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Diffstat (limited to 'contrib/llvm/lib/MC/ELFObjectWriter.cpp')
| -rw-r--r-- | contrib/llvm/lib/MC/ELFObjectWriter.cpp | 1841 |
1 files changed, 1841 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..8a00a16 --- /dev/null +++ b/contrib/llvm/lib/MC/ELFObjectWriter.cpp @@ -0,0 +1,1841 @@ +//===- 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 <vector> +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<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; + + // 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<const MCSectionELF*, uint32_t> 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<const MCSectionELF*, const MCSymbol*> GroupMapTy; + // Map from a signature symbol to the group section + typedef DenseMap<const MCSymbol*, const MCSectionELF*> 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 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<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) + 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<const MCSectionELF&>(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<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 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<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) + 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<uint64_t> 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<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++); +} + +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<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); + + 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<ELFRelocationEntry> &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<uint64_t> SecStringMap; + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionELF &Section = + static_cast<const MCSectionELF&>(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'; + } +} + +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<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; + } + + // 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<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); + 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<MCDataFragment>(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<MCDataFragment>(F).getContents().str()); + } +} + +void ELFObjectWriter::WriteObject(MCAssembler &Asm, + const MCAsmLayout &Layout) { + GroupMapTy GroupMap; + RevGroupMapTy RevGroupMap; + CreateIndexedSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap, + RevGroupMap); + + SectionIndexMapTy SectionIndexMap; + + ComputeIndexMap(Asm, SectionIndexMap); + + // Compute symbol table information. + ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap); + + CreateMetadataSections(const_cast<MCAssembler&>(Asm), + const_cast<MCAsmLayout&>(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<const MCSectionELF*> Sections; + Sections.resize(NumSections); + + 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] = 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<const MCSection*, uint64_t> 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<bool>(Symbol.getName()) + .Case("_MergedGlobals", true) + .Default(false); + } else { + EmitThisSym = StringSwitch<bool>(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; +} |
