1 //===- llvm/MC/MCELFObjectWriter.h - ELF Object Writer ----------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLVM_MC_MCELFOBJECTWRITER_H 10 #define LLVM_MC_MCELFOBJECTWRITER_H 11 12 #include "llvm/ADT/Triple.h" 13 #include "llvm/BinaryFormat/ELF.h" 14 #include "llvm/MC/MCObjectWriter.h" 15 #include "llvm/MC/MCSectionELF.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 uint8_t ABIVersion; 57 const uint16_t EMachine; 58 const unsigned HasRelocationAddend : 1; 59 const unsigned Is64Bit : 1; 60 61 protected: 62 MCELFObjectTargetWriter(bool Is64Bit_, uint8_t OSABI_, uint16_t EMachine_, 63 bool HasRelocationAddend_, uint8_t ABIVersion_ = 0); 64 65 public: 66 virtual ~MCELFObjectTargetWriter() = default; 67 getFormat()68 virtual Triple::ObjectFormatType getFormat() const { return Triple::ELF; } classof(const MCObjectTargetWriter * W)69 static bool classof(const MCObjectTargetWriter *W) { 70 return W->getFormat() == Triple::ELF; 71 } 72 getOSABI(Triple::OSType OSType)73 static uint8_t getOSABI(Triple::OSType OSType) { 74 switch (OSType) { 75 case Triple::CloudABI: 76 return ELF::ELFOSABI_CLOUDABI; 77 case Triple::HermitCore: 78 return ELF::ELFOSABI_STANDALONE; 79 case Triple::PS4: 80 case Triple::FreeBSD: 81 return ELF::ELFOSABI_FREEBSD; 82 default: 83 return ELF::ELFOSABI_NONE; 84 } 85 } 86 87 virtual unsigned getRelocType(MCContext &Ctx, const MCValue &Target, 88 const MCFixup &Fixup, bool IsPCRel) const = 0; 89 90 virtual bool needsRelocateWithSymbol(const MCSymbol &Sym, 91 unsigned Type) const; 92 93 virtual void sortRelocs(const MCAssembler &Asm, 94 std::vector<ELFRelocationEntry> &Relocs); 95 96 virtual void addTargetSectionFlags(MCContext &Ctx, MCSectionELF &Sec); 97 98 /// \name Accessors 99 /// @{ getOSABI()100 uint8_t getOSABI() const { return OSABI; } getABIVersion()101 uint8_t getABIVersion() const { return ABIVersion; } getEMachine()102 uint16_t getEMachine() const { return EMachine; } hasRelocationAddend()103 bool hasRelocationAddend() const { return HasRelocationAddend; } is64Bit()104 bool is64Bit() const { return Is64Bit; } 105 /// @} 106 107 // Instead of changing everyone's API we pack the N64 Type fields 108 // into the existing 32 bit data unsigned. 109 #define R_TYPE_SHIFT 0 110 #define R_TYPE_MASK 0xffffff00 111 #define R_TYPE2_SHIFT 8 112 #define R_TYPE2_MASK 0xffff00ff 113 #define R_TYPE3_SHIFT 16 114 #define R_TYPE3_MASK 0xff00ffff 115 #define R_SSYM_SHIFT 24 116 #define R_SSYM_MASK 0x00ffffff 117 118 // N64 relocation type accessors getRType(uint32_t Type)119 uint8_t getRType(uint32_t Type) const { 120 return (unsigned)((Type >> R_TYPE_SHIFT) & 0xff); 121 } getRType2(uint32_t Type)122 uint8_t getRType2(uint32_t Type) const { 123 return (unsigned)((Type >> R_TYPE2_SHIFT) & 0xff); 124 } getRType3(uint32_t Type)125 uint8_t getRType3(uint32_t Type) const { 126 return (unsigned)((Type >> R_TYPE3_SHIFT) & 0xff); 127 } getRSsym(uint32_t Type)128 uint8_t getRSsym(uint32_t Type) const { 129 return (unsigned)((Type >> R_SSYM_SHIFT) & 0xff); 130 } 131 132 // N64 relocation type setting setRType(unsigned Value,unsigned Type)133 unsigned setRType(unsigned Value, unsigned Type) const { 134 return ((Type & R_TYPE_MASK) | ((Value & 0xff) << R_TYPE_SHIFT)); 135 } setRType2(unsigned Value,unsigned Type)136 unsigned setRType2(unsigned Value, unsigned Type) const { 137 return (Type & R_TYPE2_MASK) | ((Value & 0xff) << R_TYPE2_SHIFT); 138 } setRType3(unsigned Value,unsigned Type)139 unsigned setRType3(unsigned Value, unsigned Type) const { 140 return (Type & R_TYPE3_MASK) | ((Value & 0xff) << R_TYPE3_SHIFT); 141 } setRSsym(unsigned Value,unsigned Type)142 unsigned setRSsym(unsigned Value, unsigned Type) const { 143 return (Type & R_SSYM_MASK) | ((Value & 0xff) << R_SSYM_SHIFT); 144 } 145 }; 146 147 /// Construct a new ELF writer instance. 148 /// 149 /// \param MOTW - The target specific ELF writer subclass. 150 /// \param OS - The stream to write to. 151 /// \returns The constructed object writer. 152 std::unique_ptr<MCObjectWriter> 153 createELFObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW, 154 raw_pwrite_stream &OS, bool IsLittleEndian); 155 156 std::unique_ptr<MCObjectWriter> 157 createELFDwoObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW, 158 raw_pwrite_stream &OS, raw_pwrite_stream &DwoOS, 159 bool IsLittleEndian); 160 161 } // end namespace llvm 162 163 #endif // LLVM_MC_MCELFOBJECTWRITER_H 164