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Diffstat (limited to 'ELF/InputSection.cpp')
| -rw-r--r-- | ELF/InputSection.cpp | 399 |
1 files changed, 399 insertions, 0 deletions
diff --git a/ELF/InputSection.cpp b/ELF/InputSection.cpp new file mode 100644 index 0000000000000..2548200feb65b --- /dev/null +++ b/ELF/InputSection.cpp @@ -0,0 +1,399 @@ +//===- InputSection.cpp ---------------------------------------------------===// +// +// The LLVM Linker +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include "InputSection.h" +#include "Config.h" +#include "Error.h" +#include "InputFiles.h" +#include "OutputSections.h" +#include "Target.h" + +using namespace llvm; +using namespace llvm::ELF; +using namespace llvm::object; + +using namespace lld; +using namespace lld::elf2; + +template <class ELFT> +InputSectionBase<ELFT>::InputSectionBase(ObjectFile<ELFT> *File, + const Elf_Shdr *Header, + Kind SectionKind) + : Header(Header), File(File), SectionKind(SectionKind) {} + +template <class ELFT> StringRef InputSectionBase<ELFT>::getSectionName() const { + ErrorOr<StringRef> Name = File->getObj().getSectionName(this->Header); + error(Name); + return *Name; +} + +template <class ELFT> +ArrayRef<uint8_t> InputSectionBase<ELFT>::getSectionData() const { + ErrorOr<ArrayRef<uint8_t>> Ret = + this->File->getObj().getSectionContents(this->Header); + error(Ret); + return *Ret; +} + +template <class ELFT> +typename ELFFile<ELFT>::uintX_t +InputSectionBase<ELFT>::getOffset(uintX_t Offset) { + switch (SectionKind) { + case Regular: + return cast<InputSection<ELFT>>(this)->OutSecOff + Offset; + case EHFrame: + return cast<EHInputSection<ELFT>>(this)->getOffset(Offset); + case Merge: + return cast<MergeInputSection<ELFT>>(this)->getOffset(Offset); + case MipsReginfo: + return cast<MipsReginfoInputSection<ELFT>>(this)->getOffset(Offset); + } + llvm_unreachable("Invalid section kind"); +} + +template <class ELFT> +typename ELFFile<ELFT>::uintX_t +InputSectionBase<ELFT>::getOffset(const Elf_Sym &Sym) { + return getOffset(Sym.st_value); +} + +// Returns a section that Rel relocation is pointing to. +template <class ELFT> +InputSectionBase<ELFT> * +InputSectionBase<ELFT>::getRelocTarget(const Elf_Rel &Rel) { + // Global symbol + uint32_t SymIndex = Rel.getSymbol(Config->Mips64EL); + if (SymbolBody *B = File->getSymbolBody(SymIndex)) + if (auto *D = dyn_cast<DefinedRegular<ELFT>>(B->repl())) + return D->Section; + // Local symbol + if (const Elf_Sym *Sym = File->getLocalSymbol(SymIndex)) + if (InputSectionBase<ELFT> *Sec = File->getSection(*Sym)) + return Sec; + return nullptr; +} + +template <class ELFT> +InputSectionBase<ELFT> * +InputSectionBase<ELFT>::getRelocTarget(const Elf_Rela &Rel) { + return getRelocTarget(reinterpret_cast<const Elf_Rel &>(Rel)); +} + +template <class ELFT> +InputSection<ELFT>::InputSection(ObjectFile<ELFT> *F, const Elf_Shdr *Header) + : InputSectionBase<ELFT>(F, Header, Base::Regular) {} + +template <class ELFT> +bool InputSection<ELFT>::classof(const InputSectionBase<ELFT> *S) { + return S->SectionKind == Base::Regular; +} + +template <class ELFT> +template <bool isRela> +uint8_t * +InputSectionBase<ELFT>::findMipsPairedReloc(uint8_t *Buf, uint32_t SymIndex, + uint32_t Type, + RelIteratorRange<isRela> Rels) { + // Some MIPS relocations use addend calculated from addend of the relocation + // itself and addend of paired relocation. ABI requires to compute such + // combined addend