1//===- DWARFDataExtractor.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
9#include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
10#include "llvm/DebugInfo/DWARF/DWARFContext.h"
11
12using namespace llvm;
13
14std::pair<uint64_t, dwarf::DwarfFormat>
15DWARFDataExtractor::getInitialLength(uint64_t *Off, Error *Err) const {
16  ErrorAsOutParameter ErrAsOut(Err);
17  if (Err && *Err)
18    return {0, dwarf::DWARF32};
19
20  Cursor C(*Off);
21  uint64_t Length = getRelocatedValue(C, 4);
22  dwarf::DwarfFormat Format = dwarf::DWARF32;
23  if (Length == dwarf::DW_LENGTH_DWARF64) {
24    Length = getRelocatedValue(C, 8);
25    Format = dwarf::DWARF64;
26  } else if (Length >= dwarf::DW_LENGTH_lo_reserved) {
27    cantFail(C.takeError());
28    if (Err)
29      *Err = createStringError(
30          errc::invalid_argument,
31          "unsupported reserved unit length of value 0x%8.8" PRIx64, Length);
32    return {0, dwarf::DWARF32};
33  }
34
35  if (C) {
36    *Off = C.tell();
37    return {Length, Format};
38  }
39  if (Err)
40    *Err = C.takeError();
41  else
42    consumeError(C.takeError());
43  return {0, dwarf::DWARF32};
44}
45
46uint64_t DWARFDataExtractor::getRelocatedValue(uint32_t Size, uint64_t *Off,
47                                               uint64_t *SecNdx,
48                                               Error *Err) const {
49  if (SecNdx)
50    *SecNdx = object::SectionedAddress::UndefSection;
51  if (!Section)
52    return getUnsigned(Off, Size, Err);
53
54  ErrorAsOutParameter ErrAsOut(Err);
55  Optional<RelocAddrEntry> E = Obj->find(*Section, *Off);
56  uint64_t A = getUnsigned(Off, Size, Err);
57  if (!E || (Err && *Err))
58    return A;
59  if (SecNdx)
60    *SecNdx = E->SectionIndex;
61  uint64_t R = E->Resolver(E->Reloc, E->SymbolValue, A);
62  if (E->Reloc2)
63    R = E->Resolver(*E->Reloc2, E->SymbolValue2, R);
64  return R;
65}
66
67Optional<uint64_t>
68DWARFDataExtractor::getEncodedPointer(uint64_t *Offset, uint8_t Encoding,
69                                      uint64_t PCRelOffset) const {
70  if (Encoding == dwarf::DW_EH_PE_omit)
71    return None;
72
73  uint64_t Result = 0;
74  uint64_t OldOffset = *Offset;
75  // First get value
76  switch (Encoding & 0x0F) {
77  case dwarf::DW_EH_PE_absptr:
78    switch (getAddressSize()) {
79    case 2:
80    case 4:
81    case 8:
82      Result = getUnsigned(Offset, getAddressSize());
83      break;
84    default:
85      return None;
86    }
87    break;
88  case dwarf::DW_EH_PE_uleb128:
89    Result = getULEB128(Offset);
90    break;
91  case dwarf::DW_EH_PE_sleb128:
92    Result = getSLEB128(Offset);
93    break;
94  case dwarf::DW_EH_PE_udata2:
95    Result = getUnsigned(Offset, 2);
96    break;
97  case dwarf::DW_EH_PE_udata4:
98    Result = getUnsigned(Offset, 4);
99    break;
100  case dwarf::DW_EH_PE_udata8:
101    Result = getUnsigned(Offset, 8);
102    break;
103  case dwarf::DW_EH_PE_sdata2:
104    Result = getSigned(Offset, 2);
105    break;
106  case dwarf::DW_EH_PE_sdata4:
107    Result = getSigned(Offset, 4);
108    break;
109  case dwarf::DW_EH_PE_sdata8:
110    Result = getSigned(Offset, 8);
111    break;
112  default:
113    return None;
114  }
115  // Then add relative offset, if required
116  switch (Encoding & 0x70) {
117  case dwarf::DW_EH_PE_absptr:
118    // do nothing
119    break;
120  case dwarf::DW_EH_PE_pcrel:
121    Result += PCRelOffset;
122    break;
123  case dwarf::DW_EH_PE_datarel:
124  case dwarf::DW_EH_PE_textrel:
125  case dwarf::DW_EH_PE_funcrel:
126  case dwarf::DW_EH_PE_aligned:
127  default:
128    *Offset = OldOffset;
129    return None;
130  }
131
132  return Result;
133}
134