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Diffstat (limited to 'contrib/llvm/lib/MC/ELFObjectWriter.cpp')
| -rw-r--r-- | contrib/llvm/lib/MC/ELFObjectWriter.cpp | 1594 |
1 files changed, 1594 insertions, 0 deletions
diff --git a/contrib/llvm/lib/MC/ELFObjectWriter.cpp b/contrib/llvm/lib/MC/ELFObjectWriter.cpp new file mode 100644 index 0000000..3d99548 --- /dev/null +++ b/contrib/llvm/lib/MC/ELFObjectWriter.cpp @@ -0,0 +1,1594 @@ +//===- lib/MC/ELFObjectWriter.cpp - ELF File Writer -----------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements ELF object file writer information. +// +//===----------------------------------------------------------------------===// + +#include "llvm/MC/MCELFObjectWriter.h" +#include "llvm/ADT/OwningPtr.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/SmallString.h" +#include "llvm/ADT/StringMap.h" +#include "llvm/MC/MCAsmBackend.h" +#include "llvm/MC/MCAsmLayout.h" +#include "llvm/MC/MCAssembler.h" +#include "llvm/MC/MCContext.h" +#include "llvm/MC/MCELF.h" +#include "llvm/MC/MCELFSymbolFlags.h" +#include "llvm/MC/MCExpr.h" +#include "llvm/MC/MCFixupKindInfo.h" +#include "llvm/MC/MCObjectWriter.h" +#include "llvm/MC/MCSectionELF.h" +#include "llvm/MC/MCValue.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/ELF.h" +#include "llvm/Support/ErrorHandling.h" +#include <vector> +using namespace llvm; + +#undef DEBUG_TYPE +#define DEBUG_TYPE "reloc-info" + +namespace { +class ELFObjectWriter : public MCObjectWriter { + protected: + + static bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind); + static bool RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant); + static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout); + static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data, + bool Used, bool Renamed); + static bool isLocal(const MCSymbolData &Data, bool isSignature, + bool isUsedInReloc); + static bool IsELFMetaDataSection(const MCSectionData &SD); + static uint64_t DataSectionSize(const MCSectionData &SD); + static uint64_t GetSectionFileSize(const MCAsmLayout &Layout, + const MCSectionData &SD); + static uint64_t GetSectionAddressSize(const MCAsmLayout &Layout, + const MCSectionData &SD); + + void WriteDataSectionData(MCAssembler &Asm, + const MCAsmLayout &Layout, + const MCSectionELF &Section); + + /*static bool isFixupKindX86RIPRel(unsigned Kind) { + return Kind == X86::reloc_riprel_4byte || + Kind == X86::reloc_riprel_4byte_movq_load; + }*/ + + /// ELFSymbolData - Helper struct for containing some precomputed + /// information on symbols. + struct ELFSymbolData { + MCSymbolData *SymbolData; + uint64_t StringIndex; + uint32_t SectionIndex; + + // Support lexicographic sorting. + bool operator<(const ELFSymbolData &RHS) const { + if (MCELF::GetType(*SymbolData) == ELF::STT_FILE) + return true; + if (MCELF::GetType(*RHS.SymbolData) == ELF::STT_FILE) + return false; + return SymbolData->getSymbol().getName() < + RHS.SymbolData->getSymbol().getName(); + } + }; + + /// The target specific ELF writer instance. + llvm::OwningPtr<MCELFObjectTargetWriter> TargetObjectWriter; + + SmallPtrSet<const MCSymbol *, 16> UsedInReloc; + SmallPtrSet<const MCSymbol *, 16> WeakrefUsedInReloc; + DenseMap<const MCSymbol *, const MCSymbol *> Renames; + + llvm::DenseMap<const MCSectionData*, + std::vector<ELFRelocationEntry> > Relocations; + DenseMap<const MCSection*, uint64_t> SectionStringTableIndex; + + /// @} + /// @name Symbol Table Data + /// @{ + + SmallString<256> StringTable; + std::vector<ELFSymbolData> LocalSymbolData; + std::vector<ELFSymbolData> ExternalSymbolData; + std::vector<ELFSymbolData> UndefinedSymbolData; + + /// @} + + bool NeedsGOT; + + bool NeedsSymtabShndx; + + // This holds the symbol table index of the last local symbol. + unsigned LastLocalSymbolIndex; + // This holds the .strtab section index. + unsigned StringTableIndex; + // This holds the .symtab section index. + unsigned SymbolTableIndex; + + unsigned ShstrtabIndex; + + + const MCSymbol *SymbolToReloc(const MCAssembler &Asm, + const MCValue &Target, + const MCFragment &F, + const MCFixup &Fixup, + bool IsPCRel) const; + + // TargetObjectWriter wrappers. + const MCSymbol *ExplicitRelSym(const MCAssembler &Asm, + const MCValue &Target, + const MCFragment &F, + const MCFixup &Fixup, + bool IsPCRel) const { + return TargetObjectWriter->ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel); + } + const MCSymbol *undefinedExplicitRelSym(const MCValue &Target, + const MCFixup &Fixup, + bool IsPCRel) const { + return TargetObjectWriter->undefinedExplicitRelSym(Target, Fixup, + IsPCRel); + } + + bool is64Bit() const { return TargetObjectWriter->is64Bit(); } + bool hasRelocationAddend() const { + return TargetObjectWriter->hasRelocationAddend(); + } + unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup, + bool IsPCRel, bool IsRelocWithSymbol, + int64_t Addend) const { + return TargetObjectWriter->GetRelocType(Target, Fixup, IsPCRel, + IsRelocWithSymbol, Addend); + } + + public: + ELFObjectWriter(MCELFObjectTargetWriter *MOTW, + raw_ostream &_OS, bool IsLittleEndian) + : MCObjectWriter(_OS, IsLittleEndian), + TargetObjectWriter(MOTW), + NeedsGOT(false), NeedsSymtabShndx(false) { + } + + virtual ~ELFObjectWriter(); + + void WriteWord(uint64_t W) { + if (is64Bit()) + Write64(W); + else + Write32(W); + } + + void StringLE16(char *buf, uint16_t Value) { + buf[0] = char(Value >> 0); + buf[1] = char(Value >> 8); + } + + void StringLE32(char *buf, uint32_t Value) { + StringLE16(buf, uint16_t(Value >> 0)); + StringLE16(buf + 2, uint16_t(Value >> 16)); + } + + void StringLE64(char *buf, uint64_t Value) { + StringLE32(buf, uint32_t(Value >> 0)); + StringLE32(buf + 4, uint32_t(Value >> 32)); + } + + void StringBE16(char *buf ,uint16_t Value) { + buf[0] = char(Value >> 8); + buf[1] = char(Value >> 0); + } + + void StringBE32(char *buf, uint32_t Value) { + StringBE16(buf, uint16_t(Value >> 16)); + StringBE16(buf + 2, uint16_t(Value >> 0)); + } + + void StringBE64(char *buf, uint64_t Value) { + StringBE32(buf, uint32_t(Value >> 32)); + StringBE32(buf + 4, uint32_t(Value >> 0)); + } + + void String8(MCDataFragment &F, uint8_t Value) { + char buf[1]; + buf[0] = Value; + F.getContents().append(&buf[0], &buf[1]); + } + + void String16(MCDataFragment &F, uint16_t Value) { + char buf[2]; + if (isLittleEndian()) + StringLE16(buf, Value); + else + StringBE16(buf, Value); + F.getContents().append(&buf[0], &buf[2]); + } + + void String32(MCDataFragment &F, uint32_t Value) { + char buf[4]; + if (isLittleEndian()) + StringLE32(buf, Value); + else + StringBE32(buf, Value); + F.getContents().append(&buf[0], &buf[4]); + } + + void String64(MCDataFragment &F, uint64_t Value) { + char buf[8]; + if (isLittleEndian()) + StringLE64(buf, Value); + else + StringBE64(buf, Value); + F.getContents().append(&buf[0], &buf[8]); + } + + void WriteHeader(const MCAssembler &Asm, + uint64_t SectionDataSize, + unsigned NumberOfSections); + + void WriteSymbolEntry(MCDataFragment *SymtabF, + MCDataFragment *ShndxF, + uint64_t name, uint8_t info, + uint64_t value, uint64_t size, + uint8_t other, uint32_t shndx, + bool Reserved); + + void WriteSymbol(MCDataFragment *SymtabF, MCDataFragment *ShndxF, + ELFSymbolData &MSD, + const MCAsmLayout &Layout); + + typedef DenseMap<const MCSectionELF*, uint32_t> SectionIndexMapTy; + void WriteSymbolTable(MCDataFragment *SymtabF, + MCDataFragment *ShndxF, + const MCAssembler &Asm, + const MCAsmLayout &Layout, + const SectionIndexMapTy &SectionIndexMap); + + virtual void RecordRelocation(const MCAssembler &Asm, + const MCAsmLayout &Layout, + const MCFragment *Fragment, + const MCFixup &Fixup, + MCValue Target, uint64_t &FixedValue); + + uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm, + const MCSymbol *S); + + // Map from a group section to the signature symbol + typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy; + // Map from a signature symbol to the group section + typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy; + // Map from a section to the section with the relocations + typedef DenseMap<const MCSectionELF*, const MCSectionELF*> RelMapTy; + // Map from a section to its offset + typedef DenseMap<const MCSectionELF*, uint64_t> SectionOffsetMapTy; + + /// ComputeSymbolTable - Compute the symbol table data + /// + /// \param Asm - The assembler. + /// \param SectionIndexMap - Maps a section to its index. + /// \param RevGroupMap - Maps a signature symbol to the group section. + /// \param NumRegularSections - Number of non-relocation sections. + void ComputeSymbolTable(MCAssembler &Asm, + const SectionIndexMapTy &SectionIndexMap, + RevGroupMapTy RevGroupMap, + unsigned NumRegularSections); + + void ComputeIndexMap(MCAssembler &Asm, + SectionIndexMapTy &SectionIndexMap, + const RelMapTy &RelMap); + + void CreateRelocationSections(MCAssembler &Asm, MCAsmLayout &Layout, + RelMapTy &RelMap); + + void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout, + const RelMapTy &RelMap); + + void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout, + SectionIndexMapTy &SectionIndexMap, + const RelMapTy &RelMap); + + // Create the sections that show up in the symbol table. Currently + // those are the .note.GNU-stack section and the group sections. + void CreateIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout, + GroupMapTy &GroupMap, + RevGroupMapTy &RevGroupMap, + SectionIndexMapTy &SectionIndexMap, + const RelMapTy &RelMap); + + virtual void ExecutePostLayoutBinding(MCAssembler &Asm, + const MCAsmLayout &Layout); + + void WriteSectionHeader(MCAssembler &Asm, const GroupMapTy &GroupMap, + const MCAsmLayout &Layout, + const SectionIndexMapTy &SectionIndexMap, + const SectionOffsetMapTy &SectionOffsetMap); + + void ComputeSectionOrder(MCAssembler &Asm, + std::vector<const MCSectionELF*> &Sections); + + void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags, + uint64_t Address, uint64_t Offset, + uint64_t Size, uint32_t Link, uint32_t Info, + uint64_t Alignment, uint64_t EntrySize); + + void WriteRelocationsFragment(const MCAssembler &Asm, + MCDataFragment *F, + const MCSectionData *SD); + + virtual bool + IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, + const MCSymbolData &DataA, + const MCFragment &FB, + bool InSet, + bool IsPCRel) const; + + virtual void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout); + void WriteSection(MCAssembler &Asm, + const SectionIndexMapTy &SectionIndexMap, + uint32_t GroupSymbolIndex, + uint64_t Offset, uint64_t Size, uint64_t Alignment, + const MCSectionELF &Section); + }; +} + +bool ELFObjectWriter::isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) { + const MCFixupKindInfo &FKI = + Asm.getBackend().getFixupKindInfo((MCFixupKind) Kind); + + return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel; +} + +bool ELFObjectWriter::RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant) { + switch (Variant) { + default: + return false; + case MCSymbolRefExpr::VK_GOT: + case MCSymbolRefExpr::VK_PLT: + case MCSymbolRefExpr::VK_GOTPCREL: + case MCSymbolRefExpr::VK_GOTOFF: + case MCSymbolRefExpr::VK_TPOFF: + case MCSymbolRefExpr::VK_TLSGD: + case MCSymbolRefExpr::VK_GOTTPOFF: + case MCSymbolRefExpr::VK_INDNTPOFF: + case MCSymbolRefExpr::VK_NTPOFF: + case MCSymbolRefExpr::VK_GOTNTPOFF: + case MCSymbolRefExpr::VK_TLSLDM: + case MCSymbolRefExpr::VK_DTPOFF: + case MCSymbolRefExpr::VK_TLSLD: + return true; + } +} + +ELFObjectWriter::~ELFObjectWriter() +{} + +// Emit the ELF header. +void ELFObjectWriter::WriteHeader(const MCAssembler &Asm, + uint64_t SectionDataSize, + unsigned NumberOfSections) { + // ELF Header + // ---------- + // + // Note + // ---- + // emitWord method behaves differently for ELF32 and ELF64, writing + // 4 bytes in the former and 8 in the latter. + + Write8(0x7f); // e_ident[EI_MAG0] + Write8('E'); // e_ident[EI_MAG1] + Write8('L'); // e_ident[EI_MAG2] + Write8('F'); // e_ident[EI_MAG3] + + Write8(is64Bit() ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS] + + // e_ident[EI_DATA] + Write8(isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB); + + Write8(ELF::EV_CURRENT); // e_ident[EI_VERSION] + // e_ident[EI_OSABI] + Write8(TargetObjectWriter->getOSABI()); + Write8(0); // e_ident[EI_ABIVERSION] + + WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD); + + Write16(ELF::ET_REL); // e_type + + Write16(TargetObjectWriter->getEMachine()); // e_machine = target + + Write32(ELF::EV_CURRENT); // e_version + WriteWord(0); // e_entry, no entry point in .o file + WriteWord(0); // e_phoff, no program header for .o + WriteWord(SectionDataSize + (is64Bit() ? sizeof(ELF::Elf64_Ehdr) : + sizeof(ELF::Elf32_Ehdr))); // e_shoff = sec hdr table off in bytes + + // e_flags = whatever the target wants + Write32(Asm.getELFHeaderEFlags()); + + // e_ehsize = ELF header size + Write16(is64Bit() ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr)); + + Write16(0); // e_phentsize = prog header entry size + Write16(0); // e_phnum = # prog header entries = 0 + + // e_shentsize = Section header entry size + Write16(is64Bit() ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr)); + + // e_shnum = # of section header ents + if (NumberOfSections >= ELF::SHN_LORESERVE) + Write16(ELF::SHN_UNDEF); + else + Write16(NumberOfSections); + + // e_shstrndx = Section # of '.shstrtab' + if (ShstrtabIndex >= ELF::SHN_LORESERVE) + Write16(ELF::SHN_XINDEX); + else + Write16(ShstrtabIndex); +} + +void ELFObjectWriter::WriteSymbolEntry(MCDataFragment *SymtabF, + MCDataFragment *ShndxF, + uint64_t name, + uint8_t info, uint64_t value, + uint64_t size, uint8_t other, + uint32_t shndx, + bool Reserved) { + if (ShndxF) { + if (shndx >= ELF::SHN_LORESERVE && !Reserved) + String32(*ShndxF, shndx); + else + String32(*ShndxF, 0); + } + + uint16_t Index = (shndx >= ELF::SHN_LORESERVE && !Reserved) ? + uint16_t(ELF::SHN_XINDEX) : shndx; + + if (is64Bit()) { + String32(*SymtabF, name); // st_name + String8(*SymtabF, info); // st_info + String8(*SymtabF, other); // st_other + String16(*SymtabF, Index); // st_shndx + String64(*SymtabF, value); // st_value + String64(*SymtabF, size); // st_size + } else { + String32(*SymtabF, name); // st_name + String32(*SymtabF, value); // st_value + String32(*SymtabF, size); // st_size + String8(*SymtabF, info); // st_info + String8(*SymtabF, other); // st_other + String16(*SymtabF, Index); // st_shndx + } +} + +uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &Data, + const MCAsmLayout &Layout) { + if (Data.isCommon() && Data.isExternal()) + return Data.getCommonAlignment(); + + const MCSymbol &Symbol = Data.getSymbol(); + + if (Symbol.isAbsolute() && Symbol.isVariable()) { + if (const MCExpr *Value = Symbol.getVariableValue()) { + int64_t IntValue; + if (Value->EvaluateAsAbsolute(IntValue, Layout)) + return (uint64_t)IntValue; + } + } + + if (!Symbol.isInSection()) + return 0; + + + if (Data.getFragment()) { + if (Data.getFlags() & ELF_Other_ThumbFunc) + return Layout.getSymbolOffset(&Data)+1; + else + return Layout.getSymbolOffset(&Data); + } + + return 0; +} + +void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm, + const MCAsmLayout &Layout) { + // The presence of symbol versions causes undefined symbols and + // versions declared with @@@ to be renamed. + + for (MCAssembler::symbol_iterator it = Asm.symbol_begin(), + ie = Asm.symbol_end(); it != ie; ++it) { + const MCSymbol &Alias = it->getSymbol(); + const MCSymbol &Symbol = Alias.AliasedSymbol(); + MCSymbolData &SD = Asm.getSymbolData(Symbol); + + // Not an alias. + if (&Symbol == &Alias) + continue; + + StringRef AliasName = Alias.getName(); + size_t Pos = AliasName.find('@'); + if (Pos == StringRef::npos) + continue; + + // Aliases defined with .symvar copy the binding from the symbol they alias. + // This is the first place we are able to copy this information. + it->setExternal(SD.isExternal()); + MCELF::SetBinding(*it, MCELF::GetBinding(SD)); + + StringRef Rest = AliasName.substr(Pos); + if (!Symbol.isUndefined() && !Rest.startswith("@@@")) + continue; + + // FIXME: produce a better error message. + if (Symbol.isUndefined() && Rest.startswith("@@") && + !Rest.startswith("@@@")) + report_fatal_error("A @@ version cannot be undefined"); + + Renames.insert(std::make_pair(&Symbol, &Alias)); + } +} + +void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF, + MCDataFragment *ShndxF, + ELFSymbolData &MSD, + const MCAsmLayout &Layout) { + MCSymbolData &OrigData = *MSD.SymbolData; + MCSymbolData &Data = + Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol()); + + bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() || + Data.getSymbol().isVariable(); + + // Binding and Type share the same byte as upper and lower nibbles + uint8_t Binding = MCELF::GetBinding(OrigData); + uint8_t Type = MCELF::GetType(Data); + uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift); + + // Other and Visibility share the same byte with Visability using the lower + // 2 bits + uint8_t Visibility = MCELF::GetVisibility(OrigData); + uint8_t Other = MCELF::getOther(OrigData) << + (ELF_Other_Shift - ELF_STV_Shift); + Other |= Visibility; + + uint64_t Value = SymbolValue(Data, Layout); + uint64_t Size = 0; + + assert(!(Data.isCommon() && !Data.isExternal())); + + const MCExpr *ESize = Data.getSize(); + if (ESize) { + int64_t Res; + if (!ESize->EvaluateAsAbsolute(Res, Layout)) + report_fatal_error("Size expression must be absolute."); + Size = Res; + } + + // Write out the symbol table entry + WriteSymbolEntry(SymtabF, ShndxF, MSD.StringIndex, Info, Value, + Size, Other, MSD.SectionIndex, IsReserved); +} + +void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF, + MCDataFragment *ShndxF, + const MCAssembler &Asm, + const MCAsmLayout &Layout, + const SectionIndexMapTy &SectionIndexMap) { + // The string table must be emitted first because we need the index + // into the string table for all the symbol names. + assert(StringTable.size() && "Missing string table"); + + // FIXME: Make sure the start of the symbol table is aligned. + + // The first entry is the undefined symbol entry. + WriteSymbolEntry(SymtabF, ShndxF, 0, 0, 0, 0, 0, 0, false); + + // Write the symbol table entries. + LastLocalSymbolIndex = LocalSymbolData.size() + 