1//===--------------------------- Unwind-EHABI.cpp -------------------------===// 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 ARM zero-cost C++ exceptions 9// 10//===----------------------------------------------------------------------===// 11 12#include "Unwind-EHABI.h" 13 14#if defined(_LIBUNWIND_ARM_EHABI) 15 16#include <inttypes.h> 17#include <stdbool.h> 18#include <stdint.h> 19#include <stdio.h> 20#include <stdlib.h> 21#include <string.h> 22 23#include "config.h" 24#include "libunwind.h" 25#include "libunwind_ext.h" 26#include "unwind.h" 27 28namespace { 29 30// Strange order: take words in order, but inside word, take from most to least 31// signinficant byte. 32uint8_t getByte(const uint32_t* data, size_t offset) { 33 const uint8_t* byteData = reinterpret_cast<const uint8_t*>(data); 34#ifdef __LITTLE_ENDIAN__ 35 return byteData[(offset & ~(size_t)0x03) + (3 - (offset & (size_t)0x03))]; 36#else 37 return byteData[offset]; 38#endif 39} 40 41const char* getNextWord(const char* data, uint32_t* out) { 42 *out = *reinterpret_cast<const uint32_t*>(data); 43 return data + 4; 44} 45 46const char* getNextNibble(const char* data, uint32_t* out) { 47 *out = *reinterpret_cast<const uint16_t*>(data); 48 return data + 2; 49} 50 51struct Descriptor { 52 // See # 9.2 53 typedef enum { 54 SU16 = 0, // Short descriptor, 16-bit entries 55 LU16 = 1, // Long descriptor, 16-bit entries 56 LU32 = 3, // Long descriptor, 32-bit entries 57 RESERVED0 = 4, RESERVED1 = 5, RESERVED2 = 6, RESERVED3 = 7, 58 RESERVED4 = 8, RESERVED5 = 9, RESERVED6 = 10, RESERVED7 = 11, 59 RESERVED8 = 12, RESERVED9 = 13, RESERVED10 = 14, RESERVED11 = 15 60 } Format; 61 62 // See # 9.2 63 typedef enum { 64 CLEANUP = 0x0, 65 FUNC = 0x1, 66 CATCH = 0x2, 67 INVALID = 0x4 68 } Kind; 69}; 70 71_Unwind_Reason_Code ProcessDescriptors( 72 _Unwind_State state, 73 _Unwind_Control_Block* ucbp, 74 struct _Unwind_Context* context, 75 Descriptor::Format format, 76 const char* descriptorStart, 77 uint32_t flags) { 78 79 // EHT is inlined in the index using compact form. No descriptors. #5 80 if (flags & 0x1) 81 return _URC_CONTINUE_UNWIND; 82 83 // TODO: We should check the state here, and determine whether we need to 84 // perform phase1 or phase2 unwinding. 85 (void)state; 86 87 const char* descriptor = descriptorStart; 88 uint32_t descriptorWord; 89 getNextWord(descriptor, &descriptorWord); 90 while (descriptorWord) { 91 // Read descriptor based on # 9.2. 92 uint32_t length; 93 uint32_t offset; 94 switch (format) { 95 case Descriptor::LU32: 96 descriptor = getNextWord(descriptor, &length); 97 descriptor = getNextWord(descriptor, &offset); 98 case Descriptor::LU16: 99 descriptor = getNextNibble(descriptor, &length); 100 descriptor = getNextNibble(descriptor, &offset); 101 default: 102 assert(false); 103 return _URC_FAILURE; 104 } 105 106 // See # 9.2 table for decoding the kind of descriptor. It's a 2-bit value. 107 Descriptor::Kind kind = 108 static_cast<Descriptor::Kind>((length & 0x1) | ((offset & 0x1) << 1)); 109 110 // Clear off flag from last bit. 111 length &= ~1u; 112 offset &= ~1u; 113 uintptr_t scopeStart = ucbp->pr_cache.fnstart + offset; 114 uintptr_t scopeEnd = scopeStart + length; 115 uintptr_t pc = _Unwind_GetIP(context); 116 bool isInScope = (scopeStart <= pc) && (pc < scopeEnd); 117 118 switch (kind) { 119 case Descriptor::CLEANUP: { 120 // TODO(ajwong): Handle cleanup descriptors. 121 break; 122 } 123 case Descriptor::FUNC: { 124 // TODO(ajwong): Handle function descriptors. 125 break; 126 } 127 case Descriptor::CATCH: { 128 // Catch descriptors require gobbling one more word. 129 uint32_t landing_pad; 130 descriptor = getNextWord(descriptor, &landing_pad); 131 132 if (isInScope) { 133 // TODO(ajwong): This is only phase1 compatible logic. Implement 134 // phase2. 