[llvm] r258942 - Move SafeStack to CodeGen.
Benjamin Kramer via llvm-commits
llvm-commits at lists.llvm.org
Wed Jan 27 08:53:42 PST 2016
Author: d0k
Date: Wed Jan 27 10:53:42 2016
New Revision: 258942
URL: http://llvm.org/viewvc/llvm-project?rev=258942&view=rev
Log:
Move SafeStack to CodeGen.
It depends on the target machinery, that's not available for
instrumentation passes.
Added:
llvm/trunk/lib/CodeGen/SafeStack.cpp
- copied, changed from r258941, llvm/trunk/lib/Transforms/Instrumentation/SafeStack.cpp
Removed:
llvm/trunk/lib/Transforms/Instrumentation/SafeStack.cpp
Modified:
llvm/trunk/include/llvm/CodeGen/Passes.h
llvm/trunk/include/llvm/Transforms/Instrumentation.h
llvm/trunk/lib/CodeGen/CMakeLists.txt
llvm/trunk/lib/CodeGen/CodeGen.cpp
llvm/trunk/lib/Transforms/Instrumentation/CMakeLists.txt
llvm/trunk/lib/Transforms/Instrumentation/Instrumentation.cpp
llvm/trunk/tools/opt/opt.cpp
Modified: llvm/trunk/include/llvm/CodeGen/Passes.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/Passes.h?rev=258942&r1=258941&r2=258942&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/Passes.h (original)
+++ llvm/trunk/include/llvm/CodeGen/Passes.h Wed Jan 27 10:53:42 2016
@@ -667,6 +667,10 @@ namespace llvm {
Pass *createGlobalMergePass(const TargetMachine *TM, unsigned MaximalOffset,
bool OnlyOptimizeForSize = false,
bool MergeExternalByDefault = false);
+
+ /// This pass splits the stack into a safe stack and an unsafe stack to
+ /// protect against stack-based overflow vulnerabilities.
+ FunctionPass *createSafeStackPass(const TargetMachine *TM = nullptr);
} // End llvm namespace
/// Target machine pass initializer for passes with dependencies. Use with
Modified: llvm/trunk/include/llvm/Transforms/Instrumentation.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Instrumentation.h?rev=258942&r1=258941&r2=258942&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Instrumentation.h (original)
+++ llvm/trunk/include/llvm/Transforms/Instrumentation.h Wed Jan 27 10:53:42 2016
@@ -150,10 +150,6 @@ inline ModulePass *createDataFlowSanitiz
// checking on loads, stores, and other memory intrinsics.
FunctionPass *createBoundsCheckingPass();
-/// \brief This pass splits the stack into a safe stack and an unsafe stack to
-/// protect against stack-based overflow vulnerabilities.
-FunctionPass *createSafeStackPass(const TargetMachine *TM = nullptr);
-
/// \brief Calculate what to divide by to scale counts.
///
/// Given the maximum count, calculate a divisor that will scale all the
Modified: llvm/trunk/lib/CodeGen/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CMakeLists.txt?rev=258942&r1=258941&r2=258942&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CMakeLists.txt (original)
+++ llvm/trunk/lib/CodeGen/CMakeLists.txt Wed Jan 27 10:53:42 2016
@@ -16,15 +16,14 @@ add_llvm_library(LLVMCodeGen
CodeGen.cpp
CodeGenPrepare.cpp
CriticalAntiDepBreaker.cpp
- DFAPacketizer.cpp
DeadMachineInstructionElim.cpp
+ DFAPacketizer.cpp
DwarfEHPrepare.cpp
EarlyIfConversion.cpp
EdgeBundles.cpp
ExecutionDepsFix.cpp
ExpandISelPseudos.cpp
ExpandPostRAPseudos.cpp
- LiveDebugValues.cpp
FaultMaps.cpp
FuncletLayout.cpp
GCMetadata.cpp
@@ -38,57 +37,58 @@ add_llvm_library(LLVMCodeGen
InterferenceCache.cpp
InterleavedAccessPass.cpp
IntrinsicLowering.cpp
- LLVMTargetMachine.cpp
LatencyPriorityQueue.cpp
LexicalScopes.cpp
+ LiveDebugValues.cpp
LiveDebugVariables.cpp
- LiveInterval.cpp
LiveIntervalAnalysis.cpp
+ LiveInterval.cpp
LiveIntervalUnion.cpp
+ LivePhysRegs.cpp
LiveRangeCalc.cpp
LiveRangeEdit.cpp
LiveRegMatrix.cpp
- LivePhysRegs.cpp
LiveStackAnalysis.cpp
LiveVariables.cpp
+ LLVMTargetMachine.cpp
LocalStackSlotAllocation.cpp
LowerEmuTLS.cpp
MachineBasicBlock.cpp
MachineBlockFrequencyInfo.cpp
MachineBlockPlacement.cpp
MachineBranchProbabilityInfo.cpp
- MachineCSE.cpp
MachineCombiner.cpp
MachineCopyPropagation.cpp
- MachineDominators.cpp
+ MachineCSE.cpp
MachineDominanceFrontier.cpp
- MachineFunction.cpp
+ MachineDominators.cpp
MachineFunctionAnalysis.cpp
+ MachineFunction.cpp
MachineFunctionPass.cpp
MachineFunctionPrinterPass.cpp
- MachineInstr.cpp
MachineInstrBundle.cpp
+ MachineInstr.cpp
MachineLICM.cpp
MachineLoopInfo.cpp
MachineModuleInfo.cpp
MachineModuleInfoImpls.cpp
MachinePassRegistry.cpp
MachinePostDominators.cpp
- MachineRegisterInfo.cpp
