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