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/ArrayRef.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/Object/ELFTypes.h"
21 #include "llvm/Object/Error.h"
22 #include "llvm/Support/ELF.h"
23 #include "llvm/Support/Endian.h"
24 #include "llvm/Support/Error.h"
34 StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type);
35 StringRef getELFSectionTypeName(uint32_t Machine, uint32_t Type);
37 // Subclasses of ELFFile may need this for template instantiation
38 inline std::pair<unsigned char, unsigned char>
39 getElfArchType(StringRef Object) {
40 if (Object.size() < ELF::EI_NIDENT)
41 return std::make_pair((uint8_t)ELF::ELFCLASSNONE,
42 (uint8_t)ELF::ELFDATANONE);
43 return std::make_pair((uint8_t)Object[ELF::EI_CLASS],
44 (uint8_t)Object[ELF::EI_DATA]);
47 static inline Error createError(StringRef Err) {
48 return make_error<StringError>(Err, object_error::parse_failed);
54 LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
55 using uintX_t = typename ELFT::uint;
56 using Elf_Ehdr = typename ELFT::Ehdr;
57 using Elf_Shdr = typename ELFT::Shdr;
58 using Elf_Sym = typename ELFT::Sym;
59 using Elf_Dyn = typename ELFT::Dyn;
60 using Elf_Phdr = typename ELFT::Phdr;
61 using Elf_Rel = typename ELFT::Rel;
62 using Elf_Rela = typename ELFT::Rela;
63 using Elf_Verdef = typename ELFT::Verdef;
64 using Elf_Verdaux = typename ELFT::Verdaux;
65 using Elf_Verneed = typename ELFT::Verneed;
66 using Elf_Vernaux = typename ELFT::Vernaux;
67 using Elf_Versym = typename ELFT::Versym;
68 using Elf_Hash = typename ELFT::Hash;
69 using Elf_GnuHash = typename ELFT::GnuHash;
70 using Elf_Dyn_Range = typename ELFT::DynRange;
71 using Elf_Shdr_Range = typename ELFT::ShdrRange;
72 using Elf_Sym_Range = typename ELFT::SymRange;
73 using Elf_Rel_Range = typename ELFT::RelRange;
74 using Elf_Rela_Range = typename ELFT::RelaRange;
75 using Elf_Phdr_Range = typename ELFT::PhdrRange;
77 const uint8_t *base() const {
78 return reinterpret_cast<const uint8_t *>(Buf.data());
81 size_t getBufSize() const { return Buf.size(); }
87 const Elf_Ehdr *getHeader() const {
88 return reinterpret_cast<const Elf_Ehdr *>(base());
92 Expected<const T *> getEntry(uint32_t Section, uint32_t Entry) const;
94 Expected<const T *> getEntry(const Elf_Shdr *Section, uint32_t Entry) const;
96 Expected<StringRef> getStringTable(const Elf_Shdr *Section) const;
97 Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section) const;
98 Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section,
99 Elf_Shdr_Range Sections) const;
101 Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section) const;
102 Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section,
103 Elf_Shdr_Range Sections) const;
105 void VerifyStrTab(const Elf_Shdr *sh) const;
107 StringRef getRelocationTypeName(uint32_t Type) const;
108 void getRelocationTypeName(uint32_t Type,
109 SmallVectorImpl<char> &Result) const;
111 /// \brief Get the symbol for a given relocation.
112 Expected<const Elf_Sym *> getRelocationSymbol(const Elf_Rel *Rel,
113 const Elf_Shdr *SymTab) const;
115 ELFFile(StringRef Object);
117 bool isMipsELF64() const {
118 return getHeader()->e_machine == ELF::EM_MIPS &&
119 getHeader()->getFileClass() == ELF::ELFCLASS64;
122 bool isMips64EL() const {
123 return isMipsELF64() &&
124 getHeader()->getDataEncoding() == ELF::ELFDATA2LSB;
127 Expected<Elf_Shdr_Range> sections() const;
129 Expected<Elf_Sym_Range> symbols(const Elf_Shdr *Sec) const {
131 return makeArrayRef<Elf_Sym>(nullptr, nullptr);
132 return getSectionContentsAsArray<Elf_Sym>(Sec);
135 Expected<Elf_Rela_Range> relas(const Elf_Shdr *Sec) const {
136 return getSectionContentsAsArray<Elf_Rela>(Sec);
139 Expected<Elf_Rel_Range> rels(const Elf_Shdr *Sec) const {
140 return getSectionContentsAsArray<Elf_Rel>(Sec);
143 /// \brief Iterate over program header table.
