DWARFDebugFrame.cpp revision 8a0329e6ffc290fb177fd058a64b4cf81d4b620a
1//===-- DWARFDebugFrame.h - Parsing of .debug_frame -------------*- C++ -*-===// 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 "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" 15 16using namespace llvm; 17using namespace dwarf; 18 19 20class llvm::FrameEntry { 21public: 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) {} 25 26 virtual ~FrameEntry() { 27 } 28 29 FrameKind getKind() const { return Kind; } 30 31 virtual void dumpHeader(raw_ostream &OS) const = 0; 32 33protected: 34 const FrameKind Kind; 35 36 /// \brief The data stream holding the section from which the entry was 37 /// parsed. 38 DataExtractor Data; 39 40 /// \brief Offset of this entry in the section. 41 uint64_t Offset; 42 43 /// \brief Entry length as specified in DWARF. 44 uint64_t Length; 45}; 46 47 48class CIE : public FrameEntry { 49public: 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) {} 59 60 ~CIE() { 61 } 62 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); 70 OS << "\n"; 71 } 72 73 static bool classof(const FrameEntry *FE) { 74 return FE->getKind() == FK_CIE; 75 } 76 77private: 78 /// The following fields are defined in section 6.4.1 of the DWARF standard v3 79 uint8_t Version; 80 SmallString<8> Augmentation; 81 uint64_t CodeAlignmentFactor; 82 int64_t DataAlignmentFactor; 83 uint64_t ReturnAddressRegister; 84}; 85 86 87class FDE : public FrameEntry { 88public: 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), 96 LinkedCIE(NULL) {} 97 98 ~FDE() { 99 } 100 101 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); 106 OS << "\n"; 107 } 108 109 static bool classof(const FrameEntry *FE) { 110 return FE->getKind() == FK_FDE; 111 } 112private: 113 114 /// 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; 118 CIE *LinkedCIE; 119}; 120 121 122DWARFDebugFrame::DWARFDebugFrame() { 123} 124 125 126DWARFDebugFrame::~DWARFDebugFrame() { 127 for (EntryVector::iterator I = Entries.begin(), E = Entries.end(); 128 I != E; ++I) { 129 delete *I; 130 } 131} 132 133 134static void LLVM_ATTRIBUTE_UNUSED dumpDataAux(DataExtractor Data, 135 uint32_t Offset, int Length) { 136 errs() << "DUMP: "; 137 for (int i = 0; i < Length; ++i) { 138 uint8_t c = Data.getU8(&Offset); 139 errs().write_hex(c); errs() << " "; 140 } 141 errs() << "\n"; 142} 143 144 145void DWARFDebugFrame::parse(DataExtractor Data) { 146 uint32_t Offset = 0; 147 148 while (Data.isValidOffset(Offset)) { 149 uint32_t StartOffset = Offset; 150 151 bool IsDWARF64 = false; 152 uint64_t Length = Data.getU32(&Offset); 153 uint64_t Id; 154 155 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 158 // length. 159 IsDWARF64 = true; 160 Length = Data.getU64(&Offset); 161 } 162 163 // 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 166 // read). 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); 170 171 // 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); 174 175 if (IsCIE) { 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); 183 184 CIE *NewCIE = new CIE(Data, StartOffset, Length, Version, 185 StringRef(Augmentation), CodeAlignmentFactor, 186 DataAlignmentFactor, ReturnAddressRegister); 187 Entries.push_back(NewCIE); 188 } else { 189 // FDE 190 uint64_t CIEPointer = Id; 191 uint64_t InitialLocation = Data.getAddress(&Offset); 192 uint64_t AddressRange = Data.getAddress(&Offset); 193 194 FDE *NewFDE = new FDE(Data, StartOffset, Length, CIEPointer, 195 InitialLocation, AddressRange); 196 Entries.push_back(NewFDE); 197 } 198 199 Offset = EndStructureOffset; 200 } 201} 202 203 204void DWARFDebugFrame::dump(raw_ostream &OS) const { 205 OS << "\n"; 206 for (EntryVector::const_iterator I = Entries.begin(), E = Entries.end(); 207 I != E; ++I) { 208 (*I)->dumpHeader(OS); 209 } 210} 211 212