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Enhance stack protector

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Reviewed By: LuoYuanke

Differential Revision: https://reviews.llvm.org/D139254
This commit is contained in:
Xiang1 Zhang
2022-12-09 19:16:00 +08:00
parent 26330e5f5d
commit d656ae2809
4 changed files with 152 additions and 138 deletions
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69
llvm/lib/CodeGen/StackProtector.cpp
View File

@@ -415,11 +415,11 @@ static Value *getStackGuard(const TargetLoweringBase *TLI, Module *M,
///
/// Returns true if the platform/triple supports the stackprotectorcreate pseudo
/// node.
static bool CreatePrologue(Function *F, Module *M, ReturnInst *RI,
static bool CreatePrologue(Function *F, Module *M, Instruction *CheckLoc,
const TargetLoweringBase *TLI, AllocaInst *&AI) {
bool SupportsSelectionDAGSP = false;
IRBuilder<> B(&F->getEntryBlock().front());
PointerType *PtrTy = Type::getInt8PtrTy(RI->getContext());
PointerType *PtrTy = Type::getInt8PtrTy(CheckLoc->getContext());
AI = B.CreateAlloca(PtrTy, nullptr, "StackGuardSlot");
Value *GuardSlot = getStackGuard(TLI, M, B, &SupportsSelectionDAGSP);
@@ -442,16 +442,34 @@ bool StackProtector::InsertStackProtectors() {
TLI->useStackGuardXorFP() ||
(EnableSelectionDAGSP && !TM->Options.EnableFastISel);
AllocaInst *AI = nullptr; // Place on stack that stores the stack guard.
bool RecalculateDT = false;
BasicBlock *FailBB = nullptr;
for (BasicBlock &BB : llvm::make_early_inc_range(*F)) {
ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator());
if (!RI)
// This is stack protector auto generated check BB, skip it.
if (&BB == FailBB)
continue;
Instruction *CheckLoc = dyn_cast<ReturnInst>(BB.getTerminator());
if (!CheckLoc) {
for (auto &Inst : BB) {
auto *CB = dyn_cast<CallBase>(&Inst);
if (!CB)
continue;
if (!CB->doesNotReturn())
continue;
// Do stack check before non-return calls (e.g: __cxa_throw)
CheckLoc = CB;
break;
}
}
if (!CheckLoc)
continue;
// Generate prologue instrumentation if not already generated.
if (!HasPrologue) {
HasPrologue = true;
SupportsSelectionDAGSP &= CreatePrologue(F, M, RI, TLI, AI);
SupportsSelectionDAGSP &= CreatePrologue(F, M, CheckLoc, TLI, AI);
}
// SelectionDAG based code generation. Nothing else needs to be done here.
@@ -477,8 +495,7 @@ bool StackProtector::InsertStackProtectors() {
// verifier guarantees that a tail call is either directly before the
// return or with a single correct bitcast of the return value in between so
// we don't need to worry about many situations here.
Instruction *CheckLoc = RI;
Instruction *Prev = RI->getPrevNonDebugInstruction();
Instruction *Prev = CheckLoc->getPrevNonDebugInstruction();
if (Prev && isa<CallInst>(Prev) && cast<CallInst>(Prev)->isTailCall())
CheckLoc = Prev;
else if (Prev) {
@@ -528,18 +545,13 @@ bool StackProtector::InsertStackProtectors() {
// Create the FailBB. We duplicate the BB every time since the MI tail
// merge pass will merge together all of the various BB into one including
// fail BB generated by the stack protector pseudo instruction.
BasicBlock *FailBB = CreateFailBB();
if (!FailBB)
FailBB = CreateFailBB();
// Split the basic block before the return instruction.
BasicBlock *NewBB =
BB.splitBasicBlock(CheckLoc->getIterator(), "SP_return");
// Update the dominator tree if we need to.
if (DT && DT->isReachableFromEntry(&BB)) {
DT->addNewBlock(NewBB, &BB);
DT->addNewBlock(FailBB, &BB);
}
// Remove default branch instruction to the new BB.
BB.getTerminator()->eraseFromParent();
@@ -560,9 +572,38 @@ bool StackProtector::InsertStackProtectors() {
.createBranchWeights(SuccessProb.getNumerator(),
FailureProb.getNumerator());
B.CreateCondBr(Cmp, NewBB, FailBB, Weights);
// Update the dominator tree if we need to.
if (DT && DT->isReachableFromEntry(&BB))
RecalculateDT = true;
}
}
// TODO: Refine me, use faster way to update DT.
// Now we have spilt the BB, some like:
// ===================================
// BB:
// RetOrNoReturnCall
// ==>
// BB:
// CondBr
// NewBB:
// RetOrNoReturnCall
// FailBB: (*)
// HandleStackCheckFail
// ===================================
// The faster way should cover:
// For NewBB, it should success the old BB's dominatees.
// 1) return: it didn't have dominatee
// 2) no-return call: there may has dominatees.
//
// For FailBB, it may be created before, So
// 1) if it has 1 Predecessors, add it into DT.
// 2) if it has 2 Predecessors, it should has no dominator, remove it from DT.
// 3) if it has 3 or more Predecessors, DT has removed it, do nothing.
if (RecalculateDT)
DT->recalculate(*F);
// Return if we didn't modify any basic blocks. i.e., there are no return
// statements in the function.
return HasPrologue;

