aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/libunwind/src/DwarfParser.hpp
blob: b5a53166fc3f690e0d81b326ad625b22883910a0 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//
//  Parses DWARF CFIs (FDEs and CIEs).
//
//===----------------------------------------------------------------------===//

#ifndef __DWARF_PARSER_HPP__
#define __DWARF_PARSER_HPP__

#include <inttypes.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#include "libunwind.h"
#include "dwarf2.h"
#include "Registers.hpp"

#include "config.h"

namespace libunwind {

/// CFI_Parser does basic parsing of a CFI (Call Frame Information) records.
/// See DWARF Spec for details:
///    http://refspecs.linuxbase.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
///
template <typename A>
class CFI_Parser {
public:
  typedef typename A::pint_t pint_t;

  /// Information encoded in a CIE (Common Information Entry)
  struct CIE_Info {
    pint_t    cieStart;
    pint_t    cieLength;
    pint_t    cieInstructions;
    uint8_t   pointerEncoding;
    uint8_t   lsdaEncoding;
    uint8_t   personalityEncoding;
    uint8_t   personalityOffsetInCIE;
    pint_t    personality;
    uint32_t  codeAlignFactor;
    int       dataAlignFactor;
    bool      isSignalFrame;
    bool      fdesHaveAugmentationData;
    uint8_t   returnAddressRegister;
#if defined(_LIBUNWIND_TARGET_AARCH64)
    bool      addressesSignedWithBKey;
#endif
  };

  /// Information about an FDE (Frame Description Entry)
  struct FDE_Info {
    pint_t  fdeStart;
    pint_t  fdeLength;
    pint_t  fdeInstructions;
    pint_t  pcStart;
    pint_t  pcEnd;
    pint_t  lsda;
  };

  enum {
    kMaxRegisterNumber = _LIBUNWIND_HIGHEST_DWARF_REGISTER
  };
  enum RegisterSavedWhere {
    kRegisterUnused,
    kRegisterUndefined,
    kRegisterInCFA,
    kRegisterInCFADecrypt, // sparc64 specific
    kRegisterOffsetFromCFA,
    kRegisterInRegister,
    kRegisterAtExpression,
    kRegisterIsExpression
  };
  struct RegisterLocation {
    RegisterSavedWhere location;
    bool initialStateSaved;
    int64_t value;
  };
  /// Information about a frame layout and registers saved determined
  /// by "running" the DWARF FDE "instructions"
  struct PrologInfo {
    uint32_t          cfaRegister;
    int32_t           cfaRegisterOffset;  // CFA = (cfaRegister)+cfaRegisterOffset
    int64_t           cfaExpression;      // CFA = expression
    uint32_t          spExtraArgSize;
    RegisterLocation  savedRegisters[kMaxRegisterNumber + 1];
    enum class InitializeTime { kLazy, kNormal };

    // When saving registers, this data structure is lazily initialized.
    PrologInfo(InitializeTime IT = InitializeTime::kNormal) {
      if (IT == InitializeTime::kNormal)
        memset(this, 0, sizeof(*this));
    }
    void checkSaveRegister(uint64_t reg, PrologInfo &initialState) {
      if (!savedRegisters[reg].initialStateSaved) {
        initialState.savedRegisters[reg] = savedRegisters[reg];
        savedRegisters[reg].initialStateSaved = true;
      }
    }
    void setRegister(uint64_t reg, RegisterSavedWhere newLocation,
                     int64_t newValue, PrologInfo &initialState) {
      checkSaveRegister(reg, initialState);
      savedRegisters[reg].location = newLocation;
      savedRegisters[reg].value = newValue;
    }
    void setRegisterLocation(uint64_t reg, RegisterSavedWhere newLocation,
                             PrologInfo &initialState) {
      checkSaveRegister(reg, initialState);
      savedRegisters[reg].location = newLocation;
    }
    void setRegisterValue(uint64_t reg, int64_t newValue,
                          PrologInfo &initialState) {
      checkSaveRegister(reg, initialState);
      savedRegisters[reg].value = newValue;
    }
    void restoreRegisterToInitialState(uint64_t reg, PrologInfo &initialState) {
      if (savedRegisters[reg].initialStateSaved)
        savedRegisters[reg] = initialState.savedRegisters[reg];
      // else the register still holds its initial state
    }
  };