1; + for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) { + ELFSymbolData &MSD = LocalSymbolData[i]; + WriteSymbol(SymtabF, ShndxF, MSD, Layout); + } + + // Write out a symbol table entry for each regular section. + for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; + ++i) { + const MCSectionELF &Section = + static_cast<const MCSectionELF&>(i->getSection()); + if (Section.getType() == ELF::SHT_RELA || + Section.getType() == ELF::SHT_REL || + Section.getType() == ELF::SHT_STRTAB || + Section.getType() == ELF::SHT_SYMTAB || + Section.getType() == ELF::SHT_SYMTAB_SHNDX) + continue; + WriteSymbolEntry(SymtabF, ShndxF, 0, ELF::STT_SECTION, 0, 0, + ELF::STV_DEFAULT, SectionIndexMap.lookup(&Section), + false); + LastLocalSymbolIndex++; + } + + for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) { + ELFSymbolData &MSD = ExternalSymbolData[i]; + MCSymbolData &Data = *MSD.SymbolData; + assert(((Data.getFlags() & ELF_STB_Global) || + (Data.getFlags() & ELF_STB_Weak)) && + "External symbol requires STB_GLOBAL or STB_WEAK flag"); + WriteSymbol(SymtabF, ShndxF, MSD, Layout); + if (MCELF::GetBinding(Data) == ELF::STB_LOCAL) + LastLocalSymbolIndex++; + } + + for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) { + ELFSymbolData &MSD = UndefinedSymbolData[i]; + MCSymbolData &Data = *MSD.SymbolData; + WriteSymbol(SymtabF, ShndxF, MSD, Layout); + if (MCELF::GetBinding(Data) == ELF::STB_LOCAL) + LastLocalSymbolIndex++; + } +} + +const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm, + const MCValue &Target, + const MCFragment &F, + const MCFixup &Fixup, + bool IsPCRel) const { + const MCSymbol &Symbol = Target.getSymA()->getSymbol(); + const MCSymbol &ASymbol = Symbol.AliasedSymbol(); + const MCSymbol *Renamed = Renames.lookup(&Symbol); + const MCSymbolData &SD = Asm.getSymbolData(Symbol); + + if (ASymbol.isUndefined()) { + if (Renamed) + return Renamed; + return undefinedExplicitRelSym(Target, Fixup, IsPCRel); + } + + if (SD.isExternal()) { + if (Renamed) + return Renamed; + return &Symbol; + } + + const MCSectionELF &Section = + static_cast<const MCSectionELF&>(ASymbol.getSection()); + const SectionKind secKind = Section.getKind(); + + if (secKind.isBSS()) + return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel); + + if (secKind.isThreadLocal()) { + if (Renamed) + return Renamed; + return &Symbol; + } + + MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind(); + const MCSectionELF &Sec2 = + static_cast<const MCSectionELF&>(F.getParent()->getSection()); + + if (&Sec2 != &Section && + (Kind == MCSymbolRefExpr::VK_PLT || + Kind == MCSymbolRefExpr::VK_GOTPCREL || + Kind == MCSymbolRefExpr::VK_GOTOFF)) { + if (Renamed) + return Renamed; + return &Symbol; + } + + if (Section.getFlags() & ELF::SHF_MERGE) { + if (Target.getConstant() == 0) + return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel); + if (Renamed) + return Renamed; + return &Symbol; + } + + return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel); + +} + + +void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm, + const MCAsmLayout &Layout, + const MCFragment *Fragment, + const MCFixup &Fixup, + MCValue Target, + uint64_t &FixedValue) { + int64_t Addend = 0; + int Index = 0; + int64_t Value = Target.getConstant(); + const MCSymbol *RelocSymbol = NULL; + + bool IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind()); + if (!Target.isAbsolute()) { + const MCSymbol &Symbol = Target.getSymA()->getSymbol(); + const MCSymbol &ASymbol = Symbol.AliasedSymbol(); + RelocSymbol = SymbolToReloc(Asm, Target, *Fragment, Fixup, IsPCRel); + + if (const MCSymbolRefExpr *RefB = Target.getSymB()) { + const MCSymbol &SymbolB = RefB->getSymbol(); + MCSymbolData &SDB = Asm.getSymbolData(SymbolB); + IsPCRel = true; + + // Offset of the symbol in the section + int64_t a = Layout.getSymbolOffset(&SDB); + + // Offset of the relocation in the section + int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset(); + Value += b - a; + } + + if (!RelocSymbol) { + MCSymbolData &SD = Asm.getSymbolData(ASymbol); + MCFragment *F = SD.getFragment(); + + if (F) { + Index = F->getParent()->getOrdinal() + 1; + // Offset of the symbol in the section + Value += Layout.getSymbolOffset(&SD); + } else { + Index = 0; + } + } else { + if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref) + WeakrefUsedInReloc.insert(RelocSymbol); + else + UsedInReloc.insert(RelocSymbol); + Index = -1; + } + Addend = Value; + if (hasRelocationAddend()) + Value = 0; + } + + FixedValue = Value; + unsigned Type = GetRelocType(Target, Fixup, IsPCRel, + (RelocSymbol != 0), Addend); + MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ? + MCSymbolRefExpr::VK_None : Target.getSymA()->getKind(); + if (RelocNeedsGOT(Modifier)) + NeedsGOT = true; + + uint64_t RelocOffset = Layout.getFragmentOffset(Fragment) + + Fixup.getOffset(); + + // FIXME: no tests cover this. Is adjustFixupOffset dead code? + TargetObjectWriter->adjustFixupOffset(Fixup, RelocOffset); + + if (!hasRelocationAddend()) + Addend = 0; + + if (is64Bit()) + assert(isInt<64>(Addend)); + else + assert(isInt<32>(Addend)); + + ELFRelocationEntry ERE(RelocOffset, Index, Type, RelocSymbol, Addend, Fixup); + Relocations[Fragment->getParent()].push_back(ERE); +} + + +uint64_t +ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm, + const MCSymbol *S) { + MCSymbolData &SD = Asm.getSymbolData(*S); + return SD.getIndex(); +} + +bool ELFObjectWriter::isInSymtab(const MCAssembler &Asm, + const MCSymbolData &Data, + bool Used, bool Renamed) { + if (Data.getFlags() & ELF_Other_Weakref) + return false; + + if (Used) + return true; + + if (Renamed) + return false; + + const MCSymbol &Symbol = Data.getSymbol(); + + if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_") + return true; + + const MCSymbol &A = Symbol.AliasedSymbol(); + if (Symbol.isVariable() && !A.isVariable() && A.isUndefined()) + return false; + + bool IsGlobal = MCELF::GetBinding(Data) == ELF::STB_GLOBAL; + if (!Symbol.isVariable() && Symbol.isUndefined() && !IsGlobal) + return