1// Copyright 2016 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "src/eh-frame.h"
6
7#include <iomanip>
8#include <ostream>
9
10#if !defined(V8_TARGET_ARCH_X64) && !defined(V8_TARGET_ARCH_ARM) && \
11    !defined(V8_TARGET_ARCH_ARM64)
12
13// Placeholders for unsupported architectures.
14
15namespace v8 {
16namespace internal {
17
18const int EhFrameConstants::kCodeAlignmentFactor = 1;
19const int EhFrameConstants::kDataAlignmentFactor = 1;
20
21void EhFrameWriter::WriteReturnAddressRegisterCode() { UNIMPLEMENTED(); }
22
23void EhFrameWriter::WriteInitialStateInCie() { UNIMPLEMENTED(); }
24
25int EhFrameWriter::RegisterToDwarfCode(Register) {
26  UNIMPLEMENTED();
27  return -1;
28}
29
30#ifdef ENABLE_DISASSEMBLER
31
32const char* EhFrameDisassembler::DwarfRegisterCodeToString(int) {
33  UNIMPLEMENTED();
34  return nullptr;
35}
36
37#endif
38
39}  // namespace internal
40}  // namespace v8
41
42#endif
43
44namespace v8 {
45namespace internal {
46
47STATIC_CONST_MEMBER_DEFINITION const int
48    EhFrameConstants::kEhFrameTerminatorSize;
49STATIC_CONST_MEMBER_DEFINITION const int EhFrameConstants::kEhFrameHdrVersion;
50STATIC_CONST_MEMBER_DEFINITION const int EhFrameConstants::kEhFrameHdrSize;
51
52STATIC_CONST_MEMBER_DEFINITION const uint32_t EhFrameWriter::kInt32Placeholder;
53
54// static
55void EhFrameWriter::WriteEmptyEhFrame(std::ostream& stream) {  // NOLINT
56  stream.put(EhFrameConstants::kEhFrameHdrVersion);
57
58  // .eh_frame pointer encoding specifier.
59  stream.put(EhFrameConstants::kSData4 | EhFrameConstants::kPcRel);
60
61  // Lookup table size encoding.
62  stream.put(EhFrameConstants::kUData4);
63
64  // Lookup table entries encoding.
65  stream.put(EhFrameConstants::kSData4 | EhFrameConstants::kDataRel);
66
67  // Dummy pointers and 0 entries in the lookup table.
68  char dummy_data[EhFrameConstants::kEhFrameHdrSize - 4] = {0};
69  stream.write(&dummy_data[0], sizeof(dummy_data));
70}
71
72EhFrameWriter::EhFrameWriter(Zone* zone)
73    : cie_size_(0),
74      last_pc_offset_(0),
75      writer_state_(InternalState::kUndefined),
76      base_register_(no_reg),
77      base_offset_(0),
78      eh_frame_buffer_(zone) {}
79
80void EhFrameWriter::Initialize() {
81  DCHECK(writer_state_ == InternalState::kUndefined);
82  eh_frame_buffer_.reserve(128);
83  writer_state_ = InternalState::kInitialized;
84  WriteCie();
85  WriteFdeHeader();
86}
87
88void EhFrameWriter::WriteCie() {
89  static const int kCIEIdentifier = 0;
90  static const int kCIEVersion = 3;
91  static const int kAugmentationDataSize = 2;
92  static const byte kAugmentationString[] = {'z', 'L', 'R', 0};
93
94  // Placeholder for the size of the CIE.
95  int size_offset = eh_frame_offset();
96  WriteInt32(kInt32Placeholder);
97
98  // CIE identifier and version.
99  int record_start_offset = eh_frame_offset();
100  WriteInt32(kCIEIdentifier);
101  WriteByte(kCIEVersion);
102
103  // Augmentation data contents descriptor: LSDA and FDE encoding.
