forked from OSchip/llvm-project
294 lines
9.8 KiB
C++
294 lines
9.8 KiB
C++
//===- InputSection.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 "InputSection.h"
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#include "Config.h"
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#include "Error.h"
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#include "InputFiles.h"
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#include "OutputSections.h"
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#include "Target.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 lld;
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using namespace lld::elf2;
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template <class ELFT>
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InputSectionBase<ELFT>::InputSectionBase(ObjectFile<ELFT> *File,
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const Elf_Shdr *Header,
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Kind SectionKind)
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: Header(Header), File(File), SectionKind(SectionKind) {}
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template <class ELFT> StringRef InputSectionBase<ELFT>::getSectionName() const {
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ErrorOr<StringRef> Name = File->getObj().getSectionName(this->Header);
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error(Name);
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return *Name;
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}
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template <class ELFT>
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ArrayRef<uint8_t> InputSectionBase<ELFT>::getSectionData() const {
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ErrorOr<ArrayRef<uint8_t>> Ret =
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this->File->getObj().getSectionContents(this->Header);
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error(Ret);
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return *Ret;
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}
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template <class ELFT>
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typename ELFFile<ELFT>::uintX_t
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InputSectionBase<ELFT>::getOffset(uintX_t Offset) {
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switch (SectionKind) {
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case Regular:
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return cast<InputSection<ELFT>>(this)->OutSecOff + Offset;
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case EHFrame:
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return cast<EHInputSection<ELFT>>(this)->getOffset(Offset);
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case Merge:
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return cast<MergeInputSection<ELFT>>(this)->getOffset(Offset);
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}
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llvm_unreachable("Invalid section kind");
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}
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template <class ELFT>
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typename ELFFile<ELFT>::uintX_t
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InputSectionBase<ELFT>::getOffset(const Elf_Sym &Sym) {
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return getOffset(Sym.st_value);
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}
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// Returns a section that Rel relocation is pointing to.
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template <class ELFT>
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InputSectionBase<ELFT> *
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InputSectionBase<ELFT>::getRelocTarget(const Elf_Rel &Rel) {
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// Global symbol
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uint32_t SymIndex = Rel.getSymbol(Config->Mips64EL);
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if (SymbolBody *B = File->getSymbolBody(SymIndex))
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if (auto *D = dyn_cast<DefinedRegular<ELFT>>(B->repl()))
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return &D->Section;
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// Local symbol
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if (const Elf_Sym *Sym = File->getLocalSymbol(SymIndex))
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if (InputSectionBase<ELFT> *Sec = File->getSection(*Sym))
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return Sec;
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return nullptr;
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}
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template <class ELFT>
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InputSectionBase<ELFT> *
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InputSectionBase<ELFT>::getRelocTarget(const Elf_Rela &Rel) {
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return getRelocTarget(reinterpret_cast<const Elf_Rel &>(Rel));
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}
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template <class ELFT>
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InputSection<ELFT>::InputSection(ObjectFile<ELFT> *F, const Elf_Shdr *Header)
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: InputSectionBase<ELFT>(F, Header, Base::Regular) {}
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template <class ELFT>
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bool InputSection<ELFT>::classof(const InputSectionBase<ELFT> *S) {
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return S->SectionKind == Base::Regular;
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}
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template <class ELFT>
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template <bool isRela>
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void InputSectionBase<ELFT>::relocate(
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uint8_t *Buf, uint8_t *BufEnd,
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iterator_range<const Elf_Rel_Impl<ELFT, isRela> *> Rels) {
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typedef Elf_Rel_Impl<ELFT, isRela> RelType;
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size_t Num = Rels.end() - Rels.begin();
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for (size_t I = 0; I < Num; ++I) {
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const RelType &RI = *(Rels.begin() + I);
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uint32_t SymIndex = RI.getSymbol(Config->Mips64EL);
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uint32_t Type = RI.getType(Config->Mips64EL);
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uintX_t Offset = getOffset(RI.r_offset);
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if (Offset == (uintX_t)-1)
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continue;
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uint8_t *BufLoc = Buf + Offset;
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uintX_t AddrLoc = OutSec->getVA() + Offset;
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if (Target->isTlsLocalDynamicReloc(Type) &&
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!Target->isTlsOptimized(Type, nullptr)) {
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Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc,
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Out<ELFT>::Got->getVA() +
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Out<ELFT>::LocalModuleTlsIndexOffset +
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getAddend<ELFT>(RI));
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continue;
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}
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// Handle relocations for local symbols -- they never get
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// resolved so we don't allocate a SymbolBody.
