1 //===- ELF.h - ELF object file implementation -------------------*- C++ -*-===// 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 // This file declares the ELFFile template class. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_OBJECT_ELF_H 14 #define LLVM_OBJECT_ELF_H 15 16 #include "llvm/ADT/ArrayRef.h" 17 #include "llvm/ADT/MapVector.h" 18 #include "llvm/ADT/SmallString.h" 19 #include "llvm/ADT/SmallVector.h" 20 #include "llvm/ADT/StringRef.h" 21 #include "llvm/BinaryFormat/ELF.h" 22 #include "llvm/Object/ELFTypes.h" 23 #include "llvm/Object/Error.h" 24 #include "llvm/Support/Error.h" 25 #include <cassert> 26 #include <cstddef> 27 #include <cstdint> 28 #include <limits> 29 #include <utility> 30 31 namespace llvm { 32 namespace object { 33 34 struct VerdAux { 35 unsigned Offset; 36 std::string Name; 37 }; 38 39 struct VerDef { 40 unsigned Offset; 41 unsigned Version; 42 unsigned Flags; 43 unsigned Ndx; 44 unsigned Cnt; 45 unsigned Hash; 46 std::string Name; 47 std::vector<VerdAux> AuxV; 48 }; 49 50 struct VernAux { 51 unsigned Hash; 52 unsigned Flags; 53 unsigned Other; 54 unsigned Offset; 55 std::string Name; 56 }; 57 58 struct VerNeed { 59 unsigned Version; 60 unsigned Cnt; 61 unsigned Offset; 62 std::string File; 63 std::vector<VernAux> AuxV; 64 }; 65 66 struct VersionEntry { 67 std::string Name; 68 bool IsVerDef; 69 }; 70 71 StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type); 72 uint32_t getELFRelativeRelocationType(uint32_t Machine); 73 StringRef getELFSectionTypeName(uint32_t Machine, uint32_t Type); 74 75 // Subclasses of ELFFile may need this for template instantiation 76 inline std::pair<unsigned char, unsigned char> 77 getElfArchType(StringRef Object) { 78 if (Object.size() < ELF::EI_NIDENT) 79 return std::make_pair((uint8_t)ELF::ELFCLASSNONE, 80 (uint8_t)ELF::ELFDATANONE); 81 return std::make_pair((uint8_t)Object[ELF::EI_CLASS], 82 (uint8_t)Object[ELF::EI_DATA]); 83 } 84 85 enum PPCInstrMasks : uint64_t { 86 PADDI_R12_NO_DISP = 0x0610000039800000, 87 ADDIS_R12_TO_R2_NO_DISP = 0x3D820000, 88 ADDI_R12_TO_R2_NO_DISP = 0x39820000, 89 ADDI_R12_TO_R12_NO_DISP = 0x398C0000, 90 PLD_R12_NO_DISP = 0x04100000E5800000, 91 MTCTR_R12 = 0x7D8903A6, 92 BCTR = 0x4E800420, 93 }; 94 95 template <class ELFT> class ELFFile; 96 97 template <class T> struct DataRegion { 98 // This constructor is used when we know the start and the size of a data 99 // region. We assume that Arr does not go past the end of the file. 100 DataRegion(ArrayRef<T> Arr) : First(Arr.data()), Size(Arr.size()) {} 101 102 // Sometimes we only know the start of a data region. We still don't want to 103 // read past the end of the file, so we provide the end of a buffer. 104 DataRegion(const T *Data, const uint8_t *BufferEnd) 105 : First(Data), BufEnd(BufferEnd) {} 106 107 Expected<T> operator[](uint64_t N) { 108 assert(Size || BufEnd); 109 if (Size) { 110 if (N >= *Size) 111 return createError( 112 "the index is greater than or equal to the number of entries (" + 113 Twine(*Size) + ")"); 114 } else { 115 const uint8_t *EntryStart = (const uint8_t *)First + N * sizeof(T); 116 if (EntryStart + sizeof(T) > BufEnd) 117 return createError("can't read past the end of the file"); 118 } 119 return *(First + N); 120 } 121 122 const T *First; 123 std::optional<uint64_t> Size; 124 const uint8_t *BufEnd = nullptr; 125 }; 126 127 template <class ELFT> 128 std::string getSecIndexForError(const ELFFile<ELFT> &Obj, 129 const typename ELFT::Shdr &Sec) { 130 auto TableOrErr = Obj.sections(); 131 if (TableOrErr) 132 return "[index " + std::to_string(&Sec - &TableOrErr->front()) + "]"; 133 // To make this helper be more convenient for error reporting purposes we 134 // drop the error. But really it should never be triggered. Before this point, 135 // our code should have called 'sections()' and reported a proper error on 136 // failure. 137 llvm::consumeError(TableOrErr.takeError()); 138 return "[unknown index]"; 139 } 140 141 template <class ELFT> 142 static std::string describe(const ELFFile<ELFT> &Obj, 143 const typename ELFT::Shdr &Sec) { 144 unsigned SecNdx = &Sec - &cantFail(Obj.sections()).front(); 145 return (object::getELFSectionTypeName(Obj.getHeader().e_machine, 146 Sec.sh_type) + 147 " section with index " + Twine(SecNdx)) 148 .str(); 149 } 150 151 template <class ELFT> 152 std::string getPhdrIndexForError(const ELFFile<ELFT> &Obj, 153 const typename ELFT::Phdr &Phdr) { 154 auto Headers = Obj.program_headers(); 155 if (Headers) 156 return ("[index " + Twine(&Phdr - &Headers->front()) + "]").str(); 157 // See comment in the getSecIndexForError() above. 158 llvm::consumeError(Headers.takeError()); 159 return "[unknown index]"; 160 } 161 162 static inline Error defaultWarningHandler(const Twine &Msg) { 163 return createError(Msg); 164 } 165 166 template <class ELFT> 167 bool checkSectionOffsets(const typename ELFT::Phdr &Phdr, 168 const typename ELFT::Shdr &Sec) { 169 // SHT_NOBITS sections don't need to have an offset inside the segment. 170 if (Sec.sh_type == ELF::SHT_NOBITS) 171 return true; 172 173 if (Sec.sh_offset < Phdr.p_offset) 174 return false; 175 176 // Only non-empty sections can be at the end of a segment. 177 if (Sec.sh_size == 0) 178 return (Sec.sh_offset + 1 <= Phdr.p_offset + Phdr.p_filesz); 179 return Sec.sh_offset + Sec.sh_size <= Phdr.p_offset + Phdr.p_filesz; 180 } 181 182 // Check that an allocatable section belongs to a virtual address 183 // space of a segment. 184 template <class ELFT> 185 bool checkSectionVMA(const typename ELFT::Phdr &Phdr, 186 const typename ELFT::Shdr &Sec) { 187 if (!(Sec.sh_flags & ELF::SHF_ALLOC)) 188 return true; 189 190 if (Sec.sh_addr < Phdr.p_vaddr) 191 return false; 192 193 bool IsTbss = 194 (Sec.sh_type == ELF::SHT_NOBITS) && ((Sec.sh_flags & ELF::SHF_TLS) != 0); 195 // .tbss is special, it only has memory in PT_TLS and has NOBITS properties. 196 bool IsTbssInNonTLS = IsTbss && Phdr.p_type != ELF::PT_TLS; 197 // Only non-empty sections can be at the end of a segment. 