475 lines
15 KiB
C++
475 lines
15 KiB
C++
//===- InputFiles.cpp -----------------------------------------------------===//
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//
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// The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "InputFiles.h"
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#include "InputSection.h"
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#include "Error.h"
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#include "Symbols.h"
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#include "llvm/ADT/STLExtras.h"
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using namespace llvm;
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using namespace llvm::ELF;
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using namespace llvm::object;
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using namespace llvm::sys::fs;
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using namespace lld;
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using namespace lld::elf2;
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namespace {
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class ECRAII {
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std::error_code EC;
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public:
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std::error_code &getEC() { return EC; }
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~ECRAII() { error(EC); }
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};
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}
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template <class ELFT>
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ELFFileBase<ELFT>::ELFFileBase(Kind K, MemoryBufferRef M)
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: InputFile(K, M), ELFObj(MB.getBuffer(), ECRAII().getEC()) {}
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template <class ELFT>
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ELFKind ELFFileBase<ELFT>::getELFKind() {
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using llvm::support::little;
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if (ELFT::Is64Bits)
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return ELFT::TargetEndianness == little ? ELF64LEKind : ELF64BEKind;
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return ELFT::TargetEndianness == little ? ELF32LEKind : ELF32BEKind;
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}
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template <class ELFT>
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typename ELFFileBase<ELFT>::Elf_Sym_Range
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ELFFileBase<ELFT>::getSymbolsHelper(bool Local) {
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if (!Symtab)
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return Elf_Sym_Range(nullptr, nullptr);
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Elf_Sym_Range Syms = ELFObj.symbols(Symtab);
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uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
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uint32_t FirstNonLocal = Symtab->sh_info;
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if (FirstNonLocal > NumSymbols)
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error("Invalid sh_info in symbol table");
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if (!Local)
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return make_range(Syms.begin() + FirstNonLocal, Syms.end());
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// +1 to skip over dummy symbol.
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return make_range(Syms.begin() + 1, Syms.begin() + FirstNonLocal);
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}
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template <class ELFT>
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uint32_t ELFFileBase<ELFT>::getSectionIndex(const Elf_Sym &Sym) const {
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uint32_t Index = Sym.st_shndx;
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if (Index == ELF::SHN_XINDEX)
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Index = this->ELFObj.getExtendedSymbolTableIndex(&Sym, this->Symtab,
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SymtabSHNDX);
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else if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE)
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return 0;
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if (!Index)
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error("Invalid section index");
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return Index;
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}
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template <class ELFT> void ELFFileBase<ELFT>::initStringTable() {
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if (!Symtab)
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return;
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ErrorOr<StringRef> StringTableOrErr = ELFObj.getStringTableForSymtab(*Symtab);
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error(StringTableOrErr.getError());
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StringTable = *StringTableOrErr;
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}
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template <class ELFT>
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typename ELFFileBase<ELFT>::Elf_Sym_Range
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ELFFileBase<ELFT>::getNonLocalSymbols() {
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return getSymbolsHelper(false);
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}
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template <class ELFT>
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ObjectFile<ELFT>::ObjectFile(MemoryBufferRef M)
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: ELFFileBase<ELFT>(Base::ObjectKind, M) {}
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template <class ELFT>
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typename ObjectFile<ELFT>::Elf_Sym_Range ObjectFile<ELFT>::getLocalSymbols() {
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return this->getSymbolsHelper(true);
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}
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template <class ELFT>
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const typename ObjectFile<ELFT>::Elf_Sym *
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ObjectFile<ELFT>::getLocalSymbol(uintX_t SymIndex) {
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uint32_t FirstNonLocal = this->Symtab->sh_info;
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if (SymIndex >= FirstNonLocal)
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return nullptr;
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Elf_Sym_Range Syms = this->ELFObj.symbols(this->Symtab);
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return Syms.begin() + SymIndex;
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}
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template <class ELFT>
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void elf2::ObjectFile<ELFT>::parse(DenseSet<StringRef> &Comdats) {
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// Read section and symbol tables.