MachineRegionInfo.cpp
- MachineSSAUpdater.cpp
+ MachineRegisterInfo.cpp
MachineScheduler.cpp
MachineSink.cpp
+ MachineSSAUpdater.cpp
MachineTraceMetrics.cpp
MachineVerifier.cpp
MIRPrinter.cpp
MIRPrintingPass.cpp
OptimizePHIs.cpp
- PHIElimination.cpp
- PHIEliminationUtils.cpp
ParallelCG.cpp
Passes.cpp
PeepholeOptimizer.cpp
+ PHIElimination.cpp
+ PHIEliminationUtils.cpp
PostRASchedulerList.cpp
ProcessImplicitDefs.cpp
PrologEpilogInserter.cpp
@@ -102,21 +102,22 @@ add_llvm_library(LLVMCodeGen
RegisterCoalescer.cpp
RegisterPressure.cpp
RegisterScavenging.cpp
+ SafeStack.cpp
ScheduleDAG.cpp
ScheduleDAGInstrs.cpp
ScheduleDAGPrinter.cpp
ScoreboardHazardRecognizer.cpp
- ShrinkWrap.cpp
ShadowStackGCLowering.cpp
+ ShrinkWrap.cpp
SjLjEHPrepare.cpp
SlotIndexes.cpp
SpillPlacement.cpp
SplitKit.cpp
StackColoring.cpp
- StackProtector.cpp
- StackSlotColoring.cpp
StackMapLivenessAnalysis.cpp
StackMaps.cpp
+ StackProtector.cpp
+ StackSlotColoring.cpp
TailDuplication.cpp
TargetFrameLoweringImpl.cpp
TargetInstrInfo.cpp
Modified: llvm/trunk/lib/CodeGen/CodeGen.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CodeGen.cpp?rev=258942&r1=258941&r2=258942&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CodeGen.cpp (original)
+++ llvm/trunk/lib/CodeGen/CodeGen.cpp Wed Jan 27 10:53:42 2016
@@ -68,6 +68,7 @@ void llvm::initializeCodeGen(PassRegistr
initializeStackColoringPass(Registry);
initializeStackMapLivenessPass(Registry);
initializeLiveDebugValuesPass(Registry);
+ initializeSafeStackPass(Registry);
initializeStackProtectorPass(Registry);
initializeStackSlotColoringPass(Registry);
initializeTailDuplicatePassPass(Registry);
Copied: llvm/trunk/lib/CodeGen/SafeStack.cpp (from r258941, llvm/trunk/lib/Transforms/Instrumentation/SafeStack.cpp)
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SafeStack.cpp?p2=llvm/trunk/lib/CodeGen/SafeStack.cpp&p1=llvm/trunk/lib/Transforms/Instrumentation/SafeStack.cpp&r1=258941&r2=258942&rev=258942&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/SafeStack.cpp (original)
+++ llvm/trunk/lib/CodeGen/SafeStack.cpp Wed Jan 27 10:53:42 2016
@@ -15,22 +15,22 @@
//
//===----------------------------------------------------------------------===//
-#include "llvm/Transforms/Instrumentation.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/Constants.h"
+#include "llvm/IR/DIBuilder.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
-#include "llvm/IR/DIBuilder.h"
#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
-#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
Modified: llvm/trunk/lib/Transforms/Instrumentation/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/CMakeLists.txt?rev=258942&r1=258941&r2=258942&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/CMakeLists.txt (original)
+++ llvm/trunk/lib/Transforms/Instrumentation/CMakeLists.txt Wed Jan 27 10:53:42 2016
@@ -7,7 +7,6 @@ add_llvm_library(LLVMInstrumentation
Instrumentation.cpp
InstrProfiling.cpp
PGOInstrumentation.cpp
- SafeStack.cpp
SanitizerCoverage.cpp
ThreadSanitizer.cpp
Modified: llvm/trunk/lib/Transforms/Instrumentation/Instrumentation.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/Instrumentation.cpp?rev=258942&r1=258941&r2=258942&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/Instrumentation.cpp (original)
+++ llvm/trunk/lib/Transforms/Instrumentation/Instrumentation.cpp Wed Jan 27 10:53:42 2016
@@ -67,7 +67,6 @@ void llvm::initializeInstrumentation(Pas
initializeThreadSanitizerPass(Registry);
initializeSanitizerCoverageModulePass(Registry);
initializeDataFlowSanitizerPass(Registry);
- initializeSafeStackPass(Registry);
}
/// LLVMInitializeInstrumentation - C binding for
Removed: llvm/trunk/lib/Transforms/Instrumentation/SafeStack.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/SafeStack.cpp?rev=258941&view=auto
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/SafeStack.cpp (original)
+++ llvm/trunk/lib/Transforms/Instrumentation/SafeStack.cpp (removed)
@@ -1,760 +0,0 @@
-//===-- SafeStack.cpp - Safe Stack Insertion ------------------------------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This pass splits the stack into the safe stack (kept as-is for LLVM backend)
-// and the unsafe stack (explicitly allocated and managed through the runtime
-// support library).
