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[stackprotector] Refactor the StackProtector pass from a single .cpp file into StackProtector.h and StackProtector.cpp. 

No functionality change.  Future patches will add analysis which will be used
in other passes (PEI, StackSlot).  The end goal is to support ssp-strong stack
layout rules.

WIP.

Differential Revision: http://llvm-reviews.chandlerc.com/D1521

llvm-svn: 191570
This commit is contained in:
Josh Magee 2013-09-27 21:58:43 +00:00
parent bc654b18bc
commit 8ecfb52388
2 changed files with 98 additions and 70 deletions
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97
llvm/include/llvm/CodeGen/StackProtector.h Normal file
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@ -0,0 +1,97 @@
//===-- StackProtector.h - Stack Protector Insertion ----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass inserts stack protectors into functions which need them. A variable
// with a random value in it is stored onto the stack before the local variables
// are allocated. Upon exiting the block, the stored value is checked. If it's
// changed, then there was some sort of violation and the program aborts.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_STACKPROTECTOR_H
#define LLVM_CODEGEN_STACKPROTECTOR_H
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Pass.h"
#include "llvm/Target/TargetLowering.h"
namespace llvm {
class DominatorTree;
class Function;
class Module;
class PHINode;
class StackProtector : public FunctionPass {
const TargetMachine *TM;
/// TLI - Keep a pointer of a TargetLowering to consult for determining
/// target type sizes.
const TargetLoweringBase *TLI;
const Triple Trip;
Function *F;
Module *M;
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
/// times.
SmallPtrSet<const PHINode*, 16> VisitedPHIs;
/// InsertStackProtectors - Insert code into the prologue and epilogue of
/// the function.
///
/// - The prologue code loads and stores the stack guard onto the stack.
/// - The epilogue checks the value stored in the prologue against the
/// original value. It calls __stack_chk_fail if they differ.
bool InsertStackProtectors();
/// CreateFailBB - Create a basic block to jump to when the stack protector
/// check fails.
BasicBlock *CreateFailBB();
/// ContainsProtectableArray - Check whether the type either is an array or
/// contains an array of sufficient size so that we need stack protectors
/// for it.
bool ContainsProtectableArray(Type *Ty, bool Strong = false,
bool InStruct = false) const;
/// \brief Check whether a stack allocation has its address taken.
bool HasAddressTaken(const Instruction *AI);
/// RequiresStackProtector - Check whether or not this function needs a
/// stack protector based upon the stack protector level.
bool RequiresStackProtector();
public:
static char ID; // Pass identification, replacement for typeid.
StackProtector() : FunctionPass(ID), TM(0), TLI(0), SSPBufferSize(0) {
initializeStackProtectorPass(*PassRegistry::getPassRegistry());
}
StackProtector(const TargetMachine *TM)
: FunctionPass(ID), TM(TM), TLI(0), Trip(TM->getTargetTriple()),
SSPBufferSize(8) {
initializeStackProtectorPass(*PassRegistry::getPassRegistry());
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addPreserved<DominatorTree>();
}
virtual bool runOnFunction(Function &Fn);
};
} // end namespace llvm
#endif // LLVM_CODEGEN_STACKPROTECTOR_H

71
llvm/lib/CodeGen/StackProtector.cpp
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@ -15,11 +15,11 @@
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "stack-protector"
#include "llvm/CodeGen/StackProtector.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Attributes.h"
@ -34,9 +34,7 @@
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetLowering.h"
#include <cstdlib>
using namespace llvm;
@ -48,73 +46,6 @@ static cl::opt<bool>
EnableSelectionDAGSP("enable-selectiondag-sp", cl::init(true),
cl::Hidden);
namespace {
class StackProtector : public FunctionPass {
const TargetMachine *TM;
/// TLI - Keep a pointer of a TargetLowering to consult for determining
/// target type sizes.
const TargetLoweringBase *TLI;
const Triple Trip;
Function *F;
Module *M;
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
/// times.
SmallPtrSet<const PHINode*, 16> VisitedPHIs;
/// InsertStackProtectors - Insert code into the prologue and epilogue of
/// the function.
///
/// - The prologue code loads and stores the stack guard onto the stack.
/// - The epilogue checks the value stored in the prologue against the
/// original value. It calls __stack_chk_fail if they differ.
bool InsertStackProtectors();
/// CreateFailBB - Create a basic block to jump to when the stack protector
/// check fails.
BasicBlock *CreateFailBB();
/// ContainsProtectableArray - Check whether the type either is an array or
/// contains an array of sufficient size so that we need stack protectors
/// for it.
bool ContainsProtectableArray(Type *Ty, bool Strong = false,
bool InStruct = false) const;
/// \brief Check whether a stack allocation has its address taken.
bool HasAddressTaken(const Instruction *AI);
/// RequiresStackProtector - Check whether or not this function needs a
/// stack protector based upon the stack protector level.
bool RequiresStackProtector();
public:
static char ID; // Pass identification, replacement for typeid.
StackProtector() : FunctionPass(ID), TM(0), TLI(0), SSPBufferSize(0) {
initializeStackProtectorPass(*PassRegistry::getPassRegistry());
}
StackProtector(const TargetMachine *TM)
: FunctionPass(ID), TM(TM), TLI(0), Trip(TM->getTargetTriple()),
SSPBufferSize(8) {
initializeStackProtectorPass(*PassRegistry::getPassRegistry());
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addPreserved<DominatorTree>();
}
virtual bool runOnFunction(Function &Fn);
};
} // end anonymous namespace
char StackProtector::ID = 0;
INITIALIZE_PASS(StackProtector, "stack-protector",
"Insert stack protectors", false, false)