  struct PrologInfoStackEntry {
    PrologInfoStackEntry(PrologInfoStackEntry *n, const PrologInfo &i)
        : next(n), info(i) {}
    PrologInfoStackEntry *next;
    PrologInfo info;
  };

  struct RememberStack {
    PrologInfoStackEntry *entry;
    RememberStack() : entry(nullptr) {}
    ~RememberStack() {
#if defined(_LIBUNWIND_REMEMBER_CLEANUP_NEEDED)
      // Clean up rememberStack. Even in the case where every
      // DW_CFA_remember_state is paired with a DW_CFA_restore_state,
      // parseInstructions can skip restore opcodes if it reaches the target PC
      // and stops interpreting, so we have to make sure we don't leak memory.
      while (entry) {
        PrologInfoStackEntry *next = entry->next;
        _LIBUNWIND_REMEMBER_FREE(entry);
        entry = next;
      }
#endif
    }
  };

  static bool findFDE(A &addressSpace, pint_t pc, pint_t ehSectionStart,
                      size_t sectionLength, pint_t fdeHint, FDE_Info *fdeInfo,
                      CIE_Info *cieInfo);
  static const char *decodeFDE(A &addressSpace, pint_t fdeStart,
                               FDE_Info *fdeInfo, CIE_Info *cieInfo,
                               bool useCIEInfo = false);
  static bool parseFDEInstructions(A &addressSpace, const FDE_Info &fdeInfo,
                                   const CIE_Info &cieInfo, pint_t upToPC,
                                   int arch, PrologInfo *results);

  static const char *parseCIE(A &addressSpace, pint_t cie, CIE_Info *cieInfo);
};

/// Parse a FDE into a CIE_Info and an FDE_Info. If useCIEInfo is
/// true, treat cieInfo as already-parsed CIE_Info (whose start offset
/// must match the one specified by the FDE) rather than parsing the
/// one indicated within the FDE.
template <typename A>
const char *CFI_Parser<A>::decodeFDE(A &addressSpace, pint_t fdeStart,
                                     FDE_Info *fdeInfo, CIE_Info *cieInfo,
                                     bool useCIEInfo) {
  pint_t p = fdeStart;
  pint_t cfiLength = (pint_t)addressSpace.get32(p);
  p += 4;
  if (cfiLength == 0xffffffff) {
    // 0xffffffff means length is really next 8 bytes
    cfiLength = (pint_t)addressSpace.get64(p);
    p += 8;
  }
  if (cfiLength == 0)
    return "FDE has zero length"; // zero terminator
  uint32_t ciePointer = addressSpace.get32(p);
  if (ciePointer == 0)
    return "FDE is really a CIE"; // this is a CIE not an FDE
  pint_t nextCFI = p + cfiLength;
  pint_t cieStart = p - ciePointer;
  if (useCIEInfo) {
    if (cieInfo->cieStart != cieStart)
      return "CIE start does not match";
  } else {
    const char *err = parseCIE(addressSpace, cieStart, cieInfo);
    if (err != NULL)
      return err;
  }
  p += 4;
  // Parse pc begin and range.
  pint_t pcStart =
      addressSpace.getEncodedP(p, nextCFI, cieInfo->pointerEncoding);
  pint_t pcRange =
      addressSpace.getEncodedP(p, nextCFI, cieInfo->pointerEncoding & 0x0F);
  // Parse rest of info.
  fdeInfo->lsda = 0;
  // Check for augmentation length.
  if (cieInfo->fdesHaveAugmentationData) {
    pint_t augLen = (pint_t)addressSpace.getULEB128(p, nextCFI);
    pint_t endOfAug = p + augLen;
    if (cieInfo->lsdaEncoding != DW_EH_PE_omit) {
      // Peek at value (without indirection).  Zero means no LSDA.
      pint_t lsdaStart = p;
      if (addressSpace.getEncodedP(p, nextCFI, cieInfo->lsdaEncoding & 0x0F) !=
          0) {
        // Reset pointer and re-parse LSDA address.
        p = lsdaStart;
        fdeInfo->lsda =
            addressSpace.getEncodedP(p, nextCFI, cieInfo->lsdaEncoding);
      }
    }
    p = endOfAug;
  }
  fdeInfo->fdeStart = fdeStart;
  fdeInfo->fdeLength = nextCFI - fdeStart;
  fdeInfo->fdeInstructions = p;
  fdeInfo->pcStart = pcStart;
  fdeInfo->pcEnd = pcStart + pcRange;
  return NULL; // success
}