104  WriteBytes(&kAugmentationString[0], sizeof(kAugmentationString));
105
106  // Alignment factors.
107  WriteSLeb128(EhFrameConstants::kCodeAlignmentFactor);
108  WriteSLeb128(EhFrameConstants::kDataAlignmentFactor);
109
110  WriteReturnAddressRegisterCode();
111
112  // Augmentation data.
113  WriteULeb128(kAugmentationDataSize);
114  // No language-specific data area (LSDA).
115  WriteByte(EhFrameConstants::kOmit);
116  // FDE pointers encoding.
117  WriteByte(EhFrameConstants::kSData4 | EhFrameConstants::kPcRel);
118
119  // Write directives to build the initial state of the unwinding table.
120  DCHECK_EQ(eh_frame_offset() - size_offset,
121            EhFrameConstants::kInitialStateOffsetInCie);
122  WriteInitialStateInCie();
123
124  WritePaddingToAlignedSize(eh_frame_offset() - record_start_offset);
125
126  int record_end_offset = eh_frame_offset();
127  int encoded_cie_size = record_end_offset - record_start_offset;
128  cie_size_ = record_end_offset - size_offset;
129
130  // Patch the size of the CIE now that we know it.
131  PatchInt32(size_offset, encoded_cie_size);
132}
133
134void EhFrameWriter::WriteFdeHeader() {
135  DCHECK_NE(cie_size_, 0);
136
137  // Placeholder for size of the FDE. Will be filled in Finish().
138  DCHECK_EQ(eh_frame_offset(), fde_offset());
139  WriteInt32(kInt32Placeholder);
140
141  // Backwards offset to the CIE.
142  WriteInt32(cie_size_ + kInt32Size);
143
144  // Placeholder for pointer to procedure. Will be filled in Finish().
145  DCHECK_EQ(eh_frame_offset(), GetProcedureAddressOffset());
146  WriteInt32(kInt32Placeholder);
147
148  // Placeholder for size of the procedure. Will be filled in Finish().
149  DCHECK_EQ(eh_frame_offset(), GetProcedureSizeOffset());
150  WriteInt32(kInt32Placeholder);
151
152  // No augmentation data.
153  WriteByte(0);
154}
155
156void EhFrameWriter::WriteEhFrameHdr(int code_size) {
157  DCHECK(writer_state_ == InternalState::kInitialized);
158
159  //
160  // In order to calculate offsets in the .eh_frame_hdr, we must know the layout
161  // of the DSO generated by perf inject, which is assumed to be the following:
162  //
163  //  |      ...      |                        |
164  //  +---------------+ <-- (F) ---            |  Larger offsets in file
165  //  |               |           ^            |
166  //  |  Instructions |           | .text      v
167  //  |               |           v
168  //  +---------------+ <-- (E) ---
169  //  |///////////////|
170  //  |////Padding////|
171  //  |///////////////|
172  //  +---------------+ <-- (D) ---
173  //  |               |           ^
174  //  |      CIE      |           |
175  //  |               |           |
176  //  +---------------+ <-- (C)   |
177  //  |               |           | .eh_frame
178  //  |      FDE      |           |
179  //  |               |           |
180  //  +---------------+           |
181  //  |   terminator  |           v
182  //  +---------------+ <-- (B) ---
183  //  |    version    |           ^
184  //  +---------------+           |
185  //  |   encoding    |           |
186  //  |  specifiers   |           |
187  //  +---------------+ <---(A)   | .eh_frame_hdr
188  //  |   offset to   |           |
189  //  |   .eh_frame   |           |
190  //  +---------------+           |
191  //  |      ...      |          ...
192  //
193  // (F) is aligned to a 16-byte boundary.
194  // (D) is aligned to a  8-byte boundary.
195  // (B) is aligned to a  4-byte boundary.
196  // (C), (E) and (A) have no alignment requirements.
197  //
198  // The distance between (A) and (B) is 4 bytes.
