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.
71 StringRef DotStrtab; // Symbol header string table.
72 const Elf_Shdr *dot_symtab_sec = nullptr; // Symbol table section.
74 const Elf_Shdr *SymbolTableSectionHeaderIndex = nullptr;
78 const T *getEntry(uint32_t Section, uint32_t Entry) const;
80 const T *getEntry(const Elf_Shdr *Section, uint32_t Entry) const;
82 const Elf_Shdr *getDotSymtabSec() const { return dot_symtab_sec; }
84 ErrorOr<StringRef> getStringTable(const Elf_Shdr *Section) const;
85 ErrorOr<StringRef> getStringTableForSymtab(const Elf_Shdr &Section) const;
87 void VerifyStrTab(const Elf_Shdr *sh) const;
89 StringRef getRelocationTypeName(uint32_t Type) const;
90 void getRelocationTypeName(uint32_t Type,
91 SmallVectorImpl<char> &Result) const;
93 /// \brief Get the symbol table section and symbol for a given relocation.
95 std::pair<const Elf_Shdr *, const Elf_Sym *>
96 getRelocationSymbol(const Elf_Shdr *RelSec, const RelT *Rel) const;
98 ELFFile(StringRef Object, std::error_code &EC);
100 bool isMipsELF64() const {
101 return Header->e_machine == ELF::EM_MIPS &&
102 Header->getFileClass() == ELF::ELFCLASS64;
105 bool isMips64EL() const {
106 return Header->e_machine == ELF::EM_MIPS &&
107 Header->getFileClass() == ELF::ELFCLASS64 &&
108 Header->getDataEncoding() == ELF::ELFDATA2LSB;
111 ErrorOr<const Elf_Dyn *> dynamic_table_begin(const Elf_Phdr *Phdr) const;
112 ErrorOr<const Elf_Dyn *> dynamic_table_end(const Elf_Phdr *Phdr) const;
113 ErrorOr<Elf_Dyn_Range> dynamic_table(const Elf_Phdr *Phdr) const {
114 ErrorOr<const Elf_Dyn *> Begin = dynamic_table_begin(Phdr);
115 if (std::error_code EC = Begin.getError())
117 ErrorOr<const Elf_Dyn *> End = dynamic_table_end(Phdr);
118 if (std::error_code EC = End.getError())
120 return make_range(*Begin, *End);
123 const Elf_Shdr *section_begin() const;
124 const Elf_Shdr *section_end() const;
125 Elf_Shdr_Range sections() const {
126 return make_range(section_begin(), section_end());
129 const Elf_Sym *symbol_begin(const Elf_Shdr *Sec) const {
132 if (Sec->sh_entsize != sizeof(Elf_Sym))
133 report_fatal_error("Invalid symbol size");
134 return reinterpret_cast<const Elf_Sym *>(base() + Sec->sh_offset);
136 const Elf_Sym *symbol_end(const Elf_Shdr *Sec) const {
139 uint64_t Size = Sec->sh_size;
140 if (Size % sizeof(Elf_Sym))
141 report_fatal_error("Invalid symbol table size");
142 return symbol_begin(Sec) + Size / sizeof(Elf_Sym);
144 Elf_Sym_Range symbols(const Elf_Shdr *Sec) const {
145 return make_range(symbol_begin(Sec), symbol_end(Sec));
148 typedef iterator_range<const Elf_Rela *> Elf_Rela_Range;
150 const Elf_Rela *rela_begin(const Elf_Shdr *sec) const {
151 if (sec->sh_entsize != sizeof(Elf_Rela))
152 report_fatal_error("Invalid relocation entry size");
153 return reinterpret_cast<const Elf_Rela *>(base() + sec->sh_offset);
156 const Elf_Rela *rela_end(const Elf_Shdr *sec) const {
157 uint64_t Size = sec->sh_size;
158 if (Size % sizeof(Elf_Rela))
159 report_fatal_error("Invalid relocation table size");
160 return rela_begin(sec) + Size / sizeof(Elf_Rela);
163 Elf_Rela_Range relas(const Elf_Shdr *Sec) const {
164 return make_range(rela_begin(Sec), rela_end(Sec));
167 const Elf_Rel *rel_begin(const Elf_Shdr *sec) const {
168 if (sec->sh_entsize != sizeof(Elf_Rel))
169 report_fatal_error("Invalid relocation entry size");
170 return reinterpret_cast<const Elf_Rel *>(base() + sec->sh_offset);
173 const Elf_Rel *rel_end(const Elf_Shdr *sec) const {
174 uint64_t Size = sec->sh_size;
175 if (Size % sizeof(Elf_Rel))
176 report_fatal_error("Invalid relocation table size");
177 return rel_begin(sec) + Size / sizeof(Elf_Rel);
180 typedef iterator_range<const Elf_Rel *> Elf_Rel_Range;
181 Elf_Rel_Range rels(const Elf_Shdr *Sec) const {
182 return make_range(rel_begin(Sec), rel_end(Sec));
185 /// \brief Iterate over program header table.
