1 //===-- AArch64TargetObjectFile.cpp - AArch64 Object Info -----------------===// 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 "AArch64TargetObjectFile.h" 10 #include "AArch64TargetMachine.h" 11 #include "MCTargetDesc/AArch64MCExpr.h" 12 #include "MCTargetDesc/AArch64TargetStreamer.h" 13 #include "llvm/BinaryFormat/Dwarf.h" 14 #include "llvm/CodeGen/MachineModuleInfoImpls.h" 15 #include "llvm/IR/Mangler.h" 16 #include "llvm/IR/Module.h" 17 #include "llvm/MC/MCContext.h" 18 #include "llvm/MC/MCExpr.h" 19 #include "llvm/MC/MCStreamer.h" 20 #include "llvm/MC/MCValue.h" 21 using namespace llvm; 22 using namespace dwarf; 23 24 void AArch64_ELFTargetObjectFile::Initialize(MCContext &Ctx, 25 const TargetMachine &TM) { 26 TargetLoweringObjectFileELF::Initialize(Ctx, TM); 27 // AARCH64 ELF ABI does not define static relocation type for TLS offset 28 // within a module. Do not generate AT_location for TLS variables. 29 SupportDebugThreadLocalLocation = false; 30 } 31 32 void AArch64_ELFTargetObjectFile::emitPersonalityValueImpl( 33 MCStreamer &Streamer, const DataLayout &DL, const MCSymbol *Sym, 34 const MachineModuleInfo *MMI) const { 35 if (!MMI->getObjFileInfo<MachineModuleInfoELF>().hasSignedPersonality()) { 36 TargetLoweringObjectFileELF::emitPersonalityValueImpl(Streamer, DL, Sym, 37 MMI); 38 return; 39 } 40 auto *TS = static_cast<AArch64TargetStreamer *>(Streamer.getTargetStreamer()); 41 // The value is ptrauth_string_discriminator("personality") 42 constexpr uint16_t Discriminator = 0x7EAD; 43 TS->emitAuthValue(MCSymbolRefExpr::create(Sym, getContext()), Discriminator, 44 AArch64PACKey::IA, /*HasAddressDiversity=*/true); 45 } 46 47 const MCExpr *AArch64_ELFTargetObjectFile::getIndirectSymViaGOTPCRel( 48 const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV, 49 int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const { 50 int64_t FinalOffset = Offset + MV.getConstant(); 51 const MCExpr *Res = 52 MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext()); 53 const MCExpr *Off = MCConstantExpr::create(FinalOffset, getContext()); 54 return MCBinaryExpr::createAdd(Res, Off, getContext()); 55 } 56 57 AArch64_MachoTargetObjectFile::AArch64_MachoTargetObjectFile() { 58 SupportGOTPCRelWithOffset = false; 59 } 60 61 const MCExpr *AArch64_MachoTargetObjectFile::getTTypeGlobalReference( 62 const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM, 63 MachineModuleInfo *MMI, MCStreamer &Streamer) const { 64 // On Darwin, we can reference dwarf symbols with foo@GOT-., which 65 // is an indirect pc-relative reference. The default implementation 66 // won't reference using the GOT, so we need this target-specific 67 // version. 68 if (Encoding & (DW_EH_PE_indirect | DW_EH_PE_pcrel)) { 69 const MCSymbol *Sym = TM.getSymbol(GV); 70 const MCExpr *Res = 71 MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOT, getContext()); 72 MCSymbol *PCSym = getContext().createTempSymbol(); 73 Streamer.emitLabel(PCSym); 74 const MCExpr *PC = MCSymbolRefExpr::create(PCSym, getContext()); 75 return MCBinaryExpr::createSub(Res, PC, getContext()); 76 } 77 78 return TargetLoweringObjectFileMachO::getTTypeGlobalReference( 79 GV, Encoding, TM, MMI, Streamer); 80 } 81 82 MCSymbol *AArch64_MachoTargetObjectFile::getCFIPersonalitySymbol( 83 const GlobalValue *GV, const TargetMachine &TM, 84 MachineModuleInfo *MMI) const { 85 return TM.getSymbol(GV); 86 } 87 88 const MCExpr *AArch64_MachoTargetObjectFile::getIndirectSymViaGOTPCRel( 89 const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV, 90 int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const { 91 assert((Offset+MV.getConstant() == 0) && 92 "Arch64 does not support GOT PC rel with extra offset"); 93 // On ARM64 Darwin, we can reference symbols with foo@GOT-., which 94 // is an indirect pc-relative reference. 95 const MCExpr *Res = 96 MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOT, getContext()); 97 MCSymbol *PCSym = getContext().createTempSymbol(); 98 Streamer.emitLabel(PCSym); 99 const MCExpr *PC = MCSymbolRefExpr::create(PCSym, getContext()); 100 return MCBinaryExpr::createSub(Res, PC, getContext()); 101 } 102 103 void AArch64_MachoTargetObjectFile::getNameWithPrefix( 104 SmallVectorImpl<char> &OutName, const GlobalValue *GV, 105 const TargetMachine &TM) const { 106 // AArch64 does not use section-relative relocations so any global symbol must 107 // be accessed via at least a linker-private symbol. 108 getMangler().getNameWithPrefix(OutName, GV, /* CannotUsePrivateLabel */ true); 109 } 110 111 template <typename MachineModuleInfoTarget> 112 static MCSymbol *getAuthPtrSlotSymbolHelper( 113 MCContext &Ctx, const TargetMachine &TM, MachineModuleInfo *MMI, 114 MachineModuleInfoTarget &TargetMMI, const MCSymbol *RawSym, 115 AArch64PACKey::ID Key, uint16_t Discriminator) { 116 const DataLayout &DL = MMI->getModule()->getDataLayout(); 117 118 MCSymbol *StubSym = Ctx.getOrCreateSymbol( 119 DL.getLinkerPrivateGlobalPrefix() + RawSym->getName() + 120 Twine("$auth_ptr$") + AArch64PACKeyIDToString(Key) + Twine('$') + 121 Twine(Discriminator)); 122 123 const MCExpr *&StubAuthPtrRef = TargetMMI.getAuthPtrStubEntry(StubSym); 124 125 if (StubAuthPtrRef) 126 return StubSym; 127 128 const MCExpr *Sym = MCSymbolRefExpr::create(RawSym, Ctx); 129 130 StubAuthPtrRef = 131 AArch64AuthMCExpr::create(Sym, Discriminator, Key, 132 /*HasAddressDiversity=*/false, Ctx); 133 return StubSym; 134 } 135 136 MCSymbol *AArch64_ELFTargetObjectFile::getAuthPtrSlotSymbol( 137 const TargetMachine &TM, MachineModuleInfo *MMI, const MCSymbol *RawSym, 138 AArch64PACKey::ID Key, uint16_t Discriminator) const { 139 auto &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>(); 140 return getAuthPtrSlotSymbolHelper(getContext(), TM, MMI, ELFMMI, RawSym, Key, 141 Discriminator); 142 } 143 144 MCSymbol *AArch64_MachoTargetObjectFile::getAuthPtrSlotSymbol( 145 const TargetMachine &TM, MachineModuleInfo *MMI, const MCSymbol *RawSym, 146 AArch64PACKey::ID Key, uint16_t Discriminator) const { 147 auto &MachOMMI = MMI->getObjFileInfo<MachineModuleInfoMachO>(); 148 return getAuthPtrSlotSymbolHelper(getContext(), TM, MMI, MachOMMI, RawSym, 149 Key, Discriminator); 150 } 151