199  //
200  // The size of the FDE is required to be a multiple of the pointer size, which
201  // means that (B) will be naturally aligned to a 4-byte boundary on all the
202  // architectures we support.
203  //
204  // Because (E) has no alignment requirements, there is padding between (E) and
205  // (D). (F) is aligned at a 16-byte boundary, thus to a 8-byte one as well.
206  //
207
208  int eh_frame_size = eh_frame_offset();
209
210  WriteByte(EhFrameConstants::kEhFrameHdrVersion);
211
212  // .eh_frame pointer encoding specifier.
213  WriteByte(EhFrameConstants::kSData4 | EhFrameConstants::kPcRel);
214  // Lookup table size encoding specifier.
215  WriteByte(EhFrameConstants::kUData4);
216  // Lookup table entries encoding specifier.
217  WriteByte(EhFrameConstants::kSData4 | EhFrameConstants::kDataRel);
218
219  // Pointer to .eh_frame, relative to this offset (A -> D in the diagram).
220  WriteInt32(-(eh_frame_size + EhFrameConstants::kFdeVersionSize +
221               EhFrameConstants::kFdeEncodingSpecifiersSize));
222
223  // Number of entries in the LUT, one for the only routine.
224  WriteInt32(1);
225
226  // Pointer to the start of the routine, relative to the beginning of the
227  // .eh_frame_hdr (B -> F in the diagram).
228  WriteInt32(-(RoundUp(code_size, 8) + eh_frame_size));
229
230  // Pointer to the start of the associated FDE, relative to the start of the
231  // .eh_frame_hdr (B -> C  in the diagram).
232  WriteInt32(-(eh_frame_size - cie_size_));
233
234  DCHECK_EQ(eh_frame_offset() - eh_frame_size,
235            EhFrameConstants::kEhFrameHdrSize);
236}
237
238void EhFrameWriter::WritePaddingToAlignedSize(int unpadded_size) {
239  DCHECK(writer_state_ == InternalState::kInitialized);
240  DCHECK_GE(unpadded_size, 0);
241
242  int padding_size = RoundUp(unpadded_size, kPointerSize) - unpadded_size;
243
244  byte nop = static_cast<byte>(EhFrameConstants::DwarfOpcodes::kNop);
245  static const byte kPadding[] = {nop, nop, nop, nop, nop, nop, nop, nop};
246  DCHECK_LE(padding_size, static_cast<int>(sizeof(kPadding)));
247  WriteBytes(&kPadding[0], padding_size);
248}
249
250void EhFrameWriter::AdvanceLocation(int pc_offset) {
251  DCHECK(writer_state_ == InternalState::kInitialized);
252  DCHECK_GE(pc_offset, last_pc_offset_);
253  uint32_t delta = pc_offset - last_pc_offset_;
254
255  DCHECK_EQ(delta % EhFrameConstants::kCodeAlignmentFactor, 0u);
256  uint32_t factored_delta = delta / EhFrameConstants::kCodeAlignmentFactor;
257
258  if (factored_delta <= EhFrameConstants::kLocationMask) {
259    WriteByte((EhFrameConstants::kLocationTag
260               << EhFrameConstants::kLocationMaskSize) |
261              (factored_delta & EhFrameConstants::kLocationMask));
262  } else if (factored_delta <= kMaxUInt8) {
263    WriteOpcode(EhFrameConstants::DwarfOpcodes::kAdvanceLoc1);
264    WriteByte(factored_delta);
265  } else if (factored_delta <= kMaxUInt16) {
266    WriteOpcode(EhFrameConstants::DwarfOpcodes::kAdvanceLoc2);
267    WriteInt16(factored_delta);
268  } else {
269    WriteOpcode(EhFrameConstants::DwarfOpcodes::kAdvanceLoc4);
270    WriteInt32(factored_delta);
271  }
272
273  last_pc_offset_ = pc_offset;
