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-exception 6 // 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 33 using namespace llvm; 34 using namespace dwarf; 35 36 Expected<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 parsing 53 // 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 72 Expected<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 see 92 // https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html 93 constexpr 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 } 100 101 void 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 } 149 150 void 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 else 158 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 } 177 178 DWARFDebugFrame::DWARFDebugFrame(Triple::ArchType Arch, 179 bool IsEH, uint64_t EHFrameAddress) 180 : Arch(Arch), IsEH(IsEH), EHFrameAddress(EHFrameAddress) {} 181 182 DWARFDebugFrame::~DWARFDebugFrame() = default; 183 184 static void LLVM_ATTRIBUTE_UNUSED dumpDataAux(DataExtractor Data, 185 uint64_t Offset, 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 } 193 194 Error 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 some 207 // dumper tools might need it to print something special for such entries 208 // (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 one 220 // past the end of the structure (needed to know how many instructions to 221 // read). 222 uint64_t StartStructureOffset = Offset; 223 uint64_t EndStructureOffset = Offset + Length; 224 225 // The Id field's size depends on the DWARF format 226 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 CIEs 246 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 if 290 // 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 this 297 // augmentation string 298 break; 299 // This stack frame contains MTE tagged data, so needs to be 300 // 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%" PRIx64 310 " 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 // FDE 327 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%" PRIx64 338 " 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%" PRIx64 367 " 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 } 392 393 FrameEntry *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 } 401 402 void 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