Support OpenBSD's native frame protection conventions.
OpenBSD's stack smashing protection differs slightly from other
platforms:
1. The smash handler function is "__stack_smash_handler(const char
*funcname)" instead of "__stack_chk_fail(void)".
2. There's a hidden "long __guard_local" object that gets linked
into each executable and DSO.
Patch by Matthew Dempsky.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183533 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/StackProtector.cpp b/lib/CodeGen/StackProtector.cpp
index fbef347..389793e 100644
--- a/lib/CodeGen/StackProtector.cpp
+++ b/lib/CodeGen/StackProtector.cpp
@@ -25,6 +25,8 @@
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
+#include "llvm/IR/GlobalValue.h"
+#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Module.h"
@@ -41,7 +43,8 @@
class StackProtector : public FunctionPass {
/// TLI - Keep a pointer of a TargetLowering to consult for determining
/// target type sizes.
- const TargetLoweringBase *TLI;
+ const TargetLoweringBase *const TLI;
+ const Triple Trip;
Function *F;
Module *M;
@@ -84,7 +87,8 @@
initializeStackProtectorPass(*PassRegistry::getPassRegistry());
}
StackProtector(const TargetLoweringBase *tli)
- : FunctionPass(ID), TLI(tli) {
+ : FunctionPass(ID), TLI(tli),
+ Trip(tli->getTargetMachine().getTargetTriple()) {
initializeStackProtectorPass(*PassRegistry::getPassRegistry());
}
@@ -128,8 +132,6 @@
return true;
const TargetMachine &TM = TLI->getTargetMachine();
if (!AT->getElementType()->isIntegerTy(8)) {
- Triple Trip(TM.getTargetTriple());
-
// If we're on a non-Darwin platform or we're inside of a structure, don't
// add stack protectors unless the array is a character array.
if (InStruct || !Trip.isOSDarwin())
@@ -283,6 +285,10 @@
StackGuardVar = ConstantExpr::getIntToPtr(OffsetVal,
PointerType::get(PtrTy, AddressSpace));
+ } else if (Trip.getOS() == llvm::Triple::OpenBSD) {
+ StackGuardVar = M->getOrInsertGlobal("__guard_local", PtrTy);
+ cast<GlobalValue>(StackGuardVar)
+ ->setVisibility(GlobalValue::HiddenVisibility);
} else {
StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", PtrTy);
}
@@ -359,12 +365,31 @@
/// CreateFailBB - Create a basic block to jump to when the stack protector
/// check fails.
BasicBlock *StackProtector::CreateFailBB() {
- BasicBlock *FailBB = BasicBlock::Create(F->getContext(),
- "CallStackCheckFailBlk", F);
- Constant *StackChkFail =
- M->getOrInsertFunction("__stack_chk_fail",
- Type::getVoidTy(F->getContext()), NULL);
- CallInst::Create(StackChkFail, "", FailBB);
- new UnreachableInst(F->getContext(), FailBB);
+ LLVMContext &Context = F->getContext();
+ BasicBlock *FailBB = BasicBlock::Create(Context, "CallStackCheckFailBlk", F);
+ if (Trip.getOS() == llvm::Triple::OpenBSD) {
+ Constant *StackChkFail = M->getOrInsertFunction(
+ "__stack_smash_handler", Type::getVoidTy(Context),
+ Type::getInt8PtrTy(Context), NULL);
+
+ Constant *NameStr = ConstantDataArray::getString(Context, F->getName());
+ Constant *FuncName =
+ new GlobalVariable(*M, NameStr->getType(), true,
+ GlobalVariable::PrivateLinkage, NameStr, "SSH");
+
+ SmallVector<Constant *, 2> IdxList;
+ IdxList.push_back(ConstantInt::get(Type::getInt8Ty(Context), 0));
+ IdxList.push_back(ConstantInt::get(Type::getInt8Ty(Context), 0));
+
+ SmallVector<Value *, 1> Args;
+ Args.push_back(ConstantExpr::getGetElementPtr(FuncName, IdxList));
+
+ CallInst::Create(StackChkFail, Args, "", FailBB);
+ } else {
+ Constant *StackChkFail = M->getOrInsertFunction(
+ "__stack_chk_fail", Type::getVoidTy(Context), NULL);
+ CallInst::Create(StackChkFail, "", FailBB);
+ }
+ new UnreachableInst(Context, FailBB);
return FailBB;
}