/// Scan an eh_frame section to find an FDE for a pc
template <typename A>
bool CFI_Parser<A>::findFDE(A &addressSpace, pint_t pc, pint_t ehSectionStart,
                            size_t sectionLength, pint_t fdeHint,
                            FDE_Info *fdeInfo, CIE_Info *cieInfo) {
  //fprintf(stderr, "findFDE(0x%llX)\n", (long long)pc);
  pint_t p = (fdeHint != 0) ? fdeHint : ehSectionStart;
  const pint_t ehSectionEnd = (sectionLength == SIZE_MAX)
                                  ? static_cast<pint_t>(-1)
                                  : (ehSectionStart + sectionLength);
  while (p < ehSectionEnd) {
    pint_t currentCFI = p;
    //fprintf(stderr, "findFDE() CFI at 0x%llX\n", (long long)p);
    pint_t cfiLength = addressSpace.get32(p);
    p += 4;
    if (cfiLength == 0xffffffff) {
      // 0xffffffff means length is really next 8 bytes
      cfiLength = (pint_t)addressSpace.get64(p);
      p += 8;
    }
    if (cfiLength == 0)
      return false; // zero terminator
    uint32_t id = addressSpace.get32(p);
    if (id == 0) {
      // Skip over CIEs.
      p += cfiLength;
    } else {
      // Process FDE to see if it covers pc.
      pint_t nextCFI = p + cfiLength;
      uint32_t ciePointer = addressSpace.get32(p);
      pint_t cieStart = p - ciePointer;
      // Validate pointer to CIE is within section.
      if ((ehSectionStart <= cieStart) && (cieStart < ehSectionEnd)) {
        if (parseCIE(addressSpace, cieStart, cieInfo) == NULL) {
          p += 4;
          // Parse pc begin and range.
          pint_t pcStart =
              addressSpace.getEncodedP(p, nextCFI, cieInfo->pointerEncoding);
          pint_t pcRange = addressSpace.getEncodedP(
              p, nextCFI, cieInfo->pointerEncoding & 0x0F);
          // Test if pc is within the function this FDE covers.
          if ((pcStart < pc) && (pc <= pcStart + pcRange)) {
            // parse rest of info
            fdeInfo->lsda = 0;
            // check for augmentation length
            if (cieInfo->fdesHaveAugmentationData) {
              pint_t augLen = (pint_t)addressSpace.getULEB128(p, nextCFI);
              pint_t endOfAug = p + augLen;
              if (cieInfo->lsdaEncoding != DW_EH_PE_omit) {
                // Peek at value (without indirection).  Zero means no LSDA.
                pint_t lsdaStart = p;
                if (addressSpace.getEncodedP(
                        p, nextCFI, cieInfo->lsdaEncoding & 0x0F) != 0) {
                  // Reset pointer and re-parse LSDA address.
                  p = lsdaStart;
                  fdeInfo->lsda = addressSpace
                      .getEncodedP(p, nextCFI, cieInfo->lsdaEncoding);
                }
              }
              p = endOfAug;
            }
            fdeInfo->fdeStart = currentCFI;
            fdeInfo->fdeLength = nextCFI - currentCFI;
            fdeInfo->fdeInstructions = p;
            fdeInfo->pcStart = pcStart;
            fdeInfo->pcEnd = pcStart + pcRange;
            return true;
          } else {
            // pc is not in begin/range, skip this FDE
          }
        } else {
          // Malformed CIE, now augmentation describing pc range encoding.
        }
      } else {
        // malformed FDE.  CIE is bad
      }
      p = nextCFI;
    }
  }
  return false;
}