false; + + if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined()) + return false; + + if (Symbol.isTemporary()) + return false; + + return true; +} + +bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isSignature, + bool isUsedInReloc) { + if (Data.isExternal()) + return false; + + const MCSymbol &Symbol = Data.getSymbol(); + const MCSymbol &RefSymbol = Symbol.AliasedSymbol(); + + if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) { + if (isSignature && !isUsedInReloc) + return true; + + return false; + } + + return true; +} + +void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm, + SectionIndexMapTy &SectionIndexMap, + const RelMapTy &RelMap) { + unsigned Index = 1; + for (MCAssembler::iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionELF &Section = + static_cast<const MCSectionELF &>(it->getSection()); + if (Section.getType() != ELF::SHT_GROUP) + continue; + SectionIndexMap[&Section] = Index++; + } + + for (MCAssembler::iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionELF &Section = + static_cast<const MCSectionELF &>(it->getSection()); + if (Section.getType() == ELF::SHT_GROUP || + Section.getType() == ELF::SHT_REL || + Section.getType() == ELF::SHT_RELA) + continue; + SectionIndexMap[&Section] = Index++; + const MCSectionELF *RelSection = RelMap.lookup(&Section); + if (RelSection) + SectionIndexMap[RelSection] = Index++; + } +} + +void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm, + const SectionIndexMapTy &SectionIndexMap, + RevGroupMapTy RevGroupMap, + unsigned NumRegularSections) { + // FIXME: Is this the correct place to do this? + // FIXME: Why is an undefined reference to _GLOBAL_OFFSET_TABLE_ needed? + if (NeedsGOT) { + StringRef Name = "_GLOBAL_OFFSET_TABLE_"; + MCSymbol *Sym = Asm.getContext().GetOrCreateSymbol(Name); + MCSymbolData &Data = Asm.getOrCreateSymbolData(*Sym); + Data.setExternal(true); + MCELF::SetBinding(Data, ELF::STB_GLOBAL); + } + + // Index 0 is always the empty string. + StringMap<uint64_t> StringIndexMap; + StringTable += '\x00'; + + // FIXME: We could optimize suffixes in strtab in the same way we + // optimize them in shstrtab. + + // Add the data for the symbols. + for (MCAssembler::symbol_iterator it = Asm.symbol_begin(), + ie = Asm.symbol_end(); it != ie; ++it) { + const MCSymbol &Symbol = it->getSymbol(); + + bool Used = UsedInReloc.count(&Symbol); + bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol); + bool isSignature = RevGroupMap.count(&Symbol); + + if (!isInSymtab(Asm, *it, + Used || WeakrefUsed || isSignature, + Renames.count(&Symbol))) + continue; + + ELFSymbolData MSD; + MSD.SymbolData = it; + const MCSymbol &RefSymbol = Symbol.AliasedSymbol(); + + // Undefined symbols are global, but this is the first place we + // are able to set it. + bool Local = isLocal(*it, isSignature, Used); + if (!Local && MCELF::GetBinding(*it) == ELF::STB_LOCAL) { + MCSymbolData &SD = Asm.getSymbolData(RefSymbol); + MCELF::SetBinding(*it, ELF::STB_GLOBAL); + MCELF::SetBinding(SD, ELF::STB_GLOBAL); + } + + if (RefSymbol.isUndefined() && !Used && WeakrefUsed) + MCELF::SetBinding(*it, ELF::STB_WEAK); + + if (it->isCommon()) { + assert(!Local); + MSD.SectionIndex = ELF::SHN_COMMON; + } else if (Symbol.isAbsolute() || RefSymbol.isVariable()) { + MSD.SectionIndex = ELF::SHN_ABS; + } else if (RefSymbol.isUndefined()) { + if (isSignature && !Used) + MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]); + else + MSD.SectionIndex = ELF::SHN_UNDEF; + } else { + const MCSectionELF &Section = + static_cast<const MCSectionELF&>(RefSymbol.getSection()); + MSD.SectionIndex = SectionIndexMap.lookup(&Section); + if (MSD.SectionIndex >= ELF::SHN_LORESERVE) + NeedsSymtabShndx = true; + assert(MSD.SectionIndex && "Invalid section index!"); + } + + // The @@@ in symbol version is replaced with @ in undefined symbols and + // @@ in defined ones. + StringRef Name = Symbol.getName(); + SmallString<32> Buf; + + size_t Pos = Name.find("@@@"); + if (Pos != StringRef::npos) { + Buf += Name.substr(0, Pos); + unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1; + Buf += Name.substr(Pos + Skip); + Name = Buf; + } + + uint64_t &Entry = StringIndexMap[Name]; + if (!Entry) { + Entry = StringTable.size(); + StringTable += Name; + StringTable += '\x00'; + } + MSD.StringIndex = Entry; + if (MSD.SectionIndex == ELF::SHN_UNDEF) + UndefinedSymbolData.push_back(MSD); + else if (Local) + LocalSymbolData.push_back(MSD); + else + ExternalSymbolData.push_back(MSD); + } + + // Symbols are required to be in lexicographic order. + array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end()); + array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end()); + array_pod_sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end()); + + // Set the symbol indices. Local symbols must come before all other + // symbols with non-local bindings. + unsigned Index = 1; + for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) + LocalSymbolData[i].SymbolData->setIndex(Index++); + + Index += NumRegularSections; + + for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) + ExternalSymbolData[i].SymbolData->setIndex(Index++); + for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) + UndefinedSymbolData[i].SymbolData->setIndex(Index++); + + if (Index >= ELF::SHN_LORESERVE) + NeedsSymtabShndx = true; +} + +void ELFObjectWriter::CreateRelocationSections(MCAssembler &Asm, + MCAsmLayout &Layout, + RelMapTy &RelMap) { + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionData &SD = *it; + if (Relocations[&SD].empty()) + continue; + + MCContext &Ctx = Asm.getContext(); + const MCSectionELF &Section = + static_cast<const MCSectionELF&>(SD.getSection()); + + const StringRef SectionName = Section.getSectionName(); + std::string RelaSectionName = hasRelocationAddend() ? ".rela" : ".rel"; + RelaSectionName += SectionName; + + unsigned EntrySize; + if (hasRelocationAddend()) + EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela); + else + EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel); + + const MCSectionELF *RelaSection = + Ctx.getELFSection(RelaSectionName, hasRelocationAddend() ? + ELF::SHT_RELA : ELF::SHT_REL, 0, + SectionKind::getReadOnly(), + EntrySize, ""); + RelMap[&Section] = RelaSection; + Asm.getOrCreateSectionData(*RelaSection); + } +} + +void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout, + const RelMapTy &RelMap) { + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionData &SD = *it; + const MCSectionELF &Section = + static_cast<const MCSectionELF&>(SD.getSection()); + + const MCSectionELF *RelaSection = RelMap.lookup(&Section); + if (!RelaSection) + continue; + MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection); + RelaSD.setAlignment(is64Bit() ? 