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 MCSymbol; 27 class MCSymbolELF; 28 class MCValue; 29 30 struct ELFRelocationEntry { 31 uint64_t Offset; // Where is the relocation. 32 const MCSymbolELF *Symbol; // The symbol to relocate with. 33 unsigned Type; // The type of the relocation. 34 uint64_t Addend; // The addend to use. 35 const MCSymbolELF *OriginalSymbol; // The original value of Symbol if we changed it. 36 uint64_t OriginalAddend; // The original value of addend. 37 ELFRelocationEntryELFRelocationEntry38 ELFRelocationEntry(uint64_t Offset, const MCSymbolELF *Symbol, unsigned Type, 39 uint64_t Addend, const MCSymbolELF *OriginalSymbol, 40 uint64_t OriginalAddend) 41 : Offset(Offset), Symbol(Symbol), Type(Type), Addend(Addend), 42 OriginalSymbol(OriginalSymbol), OriginalAddend(OriginalAddend) {} 43 printELFRelocationEntry44 void print(raw_ostream &Out) const { 45 Out << "Off=" << Offset << ", Sym=" << Symbol << ", Type=" << Type 46 << ", Addend=" << Addend << ", OriginalSymbol=" << OriginalSymbol 47 << ", OriginalAddend=" << OriginalAddend; 48 } 49 dumpELFRelocationEntry50 LLVM_DUMP_METHOD void dump() const { print(errs()); } 51 }; 52 53 class MCELFObjectTargetWriter : public MCObjectTargetWriter { 54 const uint8_t OSABI; 55 const uint8_t ABIVersion; 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_, uint8_t ABIVersion_ = 0); 63 64 public: 65 virtual ~MCELFObjectTargetWriter() = default; 66 getFormat()67 Triple::ObjectFormatType getFormat() const override { 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::HermitCore: 77 return ELF::ELFOSABI_STANDALONE; 78 case Triple::PS4: 79 case Triple::FreeBSD: 80 return ELF::ELFOSABI_FREEBSD; 81 default: 82 return ELF::ELFOSABI_NONE; 83 } 84 } 85 86 virtual unsigned getRelocType(MCContext &Ctx, const MCValue &Target, 87 const MCFixup &Fixup, bool IsPCRel) const = 0; 88 89 virtual bool needsRelocateWithSymbol(const MCSymbol &Sym, 90 unsigned Type) const; 91 92 virtual void sortRelocs(const MCAssembler &Asm, 93 std::vector<ELFRelocationEntry> &Relocs); 94 95 virtual void addTargetSectionFlags(MCContext &Ctx, MCSectionELF &Sec); 96 97 /// \name Accessors 98 /// @{ getOSABI()99 uint8_t getOSABI() const { return OSABI; } getABIVersion()100 uint8_t getABIVersion() const { return ABIVersion; } getEMachine()101 uint16_t getEMachine() const { return EMachine; } hasRelocationAddend()102 bool hasRelocationAddend() const { return HasRelocationAddend; } is64Bit()103 bool is64Bit() const { return Is64Bit; } 104 /// @} 105 106 // Instead of changing everyone's API we pack the N64 Type fields 107 // into the existing 32 bit data unsigned. 108 #define R_TYPE_SHIFT 0 109 #define R_TYPE_MASK 0xffffff00 110 #define R_TYPE2_SHIFT 8 111 #define R_TYPE2_MASK 0xffff00ff 112 #define R_TYPE3_SHIFT 16 113 #define R_TYPE3_MASK 0xff00ffff 114 #define R_SSYM_SHIFT 24 115 #define R_SSYM_MASK 0x00ffffff 116 117 // N64 relocation type accessors getRType(uint32_t Type)118 uint8_t getRType(uint32_t Type) const { 119 return (unsigned)((Type >> R_TYPE_SHIFT) & 0xff); 120 } getRType2(uint32_t Type)121 uint8_t getRType2(uint32_t Type) const { 122 return (unsigned)((Type >> R_TYPE2_SHIFT) & 0xff); 123 } getRType3(uint32_t Type)124 uint8_t getRType3(uint32_t Type) const { 125 return (unsigned)((Type >> R_TYPE3_SHIFT) & 0xff); 126 } getRSsym(uint32_t Type)127 uint8_t getRSsym(uint32_t Type) const { 128 return (unsigned)((Type >> R_SSYM_SHIFT) & 0xff); 129 } 130 131 // N64 relocation type setting setRTypes(unsigned Value1,unsigned Value2,unsigned Value3)132 static unsigned setRTypes(unsigned Value1, unsigned Value2, unsigned Value3) { 133 return ((Value1 & 0xff) << R_TYPE_SHIFT) | 134 ((Value2 & 0xff) << R_TYPE2_SHIFT) | 135 ((Value3 & 0xff) << R_TYPE3_SHIFT); 136 } setRSsym(unsigned Value,unsigned Type)137 unsigned setRSsym(unsigned Value, unsigned Type) const { 138 return (Type & R_SSYM_MASK) | ((Value & 0xff) << R_SSYM_SHIFT); 139 } 140 }; 141 142 /// Construct a new ELF writer instance. 143 /// 144 /// \param MOTW - The target specific ELF writer subclass. 145 /// \param OS - The stream to write to. 146 /// \returns The constructed object writer. 147 std::unique_ptr<MCObjectWriter> 148 createELFObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW, 149 raw_pwrite_stream &OS, bool IsLittleEndian); 150 151 std::unique_ptr<MCObjectWriter> 152 createELFDwoObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW, 153 raw_pwrite_stream &OS, raw_pwrite_stream &DwoOS, 154 bool IsLittleEndian); 155 156 } // end namespace llvm 157 158 #endif // LLVM_MC_MCELFOBJECTWRITER_H 159