1 //===- ELF.h - ELF object file implementation -------------------*- 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 // This file declares the ELFFile template class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_OBJECT_ELF_H
15 #define LLVM_OBJECT_ELF_H
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/Object/ELFTypes.h"
19 #include "llvm/Support/MemoryBuffer.h"
24 StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type);
26 // Subclasses of ELFFile may need this for template instantiation
27 inline std::pair<unsigned char, unsigned char>
28 getElfArchType(StringRef Object) {
29 if (Object.size() < ELF::EI_NIDENT)
30 return std::make_pair((uint8_t)ELF::ELFCLASSNONE,
31 (uint8_t)ELF::ELFDATANONE);
32 return std::make_pair((uint8_t)Object[ELF::EI_CLASS],
33 (uint8_t)Object[ELF::EI_DATA]);
39 LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
40 typedef typename std::conditional<ELFT::Is64Bits,
41 uint64_t, uint32_t>::type uintX_t;
43 typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
44 typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
45 typedef Elf_Sym_Impl<ELFT> Elf_Sym;
46 typedef Elf_Dyn_Impl<ELFT> Elf_Dyn;
47 typedef Elf_Phdr_Impl<ELFT> Elf_Phdr;
48 typedef Elf_Rel_Impl<ELFT, false> Elf_Rel;
49 typedef Elf_Rel_Impl<ELFT, true> Elf_Rela;
50 typedef Elf_Verdef_Impl<ELFT> Elf_Verdef;
51 typedef Elf_Verdaux_Impl<ELFT> Elf_Verdaux;
52 typedef Elf_Verneed_Impl<ELFT> Elf_Verneed;
53 typedef Elf_Vernaux_Impl<ELFT> Elf_Vernaux;
54 typedef Elf_Versym_Impl<ELFT> Elf_Versym;
55 typedef Elf_Hash_Impl<ELFT> Elf_Hash;
56 typedef iterator_range<const Elf_Dyn *> Elf_Dyn_Range;
57 typedef iterator_range<const Elf_Shdr *> Elf_Shdr_Range;
58 typedef iterator_range<const Elf_Sym *> Elf_Sym_Range;
60 const uint8_t *base() const {
61 return reinterpret_cast<const uint8_t *>(Buf.data());
68 const Elf_Ehdr *Header;
69 const Elf_Shdr *SectionHeaderTable = nullptr;
70 StringRef DotShstrtab; // Section header string table.
74 const T *getEntry(uint32_t Section, uint32_t Entry) const;
76 const T *getEntry(const Elf_Shdr *Section, uint32_t Entry) const;
78 ErrorOr<StringRef> getStringTable(const Elf_Shdr *Section) const;
79 ErrorOr<StringRef> getStringTableForSymtab(const Elf_Shdr &Section) const;
81 ErrorOr<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section) const;
83 void VerifyStrTab(const Elf_Shdr *sh) const;
85 StringRef getRelocationTypeName(uint32_t Type) const;
86 void getRelocationTypeName(uint32_t Type,
87 SmallVectorImpl<char> &Result) const;
89 /// \brief Get the symbol for a given relocation.