198 if (Sec.sh_size == 0 || IsTbssInNonTLS) 199 return Sec.sh_addr + 1 <= Phdr.p_vaddr + Phdr.p_memsz; 200 return Sec.sh_addr + Sec.sh_size <= Phdr.p_vaddr + Phdr.p_memsz; 201 } 202 203 template <class ELFT> 204 bool isSectionInSegment(const typename ELFT::Phdr &Phdr, 205 const typename ELFT::Shdr &Sec) { 206 return checkSectionOffsets<ELFT>(Phdr, Sec) && 207 checkSectionVMA<ELFT>(Phdr, Sec); 208 } 209 210 template <class ELFT> 211 class ELFFile { 212 public: 213 LLVM_ELF_IMPORT_TYPES_ELFT(ELFT) 214 215 // This is a callback that can be passed to a number of functions. 216 // It can be used to ignore non-critical errors (warnings), which is 217 // useful for dumpers, like llvm-readobj. 218 // It accepts a warning message string and returns a success 219 // when the warning should be ignored or an error otherwise. 220 using WarningHandler = llvm::function_ref<Error(const Twine &Msg)>; 221 222 const uint8_t *base() const { return Buf.bytes_begin(); } 223 const uint8_t *end() const { return base() + getBufSize(); } 224 225 size_t getBufSize() const { return Buf.size(); } 226 227 private: 228 StringRef Buf; 229 std::vector<Elf_Shdr> FakeSections; 230 SmallString<0> FakeSectionStrings; 231 232 ELFFile(StringRef Object); 233 234 public: 235 const Elf_Ehdr &getHeader() const { 236 return *reinterpret_cast<const Elf_Ehdr *>(base()); 237 } 238 239 template <typename T> 240 Expected<const T *> getEntry(uint32_t Section, uint32_t Entry) const; 241 template <typename T> 242 Expected<const T *> getEntry(const Elf_Shdr &Section, uint32_t Entry) const; 243 244 Expected<std::vector<VerDef>> 245 getVersionDefinitions(const Elf_Shdr &Sec) const; 246 Expected<std::vector<VerNeed>> getVersionDependencies( 247 const Elf_Shdr &Sec, 248 WarningHandler WarnHandler = &defaultWarningHandler) const; 249 Expected<StringRef> getSymbolVersionByIndex( 250 uint32_t SymbolVersionIndex, bool &IsDefault, 251 SmallVector<std::optional<VersionEntry>, 0> &VersionMap, 252 std::optional<bool> IsSymHidden) const; 253 254 Expected<StringRef> 255 getStringTable(const Elf_Shdr &Section, 256 WarningHandler WarnHandler = &defaultWarningHandler) const; 257 Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section) const; 258 Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section, 259 Elf_Shdr_Range Sections) const; 260 Expected<StringRef> getLinkAsStrtab(const typename ELFT::Shdr &Sec) const; 261 262 Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section) const; 263 Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section, 264 Elf_Shdr_Range Sections) const; 265 266 Expected<uint64_t> getDynSymtabSize() const; 267 268 StringRef getRelocationTypeName(uint32_t Type) const; 269 void getRelocationTypeName(uint32_t Type, 270 SmallVectorImpl<char> &Result) const; 271 uint32_t getRelativeRelocationType() const; 272 273 std::string getDynamicTagAsString(unsigned Arch, uint64_t Type) const; 274 std::string getDynamicTagAsString(uint64_t Type) const; 275 276 /// Get the symbol for a given relocation. 277 Expected<const Elf_Sym *> getRelocationSymbol(const Elf_Rel &Rel, 278 const Elf_Shdr *SymTab) const; 279 280 Expected<SmallVector<std::optional<VersionEntry>, 0>> 281 loadVersionMap(const Elf_Shdr *VerNeedSec, const Elf_Shdr *VerDefSec) const; 282 283 static Expected<ELFFile> create(StringRef Object); 284 285 bool isLE() const { 286 return getHeader().getDataEncoding() == ELF::ELFDATA2LSB; 287 } 288 289 bool isMipsELF64() const { 290 return getHeader().e_machine == ELF::EM_MIPS && 291 getHeader().getFileClass() == ELF::ELFCLASS64; 292 } 293 294 bool isMips64EL() const { return isMipsELF64() && isLE(); } 295 296 Expected<Elf_Shdr_Range> sections() const; 297 298 Expected<Elf_Dyn_Range> dynamicEntries() const; 299 300 Expected<const uint8_t *> 301 toMappedAddr(uint64_t VAddr, 302 WarningHandler WarnHandler = &defaultWarningHandler) const; 303 304 Expected<Elf_Sym_Range> symbols(const Elf_Shdr *Sec) const { 305 if (!Sec) 306 return ArrayRef<Elf_Sym>(nullptr, nullptr); 307 return getSectionContentsAsArray<Elf_Sym>(*Sec); 308 } 309 310 Expected<Elf_Rela_Range> relas(const Elf_Shdr &Sec) const { 311 return getSectionContentsAsArray<Elf_Rela>(Sec); 312 } 313 314 Expected<Elf_Rel_Range> rels(const Elf_Shdr &Sec) const { 315 return getSectionContentsAsArray<Elf_Rel>(Sec); 316 } 317 318 Expected<Elf_Relr_Range> relrs(const Elf_Shdr &Sec) const { 319 return getSectionContentsAsArray<Elf_Relr>(Sec); 320 } 321 322 std::vector<Elf_Rel> decode_relrs(Elf_Relr_Range relrs) const; 323 324 Expected<std::vector<Elf_Rela>> android_relas(const Elf_Shdr &Sec) const; 325 326 /// Iterate over program header table. 327 Expected<Elf_Phdr_Range> program_headers() const { 328 if (getHeader().e_phnum && getHeader().e_phentsize != sizeof(Elf_Phdr)) 329 return createError("invalid e_phentsize: " + 330 Twine(getHeader().e_phentsize)); 331 332 uint64_t HeadersSize = 333 (uint64_t)getHeader().e_phnum * getHeader().e_phentsize; 334 uint64_t PhOff = getHeader().e_phoff; 335 if (PhOff + HeadersSize < PhOff || PhOff + HeadersSize > getBufSize()) 336 return createError("program headers are longer than binary of size " + 337 Twine(getBufSize()) + ": e_phoff = 0x" + 338 Twine::utohexstr(getHeader().e_phoff) + 339 ", e_phnum = " + Twine(getHeader().e_phnum) + 340 ", e_phentsize = " + Twine(getHeader().e_phentsize)); 341 342 auto *Begin = reinterpret_cast<const Elf_Phdr *>(base() + PhOff); 343 return ArrayRef(Begin, Begin + getHeader().e_phnum); 344 } 345 346 /// Get an iterator over notes in a program header. 347 /// 348 /// The program header must be of type \c PT_NOTE. 349 /// 350 /// \param Phdr the program header to iterate over. 351 /// \param Err [out] an error to support fallible iteration, which should 352 /// be checked after iteration ends. 353 Elf_Note_Iterator notes_begin(const Elf_Phdr &Phdr, Error &Err) const { 354 assert(Phdr.p_type == ELF::PT_NOTE && "Phdr is not of type PT_NOTE"); 355 ErrorAsOutParameter ErrAsOutParam(&Err); 356 if (Phdr.p_offset + Phdr.p_filesz > getBufSize()) { 357 Err = 358 createError("invalid offset (0x" + Twine::utohexstr(Phdr.p_offset) + 359 ") or size (0x" + Twine::utohexstr(Phdr.p_filesz) + ")"); 360 return Elf_Note_Iterator(Err); 361 } 362 // Allow 4, 8, and (for Linux core dumps) 0. 