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 // Must point to an offset within a CStringInputSection or a 74 // ConcatInputSection. 75 llvm::StringRef getReferentString() const; 76 }; 77 78 bool validateSymbolRelocation(const Symbol *, const InputSection *, 79 const Reloc &); 80 81 /* 82 * v: The value the relocation is attempting to encode 83 * bits: The number of bits actually available to encode this relocation 84 */ 85 void reportRangeError(void *loc, const Reloc &, const llvm::Twine &v, 86 uint8_t bits, int64_t min, uint64_t max); 87 88 struct SymbolDiagnostic { 89 const Symbol *symbol; 90 llvm::StringRef reason; 91 }; 92 93 void reportRangeError(void *loc, SymbolDiagnostic, const llvm::Twine &v, 94 uint8_t bits, int64_t min, uint64_t max); 95 96 template <typename Diagnostic> 97 inline void checkInt(void *loc, Diagnostic d, int64_t v, int bits) { 98 if (v != llvm::SignExtend64(v, bits)) 99 reportRangeError(loc, d, llvm::Twine(v), bits, llvm::minIntN(bits), 100 llvm::maxIntN(bits)); 101 } 102 103 template <typename Diagnostic> 104 inline void checkUInt(void *loc, Diagnostic d, uint64_t v, int bits) { 105 if ((v >> bits) != 0) 106 reportRangeError(loc, d, llvm::Twine(v), bits, 0, llvm::maxUIntN(bits)); 107 } 108 109 inline void writeAddress(uint8_t *loc, uint64_t addr, uint8_t length) { 110 switch (length) { 111 case 2: 112 llvm::support::endian::write32le(loc, addr); 113 break; 114 case 3: 115 llvm::support::endian::write64le(loc, addr); 116 break; 117 default: 118 llvm_unreachable("invalid r_length"); 119 } 120 } 121 122 InputSection *offsetToInputSection(uint64_t *); 123 124 extern const RelocAttrs invalidRelocAttrs; 125 126 } // namespace lld::Macho 127 128 #endif 129