1 //===- ARM64.cpp ----------------------------------------------------------===// 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 #include "Arch/ARM64Common.h" 10 #include "InputFiles.h" 11 #include "Symbols.h" 12 #include "SyntheticSections.h" 13 #include "Target.h" 14 15 #include "lld/Common/ErrorHandler.h" 16 #include "llvm/ADT/SmallVector.h" 17 #include "llvm/ADT/StringRef.h" 18 #include "llvm/BinaryFormat/MachO.h" 19 #include "llvm/Support/Endian.h" 20 #include "llvm/Support/MathExtras.h" 21 22 using namespace llvm; 23 using namespace llvm::MachO; 24 using namespace llvm::support::endian; 25 using namespace lld; 26 using namespace lld::macho; 27 28 namespace { 29 30 struct ARM64 : ARM64Common { 31 ARM64(); 32 void writeStub(uint8_t *buf, const Symbol &) const override; 33 void writeStubHelperHeader(uint8_t *buf) const override; 34 void writeStubHelperEntry(uint8_t *buf, const DylibSymbol &, 35 uint64_t entryAddr) const override; 36 const RelocAttrs &getRelocAttrs(uint8_t type) const override; 37 void populateThunk(InputSection *thunk, Symbol *funcSym) override; 38 }; 39 40 } // namespace 41 42 // Random notes on reloc types: 43 // ADDEND always pairs with BRANCH26, PAGE21, or PAGEOFF12 44 // POINTER_TO_GOT: ld64 supports a 4-byte pc-relative form as well as an 8-byte 45 // absolute version of this relocation. The semantics of the absolute relocation 46 // are weird -- it results in the value of the GOT slot being written, instead 47 // of the address. Let's not support it unless we find a real-world use case. 48 49 const RelocAttrs &ARM64::getRelocAttrs(uint8_t type) const { 50 static const std::array<RelocAttrs, 11> relocAttrsArray{{ 51 #define B(x) RelocAttrBits::x 52 {"UNSIGNED", 53 B(UNSIGNED) | B(ABSOLUTE) | B(EXTERN) | B(LOCAL) | B(BYTE4) | B(BYTE8)}, 54 {"SUBTRACTOR", B(SUBTRAHEND) | B(EXTERN) | B(BYTE4) | B(BYTE8)}, 55 {"BRANCH26", B(PCREL) | B(EXTERN) | B(BRANCH) | B(BYTE4)}, 56 {"PAGE21", B(PCREL) | B(EXTERN) | B(BYTE4)}, 57 {"PAGEOFF12", B(ABSOLUTE) | B(EXTERN) | B(BYTE4)}, 58 {"GOT_LOAD_PAGE21", B(PCREL) | B(EXTERN) | B(GOT) | B(BYTE4)}, 59 {"GOT_LOAD_PAGEOFF12", 60 B(ABSOLUTE) | B(EXTERN) | B(GOT) | B(LOAD) | B(BYTE4)}, 61 {"POINTER_TO_GOT", B(PCREL) | B(EXTERN) | B(GOT) | B(POINTER) | B(BYTE4)}, 62 {"TLVP_LOAD_PAGE21", B(PCREL) | B(EXTERN) | B(TLV) | B(BYTE4)}, 63 {"TLVP_LOAD_PAGEOFF12", 64 B(ABSOLUTE) | B(EXTERN) | B(TLV) | B(LOAD) | B(BYTE4)}, 65 {"ADDEND", B(ADDEND)}, 66 #undef B 67 }}; 68 assert(type < relocAttrsArray.size() && "invalid relocation type"); 69 if (type >= relocAttrsArray.size()) 70 return invalidRelocAttrs; 71 return relocAttrsArray[type]; 72 } 73 74 static constexpr uint32_t stubCode[] = { 75 0x90000010, // 00: adrp x16, __la_symbol_ptr@page 76 0xf9400210, // 04: ldr x16, [x16, __la_symbol_ptr@pageoff] 77 0xd61f0200, // 08: br x16 78 }; 79 80 void ARM64::writeStub(uint8_t *buf8, const Symbol &sym) const { 81 ::writeStub<LP64>(buf8, stubCode, sym); 82 } 83 84 static constexpr uint32_t stubHelperHeaderCode[] = { 85 0x90000011, // 00: adrp x17, _dyld_private@page 86 0x91000231, // 04: add x17, x17, _dyld_private@pageoff 87 0xa9bf47f0, // 08: stp x16/x17, [sp, #-16]! 88 0x90000010, // 0c: adrp x16, dyld_stub_binder@page 89 0xf9400210, // 10: ldr x16, [x16, dyld_stub_binder@pageoff] 90 0xd61f0200, // 14: br x16 91 }; 92 93 void ARM64::writeStubHelperHeader(uint8_t *buf8) const { 94 ::writeStubHelperHeader<LP64>(buf8, stubHelperHeaderCode); 95 } 96 97 static constexpr uint32_t stubHelperEntryCode[] = { 98 0x18000050, // 00: ldr w16, l0 99 0x14000000, // 04: b stubHelperHeader 100 0x00000000, // 08: l0: .long 0 101 }; 102 103 void ARM64::writeStubHelperEntry(uint8_t *buf8, const DylibSymbol &sym, 104 uint64_t entryVA) const { 105 ::writeStubHelperEntry(buf8, stubHelperEntryCode, sym, entryVA); 106 } 107 108 // A thunk is the relaxed variation of stubCode. We don't need the 109 // extra indirection through a lazy pointer because the target address 110 // is known at link time. 111 static constexpr uint32_t thunkCode[] = { 112 0x90000010, // 00: adrp x16, <thunk.ptr>@page 113 0x91000210, // 04: add x16, [x16,<thunk.ptr>@pageoff] 114 0xd61f0200, // 08: br x16 115 }; 116 117 void ARM64::populateThunk(InputSection *thunk, Symbol *funcSym) { 118 thunk->align = 4; 119 thunk->data = {reinterpret_cast<const uint8_t *>(thunkCode), 120 sizeof(thunkCode)}; 121 thunk->relocs.push_back({/*type=*/ARM64_RELOC_PAGEOFF12, 122 /*pcrel=*/false, /*length=*/2, 123 /*offset=*/4, /*addend=*/0, 124 /*referent=*/funcSym}); 125 thunk->relocs.push_back({/*type=*/ARM64_RELOC_PAGE21, 126 /*pcrel=*/true, /*length=*/2, 127 /*offset=*/0, /*addend=*/0, 128 /*referent=*/funcSym}); 129 } 130 131 ARM64::ARM64() : ARM64Common(LP64()) { 132 cpuType = CPU_TYPE_ARM64; 133 cpuSubtype = CPU_SUBTYPE_ARM64_ALL; 134 135 stubSize = sizeof(stubCode); 136 thunkSize = sizeof(thunkCode); 137 branchRange = maxIntN(28) - thunkSize; 138 stubHelperHeaderSize = sizeof(stubHelperHeaderCode); 139 stubHelperEntrySize = sizeof(stubHelperEntryCode); 140 } 141 142 TargetInfo *macho::createARM64TargetInfo() { 143 static ARM64 t; 144 return &t; 145 } 146