363 // TODO: Disallow 1 after all tests are fixed. 364 if (Phdr.p_align != 0 && Phdr.p_align != 1 && Phdr.p_align != 4 && 365 Phdr.p_align != 8) { 366 Err = 367 createError("alignment (" + Twine(Phdr.p_align) + ") is not 4 or 8"); 368 return Elf_Note_Iterator(Err); 369 } 370 return Elf_Note_Iterator(base() + Phdr.p_offset, Phdr.p_filesz, 371 std::max<size_t>(Phdr.p_align, 4), Err); 372 } 373 374 /// Get an iterator over notes in a section. 375 /// 376 /// The section must be of type \c SHT_NOTE. 377 /// 378 /// \param Shdr the section to iterate over. 379 /// \param Err [out] an error to support fallible iteration, which should 380 /// be checked after iteration ends. 381 Elf_Note_Iterator notes_begin(const Elf_Shdr &Shdr, Error &Err) const { 382 assert(Shdr.sh_type == ELF::SHT_NOTE && "Shdr is not of type SHT_NOTE"); 383 ErrorAsOutParameter ErrAsOutParam(&Err); 384 if (Shdr.sh_offset + Shdr.sh_size > getBufSize()) { 385 Err = 386 createError("invalid offset (0x" + Twine::utohexstr(Shdr.sh_offset) + 387 ") or size (0x" + Twine::utohexstr(Shdr.sh_size) + ")"); 388 return Elf_Note_Iterator(Err); 389 } 390 // TODO: Allow just 4 and 8 after all tests are fixed. 391 if (Shdr.sh_addralign != 0 && Shdr.sh_addralign != 1 && 392 Shdr.sh_addralign != 4 && Shdr.sh_addralign != 8) { 393 Err = createError("alignment (" + Twine(Shdr.sh_addralign) + 394 ") is not 4 or 8"); 395 return Elf_Note_Iterator(Err); 396 } 397 return Elf_Note_Iterator(base() + Shdr.sh_offset, Shdr.sh_size, 398 std::max<size_t>(Shdr.sh_addralign, 4), Err); 399 } 400 401 /// Get the end iterator for notes. 402 Elf_Note_Iterator notes_end() const { 403 return Elf_Note_Iterator(); 404 } 405 406 /// Get an iterator range over notes of a program header. 407 /// 408 /// The program header must be of type \c PT_NOTE. 409 /// 410 /// \param Phdr the program header to iterate over. 411 /// \param Err [out] an error to support fallible iteration, which should 412 /// be checked after iteration ends. 413 iterator_range<Elf_Note_Iterator> notes(const Elf_Phdr &Phdr, 414 Error &Err) const { 415 return make_range(notes_begin(Phdr, Err), notes_end()); 416 } 417 418 /// Get an iterator range over notes of a section. 419 /// 420 /// The section must be of type \c SHT_NOTE. 421 /// 422 /// \param Shdr the section to iterate over. 423 /// \param Err [out] an error to support fallible iteration, which should 424 /// be checked after iteration ends. 425 iterator_range<Elf_Note_Iterator> notes(const Elf_Shdr &Shdr, 426 Error &Err) const { 427 return make_range(notes_begin(Shdr, Err), notes_end()); 428 } 429 430 Expected<StringRef> getSectionStringTable( 431 Elf_Shdr_Range Sections, 432 WarningHandler WarnHandler = &defaultWarningHandler) const; 433 Expected<uint32_t> getSectionIndex(const Elf_Sym &Sym, Elf_Sym_Range Syms, 434 DataRegion<Elf_Word> ShndxTable) const; 435 Expected<const Elf_Shdr *> getSection(const Elf_Sym &Sym, 436 const Elf_Shdr *SymTab, 437 DataRegion<Elf_Word> ShndxTable) const; 438 Expected<const Elf_Shdr *> getSection(const Elf_Sym &Sym, 439 Elf_Sym_Range Symtab, 440 DataRegion<Elf_Word> ShndxTable) const; 441 Expected<const Elf_Shdr *> getSection(uint32_t Index) const; 442 443 Expected<const Elf_Sym *> getSymbol(const Elf_Shdr *Sec, 444 uint32_t Index) const; 445 446 Expected<StringRef> 447 getSectionName(const Elf_Shdr &Section, 448 WarningHandler WarnHandler = &defaultWarningHandler) const; 449 Expected<StringRef> getSectionName(const Elf_Shdr &Section, 450 StringRef DotShstrtab) const; 451 template <typename T> 452 Expected<ArrayRef<T>> getSectionContentsAsArray(const Elf_Shdr &Sec) const; 453 Expected<ArrayRef<uint8_t>> getSectionContents(const Elf_Shdr &Sec) const; 454 Expected<ArrayRef<uint8_t>> getSegmentContents(const Elf_Phdr &Phdr) const; 455 456 /// Returns a vector of BBAddrMap structs corresponding to each function 457 /// within the text section that the SHT_LLVM_BB_ADDR_MAP section \p Sec 458 /// is associated with. If the current ELFFile is relocatable, a corresponding 459 /// \p RelaSec must be passed in as an argument. 460 /// Optional out variable to collect all PGO Analyses. New elements are only 461 /// added if no error occurs. If not provided, the PGO Analyses are decoded 462 /// then ignored. 463 Expected<std::vector<BBAddrMap>> 464 decodeBBAddrMap(const Elf_Shdr &Sec, const Elf_Shdr *RelaSec = nullptr, 465 std::vector<PGOAnalysisMap> *PGOAnalyses = nullptr) const; 466 467 /// Returns a map from every section matching \p IsMatch to its relocation 468 /// section, or \p nullptr if it has no relocation section. This function 469 /// returns an error if any of the \p IsMatch calls fail or if it fails to 470 /// retrieve the content section of any relocation section. 471 Expected<MapVector<const Elf_Shdr *, const Elf_Shdr *>> 472 getSectionAndRelocations( 473 std::function<Expected<bool>(const Elf_Shdr &)> IsMatch) const; 474 475 void createFakeSections(); 476 }; 477 478 using ELF32LEFile = ELFFile<ELF32LE>; 479 using ELF64LEFile = ELFFile<ELF64LE>; 480 using ELF32BEFile = ELFFile<ELF32BE>; 481 using ELF64BEFile = ELFFile<ELF64BE>; 482 483 template <class ELFT> 484 inline Expected<const typename ELFT::Shdr *> 485 getSection(typename ELFT::ShdrRange Sections, uint32_t Index) { 486 if (Index >= Sections.size()) 487 return createError("invalid section index: " + Twine(Index)); 488 return &Sections[Index]; 489 } 490 491 template <class ELFT> 492 inline Expected<uint32_t> 493 getExtendedSymbolTableIndex(const typename ELFT::Sym &Sym, unsigned SymIndex, 494 DataRegion<typename ELFT::Word> ShndxTable) { 495 assert(Sym.st_shndx == ELF::SHN_XINDEX); 496 if (!ShndxTable.First) 497 return createError( 498 "found an extended symbol index (" + Twine(SymIndex) + 499 "), but unable to locate the