1//===- Target.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_TARGET_H
10#define LLD_MACHO_TARGET_H
11
12#include "MachOStructs.h"
13#include "Relocations.h"
14
15#include "llvm/ADT/BitmaskEnum.h"
16#include "llvm/BinaryFormat/MachO.h"
17#include "llvm/Support/MathExtras.h"
18#include "llvm/Support/MemoryBuffer.h"
19
20#include <cstddef>
21#include <cstdint>
22
23#include "mach-o/compact_unwind_encoding.h"
24
25namespace lld::macho {
26LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
27
28class Symbol;
29class Defined;
30class DylibSymbol;
31class InputSection;
32class ObjFile;
33
34static_assert(static_cast<uint32_t>(UNWIND_X86_64_MODE_MASK) ==
35 static_cast<uint32_t>(UNWIND_X86_MODE_MASK) &&
36 static_cast<uint32_t>(UNWIND_ARM64_MODE_MASK) ==
37 static_cast<uint32_t>(UNWIND_X86_64_MODE_MASK));
38
39// Since the mode masks have the same value on all targets, define
40// a common one for convenience.
41constexpr uint32_t UNWIND_MODE_MASK = UNWIND_X86_64_MODE_MASK;
42
43class TargetInfo {
44public:
45 template <class LP> TargetInfo(LP) {
46 // Having these values available in TargetInfo allows us to access them
47 // without having to resort to templates.
48 magic = LP::magic;
49 pageZeroSize = LP::pageZeroSize;
50 headerSize = sizeof(typename LP::mach_header);
51 wordSize = LP::wordSize;
52 p2WordSize = llvm::CTLog2<LP::wordSize>();
53 }
54
55 virtual ~TargetInfo() = default;
56
57 // Validate the relocation structure and get its addend.
58 virtual int64_t
59 getEmbeddedAddend(llvm::MemoryBufferRef, uint64_t offset,
60 const llvm::MachO::relocation_info) const = 0;
61 virtual void relocateOne(uint8_t *loc, const Reloc &, uint64_t va,
62 uint64_t relocVA) const = 0;
63
64 // Write code for lazy binding. See the comments on StubsSection for more
65 // details.
66 virtual void writeStub(uint8_t *buf, const Symbol &,
67 uint64_t pointerVA) const = 0;
68 virtual void writeStubHelperHeader(uint8_t *buf) const = 0;
69 virtual void writeStubHelperEntry(uint8_t *buf, const Symbol &,
70 uint64_t entryAddr) const = 0;
71
72 virtual void writeObjCMsgSendStub(uint8_t *buf, Symbol *sym,
73 uint64_t stubsAddr, uint64_t &stubOffset,
74 uint64_t selrefVA,
75 Symbol *objcMsgSend) const = 0;
76
77 // Init 'thunk' so that it be a direct jump to 'branchTarget'.
78 virtual void initICFSafeThunkBody(InputSection *thunk,
79 Symbol *targetSym) const {
80 llvm_unreachable("target does not support ICF safe thunks");
81 }
82
83 // Given a thunk for which `initICFSafeThunkBody` was called, return the
84 // branchTarget it was initialized with.
85 virtual Symbol *getThunkBranchTarget(InputSection *thunk) const {
86 llvm_unreachable("target does not support ICF safe thunks");
87 }
88
89 virtual uint32_t getICFSafeThunkSize() const {
90 llvm_unreachable("target does not support ICF safe thunks");
91 }
92
93 // Symbols may be referenced via either the GOT or the stubs section,
94 // depending on the relocation type. prepareSymbolRelocation() will set up the
95 // GOT/stubs entries, and resolveSymbolVA() will return the addresses of those
96 // entries. resolveSymbolVA() may also relax the target instructions to save
97 // on a level of address indirection.