-//
-// http://clang.llvm.org/docs/SafeStack.html
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Transforms/Instrumentation.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/Triple.h"
-#include "llvm/Analysis/ScalarEvolution.h"
-#include "llvm/Analysis/ScalarEvolutionExpressions.h"
-#include "llvm/CodeGen/Passes.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/DataLayout.h"
-#include "llvm/IR/DerivedTypes.h"
-#include "llvm/IR/DIBuilder.h"
-#include "llvm/IR/Function.h"
-#include "llvm/IR/InstIterator.h"
-#include "llvm/IR/Instructions.h"
-#include "llvm/IR/IntrinsicInst.h"
-#include "llvm/IR/Intrinsics.h"
-#include "llvm/IR/IRBuilder.h"
-#include "llvm/IR/Module.h"
-#include "llvm/Pass.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/Format.h"
-#include "llvm/Support/MathExtras.h"
-#include "llvm/Support/raw_os_ostream.h"
-#include "llvm/Target/TargetLowering.h"
-#include "llvm/Target/TargetSubtargetInfo.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Transforms/Utils/ModuleUtils.h"
-
-using namespace llvm;
-
-#define DEBUG_TYPE "safestack"
-
-enum UnsafeStackPtrStorageVal { ThreadLocalUSP, SingleThreadUSP };
-
-static cl::opt<UnsafeStackPtrStorageVal> USPStorage("safe-stack-usp-storage",
- cl::Hidden, cl::init(ThreadLocalUSP),
- cl::desc("Type of storage for the unsafe stack pointer"),
- cl::values(clEnumValN(ThreadLocalUSP, "thread-local",
- "Thread-local storage"),
- clEnumValN(SingleThreadUSP, "single-thread",
- "Non-thread-local storage"),
- clEnumValEnd));
-
-namespace llvm {
-
-STATISTIC(NumFunctions, "Total number of functions");
-STATISTIC(NumUnsafeStackFunctions, "Number of functions with unsafe stack");
-STATISTIC(NumUnsafeStackRestorePointsFunctions,
- "Number of functions that use setjmp or exceptions");
-
-STATISTIC(NumAllocas, "Total number of allocas");
-STATISTIC(NumUnsafeStaticAllocas, "Number of unsafe static allocas");
-STATISTIC(NumUnsafeDynamicAllocas, "Number of unsafe dynamic allocas");
-STATISTIC(NumUnsafeByValArguments, "Number of unsafe byval arguments");
-STATISTIC(NumUnsafeStackRestorePoints, "Number of setjmps and landingpads");
-
-} // namespace llvm
-
-namespace {
-
-/// Rewrite an SCEV expression for a memory access address to an expression that
-/// represents offset from the given alloca.
-///
-/// The implementation simply replaces all mentions of the alloca with zero.
-class AllocaOffsetRewriter : public SCEVRewriteVisitor<AllocaOffsetRewriter> {
- const Value *AllocaPtr;
-
-public:
- AllocaOffsetRewriter(ScalarEvolution &SE, const Value *AllocaPtr)
- : SCEVRewriteVisitor(SE), AllocaPtr(AllocaPtr) {}
-
- const SCEV *visitUnknown(const SCEVUnknown *Expr) {
- if (Expr->getValue() == AllocaPtr)
- return SE.getZero(Expr->getType());
- return Expr;
- }
-};
-
-/// The SafeStack pass splits the stack of each function into the safe
-/// stack, which is only accessed through memory safe dereferences (as
-/// determined statically), and the unsafe stack, which contains all
-/// local variables that are accessed in ways that we can't prove to
-/// be safe.
-class SafeStack : public FunctionPass {
- const TargetMachine *TM;
- const TargetLoweringBase *TL;
- const DataLayout *DL;
- ScalarEvolution *SE;
-
- Type *StackPtrTy;
- Type *IntPtrTy;
- Type *Int32Ty;
- Type *Int8Ty;
-
- Value *UnsafeStackPtr = nullptr;
-
- /// Unsafe stack alignment. Each stack frame must ensure that the stack is
- /// aligned to this value. We need to re-align the unsafe stack if the
- /// alignment of any object on the stack exceeds this value.
- ///
- /// 16 seems like a reasonable upper bound on the alignment of objects that we
- /// might expect to appear on the stack on most common targets.
- enum { StackAlignment = 16 };
-
- /// \brief Build a value representing a pointer to the unsafe stack pointer.
- Value *getOrCreateUnsafeStackPtr(IRBuilder<> &IRB, Function &F);
-
- /// \brief Find all static allocas, dynamic allocas, return instructions and
- /// stack restore points (exception unwind blocks and setjmp calls) in the
- /// given function and append them to the respective vectors.
- void findInsts(Function &F, SmallVectorImpl<AllocaInst *> &StaticAllocas,
- SmallVectorImpl<AllocaInst *> &DynamicAllocas,
- SmallVectorImpl<Argument *> &ByValArguments,
- SmallVectorImpl<ReturnInst *> &Returns,
- SmallVectorImpl<Instruction *> &StackRestorePoints);
-
- /// \brief Calculate the allocation size of a given alloca. Returns 0 if the
- /// size can not be statically determined.
- uint64_t getStaticAllocaAllocationSize(const AllocaInst* AI);
-
- /// \brief Allocate space for all static allocas in \p StaticAllocas,
- /// replace allocas with pointers into the unsafe stack and generate code to
- /// restore the stack pointer before all return instructions in \p Returns.
- ///
- /// \returns A pointer to the top of the unsafe stack after all unsafe static
- /// allocas are allocated.
- Value *moveStaticAllocasToUnsafeStack(IRBuilder<> &IRB, Function &F,
- ArrayRef<AllocaInst *> StaticAllocas,
- ArrayRef<Argument *> ByValArguments,
- ArrayRef<ReturnInst *> Returns);
-
- /// \brief Generate code to restore the stack after all stack restore points
- /// in \p StackRestorePoints.
