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/ErrorHandling.h"
15 #include "llvm/Support/Format.h"
16 #include "llvm/Support/raw_ostream.h"
21 using namespace dwarf;
24 /// \brief Abstract frame entry defining the common interface concrete
25 /// entries implement.
26 class llvm::FrameEntry {
28 enum FrameKind {FK_CIE, FK_FDE};
29 FrameEntry(FrameKind K, DataExtractor D, uint64_t Offset, uint64_t Length)
30 : Kind(K), Data(D), Offset(Offset), Length(Length) {}
32 virtual ~FrameEntry() {
35 FrameKind getKind() const { return Kind; }
36 virtual uint64_t getOffset() const { return Offset; }
38 /// \brief Parse and store a sequence of CFI instructions from our data
39 /// stream, starting at *Offset and ending at EndOffset. If everything
40 /// goes well, *Offset should be equal to EndOffset when this method
41 /// returns. Otherwise, an error occurred.
42 virtual void parseInstructions(uint32_t *Offset, uint32_t EndOffset);
44 /// \brief Dump the entry header to the given output stream.
45 virtual void dumpHeader(raw_ostream &OS) const = 0;
47 /// \brief Dump the entry's instructions to the given output stream.
48 virtual void dumpInstructions(raw_ostream &OS) const;
53 /// \brief The data stream holding the section from which the entry was
57 /// \brief Offset of this entry in the section.
60 /// \brief Entry length as specified in DWARF.
63 /// An entry may contain CFI instructions. An instruction consists of an
64 /// opcode and an optional sequence of operands.
65 typedef std::vector<uint64_t> Operands;
67 Instruction(uint8_t Opcode)
75 std::vector<Instruction> Instructions;
77 /// Convenience methods to add a new instruction with the given opcode and
78 /// operands to the Instructions vector.
79 void addInstruction(uint8_t Opcode) {
80 Instructions.push_back(Instruction(Opcode));
83 void addInstruction(uint8_t Opcode, uint64_t Operand1) {
84 Instructions.push_back(Instruction(Opcode));
85 Instructions.back().Ops.push_back(Operand1);
88 void addInstruction(uint8_t Opcode, uint64_t Operand1, uint64_t Operand2) {
89 Instructions.push_back(Instruction(Opcode));
90 Instructions.back().Ops.push_back(Operand1);
91 Instructions.back().Ops.push_back(Operand2);
96 // See DWARF standard v3, section 7.23
97 const uint8_t DWARF_CFI_PRIMARY_OPCODE_MASK = 0xc0;
98 const uint8_t DWARF_CFI_PRIMARY_OPERAND_MASK = 0x3f;
101 void FrameEntry::parseInstructions(uint32_t *Offset, uint32_t EndOffset) {
102 while (*Offset < EndOffset) {
103 uint8_t Opcode = Data.getU8(Offset);
104 // Some instructions have a primary opcode encoded in the top bits.
105 uint8_t Primary = Opcode & DWARF_CFI_PRIMARY_OPCODE_MASK;
108 // If it's a primary opcode, the first operand is encoded in the bottom
109 // bits of the opcode itself.
110 uint64_t Op1 = Opcode & DWARF_CFI_PRIMARY_OPERAND_MASK;
112 default: llvm_unreachable("Impossible primary CFI opcode");
113 case DW_CFA_advance_loc:
115 addInstruction(Primary, Op1);
118 addInstruction(Primary, Op1, Data.getULEB128(Offset));
122 // Extended opcode - its value is Opcode itself.