135 landing_pad = signExtendPrel31(landing_pad & ~0x80000000); 136 if (landing_pad == 0xffffffff) { 137 return _URC_HANDLER_FOUND; 138 } else if (landing_pad == 0xfffffffe) { 139 return _URC_FAILURE; 140 } else { 141 /* 142 bool is_reference_type = landing_pad & 0x80000000; 143 void* matched_object; 144 if (__cxxabiv1::__cxa_type_match( 145 ucbp, reinterpret_cast<const std::type_info *>(landing_pad), 146 is_reference_type, 147 &matched_object) != __cxxabiv1::ctm_failed) 148 return _URC_HANDLER_FOUND; 149 */ 150 _LIBUNWIND_ABORT("Type matching not implemented"); 151 } 152 } 153 break; 154 } 155 default: 156 _LIBUNWIND_ABORT("Invalid descriptor kind found."); 157 } 158 159 getNextWord(descriptor, &descriptorWord); 160 } 161 162 return _URC_CONTINUE_UNWIND; 163} 164 165static _Unwind_Reason_Code unwindOneFrame(_Unwind_State state, 166 _Unwind_Control_Block* ucbp, 167 struct _Unwind_Context* context) { 168 // Read the compact model EHT entry's header # 6.3 169 const uint32_t* unwindingData = ucbp->pr_cache.ehtp; 170 assert((*unwindingData & 0xf0000000) == 0x80000000 && "Must be a compact entry"); 171 Descriptor::Format format = 172 static_cast<Descriptor::Format>((*unwindingData & 0x0f000000) >> 24); 173 174 const char *lsda = 175 reinterpret_cast<const char *>(_Unwind_GetLanguageSpecificData(context)); 176 177 // Handle descriptors before unwinding so they are processed in the context 178 // of the correct stack frame. 179 _Unwind_Reason_Code result = 180 ProcessDescriptors(state, ucbp, context, format, lsda, 181 ucbp->pr_cache.additional); 182 183 if (result != _URC_CONTINUE_UNWIND) 184 return result; 185 186 if (__unw_step(reinterpret_cast<unw_cursor_t *>(context)) != UNW_STEP_SUCCESS) 187 return _URC_FAILURE; 188 return _URC_CONTINUE_UNWIND; 189} 190 191// Generates mask discriminator for _Unwind_VRS_Pop, e.g. for _UVRSC_CORE / 192// _UVRSD_UINT32. 193uint32_t RegisterMask(uint8_t start, uint8_t count_minus_one) { 194 return ((1U << (count_minus_one + 1)) - 1) << start; 195} 196 197// Generates mask discriminator for _Unwind_VRS_Pop, e.g. for _UVRSC_VFP / 198// _UVRSD_DOUBLE. 199uint32_t RegisterRange(uint8_t start, uint8_t count_minus_one) { 200 return ((uint32_t)start << 16) | ((uint32_t)count_minus_one + 1); 201} 202 203} // end anonymous namespace 204 205/** 206 * Decodes an EHT entry. 207 * 208 * @param data Pointer to EHT. 209 * @param[out] off Offset from return value (in bytes) to begin interpretation. 210 * @param[out] len Number of bytes in unwind code. 211 * @return Pointer to beginning of unwind code. 212 */ 213extern "C" const uint32_t* 214decode_eht_entry(const uint32_t* data, size_t* off, size_t* len) { 215 if ((*data & 0x80000000) == 0) { 216 // 6.2: Generic Model 217 // 218 // EHT entry is a prel31 pointing to the PR, followed by data understood 219 // only by the personality routine. Fortunately, all existing assembler 220 // implementations, including GNU assembler, LLVM integrated assembler, 221 // and ARM assembler, assume that the unwind opcodes come after the 222 // personality rountine address. 223 *off = 1; // First byte is size data. 224 *len = (((data[1] >> 24) & 0xff) + 1) * 4; 225 data++; // Skip the first word, which is the prel31 offset. 226 } else { 227 // 6.3: ARM Compact Model 228 // 229 // EHT entries here correspond to the __aeabi_unwind_cpp_pr[012] PRs indeded 230 // by format: 231 Descriptor::Format format = 232 static_cast<Descriptor::Format>((*data & 0x0f000000) >> 24); 233 switch (format) { 234 case Descriptor::SU16: 235 *len = 4; 236 *off = 1; 237 break; 238 case Descriptor::LU16: 239 case Descriptor::LU32: 240 *len = 4 + 4 * ((*data & 0x00ff0000) >> 16); 241 *off = 2; 242 break; 243 default: 244 return nullptr; 245 } 246 } 247 return data; 248} 249 250_LIBUNWIND_EXPORT _Unwind_Reason_Code 251_Unwind_VRS_Interpret(_Unwind_Context *context, const uint32_t *data, 252 size_t offset, size_t len) { 253 bool wrotePC = false; 254 bool finish = false; 255 while (offset < len && !finish) { 256 uint8_t byte = getByte(data, offset++); 257 if ((byte & 0x80) == 0) { 258 uint32_t sp; 259 _Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32, &sp); 260 if (byte & 0x40) 261 sp -= (((uint32_t)byte & 0x3f) << 2) + 4; 262 else 263 sp += ((uint32_t)byte << 2) + 4; 264 _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32, &sp); 265 } else { 266 switch (byte & 0xf0) { 267 case 0x80: { 268 if (offset >= len) 269 return _URC_FAILURE; 270 uint32_t registers = 271 (((uint32_t)byte & 