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llvm-project/llvm/lib/Object/ELF.cpp
Peter Collingbourne aedb4bf37f Object: Move some code from ELF.h into ELF.cpp. 
Differential Revision: https://reviews.llvm.org/D39271

llvm-svn: 317046
2017-10-31 22:49:23 +00:00

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//===- ELF.cpp - ELF object file implementation ---------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Object/ELF.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/Support/LEB128.h"
using namespace llvm;
using namespace object;
#define STRINGIFY_ENUM_CASE(ns, name) \
case ns::name: \
return #name;
#define ELF_RELOC(name, value) STRINGIFY_ENUM_CASE(ELF, name)
StringRef llvm::object::getELFRelocationTypeName(uint32_t Machine,
uint32_t Type) {
switch (Machine) {
case ELF::EM_X86_64:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/x86_64.def"
default:
break;
}
break;
case ELF::EM_386:
case ELF::EM_IAMCU:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/i386.def"
default:
break;
}
break;
case ELF::EM_MIPS:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/Mips.def"
default:
break;
}
break;
case ELF::EM_AARCH64:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/AArch64.def"
default:
break;
}
break;
case ELF::EM_ARM:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/ARM.def"
default:
break;
}
break;
case ELF::EM_ARC_COMPACT:
case ELF::EM_ARC_COMPACT2:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/ARC.def"
default:
break;
}
break;
case ELF::EM_AVR:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/AVR.def"
default:
break;
}
break;
case ELF::EM_HEXAGON:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/Hexagon.def"
default:
break;
}
break;
case ELF::EM_LANAI:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/Lanai.def"
default:
break;
}
break;
case ELF::EM_PPC:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/PowerPC.def"
default:
break;
}
break;
case ELF::EM_PPC64:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/PowerPC64.def"
default:
break;
}
break;
case ELF::EM_RISCV:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/RISCV.def"
default:
break;
}
break;
case ELF::EM_S390:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/SystemZ.def"
default:
break;
}
break;
case ELF::EM_SPARC:
case ELF::EM_SPARC32PLUS:
case ELF::EM_SPARCV9:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/Sparc.def"
default:
break;
}
break;
case ELF::EM_WEBASSEMBLY:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/WebAssembly.def"
default:
break;
}
break;
case ELF::EM_AMDGPU:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/AMDGPU.def"
default:
break;
}
case ELF::EM_BPF:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/BPF.def"
default:
break;
}
break;
default:
break;
}
return "Unknown";
}
#undef ELF_RELOC
StringRef llvm::object::getELFSectionTypeName(uint32_t Machine, unsigned Type) {
switch (Machine) {
case ELF::EM_ARM:
switch (Type) {
STRINGIFY_ENUM_CASE(ELF, SHT_ARM_EXIDX);
STRINGIFY_ENUM_CASE(ELF, SHT_ARM_PREEMPTMAP);
STRINGIFY_ENUM_CASE(ELF, SHT_ARM_ATTRIBUTES);
STRINGIFY_ENUM_CASE(ELF, SHT_ARM_DEBUGOVERLAY);
STRINGIFY_ENUM_CASE(ELF, SHT_ARM_OVERLAYSECTION);
}
break;
case ELF::EM_HEXAGON:
switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_HEX_ORDERED); }
break;
case ELF::EM_X86_64:
switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_X86_64_UNWIND); }
break;
case ELF::EM_MIPS:
case ELF::EM_MIPS_RS3_LE:
switch (Type) {
STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_REGINFO);
STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_OPTIONS);
STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_ABIFLAGS);
STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_DWARF);
}
break;
default:
break;
}
switch (Type) {
STRINGIFY_ENUM_CASE(ELF, SHT_NULL);
STRINGIFY_ENUM_CASE(ELF, SHT_PROGBITS);
STRINGIFY_ENUM_CASE(ELF, SHT_SYMTAB);
STRINGIFY_ENUM_CASE(ELF, SHT_STRTAB);
STRINGIFY_ENUM_CASE(ELF, SHT_RELA);
STRINGIFY_ENUM_CASE(ELF, SHT_HASH);
STRINGIFY_ENUM_CASE(ELF, SHT_DYNAMIC);
STRINGIFY_ENUM_CASE(ELF, SHT_NOTE);
STRINGIFY_ENUM_CASE(ELF, SHT_NOBITS);
STRINGIFY_ENUM_CASE(ELF, SHT_REL);
STRINGIFY_ENUM_CASE(ELF, SHT_SHLIB);
STRINGIFY_ENUM_CASE(ELF, SHT_DYNSYM);
STRINGIFY_ENUM_CASE(ELF, SHT_INIT_ARRAY);
STRINGIFY_ENUM_CASE(ELF, SHT_FINI_ARRAY);
STRINGIFY_ENUM_CASE(ELF, SHT_PREINIT_ARRAY);
STRINGIFY_ENUM_CASE(ELF, SHT_GROUP);
STRINGIFY_ENUM_CASE(ELF, SHT_SYMTAB_SHNDX);
STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_REL);
STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_RELA);
STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_ODRTAB);
STRINGIFY_ENUM_CASE(ELF, SHT_GNU_ATTRIBUTES);
STRINGIFY_ENUM_CASE(ELF, SHT_GNU_HASH);
STRINGIFY_ENUM_CASE(ELF, SHT_GNU_verdef);
STRINGIFY_ENUM_CASE(ELF, SHT_GNU_verneed);
STRINGIFY_ENUM_CASE(ELF, SHT_GNU_versym);
default:
return "Unknown";
}
}
template <class ELFT>
Expected<uint32_t>
ELFFile<ELFT>::getSectionIndex(const Elf_Sym *Sym, Elf_Sym_Range Syms,
ArrayRef<Elf_Word> ShndxTable) const {
uint32_t Index = Sym->st_shndx;
if (Index == ELF::SHN_XINDEX) {
auto ErrorOrIndex = getExtendedSymbolTableIndex<ELFT>(
Sym, Syms.begin(), ShndxTable);
if (!ErrorOrIndex)
return ErrorOrIndex.takeError();
return *ErrorOrIndex;
}
if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE)
return 0;
return Index;
}
template <class ELFT>
Expected<const typename ELFT::Shdr *>
ELFFile<ELFT>::getSection(const Elf_Sym *Sym, const Elf_Shdr *SymTab,
ArrayRef<Elf_Word> ShndxTable) const {
auto SymsOrErr = symbols(SymTab);
if (!SymsOrErr)
return SymsOrErr.takeError();
return getSection(Sym, *SymsOrErr, ShndxTable);
}
template <class ELFT>
Expected<const typename ELFT::Shdr *>
ELFFile<ELFT>::getSection(const Elf_Sym *Sym, Elf_Sym_Range Symbols,
ArrayRef<Elf_Word> ShndxTable) const {
auto IndexOrErr = getSectionIndex(Sym, Symbols, ShndxTable);
if (!IndexOrErr)
return IndexOrErr.takeError();
uint32_t Index = *IndexOrErr;
if (Index == 0)
return nullptr;
return getSection(Index);
}
template <class ELFT>
Expected<const typename ELFT::Sym *>
ELFFile<ELFT>::getSymbol(const Elf_Shdr *Sec, uint32_t Index) const {
auto SymtabOrErr = symbols(Sec);
if (!SymtabOrErr)
return SymtabOrErr.takeError();
return object::getSymbol<ELFT>(*SymtabOrErr, Index);
}
template <class ELFT>
Expected<ArrayRef<uint8_t>>
ELFFile<ELFT>::getSectionContents(const Elf_Shdr *Sec) const {
return getSectionContentsAsArray<uint8_t>(Sec);
}
template <class ELFT>
StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
return getELFRelocationTypeName(getHeader()->e_machine, Type);
}
template <class ELFT>
void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type,
SmallVectorImpl<char> &Result) const {
if (!isMipsELF64()) {
StringRef Name = getRelocationTypeName(Type);
Result.append(Name.begin(), Name.end());
} else {
// The Mips N64 ABI allows up to three operations to be specified per
// relocation record. Unfortunately there's no easy way to test for the
// presence of N64 ELFs as they have no special flag that identifies them
// as being N64. We can safely assume at the moment that all Mips
// ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough
// information to disambiguate between old vs new ABIs.
uint8_t Type1 = (Type >> 0) & 0xFF;
uint8_t Type2 = (Type >> 8) & 0xFF;
uint8_t Type3 = (Type >> 16) & 0xFF;
// Concat all three relocation type names.
