diff options
| -rw-r--r-- | llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp | 54 |
1 files changed, 24 insertions, 30 deletions
diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp index c31a090..1a2808f4 100644 --- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp +++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp @@ -162,8 +162,7 @@ public: Register ScratchReg, AArch64PACKey::ID Key, AArch64PAuth::AuthCheckMethod Method, - bool ShouldTrap, - const MCSymbol *OnFailure); + const MCSymbol *OnFailure = nullptr); // Check authenticated LR before tail calling. void emitPtrauthTailCallHardening(const MachineInstr *TC); @@ -1939,14 +1938,19 @@ Register AArch64AsmPrinter::emitPtrauthDiscriminator(uint16_t Disc, return ScratchReg; } -/// Emits a code sequence to check an authenticated pointer value. +/// Emit a code sequence to check an authenticated pointer value. /// -/// If OnFailure argument is passed, jump there on check failure instead -/// of proceeding to the next instruction (only if ShouldTrap is false). +/// This function emits a sequence of instructions that checks if TestedReg was +/// authenticated successfully. On success, execution continues at the next +/// instruction after the sequence. +/// +/// The action performed on failure depends on the OnFailure argument: +/// * if OnFailure is not nullptr, control is transferred to that label after +/// clearing the PAC field +/// * otherwise, BRK instruction is emitted to generate an error void AArch64AsmPrinter::emitPtrauthCheckAuthenticatedValue( Register TestedReg, Register ScratchReg, AArch64PACKey::ID Key, - AArch64PAuth::AuthCheckMethod Method, bool ShouldTrap, - const MCSymbol *OnFailure) { + AArch64PAuth::AuthCheckMethod Method, const MCSymbol *OnFailure) { // Insert a sequence to check if authentication of TestedReg succeeded, // such as: // @@ -1983,7 +1987,7 @@ void AArch64AsmPrinter::emitPtrauthCheckAuthenticatedValue( .addReg(getWRegFromXReg(ScratchReg)) .addReg(TestedReg) .addImm(0)); - assert(ShouldTrap && !OnFailure && "DummyLoad always traps on error"); + assert(!OnFailure && "DummyLoad always traps on error"); return; } @@ -2037,15 +2041,14 @@ void AArch64AsmPrinter::emitPtrauthCheckAuthenticatedValue( llvm_unreachable("Unsupported check method"); } - if (ShouldTrap) { - assert(!OnFailure && "Cannot specify OnFailure with ShouldTrap"); + if (!OnFailure) { // Trapping sequences do a 'brk'. // brk #<0xc470 + aut key> EmitToStreamer(MCInstBuilder(AArch64::BRK).addImm(0xc470 | Key)); } else { // Non-trapping checked sequences return the stripped result in TestedReg, - // skipping over success-only code (such as re-signing the pointer) if - // there is one. + // skipping over success-only code (such as re-signing the pointer) by + // jumping to OnFailure label. // Note that this can introduce an authentication oracle (such as based on // the high bits of the re-signed value). @@ -2070,12 +2073,9 @@ void AArch64AsmPrinter::emitPtrauthCheckAuthenticatedValue( MCInstBuilder(XPACOpc).addReg(TestedReg).addReg(TestedReg)); } - if (OnFailure) { - // b Lend - EmitToStreamer( - MCInstBuilder(AArch64::B) - .addExpr(MCSymbolRefExpr::create(OnFailure, OutContext))); - } + // b Lend + const auto *OnFailureExpr = MCSymbolRefExpr::create(OnFailure, OutContext); + EmitToStreamer(MCInstBuilder(AArch64::B).addExpr(OnFailureExpr)); } // If the auth check succeeds, we can continue. @@ -2102,9 +2102,8 @@ void AArch64AsmPrinter::emitPtrauthTailCallHardening(const MachineInstr *TC) { "Neither x16 nor x17 is available as a scratch register"); AArch64PACKey::ID Key = AArch64FI->shouldSignWithBKey() ? AArch64PACKey::IB : AArch64PACKey::IA; - emitPtrauthCheckAuthenticatedValue( - AArch64::LR, ScratchReg, Key, LRCheckMethod, - /*ShouldTrap=*/true, /*OnFailure=*/nullptr); + emitPtrauthCheckAuthenticatedValue(AArch64::LR, ScratchReg, Key, + LRCheckMethod); } void AArch64AsmPrinter::emitPtrauthAuthResign( @@ -2178,9 +2177,8 @@ void AArch64AsmPrinter::emitPtrauthAuthResign( if (IsAUTPAC && !ShouldTrap) EndSym = createTempSymbol("resign_end_"); - emitPtrauthCheckAuthenticatedValue(AUTVal, Scratch, AUTKey, - AArch64PAuth::AuthCheckMethod::XPAC, - ShouldTrap, EndSym); + emitPtrauthCheckAuthenticatedValue( + AUTVal, Scratch, AUTKey, AArch64PAuth::AuthCheckMethod::XPAC, EndSym); } // We already emitted unchecked and checked-but-non-trapping AUTs. @@ -2519,9 +2517,7 @@ void AArch64AsmPrinter::LowerMOVaddrPAC(const MachineInstr &MI) { : AArch64PACKey::DA); emitPtrauthCheckAuthenticatedValue(AArch64::X16, AArch64::X17, AuthKey, - AArch64PAuth::AuthCheckMethod::XPAC, - /*ShouldTrap=*/true, - /*OnFailure=*/nullptr); + AArch64PAuth::AuthCheckMethod::XPAC); } } else { EmitToStreamer(MCInstBuilder(AArch64::LDRXui) @@ -2654,9 +2650,7 @@ void AArch64AsmPrinter::LowerLOADgotAUTH(const MachineInstr &MI) { (AuthOpcode == AArch64::AUTIA ? AArch64PACKey::IA : AArch64PACKey::DA); emitPtrauthCheckAuthenticatedValue(AuthResultReg, AArch64::X17, AuthKey, - AArch64PAuth::AuthCheckMethod::XPAC, - /*ShouldTrap=*/true, - /*OnFailure=*/nullptr); + AArch64PAuth::AuthCheckMethod::XPAC); emitMovXReg(DstReg, AuthResultReg); } |