0x0f) << 12) | 272 (((uint32_t)getByte(data, offset++)) << 4); 273 if (!registers) 274 return _URC_FAILURE; 275 if (registers & (1 << 15)) 276 wrotePC = true; 277 _Unwind_VRS_Pop(context, _UVRSC_CORE, registers, _UVRSD_UINT32); 278 break; 279 } 280 case 0x90: { 281 uint8_t reg = byte & 0x0f; 282 if (reg == 13 || reg == 15) 283 return _URC_FAILURE; 284 uint32_t sp; 285 _Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_R0 + reg, 286 _UVRSD_UINT32, &sp); 287 _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32, 288 &sp); 289 break; 290 } 291 case 0xa0: { 292 uint32_t registers = RegisterMask(4, byte & 0x07); 293 if (byte & 0x08) 294 registers |= 1 << 14; 295 _Unwind_VRS_Pop(context, _UVRSC_CORE, registers, _UVRSD_UINT32); 296 break; 297 } 298 case 0xb0: { 299 switch (byte) { 300 case 0xb0: 301 finish = true; 302 break; 303 case 0xb1: { 304 if (offset >= len) 305 return _URC_FAILURE; 306 uint8_t registers = getByte(data, offset++); 307 if (registers & 0xf0 || !registers) 308 return _URC_FAILURE; 309 _Unwind_VRS_Pop(context, _UVRSC_CORE, registers, _UVRSD_UINT32); 310 break; 311 } 312 case 0xb2: { 313 uint32_t addend = 0; 314 uint32_t shift = 0; 315 // This decodes a uleb128 value. 316 while (true) { 317 if (offset >= len) 318 return _URC_FAILURE; 319 uint32_t v = getByte(data, offset++); 320 addend |= (v & 0x7f) << shift; 321 if ((v & 0x80) == 0) 322 break; 323 shift += 7; 324 } 325 uint32_t sp; 326 _Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32, 327 &sp); 328 sp += 0x204 + (addend << 2); 329 _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32, 330 &sp); 331 break; 332 } 333 case 0xb3: { 334 uint8_t v = getByte(data, offset++); 335 _Unwind_VRS_Pop(context, _UVRSC_VFP, 336 RegisterRange(static_cast<uint8_t>(v >> 4), 337 v & 0x0f), _UVRSD_VFPX); 338 break; 339 } 340 case 0xb4: 341 case 0xb5: 342 case 0xb6: 343 case 0xb7: 344 return _URC_FAILURE; 345 default: 346 _Unwind_VRS_Pop(context, _UVRSC_VFP, 347 RegisterRange(8, byte & 0x07), _UVRSD_VFPX); 348 break; 349 } 350 break; 351 } 352 case 0xc0: { 353 switch (byte) { 354#if defined(__ARM_WMMX) 355 case 0xc0: 356 case 0xc1: 357 case 0xc2: 358 case 0xc3: 359 case 0xc4: 360 case 0xc5: 361 _Unwind_VRS_Pop(context, _UVRSC_WMMXD, 362 RegisterRange(10, byte & 0x7), _UVRSD_DOUBLE); 363 break; 364 case 0xc6: { 365 uint8_t v = getByte(data, offset++); 366 uint8_t start = static_cast<uint8_t>(v >> 4); 367 uint8_t count_minus_one = v & 0xf; 368 if (start + count_minus_one >= 16) 369 return _URC_FAILURE; 370 _Unwind_VRS_Pop(context, _UVRSC_WMMXD, 371 RegisterRange(start, count_minus_one), 372 _UVRSD_DOUBLE); 373 break; 374 } 375 case 0xc7: { 376 uint8_t v = getByte(data, offset++); 377 if (!v || v & 0xf0) 378 return _URC_FAILURE; 379 _Unwind_VRS_Pop(context, _UVRSC_WMMXC, v, _UVRSD_DOUBLE); 380 break; 381 } 382#endif 383 case 0xc8: 384 case 0xc9: { 385 uint8_t v = getByte(data, offset++); 386 uint8_t start = 387 static_cast<uint8_t>(((byte == 0xc8) ? 16 : 0) + (v >> 4)); 388 uint8_t count_minus_one = v & 0xf; 389 if (start + count_minus_one >= 32) 390 return _URC_FAILURE; 391 _Unwind_VRS_Pop(context, _UVRSC_VFP, 392 RegisterRange(start, count_minus_one), 393 _UVRSD_DOUBLE); 394 break; 395 } 396 default: 397 return _URC_FAILURE; 398 } 399 break; 400 } 401 case 0xd0: { 402 if (byte & 0x08) 403 return _URC_FAILURE; 404 _Unwind_VRS_Pop(context, _UVRSC_VFP, RegisterRange(8, byte & 0x7), 405 _UVRSD_DOUBLE); 406 break; 407 } 408 default: 409 return _URC_FAILURE; 410 } 411 } 412 } 413 if (!wrotePC) { 414 uint32_t lr; 415 _Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_LR, _UVRSD_UINT32, &lr); 416 _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_IP, _UVRSD_UINT32, &lr); 417 } 418 return _URC_CONTINUE_UNWIND; 419} 420 421extern "C" _LIBUNWIND_EXPORT _Unwind_Reason_Code 422__aeabi_unwind_cpp_pr0(_Unwind_State state, _Unwind_Control_Block *ucbp, 423 _Unwind_Context *context) { 424 return unwindOneFrame(state, ucbp, context); 425} 426 427extern "C" _LIBUNWIND_EXPORT _Unwind_Reason_Code 428__aeabi_unwind_cpp_pr1(_Unwind_State state, _Unwind_Control_Block *ucbp, 429 _Unwind_Context *context) { 430 return unwindOneFrame(state, ucbp, context); 431} 432 433extern "C" _LIBUNWIND_EXPORT _Unwind_Reason_Code 434__aeabi_unwind_cpp_pr2(_Unwind_State state, _Unwind_Control_Block *ucbp, 435 _Unwind_Context *context) { 436 return unwindOneFrame(state, ucbp, context); 437} 438 439static _Unwind_Reason_Code 440unwind_phase1(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *exception_object) { 441 // EHABI #7.3 discusses preserving the VRS in a "temporary VRS" during 442 // phase 1 and then restoring it to the "primary VRS" for phase 2. The 443 // effect is phase 2 doesn't see any of the VRS manipulations from phase 1. 