30
llvm/test/CodeGen/X86/stack-protector-2.ll
View File

@@ -192,4 +192,34 @@ define dso_local void @bar_nossp(i64 %0) {
ret void
}
; Check stack protect for noreturn call
define dso_local i32 @foo_no_return(i32 %0) #1 {
; CHECK-LABEL: @foo_no_return
entry:
%cmp = icmp sgt i32 %0, 4
br i1 %cmp, label %if.then, label %if.end
; CHECK: if.then: ; preds = %entry
; CHECK-NEXT: %StackGuard1 = load volatile i8*, i8* addrspace(257)* inttoptr (i32 40 to i8* addrspace(257)*), align 8
; CHECK-NEXT: %1 = load volatile i8*, i8** %StackGuardSlot, align 8
; CHECK-NEXT: %2 = icmp eq i8* %StackGuard1, %1
; CHECK-NEXT: br i1 %2, label %SP_return, label %CallStackCheckFailBlk
; CHECK: SP_return: ; preds = %if.then
; CHECK-NEXT: %call = call i32 @foo_no_return(i32 1)
; CHECK-NEXT: br label %return
; CHECK: if.end: ; preds = %entry
; CHECK-NEXT: br label %return
if.then: ; preds = %entry
%call = call i32 @foo_no_return(i32 1)
br label %return
if.end: ; preds = %entry
br label %return
return: ; preds = %if.end, %if.then
ret i32 0
}
attributes #0 = { sspstrong }
attributes #1 = { noreturn sspreq}