274}
275
276void EhFrameWriter::SetBaseAddressOffset(int base_offset) {
277  DCHECK(writer_state_ == InternalState::kInitialized);
278  DCHECK_GE(base_offset, 0);
279  WriteOpcode(EhFrameConstants::DwarfOpcodes::kDefCfaOffset);
280  WriteULeb128(base_offset);
281  base_offset_ = base_offset;
282}
283
284void EhFrameWriter::SetBaseAddressRegister(Register base_register) {
285  DCHECK(writer_state_ == InternalState::kInitialized);
286  int code = RegisterToDwarfCode(base_register);
287  WriteOpcode(EhFrameConstants::DwarfOpcodes::kDefCfaRegister);
288  WriteULeb128(code);
289  base_register_ = base_register;
290}
291
292void EhFrameWriter::SetBaseAddressRegisterAndOffset(Register base_register,
293                                                    int base_offset) {
294  DCHECK(writer_state_ == InternalState::kInitialized);
295  DCHECK_GE(base_offset, 0);
296  int code = RegisterToDwarfCode(base_register);
297  WriteOpcode(EhFrameConstants::DwarfOpcodes::kDefCfa);
298  WriteULeb128(code);
299  WriteULeb128(base_offset);
300  base_offset_ = base_offset;
301  base_register_ = base_register;
302}
303
304void EhFrameWriter::RecordRegisterSavedToStack(int register_code, int offset) {
305  DCHECK(writer_state_ == InternalState::kInitialized);
306  DCHECK_EQ(offset % EhFrameConstants::kDataAlignmentFactor, 0);
307  int factored_offset = offset / EhFrameConstants::kDataAlignmentFactor;
308  if (factored_offset >= 0) {
309    DCHECK_LE(register_code, EhFrameConstants::kSavedRegisterMask);
310    WriteByte((EhFrameConstants::kSavedRegisterTag
311               << EhFrameConstants::kSavedRegisterMaskSize) |
312              (register_code & EhFrameConstants::kSavedRegisterMask));
313    WriteULeb128(factored_offset);
314  } else {
315    WriteOpcode(EhFrameConstants::DwarfOpcodes::kOffsetExtendedSf);
316    WriteULeb128(register_code);
317    WriteSLeb128(factored_offset);
318  }
319}
320
321void EhFrameWriter::RecordRegisterNotModified(Register name) {
322  DCHECK(writer_state_ == InternalState::kInitialized);
323  WriteOpcode(EhFrameConstants::DwarfOpcodes::kSameValue);
324  WriteULeb128(RegisterToDwarfCode(name));
325}
326
327void EhFrameWriter::RecordRegisterFollowsInitialRule(Register name) {
328  DCHECK(writer_state_ == InternalState::kInitialized);
329  int code = RegisterToDwarfCode(name);
330  DCHECK_LE(code, EhFrameConstants::kFollowInitialRuleMask);
331  WriteByte((EhFrameConstants::kFollowInitialRuleTag
332             << EhFrameConstants::kFollowInitialRuleMaskSize) |
333            (code & EhFrameConstants::kFollowInitialRuleMask));
334}
335
336void EhFrameWriter::Finish(int code_size) {
337  DCHECK(writer_state_ == InternalState::kInitialized);
338  DCHECK_GE(eh_frame_offset(), cie_size_);
339
340  DCHECK_GE(eh_frame_offset(), fde_offset() + kInt32Size);
341  WritePaddingToAlignedSize(eh_frame_offset() - fde_offset() - kInt32Size);
342
343  // Write the size of the FDE now that we know it.
344  // The encoded size does not include the size field itself.
345  int encoded_fde_size = eh_frame_offset() - fde_offset() - kInt32Size;
346  PatchInt32(fde_offset(), encoded_fde_size);
347
348  // Write size and offset to procedure.