444 // In this implementation, the phases don't share the VRS backing store. 445 // Instead, they are passed the original |uc| and they create a new VRS 446 // from scratch thus achieving the same effect. 447 __unw_init_local(cursor, uc); 448 449 // Walk each frame looking for a place to stop. 450 for (bool handlerNotFound = true; handlerNotFound;) { 451 452 // See if frame has code to run (has personality routine). 453 unw_proc_info_t frameInfo; 454 if (__unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) { 455 _LIBUNWIND_TRACE_UNWINDING( 456 "unwind_phase1(ex_ojb=%p): __unw_get_proc_info " 457 "failed => _URC_FATAL_PHASE1_ERROR", 458 static_cast<void *>(exception_object)); 459 return _URC_FATAL_PHASE1_ERROR; 460 } 461 462 // When tracing, print state information. 463 if (_LIBUNWIND_TRACING_UNWINDING) { 464 char functionBuf[512]; 465 const char *functionName = functionBuf; 466 unw_word_t offset; 467 if ((__unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf), 468 &offset) != UNW_ESUCCESS) || 469 (frameInfo.start_ip + offset > frameInfo.end_ip)) 470 functionName = ".anonymous."; 471 unw_word_t pc; 472 __unw_get_reg(cursor, UNW_REG_IP, &pc); 473 _LIBUNWIND_TRACE_UNWINDING( 474 "unwind_phase1(ex_ojb=%p): pc=0x%" PRIxPTR ", start_ip=0x%" PRIxPTR ", func=%s, " 475 "lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR, 476 static_cast<void *>(exception_object), pc, 477 frameInfo.start_ip, functionName, 478 frameInfo.lsda, frameInfo.handler); 479 } 480 481 // If there is a personality routine, ask it if it will want to stop at 482 // this frame. 483 if (frameInfo.handler != 0) { 484 __personality_routine p = 485 (__personality_routine)(long)(frameInfo.handler); 486 _LIBUNWIND_TRACE_UNWINDING( 487 "unwind_phase1(ex_ojb=%p): calling personality function %p", 488 static_cast<void *>(exception_object), 489 reinterpret_cast<void *>(reinterpret_cast<uintptr_t>(p))); 490 struct _Unwind_Context *context = (struct _Unwind_Context *)(cursor); 491 exception_object->pr_cache.fnstart = frameInfo.start_ip; 492 exception_object->pr_cache.ehtp = 493 (_Unwind_EHT_Header *)frameInfo.unwind_info; 494 exception_object->pr_cache.additional = frameInfo.flags; 495 _Unwind_Reason_Code personalityResult = 496 (*p)(_US_VIRTUAL_UNWIND_FRAME, exception_object, context); 497 _LIBUNWIND_TRACE_UNWINDING( 498 "unwind_phase1(ex_ojb=%p): personality result %d start_ip %x ehtp %p " 499 "additional %x", 500 static_cast<void *>(exception_object), personalityResult, 501 exception_object->pr_cache.fnstart, 502 static_cast<void *>(exception_object->pr_cache.ehtp), 503 exception_object->pr_cache.additional); 504 switch (personalityResult) { 505 case _URC_HANDLER_FOUND: 506 // found a catch clause or locals that need destructing in this frame 507 // stop search and remember stack pointer at the frame 508 handlerNotFound = false; 509 // p should have initialized barrier_cache. EHABI #7.3.5 510 _LIBUNWIND_TRACE_UNWINDING( 511 "unwind_phase1(ex_ojb=%p): _URC_HANDLER_FOUND", 512 static_cast<void *>(exception_object)); 513 return _URC_NO_REASON; 514 515 case _URC_CONTINUE_UNWIND: 516 _LIBUNWIND_TRACE_UNWINDING( 517 "unwind_phase1(ex_ojb=%p): _URC_CONTINUE_UNWIND", 518 static_cast<void *>(exception_object)); 519 // continue unwinding 520 break; 521 522 // EHABI #7.3.3 523 case _URC_FAILURE: 524 return _URC_FAILURE; 525 526 default: 527 // something went wrong 528 _LIBUNWIND_TRACE_UNWINDING( 529 "unwind_phase1(ex_ojb=%p): _URC_FATAL_PHASE1_ERROR", 530 static_cast<void *>(exception_object)); 531 return _URC_FATAL_PHASE1_ERROR; 532 } 533 } 534 } 535 return _URC_NO_REASON; 536} 537 538static _Unwind_Reason_Code unwind_phase2(unw_context_t *uc, unw_cursor_t *cursor, 539 _Unwind_Exception *exception_object, 540 bool resume) { 541 // See comment at the start of unwind_phase1 regarding VRS integrity. 