//===- 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/ADT/OwningPtr.h" #include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/STLExtras.h" #include "llvm/ADT/StringMap.h" #include "llvm/ADT/Twine.h" #include "llvm/MC/MCAssembler.h" #include "llvm/MC/MCAsmLayout.h" #include "llvm/MC/MCContext.h" #include "llvm/MC/MCELFSymbolFlags.h" #include "llvm/MC/MCExpr.h" #include "llvm/MC/MCELFObjectWriter.h" #include "llvm/MC/MCObjectWriter.h" #include "llvm/MC/MCSectionELF.h" #include "llvm/MC/MCSymbol.h" #include "llvm/MC/MCValue.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/ELF.h" #include "llvm/Target/TargetAsmBackend.h" #include "llvm/ADT/StringSwitch.h" #include "../Target/X86/X86FixupKinds.h" #include "../Target/ARM/ARMFixupKinds.h" #include using namespace llvm; static unsigned GetType(const MCSymbolData &SD) { uint32_t Type = (SD.getFlags() & (0xf << ELF_STT_Shift)) >> ELF_STT_Shift; assert(Type == ELF::STT_NOTYPE || Type == ELF::STT_OBJECT || Type == ELF::STT_FUNC || Type == ELF::STT_SECTION || Type == ELF::STT_FILE || Type == ELF::STT_COMMON || Type == ELF::STT_TLS); return Type; } static unsigned GetBinding(const MCSymbolData &SD) { uint32_t Binding = (SD.getFlags() & (0xf << ELF_STB_Shift)) >> ELF_STB_Shift; assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL || Binding == ELF::STB_WEAK); return Binding; } static void SetBinding(MCSymbolData &SD, unsigned Binding) { assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL || Binding == ELF::STB_WEAK); uint32_t OtherFlags = SD.getFlags() & ~(0xf << ELF_STB_Shift); SD.setFlags(OtherFlags | (Binding << ELF_STB_Shift)); } static unsigned GetVisibility(MCSymbolData &SD) { unsigned Visibility = (SD.getFlags() & (0xf << ELF_STV_Shift)) >> ELF_STV_Shift; assert(Visibility == ELF::STV_DEFAULT || Visibility == ELF::STV_INTERNAL || Visibility == ELF::STV_HIDDEN || Visibility == ELF::STV_PROTECTED); return Visibility; } static bool RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant) { switch (Variant) { default: return false; case MCSymbolRefExpr::VK_GOT: case MCSymbolRefExpr::VK_PLT: case MCSymbolRefExpr::VK_GOTPCREL: 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; } } static bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) { const MCFixupKindInfo &FKI = Asm.getBackend().getFixupKindInfo((MCFixupKind) Kind); return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel; } namespace { class ELFObjectWriter : public MCObjectWriter { protected: /*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 (GetType(*SymbolData) == ELF::STT_FILE) return true; if (GetType(*RHS.SymbolData) == ELF::STT_FILE) return false; return SymbolData->getSymbol().getName() < RHS.SymbolData->getSymbol().getName(); } }; /// @name Relocation Data /// @{ struct ELFRelocationEntry { // Make these big enough for both 32-bit and 64-bit uint64_t r_offset; int Index; unsigned Type; const MCSymbol *Symbol; uint64_t r_addend; ELFRelocationEntry() : r_offset(0), Index(0), Type(0), Symbol(0), r_addend(0) {} ELFRelocationEntry(uint64_t RelocOffset, int Idx, unsigned RelType, const MCSymbol *Sym, uint64_t Addend) : r_offset(RelocOffset), Index(Idx), Type(RelType), Symbol(Sym), r_addend(Addend) {} // Support lexicographic sorting. bool operator<(const ELFRelocationEntry &RE) const { return RE.r_offset < r_offset; } }; /// The target specific ELF writer instance. llvm::OwningPtr TargetObjectWriter; SmallPtrSet UsedInReloc; SmallPtrSet WeakrefUsedInReloc; DenseMap Renames; llvm::DenseMap > Relocations; DenseMap SectionStringTableIndex; /// @} /// @name Symbol Table Data /// @{ SmallString<256> StringTable; std::vector LocalSymbolData; std::vector ExternalSymbolData; std::vector 