415 lines · cpp
1//===- DWARFDebugFrame.h - Parsing of .debug_frame ------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "llvm/DebugInfo/DWARF/DWARFDebugFrame.h"10#include "llvm/ADT/DenseMap.h"11#include "llvm/ADT/StringExtras.h"12#include "llvm/ADT/StringRef.h"13#include "llvm/BinaryFormat/Dwarf.h"14#include "llvm/DebugInfo/DIContext.h"15#include "llvm/DebugInfo/DWARF/DWARFCFIPrinter.h"16#include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"17#include "llvm/DebugInfo/DWARF/DWARFExpressionPrinter.h"18#include "llvm/DebugInfo/DWARF/DWARFUnwindTablePrinter.h"19#include "llvm/DebugInfo/DWARF/LowLevel/DWARFCFIProgram.h"20#include "llvm/DebugInfo/DWARF/LowLevel/DWARFExpression.h"21#include "llvm/Support/Compiler.h"22#include "llvm/Support/DataExtractor.h"23#include "llvm/Support/Errc.h"24#include "llvm/Support/Error.h"25#include "llvm/Support/ErrorHandling.h"26#include "llvm/Support/Format.h"27#include "llvm/Support/raw_ostream.h"28#include <cassert>29#include <cinttypes>30#include <cstdint>31#include <optional>32 33using namespace llvm;34using namespace dwarf;35 36Expected<UnwindTable> llvm::dwarf::createUnwindTable(const FDE *Fde) {37 const CIE *Cie = Fde->getLinkedCIE();38 if (Cie == nullptr)39 return createStringError(errc::invalid_argument,40 "unable to get CIE for FDE at offset 0x%" PRIx64,41 Fde->getOffset());42 43 // Rows will be empty if there are no CFI instructions.44 if (Cie->cfis().empty() && Fde->cfis().empty())45 return UnwindTable({});46 47 UnwindTable::RowContainer CieRows;48 UnwindRow Row;49 Row.setAddress(Fde->getInitialLocation());50 if (Error CieError = parseRows(Cie->cfis(), Row, nullptr).moveInto(CieRows))51 return std::move(CieError);52 // We need to save the initial locations of registers from the CIE parsing53 // in case we run into DW_CFA_restore or DW_CFA_restore_extended opcodes.54 UnwindTable::RowContainer FdeRows;55 const RegisterLocations InitialLocs = Row.getRegisterLocations();56 if (Error FdeError =57 parseRows(Fde->cfis(), Row, &InitialLocs).moveInto(FdeRows))58 return std::move(FdeError);59 60 UnwindTable::RowContainer AllRows;61 AllRows.insert(AllRows.end(), CieRows.begin(), CieRows.end());62 AllRows.insert(AllRows.end(), FdeRows.begin(), FdeRows.end());63 64 // May be all the CFI instructions were DW_CFA_nop amd Row becomes empty.65 // Do not add that to the unwind table.66 if (Row.getRegisterLocations().hasLocations() ||67 Row.getCFAValue().getLocation() != UnwindLocation::Unspecified)68 AllRows.push_back(Row);69 return UnwindTable(std::move(AllRows));70}71 72Expected<UnwindTable> llvm::dwarf::createUnwindTable(const CIE *Cie) {73 // Rows will be empty if there are no CFI instructions.74 if (Cie->cfis().empty())75 return UnwindTable({});76 77 UnwindTable::RowContainer Rows;78 UnwindRow Row;79 if (Error CieError = parseRows(Cie->cfis(), Row, nullptr).moveInto(Rows))80 return std::move(CieError);81 // May be all the CFI instructions were DW_CFA_nop amd Row becomes empty.82 // Do not add that to the unwind table.83 if (Row.getRegisterLocations().hasLocations() ||84 Row.getCFAValue().getLocation() != UnwindLocation::Unspecified)85 Rows.push_back(Row);86 return UnwindTable(std::move(Rows));87}88 89// Returns the CIE identifier to be used by the requested format.90// CIE ids for .debug_frame sections are defined in Section 7.24 of DWARFv5.91// For CIE ID in .eh_frame sections see92// https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html93constexpr uint64_t getCIEId(bool IsDWARF64, bool IsEH) {94 if (IsEH)95 return 0;96 if (IsDWARF64)97 return DW64_CIE_ID;98 return DW_CIE_ID;99}100 101void CIE::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {102 // A CIE with a zero length is a terminator entry in the .eh_frame section.103 if (DumpOpts.IsEH && Length == 0) {104 OS << format("%08" PRIx64, Offset) << " ZERO terminator\n";105 return;106 }107 108 OS << format("%08" PRIx64, Offset)109 << format(" %0*" PRIx64, IsDWARF64 ? 