542 __unw_init_local(cursor, uc); 543 544 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p)", 545 static_cast<void *>(exception_object)); 546 int frame_count = 0; 547 548 // Walk each frame until we reach where search phase said to stop. 549 while (true) { 550 // Ask libunwind to get next frame (skip over first which is 551 // _Unwind_RaiseException or _Unwind_Resume). 552 // 553 // Resume only ever makes sense for 1 frame. 554 _Unwind_State state = 555 resume ? _US_UNWIND_FRAME_RESUME : _US_UNWIND_FRAME_STARTING; 556 if (resume && frame_count == 1) { 557 // On a resume, first unwind the _Unwind_Resume() frame. The next frame 558 // is now the landing pad for the cleanup from a previous execution of 559 // phase2. To continue unwindingly correctly, replace VRS[15] with the 560 // IP of the frame that the previous run of phase2 installed the context 561 // for. After this, continue unwinding as if normal. 562 // 563 // See #7.4.6 for details. 564 __unw_set_reg(cursor, UNW_REG_IP, 565 exception_object->unwinder_cache.reserved2); 566 resume = false; 567 } 568 569 // Get info about this frame. 570 unw_word_t sp; 571 unw_proc_info_t frameInfo; 572 __unw_get_reg(cursor, UNW_REG_SP, &sp); 573 if (__unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) { 574 _LIBUNWIND_TRACE_UNWINDING( 575 "unwind_phase2(ex_ojb=%p): __unw_get_proc_info " 576 "failed => _URC_FATAL_PHASE2_ERROR", 577 static_cast<void *>(exception_object)); 578 return _URC_FATAL_PHASE2_ERROR; 579 } 580 581 // When tracing, print state information. 582 if (_LIBUNWIND_TRACING_UNWINDING) { 583 char functionBuf[512]; 584 const char *functionName = functionBuf; 585 unw_word_t offset; 586 if ((__unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf), 587 &offset) != UNW_ESUCCESS) || 588 (frameInfo.start_ip + offset > frameInfo.end_ip)) 589 functionName = ".anonymous."; 590 _LIBUNWIND_TRACE_UNWINDING( 591 "unwind_phase2(ex_ojb=%p): start_ip=0x%" PRIxPTR ", func=%s, sp=0x%" PRIxPTR ", " 592 "lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR "", 593 static_cast<void *>(exception_object), frameInfo.start_ip, 594 functionName, sp, frameInfo.lsda, 595 frameInfo.handler); 596 } 597 598 // If there is a personality routine, tell it we are unwinding. 599 if (frameInfo.handler != 0) { 600 __personality_routine p = 601 (__personality_routine)(long)(frameInfo.handler); 602 struct _Unwind_Context *context = (struct _Unwind_Context *)(cursor); 603 // EHABI #7.2 604 exception_object->pr_cache.fnstart = frameInfo.start_ip; 605 exception_object->pr_cache.ehtp = 606 (_Unwind_EHT_Header *)frameInfo.unwind_info; 607 exception_object->pr_cache.additional = frameInfo.flags; 608 _Unwind_Reason_Code personalityResult = 609 (*p)(state, exception_object, context); 610 switch (personalityResult) { 611 case _URC_CONTINUE_UNWIND: 612 // Continue unwinding 613 _LIBUNWIND_TRACE_UNWINDING( 614 "unwind_phase2(ex_ojb=%p): _URC_CONTINUE_UNWIND", 615 static_cast<void *>(exception_object)); 616 // EHABI #7.2 617 if (sp == exception_object->barrier_cache.sp) { 618 // Phase 1 said we would stop at this frame, but we did not... 619 _LIBUNWIND_ABORT("during phase1 personality function said it would " 620 "stop here, but now in phase2 it did not stop here"); 621 } 622 break; 623 case _URC_INSTALL_CONTEXT: 624 _LIBUNWIND_TRACE_UNWINDING( 625 "unwind_phase2(ex_ojb=%p): _URC_INSTALL_CONTEXT", 626 static_cast<void *>(exception_object)); 627 // Personality routine says to transfer control to landing pad. 628 // We may get control back if landing pad calls _Unwind_Resume(). 629 if (_LIBUNWIND_TRACING_UNWINDING) { 630 unw_word_t pc; 631 __unw_get_reg(cursor, UNW_REG_IP, &pc); 632 __unw_get_reg(cursor, UNW_REG_SP, &sp); 633 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): re-entering " 634 "user code with ip=0x%" PRIxPTR ", sp=0x%" PRIxPTR, 635 static_cast<void *>(exception_object), 636 pc, sp); 637 } 638 639 { 640 // EHABI #7.4.1 says we need to preserve pc for when _Unwind_Resume 641 // is called back, to find this same frame. 