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initializeSections(Comdats);
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initializeSymbols();
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}
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template <class ELFT>
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StringRef ObjectFile<ELFT>::getShtGroupSignature(const Elf_Shdr &Sec) {
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const ELFFile<ELFT> &Obj = this->ELFObj;
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uint32_t SymtabdSectionIndex = Sec.sh_link;
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ErrorOr<const Elf_Shdr *> SecOrErr = Obj.getSection(SymtabdSectionIndex);
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error(SecOrErr);
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const Elf_Shdr *SymtabSec = *SecOrErr;
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uint32_t SymIndex = Sec.sh_info;
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const Elf_Sym *Sym = Obj.getSymbol(SymtabSec, SymIndex);
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ErrorOr<StringRef> StringTableOrErr = Obj.getStringTableForSymtab(*SymtabSec);
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error(StringTableOrErr);
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ErrorOr<StringRef> SignatureOrErr = Sym->getName(*StringTableOrErr);
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error(SignatureOrErr);
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return *SignatureOrErr;
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}
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template <class ELFT>
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ArrayRef<typename ObjectFile<ELFT>::GroupEntryType>
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ObjectFile<ELFT>::getShtGroupEntries(const Elf_Shdr &Sec) {
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const ELFFile<ELFT> &Obj = this->ELFObj;
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ErrorOr<ArrayRef<GroupEntryType>> EntriesOrErr =
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Obj.template getSectionContentsAsArray<GroupEntryType>(&Sec);
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error(EntriesOrErr.getError());
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ArrayRef<GroupEntryType> Entries = *EntriesOrErr;
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if (Entries.empty() || Entries[0] != GRP_COMDAT)
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error("Unsupported SHT_GROUP format");
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return Entries.slice(1);
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}
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template <class ELFT>
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static bool shouldMerge(const typename ELFFile<ELFT>::Elf_Shdr &Sec) {
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typedef typename ELFFile<ELFT>::uintX_t uintX_t;
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uintX_t Flags = Sec.sh_flags;
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if (!(Flags & SHF_MERGE))
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return false;
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if (Flags & SHF_WRITE)
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error("Writable SHF_MERGE sections are not supported");
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uintX_t EntSize = Sec.sh_entsize;
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if (!EntSize || Sec.sh_size % EntSize)
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error("SHF_MERGE section size must be a multiple of sh_entsize");
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// Don't try to merge if the aligment is larger than the sh_entsize.
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//
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// If this is not a SHF_STRINGS, we would need to pad after every entity. It
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// would be equivalent for the producer of the .o to just set a larger
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// sh_entsize.
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//
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// If this is a SHF_STRINGS, the larger alignment makes sense. Unfortunately
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// it would complicate tail merging. This doesn't seem that common to
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// justify the effort.
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if (Sec.sh_addralign > EntSize)
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return false;
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return true;
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}
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template <class ELFT>
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void elf2::ObjectFile<ELFT>::initializeSections(DenseSet<StringRef> &Comdats) {
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uint64_t Size = this->ELFObj.getNumSections();
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Sections.resize(Size);
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unsigned I = -1;
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const ELFFile<ELFT> &Obj = this->ELFObj;
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for (const Elf_Shdr &Sec : Obj.sections()) {
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++I;
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if (Sections[I] == &InputSection<ELFT>::Discarded)
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continue;
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switch (Sec.sh_type) {
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case SHT_GROUP:
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Sections[I] = &InputSection<ELFT>::Discarded;
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if (Comdats.insert(getShtGroupSignature(Sec)).second)
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continue;
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for (GroupEntryType E : getShtGroupEntries(Sec)) {
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uint32_t SecIndex = E;
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if (SecIndex >= Size)
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error("Invalid section index in group");
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Sections[SecIndex] = &InputSection<ELFT>::Discarded;
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}
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break;
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case SHT_SYMTAB:
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this->Symtab = &Sec;
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break;
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case SHT_SYMTAB_SHNDX: {
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ErrorOr<ArrayRef<Elf_Word>> ErrorOrTable = Obj.getSHNDXTable(Sec);
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error(ErrorOrTable);
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this->SymtabSHNDX = *ErrorOrTable;
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break;
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}
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case SHT_STRTAB:
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case SHT_NULL:
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break;
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case SHT_RELA:
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case SHT_REL: {
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uint32_t RelocatedSectionIndex = Sec.sh_info;
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if (RelocatedSectionIndex >= Size)
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error("Invalid relocated section index");
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InputSectionBase<ELFT> *RelocatedSection =
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Sections[RelocatedSectionIndex];
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if (!RelocatedSection)
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error("Unsupported relocation reference");
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if (auto *S = dyn_cast<InputSection<ELFT>>(RelocatedSection)) {
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S->RelocSections.push_back(&Sec);
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} else if (auto *S = dyn_cast<EHInputSection<ELFT>>(RelocatedSection)) {
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if (S->RelocSection)
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error("Multiple relocation sections to .eh_frame are not supported");
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S->RelocSection = &Sec;
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} else {
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error("Relocations pointing to SHF_MERGE are not supported");
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}
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break;
