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
74bool 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 */
81void reportRangeError(void *loc, const Reloc &, const llvm::Twine &v,
82                      uint8_t bits, int64_t min, uint64_t max);
83
84struct SymbolDiagnostic {
85  const Symbol *symbol;
86  llvm::StringRef reason;
87};
88
89void reportRangeError(void *loc, SymbolDiagnostic, const llvm::Twine &v,
90                      uint8_t bits, int64_t min, uint64_t max);
91
92template <typename Diagnostic>
93inline 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
99template <typename Diagnostic>
100inline 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
105inline 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
118InputSection *offsetToInputSection(uint64_t *);
119
120extern const RelocAttrs invalidRelocAttrs;
121
122} // namespace lld::Macho
123
124#endif
125