165
llvm/test/CodeGen/X86/stack-protector-no-return.ll
View File

@@ -1,146 +1,63 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc %s -mtriple=x86_64-unknown-linux-gnu -o - -verify-dom-info | FileCheck %s
$__clang_call_terminate = comdat any
@_ZTIi = external dso_local constant i8*
@.str = private unnamed_addr constant [5 x i8] c"win\0A\00", align 1
; Function Attrs: mustprogress noreturn sspreq uwtable
define dso_local void @_Z7catchesv() local_unnamed_addr #0 personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
entry:
%exception = tail call i8* @__cxa_allocate_exception(i64 4) #8
%0 = bitcast i8* %exception to i32*
store i32 1, i32* %0, align 16
invoke void @__cxa_throw(i8* nonnull %exception, i8* bitcast (i8** @_ZTIi to i8*), i8* null) #9
to label %unreachable unwind label %lpad
lpad: ; preds = %entry
%1 = landingpad { i8*, i32 }
catch i8* null
%2 = extractvalue { i8*, i32 } %1, 0
%3 = tail call i8* @__cxa_begin_catch(i8* %2) #8
%call = invoke i64 @write(i32 noundef 1, i8* noundef getelementptr inbounds ([5 x i8], [5 x i8]* @.str, i64 0, i64 0), i64 noundef 4)
to label %invoke.cont unwind label %lpad1
invoke.cont: ; preds = %lpad
invoke void @_exit(i32 noundef 1) #9
to label %invoke.cont2 unwind label %lpad1
invoke.cont2: ; preds = %invoke.cont
unreachable
lpad1: ; preds = %invoke.cont, %lpad
%4 = landingpad { i8*, i32 }
cleanup
invoke void @__cxa_end_catch()
to label %eh.resume unwind label %terminate.lpad
eh.resume: ; preds = %lpad1
resume { i8*, i32 } %4
terminate.lpad: ; preds = %lpad1
%5 = landingpad { i8*, i32 }
catch i8* null
%6 = extractvalue { i8*, i32 } %5, 0
tail call void @__clang_call_terminate(i8* %6) #10
unreachable
unreachable: ; preds = %entry
unreachable
}
; Function Attrs: nofree
declare dso_local noalias i8* @__cxa_allocate_exception(i64) local_unnamed_addr #1
; Function Attrs: nofree noreturn
declare dso_local void @__cxa_throw(i8*, i8*, i8*) local_unnamed_addr #2
declare dso_local i32 @__gxx_personality_v0(...)
; Function Attrs: nofree
declare dso_local i8* @__cxa_begin_catch(i8*) local_unnamed_addr #1
; Function Attrs: nofree
declare dso_local noundef i64 @write(i32 noundef, i8* nocapture noundef readonly, i64 noundef) local_unnamed_addr #3
; Function Attrs: nofree noreturn
declare dso_local void @_exit(i32 noundef) local_unnamed_addr #4
; Function Attrs: nofree
declare dso_local void @__cxa_end_catch() local_unnamed_addr #1
; Function Attrs: noinline noreturn nounwind
define linkonce_odr hidden void @__clang_call_terminate(i8* %0) local_unnamed_addr #5 comdat {
; CHECK-LABEL: __clang_call_terminate:
; CHECK: # %bb.0:
; CHECK-NEXT: pushq %rax
; CHECK-NEXT: callq __cxa_begin_catch
; CHECK-NEXT: callq _ZSt9terminatev
%2 = tail call i8* @__cxa_begin_catch(i8* %0) #8
tail call void @_ZSt9terminatev() #10
unreachable
}
; Function Attrs: nofree noreturn nounwind
declare dso_local void @_ZSt9terminatev() local_unnamed_addr #6
; Function Attrs: mustprogress nofree sspreq uwtable
define dso_local void @_Z4vulni(i32 noundef %op) local_unnamed_addr #7 {
; CHECK-LABEL: _Z4vulni:
; Function Attrs: sspreq
define void @_Z7catchesv() #0 personality i8* null {
; CHECK-LABEL: _Z7catchesv:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: pushq %rax
; CHECK-NEXT: .cfi_def_cfa_offset 16
; CHECK-NEXT: movq %fs:40, %rax
; CHECK-NEXT: movq %rax, (%rsp)
; CHECK-NEXT: cmpl $1, %edi
; CHECK-NEXT: je .LBB2_3