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}
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default:
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ErrorOr<StringRef> NameOrErr = this->ELFObj.getSectionName(&Sec);
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error(NameOrErr);
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StringRef Name = *NameOrErr;
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if (Name == ".note.GNU-stack")
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Sections[I] = &InputSection<ELFT>::Discarded;
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else if (Name == ".eh_frame")
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Sections[I] = new (this->Alloc) EHInputSection<ELFT>(this, &Sec);
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else if (shouldMerge<ELFT>(Sec))
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Sections[I] = new (this->Alloc) MergeInputSection<ELFT>(this, &Sec);
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else
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Sections[I] = new (this->Alloc) InputSection<ELFT>(this, &Sec);
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break;
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}
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}
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}
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template <class ELFT> void elf2::ObjectFile<ELFT>::initializeSymbols() {
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this->initStringTable();
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Elf_Sym_Range Syms = this->getNonLocalSymbols();
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uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
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this->SymbolBodies.reserve(NumSymbols);
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for (const Elf_Sym &Sym : Syms)
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this->SymbolBodies.push_back(createSymbolBody(this->StringTable, &Sym));
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}
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template <class ELFT>
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InputSectionBase<ELFT> *
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elf2::ObjectFile<ELFT>::getSection(const Elf_Sym &Sym) const {
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uint32_t Index = this->getSectionIndex(Sym);
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if (Index == 0)
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return nullptr;
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if (Index >= Sections.size() || !Sections[Index])
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error("Invalid section index");
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return Sections[Index];
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}
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template <class ELFT>
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SymbolBody *elf2::ObjectFile<ELFT>::createSymbolBody(StringRef StringTable,
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const Elf_Sym *Sym) {
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ErrorOr<StringRef> NameOrErr = Sym->getName(StringTable);
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error(NameOrErr.getError());
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StringRef Name = *NameOrErr;
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switch (Sym->st_shndx) {
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case SHN_ABS:
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return new (this->Alloc) DefinedAbsolute<ELFT>(Name, *Sym);
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case SHN_UNDEF:
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return new (this->Alloc) Undefined<ELFT>(Name, *Sym);
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case SHN_COMMON:
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return new (this->Alloc) DefinedCommon<ELFT>(Name, *Sym);
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}
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switch (Sym->getBinding()) {
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default:
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error("unexpected binding");
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case STB_GLOBAL:
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case STB_WEAK:
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case STB_GNU_UNIQUE: {
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InputSectionBase<ELFT> *Sec = getSection(*Sym);
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if (Sec == &InputSection<ELFT>::Discarded)
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return new (this->Alloc) Undefined<ELFT>(Name, *Sym);
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return new (this->Alloc) DefinedRegular<ELFT>(Name, *Sym, *Sec);
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}
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}
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}
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static std::unique_ptr<Archive> openArchive(MemoryBufferRef MB) {
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ErrorOr<std::unique_ptr<Archive>> ArchiveOrErr = Archive::create(MB);
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error(ArchiveOrErr, "Failed to parse archive");
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return std::move(*ArchiveOrErr);
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}
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void ArchiveFile::parse() {
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File = openArchive(MB);
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// Allocate a buffer for Lazy objects.
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size_t NumSyms = File->getNumberOfSymbols();
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LazySymbols.reserve(NumSyms);
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// Read the symbol table to construct Lazy objects.
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for (const Archive::Symbol &Sym : File->symbols())
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LazySymbols.emplace_back(this, Sym);
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}
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// Returns a buffer pointing to a member file containing a given symbol.
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MemoryBufferRef ArchiveFile::getMember(const Archive::Symbol *Sym) {
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ErrorOr<Archive::Child> COrErr = Sym->getMember();
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error(COrErr, "Could not get the member for symbol " + Sym->getName());
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const Archive::Child &C = *COrErr;
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if (!Seen.insert(C.getChildOffset()).second)
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return MemoryBufferRef();
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ErrorOr<MemoryBufferRef> Ret = C.getMemoryBufferRef();
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error(Ret, "Could not get the buffer for the member defining symbol " +
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Sym->getName());
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return *Ret;
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}
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std::vector<MemoryBufferRef> ArchiveFile::getMembers() {
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File = openArchive(MB);
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std::vector<MemoryBufferRef> Result;
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for (auto &ChildOrErr : File->children()) {
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error(ChildOrErr,
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"Could not get the child of the archive " + File->getFileName());
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const Archive::Child Child(*ChildOrErr);
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ErrorOr<MemoryBufferRef> MbOrErr = Child.getMemoryBufferRef();
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error(MbOrErr, "Could not get the buffer for a child of the archive " +
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File->getFileName());
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Result.push_back(MbOrErr.get());
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}
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return Result;
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}
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template <class ELFT>
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SharedFile<ELFT>::SharedFile(MemoryBufferRef M)
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: ELFFileBase<ELFT>(Base::SharedKind, M) {
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AsNeeded = Config->AsNeeded;
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}