124 default: llvm_unreachable("Invalid extended CFI opcode");
126 case DW_CFA_remember_state:
127 case DW_CFA_restore_state:
129 addInstruction(Opcode);
133 addInstruction(Opcode, Data.getAddress(Offset));
135 case DW_CFA_advance_loc1:
136 // Operands: 1-byte delta
137 addInstruction(Opcode, Data.getU8(Offset));
139 case DW_CFA_advance_loc2:
140 // Operands: 2-byte delta
141 addInstruction(Opcode, Data.getU16(Offset));
143 case DW_CFA_advance_loc4:
144 // Operands: 4-byte delta
145 addInstruction(Opcode, Data.getU32(Offset));
147 case DW_CFA_restore_extended:
148 case DW_CFA_undefined:
149 case DW_CFA_same_value:
150 case DW_CFA_def_cfa_register:
151 case DW_CFA_def_cfa_offset:
153 addInstruction(Opcode, Data.getULEB128(Offset));
155 case DW_CFA_def_cfa_offset_sf:
157 addInstruction(Opcode, Data.getSLEB128(Offset));
159 case DW_CFA_offset_extended:
160 case DW_CFA_register:
162 case DW_CFA_val_offset:
163 // Operands: ULEB128, ULEB128
164 addInstruction(Opcode, Data.getULEB128(Offset),
165 Data.getULEB128(Offset));
167 case DW_CFA_offset_extended_sf:
168 case DW_CFA_def_cfa_sf:
169 case DW_CFA_val_offset_sf:
170 // Operands: ULEB128, SLEB128
171 addInstruction(Opcode, Data.getULEB128(Offset),
172 Data.getSLEB128(Offset));
174 case DW_CFA_def_cfa_expression:
175 case DW_CFA_expression:
176 case DW_CFA_val_expression:
177 // TODO: implement this
178 report_fatal_error("Values with expressions not implemented yet!");
185 void FrameEntry::dumpInstructions(raw_ostream &OS) const {
186 // TODO: at the moment only instruction names are dumped. Expand this to
187 // dump operands as well.
188 for (std::vector<Instruction>::const_iterator I = Instructions.begin(),
189 E = Instructions.end();
191 uint8_t Opcode = I->Opcode;
192 if (Opcode & DWARF_CFI_PRIMARY_OPCODE_MASK)
193 Opcode &= DWARF_CFI_PRIMARY_OPCODE_MASK;
194 OS << " " << CallFrameString(Opcode) << ":\n";
200 /// \brief DWARF Common Information Entry (CIE)
201 class CIE : public FrameEntry {
203 // CIEs (and FDEs) are simply container classes, so the only sensible way to
204 // create them is by providing the full parsed contents in the constructor.
205 CIE(DataExtractor D, uint64_t Offset, uint64_t Length, uint8_t Version,
206 SmallString<8> Augmentation, uint64_t CodeAlignmentFactor,
207 int64_t DataAlignmentFactor, uint64_t ReturnAddressRegister)
208 : FrameEntry(FK_CIE, D, Offset, Length), Version(Version),
209 Augmentation(Augmentation), CodeAlignmentFactor(CodeAlignmentFactor),
210 DataAlignmentFactor(DataAlignmentFactor),
211 ReturnAddressRegister(ReturnAddressRegister) {}
216 void dumpHeader(raw_ostream &OS) const {
217 OS << format("%08x %08x %08x CIE",
218 (uint32_t)Offset, (uint32_t)Length, DW_CIE_ID)
220 OS << format(" Version: %d\n", Version);
221 OS << " Augmentation: \"" << Augmentation << "\"\n";
222 OS << format(" Code alignment factor: %u\n",
223 (uint32_t)CodeAlignmentFactor);
224 OS << format(" Data alignment factor: %d\n",
225 (int32_t)DataAlignmentFactor);
226 OS << format(" Return address column: %d\n",
227 (int32_t)ReturnAddressRegister);
231 static bool classof(const FrameEntry *FE) {
232 return FE->getKind() == FK_CIE;
236 /// The following fields are defined in section 6.4.1 of the DWARF standard v3
238 SmallString<8> Augmentation;
239 uint64_t CodeAlignmentFactor;
240 int64_t DataAlignmentFactor;
241 uint64_t ReturnAddressRegister;
245 /// \brief DWARF Frame Description Entry (FDE)
246 class FDE : public FrameEntry {
248 // Each FDE has a CIE it's "linked to". Our FDE contains is constructed with
249 // an offset to the CIE (provided by parsing the FDE header). The CIE itself
250 // is obtained lazily once it's actually required.