- ///
- /// \returns A local variable in which to maintain the dynamic top of the
- /// unsafe stack if needed.
- AllocaInst *
- createStackRestorePoints(IRBuilder<> &IRB, Function &F,
- ArrayRef<Instruction *> StackRestorePoints,
- Value *StaticTop, bool NeedDynamicTop);
-
- /// \brief Replace all allocas in \p DynamicAllocas with code to allocate
- /// space dynamically on the unsafe stack and store the dynamic unsafe stack
- /// top to \p DynamicTop if non-null.
- void moveDynamicAllocasToUnsafeStack(Function &F, Value *UnsafeStackPtr,
- AllocaInst *DynamicTop,
- ArrayRef<AllocaInst *> DynamicAllocas);
-
- bool IsSafeStackAlloca(const Value *AllocaPtr, uint64_t AllocaSize);
-
- bool IsMemIntrinsicSafe(const MemIntrinsic *MI, const Use &U,
- const Value *AllocaPtr, uint64_t AllocaSize);
- bool IsAccessSafe(Value *Addr, uint64_t Size, const Value *AllocaPtr,
- uint64_t AllocaSize);
-
-public:
- static char ID; // Pass identification, replacement for typeid.
- SafeStack(const TargetMachine *TM)
- : FunctionPass(ID), TM(TM), TL(nullptr), DL(nullptr) {
- initializeSafeStackPass(*PassRegistry::getPassRegistry());
- }
- SafeStack() : SafeStack(nullptr) {}
-
- void getAnalysisUsage(AnalysisUsage &AU) const override {
- AU.addRequired<ScalarEvolutionWrapperPass>();
- }
-
- bool doInitialization(Module &M) override {
- DL = &M.getDataLayout();
-
- StackPtrTy = Type::getInt8PtrTy(M.getContext());
- IntPtrTy = DL->getIntPtrType(M.getContext());
- Int32Ty = Type::getInt32Ty(M.getContext());
- Int8Ty = Type::getInt8Ty(M.getContext());
-
- return false;
- }
-
- bool runOnFunction(Function &F) override;
-}; // class SafeStack
-
-uint64_t SafeStack::getStaticAllocaAllocationSize(const AllocaInst* AI) {
- uint64_t Size = DL->getTypeAllocSize(AI->getAllocatedType());
- if (AI->isArrayAllocation()) {
- auto C = dyn_cast<ConstantInt>(AI->getArraySize());
- if (!C)
- return 0;
- Size *= C->getZExtValue();
- }
- return Size;
-}
-
-bool SafeStack::IsAccessSafe(Value *Addr, uint64_t AccessSize,
- const Value *AllocaPtr, uint64_t AllocaSize) {
- AllocaOffsetRewriter Rewriter(*SE, AllocaPtr);
- const SCEV *Expr = Rewriter.visit(SE->getSCEV(Addr));
-
- uint64_t BitWidth = SE->getTypeSizeInBits(Expr->getType());
- ConstantRange AccessStartRange = SE->getUnsignedRange(Expr);
- ConstantRange SizeRange =
- ConstantRange(APInt(BitWidth, 0), APInt(BitWidth, AccessSize));
- ConstantRange AccessRange = AccessStartRange.add(SizeRange);
- ConstantRange AllocaRange =
- ConstantRange(APInt(BitWidth, 0), APInt(BitWidth, AllocaSize));
- bool Safe = AllocaRange.contains(AccessRange);
-
- DEBUG(dbgs() << "[SafeStack] "
- << (isa<AllocaInst>(AllocaPtr) ? "Alloca " : "ByValArgument ")
- << *AllocaPtr << "\n"
- << " Access " << *Addr << "\n"
- << " SCEV " << *Expr
- << " U: " << SE->getUnsignedRange(Expr)
- << ", S: " << SE->getSignedRange(Expr) << "\n"
- << " Range " << AccessRange << "\n"
- << " AllocaRange " << AllocaRange << "\n"
- << " " << (Safe ? "safe" : "unsafe") << "\n");
-
- return Safe;
-}
-
-bool SafeStack::IsMemIntrinsicSafe(const MemIntrinsic *MI, const Use &U,
- const Value *AllocaPtr,
- uint64_t AllocaSize) {
- // All MemIntrinsics have destination address in Arg0 and size in Arg2.
- if (MI->getRawDest() != U) return true;
- const auto *Len = dyn_cast<ConstantInt>(MI->getLength());
- // Non-constant size => unsafe. FIXME: try SCEV getRange.
- if (!Len) return false;
- return IsAccessSafe(U, Len->getZExtValue(), AllocaPtr, AllocaSize);
-}
-
-/// Check whether a given allocation must be put on the safe
-/// stack or not. The function analyzes all uses of AI and checks whether it is
-/// only accessed in a memory safe way (as decided statically).
-bool SafeStack::IsSafeStackAlloca(const Value *AllocaPtr, uint64_t AllocaSize) {
- // Go through all uses of this alloca and check whether all accesses to the
- // allocated object are statically known to be memory safe and, hence, the
- // object can be placed on the safe stack.
- SmallPtrSet<const Value *, 16> Visited;
- SmallVector<const Value *, 8> WorkList;
- WorkList.push_back(AllocaPtr);
-
- // A DFS search through all uses of the alloca in bitcasts/PHI/GEPs/etc.