642 unw_word_t pc; 643 __unw_get_reg(cursor, UNW_REG_IP, &pc); 644 exception_object->unwinder_cache.reserved2 = (uint32_t)pc; 645 } 646 __unw_resume(cursor); 647 // __unw_resume() only returns if there was an error. 648 return _URC_FATAL_PHASE2_ERROR; 649 650 // # EHABI #7.4.3 651 case _URC_FAILURE: 652 abort(); 653 654 default: 655 // Personality routine returned an unknown result code. 656 _LIBUNWIND_DEBUG_LOG("personality function returned unknown result %d", 657 personalityResult); 658 return _URC_FATAL_PHASE2_ERROR; 659 } 660 } 661 frame_count++; 662 } 663 664 // Clean up phase did not resume at the frame that the search phase 665 // said it would... 666 return _URC_FATAL_PHASE2_ERROR; 667} 668 669/// Called by __cxa_throw. Only returns if there is a fatal error. 670_LIBUNWIND_EXPORT _Unwind_Reason_Code 671_Unwind_RaiseException(_Unwind_Exception *exception_object) { 672 _LIBUNWIND_TRACE_API("_Unwind_RaiseException(ex_obj=%p)", 673 static_cast<void *>(exception_object)); 674 unw_context_t uc; 675 unw_cursor_t cursor; 676 __unw_getcontext(&uc); 677 678 // This field for is for compatibility with GCC to say this isn't a forced 679 // unwind. EHABI #7.2 680 exception_object->unwinder_cache.reserved1 = 0; 681 682 // phase 1: the search phase 683 _Unwind_Reason_Code phase1 = unwind_phase1(&uc, &cursor, exception_object); 684 if (phase1 != _URC_NO_REASON) 685 return phase1; 686 687 // phase 2: the clean up phase 688 return unwind_phase2(&uc, &cursor, exception_object, false); 689} 690 691_LIBUNWIND_EXPORT void _Unwind_Complete(_Unwind_Exception* exception_object) { 692 // This is to be called when exception handling completes to give us a chance 693 // to perform any housekeeping. EHABI #7.2. But we have nothing to do here. 694 (void)exception_object; 695} 696 697/// When _Unwind_RaiseException() is in phase2, it hands control 698/// to the personality function at each frame. The personality 699/// may force a jump to a landing pad in that function, the landing 700/// pad code may then call _Unwind_Resume() to continue with the 701/// unwinding. Note: the call to _Unwind_Resume() is from compiler 702/// geneated user code. All other _Unwind_* routines are called 703/// by the C++ runtime __cxa_* routines. 704/// 705/// Note: re-throwing an exception (as opposed to continuing the unwind) 706/// is implemented by having the code call __cxa_rethrow() which 707/// in turn calls _Unwind_Resume_or_Rethrow(). 708_LIBUNWIND_EXPORT void 709_Unwind_Resume(_Unwind_Exception *exception_object) { 710 _LIBUNWIND_TRACE_API("_Unwind_Resume(ex_obj=%p)", 711 static_cast<void *>(exception_object)); 712 unw_context_t uc; 713 unw_cursor_t cursor; 714 __unw_getcontext(&uc); 715 716 // _Unwind_RaiseException on EHABI will always set the reserved1 field to 0, 717 // which is in the same position as private_1 below. 718 // TODO(ajwong): Who wronte the above? Why is it true? 719 unwind_phase2(&uc, &cursor, exception_object, true); 720 721 // Clients assume _Unwind_Resume() does not return, so all we can do is abort. 722 _LIBUNWIND_ABORT("_Unwind_Resume() can't return"); 723} 724 725/// Called by personality handler during phase 2 to get LSDA for current frame. 726_LIBUNWIND_EXPORT uintptr_t 727_Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) { 728 unw_cursor_t *cursor = (unw_cursor_t *)context; 729 unw_proc_info_t frameInfo; 730 uintptr_t result = 0; 731 if (__unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS) 732 result = (uintptr_t)frameInfo.lsda; 733 _LIBUNWIND_TRACE_API( 734 "_Unwind_GetLanguageSpecificData(context=%p) => 0x%llx", 735 static_cast<void *>(context), (long long)result); 736 return result; 737} 738 739static uint64_t ValueAsBitPattern(_Unwind_VRS_DataRepresentation representation, 740 void* valuep) { 741 uint64_t value = 0; 742 switch (representation) { 743 case _UVRSD_UINT32: 744 case _UVRSD_FLOAT: 745 memcpy(&value, valuep, sizeof(uint32_t)); 746 break; 747 748 case _UVRSD_VFPX: 749 case _UVRSD_UINT64: 750 