/// Extract info from a CIE
template <typename A>
const char *CFI_Parser<A>::parseCIE(A &addressSpace, pint_t cie,
                                    CIE_Info *cieInfo) {
  cieInfo->pointerEncoding = 0;
  cieInfo->lsdaEncoding = DW_EH_PE_omit;
  cieInfo->personalityEncoding = 0;
  cieInfo->personalityOffsetInCIE = 0;
  cieInfo->personality = 0;
  cieInfo->codeAlignFactor = 0;
  cieInfo->dataAlignFactor = 0;
  cieInfo->isSignalFrame = false;
  cieInfo->fdesHaveAugmentationData = false;
#if defined(_LIBUNWIND_TARGET_AARCH64)
  cieInfo->addressesSignedWithBKey = false;
#endif
  cieInfo->cieStart = cie;
  pint_t p = cie;
  pint_t cieLength = (pint_t)addressSpace.get32(p);
  p += 4;
  pint_t cieContentEnd = p + cieLength;
  if (cieLength == 0xffffffff) {
    // 0xffffffff means length is really next 8 bytes
    cieLength = (pint_t)addressSpace.get64(p);
    p += 8;
    cieContentEnd = p + cieLength;
  }
  if (cieLength == 0)
    return NULL;
  // CIE ID is always 0
  if (addressSpace.get32(p) != 0)
    return "CIE ID is not zero";
  p += 4;
  // Version is always 1 or 3
  uint8_t version = addressSpace.get8(p);
  if ((version != 1) && (version != 3))
    return "CIE version is not 1 or 3";
  ++p;
  // save start of augmentation string and find end
  pint_t strStart = p;
  while (addressSpace.get8(p) != 0)
    ++p;
  ++p;
  // parse code aligment factor
  cieInfo->codeAlignFactor = (uint32_t)addressSpace.getULEB128(p, cieContentEnd);
  // parse data alignment factor
  cieInfo->dataAlignFactor = (int)addressSpace.getSLEB128(p, cieContentEnd);
  // parse return address register
  uint64_t raReg = (version == 1) ? addressSpace.get8(p++)
                                  : addressSpace.getULEB128(p, cieContentEnd);
  assert(raReg < 255 && "return address register too large");
  cieInfo->returnAddressRegister = (uint8_t)raReg;
  // parse augmentation data based on augmentation string
  const char *result = NULL;
  if (addressSpace.get8(strStart) == 'z') {
    // parse augmentation data length
    addressSpace.getULEB128(p, cieContentEnd);
    for (pint_t s = strStart; addressSpace.get8(s) != '\0'; ++s) {
      switch (addressSpace.get8(s)) {
      case 'z':
        cieInfo->fdesHaveAugmentationData = true;
        break;
      case 'P':
        cieInfo->personalityEncoding = addressSpace.get8(p);
        ++p;
        cieInfo->personalityOffsetInCIE = (uint8_t)(p - cie);
        cieInfo->personality = addressSpace
            .getEncodedP(p, cieContentEnd, cieInfo->personalityEncoding);
        break;
      case 'L':
        cieInfo->lsdaEncoding = addressSpace.get8(p);
        ++p;
        break;
      case 'R':
        cieInfo->pointerEncoding = addressSpace.get8(p);
        ++p;
        break;
      case 'S':
        cieInfo->isSignalFrame = true;
        break;
#if defined(_LIBUNWIND_TARGET_AARCH64)
      case 'B':
        cieInfo->addressesSignedWithBKey = true;
        break;
#endif
      default:
        // ignore unknown letters
        break;
      }
    }
  }
  cieInfo->cieLength = cieContentEnd - cieInfo->cieStart;
  cieInfo->cieInstructions = p;
  return result;
}


