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:
128 case DW_CFA_GNU_window_save:
130 addInstruction(Opcode);
134 addInstruction(Opcode, Data.getAddress(Offset));
136 case DW_CFA_advance_loc1:
137 // Operands: 1-byte delta
138 addInstruction(Opcode, Data.getU8(Offset));
140 case DW_CFA_advance_loc2:
141 // Operands: 2-byte delta
142 addInstruction(Opcode, Data.getU16(Offset));
144 case DW_CFA_advance_loc4:
145 // Operands: 4-byte delta
146 addInstruction(Opcode, Data.getU32(Offset));
148 case DW_CFA_restore_extended:
149 case DW_CFA_undefined:
150 case DW_CFA_same_value:
151 case DW_CFA_def_cfa_register:
152 case DW_CFA_def_cfa_offset:
154 addInstruction(Opcode, Data.getULEB128(Offset));
156 case DW_CFA_def_cfa_offset_sf:
158 addInstruction(Opcode, Data.getSLEB128(Offset));
160 case DW_CFA_offset_extended:
161 case DW_CFA_register:
163 case DW_CFA_val_offset:
164 // Operands: ULEB128, ULEB128
165 addInstruction(Opcode, Data.getULEB128(Offset),
166 Data.getULEB128(Offset));
168 case DW_CFA_offset_extended_sf:
169 case DW_CFA_def_cfa_sf:
170 case DW_CFA_val_offset_sf:
171 // Operands: ULEB128, SLEB128
172 addInstruction(Opcode, Data.getULEB128(Offset),
173 Data.getSLEB128(Offset));
175 case DW_CFA_def_cfa_expression:
176 case DW_CFA_expression:
177 case DW_CFA_val_expression:
178 // TODO: implement this
179 report_fatal_error("Values with expressions not implemented yet!");
186 void FrameEntry::dumpInstructions(raw_ostream &OS) const {
187 // TODO: at the moment only instruction names are dumped. Expand this to
188 // dump operands as well.
189 for (const auto &Instr : Instructions) {
190 uint8_t Opcode = Instr.Opcode;
191 if (Opcode & DWARF_CFI_PRIMARY_OPCODE_MASK)
192 Opcode &= DWARF_CFI_PRIMARY_OPCODE_MASK;
193 OS << " " << CallFrameString(Opcode) << ":\n";
199 /// \brief DWARF Common Information Entry (CIE)
200 class CIE : public FrameEntry {
202 // CIEs (and FDEs) are simply container classes, so the only sensible way to
203 // create them is by providing the full parsed contents in the constructor.
204 CIE(DataExtractor D, uint64_t Offset, uint64_t Length, uint8_t Version,
205 SmallString<8> Augmentation, uint64_t CodeAlignmentFactor,
206 int64_t DataAlignmentFactor, uint64_t ReturnAddressRegister)
207 : FrameEntry(FK_CIE, D, Offset, Length), Version(Version),
208 Augmentation(Augmentation), CodeAlignmentFactor(CodeAlignmentFactor),
209 DataAlignmentFactor(DataAlignmentFactor),
210 ReturnAddressRegister(ReturnAddressRegister) {}
215 void dumpHeader(raw_ostream &OS) const override {
216 OS << format("%08x %08x %08x CIE",
217 (uint32_t)Offset, (uint32_t)Length, DW_CIE_ID)
219 OS << format(" Version: %d\n", Version);
220 OS << " Augmentation: \"" << Augmentation << "\"\n";
221 OS << format(" Code alignment factor: %u\n",
222 (uint32_t)CodeAlignmentFactor);
223 OS << format(" Data alignment factor: %d\n",
224 (int32_t)DataAlignmentFactor);
225 OS << format(" Return address column: %d\n",
226 (int32_t)ReturnAddressRegister);
230 static bool classof(const FrameEntry *FE) {
231 return FE->getKind() == FK_CIE;
235 /// The following fields are defined in section 6.4.1 of the DWARF standard v3
237 SmallString<8> Augmentation;
238 uint64_t CodeAlignmentFactor;
239 int64_t DataAlignmentFactor;
240 uint64_t ReturnAddressRegister;
244 /// \brief DWARF Frame Description Entry (FDE)
245 class FDE : public FrameEntry {
247 // Each FDE has a CIE it's "linked to". Our FDE contains is constructed with
248 // an offset to the CIE (provided by parsing the FDE header). The CIE itself
249 // is obtained lazily once it's actually required.