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; // For arch-specific emission of explicit reloc symbol virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm, const MCValue &Target, const MCFragment &F, bool IsBSS) const { return NULL; } bool is64Bit() const { return TargetObjectWriter->is64Bit(); } bool hasRelocationAddend() const { return TargetObjectWriter->hasRelocationAddend(); } 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() += StringRef(buf, 1); } void String16(MCDataFragment &F, uint16_t Value) { char buf[2]; if (isLittleEndian()) StringLE16(buf, Value); else StringBE16(buf, Value); F.getContents() += StringRef(buf, 2); } void String32(MCDataFragment &F, uint32_t Value) { char buf[4]; if (isLittleEndian()) StringLE32(buf, Value); else StringBE32(buf, Value); F.getContents() += StringRef(buf, 4); } void String64(MCDataFragment &F, uint64_t Value) { char buf[8]; if (isLittleEndian()) StringLE64(buf, Value); else StringBE64(buf, Value); F.getContents() += StringRef(buf, 8); } virtual void WriteHeader(uint64_t SectionDataSize, unsigned NumberOfSections); /// Default e_flags = 0 virtual void WriteEFlags() { Write32(0); } virtual 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); virtual void WriteSymbol(MCDataFragment *SymtabF, MCDataFragment *ShndxF, ELFSymbolData &MSD, const MCAsmLayout &Layout); typedef DenseMap SectionIndexMapTy; virtual 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); virtual uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm, const MCSymbol *S); // Map from a group section to the signature symbol typedef DenseMap GroupMapTy; // Map from a signature symbol to the group section typedef DenseMap RevGroupMapTy; /// ComputeSymbolTable - Compute the symbol table data /// /// \param StringTable [out] - The string table data. /// \param StringIndexMap [out] - Map from symbol names to offsets in the /// string table. virtual void ComputeSymbolTable(MCAssembler &Asm, const SectionIndexMapTy &SectionIndexMap, RevGroupMapTy RevGroupMap); virtual void ComputeIndexMap(MCAssembler &Asm, SectionIndexMapTy &SectionIndexMap); virtual void WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout, const MCSectionData &SD); virtual void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout) { for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) { WriteRelocation(Asm, Layout, *it); } } virtual void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout, const SectionIndexMapTy &SectionIndexMap); // Create the sections that show up in the symbol table. Currently // those are the .note.GNU-stack section and the group sections. virtual void CreateIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout, GroupMapTy &GroupMap, RevGroupMapTy &RevGroupMap); virtual void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout); virtual 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); virtual 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); virtual void WriteSection(MCAssembler &Asm, const SectionIndexMapTy &SectionIndexMap, uint32_t GroupSymbolIndex, uint64_t Offset, uint64_t Size, uint64_t Alignment, const MCSectionELF &Section); protected: virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup, bool IsPCRel, bool IsRelocWithSymbol, int64_t Addend) = 0; }; //===- X86ELFObjectWriter -------------------------------------------===// class X86ELFObjectWriter : public ELFObjectWriter { public: X86ELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_ostream &_OS, bool IsLittleEndian); virtual ~X86ELFObjectWriter(); protected: virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup, bool IsPCRel, bool IsRelocWithSymbol, int64_t