8 : 4); + + MCDataFragment *F = new MCDataFragment(&RelaSD); + WriteRelocationsFragment(Asm, F, &*it); + } +} + +void ELFObjectWriter::WriteSecHdrEntry(uint32_t Name, uint32_t Type, + uint64_t Flags, uint64_t Address, + uint64_t Offset, uint64_t Size, + uint32_t Link, uint32_t Info, + uint64_t Alignment, + uint64_t EntrySize) { + Write32(Name); // sh_name: index into string table + Write32(Type); // sh_type + WriteWord(Flags); // sh_flags + WriteWord(Address); // sh_addr + WriteWord(Offset); // sh_offset + WriteWord(Size); // sh_size + Write32(Link); // sh_link + Write32(Info); // sh_info + WriteWord(Alignment); // sh_addralign + WriteWord(EntrySize); // sh_entsize +} + +void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm, + MCDataFragment *F, + const MCSectionData *SD) { + std::vector<ELFRelocationEntry> &Relocs = Relocations[SD]; + + // Sort the relocation entries. Most targets just sort by r_offset, but some + // (e.g., MIPS) have additional constraints. + TargetObjectWriter->sortRelocs(Asm, Relocs); + + for (unsigned i = 0, e = Relocs.size(); i != e; ++i) { + ELFRelocationEntry entry = Relocs[e - i - 1]; + + if (!entry.Index) + ; + else if (entry.Index < 0) + entry.Index = getSymbolIndexInSymbolTable(Asm, entry.Symbol); + else + entry.Index += LocalSymbolData.size(); + if (is64Bit()) { + String64(*F, entry.r_offset); + if (TargetObjectWriter->isN64()) { + String32(*F, entry.Index); + + String8(*F, TargetObjectWriter->getRSsym(entry.Type)); + String8(*F, TargetObjectWriter->getRType3(entry.Type)); + String8(*F, TargetObjectWriter->getRType2(entry.Type)); + String8(*F, TargetObjectWriter->getRType(entry.Type)); + } + else { + struct ELF::Elf64_Rela ERE64; + ERE64.setSymbolAndType(entry.Index, entry.Type); + String64(*F, ERE64.r_info); + } + if (hasRelocationAddend()) + String64(*F, entry.r_addend); + } else { + String32(*F, entry.r_offset); + + struct ELF::Elf32_Rela ERE32; + ERE32.setSymbolAndType(entry.Index, entry.Type); + String32(*F, ERE32.r_info); + + if (hasRelocationAddend()) + String32(*F, entry.r_addend); + } + } +} + +static int compareBySuffix(const void *a, const void *b) { + const MCSectionELF *secA = *static_cast<const MCSectionELF* const *>(a); + const MCSectionELF *secB = *static_cast<const MCSectionELF* const *>(b); + const StringRef &NameA = secA->getSectionName(); + const StringRef &NameB = secB->getSectionName(); + const unsigned sizeA = NameA.size(); + const unsigned sizeB = NameB.size(); + const unsigned len = std::min(sizeA, sizeB); + for (unsigned int i = 0; i < len; ++i) { + char ca = NameA[sizeA - i - 1]; + char cb = NameB[sizeB - i - 1]; + if (ca != cb) + return cb - ca; + } + + return sizeB - sizeA; +} + +void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm, + MCAsmLayout &Layout, + SectionIndexMapTy &SectionIndexMap, + const RelMapTy &RelMap) { + MCContext &Ctx = Asm.getContext(); + MCDataFragment *F; + + unsigned EntrySize = is64Bit() ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32; + + // We construct .shstrtab, .symtab and .strtab in this order to match gnu as. + const MCSectionELF *ShstrtabSection = + Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0, + SectionKind::getReadOnly()); + MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection); + ShstrtabSD.setAlignment(1); + + const MCSectionELF *SymtabSection = + Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0, + SectionKind::getReadOnly(), + EntrySize, ""); + MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection); + SymtabSD.setAlignment(is64Bit() ? 8 : 4); + + MCSectionData *SymtabShndxSD = NULL; + + if (NeedsSymtabShndx) { + const MCSectionELF *SymtabShndxSection = + Ctx.getELFSection(".symtab_shndx", ELF::SHT_SYMTAB_SHNDX, 0, + SectionKind::getReadOnly(), 4, ""); + SymtabShndxSD = &Asm.getOrCreateSectionData(*SymtabShndxSection); + SymtabShndxSD->setAlignment(4); + } + + const MCSectionELF *StrtabSection; + StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0, + SectionKind::getReadOnly()); + MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection); + StrtabSD.setAlignment(1); + + ComputeIndexMap(Asm, SectionIndexMap, RelMap); + + ShstrtabIndex = SectionIndexMap.lookup(ShstrtabSection); + SymbolTableIndex = SectionIndexMap.lookup(SymtabSection); + StringTableIndex = SectionIndexMap.lookup(StrtabSection); + + // Symbol table + F = new MCDataFragment(&SymtabSD); + MCDataFragment *ShndxF = NULL; + if (NeedsSymtabShndx) { + ShndxF = new MCDataFragment(SymtabShndxSD); + } + WriteSymbolTable(F, ShndxF, Asm, Layout, SectionIndexMap); + + F = new MCDataFragment(&StrtabSD); + F->getContents().append(StringTable.begin(), StringTable.end()); + + F = new MCDataFragment(&ShstrtabSD); + + std::vector<const MCSectionELF*> Sections; + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionELF &Section = + static_cast<const MCSectionELF&>(it->getSection()); + Sections.push_back(&Section); + } + array_pod_sort(Sections.begin(), Sections.end(), compareBySuffix); + + // Section header string table. + // + // The first entry of a string table holds a null character so skip + // section 0. + uint64_t Index = 1; + F->getContents().push_back('\x00'); + + for (unsigned int I = 0, E = Sections.size(); I != E; ++I) { + const MCSectionELF &Section = *Sections[I]; + + StringRef Name = Section.getSectionName(); + if (I != 0) { + StringRef PreviousName = Sections[I - 1]->getSectionName(); + if (PreviousName.endswith(Name)) { + SectionStringTableIndex[&Section] = Index - Name.size() - 1; + continue; + } + } + // Remember the index into the string table so we can write it + // into the sh_name field of the section header table. + SectionStringTableIndex[&Section] = Index; + + Index += Name.size() + 1; + F->getContents().append(Name.begin(), Name.end()); + F->getContents().push_back('\x00'); + } +} + +void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm, + MCAsmLayout &Layout, + GroupMapTy &GroupMap, + RevGroupMapTy &RevGroupMap, + SectionIndexMapTy &SectionIndexMap, + const RelMapTy &RelMap) { + // Create the .note.GNU-stack section if needed. + MCContext &Ctx = Asm.getContext(); + if (Asm.getNoExecStack()) { + const MCSectionELF *GnuStackSection = + Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS, 0, + SectionKind::getReadOnly()); + Asm.getOrCreateSectionData(*GnuStackSection); + } + + // Build the groups + for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); + it != ie; ++it) { + const MCSectionELF &Section = + static_cast<const MCSectionELF&>(it->getSection()); + if (!(Section.getFlags() & ELF::SHF_GROUP)) + continue; + + const MCSymbol *SignatureSymbol = Section.getGroup(); + Asm.getOrCreateSymbolData(*SignatureSymbol); + const MCSectionELF *&Group = RevGroupMap[SignatureSymbol]; + if (!Group) { + Group = Ctx.CreateELFGroupSection(); + MCSectionData &Data = Asm.getOrCreateSectionData(*Group); + Data.setAlignment(4); + MCDataFragment *F = new MCDataFragment(&Data); + String32(*F, ELF::GRP_COMDAT); + } + GroupMap[Group] = SignatureSymbol; + } + + ComputeIndexMap(Asm, SectionIndexMap, RelMap); + + // Add sections to the groups + for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); + it != ie; ++it) { + const MCSectionELF &Section = + static_cast<const MCSectionELF&>(it->getSection()); + if (!(Section.getFlags() & ELF::SHF_GROUP)) + continue; + const MCSectionELF *Group = RevGroupMap[Section.getGroup()]; + MCSectionData &Data = Asm.getOrCreateSectionData(*Group); + // FIXME: we could use the previous fragment + MCDataFragment *F = new MCDataFragment(&Data); + unsigned Index = SectionIndexMap.lookup(&Section); + String32(*F, Index); + } +} + +void ELFObjectWriter::WriteSection(MCAssembler &Asm, + const SectionIndexMapTy &SectionIndexMap, + uint32_t GroupSymbolIndex, + uint64_t Offset, uint64_t Size, + uint64_t Alignment, + const MCSectionELF &Section) { + uint64_t sh_link = 0; + uint64_t sh_info = 0; + + switch(Section.getType()) { + case ELF::SHT_DYNAMIC: + sh_link = SectionStringTableIndex[&Section]; + sh_info = 0; + break; + + case ELF::SHT_REL: + case ELF::SHT_RELA: { + const MCSectionELF *SymtabSection; + const MCSectionELF *InfoSection; + SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB, + 0, + SectionKind::getReadOnly()); + sh_link = SectionIndexMap.lookup(SymtabSection); + assert(sh_link && ".symtab not found"); + + // Remove ".rel" and ".rela" prefixes. + unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5; + StringRef SectionName = Section.getSectionName().substr(SecNameLen); + + InfoSection = Asm.getContext().getELFSection(SectionName, + ELF::SHT_PROGBITS, 0, + SectionKind::getReadOnly()); + sh_info = SectionIndexMap.lookup(InfoSection); + break; + } + + case ELF::SHT_SYMTAB: + case ELF::SHT_DYNSYM: + sh_link = StringTableIndex; + sh_info = LastLocalSymbolIndex; + break; + + case ELF::SHT_SYMTAB_SHNDX: + sh_link = SymbolTableIndex; + break; + + case ELF::SHT_PROGBITS: + case ELF::SHT_STRTAB: + case ELF::SHT_NOBITS: + case ELF::SHT_NOTE: + case ELF::SHT_NULL: + case ELF::SHT_ARM_ATTRIBUTES: + case ELF::SHT_INIT_ARRAY: + case ELF::SHT_FINI_ARRAY: + case ELF::SHT_PREINIT_ARRAY: + case ELF::SHT_X86_64_UNWIND: + case ELF::SHT_MIPS_REGINFO: + case ELF::SHT_MIPS_OPTIONS: + // Nothing to do. + break; + + case ELF::SHT_GROUP: + sh_link = SymbolTableIndex; + sh_info = GroupSymbolIndex; + break; + + default: + assert(0 && "FIXME: sh_type value not supported!"); + break; + } + + if (TargetObjectWriter->getEMachine() == ELF::EM_ARM && + Section.getType() == ELF::SHT_ARM_EXIDX) { + StringRef SecName(Section.getSectionName()); + if (SecName == ".ARM.exidx") { + sh_link = SectionIndexMap.lookup( + Asm.getContext().getELFSection(".text", + ELF::SHT_PROGBITS, + ELF::SHF_EXECINSTR | ELF::SHF_ALLOC, + SectionKind::getText())); + } else if (SecName.startswith(".ARM.exidx")) { + sh_link = SectionIndexMap.lookup( + Asm.getContext().getELFSection(SecName.substr(sizeof(".ARM.exidx") - 1), + ELF::SHT_PROGBITS, + ELF::SHF_EXECINSTR | ELF::SHF_ALLOC, + SectionKind::getText())); + } + } + + WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(), + Section.getFlags(), 0, Offset, Size, sh_link, sh_info, + Alignment, Section.getEntrySize()); +} + +bool ELFObjectWriter::IsELFMetaDataSection(const MCSectionData &SD) { + return SD.getOrdinal() == ~UINT32_C(0) && + !SD.getSection().isVirtualSection(); +} + +uint64_t ELFObjectWriter::DataSectionSize(const MCSectionData &SD) { + uint64_t Ret = 0; + for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e; + ++i) { + const MCFragment &F = *i; + assert(F.getKind() == MCFragment::FT_Data); + Ret += cast<MCDataFragment>(F).getContents().size(); + } + return Ret; +} + +uint64_t ELFObjectWriter::GetSectionFileSize(const MCAsmLayout &Layout, + const MCSectionData &SD) { + if (IsELFMetaDataSection(SD)) + return DataSectionSize(SD); + return Layout.getSectionFileSize(&SD); +} + +uint64_t ELFObjectWriter::GetSectionAddressSize(const MCAsmLayout &Layout, + const MCSectionData &SD) { + if (IsELFMetaDataSection(SD)) + return DataSectionSize(SD); + return Layout.getSectionAddressSize(&SD); +} + +void ELFObjectWriter::WriteDataSectionData(MCAssembler &Asm, + const MCAsmLayout &Layout, + const MCSectionELF &Section) { + const MCSectionData &SD = Asm.getOrCreateSectionData(Section); + + uint64_t Padding = OffsetToAlignment(OS.tell(), SD.getAlignment()); + WriteZeros(Padding); + + if (IsELFMetaDataSection(SD)) { + for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e; + ++i) { + const MCFragment &F = *i; + assert(F.getKind() == MCFragment::FT_Data); + WriteBytes(cast<MCDataFragment>(F).getContents()); + } + } else { + Asm.writeSectionData(&SD, Layout); + } +} + +void ELFObjectWriter::WriteSectionHeader(MCAssembler &Asm, + const GroupMapTy &GroupMap, + const MCAsmLayout &Layout, + const SectionIndexMapTy &SectionIndexMap, + const SectionOffsetMapTy &SectionOffsetMap) { + const unsigned NumSections = Asm.size() + 1; + + std::vector<const MCSectionELF*> Sections; + Sections.resize(NumSections - 1); + + for (SectionIndexMapTy::const_iterator i= + SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) { + const std::pair<const MCSectionELF*, uint32_t> &p = *i; + Sections[p.second - 1] = p.first; + } + + // Null section first. + uint64_t FirstSectionSize = + NumSections >= ELF::SHN_LORESERVE ? NumSections : 0; + uint32_t FirstSectionLink = + ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0; + WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0); + + for (unsigned i = 0; i < NumSections - 1; ++i) { + const MCSectionELF &Section = *Sections[i]; + const MCSectionData &SD = Asm.getOrCreateSectionData(Section); + uint32_t GroupSymbolIndex; + if (Section.getType() != ELF::SHT_GROUP) + GroupSymbolIndex = 0; + else + GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm, + GroupMap.lookup(&Section)); + + uint64_t Size = GetSectionAddressSize(Layout, SD); + + WriteSection(Asm, SectionIndexMap, GroupSymbolIndex, + SectionOffsetMap.lookup(&Section), Size, + SD.getAlignment(), Section); + } +} + +void ELFObjectWriter::ComputeSectionOrder(MCAssembler &Asm, + std::vector<const MCSectionELF*> &Sections) { + for (MCAssembler::iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionELF &Section = + static_cast<const MCSectionELF &>(it->getSection()); + if (Section.getType() == ELF::SHT_GROUP) + Sections.push_back(&Section); + } + + for (MCAssembler::iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionELF &Section = + static_cast<const MCSectionELF &>(it->getSection()); + if (Section.getType() != ELF::SHT_GROUP && + Section.getType() != ELF::SHT_REL && + Section.getType() != ELF::SHT_RELA) + Sections.push_back(&Section); + } + + for (MCAssembler::iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionELF &Section = + static_cast<const MCSectionELF &>(it->getSection()); + if (Section.getType() == ELF::SHT_REL || + Section.getType() == ELF::SHT_RELA) + Sections.push_back(&Section); + } +} + +void ELFObjectWriter::WriteObject(MCAssembler &Asm, + const MCAsmLayout &Layout) { + GroupMapTy GroupMap; + RevGroupMapTy RevGroupMap; + SectionIndexMapTy SectionIndexMap; + + unsigned NumUserSections = Asm.size(); + + DenseMap<const MCSectionELF*, const MCSectionELF*> RelMap; + CreateRelocationSections(Asm, const_cast<MCAsmLayout&>(Layout), RelMap); + + const unsigned NumUserAndRelocSections = Asm.size(); + CreateIndexedSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap, + RevGroupMap, SectionIndexMap, RelMap); + const unsigned AllSections = Asm.size(); + const unsigned NumIndexedSections = AllSections - NumUserAndRelocSections; + + unsigned NumRegularSections = NumUserSections + NumIndexedSections; + + // Compute symbol table information. + ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap, NumRegularSections); + + + WriteRelocations(Asm, const_cast<MCAsmLayout&>(Layout), RelMap); + + CreateMetadataSections(const_cast<MCAssembler&>(Asm), + const_cast<MCAsmLayout&>(Layout), + SectionIndexMap, + RelMap); + + uint64_t NaturalAlignment = is64Bit() ? 8 : 4; + uint64_t HeaderSize = is64Bit() ? sizeof(ELF::Elf64_Ehdr) : + sizeof(ELF::Elf32_Ehdr); + uint64_t FileOff = HeaderSize; + + std::vector<const MCSectionELF*> Sections; + ComputeSectionOrder(Asm, Sections); + unsigned NumSections = Sections.size(); + SectionOffsetMapTy SectionOffsetMap; + for (unsigned i = 0; i < NumRegularSections + 1; ++i) { + const MCSectionELF &Section = *Sections[i]; + const MCSectionData &SD = Asm.getOrCreateSectionData(Section); + + FileOff = RoundUpToAlignment(FileOff, SD.getAlignment()); + + // Remember the offset into the file for this section. + SectionOffsetMap[&Section] = FileOff; + + // Get the size of the section in the output file (including padding). + FileOff += GetSectionFileSize(Layout, SD); + } + + FileOff = RoundUpToAlignment(FileOff, NaturalAlignment); + + const unsigned SectionHeaderOffset = FileOff - HeaderSize; + + uint64_t SectionHeaderEntrySize = is64Bit() ? + sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr); + FileOff += (NumSections + 1) * SectionHeaderEntrySize; + + for (unsigned i = NumRegularSections + 1; i < NumSections; ++i) { + const MCSectionELF &Section = *Sections[i]; + const MCSectionData &SD = Asm.getOrCreateSectionData(Section); + + FileOff = RoundUpToAlignment(FileOff, SD.getAlignment()); + + // Remember the offset into the file for this section. + SectionOffsetMap[&Section] = FileOff; + + // Get the size of the section in the output file (including padding). + FileOff += GetSectionFileSize(Layout, SD); + } + + // Write out the ELF header ... + WriteHeader(Asm, SectionHeaderOffset, NumSections + 1); + + // ... then the regular sections ... + // + because of .shstrtab + for (unsigned i = 0; i < NumRegularSections + 1; ++i) + WriteDataSectionData(Asm, Layout, *Sections[i]); + + uint64_t Padding = OffsetToAlignment(OS.tell(), NaturalAlignment); + WriteZeros(Padding); + + // ... then the section header table ... + WriteSectionHeader(Asm, GroupMap, Layout, SectionIndexMap, + SectionOffsetMap); + + // ... and then the remaining sections ... + for (unsigned i = NumRegularSections + 1; i < NumSections; ++i) + WriteDataSectionData(Asm, Layout, *Sections[i]); +} + +bool +ELFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, + const MCSymbolData &DataA, + const MCFragment &FB, + bool InSet, + bool IsPCRel) const { + if (DataA.getFlags() & ELF_STB_Weak) + return false; + return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl( + Asm, DataA, FB,InSet, IsPCRel); +} + +MCObjectWriter *llvm::createELFObjectWriter(MCELFObjectTargetWriter *MOTW, + raw_ostream &OS, + bool IsLittleEndian) { + return new ELFObjectWriter(MOTW, OS, IsLittleEndian); +} |
