1 //===- Target.cpp ---------------------------------------------------------===// 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 // Machine-specific things, such as applying relocations, creation of 10 // GOT or PLT entries, etc., are handled in this file. 11 // 12 // Refer the ELF spec for the single letter variables, S, A or P, used 13 // in this file. 14 // 15 // Some functions defined in this file has "relaxTls" as part of their names. 16 // They do peephole optimization for TLS variables by rewriting instructions. 17 // They are not part of the ABI but optional optimization, so you can skip 18 // them if you are not interested in how TLS variables are optimized. 19 // See the following paper for the details. 20 // 21 // Ulrich Drepper, ELF Handling For Thread-Local Storage 22 // http://www.akkadia.org/drepper/tls.pdf 23 // 24 //===----------------------------------------------------------------------===// 25 26 #include "Target.h" 27 #include "InputFiles.h" 28 #include "OutputSections.h" 29 #include "SymbolTable.h" 30 #include "Symbols.h" 31 #include "lld/Common/ErrorHandler.h" 32 #include "llvm/Object/ELF.h" 33 34 using namespace llvm; 35 using namespace llvm::object; 36 using namespace llvm::ELF; 37 38 namespace lld { 39 std::string toString(elf::RelType type) { 40 StringRef s = getELFRelocationTypeName(elf::config->emachine, type); 41 if (s == "Unknown") 42 return ("Unknown (" + Twine(type) + ")").str(); 43 return s; 44 } 45 46 namespace elf { 47 const TargetInfo *target; 48 49 TargetInfo *getTarget() { 50 switch (config->emachine) { 51 case EM_386: 52 case EM_IAMCU: 53 return getX86TargetInfo(); 54 case EM_AARCH64: 55 return getAArch64TargetInfo(); 56 case EM_AMDGPU: 57 return getAMDGPUTargetInfo(); 58 case EM_ARM: 59 return getARMTargetInfo(); 60 case EM_AVR: 61 return getAVRTargetInfo(); 62 case EM_HEXAGON: 63 return getHexagonTargetInfo(); 64 case EM_MIPS: 65 switch (config->ekind) { 66 case ELF32LEKind: 67 return getMipsTargetInfo<ELF32LE>(); 68 case ELF32BEKind: 69 return getMipsTargetInfo<ELF32BE>(); 70 case ELF64LEKind: 71 return getMipsTargetInfo<ELF64LE>(); 72 case ELF64BEKind: 73 return getMipsTargetInfo<ELF64BE>(); 74 default: 75 llvm_unreachable("unsupported MIPS target"); 76 } 77 case EM_MSP430: 78 return getMSP430TargetInfo(); 79 case EM_PPC: 80 return getPPCTargetInfo(); 81 case EM_PPC64: 82 return getPPC64TargetInfo(); 83 case EM_RISCV: 84 return getRISCVTargetInfo(); 85 case EM_SPARCV9: 86 return getSPARCV9TargetInfo(); 87 case EM_X86_64: 88 return getX86_64TargetInfo(); 89 } 90 llvm_unreachable("unknown target machine"); 91 } 92 93 template <class ELFT> static ErrorPlace getErrPlace(const uint8_t *loc) { 94 for (InputSectionBase *d : inputSections) { 95 auto *isec = cast<InputSection>(d); 96 if (!isec->getParent()) 97 continue; 98 99 const uint8_t *isecLoc = 100 Out::bufferStart 101 ? (Out::bufferStart + isec->getParent()->offset + isec->outSecOff) 102 : isec->data().data(); 103 if (isecLoc <= loc && loc < isecLoc + isec->getSize()) 104 return {isec, isec->template getLocation<ELFT>(loc - isecLoc) + ": "}; 105 } 106 return {}; 107 } 108 109 ErrorPlace getErrorPlace(const uint8_t *loc) { 110 switch (config->ekind) { 111 case ELF32LEKind: 112 return getErrPlace<ELF32LE>(loc); 113 case ELF32BEKind: 114 return getErrPlace<ELF32BE>(loc); 115 case ELF64LEKind: 116 return getErrPlace<ELF64LE>(loc); 117 case ELF64BEKind: 118 return getErrPlace<ELF64BE>(loc); 119 default: 120 llvm_unreachable("unknown ELF type"); 121 } 122 } 123 124 TargetInfo::~TargetInfo() {} 125 126 int64_t TargetInfo::getImplicitAddend(const uint8_t *buf, RelType type) const { 127 return 0; 128 } 129 130 bool TargetInfo::usesOnlyLowPageBits(RelType type) const { return false; } 131 132 bool TargetInfo::needsThunk(RelExpr expr, RelType type, const InputFile *file, 133 uint64_t branchAddr, const Symbol &s, 134 int64_t a) const { 135 return false; 136 } 137 138 bool TargetInfo::adjustPrologueForCrossSplitStack(uint8_t *loc, uint8_t *end, 139 uint8_t stOther) const { 140 llvm_unreachable("Target doesn't support split stacks."); 141 } 142 143 bool TargetInfo::inBranchRange(RelType type, uint64_t src, uint64_t dst) const { 144 return true; 145 } 146 147 void TargetInfo::writeIgotPlt(uint8_t *buf, const Symbol &s) const { 148 writeGotPlt(buf, s); 149 } 150 151 RelExpr TargetInfo::adjustRelaxExpr(RelType type, const uint8_t *data, 152 RelExpr expr) const { 153 return expr; 154 } 155 156 void TargetInfo::relaxGot(uint8_t *loc, RelType type, uint64_t val) const { 157 llvm_unreachable("Should not have claimed to be relaxable"); 158 } 159 160 void TargetInfo::relaxTlsGdToLe(uint8_t *loc, RelType type, 161 uint64_t val) const { 162 llvm_unreachable("Should not have claimed to be relaxable"); 163 } 164 165 void TargetInfo::relaxTlsGdToIe(uint8_t *loc, RelType type, 166 uint64_t val) const { 167 llvm_unreachable("Should not have claimed to be relaxable"); 168 } 169 170 void TargetInfo::relaxTlsIeToLe(uint8_t *loc, RelType type, 171 uint64_t val) const { 172 llvm_unreachable("Should not have claimed to be relaxable"); 173 } 174 175 void TargetInfo::relaxTlsLdToLe(uint8_t *loc, RelType type, 176 uint64_t val) const { 177 llvm_unreachable("Should not have claimed to be relaxable"); 178 } 179 180 uint64_t TargetInfo::getImageBase() const { 181 // Use -image-base if set. Fall back to the target default if not. 182 if (config->imageBase) 183 return *config->imageBase; 184 return config->isPic ? 0 : defaultImageBase; 185 } 186 187 } // namespace elf 188 } // namespace lld 189