StackProtector.cpp File Reference

#include "llvm/CodeGen/StackProtector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/EHPersonalities.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/User.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include <optional>
#include <utility>

Go to the source code of this file.

Classes
struct	PhiInfo
	Maximum remaining allocation size observed for a phi node, and how often the allocation size has already been decreased. More...

Macros
#define	DEBUG_TYPE   "stack-protector"

Typedefs
using	PhiMap = SmallDenseMap< const PHINode *, PhiInfo, 16 >

Functions
	STATISTIC (NumFunProtected, "Number of functions protected")
	STATISTIC (NumAddrTaken, "Number of local variables that have their address" " taken.")
static bool	InsertStackProtectors (const TargetMachine *TM, Function *F, DomTreeUpdater *DTU, bool &HasPrologue, bool &HasIRCheck)
	InsertStackProtectors - Insert code into the prologue and epilogue of the function.
static BasicBlock *	CreateFailBB (Function *F, const TargetLowering &TLI)
	CreateFailBB - Create a basic block to jump to when the stack protector check fails.
	INITIALIZE_PASS_BEGIN (StackProtector, DEBUG_TYPE, "Insert stack protectors", false, true) INITIALIZE_PASS_END(StackProtector
static bool	ContainsProtectableArray (Type *Ty, Module *M, unsigned SSPBufferSize, bool &IsLarge, bool Strong, bool InStruct)
static bool	HasAddressTaken (const Instruction *AI, TypeSize AllocSize, Module *M, PhiMap &VisitedPHIs)
	Check whether a stack allocation has its address taken.
static const CallInst *	findStackProtectorIntrinsic (Function &F)
	Search for the first call to the llvm.stackprotector intrinsic and return it if present.
static Value *	getStackGuard (const TargetLoweringBase *TLI, Module *M, IRBuilder<> &B, bool *SupportsSelectionDAGSP=nullptr)
	Create a stack guard loading and populate whether SelectionDAG SSP is supported.
static bool	CreatePrologue (Function *F, Module *M, Instruction *CheckLoc, const TargetLoweringBase *TLI, AllocaInst *&AI)
	Insert code into the entry block that stores the stack guard variable onto the stack:

Variables
static cl::opt< bool >	EnableSelectionDAGSP ("enable-selectiondag-sp", cl::init(true), cl::Hidden)
static cl::opt< bool >	DisableCheckNoReturn ("disable-check-noreturn-call", cl::init(false), cl::Hidden)
	DEBUG_TYPE
Insert stack	protectors
Insert stack	false

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "stack-protector"

Definition at line 56 of file StackProtector.cpp.

Typedef Documentation

PhiMap

using PhiMap = SmallDenseMap<const PHINode *, PhiInfo, 16>

Definition at line 264 of file StackProtector.cpp.

Function Documentation

ContainsProtectableArray()

static bool ContainsProtectableArray ( Type *  Ty, Module *  M, unsigned  SSPBufferSize, bool &  IsLarge, bool  Strong, bool  InStruct  )

static

Parameters

[out]

IsLarge

is set to true if a protectable array is found and it is "large" ( >= ssp-buffer-size). In the case of a structure with multiple arrays, this gets set if any of them is large.

Definition at line 210 of file StackProtector.cpp.

References ContainsProtectableArray().

Referenced by ContainsProtectableArray(), and llvm::SSPLayoutAnalysis::requiresStackProtector().

CreateFailBB()

BasicBlock * CreateFailBB ( Function *  F, const TargetLowering &  TLI  )

static

CreateFailBB - Create a basic block to jump to when the stack protector check fails.

Definition at line 717 of file StackProtector.cpp.

References B, Context, llvm::BasicBlock::Create(), F, llvm::MDNode::get(), llvm::TargetLoweringBase::getLibcallName(), llvm::PointerType::getUnqual(), and llvm::Type::getVoidTy().

Referenced by InsertStackProtectors().

CreatePrologue()

static bool CreatePrologue ( Function *  F, Module *  M, Instruction *  CheckLoc, const TargetLoweringBase *  TLI, AllocaInst *&  AI  )

static

Insert code into the entry block that stores the stack guard variable onto the stack:

entry: StackGuardSlot = alloca i8* StackGuard = <stack guard> call void @llvm.stackprotector(StackGuard, StackGuardSlot)

Returns true if the platform/triple supports the stackprotectorcreate pseudo node.