StringRef Name = getRelocationTypeName(Type1);
Result.append(Name.begin(), Name.end());
Name = getRelocationTypeName(Type2);
Result.append(1, '/');
Result.append(Name.begin(), Name.end());
Name = getRelocationTypeName(Type3);
Result.append(1, '/');
Result.append(Name.begin(), Name.end());
}
}
template <class ELFT>
Expected<const typename ELFT::Sym *>
ELFFile<ELFT>::getRelocationSymbol(const Elf_Rel *Rel,
const Elf_Shdr *SymTab) const {
uint32_t Index = Rel->getSymbol(isMips64EL());
if (Index == 0)
return nullptr;
return getEntry<Elf_Sym>(SymTab, Index);
}
template <class ELFT>
Expected<StringRef>
ELFFile<ELFT>::getSectionStringTable(Elf_Shdr_Range Sections) const {
uint32_t Index = getHeader()->e_shstrndx;
if (Index == ELF::SHN_XINDEX)
Index = Sections[0].sh_link;
if (!Index) // no section string table.
return "";
if (Index >= Sections.size())
return createError("invalid section index");
return getStringTable(&Sections[Index]);
}
template <class ELFT> ELFFile<ELFT>::ELFFile(StringRef Object) : Buf(Object) {}
template <class ELFT>
Expected<ELFFile<ELFT>> ELFFile<ELFT>::create(StringRef Object) {
if (sizeof(Elf_Ehdr) > Object.size())
return createError("Invalid buffer");
return ELFFile(Object);
}
template <class ELFT>
Expected<typename ELFT::ShdrRange> ELFFile<ELFT>::sections() const {
const uintX_t SectionTableOffset = getHeader()->e_shoff;
if (SectionTableOffset == 0)
return ArrayRef<Elf_Shdr>();
if (getHeader()->e_shentsize != sizeof(Elf_Shdr))
return createError(
"invalid section header entry size (e_shentsize) in ELF header");
const uint64_t FileSize = Buf.size();
if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize)
return createError("section header table goes past the end of the file");
// Invalid address alignment of section headers
if (SectionTableOffset & (alignof(Elf_Shdr) - 1))
return createError("invalid alignment of section headers");
const Elf_Shdr *First =
reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
uintX_t NumSections = getHeader()->e_shnum;
if (NumSections == 0)
NumSections = First->sh_size;
if (NumSections > UINT64_MAX / sizeof(Elf_Shdr))
return createError("section table goes past the end of file");
const uint64_t SectionTableSize = NumSections * sizeof(Elf_Shdr);
// Section table goes past end of file!
if (SectionTableOffset + SectionTableSize > FileSize)
return createError("section table goes past the end of file");
return makeArrayRef(First, NumSections);
}
template <class ELFT>
Expected<const typename ELFT::Shdr *>
ELFFile<ELFT>::getSection(uint32_t Index) const {
auto TableOrErr = sections();
if (!TableOrErr)
return TableOrErr.takeError();
return object::getSection<ELFT>(*TableOrErr, Index);
}
template <class ELFT>
Expected<StringRef>
ELFFile<ELFT>::getStringTable(const Elf_Shdr *Section) const {
if (Section->sh_type != ELF::SHT_STRTAB)
return createError("invalid sh_type for string table, expected SHT_STRTAB");
auto V = getSectionContentsAsArray<char>(Section);
if (!V)
return V.takeError();
ArrayRef<char> Data = *V;
if (Data.empty())
return createError("empty string table");
if (Data.back() != '\0')
return createError("string table non-null terminated");
return StringRef(Data.begin(), Data.size());
}
template <class ELFT>
Expected<ArrayRef<typename ELFT::Word>>
ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section) const {
auto SectionsOrErr = sections();
if (!SectionsOrErr)
return SectionsOrErr.takeError();
return getSHNDXTable(Section, *SectionsOrErr);
}
template <class ELFT>
Expected<ArrayRef<typename ELFT::Word>>
ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section,
Elf_Shdr_Range Sections) const {
assert(Section.sh_type == ELF::SHT_SYMTAB_SHNDX);
auto VOrErr = getSectionContentsAsArray<Elf_Word>(&Section);
if (!VOrErr)
return VOrErr.takeError();
ArrayRef<Elf_Word> V = *VOrErr;
auto SymTableOrErr = object::getSection<ELFT>(Sections, Section.sh_link);
if (!SymTableOrErr)
return SymTableOrErr.takeError();
const Elf_Shdr &SymTable = **SymTableOrErr;