186 const Elf_Phdr *program_header_begin() const {
187 if (Header->e_phnum && Header->e_phentsize != sizeof(Elf_Phdr))
188 report_fatal_error("Invalid program header size");
189 return reinterpret_cast<const Elf_Phdr *>(base() + Header->e_phoff);
192 const Elf_Phdr *program_header_end() const {
193 return program_header_begin() + Header->e_phnum;
196 typedef iterator_range<const Elf_Phdr *> Elf_Phdr_Range;
198 const Elf_Phdr_Range program_headers() const {
199 return make_range(program_header_begin(), program_header_end());
202 uint64_t getNumSections() const;
203 uintX_t getStringTableIndex() const;
204 ELF::Elf64_Word getExtendedSymbolTableIndex(const Elf_Sym *symb) const;
205 const Elf_Ehdr *getHeader() const { return Header; }
206 ErrorOr<const Elf_Shdr *> getSection(const Elf_Sym *symb) const;
207 ErrorOr<const Elf_Shdr *> getSection(uint32_t Index) const;
209 const Elf_Sym *getSymbol(const Elf_Shdr *Sec, uint32_t Index) const {
210 return &*(symbol_begin(Sec) + Index);
213 ErrorOr<StringRef> getSectionName(const Elf_Shdr *Section) const;
214 ErrorOr<ArrayRef<uint8_t> > getSectionContents(const Elf_Shdr *Sec) const;
217 typedef ELFFile<ELFType<support::little, false>> ELF32LEFile;
218 typedef ELFFile<ELFType<support::little, true>> ELF64LEFile;
219 typedef ELFFile<ELFType<support::big, false>> ELF32BEFile;
220 typedef ELFFile<ELFType<support::big, true>> ELF64BEFile;
222 template <class ELFT>
224 ELFFile<ELFT>::getExtendedSymbolTableIndex(const Elf_Sym *Sym) const {
225 assert(Sym->st_shndx == ELF::SHN_XINDEX);
226 unsigned Index = Sym - symbol_begin(dot_symtab_sec);
228 // FIXME: error checking
229 const Elf_Word *ShndxTable = reinterpret_cast<const Elf_Word *>(
230 base() + SymbolTableSectionHeaderIndex->sh_offset);
231 return ShndxTable[Index];
234 template <class ELFT>
235 ErrorOr<const typename ELFFile<ELFT>::Elf_Shdr *>
236 ELFFile<ELFT>::getSection(const Elf_Sym *symb) const {
237 uint32_t Index = symb->st_shndx;
238 if (Index == ELF::SHN_XINDEX)
239 return getSection(getExtendedSymbolTableIndex(symb));
240 if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE)
242 return getSection(symb->st_shndx);
245 template <class ELFT>
246 ErrorOr<ArrayRef<uint8_t> >
247 ELFFile<ELFT>::getSectionContents(const Elf_Shdr *Sec) const {
248 if (Sec->sh_offset + Sec->sh_size > Buf.size())
249 return object_error::parse_failed;
250 const uint8_t *Start = base() + Sec->sh_offset;
251 return makeArrayRef(Start, Sec->sh_size);
254 template <class ELFT>
255 StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
256 return getELFRelocationTypeName(Header->e_machine, Type);
259 template <class ELFT>
260 void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type,
261 SmallVectorImpl<char> &Result) const {
262 if (!isMipsELF64()) {
263 StringRef Name = getRelocationTypeName(Type);
264 Result.append(Name.begin(), Name.end());
266 // The Mips N64 ABI allows up to three operations to be specified per
267 // relocation record. Unfortunately there's no easy way to test for the
268 // presence of N64 ELFs as they have no special flag that identifies them
269 // as being N64. We can safely assume at the moment that all Mips
270 // ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough
271 // information to disambiguate between old vs new ABIs.
272 uint8_t Type1 = (Type >> 0) & 0xFF;
273 uint8_t Type2 = (Type >> 8) & 0xFF;
274 uint8_t Type3 = (Type >> 16) & 0xFF;
276 // Concat all three relocation type names.