extended symbol index table"); 500 501 Expected<typename ELFT::Word> TableOrErr = ShndxTable[SymIndex]; 502 if (!TableOrErr) 503 return createError("unable to read an extended symbol table at index " + 504 Twine(SymIndex) + ": " + 505 toString(TableOrErr.takeError())); 506 return *TableOrErr; 507 } 508 509 template <class ELFT> 510 Expected<uint32_t> 511 ELFFile<ELFT>::getSectionIndex(const Elf_Sym &Sym, Elf_Sym_Range Syms, 512 DataRegion<Elf_Word> ShndxTable) const { 513 uint32_t Index = Sym.st_shndx; 514 if (Index == ELF::SHN_XINDEX) { 515 Expected<uint32_t> ErrorOrIndex = 516 getExtendedSymbolTableIndex<ELFT>(Sym, &Sym - Syms.begin(), ShndxTable); 517 if (!ErrorOrIndex) 518 return ErrorOrIndex.takeError(); 519 return *ErrorOrIndex; 520 } 521 if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE) 522 return 0; 523 return Index; 524 } 525 526 template <class ELFT> 527 Expected<const typename ELFT::Shdr *> 528 ELFFile<ELFT>::getSection(const Elf_Sym &Sym, const Elf_Shdr *SymTab, 529 DataRegion<Elf_Word> ShndxTable) const { 530 auto SymsOrErr = symbols(SymTab); 531 if (!SymsOrErr) 532 return SymsOrErr.takeError(); 533 return getSection(Sym, *SymsOrErr, ShndxTable); 534 } 535 536 template <class ELFT> 537 Expected<const typename ELFT::Shdr *> 538 ELFFile<ELFT>::getSection(const Elf_Sym &Sym, Elf_Sym_Range Symbols, 539 DataRegion<Elf_Word> ShndxTable) const { 540 auto IndexOrErr = getSectionIndex(Sym, Symbols, ShndxTable); 541 if (!IndexOrErr) 542 return IndexOrErr.takeError(); 543 uint32_t Index = *IndexOrErr; 544 if (Index == 0) 545 return nullptr; 546 return getSection(Index); 547 } 548 549 template <class ELFT> 550 Expected<const typename ELFT::Sym *> 551 ELFFile<ELFT>::getSymbol(const Elf_Shdr *Sec, uint32_t Index) const { 552 auto SymsOrErr = symbols(Sec); 553 if (!SymsOrErr) 554 return SymsOrErr.takeError(); 555 556 Elf_Sym_Range Symbols = *SymsOrErr; 557 if (Index >= Symbols.size()) 558 return createError("unable to get symbol from section " + 559 getSecIndexForError(*this, *Sec) + 560 ": invalid symbol index (" + Twine(Index) + ")"); 561 return &Symbols[Index]; 562 } 563 564 template <class ELFT> 565 template <typename T> 566 Expected<ArrayRef<T>> 567 ELFFile<ELFT>::getSectionContentsAsArray(const Elf_Shdr &Sec) const { 568 if (Sec.sh_entsize != sizeof(T) && sizeof(T) != 1) 569 return createError("section " + getSecIndexForError(*this, Sec) + 570 " has invalid sh_entsize: expected " + Twine(sizeof(T)) + 571 ", but got " + Twine(Sec.sh_entsize)); 572 573 uintX_t Offset = Sec.sh_offset; 574 uintX_t Size = Sec.sh_size; 575 576 if (Size % sizeof(T)) 577 return createError("section " + getSecIndexForError(*this, Sec) + 578 " has an invalid sh_size (" + Twine(Size) + 579 ") which is not a multiple of its sh_entsize (" + 580 Twine(Sec.sh_entsize) + ")"); 581 if (std::numeric_limits<uintX_t>::max() - Offset < Size) 582 return createError("section " + getSecIndexForError(*this, Sec) + 583 " has a sh_offset (0x" + Twine::utohexstr(Offset) + 584 ") + sh_size (0x" + Twine::utohexstr(Size) + 585 ") that cannot be represented"); 586 if (Offset + Size > Buf.size()) 587 return createError("section " + getSecIndexForError(*this, Sec) + 588 " has a sh_offset (0x" + Twine::utohexstr(Offset) + 589 ") + sh_size (0x" + Twine::utohexstr(Size) + 590 ") that is greater than the file size (0x" + 591 Twine::utohexstr(Buf.size()) + ")"); 592 593 if (Offset % alignof(T)) 594 // TODO: this error is untested. 595 return createError("unaligned data"); 596 597 const T *Start = reinterpret_cast<const T *>(base() + Offset); 598 return ArrayRef(Start, Size / sizeof(T)); 599 } 600 601 template <class ELFT> 602 Expected<ArrayRef<uint8_t>> 603 ELFFile<ELFT>::getSegmentContents(const Elf_Phdr &Phdr) const { 604 uintX_t Offset = Phdr.p_offset; 605 uintX_t Size = Phdr.p_filesz; 606 607 if (std::numeric_limits<uintX_t>::max() - Offset < Size) 608 return createError("program header " + getPhdrIndexForError(*this, Phdr) + 609 " has a p_offset (0x" + Twine::utohexstr(Offset) + 610 ") + p_filesz (0x" + Twine::utohexstr(Size) + 611 ") that cannot be represented"); 612 if (Offset + Size > Buf.size()) 613 return createError("program header " + getPhdrIndexForError(*this, Phdr) + 614 " has a p_offset (0x" + Twine::utohexstr(Offset) + 615 ") + p_filesz (0x" + Twine::utohexstr(Size) + 616 ") that is greater than the file size (0x" + 617 Twine::utohexstr(Buf.size()) + ")"); 618 return ArrayRef(base() + Offset, Size); 619 } 620 621 template <class ELFT> 622 Expected<ArrayRef<uint8_t>> 623 ELFFile<ELFT>::getSectionContents(const Elf_Shdr &Sec) const { 624 return getSectionContentsAsArray<uint8_t>(Sec); 625 } 626 627 template <class ELFT> 628 StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const { 629 return getELFRelocationTypeName(getHeader().e_machine, Type); 630 } 631 632 template <class ELFT> 633 void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type, 634 SmallVectorImpl<char> &Result) const { 635 if (!isMipsELF64()) { 636 StringRef Name = getRelocationTypeName(Type); 637 Result.append(Name.begin(), Name.end()); 638 } else { 639 // The Mips N64 ABI allows up to three operations to be specified per 640 // relocation record. Unfortunately there's no easy way to test for the 641 // presence of N64 ELFs as they have no special flag that identifies them 642 // as being N64. We can safely assume at the moment that all Mips 643 // ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough 644 // information to disambiguate between old vs new ABIs. 645 uint8_t Type1 = (Type >> 0) & 0xFF; 646 uint8_t Type2 = (Type >> 8) & 0xFF; 647 uint8_t Type3 = (Type >> 16) & 0xFF; 648 649 // Concat all three relocation type names. 