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
20namespace lld::macho {
21LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
22
23class Symbol;
24class InputSection;
25
26enum 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
46struct RelocAttrs {
47 llvm::StringRef name;
48 RelocAttrBits bits;
49 bool hasAttr(RelocAttrBits b) const { return (bits & b) == b; }
50};
51
52struct 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
78bool 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 */
85void reportRangeError(void *loc, const Reloc &, const llvm::Twine &v,
86 uint8_t bits, int64_t min, uint64_t max);
87
88struct SymbolDiagnostic {
89 const Symbol *symbol;
90 llvm::StringRef reason;
91};
92
93void reportRangeError(void *loc, SymbolDiagnostic, const llvm::Twine &v,
94 uint8_t bits, int64_t min, uint64_t max);
95
96template <typename Diagnostic>
97inline void checkInt(void *loc, Diagnostic d, int64_t v, int bits) {
98 if (v != llvm::SignExtend64(X: v, B: bits))
99 reportRangeError(loc, d, llvm::Twine(v), bits, llvm::minIntN(N: bits),
100 llvm::maxIntN(N: bits));
101}
102
103template <typename Diagnostic>
104inline 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(N: bits));
107}
108
109inline void writeAddress(uint8_t *loc, uint64_t addr, uint8_t length) {
110 switch (length) {
111 case 2:
112 llvm::support::endian::write32le(P: loc, V: addr);
113 break;
114 case 3:
115 llvm::support::endian::write64le(P: loc, V: addr);
116 break;
117 default:
118 llvm_unreachable("invalid r_length");
119 }
120}
121
122InputSection *offsetToInputSection(uint64_t *);
123
124extern const RelocAttrs invalidRelocAttrs;
125
126} // namespace lld::Macho
127
128#endif
129