1 //===- DWARFAcceleratorTable.cpp ------------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h"
11 
12 #include "llvm/ADT/SmallVector.h"
13 #include "llvm/BinaryFormat/Dwarf.h"
14 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
15 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
16 #include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
17 #include "llvm/Support/Compiler.h"
18 #include "llvm/Support/Format.h"
19 #include "llvm/Support/raw_ostream.h"
20 #include <cstddef>
21 #include <cstdint>
22 #include <utility>
23 
24 using namespace llvm;
25 
26 bool DWARFAcceleratorTable::extract() {
27   uint32_t Offset = 0;
28 
29   // Check that we can at least read the header.
30   if (!AccelSection.isValidOffset(offsetof(Header, HeaderDataLength)+4))
31     return false;
32 
33   Hdr.Magic = AccelSection.getU32(&Offset);
34   Hdr.Version = AccelSection.getU16(&Offset);
35   Hdr.HashFunction = AccelSection.getU16(&Offset);
36   Hdr.NumBuckets = AccelSection.getU32(&Offset);
37   Hdr.NumHashes = AccelSection.getU32(&Offset);
38   Hdr.HeaderDataLength = AccelSection.getU32(&Offset);
39 
40   // Check that we can read all the hashes and offsets from the
41   // section (see SourceLevelDebugging.rst for the structure of the index).
42   if (!AccelSection.isValidOffset(sizeof(Hdr) + Hdr.HeaderDataLength +
43                                   Hdr.NumBuckets*4 + Hdr.NumHashes*8))
44     return false;
45 
46   HdrData.DIEOffsetBase = AccelSection.getU32(&Offset);
47   uint32_t NumAtoms = AccelSection.getU32(&Offset);
48 
49   for (unsigned i = 0; i < NumAtoms; ++i) {
50     uint16_t AtomType = AccelSection.getU16(&Offset);
51     auto AtomForm = static_cast<dwarf::Form>(AccelSection.getU16(&Offset));
52     HdrData.Atoms.push_back(std::make_pair(AtomType, AtomForm));
53   }
54 
55   return true;
56 }
57 
58 uint32_t DWARFAcceleratorTable::getNumBuckets() { return Hdr.NumBuckets; }
59 uint32_t DWARFAcceleratorTable::getNumHashes() { return Hdr.NumHashes; }
60 uint32_t DWARFAcceleratorTable::getSizeHdr() { return sizeof(Hdr); }
61 uint32_t DWARFAcceleratorTable::getHeaderDataLength() {
62   return Hdr.HeaderDataLength;
63 }
64 
65 ArrayRef<std::pair<DWARFAcceleratorTable::HeaderData::AtomType,
66                    DWARFAcceleratorTable::HeaderData::Form>>
67 DWARFAcceleratorTable::getAtomsDesc() {
68   return HdrData.Atoms;
69 }
70 
71 bool DWARFAcceleratorTable::validateForms() {
72   for (auto Atom : getAtomsDesc()) {
73     DWARFFormValue FormValue(Atom.second);
74     switch (Atom.first) {
75     case dwarf::DW_ATOM_die_offset:
76       if ((!FormValue.isFormClass(DWARFFormValue::FC_Constant) &&
77            !FormValue.isFormClass(DWARFFormValue::FC_Flag)) ||
78           FormValue.getForm() == dwarf::DW_FORM_sdata)
79         return false;
80     default:
81       break;
82     }
83   }
84   return true;
85 }
86 
87 uint32_t DWARFAcceleratorTable::readAtoms(uint32_t &HashDataOffset) {
88   uint32_t DieOffset = dwarf::DW_INVALID_OFFSET;
89 
90   for (auto Atom : getAtomsDesc()) {
91     DWARFFormValue FormValue(Atom.second);
92     FormValue.extractValue(AccelSection, &HashDataOffset, NULL);
93     switch (Atom.first) {
94     case dwarf::DW_ATOM_die_offset:
95       DieOffset = *FormValue.getAsUnsignedConstant();
96       break;
97     default:
98       break;
99     }
100   }
101   return DieOffset;
102 }
103 
104 LLVM_DUMP_METHOD void DWARFAcceleratorTable::dump(raw_ostream &OS) const {
105   // Dump the header.