case _UVRSD_DOUBLE: 751 memcpy(&value, valuep, sizeof(uint64_t)); 752 break; 753 } 754 return value; 755} 756 757_LIBUNWIND_EXPORT _Unwind_VRS_Result 758_Unwind_VRS_Set(_Unwind_Context *context, _Unwind_VRS_RegClass regclass, 759 uint32_t regno, _Unwind_VRS_DataRepresentation representation, 760 void *valuep) { 761 _LIBUNWIND_TRACE_API("_Unwind_VRS_Set(context=%p, regclass=%d, reg=%d, " 762 "rep=%d, value=0x%llX)", 763 static_cast<void *>(context), regclass, regno, 764 representation, 765 ValueAsBitPattern(representation, valuep)); 766 unw_cursor_t *cursor = (unw_cursor_t *)context; 767 switch (regclass) { 768 case _UVRSC_CORE: 769 if (representation != _UVRSD_UINT32 || regno > 15) 770 return _UVRSR_FAILED; 771 return __unw_set_reg(cursor, (unw_regnum_t)(UNW_ARM_R0 + regno), 772 *(unw_word_t *)valuep) == UNW_ESUCCESS 773 ? _UVRSR_OK 774 : _UVRSR_FAILED; 775 case _UVRSC_VFP: 776 if (representation != _UVRSD_VFPX && representation != _UVRSD_DOUBLE) 777 return _UVRSR_FAILED; 778 if (representation == _UVRSD_VFPX) { 779 // Can only touch d0-15 with FSTMFDX. 780 if (regno > 15) 781 return _UVRSR_FAILED; 782 __unw_save_vfp_as_X(cursor); 783 } else { 784 if (regno > 31) 785 return _UVRSR_FAILED; 786 } 787 return __unw_set_fpreg(cursor, (unw_regnum_t)(UNW_ARM_D0 + regno), 788 *(unw_fpreg_t *)valuep) == UNW_ESUCCESS 789 ? _UVRSR_OK 790 : _UVRSR_FAILED; 791#if defined(__ARM_WMMX) 792 case _UVRSC_WMMXC: 793 if (representation != _UVRSD_UINT32 || regno > 3) 794 return _UVRSR_FAILED; 795 return __unw_set_reg(cursor, (unw_regnum_t)(UNW_ARM_WC0 + regno), 796 *(unw_word_t *)valuep) == UNW_ESUCCESS 797 ? _UVRSR_OK 798 : _UVRSR_FAILED; 799 case _UVRSC_WMMXD: 800 if (representation != _UVRSD_DOUBLE || regno > 31) 801 return _UVRSR_FAILED; 802 return __unw_set_fpreg(cursor, (unw_regnum_t)(UNW_ARM_WR0 + regno), 803 *(unw_fpreg_t *)valuep) == UNW_ESUCCESS 804 ? _UVRSR_OK 805 : _UVRSR_FAILED; 806#else 807 case _UVRSC_WMMXC: 808 case _UVRSC_WMMXD: 809 break; 810#endif 811 } 812 _LIBUNWIND_ABORT("unsupported register class"); 813} 814 815static _Unwind_VRS_Result 816_Unwind_VRS_Get_Internal(_Unwind_Context *context, 817 _Unwind_VRS_RegClass regclass, uint32_t regno, 818 _Unwind_VRS_DataRepresentation representation, 819 void *valuep) { 820 unw_cursor_t *cursor = (unw_cursor_t *)context; 821 switch (regclass) { 822 case _UVRSC_CORE: 823 if (representation != _UVRSD_UINT32 || regno > 15) 824 return _UVRSR_FAILED; 825 return __unw_get_reg(cursor, (unw_regnum_t)(UNW_ARM_R0 + regno), 826 (unw_word_t *)valuep) == UNW_ESUCCESS 827 ? _UVRSR_OK 828 : _UVRSR_FAILED; 829 case _UVRSC_VFP: 830 if (representation != _UVRSD_VFPX && representation != _UVRSD_DOUBLE) 831 return _UVRSR_FAILED; 832 if (representation == _UVRSD_VFPX) { 833 // Can only touch d0-15 with FSTMFDX. 834 if (regno > 15) 835 return _UVRSR_FAILED; 836 __unw_save_vfp_as_X(cursor); 837 } else { 838 if (regno > 31) 839 return _UVRSR_FAILED; 840 } 841 return __unw_get_fpreg(cursor, (unw_regnum_t)(UNW_ARM_D0 + regno), 842 (unw_fpreg_t *)valuep) == UNW_ESUCCESS 843 ? _UVRSR_OK 844 : _UVRSR_FAILED; 845#if defined(__ARM_WMMX) 846 case _UVRSC_WMMXC: 847 if (representation != _UVRSD_UINT32 || regno > 3) 848 return _UVRSR_FAILED; 849 return __unw_get_reg(cursor, (unw_regnum_t)(UNW_ARM_WC0 + regno), 850 (unw_word_t *)valuep) == UNW_ESUCCESS 851 ? _UVRSR_OK 852 : _UVRSR_FAILED; 853 case _UVRSC_WMMXD: 854 if (representation != _UVRSD_DOUBLE || regno > 31) 855 return _UVRSR_FAILED; 856 return __unw_get_fpreg(cursor, (unw_regnum_t)(UNW_ARM_WR0 + regno), 857 (unw_fpreg_t *)valuep) == UNW_ESUCCESS 858 ? _UVRSR_OK 859 : _UVRSR_FAILED; 860#else 861 case _UVRSC_WMMXC: 862 case _UVRSC_WMMXD: 863 break; 864#endif 865 } 866 _LIBUNWIND_ABORT("unsupported register class"); 867} 868 869_LIBUNWIND_EXPORT _Unwind_VRS_Result 870_Unwind_VRS_Get(_Unwind_Context *context, _Unwind_VRS_RegClass regclass, 871 uint32_t regno, _Unwind_VRS_DataRepresentation representation, 872 void *valuep) { 873 _Unwind_VRS_Result result = 874 _Unwind_VRS_Get_Internal(context, regclass, regno, representation, 875 valuep); 876 _LIBUNWIND_TRACE_API("_Unwind_VRS_Get(context=%p, regclass=%d, reg=%d, " 