1 //===- Relocations.h -------------------------------------------*- 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 LLD_ELF_RELOCATIONS_H 10 #define LLD_ELF_RELOCATIONS_H 11 12 #include "lld/Common/LLVM.h" 13 #include "llvm/ADT/DenseMap.h" 14 #include <map> 15 #include <vector> 16 17 namespace lld { 18 namespace elf { 19 class Symbol; 20 class InputSection; 21 class InputSectionBase; 22 class OutputSection; 23 class SectionBase; 24 25 // Represents a relocation type, such as R_X86_64_PC32 or R_ARM_THM_CALL. 26 using RelType = uint32_t; 27 28 // List of target-independent relocation types. Relocations read 29 // from files are converted to these types so that the main code 30 // doesn't have to know about architecture-specific details. 31 enum RelExpr { 32 R_ABS, 33 R_ADDEND, 34 R_DTPREL, 35 R_GOT, 36 R_GOT_OFF, 37 R_GOT_PC, 38 R_GOTONLY_PC, 39 R_GOTPLTONLY_PC, 40 R_GOTPLT, 41 R_GOTPLTREL, 42 R_GOTREL, 43 R_HINT, 44 R_NEG_TLS, 45 R_NONE, 46 R_PC, 47 R_PLT, 48 R_PLT_PC, 49 R_RELAX_GOT_PC, 50 R_RELAX_GOT_PC_NOPIC, 51 R_RELAX_TLS_GD_TO_IE, 52 R_RELAX_TLS_GD_TO_IE_ABS, 53 R_RELAX_TLS_GD_TO_IE_GOT_OFF, 54 R_RELAX_TLS_GD_TO_IE_GOTPLT, 55 R_RELAX_TLS_GD_TO_LE, 56 R_RELAX_TLS_GD_TO_LE_NEG, 57 R_RELAX_TLS_IE_TO_LE, 58 R_RELAX_TLS_LD_TO_LE, 59 R_RELAX_TLS_LD_TO_LE_ABS, 60 R_SIZE, 61 R_TLS, 62 R_TLSDESC, 63 R_TLSDESC_CALL, 64 R_TLSDESC_PC, 65 R_TLSGD_GOT, 66 R_TLSGD_GOTPLT, 67 R_TLSGD_PC, 68 R_TLSIE_HINT, 69 R_TLSLD_GOT, 70 R_TLSLD_GOTPLT, 71 R_TLSLD_GOT_OFF, 72 R_TLSLD_HINT, 73 R_TLSLD_PC, 74 75 // The following is abstract relocation types used for only one target. 76 // 77 // Even though RelExpr is intended to be a target-neutral representation 78 // of a relocation type, there are some relocations whose semantics are 79 // unique to a target. Such relocation are marked with R_<TARGET_NAME>. 80 R_AARCH64_GOT_PAGE_PC, 81 R_AARCH64_PAGE_PC, 82 R_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC, 83 R_AARCH64_TLSDESC_PAGE, 84 R_ARM_SBREL, 85 R_HEXAGON_GOT, 86 R_MIPS_GOTREL, 87 R_MIPS_GOT_GP, 88 R_MIPS_GOT_GP_PC, 89 R_MIPS_GOT_LOCAL_PAGE, 90 R_MIPS_GOT_OFF, 91 R_MIPS_GOT_OFF32, 92 R_MIPS_TLSGD, 93 R_MIPS_TLSLD, 94 R_PPC32_PLTREL, 95 R_PPC64_CALL, 96 R_PPC64_CALL_PLT, 97 R_PPC64_RELAX_TOC, 98 R_PPC64_TOCBASE, 99 R_RISCV_ADD, 100 R_RISCV_PC_INDIRECT, 101 }; 102 103 // Architecture-neutral representation of relocation. 104 struct Relocation { 105 RelExpr expr; 106 RelType type; 107 uint64_t offset; 108 int64_t addend; 109 Symbol *sym; 110 }; 111 112 // This function writes undefined symbol diagnostics to an internal buffer. 113 // Call reportUndefinedSymbols() after calling scanRelocations() to emit 114 // the diagnostics. 115 template <class ELFT> void scanRelocations(InputSectionBase &); 116 117 template <class ELFT> void reportUndefinedSymbols(); 118 119 void addIRelativeRelocs(); 120 121 class ThunkSection; 122 class Thunk; 123 struct InputSectionDescription; 124 125 class ThunkCreator { 126 public: 127 // Return true if Thunks have been added to OutputSections 128 bool createThunks(ArrayRef<OutputSection *> outputSections); 129 130 // The number of completed passes of createThunks this permits us 131 // to do one time initialization on Pass 0 and put a limit on the 132 // number of times it can be called to prevent infinite loops. 133 uint32_t pass = 0; 134 135 private: 136 void mergeThunks(ArrayRef<OutputSection *> outputSections); 137 138 ThunkSection *getISDThunkSec(OutputSection *os, InputSection *isec, 139 InputSectionDescription *isd, uint32_t type, 140 uint64_t src); 141 142 ThunkSection *getISThunkSec(InputSection *isec); 143 144 void createInitialThunkSections(ArrayRef<OutputSection *> outputSections); 145 146 std::pair<Thunk *, bool> getThunk(InputSection *isec, Relocation &rel, 147 uint64_t src); 148 149 ThunkSection *addThunkSection(OutputSection *os, InputSectionDescription *, 150 uint64_t off); 151 152 bool normalizeExistingThunk(Relocation &rel, uint64_t src); 153 154 // Record all the available Thunks for a Symbol 155 llvm::DenseMap<std::pair<SectionBase *, uint64_t>, std::vector<Thunk *>> 156 thunkedSymbolsBySection; 157 llvm::DenseMap<Symbol *, std::vector<Thunk *>> thunkedSymbols; 158 159 // Find a Thunk from the Thunks symbol definition, we can use this to find 160 // the Thunk from a relocation to the Thunks symbol definition. 161 llvm::DenseMap<Symbol *, Thunk *> thunks; 162 163 // Track InputSections that have an inline ThunkSection placed in front 164 // an inline ThunkSection may have control fall through to the section below 165 // so we need to make sure that there is only one of them. 166 // The Mips LA25 Thunk is an example of an inline ThunkSection. 167 llvm::DenseMap<InputSection *, ThunkSection *> thunkedSections; 168 }; 169 170 // Return a int64_t to make sure we get the sign extension out of the way as 171 // early as possible. 172 template <class ELFT> 173 static inline int64_t getAddend(const typename ELFT::Rel &rel) { 174 return 0; 175 } 176 template <class ELFT> 177 static inline int64_t getAddend(const typename ELFT::Rela &rel) { 178 return rel.r_addend; 179 } 180 } // namespace elf 181 } // namespace lld 182 183 #endif 184