if (SymTable.sh_type != ELF::SHT_SYMTAB &&
SymTable.sh_type != ELF::SHT_DYNSYM)
return createError("invalid sh_type");
if (V.size() != (SymTable.sh_size / sizeof(Elf_Sym)))
return createError("invalid section contents size");
return V;
}
template <class ELFT>
Expected<StringRef>
ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const {
auto SectionsOrErr = sections();
if (!SectionsOrErr)
return SectionsOrErr.takeError();
return getStringTableForSymtab(Sec, *SectionsOrErr);
}
template <class ELFT>
Expected<StringRef>
ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec,
Elf_Shdr_Range Sections) const {
if (Sec.sh_type != ELF::SHT_SYMTAB && Sec.sh_type != ELF::SHT_DYNSYM)
return createError(
"invalid sh_type for symbol table, expected SHT_SYMTAB or SHT_DYNSYM");
auto SectionOrErr = object::getSection<ELFT>(Sections, Sec.sh_link);
if (!SectionOrErr)
return SectionOrErr.takeError();
return getStringTable(*SectionOrErr);
}
template <class ELFT>
Expected<StringRef>
ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section) const {
auto SectionsOrErr = sections();
if (!SectionsOrErr)
return SectionsOrErr.takeError();
auto Table = getSectionStringTable(*SectionsOrErr);
if (!Table)
return Table.takeError();
return getSectionName(Section, *Table);
}
template <class ELFT>
Expected<StringRef> ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section,
StringRef DotShstrtab) const {
uint32_t Offset = Section->sh_name;
if (Offset == 0)
return StringRef();
if (Offset >= DotShstrtab.size())
return createError("invalid string offset");
return StringRef(DotShstrtab.data() + Offset);
}
template <class ELFT>
Expected<std::vector<typename ELFT::Rela>>
ELFFile<ELFT>::android_relas(const Elf_Shdr *Sec) const {
// This function reads relocations in Android's packed relocation format,
// which is based on SLEB128 and delta encoding.
Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
if (!ContentsOrErr)
return ContentsOrErr.takeError();
const uint8_t *Cur = ContentsOrErr->begin();
const uint8_t *End = ContentsOrErr->end();
if (ContentsOrErr->size() < 4 || Cur[0] != 'A' || Cur[1] != 'P' ||
Cur[2] != 'S' || Cur[3] != '2')
return createError("invalid packed relocation header");
Cur += 4;
const char *ErrStr = nullptr;
auto ReadSLEB = [&]() -> int64_t {
if (ErrStr)
return 0;
unsigned Len;
int64_t Result = decodeSLEB128(Cur, &Len, End, &ErrStr);
Cur += Len;
return Result;
};
uint64_t NumRelocs = ReadSLEB();
uint64_t Offset = ReadSLEB();
uint64_t Addend = 0;
if (ErrStr)
return createError(ErrStr);
std::vector<Elf_Rela> Relocs;
Relocs.reserve(NumRelocs);
while (NumRelocs) {
uint64_t NumRelocsInGroup = ReadSLEB();
if (NumRelocsInGroup > NumRelocs)
return createError("relocation group unexpectedly large");
NumRelocs -= NumRelocsInGroup;
uint64_t GroupFlags = ReadSLEB();
bool GroupedByInfo = GroupFlags & ELF::RELOCATION_GROUPED_BY_INFO_FLAG;
bool GroupedByOffsetDelta = GroupFlags & ELF::RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG;
bool GroupedByAddend = GroupFlags & ELF::RELOCATION_GROUPED_BY_ADDEND_FLAG;
bool GroupHasAddend = GroupFlags & ELF::RELOCATION_GROUP_HAS_ADDEND_FLAG;
uint64_t GroupOffsetDelta;
if (GroupedByOffsetDelta)
GroupOffsetDelta = ReadSLEB();
uint64_t GroupRInfo;
if (GroupedByInfo)
GroupRInfo = ReadSLEB();
if (GroupedByAddend && GroupHasAddend)
Addend += ReadSLEB();
for (uint64_t I = 0; I != NumRelocsInGroup; ++I) {
Elf_Rela R;
Offset += GroupedByOffsetDelta ? GroupOffsetDelta : ReadSLEB();
R.r_offset = Offset;
R.r_info = GroupedByInfo ? GroupRInfo : ReadSLEB();
if (GroupHasAddend) {
if (!GroupedByAddend)
Addend += ReadSLEB();
R.r_addend = Addend;
} else {
R.r_addend = 0;
}
Relocs.push_back(R);
if (ErrStr)
return createError(ErrStr);
}
if (ErrStr)
return createError(ErrStr);
}
return Relocs;
}
template class llvm::object::ELFFile<ELF32LE>;
template class llvm::object::ELFFile<ELF32BE>;
template class llvm::object::ELFFile<ELF64LE>;
template class llvm::object::ELFFile<ELF64BE>;
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