349  PatchInt32(GetProcedureAddressOffset(),
350             -(RoundUp(code_size, 8) + GetProcedureAddressOffset()));
351  PatchInt32(GetProcedureSizeOffset(), code_size);
352
353  // Terminate the .eh_frame.
354  static const byte kTerminator[EhFrameConstants::kEhFrameTerminatorSize] = {0};
355  WriteBytes(&kTerminator[0], EhFrameConstants::kEhFrameTerminatorSize);
356
357  WriteEhFrameHdr(code_size);
358
359  writer_state_ = InternalState::kFinalized;
360}
361
362void EhFrameWriter::GetEhFrame(CodeDesc* desc) {
363  DCHECK(writer_state_ == InternalState::kFinalized);
364  desc->unwinding_info_size = static_cast<int>(eh_frame_buffer_.size());
365  desc->unwinding_info = eh_frame_buffer_.data();
366}
367
368void EhFrameWriter::WriteULeb128(uint32_t value) {
369  do {
370    byte chunk = value & 0x7f;
371    value >>= 7;
372    if (value != 0) chunk |= 0x80;
373    WriteByte(chunk);
374  } while (value != 0);
375}
376
377void EhFrameWriter::WriteSLeb128(int32_t value) {
378  static const int kSignBitMask = 0x40;
379  bool done;
380  do {
381    byte chunk = value & 0x7f;
382    value >>= 7;
383    done = ((value == 0) && ((chunk & kSignBitMask) == 0)) ||
384           ((value == -1) && ((chunk & kSignBitMask) != 0));
385    if (!done) chunk |= 0x80;
386    WriteByte(chunk);
387  } while (!done);
388}
389
390uint32_t EhFrameIterator::GetNextULeb128() {
391  int size = 0;
392  uint32_t result = DecodeULeb128(next_, &size);
393  DCHECK_LE(next_ + size, end_);
394  next_ += size;
395  return result;
396}
397
398int32_t EhFrameIterator::GetNextSLeb128() {
399  int size = 0;
400  int32_t result = DecodeSLeb128(next_, &size);
401  DCHECK_LE(next_ + size, end_);
402  next_ += size;
403  return result;
404}
405
406// static
407uint32_t EhFrameIterator::DecodeULeb128(const byte* encoded,
408                                        int* encoded_size) {
409  const byte* current = encoded;
410  uint32_t result = 0;
411  int shift = 0;
412
413  do {
414    DCHECK_LT(shift, 8 * static_cast<int>(sizeof(result)));
415    result |= (*current & 0x7f) << shift;
416    shift += 7;
417  } while (*current++ >= 128);
418
419  DCHECK_NOT_NULL(encoded_size);
420  *encoded_size = static_cast<int>(current - encoded);
421
422  return result;
423}
424
425// static
426int32_t EhFrameIterator::DecodeSLeb128(const byte* encoded, int* encoded_size) {
427  static const byte kSignBitMask = 0x40;
428
429  const byte* current = encoded;
430  int32_t result = 0;
431  int shift = 0;
432  byte chunk;
433
434  do {
435    chunk = *current++;
436    DCHECK_LT(shift, 8 * static_cast<int>(sizeof(result)));
437    result |= (chunk & 0x7f) << shift;
438    shift += 7;
439  } while (chunk >= 128);
440
441  // Sign extend the result if the last chunk has the sign bit set.