144 Expected<Elf_Phdr_Range> program_headers() const {
145 if (getHeader()->e_phnum && getHeader()->e_phentsize != sizeof(Elf_Phdr))
146 return createError("invalid e_phentsize");
148 reinterpret_cast<const Elf_Phdr *>(base() + getHeader()->e_phoff);
149 return makeArrayRef(Begin, Begin + getHeader()->e_phnum);
152 Expected<StringRef> getSectionStringTable(Elf_Shdr_Range Sections) const;
153 Expected<uint32_t> getSectionIndex(const Elf_Sym *Sym, Elf_Sym_Range Syms,
154 ArrayRef<Elf_Word> ShndxTable) const;
155 Expected<const Elf_Shdr *> getSection(const Elf_Sym *Sym,
156 const Elf_Shdr *SymTab,
157 ArrayRef<Elf_Word> ShndxTable) const;
158 Expected<const Elf_Shdr *> getSection(const Elf_Sym *Sym,
159 Elf_Sym_Range Symtab,
160 ArrayRef<Elf_Word> ShndxTable) const;
161 Expected<const Elf_Shdr *> getSection(uint32_t Index) const;
163 Expected<const Elf_Sym *> getSymbol(const Elf_Shdr *Sec,
164 uint32_t Index) const;
166 Expected<StringRef> getSectionName(const Elf_Shdr *Section) const;
167 Expected<StringRef> getSectionName(const Elf_Shdr *Section,
168 StringRef DotShstrtab) const;
169 template <typename T>
170 Expected<ArrayRef<T>> getSectionContentsAsArray(const Elf_Shdr *Sec) const;
171 Expected<ArrayRef<uint8_t>> getSectionContents(const Elf_Shdr *Sec) const;
174 using ELF32LEFile = ELFFile<ELFType<support::little, false>>;
175 using ELF64LEFile = ELFFile<ELFType<support::little, true>>;
176 using ELF32BEFile = ELFFile<ELFType<support::big, false>>;
177 using ELF64BEFile = ELFFile<ELFType<support::big, true>>;
179 template <class ELFT>
180 inline Expected<const typename ELFT::Shdr *>
181 getSection(typename ELFT::ShdrRange Sections, uint32_t Index) {
182 if (Index >= Sections.size())
183 return createError("invalid section index");
184 return &Sections[Index];
187 template <class ELFT>
188 inline Expected<uint32_t>
189 getExtendedSymbolTableIndex(const typename ELFT::Sym *Sym,
190 const typename ELFT::Sym *FirstSym,
191 ArrayRef<typename ELFT::Word> ShndxTable) {
192 assert(Sym->st_shndx == ELF::SHN_XINDEX);
193 unsigned Index = Sym - FirstSym;
194 if (Index >= ShndxTable.size())
195 return createError("index past the end of the symbol table");
197 // The size of the table was checked in getSHNDXTable.
198 return ShndxTable[Index];
201 template <class ELFT>
203 ELFFile<ELFT>::getSectionIndex(const Elf_Sym *Sym, Elf_Sym_Range Syms,
204 ArrayRef<Elf_Word> ShndxTable) const {
205 uint32_t Index = Sym->st_shndx;
206 if (Index == ELF::SHN_XINDEX) {
207 auto ErrorOrIndex = getExtendedSymbolTableIndex<ELFT>(
208 Sym, Syms.begin(), ShndxTable);
210 return ErrorOrIndex.takeError();
211 return *ErrorOrIndex;
213 if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE)
218 template <class ELFT>
219 Expected<const typename ELFT::Shdr *>
220 ELFFile<ELFT>::getSection(const Elf_Sym *Sym, const Elf_Shdr *SymTab,
221 ArrayRef<Elf_Word> ShndxTable) const {
222 auto SymsOrErr = symbols(SymTab);
224 return SymsOrErr.takeError();
225 return getSection(Sym, *SymsOrErr, ShndxTable);
228 template <class ELFT>
229 Expected<const typename ELFT::Shdr *>
230 ELFFile<ELFT>::getSection(const Elf_Sym *Sym, Elf_Sym_Range Symbols,
231 ArrayRef<Elf_Word> ShndxTable) const {
232 auto IndexOrErr = getSectionIndex(Sym, Symbols, ShndxTable);
234 return IndexOrErr.takeError();
235 uint32_t Index = *IndexOrErr;
238 auto SectionsOrErr = sections();
240 return SectionsOrErr.takeError();
241 return object::getSection<ELFT>(*SectionsOrErr, Index);
244 template <class ELFT>
245 inline Expected<const typename ELFT::Sym *>
246 getSymbol(typename ELFT::SymRange Symbols, uint32_t Index) {
247 if (Index >= Symbols.size())
248 return createError("invalid symbol index");
249 return &Symbols[Index];
252 template <class ELFT>
253 Expected<const typename ELFT::Sym *>
254 ELFFile<ELFT>::getSymbol(const Elf_Shdr *Sec, uint32_t Index) const {
255 auto SymtabOrErr = symbols(Sec);
257 return SymtabOrErr.takeError();
258 return object::getSymbol<ELFT>(*SymtabOrErr, Index);
261 template <class ELFT>
262 template <typename T>
263 Expected<ArrayRef<T>>
264 ELFFile<ELFT>::getSectionContentsAsArray(const Elf_Shdr *Sec) const {