- while (!WorkList.empty()) {
- const Value *V = WorkList.pop_back_val();
- for (const Use &UI : V->uses()) {
- auto I = cast<const Instruction>(UI.getUser());
- assert(V == UI.get());
-
- switch (I->getOpcode()) {
- case Instruction::Load: {
- if (!IsAccessSafe(UI, DL->getTypeStoreSize(I->getType()), AllocaPtr,
- AllocaSize))
- return false;
- break;
- }
- case Instruction::VAArg:
- // "va-arg" from a pointer is safe.
- break;
- case Instruction::Store: {
- if (V == I->getOperand(0)) {
- // Stored the pointer - conservatively assume it may be unsafe.
- DEBUG(dbgs() << "[SafeStack] Unsafe alloca: " << *AllocaPtr
- << "\n store of address: " << *I << "\n");
- return false;
- }
-
- if (!IsAccessSafe(UI, DL->getTypeStoreSize(I->getOperand(0)->getType()),
- AllocaPtr, AllocaSize))
- return false;
- break;
- }
- case Instruction::Ret: {
- // Information leak.
- return false;
- }
-
- case Instruction::Call:
- case Instruction::Invoke: {
- ImmutableCallSite CS(I);
-
- if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
- if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
- II->getIntrinsicID() == Intrinsic::lifetime_end)
- continue;
- }
-
- if (const MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I)) {
- if (!IsMemIntrinsicSafe(MI, UI, AllocaPtr, AllocaSize)) {
- DEBUG(dbgs() << "[SafeStack] Unsafe alloca: " << *AllocaPtr
- << "\n unsafe memintrinsic: " << *I
- << "\n");
- return false;
- }
- continue;
- }
-
- // LLVM 'nocapture' attribute is only set for arguments whose address
- // is not stored, passed around, or used in any other non-trivial way.
- // We assume that passing a pointer to an object as a 'nocapture
- // readnone' argument is safe.
- // FIXME: a more precise solution would require an interprocedural
- // analysis here, which would look at all uses of an argument inside
- // the function being called.
- ImmutableCallSite::arg_iterator B = CS.arg_begin(), E = CS.arg_end();
- for (ImmutableCallSite::arg_iterator A = B; A != E; ++A)
- if (A->get() == V)
- if (!(CS.doesNotCapture(A - B) && (CS.doesNotAccessMemory(A - B) ||
- CS.doesNotAccessMemory()))) {
- DEBUG(dbgs() << "[SafeStack] Unsafe alloca: " << *AllocaPtr
- << "\n unsafe call: " << *I << "\n");
- return false;
- }
- continue;
- }
-
- default:
- if (Visited.insert(I).second)
- WorkList.push_back(cast<const Instruction>(I));
- }
- }
- }
-
- // All uses of the alloca are safe, we can place it on the safe stack.
- return true;
-}
-
-Value *SafeStack::getOrCreateUnsafeStackPtr(IRBuilder<> &IRB, Function &F) {
- // Check if there is a target-specific location for the unsafe stack pointer.
- if (TL)
- if (Value *V = TL->getSafeStackPointerLocation(IRB))
- return V;
-
- // Otherwise, assume the target links with compiler-rt, which provides a
- // thread-local variable with a magic name.
- Module &M = *F.getParent();
- const char *UnsafeStackPtrVar = "__safestack_unsafe_stack_ptr";
- auto UnsafeStackPtr =
- dyn_cast_or_null<GlobalVariable>(M.getNamedValue(UnsafeStackPtrVar));
-
- bool UseTLS = USPStorage == ThreadLocalUSP;
-
- if (!UnsafeStackPtr) {
- auto TLSModel = UseTLS ?
- GlobalValue::InitialExecTLSModel :
- GlobalValue::NotThreadLocal;
- // The global variable is not defined yet, define it ourselves.
- // We use the initial-exec TLS model because we do not support the
- // variable living anywhere other than in the main executable.
- UnsafeStackPtr = new GlobalVariable(
- M, StackPtrTy, false, GlobalValue::ExternalLinkage, nullptr,
- UnsafeStackPtrVar, nullptr, TLSModel);
- } else {
- // The variable exists, check its type and attributes.
- if (UnsafeStackPtr->getValueType() != StackPtrTy)
- report_fatal_error(Twine(UnsafeStackPtrVar) + " must have void* type");
- if (UseTLS != UnsafeStackPtr->isThreadLocal())
- report_fatal_error(Twine(UnsafeStackPtrVar) + " must " +
- (UseTLS ? "" : "not ") + "be thread-local");
- }
- return UnsafeStackPtr;
-}
-
-void SafeStack::findInsts(Function &F,
- SmallVectorImpl<AllocaInst *> &StaticAllocas,
- SmallVectorImpl<AllocaInst *> &DynamicAllocas,
- SmallVectorImpl<Argument *> &ByValArguments,
- SmallVectorImpl<ReturnInst *> &Returns,
- SmallVectorImpl<Instruction *> &StackRestorePoints) {
- for (Instruction &I : instructions(&F)) {
- if (auto AI = dyn_cast<AllocaInst>(&I)) {
- ++NumAllocas;
-
- uint64_t Size = getStaticAllocaAllocationSize(AI);
- if (IsSafeStackAlloca(AI, Size))
- continue;
-
- if (AI->isStaticAlloca()) {
- ++NumUnsafeStaticAllocas;
- StaticAllocas.push_back(AI);
- } else {
- ++NumUnsafeDynamicAllocas;
- DynamicAllocas.push_back(AI);
- }
- } else if (auto RI = dyn_cast<ReturnInst>(&I)) {
- Returns.push_back(RI);
- } else if (auto CI = dyn_cast<CallInst>(&I)) {
- // setjmps require stack restore.