90 const Elf_Sym *getRelocationSymbol(const Elf_Rel *Rel,
91 const Elf_Shdr *SymTab) const;
93 ELFFile(StringRef Object, std::error_code &EC);
95 bool isMipsELF64() const {
96 return Header->e_machine == ELF::EM_MIPS &&
97 Header->getFileClass() == ELF::ELFCLASS64;
100 bool isMips64EL() const {
101 return Header->e_machine == ELF::EM_MIPS &&
102 Header->getFileClass() == ELF::ELFCLASS64 &&
103 Header->getDataEncoding() == ELF::ELFDATA2LSB;
106 ErrorOr<const Elf_Dyn *> dynamic_table_begin(const Elf_Phdr *Phdr) const;
107 ErrorOr<const Elf_Dyn *> dynamic_table_end(const Elf_Phdr *Phdr) const;
108 ErrorOr<Elf_Dyn_Range> dynamic_table(const Elf_Phdr *Phdr) const {
109 ErrorOr<const Elf_Dyn *> Begin = dynamic_table_begin(Phdr);
110 if (std::error_code EC = Begin.getError())
112 ErrorOr<const Elf_Dyn *> End = dynamic_table_end(Phdr);
113 if (std::error_code EC = End.getError())
115 return make_range(*Begin, *End);
118 const Elf_Shdr *section_begin() const;
119 const Elf_Shdr *section_end() const;
120 Elf_Shdr_Range sections() const {
121 return make_range(section_begin(), section_end());
124 const Elf_Sym *symbol_begin(const Elf_Shdr *Sec) const {
127 if (Sec->sh_entsize != sizeof(Elf_Sym))
128 report_fatal_error("Invalid symbol size");
129 return reinterpret_cast<const Elf_Sym *>(base() + Sec->sh_offset);
131 const Elf_Sym *symbol_end(const Elf_Shdr *Sec) const {
134 uint64_t Size = Sec->sh_size;
135 if (Size % sizeof(Elf_Sym))
136 report_fatal_error("Invalid symbol table size");
137 return symbol_begin(Sec) + Size / sizeof(Elf_Sym);
139 Elf_Sym_Range symbols(const Elf_Shdr *Sec) const {
140 return make_range(symbol_begin(Sec), symbol_end(Sec));
143 typedef iterator_range<const Elf_Rela *> Elf_Rela_Range;
145 const Elf_Rela *rela_begin(const Elf_Shdr *sec) const {
146 if (sec->sh_entsize != sizeof(Elf_Rela))
147 report_fatal_error("Invalid relocation entry size");
148 return reinterpret_cast<const Elf_Rela *>(base() + sec->sh_offset);
151 const Elf_Rela *rela_end(const Elf_Shdr *sec) const {
152 uint64_t Size = sec->sh_size;
153 if (Size % sizeof(Elf_Rela))
154 report_fatal_error("Invalid relocation table size");
155 return rela_begin(sec) + Size / sizeof(Elf_Rela);
158 Elf_Rela_Range relas(const Elf_Shdr *Sec) const {
159 return make_range(rela_begin(Sec), rela_end(Sec));
162 const Elf_Rel *rel_begin(const Elf_Shdr *sec) const {
163 if (sec->sh_entsize != sizeof(Elf_Rel))
164 report_fatal_error("Invalid relocation entry size");
165 return reinterpret_cast<const Elf_Rel *>(base() + sec->sh_offset);
168 const Elf_Rel *rel_end(const Elf_Shdr *sec) const {
169 uint64_t Size = sec->sh_size;
170 if (Size % sizeof(Elf_Rel))
171 report_fatal_error("Invalid relocation table size");
172 return rel_begin(sec) + Size / sizeof(Elf_Rel);
175 typedef iterator_range<const Elf_Rel *> Elf_Rel_Range;
176 Elf_Rel_Range rels(const Elf_Shdr *Sec) const {
177 return make_range(rel_begin(Sec), rel_end(Sec));
180 /// \brief Iterate over program header table.
181 const Elf_Phdr *program_header_begin() const {
182 if (Header->e_phnum && Header->e_phentsize != sizeof(Elf_Phdr))
183 report_fatal_error("Invalid program header size");
184 return reinterpret_cast<const Elf_Phdr *>(base() + Header->e_phoff);
187 const Elf_Phdr *program_header_end() const {
188 return program_header_begin() + Header->e_phnum;
191 typedef iterator_range<const Elf_Phdr *> Elf_Phdr_Range;
193 const Elf_Phdr_Range program_headers() const {
194 return make_range(program_header_begin(), program_header_end());
197 uint64_t getNumSections() const;
198 uintX_t getStringTableIndex() const;
199 uint32_t getExtendedSymbolTableIndex(const Elf_Sym *Sym,
200 const Elf_Shdr *SymTab,
201 ArrayRef<Elf_Word> ShndxTable) const;
202 const Elf_Ehdr *getHeader() const { return Header; }
203 ErrorOr<const Elf_Shdr *> getSection(const Elf_Sym *Sym,
204 const Elf_Shdr *SymTab,
205 ArrayRef<Elf_Word> ShndxTable) const;
206 ErrorOr<const Elf_Shdr *> getSection(uint32_t Index) const;
208 const Elf_Sym *getSymbol(const Elf_Shdr *Sec, uint32_t Index) const {
209 return &*(symbol_begin(Sec) + Index);
212 ErrorOr<StringRef> getSectionName(const Elf_Shdr *Section) const;
213 template <typename T>
214 ErrorOr<ArrayRef<T>> getSectionContentsAsArray(const Elf_Shdr *Sec) const;
215 ErrorOr<ArrayRef<uint8_t> > getSectionContents(const Elf_Shdr *Sec) const;
218 typedef ELFFile<ELFType<support::little, false>> ELF32LEFile;
219 typedef ELFFile<ELFType<support::little, true>> ELF64LEFile;
220 typedef ELFFile<ELFType<support::big, false>> ELF32BEFile;
221 typedef ELFFile<ELFType<support::big, true>> ELF64BEFile;
223 template <class ELFT>
224 uint32_t ELFFile<ELFT>::getExtendedSymbolTableIndex(
225 const Elf_Sym *Sym, const Elf_Shdr *SymTab,
226 ArrayRef<Elf_Word> ShndxTable) const {
227 assert(Sym->st_shndx == ELF::SHN_XINDEX);
228 unsigned Index = Sym - symbol_begin(SymTab);
230 // The size of the table was checked in getSHNDXTable.
