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-rw-r--r--lib/CodeGen/StackProtector.cpp114
1 files changed, 67 insertions, 47 deletions
diff --git a/lib/CodeGen/StackProtector.cpp b/lib/CodeGen/StackProtector.cpp
index 389793e..4c56380 100644
--- a/lib/CodeGen/StackProtector.cpp
+++ b/lib/CodeGen/StackProtector.cpp
@@ -33,6 +33,7 @@
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetLowering.h"
+#include <cstdlib>
using namespace llvm;
STATISTIC(NumFunProtected, "Number of functions protected");
@@ -41,9 +42,11 @@ STATISTIC(NumAddrTaken, "Number of local variables that have their address"
namespace {
class StackProtector : public FunctionPass {
+ const TargetMachine *TM;
+
/// TLI - Keep a pointer of a TargetLowering to consult for determining
/// target type sizes.
- const TargetLoweringBase *const TLI;
+ const TargetLoweringBase *TLI;
const Triple Trip;
Function *F;
@@ -51,6 +54,10 @@ namespace {
DominatorTree *DT;
+ /// \brief The minimum size of buffers that will receive stack smashing
+ /// protection when -fstack-protection is used.
+ unsigned SSPBufferSize;
+
/// VisitedPHIs - The set of PHI nodes visited when determining
/// if a variable's reference has been taken. This set
/// is maintained to ensure we don't visit the same PHI node multiple
@@ -83,12 +90,12 @@ namespace {
bool RequiresStackProtector();
public:
static char ID; // Pass identification, replacement for typeid.
- StackProtector() : FunctionPass(ID), TLI(0) {
+ StackProtector() : FunctionPass(ID), TM(0), TLI(0), SSPBufferSize(0) {
initializeStackProtectorPass(*PassRegistry::getPassRegistry());
}
- StackProtector(const TargetLoweringBase *tli)
- : FunctionPass(ID), TLI(tli),
- Trip(tli->getTargetMachine().getTargetTriple()) {
+ StackProtector(const TargetMachine *TM)
+ : FunctionPass(ID), TM(TM), TLI(0), Trip(TM->getTargetTriple()),
+ SSPBufferSize(8) {
initializeStackProtectorPass(*PassRegistry::getPassRegistry());
}
@@ -104,17 +111,24 @@ char StackProtector::ID = 0;
INITIALIZE_PASS(StackProtector, "stack-protector",
"Insert stack protectors", false, false)
-FunctionPass *llvm::createStackProtectorPass(const TargetLoweringBase *tli) {
- return new StackProtector(tli);
+FunctionPass *llvm::createStackProtectorPass(const TargetMachine *TM) {
+ return new StackProtector(TM);
}
bool StackProtector::runOnFunction(Function &Fn) {
F = &Fn;
M = F->getParent();
DT = getAnalysisIfAvailable<DominatorTree>();
+ TLI = TM->getTargetLowering();
if (!RequiresStackProtector()) return false;
+ Attribute Attr =
+ Fn.getAttributes().getAttribute(AttributeSet::FunctionIndex,
+ "stack-protector-buffer-size");
+ if (Attr.isStringAttribute())
+ SSPBufferSize = atoi(Attr.getValueAsString().data());
+
++NumFunProtected;
return InsertStackProtectors();
}
@@ -130,7 +144,6 @@ bool StackProtector::ContainsProtectableArray(Type *Ty, bool Strong,
// protector
if (Strong)
return true;
- const TargetMachine &TM = TLI->getTargetMachine();
if (!AT->getElementType()->isIntegerTy(8)) {
// 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.
@@ -140,7 +153,7 @@ bool StackProtector::ContainsProtectableArray(Type *Ty, bool Strong,
// If an array has more than SSPBufferSize bytes of allocated space, then we
// emit stack protectors.