265 if (Sec->sh_entsize != sizeof(T) && sizeof(T) != 1)
266 return createError("invalid sh_entsize");
268 uintX_t Offset = Sec->sh_offset;
269 uintX_t Size = Sec->sh_size;
271 if (Size % sizeof(T))
272 return createError("size is not a multiple of sh_entsize");
273 if ((std::numeric_limits<uintX_t>::max() - Offset < Size) ||
274 Offset + Size > Buf.size())
275 return createError("invalid section offset");
277 const T *Start = reinterpret_cast<const T *>(base() + Offset);
278 return makeArrayRef(Start, Size / sizeof(T));
281 template <class ELFT>
282 Expected<ArrayRef<uint8_t>>
283 ELFFile<ELFT>::getSectionContents(const Elf_Shdr *Sec) const {
284 return getSectionContentsAsArray<uint8_t>(Sec);
287 template <class ELFT>
288 StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
289 return getELFRelocationTypeName(getHeader()->e_machine, Type);
292 template <class ELFT>
293 void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type,
294 SmallVectorImpl<char> &Result) const {
295 if (!isMipsELF64()) {
296 StringRef Name = getRelocationTypeName(Type);
297 Result.append(Name.begin(), Name.end());
299 // The Mips N64 ABI allows up to three operations to be specified per
300 // relocation record. Unfortunately there's no easy way to test for the
301 // presence of N64 ELFs as they have no special flag that identifies them
302 // as being N64. We can safely assume at the moment that all Mips
303 // ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough
304 // information to disambiguate between old vs new ABIs.
305 uint8_t Type1 = (Type >> 0) & 0xFF;
306 uint8_t Type2 = (Type >> 8) & 0xFF;
307 uint8_t Type3 = (Type >> 16) & 0xFF;
309 // Concat all three relocation type names.
310 StringRef Name = getRelocationTypeName(Type1);
311 Result.append(Name.begin(), Name.end());
313 Name = getRelocationTypeName(Type2);
314 Result.append(1, '/');
315 Result.append(Name.begin(), Name.end());
317 Name = getRelocationTypeName(Type3);
318 Result.append(1, '/');
319 Result.append(Name.begin(), Name.end());
323 template <class ELFT>
324 Expected<const typename ELFT::Sym *>
325 ELFFile<ELFT>::getRelocationSymbol(const Elf_Rel *Rel,
326 const Elf_Shdr *SymTab) const {
327 uint32_t Index = Rel->getSymbol(isMips64EL());
330 return getEntry<Elf_Sym>(SymTab, Index);
333 template <class ELFT>
335 ELFFile<ELFT>::getSectionStringTable(Elf_Shdr_Range Sections) const {
336 uint32_t Index = getHeader()->e_shstrndx;
337 if (Index == ELF::SHN_XINDEX)
338 Index = Sections[0].sh_link;
340 if (!Index) // no section string table.
342 if (Index >= Sections.size())
343 return createError("invalid section index");
344 return getStringTable(&Sections[Index]);
347 template <class ELFT>
348 ELFFile<ELFT>::ELFFile(StringRef Object) : Buf(Object) {
349 assert(sizeof(Elf_Ehdr) <= Buf.size() && "Invalid buffer");
352 template <class ELFT>
353 bool compareAddr(uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *Phdr) {
354 return VAddr < Phdr->p_vaddr;
357 template <class ELFT>
358 Expected<typename ELFT::ShdrRange> ELFFile<ELFT>::sections() const {
359 const uintX_t SectionTableOffset = getHeader()->e_shoff;
360 if (SectionTableOffset == 0)
361 return ArrayRef<Elf_Shdr>();
363 if (getHeader()->e_shentsize != sizeof(Elf_Shdr))
365 "invalid section header entry size (e_shentsize) in ELF header");
367 const uint64_t FileSize = Buf.size();
369 if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize)
370 return createError("section header table goes past the end of the file");
372 // Invalid address alignment of section headers
373 if (SectionTableOffset & (alignof(Elf_Shdr) - 1))
374 return createError("invalid alignment of section headers");
376 const Elf_Shdr *First =
377 reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
379 uintX_t NumSections = getHeader()->e_shnum;
380 if (NumSections == 0)
381 NumSections = First->sh_size;
383 if (NumSections > UINT64_MAX / sizeof(Elf_Shdr))
384 return createError("section table goes past the end of file");
386 const uint64_t SectionTableSize = NumSections * sizeof(Elf_Shdr);
388 // Section table goes past end of file!