Addend); }; //===- ARMELFObjectWriter -------------------------------------------===// class ARMELFObjectWriter : public ELFObjectWriter { public: // FIXME: MCAssembler can't yet return the Subtarget, enum { DefaultEABIVersion = 0x05000000U }; ARMELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_ostream &_OS, bool IsLittleEndian); virtual ~ARMELFObjectWriter(); virtual void WriteEFlags(); protected: virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm, const MCValue &Target, const MCFragment &F, bool IsBSS) const; virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup, bool IsPCRel, bool IsRelocWithSymbol, int64_t Addend); }; //===- MBlazeELFObjectWriter -------------------------------------------===// class MBlazeELFObjectWriter : public ELFObjectWriter { public: MBlazeELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_ostream &_OS, bool IsLittleEndian); virtual ~MBlazeELFObjectWriter(); protected: virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup, bool IsPCRel, bool IsRelocWithSymbol, int64_t Addend); }; } ELFObjectWriter::~ELFObjectWriter() {} // Emit the ELF header. void ELFObjectWriter::WriteHeader(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] switch (TargetObjectWriter->getOSType()) { case Triple::FreeBSD: Write8(ELF::ELFOSABI_FREEBSD); break; case Triple::Linux: Write8(ELF::ELFOSABI_LINUX); break; default: Write8(ELF::ELFOSABI_NONE); break; } 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 WriteEFlags(); // 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(0); else Write16(NumberOfSections); // e_shstrndx = Section # of '.shstrtab' if (NumberOfSections >= 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 } } static uint64_t 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()) 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()); SetBinding(*it, 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(); uint8_t Binding = GetBinding(OrigData); uint8_t Visibility = GetVisibility(OrigData); uint8_t Type = GetType(Data); uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift); uint8_t 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(i->getSection()); if (Section.getType() == ELF::SHT_RELA || Section.getType() == ELF::SHT_REL || Section.getType() == ELF::SHT_STRTAB || Section.getType() == ELF::SHT_SYMTAB) 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 (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 (GetBinding(Data) == ELF::STB_LOCAL) LastLocalSymbolIndex++; } } const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm, const MCValue &Target, const MCFragment &F) 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 &ASymbol; } if (SD.isExternal()) { if (Renamed) return Renamed; return &Symbol; } const MCSectionELF &Section = static_cast(ASymbol.getSection()); const SectionKind secKind = Section.getKind(); if (secKind.isBSS()) return ExplicitRelSym(Asm, Target, F, true); if (secKind.isThreadLocal()) { if (Renamed) return Renamed; return &Symbol; } MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind(); const MCSectionELF &Sec2 = static_cast(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 NULL; if (Renamed) return Renamed; return &Symbol; } return ExplicitRelSym(Asm, Target, F, false); } 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); 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); // Ofeset 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(); Index = F->getParent()->getOrdinal() + 1; // Offset of the symbol in the section Value += Layout.getSymbolOffset(&SD); } else { if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref) WeakrefUsedInReloc.insert(RelocSymbol); else UsedInReloc.insert(RelocSymbol); Index = -1; } Addend = Value; // Compensate for the addend on i386. if (is64Bit()) Value = 0; } FixedValue = Value; unsigned Type = GetRelocType(Target, Fixup, IsPCRel, (RelocSymbol != 0), Addend); uint64_t RelocOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset(); if (!hasRelocationAddend()) Addend = 0; ELFRelocationEntry ERE(RelocOffset, Index, Type, RelocSymbol, Addend); Relocations[Fragment->getParent()].push_back(ERE); } uint64_t ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm, const MCSymbol *S) { MCSymbolData &SD = Asm.getSymbolData(*S); return SD.getIndex(); } static bool 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 (!A.isVariable() && A.isUndefined() && !Data.isCommon()) return false; if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined()) return false; if (Symbol.isTemporary()) return false; return true; } static bool 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) { unsigned Index = 1; for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) { const MCSectionELF &Section = static_cast(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(it->getSection()); if (Section.getType() == ELF::SHT_GROUP) continue; SectionIndexMap[&Section] = Index++; } } void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm, const SectionIndexMapTy &SectionIndexMap, RevGroupMapTy RevGroupMap) { // FIXME: Is this the correct place to do this? if (NeedsGOT) { llvm::StringRef Name = "_GLOBAL_OFFSET_TABLE_"; MCSymbol *Sym = Asm.getContext().GetOrCreateSymbol(Name); MCSymbolData &Data = Asm.getOrCreateSymbolData(*Sym); Data.setExternal(true); SetBinding(Data, ELF::STB_GLOBAL); } // Build section lookup table. int NumRegularSections = Asm.size(); // Index 0 is always the empty string. StringMap StringIndexMap; StringTable += '\x00'; // 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 && GetBinding(*it) == ELF::STB_LOCAL) { MCSymbolData &SD = Asm.getSymbolData(RefSymbol); SetBinding(*it, ELF::STB_GLOBAL); SetBinding(SD, ELF::STB_GLOBAL); } if (RefSymbol.isUndefined() && !Used && WeakrefUsed) 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(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++); } void ELFObjectWriter::WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout, const MCSectionData &SD) { if (!Relocations[&SD].empty()) { MCContext &Ctx = Asm.getContext(); const MCSectionELF *RelaSection; const MCSectionELF &Section = static_cast(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); RelaSection = Ctx.getELFSection(RelaSectionName, hasRelocationAddend() ? ELF::SHT_RELA : ELF::SHT_REL, 0, SectionKind::getReadOnly(), EntrySize, ""); MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection); RelaSD.setAlignment(is64Bit() ? 8 : 4); MCDataFragment *F = new MCDataFragment(&RelaSD); WriteRelocationsFragment(Asm, F, &SD); } } 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 &Relocs = Relocations[SD]; // sort by the r_offset just like gnu as does array_pod_sort(Relocs.begin(), Relocs.end()); 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); 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); } } } void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout, const SectionIndexMapTy &SectionIndexMap) { 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); ShstrtabIndex = Asm.size(); const MCSectionELF *SymtabSection = Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0, SectionKind::getReadOnly(), EntrySize, ""); MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection); SymtabSD.setAlignment(is64Bit() ? 