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 selrefsVA, uint64_t selectorIndex,
75                                    uint64_t gotAddr,
76                                    uint64_t msgSendIndex) const = 0;
77
78  // Symbols may be referenced via either the GOT or the stubs section,
79  // depending on the relocation type. prepareSymbolRelocation() will set up the
80  // GOT/stubs entries, and resolveSymbolVA() will return the addresses of those
81  // entries. resolveSymbolVA() may also relax the target instructions to save
82  // on a level of address indirection.
83  virtual void relaxGotLoad(uint8_t *loc, uint8_t type) const = 0;
84
85  virtual uint64_t getPageSize() const = 0;
86
87  virtual void populateThunk(InputSection *thunk, Symbol *funcSym) {
88    llvm_unreachable("target does not use thunks");
89  }
90
91  const RelocAttrs &getRelocAttrs(uint8_t type) const {
92    assert(type < relocAttrs.size() && "invalid relocation type");
93    if (type >= relocAttrs.size())
94      return invalidRelocAttrs;
95    return relocAttrs[type];
96  }
97
98  bool hasAttr(uint8_t type, RelocAttrBits bit) const {
99    return getRelocAttrs(type).hasAttr(bit);
100  }
101
102  bool usesThunks() const { return thunkSize > 0; }
103
104  // For now, handleDtraceReloc only implements -no_dtrace_dof, and ensures
105  // that the linking would not fail even when there are user-provided dtrace
106  // symbols. However, unlike ld64, lld currently does not emit __dof sections.
107  virtual void handleDtraceReloc(const Symbol *sym, const Reloc &r,
108                                 uint8_t *loc) const {
109    llvm_unreachable("Unsupported architecture for dtrace symbols");
110  }
111
112  virtual void applyOptimizationHints(uint8_t *, const ObjFile &) const {};
113
114  uint32_t magic;
115  llvm::MachO::CPUType cpuType;
116  uint32_t cpuSubtype;
117
118  uint64_t pageZeroSize;
119  size_t headerSize;
120  size_t stubSize;
121  size_t stubHelperHeaderSize;
122  size_t stubHelperEntrySize;
123  size_t objcStubsFastSize;
124  size_t objcStubsAlignment;
125  uint8_t p2WordSize;
126  size_t wordSize;
127
128  size_t thunkSize = 0;
129  uint64_t forwardBranchRange = 0;
130  uint64_t backwardBranchRange = 0;
131
132  uint32_t modeDwarfEncoding;
133  uint8_t subtractorRelocType;
134  uint8_t unsignedRelocType;
135
136  llvm::ArrayRef<RelocAttrs> relocAttrs;
137
138  // We contrive this value as sufficiently far from any valid address that it
139  // will always be out-of-range for any architecture. UINT64_MAX is not a
140  // good choice because it is (a) only 1 away from wrapping to 0, and (b) the
141  // tombstone value for DenseMap<> and caused weird assertions for me.
142  static constexpr uint64_t outOfRangeVA = 0xfull << 60;
143};
144
145TargetInfo *createX86_64TargetInfo();
146TargetInfo *createARM64TargetInfo();
147TargetInfo *createARM64_32TargetInfo();
148TargetInfo *createARMTargetInfo(uint32_t cpuSubtype);
149
150struct LP64 {
151  using mach_header = llvm::MachO::mach_header_64;
152  using nlist = structs::nlist_64;
153  using segment_command = llvm::MachO::segment_command_64;
154  using section = llvm::MachO::section_64;
155  using encryption_info_command = llvm::MachO::encryption_info_command_64;
156
157  static constexpr uint32_t magic = llvm::MachO::MH_MAGIC_64;
158  static constexpr uint32_t segmentLCType = llvm::MachO::LC_SEGMENT_64;
159  static constexpr uint32_t encryptionInfoLCType =
160      llvm::MachO::LC_ENCRYPTION_INFO_64;
161
162  static constexpr uint64_t pageZeroSize = 1ull << 32;
163  static constexpr size_t wordSize = 8;
164};
165
166struct ILP32 {
167  using mach_header = llvm::MachO::mach_header;
168  using nlist = structs::nlist;
169  using segment_command = llvm::MachO::segment_command;
170  using section = llvm::MachO::section;
171  using encryption_info_command = llvm::MachO::encryption_info_command;
172
173  static constexpr uint32_t magic = llvm::MachO::MH_MAGIC;
174  static constexpr uint32_t segmentLCType = llvm::MachO::LC_SEGMENT;
175  static constexpr uint32_t encryptionInfoLCType =
176      llvm::MachO::LC_ENCRYPTION_INFO;
177
178  static constexpr uint64_t pageZeroSize = 1ull << 12;
179  static constexpr size_t wordSize = 4;
180};
181
182extern TargetInfo *target;
183
184} // namespace lld::macho
185
186#endif
187