251 FDE(DataExtractor D, uint64_t Offset, uint64_t Length,
252 int64_t LinkedCIEOffset, uint64_t InitialLocation, uint64_t AddressRange)
253 : FrameEntry(FK_FDE, D, Offset, Length), LinkedCIEOffset(LinkedCIEOffset),
254 InitialLocation(InitialLocation), AddressRange(AddressRange),
260 void dumpHeader(raw_ostream &OS) const {
261 OS << format("%08x %08x %08x FDE ",
262 (uint32_t)Offset, (uint32_t)Length, (int32_t)LinkedCIEOffset);
263 OS << format("cie=%08x pc=%08x...%08x\n",
264 (int32_t)LinkedCIEOffset,
265 (uint32_t)InitialLocation,
266 (uint32_t)InitialLocation + (uint32_t)AddressRange);
268 OS << format("%p\n", LinkedCIE);
272 static bool classof(const FrameEntry *FE) {
273 return FE->getKind() == FK_FDE;
277 /// The following fields are defined in section 6.4.1 of the DWARF standard v3
278 uint64_t LinkedCIEOffset;
279 uint64_t InitialLocation;
280 uint64_t AddressRange;
283 } // end anonymous namespace
286 DWARFDebugFrame::DWARFDebugFrame() {
290 DWARFDebugFrame::~DWARFDebugFrame() {
291 for (EntryVector::iterator I = Entries.begin(), E = Entries.end();
298 static void LLVM_ATTRIBUTE_UNUSED dumpDataAux(DataExtractor Data,
299 uint32_t Offset, int Length) {
301 for (int i = 0; i < Length; ++i) {
302 uint8_t c = Data.getU8(&Offset);
303 errs().write_hex(c); errs() << " ";
309 void DWARFDebugFrame::parse(DataExtractor Data) {
312 while (Data.isValidOffset(Offset)) {
313 uint32_t StartOffset = Offset;
315 bool IsDWARF64 = false;
316 uint64_t Length = Data.getU32(&Offset);
319 if (Length == UINT32_MAX) {
320 // DWARF-64 is distinguished by the first 32 bits of the initial length
321 // field being 0xffffffff. Then, the next 64 bits are the actual entry
324 Length = Data.getU64(&Offset);
327 // At this point, Offset points to the next field after Length.
328 // Length is the structure size excluding itself. Compute an offset one
329 // past the end of the structure (needed to know how many instructions to
331 // TODO: For honest DWARF64 support, DataExtractor will have to treat
332 // offset_ptr as uint64_t*
333 uint32_t EndStructureOffset = Offset + static_cast<uint32_t>(Length);
335 // The Id field's size depends on the DWARF format
336 Id = Data.getUnsigned(&Offset, IsDWARF64 ? 8 : 4);
337 bool IsCIE = ((IsDWARF64 && Id == DW64_CIE_ID) || Id == DW_CIE_ID);
339 FrameEntry *Entry = 0;
341 // Note: this is specifically DWARFv3 CIE header structure. It was
342 // changed in DWARFv4. We currently don't support reading DWARFv4
343 // here because LLVM itself does not emit it (and LLDB doesn't
344 // support it either).
345 uint8_t Version = Data.getU8(&Offset);
346 const char *Augmentation = Data.getCStr(&Offset);
347 uint64_t CodeAlignmentFactor = Data.getULEB128(&Offset);
348 int64_t DataAlignmentFactor = Data.getSLEB128(&Offset);
349 uint64_t ReturnAddressRegister = Data.getULEB128(&Offset);
351 Entry = new CIE(Data, StartOffset, Length, Version,
352 StringRef(Augmentation), CodeAlignmentFactor,
353 DataAlignmentFactor, ReturnAddressRegister);
356 uint64_t CIEPointer = Id;
357 uint64_t InitialLocation = Data.getAddress(&Offset);
358 uint64_t AddressRange = Data.getAddress(&Offset);
360 Entry = new FDE(Data, StartOffset, Length, CIEPointer,
361 InitialLocation, AddressRange);
364 assert(Entry && "Expected Entry to be populated with CIE or FDE");
365 Entry->parseInstructions(&Offset, EndStructureOffset);
367 if (Offset == EndStructureOffset) {
368 // Entry instrucitons parsed successfully.
369 Entries.push_back(Entry);
372 raw_string_ostream OS(Str);
373 OS << format("Parsing entry instructions at %lx failed",
375 report_fatal_error(Str);
381 void DWARFDebugFrame::dump(raw_ostream &OS) const {
383 for (EntryVector::const_iterator I = Entries.begin(), E = Entries.end();
385 FrameEntry *Entry = *I;
386 Entry->dumpHeader(OS);
387 Entry->dumpInstructions(OS);