- if (TM.Options.SSPBufferSize <= TLI->getDataLayout()->getTypeAllocSize(AT))
+ if (SSPBufferSize <= TLI->getDataLayout()->getTypeAllocSize(AT))
return true;
}
@@ -228,13 +241,14 @@ bool StackProtector::RequiresStackProtector() {
if (const ConstantInt *CI =
dyn_cast<ConstantInt>(AI->getArraySize())) {
- unsigned BufferSize = TLI->getTargetMachine().Options.SSPBufferSize;
- if (CI->getLimitedValue(BufferSize) >= BufferSize)
+ if (CI->getLimitedValue(SSPBufferSize) >= SSPBufferSize)
// A call to alloca with size >= SSPBufferSize requires
// stack protectors.
return true;
- } else // A call to alloca with a variable size requires protectors.
+ } else {
+ // A call to alloca with a variable size requires protectors.
return true;
+ }
}
if (ContainsProtectableArray(AI->getAllocatedType(), Strong))
@@ -251,6 +265,46 @@ bool StackProtector::RequiresStackProtector() {
return false;
}
+/// Insert code into the entry block that stores the __stack_chk_guard
+/// variable onto the stack:
+///
+/// entry:
+/// StackGuardSlot = alloca i8*
+/// StackGuard = load __stack_chk_guard
+/// call void @llvm.stackprotect.create(StackGuard, StackGuardSlot)
+///
+static void CreatePrologue(Function *F, Module *M, ReturnInst *RI,
+ const TargetLoweringBase *TLI, const Triple &Trip,
+ AllocaInst *&AI, Value *&StackGuardVar) {
+ PointerType *PtrTy = Type::getInt8PtrTy(RI->getContext());
+ unsigned AddressSpace, Offset;
+ if (TLI->getStackCookieLocation(AddressSpace, Offset)) {
+ Constant *OffsetVal =
+ ConstantInt::get(Type::getInt32Ty(RI->getContext()), Offset);
+
+ 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);
+ }
+
+ BasicBlock &Entry = F->getEntryBlock();
+ Instruction *InsPt = &Entry.front();
+
+ AI = new AllocaInst(PtrTy, "StackGuardSlot", InsPt);
+ LoadInst *LI = new LoadInst(StackGuardVar, "StackGuard", false, InsPt);
+
+ Value *Args[] = { LI, AI };
+ CallInst::
+ Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector),
+ Args, "", InsPt);
+}
+
/// InsertStackProtectors - Insert code into the prologue and epilogue of the
/// function.
///
@@ -269,41 +323,7 @@ bool StackProtector::InsertStackProtectors() {
if (!RI) continue;
if (!FailBB) {
- // Insert code into the entry block that stores the __stack_chk_guard
- // variable onto the stack:
- //
- // entry:
- // StackGuardSlot = alloca i8*
- // StackGuard = load __stack_chk_guard
- // call void @llvm.stackprotect.create(StackGuard, StackGuardSlot)
- //
- PointerType *PtrTy = Type::getInt8PtrTy(RI->getContext());
- unsigned AddressSpace, Offset;
- if (TLI->getStackCookieLocation(AddressSpace, Offset)) {
- Constant *OffsetVal =
- ConstantInt::get(Type::getInt32Ty(RI->getContext()), Offset);
-
- 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);
- }
-
- BasicBlock &Entry = F->getEntryBlock();
- Instruction *InsPt = &Entry.front();
-
- AI = new AllocaInst(PtrTy, "StackGuardSlot", InsPt);
- LoadInst *LI = new LoadInst(StackGuardVar, "StackGuard", false, InsPt);
-
- Value *Args[] = { LI, AI };
- CallInst::
- Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector),
- Args, "", InsPt);
-
+ CreatePrologue(F, M, RI, TLI, Trip, AI, StackGuardVar);
// Create the basic block to jump to when the guard check fails.
FailBB = CreateFailBB();
}
generated by cgit v1.1 at 2025-07-04 20:13:32 +0000