106   OS << "Magic = " << format("0x%08x", Hdr.Magic) << '\n'
107      << "Version = " << format("0x%04x", Hdr.Version) << '\n'
108      << "Hash function = " << format("0x%08x", Hdr.HashFunction) << '\n'
109      << "Bucket count = " << Hdr.NumBuckets << '\n'
110      << "Hashes count = " << Hdr.NumHashes << '\n'
111      << "HeaderData length = " << Hdr.HeaderDataLength << '\n'
112      << "DIE offset base = " << HdrData.DIEOffsetBase << '\n'
113      << "Number of atoms = " << HdrData.Atoms.size() << '\n';
114 
115   unsigned i = 0;
116   SmallVector<DWARFFormValue, 3> AtomForms;
117   for (const auto &Atom: HdrData.Atoms) {
118     OS << format("Atom[%d] Type: ", i++);
119     auto TypeString = dwarf::AtomTypeString(Atom.first);
120     if (!TypeString.empty())
121       OS << TypeString;
122     else
123       OS << format("DW_ATOM_Unknown_0x%x", Atom.first);
124     OS << " Form: ";
125     auto FormString = dwarf::FormEncodingString(Atom.second);
126     if (!FormString.empty())
127       OS << FormString;
128     else
129       OS << format("DW_FORM_Unknown_0x%x", Atom.second);
130     OS << '\n';
131     AtomForms.push_back(DWARFFormValue(Atom.second));
132   }
133 
134   // Now go through the actual tables and dump them.
135   uint32_t Offset = sizeof(Hdr) + Hdr.HeaderDataLength;
136   unsigned HashesBase = Offset + Hdr.NumBuckets * 4;
137   unsigned OffsetsBase = HashesBase + Hdr.NumHashes * 4;
138 
139   for (unsigned Bucket = 0; Bucket < Hdr.NumBuckets; ++Bucket) {
140     unsigned Index = AccelSection.getU32(&Offset);
141 
142     OS << format("Bucket[%d]\n", Bucket);
143     if (Index == UINT32_MAX) {
144       OS << "  EMPTY\n";
145       continue;
146     }
147 
148     for (unsigned HashIdx = Index; HashIdx < Hdr.NumHashes; ++HashIdx) {
149       unsigned HashOffset = HashesBase + HashIdx*4;
150       unsigned OffsetsOffset = OffsetsBase + HashIdx*4;
151       uint32_t Hash = AccelSection.getU32(&HashOffset);
152 
153       if (Hash % Hdr.NumBuckets != Bucket)
154         break;
155 
156       unsigned DataOffset = AccelSection.getU32(&OffsetsOffset);
157       OS << format("  Hash = 0x%08x Offset = 0x%08x\n", Hash, DataOffset);
158       if (!AccelSection.isValidOffset(DataOffset)) {
159         OS << "    Invalid section offset\n";
160         continue;
161       }
162       while (AccelSection.isValidOffsetForDataOfSize(DataOffset, 4)) {
163         unsigned StringOffset = AccelSection.getRelocatedValue(4, &DataOffset);
164         if (!StringOffset)
165           break;
166         OS << format("    Name: %08x \"%s\"\n", StringOffset,
167                      StringSection.getCStr(&StringOffset));
168         unsigned NumData = AccelSection.getU32(&DataOffset);
169         for (unsigned Data = 0; Data < NumData; ++Data) {
170           OS << format("    Data[%d] => ", Data);
171           unsigned i = 0;
172           for (auto &Atom : AtomForms) {
173             OS << format("{Atom[%d]: ", i++);
174             if (Atom.extractValue(AccelSection, &DataOffset, nullptr))
175               Atom.dump(OS);
176             else
177               OS << "Error extracting the value";
178             OS << "} ";
179           }
180           OS << '\n';
181         }
182       }
183     }
184   }
185 }
186