/// "run" the DWARF instructions and create the abstact PrologInfo for an FDE
template <typename A>
bool CFI_Parser<A>::parseFDEInstructions(A &addressSpace,
                                         const FDE_Info &fdeInfo,
                                         const CIE_Info &cieInfo, pint_t upToPC,
                                         int arch, PrologInfo *results) {
  // Alloca is used for the allocation of the rememberStack entries. It removes
  // the dependency on new/malloc but the below for loop can not be refactored
  // into functions. Entry could be saved during the processing of a CIE and
  // restored by an FDE.
  RememberStack rememberStack;

  struct ParseInfo {
    pint_t instructions;
    pint_t instructionsEnd;
    pint_t pcoffset;
  };

  ParseInfo parseInfoArray[] = {
      {cieInfo.cieInstructions, cieInfo.cieStart + cieInfo.cieLength,
       (pint_t)(-1)},
      {fdeInfo.fdeInstructions, fdeInfo.fdeStart + fdeInfo.fdeLength,
       upToPC - fdeInfo.pcStart}};

  for (const auto &info : parseInfoArray) {
    pint_t p = info.instructions;
    pint_t instructionsEnd = info.instructionsEnd;
    pint_t pcoffset = info.pcoffset;
    pint_t codeOffset = 0;

    // initialState initialized as registers in results are modified. Use
    // PrologInfo accessor functions to avoid reading uninitialized data.
    PrologInfo initialState(PrologInfo::InitializeTime::kLazy);

    _LIBUNWIND_TRACE_DWARF("parseFDEInstructions(instructions=0x%0" PRIx64
                           ")\n",
                           static_cast<uint64_t>(instructionsEnd));

    // see DWARF Spec, section 6.4.2 for details on unwind opcodes
    while ((p < instructionsEnd) && (codeOffset < pcoffset)) {
      uint64_t reg;
      uint64_t reg2;
      int64_t offset;
      uint64_t length;
      uint8_t opcode = addressSpace.get8(p);
      uint8_t operand;

