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1 //===- Relocations.h --------------------------------------------*- C++ -*-===//
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2 //
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3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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4 // See https://llvm.org/LICENSE.txt for license information.
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5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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6 //
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7 //===----------------------------------------------------------------------===//
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8
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9 #ifndef LLD_MACHO_RELOCATIONS_H
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10 #define LLD_MACHO_RELOCATIONS_H
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11
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12 #include "llvm/ADT/BitmaskEnum.h"
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13 #include "llvm/ADT/PointerUnion.h"
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14 #include "llvm/BinaryFormat/MachO.h"
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15 #include "llvm/Support/Endian.h"
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16
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17 #include <cstddef>
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18 #include <cstdint>
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19
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20 namespace lld {
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21 namespace macho {
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22 LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
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23
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24 class Symbol;
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25 class InputSection;
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26
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27 enum class RelocAttrBits {
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28 _0 = 0, // invalid
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29 PCREL = 1 << 0, // Value is PC-relative offset
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30 ABSOLUTE = 1 << 1, // Value is an absolute address or fixed offset
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31 BYTE4 = 1 << 2, // 4 byte datum
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32 BYTE8 = 1 << 3, // 8 byte datum
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33 EXTERN = 1 << 4, // Can have an external symbol
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34 LOCAL = 1 << 5, // Can have a local symbol
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35 ADDEND = 1 << 6, // *_ADDEND paired prefix reloc
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36 SUBTRAHEND = 1 << 7, // *_SUBTRACTOR paired prefix reloc
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37 BRANCH = 1 << 8, // Value is branch target
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38 GOT = 1 << 9, // References a symbol in the Global Offset Table
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39 TLV = 1 << 10, // References a thread-local symbol
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40 LOAD = 1 << 11, // Relaxable indirect load
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41 POINTER = 1 << 12, // Non-relaxable indirect load (pointer is taken)
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42 UNSIGNED = 1 << 13, // *_UNSIGNED relocs
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43 LLVM_MARK_AS_BITMASK_ENUM(/*LargestValue*/ (1 << 14) - 1),
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44 };
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45 // Note: SUBTRACTOR always pairs with UNSIGNED (a delta between two symbols).
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46
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47 struct RelocAttrs {
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48 llvm::StringRef name;
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49 RelocAttrBits bits;
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50 bool hasAttr(RelocAttrBits b) const { return (bits & b) == b; }
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51 };
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52
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53 struct Reloc {
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54 uint8_t type = llvm::MachO::GENERIC_RELOC_INVALID;
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55 bool pcrel = false;
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56 uint8_t length = 0;
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57 // The offset from the start of the subsection that this relocation belongs
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58 // to.
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59 uint64_t offset = 0;
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60 // Adding this offset to the address of the referent symbol or subsection
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61 // gives the destination that this relocation refers to.
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62 int64_t addend = 0;
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63 llvm::PointerUnion<Symbol *, InputSection *> referent = nullptr;
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64 };
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65
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66 bool validateSymbolRelocation(const Symbol *, const InputSection *,
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67 const Reloc &);
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68
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69 /*
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70 * v: The value the relocation is attempting to encode
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71 * bits: The number of bits actually available to encode this relocation
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72 */
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73 void reportRangeError(const Reloc &, const llvm::Twine &v, uint8_t bits,
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74 int64_t min, uint64_t max);
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75
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76 struct SymbolDiagnostic {
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77 const Symbol *symbol;
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78 llvm::StringRef reason;
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79 };
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80
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81 void reportRangeError(SymbolDiagnostic, const llvm::Twine &v, uint8_t bits,
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82 int64_t min, uint64_t max);
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83
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84 template <typename Diagnostic>
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85 inline void checkInt(Diagnostic d, int64_t v, int bits) {
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86 if (v != llvm::SignExtend64(v, bits))
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87 reportRangeError(d, llvm::Twine(v), bits, llvm::minIntN(bits),
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88 llvm::maxIntN(bits));
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89 }
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90
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91 template <typename Diagnostic>
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92 inline void checkUInt(Diagnostic d, uint64_t v, int bits) {
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93 if ((v >> bits) != 0)
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94 reportRangeError(d, llvm::Twine(v), bits, 0, llvm::maxUIntN(bits));
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95 }
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96
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97 inline void writeAddress(uint8_t *loc, uint64_t addr, uint8_t length) {
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98 switch (length) {
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99 case 2:
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100 llvm::support::endian::write32le(loc, addr);
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101 break;
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102 case 3:
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103 llvm::support::endian::write64le(loc, addr);
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104 break;
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105 default:
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106 llvm_unreachable("invalid r_length");
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107 }
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108 }
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109
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110 extern const RelocAttrs invalidRelocAttrs;
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111
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112 } // namespace macho
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113 } // namespace lld
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114
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115 #endif
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