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_MACHO_RELOCATIONS_H 10 #define LLD_MACHO_RELOCATIONS_H 11 12 #include "llvm/ADT/BitmaskEnum.h" 13 #include "llvm/ADT/PointerUnion.h" 14 #include "llvm/BinaryFormat/MachO.h" 15 #include "llvm/Support/Endian.h" 16 17 #include <cstddef> 18 #include <cstdint> 19 20 namespace lld { 21 namespace macho { 22 LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE(); 23 24 class Symbol; 25 class InputSection; 26 27 enum class RelocAttrBits { 28 _0 = 0, // invalid 29 PCREL = 1 << 0, // Value is PC-relative offset 30 ABSOLUTE = 1 << 1, // Value is an absolute address or fixed offset 31 BYTE4 = 1 << 2, // 4 byte datum 32 BYTE8 = 1 << 3, // 8 byte datum 33 EXTERN = 1 << 4, // Can have an external symbol 34 LOCAL = 1 << 5, // Can have a local symbol 35 ADDEND = 1 << 6, // *_ADDEND paired prefix reloc 36 SUBTRAHEND = 1 << 7, // *_SUBTRACTOR paired prefix reloc 37 BRANCH = 1 << 8, // Value is branch target 38 GOT = 1 << 9, // References a symbol in the Global Offset Table 39 TLV = 1 << 10, // References a thread-local symbol 40 LOAD = 1 << 11, // Relaxable indirect load 41 POINTER = 1 << 12, // Non-relaxable indirect load (pointer is taken) 42 UNSIGNED = 1 << 13, // *_UNSIGNED relocs 43 LLVM_MARK_AS_BITMASK_ENUM(/*LargestValue*/ (1 << 14) - 1), 44 }; 45 // Note: SUBTRACTOR always pairs with UNSIGNED (a delta between two symbols). 46 47 struct RelocAttrs { 48 llvm::StringRef name; 49 RelocAttrBits bits; 50 bool hasAttr(RelocAttrBits b) const { return (bits & b) == b; } 51 }; 52 53 struct Reloc { 54 uint8_t type = llvm::MachO::GENERIC_RELOC_INVALID; 55 bool pcrel = false; 56 uint8_t length = 0; 57 // The offset from the start of the subsection that this relocation belongs 58 // to. 59 uint32_t offset = 0; 60 // Adding this offset to the address of the referent symbol or subsection 61 // gives the destination that this relocation refers to. 62 int64_t addend = 0; 63 llvm::PointerUnion<Symbol *, InputSection *> referent = nullptr; 64 65 Reloc() = default; 66 67 Reloc(uint8_t type, bool pcrel, uint8_t length, uint32_t offset, 68 int64_t addend, llvm::PointerUnion<Symbol *, InputSection *> referent) 69 : type(type), pcrel(pcrel), length(length), offset(offset), 70 addend(addend), referent(referent) {} 71 }; 72 73 struct OptimizationHint { 74 // Offset of the first address within the containing InputSection. 75 uint64_t offset0; 76 // Offset of the other addresses relative to the first one. 77 int16_t delta[2]; 78 uint8_t type; 79 }; 80 81 bool validateSymbolRelocation(const Symbol *, const InputSection *, 82 const Reloc &); 83 84 /* 85 * v: The value the relocation is attempting to encode 86 * bits: The number of bits actually available to encode this relocation 87 */ 88 void reportRangeError(void *loc, const Reloc &, const llvm::Twine &v, 89 uint8_t bits, int64_t min, uint64_t max); 90 91 struct SymbolDiagnostic { 92 const Symbol *symbol; 93 llvm::StringRef reason; 94 }; 95 96 void reportRangeError(void *loc, SymbolDiagnostic, const llvm::Twine &v, 97 uint8_t bits, int64_t min, uint64_t max); 98 99 template <typename Diagnostic> 100 inline void checkInt(void *loc, Diagnostic d, int64_t v, int bits) { 101 if (v != llvm::SignExtend64(v, bits)) 102 reportRangeError(loc, d, llvm::Twine(v), bits, llvm::minIntN(bits), 103 llvm::maxIntN(bits)); 104 } 105 106 template <typename Diagnostic> 107 inline void checkUInt(void *loc, Diagnostic d, uint64_t v, int bits) { 108 if ((v >> bits) != 0) 109 reportRangeError(loc, d, llvm::Twine(v), bits, 0, llvm::maxUIntN(bits)); 110 } 111 112 inline void writeAddress(uint8_t *loc, uint64_t addr, uint8_t length) { 113 switch (length) { 114 case 2: 115 llvm::support::endian::write32le(loc, addr); 116 break; 117 case 3: 118 llvm::support::endian::write64le(loc, addr); 119 break; 120 default: 121 llvm_unreachable("invalid r_length"); 122 } 123 } 124 125 extern const RelocAttrs invalidRelocAttrs; 126 127 } // namespace macho 128 } // namespace lld 129 130 #endif 131