650 StringRef Name = getRelocationTypeName(Type1); 651 Result.append(Name.begin(), Name.end()); 652 653 Name = getRelocationTypeName(Type2); 654 Result.append(1, '/'); 655 Result.append(Name.begin(), Name.end()); 656 657 Name = getRelocationTypeName(Type3); 658 Result.append(1, '/'); 659 Result.append(Name.begin(), Name.end()); 660 } 661 } 662 663 template <class ELFT> 664 uint32_t ELFFile<ELFT>::getRelativeRelocationType() const { 665 return getELFRelativeRelocationType(getHeader().e_machine); 666 } 667 668 template <class ELFT> 669 Expected<SmallVector<std::optional<VersionEntry>, 0>> 670 ELFFile<ELFT>::loadVersionMap(const Elf_Shdr *VerNeedSec, 671 const Elf_Shdr *VerDefSec) const { 672 SmallVector<std::optional<VersionEntry>, 0> VersionMap; 673 674 // The first two version indexes are reserved. 675 // Index 0 is VER_NDX_LOCAL, index 1 is VER_NDX_GLOBAL. 676 VersionMap.push_back(VersionEntry()); 677 VersionMap.push_back(VersionEntry()); 678 679 auto InsertEntry = [&](unsigned N, StringRef Version, bool IsVerdef) { 680 if (N >= VersionMap.size()) 681 VersionMap.resize(N + 1); 682 VersionMap[N] = {std::string(Version), IsVerdef}; 683 }; 684 685 if (VerDefSec) { 686 Expected<std::vector<VerDef>> Defs = getVersionDefinitions(*VerDefSec); 687 if (!Defs) 688 return Defs.takeError(); 689 for (const VerDef &Def : *Defs) 690 InsertEntry(Def.Ndx & ELF::VERSYM_VERSION, Def.Name, true); 691 } 692 693 if (VerNeedSec) { 694 Expected<std::vector<VerNeed>> Deps = getVersionDependencies(*VerNeedSec); 695 if (!Deps) 696 return Deps.takeError(); 697 for (const VerNeed &Dep : *Deps) 698 for (const VernAux &Aux : Dep.AuxV) 699 InsertEntry(Aux.Other & ELF::VERSYM_VERSION, Aux.Name, false); 700 } 701 702 return VersionMap; 703 } 704 705 template <class ELFT> 706 Expected<const typename ELFT::Sym *> 707 ELFFile<ELFT>::getRelocationSymbol(const Elf_Rel &Rel, 708 const Elf_Shdr *SymTab) const { 709 uint32_t Index = Rel.getSymbol(isMips64EL()); 710 if (Index == 0) 711 return nullptr; 712 return getEntry<Elf_Sym>(*SymTab, Index); 713 } 714 715 template <class ELFT> 716 Expected<StringRef> 717 ELFFile<ELFT>::getSectionStringTable(Elf_Shdr_Range Sections, 718 WarningHandler WarnHandler) const { 719 uint32_t Index = getHeader().e_shstrndx; 720 if (Index == ELF::SHN_XINDEX) { 721 // If the section name string table section index is greater than 722 // or equal to SHN_LORESERVE, then the actual index of the section name 723 // string table section is contained in the sh_link field of the section 724 // header at index 0. 725 if (Sections.empty()) 726 return createError( 727 "e_shstrndx == SHN_XINDEX, but the section header table is empty"); 728 729 Index = Sections[0].sh_link; 730 } 731 732 // There is no section name string table. Return FakeSectionStrings which 733 // is non-empty if we have created fake sections. 734 if (!Index) 735 return FakeSectionStrings; 736 737 if (Index >= Sections.size()) 738 return createError("section header string table index " + Twine(Index) + 739 " does not exist"); 740 return getStringTable(Sections[Index], WarnHandler); 741 } 742 743 /// This function finds the number of dynamic symbols using a GNU hash table. 744 /// 745 /// @param Table The GNU hash table for .dynsym. 746 template <class ELFT> 747 static Expected<uint64_t> 748 getDynSymtabSizeFromGnuHash(const typename ELFT::GnuHash &Table, 749 const void *BufEnd) { 750 using Elf_Word = typename ELFT::Word; 751 if (Table.nbuckets == 0) 752 return Table.symndx + 1; 753 uint64_t LastSymIdx = 0; 754 // Find the index of the first symbol in the last chain. 755 for (Elf_Word Val : Table.buckets()) 756 LastSymIdx = std::max(LastSymIdx, (uint64_t)Val); 757 const Elf_Word *It = 758 reinterpret_cast<const Elf_Word *>(Table.values(LastSymIdx).end()); 759 // Locate the end of the chain to find the last symbol index. 760 while (It < BufEnd && (*It & 1) == 0) { 761 ++LastSymIdx; 762 ++It; 763 } 764 if (It >= BufEnd) { 765 return createStringError( 766 object_error::parse_failed, 767 "no terminator found for GNU hash section before buffer end"); 768 } 769 return LastSymIdx + 1; 770 } 771 772 /// This function determines the number of dynamic symbols. It reads section 773 /// headers first. If section headers are not available, the number of 774 /// symbols will be inferred by parsing dynamic hash tables. 775 template <class ELFT> 776 Expected<uint64_t> ELFFile<ELFT>::getDynSymtabSize() const { 777 // Read .dynsym section header first if available. 778 Expected<Elf_Shdr_Range> SectionsOrError = sections(); 779 if (!SectionsOrError) 780 return SectionsOrError.takeError(); 781 for (const Elf_Shdr &Sec : *SectionsOrError) { 782 if (Sec.sh_type == ELF::SHT_DYNSYM) { 783 if (Sec.sh_size % Sec.sh_entsize != 0) { 784 return createStringError(object_error::parse_failed, 785 "SHT_DYNSYM section has sh_size (" + 786 Twine(Sec.sh_size) + ") % sh_entsize (" + 787 Twine(Sec.sh_entsize) + ") that is not 0"); 788 } 789 return Sec.sh_size / Sec.sh_entsize; 790 } 791 } 792 793 if (!SectionsOrError->empty()) { 794 // Section headers are available but .dynsym header is not found. 795 // Return 0 as .dynsym does not exist. 796 return 0; 797 } 798 799 // Section headers do not exist. Falling back to infer 800 // upper bound of .dynsym from .gnu.hash and .hash. 801 Expected<Elf_Dyn_Range> DynTable = dynamicEntries(); 802 if (!DynTable) 803 return DynTable.takeError(); 804 std::optional<uint64_t> ElfHash; 805 std::optional<uint64_t> ElfGnuHash; 806 for (const Elf_Dyn &Entry : *DynTable) { 807 switch (Entry.d_tag) { 808 case ELF::DT_HASH: 809 ElfHash = Entry.d_un.d_ptr; 810 break; 811 case ELF::DT_GNU_HASH: 812 ElfGnuHash = Entry.d_un.d_ptr; 813 break; 814 } 815 } 816 if (ElfGnuHash) { 817 Expected<const uint8_t *> TablePtr = toMappedAddr(*ElfGnuHash); 818 if (!TablePtr) 819 return TablePtr.takeError(); 820 const Elf_GnuHash *Table = 821 reinterpret_cast<const Elf_GnuHash *>(TablePtr.get()); 822 return getDynSymtabSizeFromGnuHash<ELFT>(*Table, this->Buf.bytes_end()); 823 } 824 825 // Search SYSV hash table to try to find the upper bound of dynsym. 