in case of REL relocation record format only. + // See p. 4-17 at ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf + if (isRela || Config->EMachine != EM_MIPS) + return nullptr; + if (Type == R_MIPS_HI16) + Type = R_MIPS_LO16; + else if (Type == R_MIPS_PCHI16) + Type = R_MIPS_PCLO16; + else if (Type == R_MICROMIPS_HI16) + Type = R_MICROMIPS_LO16; + else + return nullptr; + for (const auto &RI : Rels) { + if (RI.getType(Config->Mips64EL) != Type) + continue; + if (RI.getSymbol(Config->Mips64EL) != SymIndex) + continue; + uintX_t Offset = getOffset(RI.r_offset); + if (Offset == (uintX_t)-1) + return nullptr; + return Buf + Offset; + } + return nullptr; +} + +template <class ELFT> +static typename llvm::object::ELFFile<ELFT>::uintX_t +getSymSize(SymbolBody &Body) { + if (auto *SS = dyn_cast<DefinedElf<ELFT>>(&Body)) + return SS->Sym.st_size; + return 0; +} + +template <class ELFT> +template <bool isRela> +void InputSectionBase<ELFT>::relocate(uint8_t *Buf, uint8_t *BufEnd, + RelIteratorRange<isRela> Rels) { + typedef Elf_Rel_Impl<ELFT, isRela> RelType; + size_t Num = Rels.end() - Rels.begin(); + for (size_t I = 0; I < Num; ++I) { + const RelType &RI = *(Rels.begin() + I); + uint32_t SymIndex = RI.getSymbol(Config->Mips64EL); + uint32_t Type = RI.getType(Config->Mips64EL); + uintX_t Offset = getOffset(RI.r_offset); + if (Offset == (uintX_t)-1) + continue; + + uint8_t *BufLoc = Buf + Offset; + uintX_t AddrLoc = OutSec->getVA() + Offset; + auto NextRelocs = llvm::make_range(&RI, Rels.end()); + + if (Target->isTlsLocalDynamicReloc(Type) && + !Target->isTlsOptimized(Type, nullptr)) { + Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc, + Out<ELFT>::Got->getLocalTlsIndexVA() + + getAddend<ELFT>(RI)); + continue; + } + + const Elf_Shdr *SymTab = File->getSymbolTable(); + SymbolBody *Body = nullptr; + if (SymIndex >= SymTab->sh_info) + Body = File->getSymbolBody(SymIndex)->repl(); + + if (Target->isTlsOptimized(Type, Body)) { + uintX_t SymVA; + if (!Body) + SymVA = getLocalRelTarget(*File, RI, 0); + else if (Target->relocNeedsGot(Type, *Body)) + SymVA = Out<ELFT>::Got->getEntryAddr(*Body); + else + SymVA = getSymVA<ELFT>(*Body); + // By optimizing TLS relocations, it is sometimes needed to skip + // relocations that immediately follow TLS relocations. This function + // knows how many slots we need to skip. + I += Target->relocateTlsOptimize(BufLoc, BufEnd, Type, AddrLoc, SymVA, + *Body); + continue; + } + + // Handle relocations for local symbols -- they never get + // resolved so we don't allocate a SymbolBody. + uintX_t A = getAddend<ELFT>(RI); + if (!Body) { + uintX_t SymVA = getLocalRelTarget(*File, RI, A); + // We need to adjust SymVA value in case of R_MIPS_GPREL16/32 relocations + // because they use the following expression to calculate the relocation's + // result for local symbol: S + A + GP0 - G. + if (Config->EMachine == EM_MIPS && + (Type == R_MIPS_GPREL16 || Type == R_MIPS_GPREL32)) + SymVA += File->getMipsGp0(); + Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc, SymVA, 0, + findMipsPairedReloc(Buf, SymIndex, Type, NextRelocs)); + continue; + } + + if (Target->isTlsGlobalDynamicReloc(Type) && + !Target->isTlsOptimized(Type, Body)) { + Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc, + Out<ELFT>::Got->getGlobalDynAddr(*Body) + + getAddend<ELFT>(RI)); + continue; + } + + uintX_t SymVA = getSymVA<ELFT>(*Body); + if (Target->relocNeedsPlt(Type, *Body)) { + SymVA = Out<ELFT>::Plt->getEntryAddr(*Body); + Type = Target->getPltRefReloc(Type); + } else if (Target->relocNeedsGot(Type, *Body)) { + SymVA = Out<ELFT>::Got->getEntryAddr(*Body); + if (Body->isTls()) + Type = Target->getTlsGotReloc(Type); + } else if (!Target->needsCopyRel(Type, *Body) && + isa<SharedSymbol<ELFT>>(*Body)) { + continue; + } else if (Target->isTlsDynReloc(Type, *Body) || + Target->isSizeDynReloc(Type, *Body)) { + continue; + } else if (Config->EMachine == EM_MIPS) { + if (Type == R_MIPS_HI16 && Body == Config->MipsGpDisp) + SymVA = getMipsGpAddr<ELFT>() - AddrLoc; + else if (Type == R_MIPS_LO16 && Body == Config->MipsGpDisp) + SymVA = getMipsGpAddr<ELFT>() - AddrLoc + 4; + } + uintX_t Size = getSymSize<ELFT>(*Body); + Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc, SymVA + A, Size + A, + findMipsPairedReloc(Buf, SymIndex, Type, NextRelocs)); + } +} + +template <class ELFT> void InputSection<ELFT>::writeTo(uint8_t *Buf) { + if (this->Header->sh_type == SHT_NOBITS) + return; + // Copy section contents from source object file to output file. + ArrayRef<uint8_t> Data = this->getSectionData(); + memcpy(Buf + OutSecOff, Data.data(), Data.size()); + + ELFFile<ELFT> &EObj = this->File->getObj(); + uint8_t *BufEnd = Buf + OutSecOff + Data.size(); + // Iterate over all relocation sections that apply to this section. + for (const Elf_Shdr *RelSec : this->RelocSections) { + if (RelSec->sh_type == SHT_RELA) + this->relocate(Buf, BufEnd, EObj.relas(RelSec)); + else + this->relocate(Buf, BufEnd, EObj.rels(RelSec)); + } +} + +template <class ELFT> +SplitInputSection<ELFT>::SplitInputSection( + ObjectFile<ELFT> *File, const Elf_Shdr *Header, + typename InputSectionBase<ELFT>::Kind SectionKind) + : InputSectionBase<ELFT>(File, Header, SectionKind) {} + +template <class ELFT> +EHInputSection<ELFT>::EHInputSection(ObjectFile<ELFT> *F, + const Elf_Shdr *Header) + : SplitInputSection<ELFT>(F, Header, InputSectionBase<ELFT>::EHFrame) { + // Mark .eh_frame sections as live by default because there are + // usually no relocations that point to .eh_frames. Otherwise, + // the garbage collector would drop all .eh_frame sections. + this->Live = true; +} + +template <class ELFT> +bool EHInputSection<ELFT>::classof(const InputSectionBase<ELFT> *S) { + return S->SectionKind == InputSectionBase<ELFT>::EHFrame; +} + +template <class ELFT> +typename EHInputSection<ELFT>::uintX_t +EHInputSection<ELFT>::getOffset(uintX_t Offset) { + // The file crtbeginT.o has relocations pointing to the start of an empty + // .eh_frame that is known to be the first in the link. It does that to + // identify the start of the output .eh_frame. Handle this special case. + if (this->getSectionHdr()->sh_size == 0) + return Offset; + std::pair<uintX_t, uintX_t> *I = this->getRangeAndSize(Offset).first; + uintX_t Base = I->second; + if (Base == uintX_t(-1)) + return -1; // Not in the output + + uintX_t Addend = Offset - I->first; + return Base + Addend; +} + +template <class ELFT> +MergeInputSection<ELFT>::MergeInputSection(ObjectFile<ELFT> *F, + const Elf_Shdr *Header) + : SplitInputSection<ELFT>(F, Header, InputSectionBase<ELFT>::Merge) {} + +template <class ELFT> +bool MergeInputSection<ELFT>::classof(const InputSectionBase<ELFT> *S) { + return S->SectionKind == InputSectionBase<ELFT>::Merge; +} + +template <class ELFT> +std::pair<std::pair<typename ELFFile<ELFT>::uintX_t, + typename ELFFile<ELFT>::uintX_t> *, + typename