442  if (chunk & kSignBitMask) result |= (~0ull) << shift;
443
444  DCHECK_NOT_NULL(encoded_size);
445  *encoded_size = static_cast<int>(current - encoded);
446
447  return result;
448}
449
450#ifdef ENABLE_DISASSEMBLER
451
452namespace {
453
454class StreamModifiersScope final {
455 public:
456  explicit StreamModifiersScope(std::ostream* stream)
457      : stream_(stream), flags_(stream->flags()) {}
458  ~StreamModifiersScope() { stream_->flags(flags_); }
459
460 private:
461  std::ostream* stream_;
462  std::ios::fmtflags flags_;
463};
464
465}  // namespace
466
467// static
468void EhFrameDisassembler::DumpDwarfDirectives(std::ostream& stream,  // NOLINT
469                                              const byte* start,
470                                              const byte* end) {
471  StreamModifiersScope modifiers_scope(&stream);
472
473  EhFrameIterator eh_frame_iterator(start, end);
474  uint32_t offset_in_procedure = 0;
475
476  while (!eh_frame_iterator.Done()) {
477    stream << eh_frame_iterator.current_address() << "  ";
478
479    byte bytecode = eh_frame_iterator.GetNextByte();
480
481    if (((bytecode >> EhFrameConstants::kLocationMaskSize) & 0xff) ==
482        EhFrameConstants::kLocationTag) {
483      int value = (bytecode & EhFrameConstants::kLocationMask) *
484                  EhFrameConstants::kCodeAlignmentFactor;
485      offset_in_procedure += value;
486      stream << "| pc_offset=" << offset_in_procedure << " (delta=" << value
487             << ")\n";
488      continue;
489    }
490
491    if (((bytecode >> EhFrameConstants::kSavedRegisterMaskSize) & 0xff) ==
492        EhFrameConstants::kSavedRegisterTag) {
493      int32_t decoded_offset = eh_frame_iterator.GetNextULeb128();
494      stream << "| " << DwarfRegisterCodeToString(
495                            bytecode & EhFrameConstants::kLocationMask)
496             << " saved at base" << std::showpos
497             << decoded_offset * EhFrameConstants::kDataAlignmentFactor
498             << std::noshowpos << '\n';
499      continue;
500    }
501
502    if (((bytecode >> EhFrameConstants::kFollowInitialRuleMaskSize) & 0xff) ==
503        EhFrameConstants::kFollowInitialRuleTag) {
504      stream << "| " << DwarfRegisterCodeToString(
505                            bytecode & EhFrameConstants::kLocationMask)
506             << " follows rule in CIE\n";
507      continue;
508    }
509
510    switch (static_cast<EhFrameConstants::DwarfOpcodes>(bytecode)) {
511      case EhFrameConstants::DwarfOpcodes::kOffsetExtendedSf: {
512        stream << "| "
513               << DwarfRegisterCodeToString(eh_frame_iterator.GetNextULeb128());
514        int32_t decoded_offset = eh_frame_iterator.GetNextSLeb128();
515        stream << " saved at base" << std::showpos
516               << decoded_offset * EhFrameConstants::kDataAlignmentFactor
517               << std::noshowpos << '\n';
518        break;
519      }
520      case EhFrameConstants::DwarfOpcodes::kAdvanceLoc1: {
521        int value = eh_frame_iterator.GetNextByte() *
522                    EhFrameConstants::kCodeAlignmentFactor;
523        offset_in_procedure += value;
524        stream << "| pc_offset=" << offset_in_procedure << " (delta=" << value
525               << ")\n";
526        break;
527      }
528      case EhFrameConstants::DwarfOpcodes::kAdvanceLoc2: {
529        int value = eh_frame_iterator.GetNextUInt16() *
530                    EhFrameConstants::kCodeAlignmentFactor;
531        offset_in_procedure += value;
532        stream << "| pc_offset=" << offset_in_procedure << " (delta=" << value
533               << ")\n";
534        break;
535      }
536      case EhFrameConstants::DwarfOpcodes::kAdvanceLoc4: {
537        int value = eh_frame_iterator.GetNextUInt32() *
538                    EhFrameConstants::kCodeAlignmentFactor;