8 : 4); SymbolTableIndex = Asm.size(); 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 MCSection *StrtabSection; StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0, SectionKind::getReadOnly()); MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection); StrtabSD.setAlignment(1); StringTableIndex = Asm.size(); WriteRelocations(Asm, Layout); // 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); // 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() += '\x00'; StringMap SecStringMap; for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) { const MCSectionELF &Section = static_cast(it->getSection()); // FIXME: We could merge suffixes like in .text and .rela.text. StringRef Name = Section.getSectionName(); if (SecStringMap.count(Name)) { SectionStringTableIndex[&Section] = SecStringMap[Name]; 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; SecStringMap[Name] = Index; Index += Name.size() + 1; F->getContents() += Name; F->getContents() += '\x00'; } } bool ELFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, const MCSymbolData &DataA, const MCFragment &FB, bool InSet, bool IsPCRel) const { // FIXME: This is in here just to match gnu as output. If the two ends // are in the same section, there is nothing that the linker can do to // break it. if (DataA.isExternal()) return false; const MCSection &SecA = DataA.getSymbol().AliasedSymbol().getSection(); const MCSection &SecB = FB.getParent()->getSection(); // On ELF A - B is absolute if A and B are in the same section. return &SecA == &SecB; } void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout, GroupMapTy &GroupMap, RevGroupMapTy &RevGroupMap) { // 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(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; } // Add sections to the groups unsigned Index = 1; unsigned NumGroups = RevGroupMap.size(); for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it, ++Index) { const MCSectionELF &Section = static_cast(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); String32(*F, NumGroups + 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: // 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; } WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(), Section.getFlags(), 0, Offset, Size, sh_link, sh_info, Alignment, Section.getEntrySize()); } static bool IsELFMetaDataSection(const MCSectionData &SD) { return SD.getOrdinal() == ~UINT32_C(0) && !SD.getSection().isVirtualSection(); } static uint64_t 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(F).getContents().size(); } return Ret; } static uint64_t GetSectionFileSize(const MCAsmLayout &Layout, const MCSectionData &SD) { if (IsELFMetaDataSection(SD)) return DataSectionSize(SD); return Layout.getSectionFileSize(&SD); } static uint64_t GetSectionAddressSize(const MCAsmLayout &Layout, const MCSectionData &SD) { if (IsELFMetaDataSection(SD)) return DataSectionSize(SD); return Layout.getSectionAddressSize(&SD); } static void WriteDataSectionData(ELFObjectWriter *W, const MCSectionData &SD) { for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e; ++i) { const MCFragment &F = *i; assert(F.getKind() == MCFragment::FT_Data); W->WriteBytes(cast(F).getContents().str()); } } void ELFObjectWriter::WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) { GroupMapTy GroupMap; RevGroupMapTy RevGroupMap; CreateIndexedSections(Asm, const_cast(Layout), GroupMap, RevGroupMap); SectionIndexMapTy SectionIndexMap; ComputeIndexMap(Asm, SectionIndexMap); // Compute symbol table information. ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap); CreateMetadataSections(const_cast(Asm), const_cast(Layout), SectionIndexMap); // Update to include the metadata sections. ComputeIndexMap(Asm, SectionIndexMap); // Add 1 for the null section. unsigned NumSections = Asm.size() + 1; uint64_t NaturalAlignment = is64Bit() ? 