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 66 bool validateSymbolRelocation(const Symbol *, const InputSection *, 67 const Reloc &); 68 69 /* 70 * v: The value the relocation is attempting to encode 71 * bits: The number of bits actually available to encode this relocation 72 */ 73 void reportRangeError(const Reloc &, const llvm::Twine &v, uint8_t bits, 74 int64_t min, uint64_t max); 75 76 struct SymbolDiagnostic { 77 const Symbol *symbol; 78 llvm::StringRef reason; 79 }; 80 81 void reportRangeError(SymbolDiagnostic, const llvm::Twine &v, uint8_t bits, 82 int64_t min, uint64_t max); 83 84 template <typename Diagnostic> 85 inline void checkInt(Diagnostic d, int64_t v, int bits) { 86 if (v != llvm::SignExtend64(v, bits)) 87 reportRangeError(d, llvm::Twine(v), bits, llvm::minIntN(bits), 88 llvm::maxIntN(bits)); 89 } 90 91 template <typename Diagnostic> 92 inline void checkUInt(Diagnostic d, uint64_t v, int bits) { 93 if ((v >> bits) != 0) 94 reportRangeError(d, llvm::Twine(v), bits, 0, llvm::maxUIntN(bits)); 95 } 96 97 inline void writeAddress(uint8_t *loc, uint64_t addr, uint8_t length) { 98 switch (length) { 99 case 2: 100 llvm::support::endian::write32le(loc, addr); 101 break; 102 case 3: 103 llvm::support::endian::write64le(loc, addr); 104 break; 105 default: 106 llvm_unreachable("invalid r_length"); 107 } 108 } 109 110 extern const RelocAttrs invalidRelocAttrs; 111 112 } // namespace macho 113 } // namespace lld 114 115 #endif 116