      ++p;
      switch (opcode) {
      case DW_CFA_nop:
        _LIBUNWIND_TRACE_DWARF("DW_CFA_nop\n");
        break;
      case DW_CFA_set_loc:
        codeOffset = addressSpace.getEncodedP(p, instructionsEnd,
                                              cieInfo.pointerEncoding);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_set_loc\n");
        break;
      case DW_CFA_advance_loc1:
        codeOffset += (addressSpace.get8(p) * cieInfo.codeAlignFactor);
        p += 1;
        _LIBUNWIND_TRACE_DWARF("DW_CFA_advance_loc1: new offset=%" PRIu64 "\n",
                               static_cast<uint64_t>(codeOffset));
        break;
      case DW_CFA_advance_loc2:
        codeOffset += (addressSpace.get16(p) * cieInfo.codeAlignFactor);
        p += 2;
        _LIBUNWIND_TRACE_DWARF("DW_CFA_advance_loc2: new offset=%" PRIu64 "\n",
                               static_cast<uint64_t>(codeOffset));
        break;
      case DW_CFA_advance_loc4:
        codeOffset += (addressSpace.get32(p) * cieInfo.codeAlignFactor);
        p += 4;
        _LIBUNWIND_TRACE_DWARF("DW_CFA_advance_loc4: new offset=%" PRIu64 "\n",
                               static_cast<uint64_t>(codeOffset));
        break;
      case DW_CFA_offset_extended:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd) *
                 cieInfo.dataAlignFactor;
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_offset_extended DWARF unwind, reg too big");
          return false;
        }
        results->setRegister(reg, kRegisterInCFA, offset, initialState);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_offset_extended(reg=%" PRIu64 ", "
                               "offset=%" PRId64 ")\n",
                               reg, offset);
        break;
      case DW_CFA_restore_extended:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_restore_extended DWARF unwind, reg too big");
          return false;
        }
        results->restoreRegisterToInitialState(reg, initialState);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_restore_extended(reg=%" PRIu64 ")\n",
                               reg);
        break;
      case DW_CFA_undefined:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_undefined DWARF unwind, reg too big");
          return false;
        }
        results->setRegisterLocation(reg, kRegisterUndefined, initialState);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_undefined(reg=%" PRIu64 ")\n", reg);
        break;
      case DW_CFA_same_value:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_same_value DWARF unwind, reg too big");
          return false;
        }
        // <rdar://problem/8456377> DW_CFA_same_value unsupported
        // "same value" means register was stored in frame, but its current
        // value has not changed, so no need to restore from frame.
        // We model this as if the register was never saved.
        results->setRegisterLocation(reg, kRegisterUnused, initialState);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_same_value(reg=%" PRIu64 ")\n", reg);
        break;
      case DW_CFA_register:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        reg2 = addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_register DWARF unwind, reg too big");
          return false;
        }
        if (reg2 > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_register DWARF unwind, reg2 too big");
          return false;
        }
        results->setRegister(reg, kRegisterInRegister, (int64_t)reg2,
                             initialState);
        _LIBUNWIND_TRACE_DWARF(
            "DW_CFA_register(reg=%" PRIu64 ", reg2=%" PRIu64 ")\n", reg, reg2);
        break;
      case DW_CFA_remember_state: {
        // Avoid operator new because that would be an upward dependency.
        // Avoid malloc because it needs heap allocation.
        PrologInfoStackEntry *entry =
            (PrologInfoStackEntry *)_LIBUNWIND_REMEMBER_ALLOC(
                sizeof(PrologInfoStackEntry));
        if (entry != NULL) {
          entry->next = rememberStack.entry;
          entry->info = *results;
          rememberStack.entry = entry;
        } else {
          return false;
        }
        _LIBUNWIND_TRACE_DWARF("DW_CFA_remember_state\n");
        break;
      }
      case DW_CFA_restore_state:
        if (rememberStack.entry != NULL) {
          PrologInfoStackEntry *top = rememberStack.entry;
          *results = top->info;
          rememberStack.entry = top->next;
          _LIBUNWIND_REMEMBER_FREE(top);
        } else {
          return false;
        }
        _LIBUNWIND_TRACE_DWARF("DW_CFA_restore_state\n");
        break;
      case DW_CFA_def_cfa:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0("malformed DW_CFA_def_cfa DWARF unwind, reg too big");
          return false;
        }
        results->cfaRegister = (uint32_t)reg;
        results->cfaRegisterOffset = (int32_t)offset;
        _LIBUNWIND_TRACE_DWARF("DW_CFA_def_cfa(reg=%" PRIu64 ", offset=%" PRIu64
                               ")\n",
                               reg, offset);
        break;
      case DW_CFA_def_cfa_register:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_def_cfa_register DWARF unwind, reg too big");
          return false;
        }
        results->cfaRegister = (uint32_t)reg;
        _LIBUNWIND_TRACE_DWARF("DW_CFA_def_cfa_register(%" PRIu64 ")\n", reg);
        break;
      case DW_CFA_def_cfa_offset:
        results->cfaRegisterOffset =
            (int32_t)addressSpace.getULEB128(p, instructionsEnd);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_def_cfa_offset(%d)\n",