8 : 4; uint64_t HeaderSize = is64Bit() ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr); uint64_t FileOff = HeaderSize; std::vector Sections; Sections.resize(NumSections); for (SectionIndexMapTy::const_iterator i= SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) { const std::pair &p = *i; Sections[p.second] = p.first; } for (unsigned i = 1; i < NumSections; ++i) { const MCSectionELF &Section = *Sections[i]; const MCSectionData &SD = Asm.getOrCreateSectionData(Section); FileOff = RoundUpToAlignment(FileOff, SD.getAlignment()); // Get the size of the section in the output file (including padding). FileOff += GetSectionFileSize(Layout, SD); } FileOff = RoundUpToAlignment(FileOff, NaturalAlignment); // Write out the ELF header ... WriteHeader(FileOff - HeaderSize, NumSections); FileOff = HeaderSize; // ... then all of the sections ... DenseMap SectionOffsetMap; for (unsigned i = 1; i < NumSections; ++i) { const MCSectionELF &Section = *Sections[i]; const MCSectionData &SD = Asm.getOrCreateSectionData(Section); uint64_t Padding = OffsetToAlignment(FileOff, SD.getAlignment()); WriteZeros(Padding); FileOff += Padding; // Remember the offset into the file for this section. SectionOffsetMap[&Section] = FileOff; FileOff += GetSectionFileSize(Layout, SD); if (IsELFMetaDataSection(SD)) WriteDataSectionData(this, SD); else Asm.WriteSectionData(&SD, Layout); } uint64_t Padding = OffsetToAlignment(FileOff, NaturalAlignment); WriteZeros(Padding); FileOff += Padding; // ... and then the section header table. // Should we align the section header table? // // 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 = 1; i < NumSections; ++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[&Section]); uint64_t Size = GetSectionAddressSize(Layout, SD); WriteSection(Asm, SectionIndexMap, GroupSymbolIndex, SectionOffsetMap[&Section], Size, SD.getAlignment(), Section); } } MCObjectWriter *llvm::createELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_ostream &OS, bool IsLittleEndian) { switch (MOTW->getEMachine()) { case ELF::EM_386: case ELF::EM_X86_64: return new X86ELFObjectWriter(MOTW, OS, IsLittleEndian); break; case ELF::EM_ARM: return new ARMELFObjectWriter(MOTW, OS, IsLittleEndian); break; case ELF::EM_MBLAZE: return new MBlazeELFObjectWriter(MOTW, OS, IsLittleEndian); break; default: llvm_unreachable("Unsupported architecture"); break; } } /// START OF SUBCLASSES for ELFObjectWriter //===- ARMELFObjectWriter -------------------------------------------===// ARMELFObjectWriter::ARMELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_ostream &_OS, bool IsLittleEndian) : ELFObjectWriter(MOTW, _OS, IsLittleEndian) {} ARMELFObjectWriter::~ARMELFObjectWriter() {} // FIXME: get the real EABI Version from the Triple. void ARMELFObjectWriter::WriteEFlags() { Write32(ELF::EF_ARM_EABIMASK & DefaultEABIVersion); } // In ARM, _MergedGlobals and other most symbols get emitted directly. // I.e. not as an offset to a section symbol. // This code is a first-cut approximation of what ARM/gcc does. const MCSymbol *ARMELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm, const MCValue &Target, const MCFragment &F, bool IsBSS) const { const MCSymbol &Symbol = Target.getSymA()->getSymbol(); bool EmitThisSym = false; if (IsBSS) { EmitThisSym = StringSwitch(Symbol.getName()) .Case("_MergedGlobals", true) .Default(false); } else { EmitThisSym = StringSwitch(Symbol.getName()) .Case("_MergedGlobals", true) .StartsWith(".L.str", true) .Default(false); } if (EmitThisSym) return &Symbol; if (! Symbol.isTemporary()) return &Symbol; return NULL; } unsigned ARMELFObjectWriter::GetRelocType(const MCValue &Target, const