826 if (ElfHash) { 827 Expected<const uint8_t *> TablePtr = toMappedAddr(*ElfHash); 828 if (!TablePtr) 829 return TablePtr.takeError(); 830 const Elf_Hash *Table = reinterpret_cast<const Elf_Hash *>(TablePtr.get()); 831 return Table->nchain; 832 } 833 return 0; 834 } 835 836 template <class ELFT> ELFFile<ELFT>::ELFFile(StringRef Object) : Buf(Object) {} 837 838 template <class ELFT> 839 Expected<ELFFile<ELFT>> ELFFile<ELFT>::create(StringRef Object) { 840 if (sizeof(Elf_Ehdr) > Object.size()) 841 return createError("invalid buffer: the size (" + Twine(Object.size()) + 842 ") is smaller than an ELF header (" + 843 Twine(sizeof(Elf_Ehdr)) + ")"); 844 return ELFFile(Object); 845 } 846 847 /// Used by llvm-objdump -d (which needs sections for disassembly) to 848 /// disassemble objects without a section header table (e.g. ET_CORE objects 849 /// analyzed by linux perf or ET_EXEC with llvm-strip --strip-sections). 850 template <class ELFT> void ELFFile<ELFT>::createFakeSections() { 851 if (!FakeSections.empty()) 852 return; 853 auto PhdrsOrErr = program_headers(); 854 if (!PhdrsOrErr) 855 return; 856 857 FakeSectionStrings += '\0'; 858 for (auto [Idx, Phdr] : llvm::enumerate(*PhdrsOrErr)) { 859 if (Phdr.p_type != ELF::PT_LOAD || !(Phdr.p_flags & ELF::PF_X)) 860 continue; 861 Elf_Shdr FakeShdr = {}; 862 FakeShdr.sh_type = ELF::SHT_PROGBITS; 863 FakeShdr.sh_flags = ELF::SHF_ALLOC | ELF::SHF_EXECINSTR; 864 FakeShdr.sh_addr = Phdr.p_vaddr; 865 FakeShdr.sh_size = Phdr.p_memsz; 866 FakeShdr.sh_offset = Phdr.p_offset; 867 // Create a section name based on the p_type and index. 868 FakeShdr.sh_name = FakeSectionStrings.size(); 869 FakeSectionStrings += ("PT_LOAD#" + Twine(Idx)).str(); 870 FakeSectionStrings += '\0'; 871 FakeSections.push_back(FakeShdr); 872 } 873 } 874 875 template <class ELFT> 876 Expected<typename ELFT::ShdrRange> ELFFile<ELFT>::sections() const { 877 const uintX_t SectionTableOffset = getHeader().e_shoff; 878 if (SectionTableOffset == 0) { 879 if (!FakeSections.empty()) 880 return ArrayRef(FakeSections.data(), FakeSections.size()); 881 return ArrayRef<Elf_Shdr>(); 882 } 883 884 if (getHeader().e_shentsize != sizeof(Elf_Shdr)) 885 return createError("invalid e_shentsize in ELF header: " + 886 Twine(getHeader().e_shentsize)); 887 888 const uint64_t FileSize = Buf.size(); 889 if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize || 890 SectionTableOffset + (uintX_t)sizeof(Elf_Shdr) < SectionTableOffset) 891 return createError( 892 "section header table goes past the end of the file: e_shoff = 0x" + 893 Twine::utohexstr(SectionTableOffset)); 894 895 // Invalid address alignment of section headers 896 if (SectionTableOffset & (alignof(Elf_Shdr) - 1)) 897 // TODO: this error is untested. 898 return createError("invalid alignment of section headers"); 899 900 const Elf_Shdr *First = 901 reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset); 902 903 uintX_t NumSections = getHeader().e_shnum; 904 if (NumSections == 0) 905 NumSections = First->sh_size; 906 907 if (NumSections > UINT64_MAX / sizeof(Elf_Shdr)) 908 return createError("invalid number of sections specified in the NULL " 909 "section's sh_size field (" + 910 Twine(NumSections) + ")"); 911 912 const uint64_t SectionTableSize = NumSections * sizeof(Elf_Shdr); 913 if (SectionTableOffset + SectionTableSize < SectionTableOffset) 914 return createError( 915 "invalid section header table offset (e_shoff = 0x" + 916 Twine::utohexstr(SectionTableOffset) + 917 ") or invalid number of sections specified in the first section " 918 "header's sh_size field (0x" + 919 Twine::utohexstr(NumSections) + ")"); 920 921 // Section table goes past end of file! 922 if (SectionTableOffset + SectionTableSize > FileSize) 923 return createError("section table goes past the end of file"); 924 return ArrayRef(First, NumSections); 925 } 926 927 template <class ELFT> 928 template <typename T> 929 Expected<const T *> ELFFile<ELFT>::getEntry(uint32_t Section, 930 uint32_t Entry) const { 931 auto SecOrErr = getSection(Section); 932 if (!SecOrErr) 933 return SecOrErr.takeError(); 934 return getEntry<T>(**SecOrErr, Entry); 935 } 936 937 template <class ELFT> 938 template <typename T> 939 Expected<const T *> ELFFile<ELFT>::getEntry(const Elf_Shdr &Section, 940 uint32_t Entry) const { 941 Expected<ArrayRef<T>> EntriesOrErr = getSectionContentsAsArray<T>(Section); 942 if (!EntriesOrErr) 943 return EntriesOrErr.takeError(); 944 945 ArrayRef<T> Arr = *EntriesOrErr; 946 if (Entry >= Arr.size()) 947 return createError( 948 "can't read an entry at 0x" + 949 Twine::utohexstr(Entry * static_cast<uint64_t>(sizeof(T))) + 950 ": it goes past the end of the section (0x" + 951 Twine::utohexstr(Section.sh_size) + ")"); 952 return &Arr[Entry]; 953 } 954 955 template <typename ELFT> 956 Expected<StringRef> ELFFile<ELFT>::getSymbolVersionByIndex( 957 uint32_t SymbolVersionIndex, bool &IsDefault, 958 SmallVector<std::optional<VersionEntry>, 0> &VersionMap, 959 std::optional<bool> IsSymHidden) const { 960 size_t VersionIndex = SymbolVersionIndex & llvm::ELF::VERSYM_VERSION; 961 962 // Special markers for unversioned symbols. 963 if (VersionIndex == llvm::ELF::VER_NDX_LOCAL || 964 VersionIndex == llvm::ELF::VER_NDX_GLOBAL) { 965 IsDefault = false; 966 return ""; 967 } 968 969 // Lookup this symbol in the version table. 970 if (VersionIndex >= VersionMap.size() || !VersionMap[VersionIndex]) 971 return createError("SHT_GNU_versym section refers to a version index " + 972 Twine(VersionIndex) + " which is missing"); 973 974 const VersionEntry &Entry = *VersionMap[VersionIndex]; 975 // A default version (@@) is only available for defined symbols. 976 if (!Entry.IsVerDef || IsSymHidden.value_or(false)) 977 IsDefault = false; 978 else 979 IsDefault = !