277 StringRef Name = getRelocationTypeName(Type1);
278 Result.append(Name.begin(), Name.end());
280 Name = getRelocationTypeName(Type2);
281 Result.append(1, '/');
282 Result.append(Name.begin(), Name.end());
284 Name = getRelocationTypeName(Type3);
285 Result.append(1, '/');
286 Result.append(Name.begin(), Name.end());
290 template <class ELFT>
291 template <class RelT>
292 std::pair<const typename ELFFile<ELFT>::Elf_Shdr *,
293 const typename ELFFile<ELFT>::Elf_Sym *>
294 ELFFile<ELFT>::getRelocationSymbol(const Elf_Shdr *Sec, const RelT *Rel) const {
296 return std::make_pair(nullptr, nullptr);
297 ErrorOr<const Elf_Shdr *> SymTableOrErr = getSection(Sec->sh_link);
298 if (std::error_code EC = SymTableOrErr.getError())
299 report_fatal_error(EC.message());
300 const Elf_Shdr *SymTable = *SymTableOrErr;
301 return std::make_pair(
302 SymTable, getEntry<Elf_Sym>(SymTable, Rel->getSymbol(isMips64EL())));
305 template <class ELFT>
306 uint64_t ELFFile<ELFT>::getNumSections() const {
307 assert(Header && "Header not initialized!");
308 if (Header->e_shnum == ELF::SHN_UNDEF && Header->e_shoff > 0) {
309 assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
310 return SectionHeaderTable->sh_size;
312 return Header->e_shnum;
315 template <class ELFT>
316 typename ELFFile<ELFT>::uintX_t ELFFile<ELFT>::getStringTableIndex() const {
317 if (Header->e_shnum == ELF::SHN_UNDEF) {
318 if (Header->e_shstrndx == ELF::SHN_HIRESERVE)
319 return SectionHeaderTable->sh_link;
320 if (Header->e_shstrndx >= getNumSections())
323 return Header->e_shstrndx;
326 template <class ELFT>
327 ELFFile<ELFT>::ELFFile(StringRef Object, std::error_code &EC)
329 const uint64_t FileSize = Buf.size();
331 if (sizeof(Elf_Ehdr) > FileSize) {
333 EC = object_error::parse_failed;
337 Header = reinterpret_cast<const Elf_Ehdr *>(base());
339 if (Header->e_shoff == 0)
342 const uint64_t SectionTableOffset = Header->e_shoff;
344 if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize) {
345 // Section header table goes past end of file!
346 EC = object_error::parse_failed;
350 // The getNumSections() call below depends on SectionHeaderTable being set.
352 reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
353 const uint64_t SectionTableSize = getNumSections() * Header->e_shentsize;
355 if (SectionTableOffset + SectionTableSize > FileSize) {
356 // Section table goes past end of file!
357 EC = object_error::parse_failed;
361 // Scan sections for special sections.
363 for (const Elf_Shdr &Sec : sections()) {
364 switch (Sec.sh_type) {
365 case ELF::SHT_SYMTAB_SHNDX:
366 if (SymbolTableSectionHeaderIndex) {
367 // More than one .symtab_shndx!
368 EC = object_error::parse_failed;
371 SymbolTableSectionHeaderIndex = &Sec;
373 case ELF::SHT_SYMTAB: {
374 if (dot_symtab_sec) {
375 // More than one .symtab!
376 EC = object_error::parse_failed;
379 dot_symtab_sec = &Sec;
380 ErrorOr<StringRef> SymtabOrErr = getStringTableForSymtab(Sec);
381 if ((EC = SymtabOrErr.getError()))
383 DotStrtab = *SymtabOrErr;
388 // Get string table sections.