877 "rep=%d, value=0x%llX, result = %d)", 878 static_cast<void *>(context), regclass, regno, 879 representation, 880 ValueAsBitPattern(representation, valuep), result); 881 return result; 882} 883 884_Unwind_VRS_Result 885_Unwind_VRS_Pop(_Unwind_Context *context, _Unwind_VRS_RegClass regclass, 886 uint32_t discriminator, 887 _Unwind_VRS_DataRepresentation representation) { 888 _LIBUNWIND_TRACE_API("_Unwind_VRS_Pop(context=%p, regclass=%d, " 889 "discriminator=%d, representation=%d)", 890 static_cast<void *>(context), regclass, discriminator, 891 representation); 892 switch (regclass) { 893 case _UVRSC_WMMXC: 894#if !defined(__ARM_WMMX) 895 break; 896#endif 897 case _UVRSC_CORE: { 898 if (representation != _UVRSD_UINT32) 899 return _UVRSR_FAILED; 900 // When popping SP from the stack, we don't want to override it from the 901 // computed new stack location. See EHABI #7.5.4 table 3. 902 bool poppedSP = false; 903 uint32_t* sp; 904 if (_Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_SP, 905 _UVRSD_UINT32, &sp) != _UVRSR_OK) { 906 return _UVRSR_FAILED; 907 } 908 for (uint32_t i = 0; i < 16; ++i) { 909 if (!(discriminator & static_cast<uint32_t>(1 << i))) 910 continue; 911 uint32_t value = *sp++; 912 if (regclass == _UVRSC_CORE && i == 13) 913 poppedSP = true; 914 if (_Unwind_VRS_Set(context, regclass, i, 915 _UVRSD_UINT32, &value) != _UVRSR_OK) { 916 return _UVRSR_FAILED; 917 } 918 } 919 if (!poppedSP) { 920 return _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_SP, 921 _UVRSD_UINT32, &sp); 922 } 923 return _UVRSR_OK; 924 } 925 case _UVRSC_WMMXD: 926#if !defined(__ARM_WMMX) 927 break; 928#endif 929 case _UVRSC_VFP: { 930 if (representation != _UVRSD_VFPX && representation != _UVRSD_DOUBLE) 931 return _UVRSR_FAILED; 932 uint32_t first = discriminator >> 16; 933 uint32_t count = discriminator & 0xffff; 934 uint32_t end = first+count; 935 uint32_t* sp; 936 if (_Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_SP, 937 _UVRSD_UINT32, &sp) != _UVRSR_OK) { 938 return _UVRSR_FAILED; 939 } 940 // For _UVRSD_VFPX, we're assuming the data is stored in FSTMX "standard 941 // format 1", which is equivalent to FSTMD + a padding word. 942 for (uint32_t i = first; i < end; ++i) { 943 // SP is only 32-bit aligned so don't copy 64-bit at a time. 944 uint64_t w0 = *sp++; 945 uint64_t w1 = *sp++; 946#ifdef __LITTLE_ENDIAN__ 947 uint64_t value = (w1 << 32) | w0; 948#else 949 uint64_t value = (w0 << 32) | w1; 950#endif 951 if (_Unwind_VRS_Set(context, regclass, i, representation, &value) != 952 _UVRSR_OK) 953 return _UVRSR_FAILED; 954 } 955 if (representation == _UVRSD_VFPX) 956 ++sp; 957 return _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32, 958 &sp); 959 } 960 } 961 _LIBUNWIND_ABORT("unsupported register class"); 962} 963 964/// Called by personality handler during phase 2 to find the start of the 965/// function. 966_LIBUNWIND_EXPORT uintptr_t 967_Unwind_GetRegionStart(struct _Unwind_Context *context) { 968 unw_cursor_t *cursor = (unw_cursor_t *)context; 969 unw_proc_info_t frameInfo; 970 uintptr_t result = 0; 971 if (__unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS) 972 result = (uintptr_t)frameInfo.start_ip; 973 _LIBUNWIND_TRACE_API("_Unwind_GetRegionStart(context=%p) => 0x%llX", 974 static_cast<void *>(context), (long long)result); 975 return result; 976} 977 978 979/// Called by personality handler during phase 2 if a foreign exception 980// is caught. 981_LIBUNWIND_EXPORT void 982_Unwind_DeleteException(_Unwind_Exception *exception_object) { 983 _LIBUNWIND_TRACE_API("_Unwind_DeleteException(ex_obj=%p)", 984 static_cast<void *>(exception_object)); 985 if (exception_object->exception_cleanup != NULL) 986 (*exception_object->exception_cleanup)(_URC_FOREIGN_EXCEPTION_CAUGHT, 987 exception_object); 988} 989 990extern "C" _LIBUNWIND_EXPORT _Unwind_Reason_Code 991__gnu_unwind_frame(_Unwind_Exception *exception_object, 992 struct _Unwind_Context *context) { 993 unw_cursor_t *cursor = (unw_cursor_t *)context; 994 if (__unw_step(cursor) != UNW_STEP_SUCCESS) 995 return _URC_FAILURE; 996 return _URC_OK; 997} 998 999#endif // defined(_LIBUNWIND_ARM_EHABI) 1000