                               results->cfaRegisterOffset);
        break;
      case DW_CFA_def_cfa_expression:
        results->cfaRegister = 0;
        results->cfaExpression = (int64_t)p;
        length = addressSpace.getULEB128(p, instructionsEnd);
        assert(length < static_cast<pint_t>(~0) && "pointer overflow");
        p += static_cast<pint_t>(length);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_def_cfa_expression(expression=0x%" PRIx64
                               ", length=%" PRIu64 ")\n",
                               results->cfaExpression, length);
        break;
      case DW_CFA_expression:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_expression DWARF unwind, reg too big");
          return false;
        }
        results->setRegister(reg, kRegisterAtExpression, (int64_t)p,
                             initialState);
        length = addressSpace.getULEB128(p, instructionsEnd);
        assert(length < static_cast<pint_t>(~0) && "pointer overflow");
        p += static_cast<pint_t>(length);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_expression(reg=%" PRIu64 ", "
                               "expression=0x%" PRIx64 ", "
                               "length=%" PRIu64 ")\n",
                               reg, results->savedRegisters[reg].value, length);
        break;
      case DW_CFA_offset_extended_sf:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_offset_extended_sf DWARF unwind, reg too big");
          return false;
        }
        offset = addressSpace.getSLEB128(p, instructionsEnd) *
                 cieInfo.dataAlignFactor;
        results->setRegister(reg, kRegisterInCFA, offset, initialState);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_offset_extended_sf(reg=%" PRIu64 ", "
                               "offset=%" PRId64 ")\n",
                               reg, offset);
        break;
      case DW_CFA_def_cfa_sf:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        offset = addressSpace.getSLEB128(p, instructionsEnd) *
                 cieInfo.dataAlignFactor;
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_def_cfa_sf DWARF unwind, reg too big");
          return false;
        }
        results->cfaRegister = (uint32_t)reg;
        results->cfaRegisterOffset = (int32_t)offset;
        _LIBUNWIND_TRACE_DWARF("DW_CFA_def_cfa_sf(reg=%" PRIu64 ", "
                               "offset=%" PRId64 ")\n",
                               reg, offset);
        break;
      case DW_CFA_def_cfa_offset_sf:
        results->cfaRegisterOffset =
            (int32_t)(addressSpace.getSLEB128(p, instructionsEnd) *
                      cieInfo.dataAlignFactor);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_def_cfa_offset_sf(%d)\n",
                               results->cfaRegisterOffset);
        break;
      case DW_CFA_val_offset:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG(
              "malformed DW_CFA_val_offset DWARF unwind, reg (%" PRIu64
              ") out of range\n",
              reg);
          return false;
        }
        offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd) *
                 cieInfo.dataAlignFactor;
        results->setRegister(reg, kRegisterOffsetFromCFA, offset, initialState);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_val_offset(reg=%" PRIu64 ", "
                               "offset=%" PRId64 "\n",
                               reg, offset);
        break;
      case DW_CFA_val_offset_sf:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_val_offset_sf DWARF unwind, reg too big");
          return false;
        }
        offset = addressSpace.getSLEB128(p, instructionsEnd) *
                 cieInfo.dataAlignFactor;
        results->setRegister(reg, kRegisterOffsetFromCFA, offset, initialState);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_val_offset_sf(reg=%" PRIu64 ", "
                               "offset=%" PRId64 "\n",
                               reg, offset);
        break;
      case DW_CFA_val_expression:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0(
              "malformed DW_CFA_val_expression DWARF unwind, reg too big");
          return false;
        }
        results->setRegister(reg, kRegisterIsExpression, (int64_t)p,
                             initialState);
        length = addressSpace.getULEB128(p, instructionsEnd);
        assert(length < static_cast<pint_t>(~0) && "pointer overflow");
        p += static_cast<pint_t>(length);
        _LIBUNWIND_TRACE_DWARF("DW_CFA_val_expression(reg=%" PRIu64 ", "
                               "expression=0x%" PRIx64 ", length=%" PRIu64
                               ")\n",
                               reg, results->savedRegisters[reg].value, length);
        break;
      case DW_CFA_GNU_args_size:
        length = addressSpace.getULEB128(p, instructionsEnd);
        results->spExtraArgSize = (uint32_t)length;
        _LIBUNWIND_TRACE_DWARF("DW_CFA_GNU_args_size(%" PRIu64 ")\n", length);
        break;
      case DW_CFA_GNU_negative_offset_extended:
        reg = addressSpace.getULEB128(p, instructionsEnd);
        if (reg > kMaxRegisterNumber) {
          _LIBUNWIND_LOG0("malformed DW_CFA_GNU_negative_offset_extended DWARF "
                          "unwind, reg too big");
          return false;
        }
        offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd) *
                 cieInfo.dataAlignFactor;
        results->setRegister(reg, kRegisterInCFA, -offset, initialState);
        _LIBUNWIND_TRACE_DWARF(
            "DW_CFA_GNU_negative_offset_extended(%" PRId64 ")\n", offset);
        break;