389 uintX_t StringTableIndex = getStringTableIndex();
390 if (StringTableIndex) {
391 ErrorOr<const Elf_Shdr *> StrTabSecOrErr = getSection(StringTableIndex);
392 if ((EC = StrTabSecOrErr.getError()))
395 ErrorOr<StringRef> SymtabOrErr = getStringTable(*StrTabSecOrErr);
396 if ((EC = SymtabOrErr.getError()))
398 DotShstrtab = *SymtabOrErr;
401 EC = std::error_code();
404 template <class ELFT>
405 static bool compareAddr(uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *Phdr) {
406 return VAddr < Phdr->p_vaddr;
409 template <class ELFT>
410 const typename ELFFile<ELFT>::Elf_Shdr *ELFFile<ELFT>::section_begin() const {
411 if (Header->e_shentsize != sizeof(Elf_Shdr))
413 "Invalid section header entry size (e_shentsize) in ELF header");
414 return reinterpret_cast<const Elf_Shdr *>(base() + Header->e_shoff);
417 template <class ELFT>
418 const typename ELFFile<ELFT>::Elf_Shdr *ELFFile<ELFT>::section_end() const {
419 return section_begin() + getNumSections();
422 template <class ELFT>
423 ErrorOr<const typename ELFFile<ELFT>::Elf_Dyn *>
424 ELFFile<ELFT>::dynamic_table_begin(const Elf_Phdr *Phdr) const {
427 assert(Phdr->p_type == ELF::PT_DYNAMIC && "Got the wrong program header");
428 uintX_t Offset = Phdr->p_offset;
429 if (Offset > Buf.size())
430 return object_error::parse_failed;
431 return reinterpret_cast<const Elf_Dyn *>(base() + Offset);
434 template <class ELFT>
435 ErrorOr<const typename ELFFile<ELFT>::Elf_Dyn *>
436 ELFFile<ELFT>::dynamic_table_end(const Elf_Phdr *Phdr) const {
439 assert(Phdr->p_type == ELF::PT_DYNAMIC && "Got the wrong program header");
440 uintX_t Size = Phdr->p_filesz;
441 if (Size % sizeof(Elf_Dyn))
442 return object_error::elf_invalid_dynamic_table_size;
443 // FIKME: Check for overflow?
444 uintX_t End = Phdr->p_offset + Size;
445 if (End > Buf.size())
446 return object_error::parse_failed;
447 return reinterpret_cast<const Elf_Dyn *>(base() + End);
450 template <class ELFT>
451 template <typename T>
452 const T *ELFFile<ELFT>::getEntry(uint32_t Section, uint32_t Entry) const {
453 ErrorOr<const Elf_Shdr *> Sec = getSection(Section);
454 if (std::error_code EC = Sec.getError())
455 report_fatal_error(EC.message());
456 return getEntry<T>(*Sec, Entry);
459 template <class ELFT>
460 template <typename T>
461 const T *ELFFile<ELFT>::getEntry(const Elf_Shdr *Section,
462 uint32_t Entry) const {
463 return reinterpret_cast<const T *>(base() + Section->sh_offset +
464 (Entry * Section->sh_entsize));
467 template <class ELFT>
468 ErrorOr<const typename ELFFile<ELFT>::Elf_Shdr *>
469 ELFFile<ELFT>::getSection(uint32_t Index) const {
470 assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
471 if (Index >= getNumSections())
472 return object_error::invalid_section_index;
474 return reinterpret_cast<const Elf_Shdr *>(
475 reinterpret_cast<const char *>(SectionHeaderTable) +
476 (Index * Header->e_shentsize));
479 template <class ELFT>
481 ELFFile<ELFT>::getStringTable(const Elf_Shdr *Section) const {
482 if (Section->sh_type != ELF::SHT_STRTAB)
483 return object_error::parse_failed;
484 uint64_t Offset = Section->sh_offset;
485 uint64_t Size = Section->sh_size;
486 if (Offset + Size > Buf.size())
487 return object_error::parse_failed;
488 StringRef Data((const char *)base() + Section->sh_offset, Size);
489 if (Data[Size - 1] != '\0')
490 return object_error::string_table_non_null_end;
494 template <class ELFT>
496 ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const {
497 if (Sec.sh_type != ELF::SHT_SYMTAB && Sec.sh_type != ELF::SHT_DYNSYM)
498 return object_error::parse_failed;
499 ErrorOr<const Elf_Shdr *> SectionOrErr = getSection(Sec.sh_link);
500 if (std::error_code EC = SectionOrErr.getError())
502 return getStringTable(*SectionOrErr);
505 template <class ELFT>
507 ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section) const {
508 uint32_t Offset = Section->sh_name;
511 if (Offset >= DotShstrtab.size())
512 return object_error::parse_failed;
513 return StringRef(DotShstrtab.data() + Offset);
516 /// This function returns the hash value for a symbol in the .dynsym section
517 /// Name of the API remains consistent as specified in the libelf
518 /// REF : http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#hash
519 static inline unsigned elf_hash(StringRef &symbolName) {
521 for (unsigned i = 0, j = symbolName.size(); i < j; i++) {
522 h = (h << 4) + symbolName[i];
530 } // end namespace object
531 } // end namespace llvm