16 : 8, Length)110 << format(" %0*" PRIx64, IsDWARF64 && !DumpOpts.IsEH ? 16 : 8,111 getCIEId(IsDWARF64, DumpOpts.IsEH))112 << " CIE\n"113 << " Format: " << FormatString(IsDWARF64) << "\n";114 if (DumpOpts.IsEH && Version != 1)115 OS << "WARNING: unsupported CIE version\n";116 OS << format(" Version: %d\n", Version)117 << " Augmentation: \"" << Augmentation << "\"\n";118 if (Version >= 4) {119 OS << format(" Address size: %u\n", (uint32_t)AddressSize);120 OS << format(" Segment desc size: %u\n",121 (uint32_t)SegmentDescriptorSize);122 }123 OS << format(" Code alignment factor: %u\n", (uint32_t)CodeAlignmentFactor);124 OS << format(" Data alignment factor: %d\n", (int32_t)DataAlignmentFactor);125 OS << format(" Return address column: %d\n", (int32_t)ReturnAddressRegister);126 if (Personality)127 OS << format(" Personality Address: %016" PRIx64 "\n", *Personality);128 if (!AugmentationData.empty()) {129 OS << " Augmentation data: ";130 for (uint8_t Byte : AugmentationData)131 OS << ' ' << hexdigit(Byte >> 4) << hexdigit(Byte & 0xf);132 OS << "\n";133 }134 OS << "\n";135 printCFIProgram(CFIs, OS, DumpOpts, /*IndentLevel=*/1,136 /*InitialLocation=*/{});137 OS << "\n";138 139 if (Expected<UnwindTable> RowsOrErr = createUnwindTable(this))140 printUnwindTable(*RowsOrErr, OS, DumpOpts, 1);141 else {142 DumpOpts.RecoverableErrorHandler(joinErrors(143 createStringError(errc::invalid_argument,144 "decoding the CIE opcodes into rows failed"),145 RowsOrErr.takeError()));146 }147 OS << "\n";148}149 150void FDE::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {151 OS << format("%08" PRIx64, Offset)152 << format(" %0*" PRIx64, IsDWARF64 ? 16 : 8, Length)153 << format(" %0*" PRIx64, IsDWARF64 && !DumpOpts.IsEH ? 16 : 8, CIEPointer)154 << " FDE cie=";155 if (LinkedCIE)156 OS << format("%08" PRIx64, LinkedCIE->getOffset());157 else158 OS << "<invalid offset>";159 OS << format(" pc=%08" PRIx64 "...%08" PRIx64 "\n", InitialLocation,160 InitialLocation + AddressRange);161 OS << " Format: " << FormatString(IsDWARF64) << "\n";162 if (LSDAAddress)163 OS << format(" LSDA Address: %016" PRIx64 "\n", *LSDAAddress);164 printCFIProgram(CFIs, OS, DumpOpts, /*IndentLevel=*/1, InitialLocation);165 OS << "\n";166 167 if (Expected<UnwindTable> RowsOrErr = createUnwindTable(this))168 printUnwindTable(*RowsOrErr, OS, DumpOpts, 1);169 else {170 DumpOpts.RecoverableErrorHandler(joinErrors(171 createStringError(errc::invalid_argument,172 "decoding the FDE opcodes into rows failed"),173 RowsOrErr.takeError()));174 }175 OS << "\n";176}177 178DWARFDebugFrame::DWARFDebugFrame(Triple::ArchType Arch,179 bool IsEH, uint64_t EHFrameAddress)180 : Arch(Arch), IsEH(IsEH), EHFrameAddress(EHFrameAddress) {}181 182DWARFDebugFrame::~DWARFDebugFrame() = default;183 184[[maybe_unused]] static void dumpDataAux(DataExtractor Data, uint64_t Offset,185 int Length) {186 errs() << "DUMP: ";187 for (int i = 0; i < Length; ++i) {188 uint8_t c = Data.getU8(&Offset);189 errs().write_hex(c); errs() << " ";190 }191 errs() << "\n";192}193 194Error DWARFDebugFrame::parse(DWARFDataExtractor Data) {195 uint64_t Offset = 0;196 DenseMap<uint64_t, CIE *> CIEs;197 198 while (Data.isValidOffset(Offset)) {199 uint64_t StartOffset = Offset;200 