- if (CI->getCalledFunction() && CI->canReturnTwice())
- StackRestorePoints.push_back(CI);
- } else if (auto LP = dyn_cast<LandingPadInst>(&I)) {
- // Exception landing pads require stack restore.
- StackRestorePoints.push_back(LP);
- } else if (auto II = dyn_cast<IntrinsicInst>(&I)) {
- if (II->getIntrinsicID() == Intrinsic::gcroot)
- llvm::report_fatal_error(
- "gcroot intrinsic not compatible with safestack attribute");
- }
- }
- for (Argument &Arg : F.args()) {
- if (!Arg.hasByValAttr())
- continue;
- uint64_t Size =
- DL->getTypeStoreSize(Arg.getType()->getPointerElementType());
- if (IsSafeStackAlloca(&Arg, Size))
- continue;
-
- ++NumUnsafeByValArguments;
- ByValArguments.push_back(&Arg);
- }
-}
-
-AllocaInst *
-SafeStack::createStackRestorePoints(IRBuilder<> &IRB, Function &F,
- ArrayRef<Instruction *> StackRestorePoints,
- Value *StaticTop, bool NeedDynamicTop) {
- if (StackRestorePoints.empty())
- return nullptr;
-
- // We need the current value of the shadow stack pointer to restore
- // after longjmp or exception catching.
-
- // FIXME: On some platforms this could be handled by the longjmp/exception
- // runtime itself.
-
- AllocaInst *DynamicTop = nullptr;
- if (NeedDynamicTop)
- // If we also have dynamic alloca's, the stack pointer value changes
- // throughout the function. For now we store it in an alloca.
- DynamicTop = IRB.CreateAlloca(StackPtrTy, /*ArraySize=*/nullptr,
- "unsafe_stack_dynamic_ptr");
-
- if (!StaticTop)
- // We need the original unsafe stack pointer value, even if there are
- // no unsafe static allocas.
- StaticTop = IRB.CreateLoad(UnsafeStackPtr, false, "unsafe_stack_ptr");
-
- if (NeedDynamicTop)
- IRB.CreateStore(StaticTop, DynamicTop);
-
- // Restore current stack pointer after longjmp/exception catch.
- for (Instruction *I : StackRestorePoints) {
- ++NumUnsafeStackRestorePoints;
-
- IRB.SetInsertPoint(I->getNextNode());
- Value *CurrentTop = DynamicTop ? IRB.CreateLoad(DynamicTop) : StaticTop;
- IRB.CreateStore(CurrentTop, UnsafeStackPtr);
- }
-
- return DynamicTop;
-}
-
-Value *SafeStack::moveStaticAllocasToUnsafeStack(
- IRBuilder<> &IRB, Function &F, ArrayRef<AllocaInst *> StaticAllocas,
- ArrayRef<Argument *> ByValArguments, ArrayRef<ReturnInst *> Returns) {
- if (StaticAllocas.empty() && ByValArguments.empty())
- return nullptr;
-
- DIBuilder DIB(*F.getParent());
-
- // We explicitly compute and set the unsafe stack layout for all unsafe
- // static alloca instructions. We save the unsafe "base pointer" in the
- // prologue into a local variable and restore it in the epilogue.
-
- // Load the current stack pointer (we'll also use it as a base pointer).
- // FIXME: use a dedicated register for it ?
- Instruction *BasePointer =
- IRB.CreateLoad(UnsafeStackPtr, false, "unsafe_stack_ptr");
- assert(BasePointer->getType() == StackPtrTy);
-
- for (ReturnInst *RI : Returns) {
- IRB.SetInsertPoint(RI);
- IRB.CreateStore(BasePointer, UnsafeStackPtr);
- }
-
- // Compute maximum alignment among static objects on the unsafe stack.
- unsigned MaxAlignment = 0;
- for (Argument *Arg : ByValArguments) {
- Type *Ty = Arg->getType()->getPointerElementType();
- unsigned Align = std::max((unsigned)DL->getPrefTypeAlignment(Ty),
- Arg->getParamAlignment());
- if (Align > MaxAlignment)
- MaxAlignment = Align;
- }
- for (AllocaInst *AI : StaticAllocas) {
- Type *Ty = AI->getAllocatedType();
- unsigned Align =
- std::max((unsigned)DL->getPrefTypeAlignment(Ty), AI->getAlignment());
- if (Align > MaxAlignment)
- MaxAlignment = Align;
- }
-
- if (MaxAlignment > StackAlignment) {
- // Re-align the base pointer according to the max requested alignment.
- assert(isPowerOf2_32(MaxAlignment));
- IRB.SetInsertPoint(BasePointer->getNextNode());
- BasePointer = cast<Instruction>(IRB.CreateIntToPtr(
- IRB.CreateAnd(IRB.CreatePtrToInt(BasePointer, IntPtrTy),
- ConstantInt::get(IntPtrTy, ~uint64_t(MaxAlignment - 1))),
- StackPtrTy));
- }
-
- int64_t StaticOffset = 0; // Current stack top.
- IRB.SetInsertPoint(BasePointer->getNextNode());
-
- for (Argument *Arg : ByValArguments) {
- Type *Ty = Arg->getType()->getPointerElementType();
-
- uint64_t Size = DL->getTypeStoreSize(Ty);
- if (Size == 0)
- Size = 1; // Don't create zero-sized stack objects.
-
- // Ensure the object is properly aligned.