ELFFile<ELFT>::uintX_t> +SplitInputSection<ELFT>::getRangeAndSize(uintX_t Offset) { + ArrayRef<uint8_t> D = this->getSectionData(); + StringRef Data((const char *)D.data(), D.size()); + uintX_t Size = Data.size(); + if (Offset >= Size) + error("Entry is past the end of the section"); + + // Find the element this offset points to. + auto I = std::upper_bound( + Offsets.begin(), Offsets.end(), Offset, + [](const uintX_t &A, const std::pair<uintX_t, uintX_t> &B) { + return A < B.first; + }); + uintX_t End = I == Offsets.end() ? Data.size() : I->first; + --I; + return std::make_pair(&*I, End); +} + +template <class ELFT> +typename MergeInputSection<ELFT>::uintX_t +MergeInputSection<ELFT>::getOffset(uintX_t Offset) { + std::pair<std::pair<uintX_t, uintX_t> *, uintX_t> T = + this->getRangeAndSize(Offset); + std::pair<uintX_t, uintX_t> *I = T.first; + uintX_t End = T.second; + uintX_t Start = I->first; + + // Compute the Addend and if the Base is cached, return. + uintX_t Addend = Offset - Start; + uintX_t &Base = I->second; + if (Base != uintX_t(-1)) + return Base + Addend; + + // Map the base to the offset in the output section and cache it. + ArrayRef<uint8_t> D = this->getSectionData(); + StringRef Data((const char *)D.data(), D.size()); + StringRef Entry = Data.substr(Start, End - Start); + Base = + static_cast<MergeOutputSection<ELFT> *>(this->OutSec)->getOffset(Entry); + return Base + Addend; +} + +template <class ELFT> +MipsReginfoInputSection<ELFT>::MipsReginfoInputSection(ObjectFile<ELFT> *F, + const Elf_Shdr *Header) + : InputSectionBase<ELFT>(F, Header, InputSectionBase<ELFT>::MipsReginfo) {} + +template <class ELFT> +uint32_t MipsReginfoInputSection<ELFT>::getGeneralMask() const { + ArrayRef<uint8_t> D = this->getSectionData(); + if (D.size() != sizeof(Elf_Mips_RegInfo)) + error("Invalid size of .reginfo section"); + return reinterpret_cast<const Elf_Mips_RegInfo *>(D.data())->ri_gprmask; +} + +template <class ELFT> uint32_t MipsReginfoInputSection<ELFT>::getGp0() const { + ArrayRef<uint8_t> D = this->getSectionData(); + if (D.size() != sizeof(Elf_Mips_RegInfo)) + error("Invalid size of .reginfo section"); + return reinterpret_cast<const Elf_Mips_RegInfo *>(D.data())->ri_gp_value; +} + +template <class ELFT> +bool MipsReginfoInputSection<ELFT>::classof(const InputSectionBase<ELFT> *S) { + return S->SectionKind == InputSectionBase<ELFT>::MipsReginfo; +} + +namespace lld { +namespace elf2 { +template class InputSectionBase<object::ELF32LE>; +template class InputSectionBase<object::ELF32BE>; +template class InputSectionBase<object::ELF64LE>; +template class InputSectionBase<object::ELF64BE>; + +template class InputSection<object::ELF32LE>; +template class InputSection<object::ELF32BE>; +template class InputSection<object::ELF64LE>; +template class InputSection<object::ELF64BE>; + +template class EHInputSection<object::ELF32LE>; +template class EHInputSection<object::ELF32BE>; +template class EHInputSection<object::ELF64LE>; +template class EHInputSection<object::ELF64BE>; + +template class MergeInputSection<object::ELF32LE>; +template class MergeInputSection<object::ELF32BE>; +template class MergeInputSection<object::ELF64LE>; +template class MergeInputSection<object::ELF64BE>; + +template class MipsReginfoInputSection<object::ELF32LE>; +template class MipsReginfoInputSection<object::ELF32BE>; +template class MipsReginfoInputSection<object::ELF64LE>; +template class MipsReginfoInputSection<object::ELF64BE>; +} +} |