1 //===-- DWARFDebugFrame.h - Parsing of .debug_frame -------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "DWARFDebugFrame.h"
11 #include "llvm/ADT/SmallString.h"
12 #include "llvm/Support/DataTypes.h"
13 #include "llvm/Support/Dwarf.h"
14 #include "llvm/Support/Format.h"
17 using namespace dwarf;
20 class llvm::FrameEntry {
22 enum FrameKind {FK_CIE, FK_FDE};
23 FrameEntry(FrameKind K, DataExtractor D, uint64_t Offset, uint64_t Length)
24 : Kind(K), Data(D), Offset(Offset), Length(Length) {}
26 virtual ~FrameEntry() {
29 FrameKind getKind() const { return Kind; }
31 virtual void dumpHeader(raw_ostream &OS) const = 0;
36 /// \brief The data stream holding the section from which the entry was
40 /// \brief Offset of this entry in the section.
43 /// \brief Entry length as specified in DWARF.
48 class CIE : public FrameEntry {
50 // CIEs (and FDEs) are simply container classes, so the only sensible way to
51 // create them is by providing the full parsed contents in the constructor.
52 CIE(DataExtractor D, uint64_t Offset, uint64_t Length, uint8_t Version,
53 SmallString<8> Augmentation, uint64_t CodeAlignmentFactor,
54 int64_t DataAlignmentFactor, uint64_t ReturnAddressRegister)
55 : FrameEntry(FK_CIE, D, Offset, Length), Version(Version),
56 Augmentation(Augmentation), CodeAlignmentFactor(CodeAlignmentFactor),
57 DataAlignmentFactor(DataAlignmentFactor),
58 ReturnAddressRegister(ReturnAddressRegister) {}
63 void dumpHeader(raw_ostream &OS) const {
64 OS << format("%08x %08x %08x CIE", Offset, Length, DW_CIE_ID) << "\n";
65 OS << format(" Version: %d\n", Version);
66 OS << " Augmentation: \"" << Augmentation << "\"\n";
67 OS << format(" Code alignment factor: %u\n", CodeAlignmentFactor);
68 OS << format(" Data alignment factor: %d\n", DataAlignmentFactor);
69 OS << format(" Return address column: %d\n", ReturnAddressRegister);
73 static bool classof(const FrameEntry *FE) {
74 return FE->getKind() == FK_CIE;
78 /// The following fields are defined in section 6.4.1 of the DWARF standard v3
80 SmallString<8> Augmentation;
81 uint64_t CodeAlignmentFactor;
82 int64_t DataAlignmentFactor;
83 uint64_t ReturnAddressRegister;
87 class FDE : public FrameEntry {
89 // Each FDE has a CIE it's "linked to". Our FDE contains is constructed with
90 // an offset to the CIE (provided by parsing the FDE header). The CIE itself
91 // is obtained lazily once it's actually required.
92 FDE(DataExtractor D, uint64_t Offset, uint64_t Length,
93 int64_t LinkedCIEOffset, uint64_t InitialLocation, uint64_t AddressRange)
94 : FrameEntry(FK_FDE, D, Offset, Length), LinkedCIEOffset(LinkedCIEOffset),
95 InitialLocation(InitialLocation), AddressRange(AddressRange),
101 void dumpHeader(raw_ostream &OS) const {
102 OS << format("%08x %08x %08x FDE ", Offset, Length, LinkedCIEOffset);
103 OS << format("cie=%08x pc=%08x...%08x\n",
104 LinkedCIEOffset, InitialLocation,
105 InitialLocation + AddressRange);
109 static bool classof(const FrameEntry *FE) {
110 return FE->getKind() == FK_FDE;
114 /// The following fields are defined in section 6.4.1 of the DWARF standard v3
115 uint64_t LinkedCIEOffset;
116 uint64_t InitialLocation;
117 uint64_t AddressRange;
122 DWARFDebugFrame::DWARFDebugFrame() {
126 DWARFDebugFrame::~DWARFDebugFrame() {
127 for (EntryVector::iterator I = Entries.begin(), E = Entries.end();
134 static void LLVM_ATTRIBUTE_UNUSED dumpDataAux(DataExtractor Data,
135 uint32_t Offset, int Length) {
137 for (int i = 0; i < Length; ++i) {
138 uint8_t c = Data.getU8(&Offset);
139 errs().write_hex(c); errs() << " ";
145 void DWARFDebugFrame::parse(DataExtractor Data) {
148 while (Data.isValidOffset(Offset)) {
149 uint32_t StartOffset = Offset;
151 bool IsDWARF64 = false;
152 uint64_t Length = Data.getU32(&Offset);
155 if (Length == UINT32_MAX) {
156 // DWARF-64 is distinguished by the first 32 bits of the initial length
157 // field being 0xffffffff. Then, the next 64 bits are the actual entry
160 Length = Data.getU64(&Offset);
163 // At this point, Offset points to the next field after Length.
164 // Length is the structure size excluding itself. Compute an offset one
165 // past the end of the structure (needed to know how many instructions to
167 // TODO: For honest DWARF64 support, DataExtractor will have to treat
168 // offset_ptr as uint64_t*
169 uint32_t EndStructureOffset = Offset + static_cast<uint32_t>(Length);
171 // The Id field's size depends on the DWARF format
172 Id = Data.getUnsigned(&Offset, IsDWARF64 ? 8 : 4);
173 bool IsCIE = ((IsDWARF64 && Id == DW64_CIE_ID) || Id == DW_CIE_ID);
176 // Note: this is specifically DWARFv3 CIE header structure. It was
177 // changed in DWARFv4.
178 uint8_t Version = Data.getU8(&Offset);
179 const char *Augmentation = Data.getCStr(&Offset);
180 uint64_t CodeAlignmentFactor = Data.getULEB128(&Offset);
181 int64_t DataAlignmentFactor = Data.getSLEB128(&Offset);
182 uint64_t ReturnAddressRegister = Data.getULEB128(&Offset);
184 CIE *NewCIE = new CIE(Data, StartOffset, Length, Version,
185 StringRef(Augmentation), CodeAlignmentFactor,
186 DataAlignmentFactor, ReturnAddressRegister);
187 Entries.push_back(NewCIE);
190 uint64_t CIEPointer = Id;
191 uint64_t InitialLocation = Data.getAddress(&Offset);
192 uint64_t AddressRange = Data.getAddress(&Offset);
194 FDE *NewFDE = new FDE(Data, StartOffset, Length, CIEPointer,
195 InitialLocation, AddressRange);
196 Entries.push_back(NewFDE);
199 Offset = EndStructureOffset;
204 void DWARFDebugFrame::dump(raw_ostream &OS) const {
206 for (EntryVector::const_iterator I = Entries.begin(), E = Entries.end();
208 (*I)->dumpHeader(OS);