231 return ShndxTable[Index];
234 template <class ELFT>
235 ErrorOr<const typename ELFFile<ELFT>::Elf_Shdr *>
236 ELFFile<ELFT>::getSection(const Elf_Sym *Sym, const Elf_Shdr *SymTab,
237 ArrayRef<Elf_Word> ShndxTable) const {
238 uint32_t Index = Sym->st_shndx;
239 if (Index == ELF::SHN_XINDEX)
240 return getSection(getExtendedSymbolTableIndex(Sym, SymTab, ShndxTable));
242 if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE)
244 return getSection(Sym->st_shndx);
247 template <class ELFT>
248 template <typename T>
250 ELFFile<ELFT>::getSectionContentsAsArray(const Elf_Shdr *Sec) const {
251 uintX_t Offset = Sec->sh_offset;
252 uintX_t Size = Sec->sh_size;
254 if (Size % sizeof(T))
255 return object_error::parse_failed;
256 if (Offset + Size > Buf.size())
257 return object_error::parse_failed;
259 const T *Start = reinterpret_cast<const T *>(base() + Offset);
260 return makeArrayRef(Start, Size / sizeof(T));
263 template <class ELFT>
264 ErrorOr<ArrayRef<uint8_t>>
265 ELFFile<ELFT>::getSectionContents(const Elf_Shdr *Sec) const {
266 return getSectionContentsAsArray<uint8_t>(Sec);
269 template <class ELFT>
270 StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
271 return getELFRelocationTypeName(Header->e_machine, Type);
274 template <class ELFT>
275 void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type,
276 SmallVectorImpl<char> &Result) const {
277 if (!isMipsELF64()) {
278 StringRef Name = getRelocationTypeName(Type);
279 Result.append(Name.begin(), Name.end());
281 // The Mips N64 ABI allows up to three operations to be specified per
282 // relocation record. Unfortunately there's no easy way to test for the
283 // presence of N64 ELFs as they have no special flag that identifies them
284 // as being N64. We can safely assume at the moment that all Mips
285 // ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough
286 // information to disambiguate between old vs new ABIs.
287 uint8_t Type1 = (Type >> 0) & 0xFF;
288 uint8_t Type2 = (Type >> 8) & 0xFF;
289 uint8_t Type3 = (Type >> 16) & 0xFF;
291 // Concat all three relocation type names.