MCFixup &Fixup, bool IsPCRel, bool IsRelocWithSymbol, int64_t Addend) { MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ? MCSymbolRefExpr::VK_None : Target.getSymA()->getKind(); unsigned Type = 0; if (IsPCRel) { switch ((unsigned)Fixup.getKind()) { default: assert(0 && "Unimplemented"); case FK_Data_4: switch (Modifier) { default: llvm_unreachable("Unsupported Modifier"); case MCSymbolRefExpr::VK_None: Type = ELF::R_ARM_BASE_PREL; break; case MCSymbolRefExpr::VK_ARM_TLSGD: assert(0 && "unimplemented"); break; case MCSymbolRefExpr::VK_ARM_GOTTPOFF: Type = ELF::R_ARM_TLS_IE32; break; } break; case ARM::fixup_arm_uncondbranch: switch (Modifier) { case MCSymbolRefExpr::VK_ARM_PLT: Type = ELF::R_ARM_PLT32; break; default: Type = ELF::R_ARM_CALL; break; } break; case ARM::fixup_arm_condbranch: Type = ELF::R_ARM_JUMP24; break; case ARM::fixup_arm_movt_hi16: case ARM::fixup_arm_movt_hi16_pcrel: Type = ELF::R_ARM_MOVT_PREL; break; case ARM::fixup_arm_movw_lo16: case ARM::fixup_arm_movw_lo16_pcrel: Type = ELF::R_ARM_MOVW_PREL_NC; break; case ARM::fixup_t2_movt_hi16: case ARM::fixup_t2_movt_hi16_pcrel: Type = ELF::R_ARM_THM_MOVT_PREL; break; case ARM::fixup_t2_movw_lo16: case ARM::fixup_t2_movw_lo16_pcrel: Type = ELF::R_ARM_THM_MOVW_PREL_NC; break; } } else { switch ((unsigned)Fixup.getKind()) { default: llvm_unreachable("invalid fixup kind!"); case FK_Data_4: switch (Modifier) { default: llvm_unreachable("Unsupported Modifier"); break; case MCSymbolRefExpr::VK_ARM_GOT: Type = ELF::R_ARM_GOT_BREL; break; case MCSymbolRefExpr::VK_ARM_TLSGD: Type = ELF::R_ARM_TLS_GD32; break; case MCSymbolRefExpr::VK_ARM_TPOFF: Type = ELF::R_ARM_TLS_LE32; break; case MCSymbolRefExpr::VK_ARM_GOTTPOFF: Type = ELF::R_ARM_TLS_IE32; break; case MCSymbolRefExpr::VK_None: Type = ELF::R_ARM_ABS32; break; case MCSymbolRefExpr::VK_ARM_GOTOFF: Type = ELF::R_ARM_GOTOFF32; break; } break; case ARM::fixup_arm_ldst_pcrel_12: case ARM::fixup_arm_pcrel_10: case ARM::fixup_arm_adr_pcrel_12: case ARM::fixup_arm_thumb_bl: case ARM::fixup_arm_thumb_cb: case ARM::fixup_arm_thumb_cp: case ARM::fixup_arm_thumb_br: assert(0 && "Unimplemented"); break; case ARM::fixup_arm_uncondbranch: Type = ELF::R_ARM_CALL; break; case ARM::fixup_arm_condbranch: Type = ELF::R_ARM_JUMP24; break; case ARM::fixup_arm_movt_hi16: Type = ELF::R_ARM_MOVT_ABS; break; case ARM::fixup_arm_movw_lo16: Type = ELF::R_ARM_MOVW_ABS_NC; break; case ARM::fixup_t2_movt_hi16: Type = ELF::R_ARM_THM_MOVT_ABS; break; case ARM::fixup_t2_movw_lo16: Type = ELF::R_ARM_THM_MOVW_ABS_NC; break; } } if (RelocNeedsGOT(Modifier)) NeedsGOT = true; return Type; } //===- MBlazeELFObjectWriter -------------------------------------------===// MBlazeELFObjectWriter::MBlazeELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_ostream &_OS, bool IsLittleEndian) : ELFObjectWriter(MOTW, _OS, IsLittleEndian) { } MBlazeELFObjectWriter::~MBlazeELFObjectWriter() { } unsigned MBlazeELFObjectWriter::GetRelocType(const MCValue &Target, const MCFixup &Fixup, bool IsPCRel, bool IsRelocWithSymbol, int64_t Addend) { // determine the type of the relocation unsigned Type; if (IsPCRel) { switch ((unsigned)Fixup.getKind()) { default: llvm_unreachable("Unimplemented"); case FK_PCRel_4: Type = ELF::R_MICROBLAZE_64_PCREL; break; case FK_PCRel_2: Type = ELF::R_MICROBLAZE_32_PCREL; break; } } else { switch ((unsigned)Fixup.getKind()) { default: llvm_unreachable("invalid fixup kind!"); case FK_Data_4: Type = ((IsRelocWithSymbol || Addend !