Copy the address of _Unwind_Control_Block to r12 so that 1064 // _Unwind_GetLanguageSpecificData() and _Unwind_GetRegionStart() can 1065 // return correct address. 1066 _Unwind_SetGR(context, REG_UCB, reinterpret_cast<uint32_t>(unwind_exception)); 1067 #endif 1068 1069 // Check the undocumented force unwinding behavior 1070 bool is_force_unwinding = state & _US_FORCE_UNWIND; 1071 state &= ~_US_FORCE_UNWIND; 1072 1073 scan_results results; 1074 switch (state) { 1075 case _US_VIRTUAL_UNWIND_FRAME: 1076 if (is_force_unwinding) 1077 return continue_unwind(unwind_exception, context); 1078 1079 // Phase 1 search: All we're looking for in phase 1 is a handler that halts unwinding 1080 scan_eh_tab(results, _UA_SEARCH_PHASE, native_exception, unwind_exception, context); 1081 if (results.reason == _URC_HANDLER_FOUND) 1082 { 1083 unwind_exception->barrier_cache.sp = _Unwind_GetGR(context, REG_SP); 1084 if (native_exception) 1085 save_results_to_barrier_cache(unwind_exception, results); 1086 return _URC_HANDLER_FOUND; 1087 } 1088 // Did not find the catch handler 1089 if (results.reason == _URC_CONTINUE_UNWIND) 1090 return continue_unwind(unwind_exception, context); 1091 return results.reason; 1092 1093 case _US_UNWIND_FRAME_STARTING: 1094 // TODO: Support force unwinding in the phase 2 search. 1095 // NOTE: In order to call the cleanup functions, _Unwind_ForcedUnwind() 1096 // will call this personality function with (_US_FORCE_UNWIND | 1097 // _US_UNWIND_FRAME_STARTING). 1098 1099 // Phase 2 search 1100 if (unwind_exception->barrier_cache.sp == _Unwind_GetGR(context, REG_SP)) 1101 { 1102 // Found a catching handler in phase 1 1103 if (native_exception) 1104 { 1105 // Load the result from the native exception barrier cache. 1106 load_results_from_barrier_cache(results, unwind_exception); 1107 results.reason = _URC_HANDLER_FOUND; 1108 } 1109 else 1110 { 1111 // Search for the catching handler again for the foreign exception. 1112 scan_eh_tab(results, static_cast<_Unwind_Action>(_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME), 1113 native_exception, unwind_exception, context); 1114 if (results.reason != _URC_HANDLER_FOUND) // phase1 search should guarantee to find one 1115 call_terminate(native_exception, unwind_exception); 1116 } 1117 1118 // Install the context for the catching handler 1119 set_registers(unwind_exception, context, results); 1120 return _URC_INSTALL_CONTEXT; 1121 } 1122 1123 // Either we didn't do a phase 1 search (due to forced unwinding), or 1124 // phase 1 reported no catching-handlers. 1125 // Search for a (non-catching) cleanup 1126 if (is_force_unwinding) 1127 scan_eh_tab( 1128 results, 1129 static_cast<_Unwind_Action>(_UA_CLEANUP_PHASE | _UA_FORCE_UNWIND), 1130 native_exception, unwind_exception, context); 1131 else 1132 scan_eh_tab(results, _UA_CLEANUP_PHASE, native_exception, 1133 unwind_exception, context); 1134 if (results.reason == _URC_HANDLER_FOUND) 1135 { 1136 // Found a non-catching handler 1137 1138 // ARM EHABI 8.4.2: Before we can jump to the cleanup handler, we have to setup some 1139 // internal data structures, so that __cxa_end_cleanup() can get unwind_exception from 1140 // __cxa_get_globals(). 1141 __cxa_begin_cleanup(unwind_exception); 1142 1143 // Install the context for the cleanup handler 1144 set_registers(unwind_exception, context, results); 1145 return _URC_INSTALL_CONTEXT; 1146 } 1147 1148 // Did not find any handler 1149 if (results.reason == _URC_CONTINUE_UNWIND) 1150 return continue_unwind(unwind_exception, context); 1151 return results.reason; 1152 1153 case _US_UNWIND_FRAME_RESUME: 1154 return continue_unwind(unwind_exception, context); 1155 } 1156 1157 // We were called improperly: neither a phase 1 or phase 2 search 1158 return _URC_FATAL_PHASE1_ERROR; 1159 } 1160 #endif 1161 1162 1163 __attribute__((noreturn)) 1164 _LIBCXXABI_FUNC_VIS void 1165 __cxa_call_unexpected(void* arg) 1166 { 1167 _Unwind_Exception* unwind_exception = static_cast<_Unwind_Exception*>(arg); 1168 if (unwind_exception == 0) 1169 call_terminate(false, unwind_exception); 1170 __cxa_begin_catch(unwind_exception); 1171 bool native_old_exception = __isOurExceptionClass(unwind_exception); 1172 std::unexpected_handler u_handler; 1173 std::terminate_handler t_handler; 1174 __cxa_exception* old_exception_header = 0; 1175 int64_t ttypeIndex; 1176 const uint8_t* lsda; 1177 uintptr_t base = 0; 1178 1179 if (native_old_exception) 1180 { 1181 old_exception_header = (__cxa_exception*)(unwind_exception+1) - 1; 1182 t_handler = old_exception_header->terminateHandler; 1183 u_handler = old_exception_header->unexpectedHandler; 1184 // If std::__unexpected(u_handler) rethrows the same exception, 1185 // these values get overwritten by the rethrow. So save them now: 1186 #if defined(_LIBCXXABI_ARM_EHABI) 1187 ttypeIndex = (int64_t)(int32_t)unwind_exception->barrier_cache.bitpattern[4]; 1188 lsda = (const uint8_t*)unwind_exception->barrier_cache.bitpattern[2]; 1189 #else 1190 ttypeIndex = old_exception_header->handlerSwitchValue; 1191 lsda = old_exception_header->languageSpecificData; 1192 base = (uintptr_t)old_exception_header->catchTemp; 1193 #endif 1194 } 1195 else 1196 { 1197 t_handler = std::get_terminate(); 1198 u_handler = std::get_unexpected(); 1199 } 1200 try 1201 { 1202 std::__unexpected(u_handler); 1203 } 1204 catch (...) 