292 StringRef Name = getRelocationTypeName(Type1);
293 Result.append(Name.begin(), Name.end());
295 Name = getRelocationTypeName(Type2);
296 Result.append(1, '/');
297 Result.append(Name.begin(), Name.end());
299 Name = getRelocationTypeName(Type3);
300 Result.append(1, '/');
301 Result.append(Name.begin(), Name.end());
305 template <class ELFT>
306 const typename ELFFile<ELFT>::Elf_Sym *
307 ELFFile<ELFT>::getRelocationSymbol(const Elf_Rel *Rel,
308 const Elf_Shdr *SymTab) const {
309 uint32_t Index = Rel->getSymbol(isMips64EL());
312 return getEntry<Elf_Sym>(SymTab, Index);
315 template <class ELFT>
316 uint64_t ELFFile<ELFT>::getNumSections() const {
317 assert(Header && "Header not initialized!");
318 if (Header->e_shnum == ELF::SHN_UNDEF && Header->e_shoff > 0) {
319 assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
320 return SectionHeaderTable->sh_size;
322 return Header->e_shnum;
325 template <class ELFT>
326 typename ELFFile<ELFT>::uintX_t ELFFile<ELFT>::getStringTableIndex() const {
327 if (Header->e_shnum == ELF::SHN_UNDEF) {
328 if (Header->e_shstrndx == ELF::SHN_HIRESERVE)
329 return SectionHeaderTable->sh_link;
330 if (Header->e_shstrndx >= getNumSections())
333 return Header->e_shstrndx;
336 template <class ELFT>
337 ELFFile<ELFT>::ELFFile(StringRef Object, std::error_code &EC)
339 const uint64_t FileSize = Buf.size();
341 if (sizeof(Elf_Ehdr) > FileSize) {
343 EC = object_error::parse_failed;
347 Header = reinterpret_cast<const Elf_Ehdr *>(base());
349 if (Header->e_shoff == 0)
352 const uint64_t SectionTableOffset = Header->e_shoff;
354 if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize) {
355 // Section header table goes past end of file!
356 EC = object_error::parse_failed;
360 // The getNumSections() call below depends on SectionHeaderTable being set.
362 reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
363 const uint64_t SectionTableSize = getNumSections() * Header->e_shentsize;
365 if (SectionTableOffset + SectionTableSize > FileSize) {
366 // Section table goes past end of file!
367 EC = object_error::parse_failed;
371 // Get string table sections.
372 uintX_t StringTableIndex = getStringTableIndex();
373 if (StringTableIndex) {
374 ErrorOr<const Elf_Shdr *> StrTabSecOrErr = getSection(StringTableIndex);
375 if ((EC = StrTabSecOrErr.getError()))
378 ErrorOr<StringRef> StringTableOrErr = getStringTable(*StrTabSecOrErr);
379 if ((EC = StringTableOrErr.getError()))
381 DotShstrtab = *StringTableOrErr;
384 EC = std::error_code();
387 template <class ELFT>
388 static bool compareAddr(uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *Phdr) {
389 return VAddr < Phdr->p_vaddr;
392 template <class ELFT>
393 const typename ELFFile<ELFT>::Elf_Shdr *ELFFile<ELFT>::section_begin() const {
394 if (Header->e_shentsize != sizeof(Elf_Shdr))
396 "Invalid section header entry size (e_shentsize) in ELF header");
397 return reinterpret_cast<const Elf_Shdr *>(base() + Header->e_shoff);
400 template <class ELFT>
401 const typename ELFFile<ELFT>::Elf_Shdr *ELFFile<ELFT>::section_end() const {
402 return section_begin() + getNumSections();
405 template <class ELFT>
406 ErrorOr<const typename ELFFile<ELFT>::Elf_Dyn *>
407 ELFFile<ELFT>::dynamic_table_begin(const Elf_Phdr *Phdr) const {
410 assert(Phdr->p_type == ELF::PT_DYNAMIC && "Got the wrong program header");
411 uintX_t Offset = Phdr->p_offset;
412 if (Offset > Buf.size())
413 return object_error::parse_failed;
414 return reinterpret_cast<const Elf_Dyn *>(base() + Offset);
417 template <class ELFT>
418 ErrorOr<const typename ELFFile<ELFT>::Elf_Dyn *>
419 ELFFile<ELFT>::dynamic_table_end(const Elf_Phdr *Phdr) const {
422 assert(Phdr->p_type == ELF::PT_DYNAMIC && "Got the wrong program header");
423 uintX_t Size = Phdr->p_filesz;
424 if (Size % sizeof(Elf_Dyn))
425 return object_error::elf_invalid_dynamic_table_size;
426 // FIKME: Check for overflow?