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const Elf_Shdr *SymTab = File->getSymbolTable();
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if (SymIndex < SymTab->sh_info) {
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uintX_t SymVA = getLocalRelTarget(*File, RI);
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Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc, SymVA);
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continue;
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}
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SymbolBody &Body = *File->getSymbolBody(SymIndex)->repl();
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if (Target->isTlsGlobalDynamicReloc(Type) &&
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!Target->isTlsOptimized(Type, &Body)) {
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Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc,
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Out<ELFT>::Got->getEntryAddr(Body) +
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getAddend<ELFT>(RI));
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continue;
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}
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if (Target->isTlsOptimized(Type, &Body)) {
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// By optimizing TLS relocations, it is sometimes needed to skip
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// relocations that immediately follow TLS relocations. This function
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// knows how many slots we need to skip.
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I += Target->relocateTlsOptimize(BufLoc, BufEnd, Type, AddrLoc,
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getSymVA<ELFT>(Body));
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continue;
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}
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uintX_t SymVA = getSymVA<ELFT>(Body);
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if (Target->relocNeedsPlt(Type, Body)) {
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SymVA = Out<ELFT>::Plt->getEntryAddr(Body);
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Type = Target->getPltRefReloc(Type);
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} else if (Target->relocNeedsGot(Type, Body)) {
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SymVA = Out<ELFT>::Got->getEntryAddr(Body);
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Type = Body.isTLS() ? Target->getTlsGotReloc()
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: Target->getGotRefReloc(Type);
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} else if (!Target->relocNeedsCopy(Type, Body) &&
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isa<SharedSymbol<ELFT>>(Body)) {
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continue;
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} else if (Target->isTlsDynReloc(Type)) {
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continue;
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}
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Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc,
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SymVA + getAddend<ELFT>(RI));
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}
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}
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template <class ELFT> void InputSection<ELFT>::writeTo(uint8_t *Buf) {
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if (this->Header->sh_type == SHT_NOBITS)
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return;
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// Copy section contents from source object file to output file.
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ArrayRef<uint8_t> Data = this->getSectionData();
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memcpy(Buf + OutSecOff, Data.data(), Data.size());
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ELFFile<ELFT> &EObj = this->File->getObj();
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uint8_t *BufEnd = Buf + OutSecOff + Data.size();
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// Iterate over all relocation sections that apply to this section.