#if defined(_LIBUNWIND_TARGET_AARCH64) || defined(_LIBUNWIND_TARGET_SPARC) || \
    defined(_LIBUNWIND_TARGET_SPARC64)
        // The same constant is used to represent different instructions on
        // AArch64 (negate_ra_state) and SPARC (window_save).
        static_assert(DW_CFA_AARCH64_negate_ra_state == DW_CFA_GNU_window_save,
                      "uses the same constant");
      case DW_CFA_AARCH64_negate_ra_state:
        switch (arch) {
#if defined(_LIBUNWIND_TARGET_AARCH64)
        case REGISTERS_ARM64: {
          int64_t value =
              results->savedRegisters[UNW_AARCH64_RA_SIGN_STATE].value ^ 0x1;
          results->setRegisterValue(UNW_AARCH64_RA_SIGN_STATE, value,
                                    initialState);
          _LIBUNWIND_TRACE_DWARF("DW_CFA_AARCH64_negate_ra_state\n");
        } break;
#endif

#if defined(_LIBUNWIND_TARGET_SPARC)
        // case DW_CFA_GNU_window_save:
        case REGISTERS_SPARC:
          _LIBUNWIND_TRACE_DWARF("DW_CFA_GNU_window_save()\n");
          for (reg = UNW_SPARC_O0; reg <= UNW_SPARC_O7; reg++) {
            results->setRegister(reg, kRegisterInRegister,
                                 ((int64_t)reg - UNW_SPARC_O0) + UNW_SPARC_I0,
                                 initialState);
          }

          for (reg = UNW_SPARC_L0; reg <= UNW_SPARC_I7; reg++) {
            results->setRegister(reg, kRegisterInCFA,
                                 ((int64_t)reg - UNW_SPARC_L0) * 4,
                                 initialState);
          }
          break;
#endif

#if defined(_LIBUNWIND_TARGET_SPARC64)
        // case DW_CFA_GNU_window_save:
        case REGISTERS_SPARC64:
          // Don't save %o0-%o7 on sparc64.
          // https://reviews.llvm.org/D32450#736405

          for (reg = UNW_SPARC_L0; reg <= UNW_SPARC_I7; reg++) {
            if (reg == UNW_SPARC_I7)
              results->setRegister(
                  reg, kRegisterInCFADecrypt,
                  static_cast<int64_t>((reg - UNW_SPARC_L0) * sizeof(pint_t)),
                  initialState);
            else
              results->setRegister(
                  reg, kRegisterInCFA,
                  static_cast<int64_t>((reg - UNW_SPARC_L0) * sizeof(pint_t)),
                  initialState);
          }
          _LIBUNWIND_TRACE_DWARF("DW_CFA_GNU_window_save\n");
          break;
#endif
        }
        break;

#else
        (void)arch;
#endif

      default:
        operand = opcode & 0x3F;
        switch (opcode & 0xC0) {
        case DW_CFA_offset:
          reg = operand;
          if (reg > kMaxRegisterNumber) {
            _LIBUNWIND_LOG("malformed DW_CFA_offset DWARF unwind, reg (%" PRIu64
                           ") out of range",
                           reg);
            return false;
          }
          offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd) *
                   cieInfo.dataAlignFactor;
          results->setRegister(reg, kRegisterInCFA, offset, initialState);
          _LIBUNWIND_TRACE_DWARF("DW_CFA_offset(reg=%d, offset=%" PRId64 ")\n",
                                 operand, offset);
          break;
        case DW_CFA_advance_loc:
          codeOffset += operand * cieInfo.codeAlignFactor;
          _LIBUNWIND_TRACE_DWARF("DW_CFA_advance_loc: new offset=%" PRIu64 "\n",
                                 static_cast<uint64_t>(codeOffset));
          break;
        case DW_CFA_restore:
          reg = operand;
          if (reg > kMaxRegisterNumber) {
            _LIBUNWIND_LOG(
                "malformed DW_CFA_restore DWARF unwind, reg (%" PRIu64
                ") out of range",
                reg);
            return false;
          }
          results->restoreRegisterToInitialState(reg, initialState);
          _LIBUNWIND_TRACE_DWARF("DW_CFA_restore(reg=%" PRIu64 ")\n",
                                 static_cast<uint64_t>(operand));
          break;
        default:
          _LIBUNWIND_TRACE_DWARF("unknown CFA opcode 0x%02X\n", opcode);
          return false;
        }
      }
    }
  }
  return true;
}

} // namespace libunwind

#endif // __DWARF_PARSER_HPP__