- unsigned Align = std::max((unsigned)DL->getPrefTypeAlignment(Ty),
- Arg->getParamAlignment());
-
- // Add alignment.
- // NOTE: we ensure that BasePointer itself is aligned to >= Align.
- StaticOffset += Size;
- StaticOffset = alignTo(StaticOffset, Align);
-
- Value *Off = IRB.CreateGEP(BasePointer, // BasePointer is i8*
- ConstantInt::get(Int32Ty, -StaticOffset));
- Value *NewArg = IRB.CreateBitCast(Off, Arg->getType(),
- Arg->getName() + ".unsafe-byval");
-
- // Replace alloc with the new location.
- replaceDbgDeclare(Arg, BasePointer, BasePointer->getNextNode(), DIB,
- /*Deref=*/true, -StaticOffset);
- Arg->replaceAllUsesWith(NewArg);
- IRB.SetInsertPoint(cast<Instruction>(NewArg)->getNextNode());
- IRB.CreateMemCpy(Off, Arg, Size, Arg->getParamAlignment());
- }
-
- // Allocate space for every unsafe static AllocaInst on the unsafe stack.
- for (AllocaInst *AI : StaticAllocas) {
- IRB.SetInsertPoint(AI);
-
- Type *Ty = AI->getAllocatedType();
- uint64_t Size = getStaticAllocaAllocationSize(AI);
- if (Size == 0)
- Size = 1; // Don't create zero-sized stack objects.
-
- // Ensure the object is properly aligned.
- unsigned Align =
- std::max((unsigned)DL->getPrefTypeAlignment(Ty), AI->getAlignment());
-
- // Add alignment.
- // NOTE: we ensure that BasePointer itself is aligned to >= Align.
- StaticOffset += Size;
- StaticOffset = alignTo(StaticOffset, Align);
-
- Value *Off = IRB.CreateGEP(BasePointer, // BasePointer is i8*
- ConstantInt::get(Int32Ty, -StaticOffset));
- Value *NewAI = IRB.CreateBitCast(Off, AI->getType(), AI->getName());
- if (AI->hasName() && isa<Instruction>(NewAI))
- cast<Instruction>(NewAI)->takeName(AI);
-
- // Replace alloc with the new location.
- replaceDbgDeclareForAlloca(AI, BasePointer, DIB, /*Deref=*/true, -StaticOffset);
- AI->replaceAllUsesWith(NewAI);
- AI->eraseFromParent();
- }
-
- // Re-align BasePointer so that our callees would see it aligned as
- // expected.
- // FIXME: no need to update BasePointer in leaf functions.
- StaticOffset = alignTo(StaticOffset, StackAlignment);
-
- // Update shadow stack pointer in the function epilogue.
- IRB.SetInsertPoint(BasePointer->getNextNode());
-
- Value *StaticTop =
- IRB.CreateGEP(BasePointer, ConstantInt::get(Int32Ty, -StaticOffset),
- "unsafe_stack_static_top");
- IRB.CreateStore(StaticTop, UnsafeStackPtr);
- return StaticTop;
-}
-
-void SafeStack::moveDynamicAllocasToUnsafeStack(
- Function &F, Value *UnsafeStackPtr, AllocaInst *DynamicTop,
- ArrayRef<AllocaInst *> DynamicAllocas) {
- DIBuilder DIB(*F.getParent());
-
- for (AllocaInst *AI : DynamicAllocas) {
- IRBuilder<> IRB(AI);
-
- // Compute the new SP value (after AI).
- Value *ArraySize = AI->getArraySize();
- if (ArraySize->getType() != IntPtrTy)
- ArraySize = IRB.CreateIntCast(ArraySize, IntPtrTy, false);
-
- Type *Ty = AI->getAllocatedType();
- uint64_t TySize = DL->getTypeAllocSize(Ty);
- Value *Size = IRB.CreateMul(ArraySize, ConstantInt::get(IntPtrTy, TySize));
-
- Value *SP = IRB.CreatePtrToInt(IRB.CreateLoad(UnsafeStackPtr), IntPtrTy);
- SP = IRB.CreateSub(SP, Size);
-
- // Align the SP value to satisfy the AllocaInst, type and stack alignments.
- unsigned Align = std::max(
- std::max((unsigned)DL->getPrefTypeAlignment(Ty), AI->getAlignment()),
- (unsigned)StackAlignment);
-
- assert(isPowerOf2_32(Align));
- Value *NewTop = IRB.CreateIntToPtr(
- IRB.CreateAnd(SP, ConstantInt::get(IntPtrTy, ~uint64_t(Align - 1))),
- StackPtrTy);
-
- // Save the stack pointer.
- IRB.CreateStore(NewTop, UnsafeStackPtr);
- if (DynamicTop)
- IRB.CreateStore(NewTop, DynamicTop);
-
- Value *NewAI = IRB.CreatePointerCast(NewTop, AI->getType());
- if (AI->hasName() && isa<Instruction>(NewAI))
- NewAI->takeName(AI);
-
- replaceDbgDeclareForAlloca(AI, NewAI, DIB, /*Deref=*/true);
- AI->replaceAllUsesWith(NewAI);
- AI->eraseFromParent();
- }
-
- if (!DynamicAllocas.empty()) {
- // Now go through the instructions again, replacing stacksave/stackrestore.
