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 25 namespace lld::macho { 26 LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE(); 27 28 class Symbol; 29 class Defined; 30 class DylibSymbol; 31 class InputSection; 32 class ObjFile; 33 34 static_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. 41 constexpr uint32_t UNWIND_MODE_MASK = UNWIND_X86_64_MODE_MASK; 42 43 class TargetInfo { 44 public: 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 }; 144 145 TargetInfo *createX86_64TargetInfo(); 146 TargetInfo *createARM64TargetInfo(); 147 TargetInfo *createARM64_32TargetInfo(); 148 149 struct LP64 { 150 using mach_header = llvm::MachO::mach_header_64; 151 using nlist = structs::nlist_64; 152 using segment_command = llvm::MachO::segment_command_64; 153 using section = llvm::MachO::section_64; 154 using encryption_info_command = llvm::MachO::encryption_info_command_64; 155 156 static constexpr uint32_t magic = llvm::MachO::MH_MAGIC_64; 157 static constexpr uint32_t segmentLCType = llvm::MachO::LC_SEGMENT_64; 158 static constexpr uint32_t encryptionInfoLCType = 159 llvm::MachO::LC_ENCRYPTION_INFO_64; 160 161 static constexpr uint64_t pageZeroSize = 1ull << 32; 162 static constexpr size_t wordSize = 8; 163 }; 164 165 struct ILP32 { 166 using mach_header = llvm::MachO::mach_header; 167 using nlist = structs::nlist; 168 using segment_command = llvm::MachO::segment_command; 169 using section = llvm::MachO::section; 170 using encryption_info_command = llvm::MachO::encryption_info_command; 171 172 static constexpr uint32_t magic = llvm::MachO::MH_MAGIC; 173 static constexpr uint32_t segmentLCType = llvm::MachO::LC_SEGMENT; 174 static constexpr uint32_t encryptionInfoLCType = 175 llvm::MachO::LC_ENCRYPTION_INFO; 176 177 static constexpr uint64_t pageZeroSize = 1ull << 12; 178 static constexpr size_t wordSize = 4; 179 }; 180 181 extern TargetInfo *target; 182 183 } // namespace lld::macho 184 185 #endif 186