250 FDE(DataExtractor D, uint64_t Offset, uint64_t Length,
251 int64_t LinkedCIEOffset, uint64_t InitialLocation, uint64_t AddressRange)
252 : FrameEntry(FK_FDE, D, Offset, Length), LinkedCIEOffset(LinkedCIEOffset),
253 InitialLocation(InitialLocation), AddressRange(AddressRange),
259 void dumpHeader(raw_ostream &OS) const override {
260 OS << format("%08x %08x %08x FDE ",
261 (uint32_t)Offset, (uint32_t)Length, (int32_t)LinkedCIEOffset);
262 OS << format("cie=%08x pc=%08x...%08x\n",
263 (int32_t)LinkedCIEOffset,
264 (uint32_t)InitialLocation,
265 (uint32_t)InitialLocation + (uint32_t)AddressRange);
267 OS << format("%p\n", LinkedCIE);
271 static bool classof(const FrameEntry *FE) {
272 return FE->getKind() == FK_FDE;
276 /// The following fields are defined in section 6.4.1 of the DWARF standard v3
277 uint64_t LinkedCIEOffset;
278 uint64_t InitialLocation;
279 uint64_t AddressRange;
282 } // end anonymous namespace
285 DWARFDebugFrame::DWARFDebugFrame() {
289 DWARFDebugFrame::~DWARFDebugFrame() {
290 for (const auto &Entry : Entries) {
296 static void LLVM_ATTRIBUTE_UNUSED dumpDataAux(DataExtractor Data,
297 uint32_t Offset, int Length) {
299 for (int i = 0; i < Length; ++i) {
300 uint8_t c = Data.getU8(&Offset);
301 errs().write_hex(c); errs() << " ";
307 void DWARFDebugFrame::parse(DataExtractor Data) {
310 while (Data.isValidOffset(Offset)) {
311 uint32_t StartOffset = Offset;
313 bool IsDWARF64 = false;
314 uint64_t Length = Data.getU32(&Offset);
317 if (Length == UINT32_MAX) {
318 // DWARF-64 is distinguished by the first 32 bits of the initial length
319 // field being 0xffffffff. Then, the next 64 bits are the actual entry
322 Length = Data.getU64(&Offset);
325 // At this point, Offset points to the next field after Length.
326 // Length is the structure size excluding itself. Compute an offset one
327 // past the end of the structure (needed to know how many instructions to
329 // TODO: For honest DWARF64 support, DataExtractor will have to treat
330 // offset_ptr as uint64_t*
331 uint32_t EndStructureOffset = Offset + static_cast<uint32_t>(Length);
333 // The Id field's size depends on the DWARF format
334 Id = Data.getUnsigned(&Offset, IsDWARF64 ? 8 : 4);
335 bool IsCIE = ((IsDWARF64 && Id == DW64_CIE_ID) || Id == DW_CIE_ID);
337 FrameEntry *Entry = 0;
339 // Note: this is specifically DWARFv3 CIE header structure. It was
340 // changed in DWARFv4. We currently don't support reading DWARFv4
341 // here because LLVM itself does not emit it (and LLDB doesn't
342 // support it either).
343 uint8_t Version = Data.getU8(&Offset);
344 const char *Augmentation = Data.getCStr(&Offset);
345 uint64_t CodeAlignmentFactor = Data.getULEB128(&Offset);
346 int64_t DataAlignmentFactor = Data.getSLEB128(&Offset);
347 uint64_t ReturnAddressRegister = Data.getULEB128(&Offset);
349 Entry = new CIE(Data, StartOffset, Length, Version,
350 StringRef(Augmentation), CodeAlignmentFactor,
351 DataAlignmentFactor, ReturnAddressRegister);
354 uint64_t CIEPointer = Id;
355 uint64_t InitialLocation = Data.getAddress(&Offset);
356 uint64_t AddressRange = Data.getAddress(&Offset);
358 Entry = new FDE(Data, StartOffset, Length, CIEPointer,
359 InitialLocation, AddressRange);
362 assert(Entry && "Expected Entry to be populated with CIE or FDE");
363 Entry->parseInstructions(&Offset, EndStructureOffset);
365 if (Offset == EndStructureOffset) {
366 // Entry instrucitons parsed successfully.
367 Entries.push_back(Entry);
370 raw_string_ostream OS(Str);
371 OS << format("Parsing entry instructions at %lx failed",
373 report_fatal_error(Str);
379 void DWARFDebugFrame::dump(raw_ostream &OS) const {
381 for (const auto &Entry : Entries) {
382 Entry->dumpHeader(OS);
383 Entry->dumpInstructions(OS);