https://github.com/arsenm created
https://github.com/llvm/llvm-project/pull/147913
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.
>From 927865a3352eb078e1b4f379bc85561e11234526 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <matthew.arsena...@amd.com>
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 a954dde9fb223..f7598979ca4c5 100644
--- a/llvm/include/llvm/IR/RuntimeLibcalls.td
+++ b/llvm/include/llvm/IR/RuntimeLibcalls.td
@@ -334,6 +334,7 @@ defset list<RuntimeLibcall> LibCalls__OutOfLineAtomic = {
// Stack Protector Fail
def STACKPROTECTOR_CHECK_FAIL : RuntimeLibcall;
+def STACK_SMASH_HANDLER : RuntimeLibcall;
// Deoptimization
def DEOPTIMIZE : RuntimeLibcall;
@@ -918,6 +919,9 @@ def bzero : RuntimeLibcallImpl<BZERO>;
def __bzero : RuntimeLibcallImpl<BZERO>;
def _Unwind_SjLj_Resume : RuntimeLibcallImpl<UNWIND_RESUME>;
+// Used on OpenBSD
+def __stack_smash_handler : RuntimeLibcallImpl<STACK_SMASH_HANDLER>;
+
//===----------------------------------------------------------------------===//
// F128 libm Runtime Libcalls
//===----------------------------------------------------------------------===//
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<ReturnInst>(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<Value *, 1> 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<Function>(StackChkFail.getCallee())->addFnAttr(Attribute::NoReturn);
- B.CreateCall(StackChkFail, Args);
+
+ if (StackChkFail) {
+ cast<Function>(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 fdc183a6b09ce..f9bd9b6029234 100644
--- a/llvm/lib/IR/RuntimeLibcalls.cpp
+++ b/llvm/lib/IR/RuntimeLibcalls.cpp
@@ -272,6 +272,7 @@ 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);
}
if (TT.isOSWindows() && !TT.isOSCygMing()) {
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)
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