; CHECK-NEXT: # %bb.1: # %if.end
; CHECK-NEXT: .Ltmp0:
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: xorl %edi, %edi
; CHECK-NEXT: xorl %esi, %esi
; CHECK-NEXT: xorl %edx, %edx
; CHECK-NEXT: callq *%rax
; CHECK-NEXT: .Ltmp1:
; CHECK-NEXT: # %bb.1: # %invoke.cont
; CHECK-NEXT: movq %fs:40, %rax
; CHECK-NEXT: cmpq (%rsp), %rax
; CHECK-NEXT: jne .LBB2_2
; CHECK-NEXT: # %bb.4: # %SP_return
; CHECK-NEXT: jne .LBB0_6
; CHECK-NEXT: # %bb.2: # %SP_return
; CHECK-NEXT: .Ltmp2:
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: xorl %edi, %edi
; CHECK-NEXT: callq *%rax
; CHECK-NEXT: .Ltmp3:
; CHECK-NEXT: # %bb.3: # %invoke.cont2
; CHECK-NEXT: .LBB0_4: # %lpad1
; CHECK-NEXT: .Ltmp4:
; CHECK-NEXT: movq %fs:40, %rax
; CHECK-NEXT: cmpq (%rsp), %rax
; CHECK-NEXT: jne .LBB0_6
; CHECK-NEXT: # %bb.5: # %SP_return2
; CHECK-NEXT: popq %rax
; CHECK-NEXT: .cfi_def_cfa_offset 8
; CHECK-NEXT: retq
; CHECK-NEXT: .LBB2_3: # %if.then
; CHECK-NEXT: .LBB0_6: # %CallStackCheckFailBlk
; CHECK-NEXT: .cfi_def_cfa_offset 16
; CHECK-NEXT: movl $4, %edi
; CHECK-NEXT: callq __cxa_allocate_exception
; CHECK-NEXT: movl $1, (%rax)
; CHECK-NEXT: movl $_ZTIi, %esi
; CHECK-NEXT: movq %rax, %rdi
; CHECK-NEXT: xorl %edx, %edx
; CHECK-NEXT: callq __cxa_throw
; CHECK-NEXT: .LBB2_2: # %CallStackCheckFailBlk
; CHECK-NEXT: callq __stack_chk_fail@PLT
entry:
%cmp = icmp eq i32 %op, 1
br i1 %cmp, label %if.then, label %if.end
%call = invoke i64 null(i32 0, i8* null, i64 0)
to label %invoke.cont unwind label %lpad1
if.then: ; preds = %entry
%exception = tail call i8* @__cxa_allocate_exception(i64 4) #8
%0 = bitcast i8* %exception to i32*
store i32 1, i32* %0, align 16
tail call void @__cxa_throw(i8* %exception, i8* bitcast (i8** @_ZTIi to i8*), i8* null) #9
invoke.cont: ; preds = %entry
invoke void null(i32 0) #1
to label %invoke.cont2 unwind label %lpad1
invoke.cont2: ; preds = %invoke.cont
unreachable
if.end: ; preds = %entry
lpad1: ; preds = %invoke.cont, %entry
%0 = landingpad { i8*, i32 }
cleanup
ret void
}
attributes #0 = { mustprogress noreturn sspreq uwtable }
attributes #1 = { nofree }
attributes #2 = { nofree noreturn }
attributes #3 = { nofree }
attributes #4 = { nofree noreturn }
attributes #5 = { noinline noreturn nounwind }
attributes #6 = { nofree noreturn nounwind }
attributes #7 = { mustprogress nofree sspreq uwtable }
attributes #8 = { nounwind }
attributes #9 = { noreturn }
attributes #10 = { noreturn nounwind }
; uselistorder directives
uselistorder i8* null, { 1, 0 }
attributes #0 = { sspreq }
attributes #1 = { noreturn }

26
llvm/test/CodeGen/X86/stack-protector-recursively.ll Normal file
View File

@@ -0,0 +1,26 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %s | FileCheck %s
; Make sure the stack protect not infinitly check __stack_chk_fail.
define dso_local void @__stack_chk_fail() local_unnamed_addr #0 {
; CHECK-LABEL: __stack_chk_fail:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: pushq %rax
; CHECK-NEXT: movq %fs:40, %rax
; CHECK-NEXT: movq %rax, (%rsp)
; CHECK-NEXT: movq %fs:40, %rax
; CHECK-NEXT: cmpq (%rsp), %rax
; CHECK-NEXT: jne .LBB0_2
; CHECK-NEXT: # %bb.1: # %SP_return
; CHECK-NEXT: ud2
; CHECK-NEXT: .LBB0_2: # %CallStackCheckFailBlk
; CHECK-NEXT: callq __stack_chk_fail
entry:
tail call void @llvm.trap()
unreachable
}
declare void @llvm.trap() #1
attributes #0 = { noreturn nounwind sspreq }
attributes #1 = { noreturn nounwind }