- for (inst_iterator It = inst_begin(&F), Ie = inst_end(&F); It != Ie;) {
- Instruction *I = &*(It++);
- auto II = dyn_cast<IntrinsicInst>(I);
- if (!II)
- continue;
-
- if (II->getIntrinsicID() == Intrinsic::stacksave) {
- IRBuilder<> IRB(II);
- Instruction *LI = IRB.CreateLoad(UnsafeStackPtr);
- LI->takeName(II);
- II->replaceAllUsesWith(LI);
- II->eraseFromParent();
- } else if (II->getIntrinsicID() == Intrinsic::stackrestore) {
- IRBuilder<> IRB(II);
- Instruction *SI = IRB.CreateStore(II->getArgOperand(0), UnsafeStackPtr);
- SI->takeName(II);
- assert(II->use_empty());
- II->eraseFromParent();
- }
- }
- }
-}
-
-bool SafeStack::runOnFunction(Function &F) {
- DEBUG(dbgs() << "[SafeStack] Function: " << F.getName() << "\n");
-
- if (!F.hasFnAttribute(Attribute::SafeStack)) {
- DEBUG(dbgs() << "[SafeStack] safestack is not requested"
- " for this function\n");
- return false;
- }
-
- if (F.isDeclaration()) {
- DEBUG(dbgs() << "[SafeStack] function definition"
- " is not available\n");
- return false;
- }
-
- TL = TM ? TM->getSubtargetImpl(F)->getTargetLowering() : nullptr;
- SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
-
- {
- // Make sure the regular stack protector won't run on this function
- // (safestack attribute takes precedence).
- AttrBuilder B;
- B.addAttribute(Attribute::StackProtect)
- .addAttribute(Attribute::StackProtectReq)
- .addAttribute(Attribute::StackProtectStrong);
- F.removeAttributes(
- AttributeSet::FunctionIndex,
- AttributeSet::get(F.getContext(), AttributeSet::FunctionIndex, B));
- }
-
- ++NumFunctions;
-
- SmallVector<AllocaInst *, 16> StaticAllocas;
- SmallVector<AllocaInst *, 4> DynamicAllocas;
- SmallVector<Argument *, 4> ByValArguments;
- SmallVector<ReturnInst *, 4> Returns;
-
- // Collect all points where stack gets unwound and needs to be restored
- // This is only necessary because the runtime (setjmp and unwind code) is
- // not aware of the unsafe stack and won't unwind/restore it prorerly.
- // To work around this problem without changing the runtime, we insert
- // instrumentation to restore the unsafe stack pointer when necessary.
- SmallVector<Instruction *, 4> StackRestorePoints;
-
- // Find all static and dynamic alloca instructions that must be moved to the
- // unsafe stack, all return instructions and stack restore points.
- findInsts(F, StaticAllocas, DynamicAllocas, ByValArguments, Returns,
- StackRestorePoints);
-
- if (StaticAllocas.empty() && DynamicAllocas.empty() &&
- ByValArguments.empty() && StackRestorePoints.empty())
- return false; // Nothing to do in this function.
-
- if (!StaticAllocas.empty() || !DynamicAllocas.empty() ||
- !ByValArguments.empty())
- ++NumUnsafeStackFunctions; // This function has the unsafe stack.
-
- if (!StackRestorePoints.empty())
- ++NumUnsafeStackRestorePointsFunctions;
-
- IRBuilder<> IRB(&F.front(), F.begin()->getFirstInsertionPt());
- UnsafeStackPtr = getOrCreateUnsafeStackPtr(IRB, F);
-
- // The top of the unsafe stack after all unsafe static allocas are allocated.
- Value *StaticTop = moveStaticAllocasToUnsafeStack(IRB, F, StaticAllocas,
- ByValArguments, Returns);
-
- // Safe stack object that stores the current unsafe stack top. It is updated
- // as unsafe dynamic (non-constant-sized) allocas are allocated and freed.
- // This is only needed if we need to restore stack pointer after longjmp
- // or exceptions, and we have dynamic allocations.
- // FIXME: a better alternative might be to store the unsafe stack pointer
- // before setjmp / invoke instructions.
- AllocaInst *DynamicTop = createStackRestorePoints(
- IRB, F, StackRestorePoints, StaticTop, !DynamicAllocas.empty());
-
- // Handle dynamic allocas.
- moveDynamicAllocasToUnsafeStack(F, UnsafeStackPtr, DynamicTop,
- DynamicAllocas);
-
- DEBUG(dbgs() << "[SafeStack] safestack applied\n");
- return true;
-}
-
-} // anonymous namespace
-
-char SafeStack::ID = 0;
-INITIALIZE_TM_PASS_BEGIN(SafeStack, "safe-stack",
- "Safe Stack instrumentation pass", false, false)
-INITIALIZE_TM_PASS_END(SafeStack, "safe-stack",
- "Safe Stack instrumentation pass", false, false)
-
-FunctionPass *llvm::createSafeStackPass(const llvm::TargetMachine *TM) {
- return new SafeStack(TM);
-}
Modified: llvm/trunk/tools/opt/opt.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/opt/opt.cpp?rev=258942&r1=258941&r2=258942&view=diff
==============================================================================
--- llvm/trunk/tools/opt/opt.cpp (original)
+++ llvm/trunk/tools/opt/opt.cpp Wed Jan 27 10:53:42 2016
@@ -329,6 +329,7 @@ int main(int argc, char **argv) {
initializeRewriteSymbolsPass(Registry);
initializeWinEHPreparePass(Registry);
initializeDwarfEHPreparePass(Registry);
+ initializeSafeStackPass(Registry);
initializeSjLjEHPreparePass(Registry);
#ifdef LINK_POLLY_INTO_TOOLS
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