Definition at line 558 of file StackProtector.cpp.

References B, F, llvm::Value::getContext(), getStackGuard(), and llvm::PointerType::getUnqual().

Referenced by InsertStackProtectors().

findStackProtectorIntrinsic()

static const CallInst * findStackProtectorIntrinsic ( Function &  F )

static

Search for the first call to the llvm.stackprotector intrinsic and return it if present.

Definition at line 372 of file StackProtector.cpp.

References F, I, and II.

Referenced by InsertStackProtectors().

getStackGuard()

static Value * getStackGuard ( const TargetLoweringBase *  TLI, Module *  M, IRBuilder<> &  B, bool *  SupportsSelectionDAGSP = nullptr  )

static

Create a stack guard loading and populate whether SelectionDAG SSP is supported.

Definition at line 523 of file StackProtector.cpp.

References B, llvm::StringRef::empty(), llvm::TargetLoweringBase::getIRStackGuard(), and llvm::TargetLoweringBase::insertSSPDeclarations().

Referenced by CreatePrologue(), and InsertStackProtectors().

HasAddressTaken()

static bool HasAddressTaken ( const Instruction *  AI, TypeSize  AllocSize, Module *  M, PhiMap &  VisitedPHIs  )

static

Check whether a stack allocation has its address taken.

Definition at line 267 of file StackProtector.cpp.

References DL, GEP, llvm::TypeSize::getFixed(), llvm::details::FixedOrScalableQuantity< LeafTy, ValueTy >::getKnownMinValue(), llvm::MemoryLocation::getOrNone(), HasAddressTaken(), I, llvm::details::FixedOrScalableQuantity< TypeSize, uint64_t >::isKnownGE(), llvm::details::FixedOrScalableQuantity< TypeSize, uint64_t >::isKnownGT(), PhiInfo::MaxNumDecreased, llvm::Offset, llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::try_emplace(), and llvm::Value::users().

Referenced by HasAddressTaken(), and llvm::SSPLayoutAnalysis::requiresStackProtector().

INITIALIZE_PASS_BEGIN()

INITIALIZE_PASS_BEGIN	(	StackProtector	,
		DEBUG_TYPE	,
		"Insert stack protectors"	,
		false	,
		true
	)

InsertStackProtectors()

bool InsertStackProtectors ( const TargetMachine *  TM, Function *  F, DomTreeUpdater *  DTU, bool &  HasPrologue, bool &  HasIRCheck  )

static

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.

Definition at line 570 of file StackProtector.cpp.

References assert(), B, llvm::MDBuilder::createBranchWeights(), CreateFailBB(), CreatePrologue(), DisableCheckNoReturn, EnableSelectionDAGSP, F, findStackProtectorIntrinsic(), llvm::CallBase::getArgOperand(), llvm::BranchProbabilityInfo::getBranchProbStackProtector(), llvm::ilist_node_with_parent< NodeTy, ParentTy, Options >::getPrevNode(), getStackGuard(), llvm::isInTailCallPosition(), llvm::make_early_inc_range(), llvm::BasicBlock::moveAfter(), llvm::Value::setName(), and llvm::SplitBlockAndInsertIfThen().

Referenced by llvm::StackProtectorPass::run(), and llvm::StackProtector::runOnFunction().

STATISTIC() [1/2]

STATISTIC	(	NumAddrTaken	,
		"Number of local variables that have their address" " taken."
	)

STATISTIC() [2/2]

STATISTIC	(	NumFunProtected	,
		"Number of functions protected"
	)

Variable Documentation

DEBUG_TYPE

DEBUG_TYPE

Definition at line 162 of file StackProtector.cpp.

DisableCheckNoReturn

cl::opt< bool > DisableCheckNoReturn("disable-check-noreturn-call", cl::init(false), cl::Hidden) ( "disable-check-noreturn-call"  , cl::init(false)  , cl::Hidden    )

static

Referenced by InsertStackProtectors().

EnableSelectionDAGSP

cl::opt< bool > EnableSelectionDAGSP("enable-selectiondag-sp", cl::init(true), cl::Hidden) ( "enable-selectiondag-sp"  , cl::init(true)  , cl::Hidden    )

static

Referenced by InsertStackProtectors().

false

Insert stack false

Definition at line 163 of file StackProtector.cpp.

protectors

Insert stack protectors

Definition at line 163 of file StackProtector.cpp.