201 uint64_t Length;202 DwarfFormat Format;203 std::tie(Length, Format) = Data.getInitialLength(&Offset);204 bool IsDWARF64 = Format == DWARF64;205 206 // If the Length is 0, then this CIE is a terminator. We add it because some207 // dumper tools might need it to print something special for such entries208 // (e.g. llvm-objdump --dwarf=frames prints "ZERO terminator").209 if (Length == 0) {210 auto Cie = std::make_unique<CIE>(211 IsDWARF64, StartOffset, 0, 0, SmallString<8>(), 0, 0, 0, 0, 0,212 SmallString<8>(), 0, 0, std::nullopt, std::nullopt, Arch);213 CIEs[StartOffset] = Cie.get();214 Entries.push_back(std::move(Cie));215 break;216 }217 218 // At this point, Offset points to the next field after Length.219 // Length is the structure size excluding itself. Compute an offset one220 // past the end of the structure (needed to know how many instructions to221 // read).222 uint64_t StartStructureOffset = Offset;223 uint64_t EndStructureOffset = Offset + Length;224 225 // The Id field's size depends on the DWARF format226 Error Err = Error::success();227 uint64_t Id = Data.getRelocatedValue((IsDWARF64 && !IsEH) ? 8 : 4, &Offset,228 /*SectionIndex=*/nullptr, &Err);229 if (Err)230 return Err;231 232 if (Id == getCIEId(IsDWARF64, IsEH)) {233 uint8_t Version = Data.getU8(&Offset);234 const char *Augmentation = Data.getCStr(&Offset);235 StringRef AugmentationString(Augmentation ? Augmentation : "");236 uint8_t AddressSize = Version < 4 ? Data.getAddressSize() :237 Data.getU8(&Offset);238 Data.setAddressSize(AddressSize);239 uint8_t SegmentDescriptorSize = Version < 4 ? 0 : Data.getU8(&Offset);240 uint64_t CodeAlignmentFactor = Data.getULEB128(&Offset);241 int64_t DataAlignmentFactor = Data.getSLEB128(&Offset);242 uint64_t ReturnAddressRegister =243 Version == 1 ? Data.getU8(&Offset) : Data.getULEB128(&Offset);244 245 // Parse the augmentation data for EH CIEs246 StringRef AugmentationData("");247 uint32_t FDEPointerEncoding = DW_EH_PE_absptr;248 uint32_t LSDAPointerEncoding = DW_EH_PE_omit;249 std::optional<uint64_t> Personality;250 std::optional<uint32_t> PersonalityEncoding;251 if (IsEH) {252 std::optional<uint64_t> AugmentationLength;253 uint64_t StartAugmentationOffset;254 uint64_t EndAugmentationOffset;255 256 // Walk the augmentation string to get all the augmentation data.257 for (unsigned i = 0, e = AugmentationString.size(); i != e; ++i) {258 switch (AugmentationString[i]) {259 default:260 return createStringError(261 errc::invalid_argument,262 "unknown augmentation character %c in entry at 0x%" PRIx64,263 AugmentationString[i], StartOffset);264 case 'L':265 LSDAPointerEncoding = Data.getU8(&Offset);266 break;267 case 'P': {268 if (Personality)269 return createStringError(270 errc::invalid_argument,271 "duplicate personality in entry at 0x%" PRIx64, StartOffset);272 PersonalityEncoding = Data.getU8(&Offset);273 Personality = Data.getEncodedPointer(274 &Offset, *PersonalityEncoding,275 EHFrameAddress ? EHFrameAddress + Offset : 0);276 break;277 }278 case 'R':279 FDEPointerEncoding = Data.getU8(&Offset);280 break;281 case 'S':282 // Current frame is a signal trampoline.283 break;284 case 'z':285 if (i)286 return createStringError(287 errc::invalid_argument,288 "'z' must be the first character at 0x%" PRIx64, StartOffset);289 // Parse the augmentation length first. We only parse it if290 // the string contains a 'z'.291 AugmentationLength = Data.getULEB128(&Offset);292 StartAugmentationOffset = Offset;293 EndAugmentationOffset = Offset + *AugmentationLength;294 break;295 case 'B':296 // B-Key is used for signing