427 uintX_t End = Phdr->p_offset + Size;
428 if (End > Buf.size())
429 return object_error::parse_failed;
430 return reinterpret_cast<const Elf_Dyn *>(base() + End);
433 template <class ELFT>
434 template <typename T>
435 const T *ELFFile<ELFT>::getEntry(uint32_t Section, uint32_t Entry) const {
436 ErrorOr<const Elf_Shdr *> Sec = getSection(Section);
437 if (std::error_code EC = Sec.getError())
438 report_fatal_error(EC.message());
439 return getEntry<T>(*Sec, Entry);
442 template <class ELFT>
443 template <typename T>
444 const T *ELFFile<ELFT>::getEntry(const Elf_Shdr *Section,
445 uint32_t Entry) const {
446 return reinterpret_cast<const T *>(base() + Section->sh_offset +
447 (Entry * Section->sh_entsize));
450 template <class ELFT>
451 ErrorOr<const typename ELFFile<ELFT>::Elf_Shdr *>
452 ELFFile<ELFT>::getSection(uint32_t Index) const {
453 assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
454 if (Index >= getNumSections())
455 return object_error::invalid_section_index;
457 return reinterpret_cast<const Elf_Shdr *>(
458 reinterpret_cast<const char *>(SectionHeaderTable) +
459 (Index * Header->e_shentsize));
462 template <class ELFT>
464 ELFFile<ELFT>::getStringTable(const Elf_Shdr *Section) const {
465 if (Section->sh_type != ELF::SHT_STRTAB)
466 return object_error::parse_failed;
467 uint64_t Offset = Section->sh_offset;
468 uint64_t Size = Section->sh_size;
469 if (Offset + Size > Buf.size())
470 return object_error::parse_failed;
471 StringRef Data((const char *)base() + Section->sh_offset, Size);
472 if (Data[Size - 1] != '\0')
473 return object_error::string_table_non_null_end;
477 template <class ELFT>
478 ErrorOr<ArrayRef<typename ELFFile<ELFT>::Elf_Word>>
479 ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section) const {
480 assert(Section.sh_type == ELF::SHT_SYMTAB_SHNDX);
481 const Elf_Word *ShndxTableBegin =
482 reinterpret_cast<const Elf_Word *>(base() + Section.sh_offset);
483 uintX_t Size = Section.sh_size;
484 if (Size % sizeof(uint32_t))
485 return object_error::parse_failed;
486 uintX_t NumSymbols = Size / sizeof(uint32_t);
487 const Elf_Word *ShndxTableEnd = ShndxTableBegin + NumSymbols;
488 if (reinterpret_cast<const char *>(ShndxTableEnd) > Buf.end())
489 return object_error::parse_failed;
490 ErrorOr<const Elf_Shdr *> SymTableOrErr = getSection(Section.sh_link);
491 if (std::error_code EC = SymTableOrErr.getError())
493 const Elf_Shdr &SymTable = **SymTableOrErr;
494 if (SymTable.sh_type != ELF::SHT_SYMTAB &&
495 SymTable.sh_type != ELF::SHT_DYNSYM)
496 return object_error::parse_failed;
497 if (NumSymbols != (SymTable.sh_size / sizeof(Elf_Sym)))
498 return object_error::parse_failed;
499 return makeArrayRef(ShndxTableBegin, ShndxTableEnd);
502 template <class ELFT>
504 ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const {
505 if (Sec.sh_type != ELF::SHT_SYMTAB && Sec.sh_type != ELF::SHT_DYNSYM)
506 return object_error::parse_failed;
507 ErrorOr<const Elf_Shdr *> SectionOrErr = getSection(Sec.sh_link);
508 if (std::error_code EC = SectionOrErr.getError())
510 return getStringTable(*SectionOrErr);
513 template <class ELFT>
515 ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section) const {
516 uint32_t Offset = Section->sh_name;
519 if (Offset >= DotShstrtab.size())
520 return object_error::parse_failed;
521 return StringRef(DotShstrtab.data() + Offset);
524 /// This function returns the hash value for a symbol in the .dynsym section
525 /// Name of the API remains consistent as specified in the libelf
526 /// REF : http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#hash
527 static inline unsigned elf_hash(StringRef &symbolName) {
529 for (unsigned i = 0, j = symbolName.size(); i < j; i++) {
530 h = (h << 4) + symbolName[i];
538 } // end namespace object
539 } // end namespace llvm