1 //===- llvm/MC/MCELFObjectWriter.h - ELF Object Writer ----------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef LLVM_MC_MCELFOBJECTWRITER_H 11 #define LLVM_MC_MCELFOBJECTWRITER_H 12 13 #include "llvm/ADT/Triple.h" 14 #include "llvm/BinaryFormat/ELF.h" 15 #include "llvm/MC/MCObjectWriter.h" 16 #include "llvm/Support/Casting.h" 17 #include "llvm/Support/raw_ostream.h" 18 #include <cstdint> 19 #include <vector> 20 21 namespace llvm { 22 23 class MCAssembler; 24 class MCContext; 25 class MCFixup; 26 class MCObjectWriter; 27 class MCSymbol; 28 class MCSymbolELF; 29 class MCValue; 30 31 struct ELFRelocationEntry { 32 uint64_t Offset; // Where is the relocation. 33 const MCSymbolELF *Symbol; // The symbol to relocate with. 34 unsigned Type; // The type of the relocation. 35 uint64_t Addend; // The addend to use. 36 const MCSymbolELF *OriginalSymbol; // The original value of Symbol if we changed it. 37 uint64_t OriginalAddend; // The original value of addend. 38 ELFRelocationEntryELFRelocationEntry39 ELFRelocationEntry(uint64_t Offset, const MCSymbolELF *Symbol, unsigned Type, 40 uint64_t Addend, const MCSymbolELF *OriginalSymbol, 41 uint64_t OriginalAddend) 42 : Offset(Offset), Symbol(Symbol), Type(Type), Addend(Addend), 43 OriginalSymbol(OriginalSymbol), OriginalAddend(OriginalAddend) {} 44 printELFRelocationEntry45 void print(raw_ostream &Out) const { 46 Out << "Off=" << Offset << ", Sym=" << Symbol << ", Type=" << Type 47 << ", Addend=" << Addend << ", OriginalSymbol=" << OriginalSymbol 48 << ", OriginalAddend=" << OriginalAddend; 49 } 50 dumpELFRelocationEntry51 void dump() const { print(errs()); } 52 }; 53 54 class MCELFObjectTargetWriter : public MCObjectTargetWriter { 55 const uint8_t OSABI; 56 const uint16_t EMachine; 57 const unsigned HasRelocationAddend : 1; 58 const unsigned Is64Bit : 1; 59 60 protected: 61 MCELFObjectTargetWriter(bool Is64Bit_, uint8_t OSABI_, uint16_t EMachine_, 62 bool HasRelocationAddend); 63 64 public: 65 virtual ~MCELFObjectTargetWriter() = default; 66 getFormat()67 virtual Triple::ObjectFormatType getFormat() const { return Triple::ELF; } classof(const MCObjectTargetWriter * W)68 static bool classof(const MCObjectTargetWriter *W) { 69 return W->getFormat() == Triple::ELF; 70 } 71 getOSABI(Triple::OSType OSType)72 static uint8_t getOSABI(Triple::OSType OSType) { 73 switch (OSType) { 74 case Triple::CloudABI: 75 return ELF::ELFOSABI_CLOUDABI; 76 case Triple::PS4: 77 case Triple::FreeBSD: 78 return ELF::ELFOSABI_FREEBSD; 79 default: 80 return ELF::ELFOSABI_NONE; 81 } 82 } 83 84 virtual unsigned getRelocType(MCContext &Ctx, const MCValue &Target, 85 const MCFixup &Fixup, bool IsPCRel) const = 0; 86 87 virtual bool needsRelocateWithSymbol(const MCSymbol &Sym, 88 unsigned Type) const; 89 90 virtual void sortRelocs(const MCAssembler &Asm, 91 std::vector<ELFRelocationEntry> &Relocs); 92 93 /// \name Accessors 94 /// @{ getOSABI()95 uint8_t getOSABI() const { return OSABI; } getEMachine()96 uint16_t getEMachine() const { return EMachine; } hasRelocationAddend()97 bool hasRelocationAddend() const { return HasRelocationAddend; } is64Bit()98 bool is64Bit() const { return Is64Bit; } 99 /// @} 100 101 // Instead of changing everyone's API we pack the N64 Type fields 102 // into the existing 32 bit data unsigned. 103 #define R_TYPE_SHIFT 0 104 #define R_TYPE_MASK 0xffffff00 105 #define R_TYPE2_SHIFT 8 106 #define R_TYPE2_MASK 0xffff00ff 107 #define R_TYPE3_SHIFT 16 108 #define R_TYPE3_MASK 0xff00ffff 109 #define R_SSYM_SHIFT 24 110 #define R_SSYM_MASK 0x00ffffff 111 112 // N64 relocation type accessors getRType(uint32_t Type)113 uint8_t getRType(uint32_t Type) const { 114 return (unsigned)((Type >> R_TYPE_SHIFT) & 0xff); 115 } getRType2(uint32_t Type)116 uint8_t getRType2(uint32_t Type) const { 117 return (unsigned)((Type >> R_TYPE2_SHIFT) & 0xff); 118 } getRType3(uint32_t Type)119 uint8_t getRType3(uint32_t Type) const { 120 return (unsigned)((Type >> R_TYPE3_SHIFT) & 0xff); 121 } getRSsym(uint32_t Type)122 uint8_t getRSsym(uint32_t Type) const { 123 return (unsigned)((Type >> R_SSYM_SHIFT) & 0xff); 124 } 125 126 // N64 relocation type setting setRType(unsigned Value,unsigned Type)127 unsigned setRType(unsigned Value, unsigned Type) const { 128 return ((Type & R_TYPE_MASK) | ((Value & 0xff) << R_TYPE_SHIFT)); 129 } setRType2(unsigned Value,unsigned Type)130 unsigned setRType2(unsigned Value, unsigned Type) const { 131 return (Type & R_TYPE2_MASK) | ((Value & 0xff) << R_TYPE2_SHIFT); 132 } setRType3(unsigned Value,unsigned Type)133 unsigned setRType3(unsigned Value, unsigned Type) const { 134 return (Type & R_TYPE3_MASK) | ((Value & 0xff) << R_TYPE3_SHIFT); 135 } setRSsym(unsigned Value,unsigned Type)136 unsigned setRSsym(unsigned Value, unsigned Type) const { 137 return (Type & R_SSYM_MASK) | ((Value & 0xff) << R_SSYM_SHIFT); 138 } 139 }; 140 141 /// Construct a new ELF writer instance. 142 /// 143 /// \param MOTW - The target specific ELF writer subclass. 144 /// \param OS - The stream to write to. 145 /// \returns The constructed object writer. 146 std::unique_ptr<MCObjectWriter> 147 createELFObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW, 148 raw_pwrite_stream &OS, bool IsLittleEndian); 149 150 std::unique_ptr<MCObjectWriter> 151 createELFDwoObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW, 152 raw_pwrite_stream &OS, raw_pwrite_stream &DwoOS, 153 bool IsLittleEndian); 154 155 } // end namespace llvm 156 157 #endif // LLVM_MC_MCELFOBJECTWRITER_H 158