From c312171fab37ce55ceed897d12b2b4217eda604e Mon Sep 17 00:00:00 2001 From: Matt Arsenault Date: Thu, 10 Jul 2025 14:03:11 +0900 Subject: [PATCH] StackProtector: Use RuntimeLibcalls to query libcall names The compiler should not introduce calls to arbitrary strings that aren't defined in RuntimeLibcalls. Previously OpenBSD was disabling the default __stack_chk_fail, but there was no record of the alternative __stack_smash_handler function it emits instead. This also avoids a random triple check in the pass. --- llvm/include/llvm/IR/RuntimeLibcalls.td | 4 +++ llvm/lib/CodeGen/StackProtector.cpp | 28 ++++++++++++------- llvm/lib/IR/RuntimeLibcalls.cpp | 1 + .../NVPTX/no-stack-protector-libcall-error.ll | 10 +++++++ 4 files changed, 33 insertions(+), 10 deletions(-) create mode 100644 llvm/test/CodeGen/NVPTX/no-stack-protector-libcall-error.ll diff --git a/llvm/include/llvm/IR/RuntimeLibcalls.td b/llvm/include/llvm/IR/RuntimeLibcalls.td index 267ca6f653eab..077b493dea590 100644 --- a/llvm/include/llvm/IR/RuntimeLibcalls.td +++ b/llvm/include/llvm/IR/RuntimeLibcalls.td @@ -357,6 +357,7 @@ defset list LibCalls__OutOfLineAtomic = { // Stack Protector Fail def STACKPROTECTOR_CHECK_FAIL : RuntimeLibcall; +def STACK_SMASH_HANDLER : RuntimeLibcall; // Deoptimization def DEOPTIMIZE : RuntimeLibcall; @@ -987,6 +988,9 @@ def bzero : RuntimeLibcallImpl; def __bzero : RuntimeLibcallImpl; def _Unwind_SjLj_Resume : RuntimeLibcallImpl; +// Used on OpenBSD +def __stack_smash_handler : RuntimeLibcallImpl; + def __riscv_flush_icache : RuntimeLibcallImpl; //===----------------------------------------------------------------------===// diff --git a/llvm/lib/CodeGen/StackProtector.cpp b/llvm/lib/CodeGen/StackProtector.cpp index 5f866eea7d4e7..3ec70083b7043 100644 --- a/llvm/lib/CodeGen/StackProtector.cpp +++ b/llvm/lib/CodeGen/StackProtector.cpp @@ -76,7 +76,7 @@ static bool InsertStackProtectors(const TargetMachine *TM, Function *F, /// CreateFailBB - Create a basic block to jump to when the stack protector /// check fails. -static BasicBlock *CreateFailBB(Function *F, const Triple &Trip); +static BasicBlock *CreateFailBB(Function *F, const TargetLowering &TLI); bool SSPLayoutInfo::shouldEmitSDCheck(const BasicBlock &BB) const { return HasPrologue && !HasIRCheck && isa(BB.getTerminator()); @@ -673,7 +673,7 @@ bool InsertStackProtectors(const TargetMachine *TM, Function *F, // merge pass will merge together all of the various BB into one including // fail BB generated by the stack protector pseudo instruction. if (!FailBB) - FailBB = CreateFailBB(F, TM->getTargetTriple()); + FailBB = CreateFailBB(F, *TLI); IRBuilder<> B(CheckLoc); Value *Guard = getStackGuard(TLI, M, B); @@ -706,7 +706,7 @@ bool InsertStackProtectors(const TargetMachine *TM, Function *F, return HasPrologue; } -BasicBlock *CreateFailBB(Function *F, const Triple &Trip) { +BasicBlock *CreateFailBB(Function *F, const TargetLowering &TLI) { auto *M = F->getParent(); LLVMContext &Context = F->getContext(); BasicBlock *FailBB = BasicBlock::Create(Context, "CallStackCheckFailBlk", F); @@ -716,17 +716,25 @@ BasicBlock *CreateFailBB(Function *F, const Triple &Trip) { DILocation::get(Context, 0, 0, F->getSubprogram())); FunctionCallee StackChkFail; SmallVector Args; - if (Trip.isOSOpenBSD()) { - StackChkFail = M->getOrInsertFunction("__stack_smash_handler", - Type::getVoidTy(Context), + + if (const char *ChkFailName = + TLI.getLibcallName(RTLIB::STACKPROTECTOR_CHECK_FAIL)) { + StackChkFail = + M->getOrInsertFunction(ChkFailName, Type::getVoidTy(Context)); + } else if (const char *SSHName = + TLI.getLibcallName(RTLIB::STACK_SMASH_HANDLER)) { + StackChkFail = M->getOrInsertFunction(SSHName, Type::getVoidTy(Context), PointerType::getUnqual(Context)); Args.push_back(B.CreateGlobalString(F->getName(), "SSH")); } else { - StackChkFail = - M->getOrInsertFunction("__stack_chk_fail", Type::getVoidTy(Context)); + Context.emitError("no libcall available for stack protector"); } - cast(StackChkFail.getCallee())->addFnAttr(Attribute::NoReturn); - B.CreateCall(StackChkFail, Args); + + if (StackChkFail) { + cast(StackChkFail.getCallee())->addFnAttr(Attribute::NoReturn); + B.CreateCall(StackChkFail, Args); + } + B.CreateUnreachable(); return FailBB; } diff --git a/llvm/lib/IR/RuntimeLibcalls.cpp b/llvm/lib/IR/RuntimeLibcalls.cpp index 84c67010ca716..6624e24cc7cf5 100644 --- a/llvm/lib/IR/RuntimeLibcalls.cpp +++ b/llvm/lib/IR/RuntimeLibcalls.cpp @@ -100,6 +100,7 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT, if (TT.isOSOpenBSD()) { setLibcallImpl(RTLIB::STACKPROTECTOR_CHECK_FAIL, RTLIB::Unsupported); + setLibcallImpl(RTLIB::STACK_SMASH_HANDLER, RTLIB::__stack_smash_handler); } // Skip default manual processing for targets that have been fully ported to diff --git a/llvm/test/CodeGen/NVPTX/no-stack-protector-libcall-error.ll b/llvm/test/CodeGen/NVPTX/no-stack-protector-libcall-error.ll new file mode 100644 index 0000000000000..f877d95dd3769 --- /dev/null +++ b/llvm/test/CodeGen/NVPTX/no-stack-protector-libcall-error.ll @@ -0,0 +1,10 @@ +; RUN: not opt -disable-output -mtriple=nvptx64-- -enable-selectiondag-sp=0 -passes=stack-protector %s 2>&1 | FileCheck %s + +; CHECK: error: no libcall available for stack protector +define void @func() sspreq nounwind { + %alloca = alloca i32, align 4 + call void @capture(ptr %alloca) + ret void +} + +declare void @capture(ptr)