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template <class ELFT>
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const typename ELFFile<ELFT>::Elf_Shdr *
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SharedFile<ELFT>::getSection(const Elf_Sym &Sym) const {
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uint32_t Index = this->getSectionIndex(Sym);
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if (Index == 0)
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return nullptr;
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ErrorOr<const Elf_Shdr *> Ret = this->ELFObj.getSection(Index);
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error(Ret);
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return *Ret;
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}
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template <class ELFT> void SharedFile<ELFT>::parseSoName() {
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typedef typename ELFFile<ELFT>::Elf_Dyn Elf_Dyn;
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typedef typename ELFFile<ELFT>::uintX_t uintX_t;
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const Elf_Shdr *DynamicSec = nullptr;
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const ELFFile<ELFT> Obj = this->ELFObj;
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for (const Elf_Shdr &Sec : Obj.sections()) {
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switch (Sec.sh_type) {
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default:
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continue;
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case SHT_DYNSYM:
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this->Symtab = &Sec;
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break;
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case SHT_DYNAMIC:
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DynamicSec = &Sec;
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break;
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case SHT_SYMTAB_SHNDX: {
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ErrorOr<ArrayRef<Elf_Word>> ErrorOrTable = Obj.getSHNDXTable(Sec);
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error(ErrorOrTable);
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this->SymtabSHNDX = *ErrorOrTable;
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break;
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}
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}
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}
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this->initStringTable();
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this->SoName = this->getName();
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if (!DynamicSec)
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return;
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auto *Begin =
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reinterpret_cast<const Elf_Dyn *>(Obj.base() + DynamicSec->sh_offset);
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const Elf_Dyn *End = Begin + DynamicSec->sh_size / sizeof(Elf_Dyn);
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for (const Elf_Dyn &Dyn : make_range(Begin, End)) {
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if (Dyn.d_tag == DT_SONAME) {
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uintX_t Val = Dyn.getVal();
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if (Val >= this->StringTable.size())
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error("Invalid DT_SONAME entry");
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this->SoName = StringRef(this->StringTable.data() + Val);
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return;
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}
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}
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}
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template <class ELFT> void SharedFile<ELFT>::parse() {
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Elf_Sym_Range Syms = this->getNonLocalSymbols();
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uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
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SymbolBodies.reserve(NumSymbols);
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for (const Elf_Sym &Sym : Syms) {
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ErrorOr<StringRef> NameOrErr = Sym.getName(this->StringTable);
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error(NameOrErr.getError());
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StringRef Name = *NameOrErr;
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if (Sym.isUndefined())
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Undefs.push_back(Name);
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else
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SymbolBodies.emplace_back(this, Name, Sym);
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}
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}
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template <typename T>
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static std::unique_ptr<InputFile> createELFFileAux(MemoryBufferRef MB) {
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std::unique_ptr<T> Ret = llvm::make_unique<T>(MB);
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if (!Config->FirstElf)
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Config->FirstElf = Ret.get();
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if (Config->EKind == ELFNoneKind) {
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Config->EKind = Ret->getELFKind();
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Config->EMachine = Ret->getEMachine();
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}
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return std::move(Ret);
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}
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template <template <class> class T>
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std::unique_ptr<InputFile> lld::elf2::createELFFile(MemoryBufferRef MB) {
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std::pair<unsigned char, unsigned char> Type = getElfArchType(MB.getBuffer());
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if (Type.second != ELF::ELFDATA2LSB && Type.second != ELF::ELFDATA2MSB)
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error("Invalid data encoding: " + MB.getBufferIdentifier());
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if (Type.first == ELF::ELFCLASS32) {
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if (Type.second == ELF::ELFDATA2LSB)
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return createELFFileAux<T<ELF32LE>>(MB);
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return createELFFileAux<T<ELF32BE>>(MB);
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}
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if (Type.first == ELF::ELFCLASS64) {
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if (Type.second == ELF::ELFDATA2LSB)
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return createELFFileAux<T<ELF64LE>>(MB);
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return createELFFileAux<T<ELF64BE>>(MB);
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}
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error("Invalid file class: " + MB.getBufferIdentifier());
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}
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template class elf2::ELFFileBase<ELF32LE>;
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template class elf2::ELFFileBase<ELF32BE>;
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template class elf2::ELFFileBase<ELF64LE>;
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template class elf2::ELFFileBase<ELF64BE>;
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template class elf2::ObjectFile<ELF32LE>;
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template class elf2::ObjectFile<ELF32BE>;
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template class elf2::ObjectFile<ELF64LE>;
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template class elf2::ObjectFile<ELF64BE>;
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template class elf2::SharedFile<ELF32LE>;
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template class elf2::SharedFile<ELF32BE>;
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template class elf2::SharedFile<ELF64LE>;
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template class elf2::SharedFile<ELF64BE>;
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template std::unique_ptr<InputFile>
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elf2::createELFFile<ObjectFile>(MemoryBufferRef);
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template std::unique_ptr<InputFile>
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elf2::createELFFile<SharedFile>(MemoryBufferRef);
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