389 if (SectionTableOffset + SectionTableSize > FileSize)
390 return createError("section table goes past the end of file");
392 return makeArrayRef(First, NumSections);
395 template <class ELFT>
396 template <typename T>
397 Expected<const T *> ELFFile<ELFT>::getEntry(uint32_t Section,
398 uint32_t Entry) const {
399 auto SecOrErr = getSection(Section);
401 return SecOrErr.takeError();
402 return getEntry<T>(*SecOrErr, Entry);
405 template <class ELFT>
406 template <typename T>
407 Expected<const T *> ELFFile<ELFT>::getEntry(const Elf_Shdr *Section,
408 uint32_t Entry) const {
409 if (sizeof(T) != Section->sh_entsize)
410 return createError("invalid sh_entsize");
411 size_t Pos = Section->sh_offset + Entry * sizeof(T);
412 if (Pos + sizeof(T) > Buf.size())
413 return createError("invalid section offset");
414 return reinterpret_cast<const T *>(base() + Pos);
417 template <class ELFT>
418 Expected<const typename ELFT::Shdr *>
419 ELFFile<ELFT>::getSection(uint32_t Index) const {
420 auto TableOrErr = sections();
422 return TableOrErr.takeError();
423 return object::getSection<ELFT>(*TableOrErr, Index);
426 template <class ELFT>
428 ELFFile<ELFT>::getStringTable(const Elf_Shdr *Section) const {
429 if (Section->sh_type != ELF::SHT_STRTAB)
430 return createError("invalid sh_type for string table, expected SHT_STRTAB");
431 auto V = getSectionContentsAsArray<char>(Section);
433 return V.takeError();
434 ArrayRef<char> Data = *V;
436 return createError("empty string table");
437 if (Data.back() != '\0')
438 return createError("string table non-null terminated");
439 return StringRef(Data.begin(), Data.size());
442 template <class ELFT>
443 Expected<ArrayRef<typename ELFT::Word>>
444 ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section) const {
445 auto SectionsOrErr = sections();
447 return SectionsOrErr.takeError();
448 return getSHNDXTable(Section, *SectionsOrErr);
451 template <class ELFT>
452 Expected<ArrayRef<typename ELFT::Word>>
453 ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section,
454 Elf_Shdr_Range Sections) const {
455 assert(Section.sh_type == ELF::SHT_SYMTAB_SHNDX);
456 auto VOrErr = getSectionContentsAsArray<Elf_Word>(&Section);
458 return VOrErr.takeError();
459 ArrayRef<Elf_Word> V = *VOrErr;
460 auto SymTableOrErr = object::getSection<ELFT>(Sections, Section.sh_link);
462 return SymTableOrErr.takeError();
463 const Elf_Shdr &SymTable = **SymTableOrErr;
464 if (SymTable.sh_type != ELF::SHT_SYMTAB &&
465 SymTable.sh_type != ELF::SHT_DYNSYM)
466 return createError("invalid sh_type");
467 if (V.size() != (SymTable.sh_size / sizeof(Elf_Sym)))
468 return createError("invalid section contents size");
472 template <class ELFT>
474 ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const {
475 auto SectionsOrErr = sections();
477 return SectionsOrErr.takeError();
478 return getStringTableForSymtab(Sec, *SectionsOrErr);
481 template <class ELFT>
483 ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec,
484 Elf_Shdr_Range Sections) const {
486 if (Sec.sh_type != ELF::SHT_SYMTAB && Sec.sh_type != ELF::SHT_DYNSYM)
488 "invalid sh_type for symbol table, expected SHT_SYMTAB or SHT_DYNSYM");
489 auto SectionOrErr = object::getSection<ELFT>(Sections, Sec.sh_link);
491 return SectionOrErr.takeError();
492 return getStringTable(*SectionOrErr);
495 template <class ELFT>
497 ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section) const {
498 auto SectionsOrErr = sections();
500 return SectionsOrErr.takeError();
501 auto Table = getSectionStringTable(*SectionsOrErr);
503 return Table.takeError();
504 return getSectionName(Section, *Table);
507 template <class ELFT>
508 Expected<StringRef> ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section,
509 StringRef DotShstrtab) const {
510 uint32_t Offset = Section->sh_name;
513 if (Offset >= DotShstrtab.size())
514 return createError("invalid string offset");
515 return StringRef(DotShstrtab.data() + Offset);
518 /// This function returns the hash value for a symbol in the .dynsym section
519 /// Name of the API remains consistent as specified in the libelf
520 /// REF : http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#hash
521 inline unsigned hashSysV(StringRef SymbolName) {
523 for (char C : SymbolName) {
533 } // end namespace object
534 } // end namespace llvm
536 #endif // LLVM_OBJECT_ELF_H