98 virtual void relaxGotLoad(uint8_t *loc, uint8_t type) const = 0;
99
100 virtual uint64_t getPageSize() const = 0;
101
102 virtual void populateThunk(InputSection *thunk, Symbol *funcSym) {
103 llvm_unreachable("target does not use thunks");
104 }
105
106 const RelocAttrs &getRelocAttrs(uint8_t type) const {
107 assert(type < relocAttrs.size() && "invalid relocation type");
108 if (type >= relocAttrs.size())
109 return invalidRelocAttrs;
110 return relocAttrs[type];
111 }
112
113 bool hasAttr(uint8_t type, RelocAttrBits bit) const {
114 return getRelocAttrs(type).hasAttr(b: bit);
115 }
116
117 bool usesThunks() const { return thunkSize > 0; }
118
119 // For now, handleDtraceReloc only implements -no_dtrace_dof, and ensures
120 // that the linking would not fail even when there are user-provided dtrace
121 // symbols. However, unlike ld64, lld currently does not emit __dof sections.
122 virtual void handleDtraceReloc(const Symbol *sym, const Reloc &r,
123 uint8_t *loc) const {
124 llvm_unreachable("Unsupported architecture for dtrace symbols");
125 }
126
127 virtual void applyOptimizationHints(uint8_t *, const ObjFile &) const {};
128
129 uint32_t magic;
130 llvm::MachO::CPUType cpuType;
131 uint32_t cpuSubtype;
132
133 uint64_t pageZeroSize;
134 size_t headerSize;
135 size_t stubSize;
136 size_t stubHelperHeaderSize;
137 size_t stubHelperEntrySize;
138 size_t objcStubsFastSize;
139 size_t objcStubsSmallSize;
140 size_t objcStubsFastAlignment;
141 size_t objcStubsSmallAlignment;
142 uint8_t p2WordSize;
143 size_t wordSize;
144
145 size_t thunkSize = 0;
146 uint64_t forwardBranchRange = 0;
147 uint64_t backwardBranchRange = 0;
148
149 uint32_t modeDwarfEncoding;
150 uint8_t subtractorRelocType;
151 uint8_t unsignedRelocType;
152
153 llvm::ArrayRef<RelocAttrs> relocAttrs;
154
155 // We contrive this value as sufficiently far from any valid address that it
156 // will always be out-of-range for any architecture. UINT64_MAX is not a
157 // good choice because it is (a) only 1 away from wrapping to 0, and (b) the
158 // tombstone value for DenseMap<> and caused weird assertions for me.
159 static constexpr uint64_t outOfRangeVA = 0xfull << 60;
160};
161
162TargetInfo *createX86_64TargetInfo();
163TargetInfo *createARM64TargetInfo();
164TargetInfo *createARM64_32TargetInfo();
165
166struct LP64 {
167 using mach_header = llvm::MachO::mach_header_64;
168 using nlist = structs::nlist_64;
169 using segment_command = llvm::MachO::segment_command_64;
170 using section = llvm::MachO::section_64;
171 using encryption_info_command = llvm::MachO::encryption_info_command_64;
172
173 static constexpr uint32_t magic = llvm::MachO::MH_MAGIC_64;
174 static constexpr uint32_t segmentLCType = llvm::MachO::LC_SEGMENT_64;
175 static constexpr uint32_t encryptionInfoLCType =
176 llvm::MachO::LC_ENCRYPTION_INFO_64;
177
178 static constexpr uint64_t pageZeroSize = 1ull << 32;
179 static constexpr size_t wordSize = 8;
180};
181
182struct ILP32 {
183 using mach_header = llvm::MachO::mach_header;
184 using nlist = structs::nlist;
185 using segment_command = llvm::MachO::segment_command;
186 using section = llvm::MachO::section;
187 using encryption_info_command = llvm::MachO::encryption_info_command;
188
189 static constexpr uint32_t magic = llvm::MachO::MH_MAGIC;
190 static constexpr uint32_t segmentLCType = llvm::MachO::LC_SEGMENT;
191 static constexpr uint32_t encryptionInfoLCType =
192 llvm::MachO::LC_ENCRYPTION_INFO;
193
194 static constexpr uint64_t pageZeroSize = 1ull << 12;
195 static constexpr size_t wordSize = 4;
196};
197
198extern TargetInfo *target;
199
200} // namespace lld::macho
201
202#endif
203