1205 { 1206 // If the old exception is foreign, then all we can do is terminate. 1207 // We have no way to recover the needed old exception spec. There's 1208 // no way to pass that information here. And the personality routine 1209 // can't call us directly and do anything but terminate() if we throw 1210 // from here. 1211 if (native_old_exception) 1212 { 1213 // Have: 1214 // old_exception_header->languageSpecificData 1215 // old_exception_header->actionRecord 1216 // old_exception_header->catchTemp, base for calculating ttype 1217 // Need 1218 // const uint8_t* classInfo 1219 // uint8_t ttypeEncoding 1220 uint8_t lpStartEncoding = *lsda++; 1221 const uint8_t* lpStart = 1222 (const uint8_t*)readEncodedPointer(&lsda, lpStartEncoding, base); 1223 (void)lpStart; // purposefully unused. Just needed to increment lsda. 1224 uint8_t ttypeEncoding = *lsda++; 1225 if (ttypeEncoding == DW_EH_PE_omit) 1226 std::__terminate(t_handler); 1227 uintptr_t classInfoOffset = readULEB128(&lsda); 1228 const uint8_t* classInfo = lsda + classInfoOffset; 1229 // Is this new exception catchable by the exception spec at ttypeIndex? 1230 // The answer is obviously yes if the new and old exceptions are the same exception 1231 // If no 1232 // throw; 1233 __cxa_eh_globals* globals = __cxa_get_globals_fast(); 1234 __cxa_exception* new_exception_header = globals->caughtExceptions; 1235 if (new_exception_header == 0) 1236 // This shouldn't be able to happen! 1237 std::__terminate(t_handler); 1238 bool native_new_exception = __isOurExceptionClass(&new_exception_header->unwindHeader); 1239 void* adjustedPtr; 1240 if (native_new_exception && (new_exception_header != old_exception_header)) 1241 { 1242 const __shim_type_info* excpType = 1243 static_cast<const __shim_type_info*>(new_exception_header->exceptionType); 1244 adjustedPtr = 1245 __getExceptionClass(&new_exception_header->unwindHeader) == kOurDependentExceptionClass ? 1246 ((__cxa_dependent_exception*)new_exception_header)->primaryException : 1247 new_exception_header + 1; 1248 if (!exception_spec_can_catch(ttypeIndex, classInfo, ttypeEncoding, 1249 excpType, adjustedPtr, 1250 unwind_exception, base)) 1251 { 1252 // We need to __cxa_end_catch, but for the old exception, 1253 // not the new one. This is a little tricky ... 1254 // Disguise new_exception_header as a rethrown exception, but 1255 // don't actually rethrow it. This means you can temporarily 1256 // end the catch clause enclosing new_exception_header without 1257 // __cxa_end_catch destroying new_exception_header. 1258 new_exception_header->handlerCount = -new_exception_header->handlerCount; 1259 globals->uncaughtExceptions += 1; 1260 // Call __cxa_end_catch for new_exception_header 1261 __cxa_end_catch(); 1262 // Call __cxa_end_catch for old_exception_header 1263 __cxa_end_catch(); 1264 // Renter this catch clause with new_exception_header 1265 __cxa_begin_catch(&new_exception_header->unwindHeader); 1266 // Rethrow new_exception_header 1267 throw; 1268 } 1269 } 1270 // Will a std::bad_exception be catchable by the exception spec at 1271 // ttypeIndex? 1272 // If no 1273 // throw std::bad_exception(); 1274 const __shim_type_info* excpType = 1275 static_cast<const __shim_type_info*>(&typeid(std::bad_exception)); 1276 std::bad_exception be; 1277 adjustedPtr = &be; 1278 if (!exception_spec_can_catch(ttypeIndex, classInfo, ttypeEncoding, 1279 excpType, adjustedPtr, 1280 unwind_exception, base)) 1281 { 1282 // We need to __cxa_end_catch for both the old exception and the 1283 // new exception. Technically we should do it in that order. 1284 // But it is expedient to do it in the opposite order: 1285 // Call __cxa_end_catch for new_exception_header 1286 __cxa_end_catch(); 1287 // Throw std::bad_exception will __cxa_end_catch for 1288 // old_exception_header 1289 throw be; 1290 } 1291 } 1292 } 1293 std::__terminate(t_handler); 1294 } 1295 1296 #if defined(_AIX) 1297 // Personality routine for EH using the range table. Make it an alias of 1298 // __gxx_personality_v0(). 1299 _LIBCXXABI_FUNC_VIS _Unwind_Reason_Code __xlcxx_personality_v1( 1300 int version, _Unwind_Action actions, uint64_t exceptionClass, 1301 _Unwind_Exception* unwind_exception, _Unwind_Context* context) 1302 __attribute__((__alias__("__gxx_personality_v0"))); 1303 #endif 1304 1305 } // extern "C" 1306 1307 } // __cxxabiv1 1308 1309 #if defined(_AIX) 1310 // Include implementation of the personality and helper functions for the 1311 // state table based EH used by IBM legacy compilers xlC and xlclang++ on AIX. 1312 # include "aix_state_tab_eh.inc" 1313 #endif 1314