539        offset_in_procedure += value;
540        stream << "| pc_offset=" << offset_in_procedure << " (delta=" << value
541               << ")\n";
542        break;
543      }
544      case EhFrameConstants::DwarfOpcodes::kDefCfa: {
545        uint32_t base_register = eh_frame_iterator.GetNextULeb128();
546        uint32_t base_offset = eh_frame_iterator.GetNextULeb128();
547        stream << "| base_register=" << DwarfRegisterCodeToString(base_register)
548               << ", base_offset=" << base_offset << '\n';
549        break;
550      }
551      case EhFrameConstants::DwarfOpcodes::kDefCfaOffset: {
552        stream << "| base_offset=" << eh_frame_iterator.GetNextULeb128()
553               << '\n';
554        break;
555      }
556      case EhFrameConstants::DwarfOpcodes::kDefCfaRegister: {
557        stream << "| base_register="
558               << DwarfRegisterCodeToString(eh_frame_iterator.GetNextULeb128())
559               << '\n';
560        break;
561      }
562      case EhFrameConstants::DwarfOpcodes::kSameValue: {
563        stream << "| "
564               << DwarfRegisterCodeToString(eh_frame_iterator.GetNextULeb128())
565               << " not modified from previous frame\n";
566        break;
567      }
568      case EhFrameConstants::DwarfOpcodes::kNop:
569        stream << "| nop\n";
570        break;
571      default:
572        UNREACHABLE();
573        return;
574    }
575  }
576}
577
578void EhFrameDisassembler::DisassembleToStream(std::ostream& stream) {  // NOLINT
579  // The encoded CIE size does not include the size field itself.
580  const int cie_size = ReadUnalignedUInt32(start_) + kInt32Size;
581  const int fde_offset = cie_size;
582
583  const byte* cie_directives_start =
584      start_ + EhFrameConstants::kInitialStateOffsetInCie;
585  const byte* cie_directives_end = start_ + cie_size;
586  DCHECK_LE(cie_directives_start, cie_directives_end);
587
588  stream << reinterpret_cast<const void*>(start_) << "  .eh_frame: CIE\n";
589  DumpDwarfDirectives(stream, cie_directives_start, cie_directives_end);
590
591  const byte* procedure_offset_address =
592      start_ + fde_offset + EhFrameConstants::kProcedureAddressOffsetInFde;
593  int32_t procedure_offset =
594      ReadUnalignedValue<int32_t>(procedure_offset_address);
595
596  const byte* procedure_size_address =
597      start_ + fde_offset + EhFrameConstants::kProcedureSizeOffsetInFde;
598  uint32_t procedure_size = ReadUnalignedUInt32(procedure_size_address);
599
600  const byte* fde_start = start_ + fde_offset;
601  stream << reinterpret_cast<const void*>(fde_start) << "  .eh_frame: FDE\n"
602         << reinterpret_cast<const void*>(procedure_offset_address)
603         << "  | procedure_offset=" << procedure_offset << '\n'
604         << reinterpret_cast<const void*>(procedure_size_address)
605         << "  | procedure_size=" << procedure_size << '\n';
606
607  const int fde_directives_offset = fde_offset + 4 * kInt32Size + 1;
608
609  const byte* fde_directives_start = start_ + fde_directives_offset;
610  const byte* fde_directives_end = end_ - EhFrameConstants::kEhFrameHdrSize -
611                                   EhFrameConstants::kEhFrameTerminatorSize;
612  DCHECK_LE(fde_directives_start, fde_directives_end);
613
614  DumpDwarfDirectives(stream, fde_directives_start, fde_directives_end);
615
616  const byte* fde_terminator_start = fde_directives_end;
617  stream << reinterpret_cast<const void*>(fde_terminator_start)
618         << "  .eh_frame: terminator\n";
619
620  const byte* eh_frame_hdr_start =
621      fde_terminator_start + EhFrameConstants::kEhFrameTerminatorSize;
622  stream << reinterpret_cast<const void*>(eh_frame_hdr_start)
623         << "  .eh_frame_hdr\n";
624}
625
626#endif
627
628}  // namespace internal
629}  // namespace v8
630