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for (const Elf_Shdr *RelSec : this->RelocSections) {
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if (RelSec->sh_type == SHT_RELA)
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this->relocate(Buf, BufEnd, EObj.relas(RelSec));
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else
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this->relocate(Buf, BufEnd, EObj.rels(RelSec));
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}
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}
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template <class ELFT>
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SplitInputSection<ELFT>::SplitInputSection(
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ObjectFile<ELFT> *File, const Elf_Shdr *Header,
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typename InputSectionBase<ELFT>::Kind SectionKind)
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: InputSectionBase<ELFT>(File, Header, SectionKind) {}
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template <class ELFT>
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EHInputSection<ELFT>::EHInputSection(ObjectFile<ELFT> *F,
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const Elf_Shdr *Header)
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: SplitInputSection<ELFT>(F, Header, InputSectionBase<ELFT>::EHFrame) {}
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template <class ELFT>
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bool EHInputSection<ELFT>::classof(const InputSectionBase<ELFT> *S) {
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return S->SectionKind == InputSectionBase<ELFT>::EHFrame;
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}
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template <class ELFT>
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typename EHInputSection<ELFT>::uintX_t
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EHInputSection<ELFT>::getOffset(uintX_t Offset) {
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std::pair<uintX_t, uintX_t> *I = this->getRangeAndSize(Offset).first;
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uintX_t Base = I->second;
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if (Base == uintX_t(-1))
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return -1; // Not in the output
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uintX_t Addend = Offset - I->first;
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return Base + Addend;
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}
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template <class ELFT>
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MergeInputSection<ELFT>::MergeInputSection(ObjectFile<ELFT> *F,
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const Elf_Shdr *Header)
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: SplitInputSection<ELFT>(F, Header, InputSectionBase<ELFT>::Merge) {}
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template <class ELFT>
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bool MergeInputSection<ELFT>::classof(const InputSectionBase<ELFT> *S) {
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return S->SectionKind == InputSectionBase<ELFT>::Merge;
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}
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template <class ELFT>
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std::pair<std::pair<typename ELFFile<ELFT>::uintX_t,
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typename ELFFile<ELFT>::uintX_t> *,
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typename ELFFile<ELFT>::uintX_t>
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SplitInputSection<ELFT>::getRangeAndSize(uintX_t Offset) {
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ArrayRef<uint8_t> D = this->getSectionData();
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StringRef Data((const char *)D.data(), D.size());
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uintX_t Size = Data.size();
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if (Offset >= Size)
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error("Entry is past the end of the section");
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// Find the element this offset points to.
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auto I = std::upper_bound(
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Offsets.begin(), Offsets.end(), Offset,
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[](const uintX_t &A, const std::pair<uintX_t, uintX_t> &B) {
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return A < B.first;
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});
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uintX_t End = I == Offsets.end() ? Data.size() : I->first;
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--I;
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return std::make_pair(&*I, End);
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}
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template <class ELFT>
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typename MergeInputSection<ELFT>::uintX_t
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MergeInputSection<ELFT>::getOffset(uintX_t Offset) {
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std::pair<std::pair<uintX_t, uintX_t> *, uintX_t> T =
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this->getRangeAndSize(Offset);
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std::pair<uintX_t, uintX_t> *I = T.first;
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uintX_t End = T.second;
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uintX_t Start = I->first;
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// Compute the Addend and if the Base is cached, return.
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uintX_t Addend = Offset - Start;
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uintX_t &Base = I->second;
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if (Base != uintX_t(-1))
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return Base + Addend;
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// Map the base to the offset in the output section and cashe it.
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ArrayRef<uint8_t> D = this->getSectionData();
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StringRef Data((const char *)D.data(), D.size());
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StringRef Entry = Data.substr(Start, End - Start);
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Base =
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static_cast<MergeOutputSection<ELFT> *>(this->OutSec)->getOffset(Entry);
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return Base + Addend;
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}
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namespace lld {
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namespace elf2 {
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template class InputSectionBase<object::ELF32LE>;
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template class InputSectionBase<object::ELF32BE>;
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template class InputSectionBase<object::ELF64LE>;
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template class InputSectionBase<object::ELF64BE>;
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template class InputSection<object::ELF32LE>;
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template class InputSection<object::ELF32BE>;
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template class InputSection<object::ELF64LE>;
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template class InputSection<object::ELF64BE>;
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template class EHInputSection<object::ELF32LE>;
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template class EHInputSection<object::ELF32BE>;
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template class EHInputSection<object::ELF64LE>;
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template class EHInputSection<object::ELF64BE>;
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template class MergeInputSection<object::ELF32LE>;
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template class MergeInputSection<object::ELF32BE>;
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template class MergeInputSection<object::ELF64LE>;
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template class MergeInputSection<object::ELF64BE>;
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}
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}
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