=0) ? ELF::R_MICROBLAZE_32 : ELF::R_MICROBLAZE_64); break; case FK_Data_2: Type = ELF::R_MICROBLAZE_32; break; } } return Type; } //===- X86ELFObjectWriter -------------------------------------------===// X86ELFObjectWriter::X86ELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_ostream &_OS, bool IsLittleEndian) : ELFObjectWriter(MOTW, _OS, IsLittleEndian) {} X86ELFObjectWriter::~X86ELFObjectWriter() {} unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target, const MCFixup &Fixup, bool IsPCRel, bool IsRelocWithSymbol, int64_t Addend) { // determine the type of the relocation MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ? MCSymbolRefExpr::VK_None : Target.getSymA()->getKind(); unsigned Type; if (is64Bit()) { if (IsPCRel) { switch ((unsigned)Fixup.getKind()) { default: llvm_unreachable("invalid fixup kind!"); case FK_PCRel_8: assert(Modifier == MCSymbolRefExpr::VK_None); Type = ELF::R_X86_64_PC64; break; case X86::reloc_signed_4byte: case X86::reloc_riprel_4byte_movq_load: case FK_Data_4: // FIXME? case X86::reloc_riprel_4byte: case FK_PCRel_4: switch (Modifier) { default: llvm_unreachable("Unimplemented"); case MCSymbolRefExpr::VK_None: Type = ELF::R_X86_64_PC32; break; case MCSymbolRefExpr::VK_PLT: Type = ELF::R_X86_64_PLT32; break; case MCSymbolRefExpr::VK_GOTPCREL: Type = ELF::R_X86_64_GOTPCREL; break; case MCSymbolRefExpr::VK_GOTTPOFF: Type = ELF::R_X86_64_GOTTPOFF; break; case MCSymbolRefExpr::VK_TLSGD: Type = ELF::R_X86_64_TLSGD; break; case MCSymbolRefExpr::VK_TLSLD: Type = ELF::R_X86_64_TLSLD; break; } break; case FK_PCRel_2: assert(Modifier == MCSymbolRefExpr::VK_None); Type = ELF::R_X86_64_PC16; break; } } else { switch ((unsigned)Fixup.getKind()) { default: llvm_unreachable("invalid fixup kind!"); case FK_Data_8: Type = ELF::R_X86_64_64; break; case X86::reloc_signed_4byte: assert(isInt<32>(Target.getConstant())); switch (Modifier) { default: llvm_unreachable("Unimplemented"); case MCSymbolRefExpr::VK_None: Type = ELF::R_X86_64_32S; break; case MCSymbolRefExpr::VK_GOT: Type = ELF::R_X86_64_GOT32; break; case MCSymbolRefExpr::VK_GOTPCREL: Type = ELF::R_X86_64_GOTPCREL; break; case MCSymbolRefExpr::VK_TPOFF: Type = ELF::R_X86_64_TPOFF32; break; case MCSymbolRefExpr::VK_DTPOFF: Type = ELF::R_X86_64_DTPOFF32; break; } break; case FK_Data_4: Type = ELF::R_X86_64_32; break; case FK_Data_2: Type = ELF::R_X86_64_16; break; case FK_PCRel_1: case FK_Data_1: Type = ELF::R_X86_64_8; break; } } } else { if (IsPCRel) { switch (Modifier) { default: llvm_unreachable("Unimplemented"); case MCSymbolRefExpr::VK_None: Type = ELF::R_386_PC32; break; case MCSymbolRefExpr::VK_PLT: Type = ELF::R_386_PLT32; break; } } else { switch ((unsigned)Fixup.getKind()) { default: llvm_unreachable("invalid fixup kind!"); case X86::reloc_global_offset_table: Type = ELF::R_386_GOTPC; break; // FIXME: Should we avoid selecting reloc_signed_4byte in 32 bit mode // instead? case X86::reloc_signed_4byte: case FK_PCRel_4: case FK_Data_4: switch (Modifier) { default: llvm_unreachable("Unimplemented"); case MCSymbolRefExpr::VK_None: Type = ELF::R_386_32; break; case MCSymbolRefExpr::VK_GOT: Type = ELF::R_386_GOT32; break; case MCSymbolRefExpr::VK_GOTOFF: Type = ELF::R_386_GOTOFF; break; case MCSymbolRefExpr::VK_TLSGD: Type = ELF::R_386_TLS_GD; break; case MCSymbolRefExpr::VK_TPOFF: Type = ELF::R_386_TLS_LE_32; break; case MCSymbolRefExpr::VK_INDNTPOFF: Type = ELF::R_386_TLS_IE; break; case MCSymbolRefExpr::VK_NTPOFF: Type = ELF::R_386_TLS_LE; break; case MCSymbolRefExpr::VK_GOTNTPOFF: Type = ELF::R_386_TLS_GOTIE; break; case MCSymbolRefExpr::VK_TLSLDM: Type = ELF::R_386_TLS_LDM; break; case MCSymbolRefExpr::VK_DTPOFF: Type = ELF::R_386_TLS_LDO_32; break; } break; case FK_Data_2: Type = ELF::R_386_16; break; case FK_PCRel_1: case FK_Data_1: Type = ELF::R_386_8; break; } } } if (RelocNeedsGOT(Modifier)) NeedsGOT = true; return Type; }