(SymbolVersionIndex & llvm::ELF::VERSYM_HIDDEN); 980 return Entry.Name.c_str(); 981 } 982 983 template <class ELFT> 984 Expected<std::vector<VerDef>> 985 ELFFile<ELFT>::getVersionDefinitions(const Elf_Shdr &Sec) const { 986 Expected<StringRef> StrTabOrErr = getLinkAsStrtab(Sec); 987 if (!StrTabOrErr) 988 return StrTabOrErr.takeError(); 989 990 Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec); 991 if (!ContentsOrErr) 992 return createError("cannot read content of " + describe(*this, Sec) + ": " + 993 toString(ContentsOrErr.takeError())); 994 995 const uint8_t *Start = ContentsOrErr->data(); 996 const uint8_t *End = Start + ContentsOrErr->size(); 997 998 auto ExtractNextAux = [&](const uint8_t *&VerdauxBuf, 999 unsigned VerDefNdx) -> Expected<VerdAux> { 1000 if (VerdauxBuf + sizeof(Elf_Verdaux) > End) 1001 return createError("invalid " + describe(*this, Sec) + 1002 ": version definition " + Twine(VerDefNdx) + 1003 " refers to an auxiliary entry that goes past the end " 1004 "of the section"); 1005 1006 auto *Verdaux = reinterpret_cast<const Elf_Verdaux *>(VerdauxBuf); 1007 VerdauxBuf += Verdaux->vda_next; 1008 1009 VerdAux Aux; 1010 Aux.Offset = VerdauxBuf - Start; 1011 if (Verdaux->vda_name <= StrTabOrErr->size()) 1012 Aux.Name = std::string(StrTabOrErr->drop_front(Verdaux->vda_name)); 1013 else 1014 Aux.Name = ("<invalid vda_name: " + Twine(Verdaux->vda_name) + ">").str(); 1015 return Aux; 1016 }; 1017 1018 std::vector<VerDef> Ret; 1019 const uint8_t *VerdefBuf = Start; 1020 for (unsigned I = 1; I <= /*VerDefsNum=*/Sec.sh_info; ++I) { 1021 if (VerdefBuf + sizeof(Elf_Verdef) > End) 1022 return createError("invalid " + describe(*this, Sec) + 1023 ": version definition " + Twine(I) + 1024 " goes past the end of the section"); 1025 1026 if (reinterpret_cast<uintptr_t>(VerdefBuf) % sizeof(uint32_t) != 0) 1027 return createError( 1028 "invalid " + describe(*this, Sec) + 1029 ": found a misaligned version definition entry at offset 0x" + 1030 Twine::utohexstr(VerdefBuf - Start)); 1031 1032 unsigned Version = *reinterpret_cast<const Elf_Half *>(VerdefBuf); 1033 if (Version != 1) 1034 return createError("unable to dump " + describe(*this, Sec) + 1035 ": version " + Twine(Version) + 1036 " is not yet supported"); 1037 1038 const Elf_Verdef *D = reinterpret_cast<const Elf_Verdef *>(VerdefBuf); 1039 VerDef &VD = *Ret.emplace(Ret.end()); 1040 VD.Offset = VerdefBuf - Start; 1041 VD.Version = D->vd_version; 1042 VD.Flags = D->vd_flags; 1043 VD.Ndx = D->vd_ndx; 1044 VD.Cnt = D->vd_cnt; 1045 VD.Hash = D->vd_hash; 1046 1047 const uint8_t *VerdauxBuf = VerdefBuf + D->vd_aux; 1048 for (unsigned J = 0; J < D->vd_cnt; ++J) { 1049 if (reinterpret_cast<uintptr_t>(VerdauxBuf) % sizeof(uint32_t) != 0) 1050 return createError("invalid " + describe(*this, Sec) + 1051 ": found a misaligned auxiliary entry at offset 0x" + 1052 Twine::utohexstr(VerdauxBuf - Start)); 1053 1054 Expected<VerdAux> AuxOrErr = ExtractNextAux(VerdauxBuf, I); 1055 if (!AuxOrErr) 1056 return AuxOrErr.takeError(); 1057 1058 if (J == 0) 1059 VD.Name = AuxOrErr->Name; 1060 else 1061 VD.AuxV.push_back(*AuxOrErr); 1062 } 1063 1064 VerdefBuf += D->vd_next; 1065 } 1066 1067 return Ret; 1068 } 1069 1070 template <class ELFT> 1071 Expected<std::vector<VerNeed>> 1072 ELFFile<ELFT>::getVersionDependencies(const Elf_Shdr &Sec, 1073 WarningHandler WarnHandler) const { 1074 StringRef StrTab; 1075 Expected<StringRef> StrTabOrErr = getLinkAsStrtab(Sec); 1076 if (!StrTabOrErr) { 1077 if (Error E = WarnHandler(toString(StrTabOrErr.takeError()))) 1078 return std::move(E); 1079 } else { 1080 StrTab = *StrTabOrErr; 1081 } 1082 1083 Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec); 1084 if (!ContentsOrErr) 1085 return createError("cannot read content of " + describe(*this, Sec) + ": " + 1086 toString(ContentsOrErr.takeError())); 1087 1088 const uint8_t *Start = ContentsOrErr->data(); 1089 const uint8_t *End = Start + ContentsOrErr->size(); 1090 const uint8_t *VerneedBuf = Start; 1091 1092 std::vector<VerNeed> Ret; 1093 for (unsigned I = 1; I <= /*VerneedNum=*/Sec.sh_info; ++I) { 1094 if (VerneedBuf + sizeof(Elf_Verdef) > End) 1095 return createError("invalid " + describe(*this, Sec) + 1096 ": version dependency " + Twine(I) + 1097 " goes past the end of the section"); 1098 1099 if (reinterpret_cast<uintptr_t>(VerneedBuf) % sizeof(uint32_t) != 0) 1100 return createError( 1101 "invalid " + describe(*this, Sec) + 1102 ": found a misaligned version dependency entry at offset 0x" + 1103 Twine::utohexstr(VerneedBuf - Start)); 1104 1105 unsigned Version = *reinterpret_cast<const Elf_Half *>(VerneedBuf); 1106 if (Version != 1) 1107 return createError("unable to dump " + describe(*this, Sec) + 1108 ": version " + Twine(Version) + 1109 " is not yet supported"); 1110 1111 const Elf_Verneed *Verneed = 1112 reinterpret_cast<const Elf_Verneed *>(VerneedBuf); 1113 1114 VerNeed &VN = *Ret.emplace(Ret.end()); 1115 VN.Version = Verneed->vn_version; 1116 VN.Cnt = Verneed->vn_cnt; 1117 VN.Offset = VerneedBuf - Start; 1118 1119 if (Verneed->vn_file < StrTab.size()) 1120 VN.File = std::string(StrTab.data() + Verneed->vn_file); 1121 else 1122 VN.File = ("<corrupt vn_file: " + Twine(Verneed->vn_file) + ">").str(); 1123 1124 const uint8_t *VernauxBuf = VerneedBuf + Verneed->vn_aux; 1125 for (unsigned J = 0; J < Verneed->vn_cnt; ++J) { 1126 if (reinterpret_cast<uintptr_t>(VernauxBuf) % sizeof(uint32_t) != 0) 1127 return createError("invalid " + describe(*this, Sec) + 1128 ": found a misaligned auxiliary entry at offset 0x" + 1129 Twine::utohexstr(VernauxBuf - Start)); 1130 1131 if (VernauxBuf + sizeof(Elf_Vernaux) > End) 1132 return createError( 1133 "invalid " + describe(*this, Sec) + ": version dependency " + 1134 Twine(I) + 1135 " refers to an auxiliary entry that goes past the end " 1136 "of the section"); 1137 1138 const Elf_Vernaux *Vernaux = 1139 reinterpret_cast<const Elf_Vernaux *>(VernauxBuf); 1140 1141 VernAux &Aux = *VN.AuxV.emplace(VN.AuxV.end()); 1142 Aux.Hash = Vernaux->vna_hash; 1143 Aux.Flags = Vernaux->vna_flags; 1144 Aux.Other = Vernaux->vna_other; 1145 Aux.Offset = VernauxBuf - Start; 1146 if (StrTab.size() <= Vernaux->vna_name) 1147 Aux.Name = "<corrupt>"; 1148 else 1149 Aux.Name = std::string(StrTab.drop_front(Vernaux->vna_name)); 1150 1151 VernauxBuf += Vernaux->vna_next; 1152 } 1153 VerneedBuf += Verneed->vn_next; 1154 } 1155 return Ret; 1156 } 1157 1158 template <class ELFT> 1159 Expected<const typename ELFT::Shdr *> 1160 ELFFile<ELFT>::getSection(uint32_t Index) const { 1161 auto TableOrErr = sections(); 1162 if (!TableOrErr) 1163 return TableOrErr.takeError(); 1164 return object::getSection<ELFT>(*TableOrErr, Index); 1165 } 1166 1167 template <class ELFT> 1168 Expected<StringRef> 1169 ELFFile<ELFT>::getStringTable(const Elf_Shdr &Section, 1170 WarningHandler WarnHandler) const { 1171 if (Section.sh_type != ELF::SHT_STRTAB) 1172 if (Error E = WarnHandler("invalid sh_type for string table section " + 1173 getSecIndexForError(*this, Section) + 1174 ": expected SHT_STRTAB, but got " + 1175 object::getELFSectionTypeName( 1176 getHeader().e_machine, Section.sh_type))) 1177 return std::move(E); 1178 1179 auto V = getSectionContentsAsArray<char>(Section); 1180 if (!V) 1181 return V.takeError(); 1182 ArrayRef<char> Data = *V; 1183 if (Data.empty()) 1184 return createError("SHT_STRTAB string table section " + 1185 getSecIndexForError(*this, Section) + " is empty"); 1186 if (Data.back() != '\0') 1187 return createError("SHT_STRTAB string table section " + 1188 getSecIndexForError(*this, Section) + 1189 " is non-null terminated"); 1190 return StringRef(Data.begin(), Data.size()); 1191 } 1192 1193 template <class ELFT> 1194 Expected<ArrayRef<typename ELFT::Word>> 1195 ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section) const { 1196 auto SectionsOrErr = sections(); 1197 if (!SectionsOrErr) 1198 return SectionsOrErr.takeError(); 1199 return getSHNDXTable(Section, *SectionsOrErr); 1200 } 1201 1202 template <class ELFT> 1203 Expected<ArrayRef<typename ELFT::Word>> 1204 ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section, 1205 Elf_Shdr_Range Sections) const { 1206 assert(Section.sh_type == ELF::SHT_SYMTAB_SHNDX); 1207 auto VOrErr = getSectionContentsAsArray<Elf_Word>(Section); 1208 if (!VOrErr) 1209 return VOrErr.takeError(); 1210 ArrayRef<Elf_Word> V = *VOrErr; 1211 auto SymTableOrErr = object::getSection<ELFT>(Sections, Section.sh_link); 1212 if (!SymTableOrErr) 1213 return SymTableOrErr.takeError(); 1214 const Elf_Shdr &SymTable = **SymTableOrErr; 1215 if (SymTable.sh_type != ELF::SHT_SYMTAB && 1216 SymTable.sh_type != ELF::SHT_DYNSYM) 1217 return createError( 1218 "SHT_SYMTAB_SHNDX section is linked with " + 1219 object::getELFSectionTypeName(getHeader().e_machine, SymTable.sh_type) + 1220 " section (expected SHT_SYMTAB/SHT_DYNSYM)"); 1221 1222 uint64_t Syms = SymTable.sh_size / sizeof(Elf_Sym); 1223 if (V.size() != Syms) 1224 return createError("SHT_SYMTAB_SHNDX has " + Twine(V.size()) + 1225 " entries, but the symbol table associated has " + 1226 Twine(Syms)); 1227 1228 return V; 1229 } 1230 1231 template <class ELFT> 1232 Expected<StringRef> 1233 ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const { 1234 auto SectionsOrErr = sections(); 1235 if (!SectionsOrErr) 1236 return SectionsOrErr.takeError(); 1237 return getStringTableForSymtab(Sec, *SectionsOrErr); 1238 } 1239 1240 template <class ELFT> 1241 Expected<StringRef> 1242 ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec, 1243 Elf_Shdr_Range Sections) const { 1244 1245 if (Sec.sh_type != ELF::SHT_SYMTAB && Sec.sh_type != ELF::SHT_DYNSYM) 1246 return createError( 1247 "invalid sh_type for symbol table, expected SHT_SYMTAB or SHT_DYNSYM"); 1248 Expected<const Elf_Shdr *> SectionOrErr = 1249 object::getSection<ELFT>(Sections, Sec.sh_link); 1250 if (!SectionOrErr) 1251 return SectionOrErr.takeError(); 1252 return getStringTable(**SectionOrErr); 1253 } 1254 1255 template <class ELFT> 1256 Expected<StringRef> 1257 ELFFile<ELFT>::getLinkAsStrtab(const typename ELFT::Shdr &Sec) const { 1258 Expected<const typename ELFT::Shdr *> StrTabSecOrErr = 1259 getSection(Sec.sh_link); 1260 if (!StrTabSecOrErr) 1261 return createError("invalid section linked to " + describe(*this, Sec) + 1262 ": " + toString(StrTabSecOrErr.takeError())); 1263 1264 Expected<StringRef> StrTabOrErr = getStringTable(**StrTabSecOrErr); 1265 if (!StrTabOrErr) 1266 return createError("invalid string table linked to " + 1267 describe(*this, Sec) + ": " + 1268 toString(StrTabOrErr.takeError())); 1269 return *StrTabOrErr; 1270 } 1271 1272 template <class ELFT> 1273 Expected<StringRef> 1274 ELFFile<ELFT>::getSectionName(const Elf_Shdr &Section, 1275 WarningHandler WarnHandler) const { 1276 auto SectionsOrErr = sections(); 1277 if (!SectionsOrErr) 1278 return SectionsOrErr.takeError(); 1279 auto Table = getSectionStringTable(*SectionsOrErr, WarnHandler); 1280 if (!Table) 1281 return Table.takeError(); 1282 return getSectionName(Section, *Table); 1283 } 1284 1285 template <class ELFT> 1286 Expected<StringRef> ELFFile<ELFT>::getSectionName(const Elf_Shdr &Section, 1287 StringRef DotShstrtab) const { 1288 uint32_t Offset = Section.sh_name; 1289 if (Offset == 0) 1290 return StringRef(); 1291 if (Offset >= DotShstrtab.size()) 1292 return createError("a section " + getSecIndexForError(*this, Section) + 1293 " has an invalid sh_name (0x" + 1294 Twine::utohexstr(Offset) + 1295 ") offset which goes past the end of the " 1296 "section name string table"); 1297 return StringRef(DotShstrtab.data() + Offset); 1298 } 1299 1300 /// This function returns the hash value for a symbol in the .dynsym section 1301 /// Name of the API remains consistent as specified in the libelf 1302 /// REF : http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#hash 1303 inline uint32_t hashSysV(StringRef SymbolName) { 1304 uint32_t H = 0; 1305 for (uint8_t C : SymbolName) { 1306 H = (H << 4) + C; 1307 H ^= (H >> 24) & 0xf0; 1308 } 1309 return H & 0x0fffffff; 1310 } 1311 1312 /// This function returns the hash value for a symbol in the .dynsym section 1313 /// for the GNU hash table. The implementation is defined in the GNU hash ABI. 1314 /// REF : https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=bfd/elf.c#l222 1315 inline uint32_t hashGnu(StringRef Name) { 1316 uint32_t H = 5381; 1317 for (uint8_t C : Name) 1318 H = (H << 5) + H + C; 1319 return H; 1320 } 1321 1322 } // end namespace object 1323 } // end namespace llvm 1324 1325 #endif // LLVM_OBJECT_ELF_H 1326