functions associated with this297 // augmentation string298 break;299 // This stack frame contains MTE tagged data, so needs to be300 // untagged on unwind.301 case 'G':302 break;303 }304 }305 306 if (AugmentationLength) {307 if (Offset != EndAugmentationOffset)308 return createStringError(errc::invalid_argument,309 "parsing augmentation data at 0x%" PRIx64310 " failed",311 StartOffset);312 AugmentationData = Data.getData().slice(StartAugmentationOffset,313 EndAugmentationOffset);314 }315 }316 317 auto Cie = std::make_unique<CIE>(318 IsDWARF64, StartOffset, Length, Version, AugmentationString,319 AddressSize, SegmentDescriptorSize, CodeAlignmentFactor,320 DataAlignmentFactor, ReturnAddressRegister, AugmentationData,321 FDEPointerEncoding, LSDAPointerEncoding, Personality,322 PersonalityEncoding, Arch);323 CIEs[StartOffset] = Cie.get();324 Entries.emplace_back(std::move(Cie));325 } else {326 // FDE327 uint64_t CIEPointer = Id;328 uint64_t InitialLocation = 0;329 uint64_t AddressRange = 0;330 std::optional<uint64_t> LSDAAddress;331 CIE *Cie = CIEs[IsEH ? (StartStructureOffset - CIEPointer) : CIEPointer];332 333 if (IsEH) {334 // The address size is encoded in the CIE we reference.335 if (!Cie)336 return createStringError(errc::invalid_argument,337 "parsing FDE data at 0x%" PRIx64338 " failed due to missing CIE",339 StartOffset);340 if (auto Val =341 Data.getEncodedPointer(&Offset, Cie->getFDEPointerEncoding(),342 EHFrameAddress + Offset)) {343 InitialLocation = *Val;344 }345 if (auto Val = Data.getEncodedPointer(346 &Offset, Cie->getFDEPointerEncoding(), 0)) {347 AddressRange = *Val;348 }349 350 StringRef AugmentationString = Cie->getAugmentationString();351 if (!AugmentationString.empty()) {352 // Parse the augmentation length and data for this FDE.353 uint64_t AugmentationLength = Data.getULEB128(&Offset);354 355 uint64_t EndAugmentationOffset = Offset + AugmentationLength;356 357 // Decode the LSDA if the CIE augmentation string said we should.358 if (Cie->getLSDAPointerEncoding() != DW_EH_PE_omit) {359 LSDAAddress = Data.getEncodedPointer(360 &Offset, Cie->getLSDAPointerEncoding(),361 EHFrameAddress ? Offset + EHFrameAddress : 0);362 }363 364 if (Offset != EndAugmentationOffset)365 return createStringError(errc::invalid_argument,366 "parsing augmentation data at 0x%" PRIx64367 " failed",368 StartOffset);369 }370 } else {371 InitialLocation = Data.getRelocatedAddress(&Offset);372 AddressRange = Data.getRelocatedAddress(&Offset);373 }374 375 Entries.emplace_back(new FDE(IsDWARF64, StartOffset, Length, CIEPointer,376 InitialLocation, AddressRange, Cie,377 LSDAAddress, Arch));378 }379 380 if (Error E =381 Entries.back()->cfis().parse(Data, &Offset, EndStructureOffset))382 return E;383 384 if (Offset != EndStructureOffset)385 return createStringError(386 errc::invalid_argument,387 "parsing entry instructions at 0x%" PRIx64 " failed", StartOffset);388 }389 390 return Error::success();391}392 393FrameEntry *DWARFDebugFrame::getEntryAtOffset(uint64_t Offset) const {394 auto It = partition_point(Entries, [=](const std::unique_ptr<FrameEntry> &E) {395 return E->getOffset() < Offset;396 });397 if (It != Entries.end() && (*It)->getOffset() == Offset)398 return It->get();399 return nullptr;400}401 402void DWARFDebugFrame::dump(raw_ostream &OS, DIDumpOptions DumpOpts,403 std::optional<uint64_t> Offset) const {404 DumpOpts.IsEH = IsEH;405 if (Offset) {406 if (auto *Entry = getEntryAtOffset(*Offset))407 Entry->dump(OS, DumpOpts);408 return;409 }410 411 OS << "\n";412 for (const auto &Entry : Entries)413 Entry->dump(OS, DumpOpts);414}415