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CET for Exception Handle 

Summary:
Bug fix for https://bugs.llvm.org/show_bug.cgi?id=45182
Exception handle may indirectly jump to catch pad, So we should add ENDBR instruction before catch pad instructions.

Reviewers: craig.topper, hjl.tools, LuoYuanke, annita.zhang, pengfei

Reviewed By: LuoYuanke

Subscribers: hiraditya, llvm-commits

Patch By: Xiang Zhang (xiangzhangllvm)

Differential Revision: https://reviews.llvm.org/D76190
This commit is contained in:
Pengfei Wang 2020-03-17 21:39:49 -07:00
parent 4d35055635
commit 974d649f8e
2 changed files with 41 additions and 3 deletions
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13
llvm/lib/Target/X86/X86IndirectBranchTracking.cpp
View File

@ -127,11 +127,18 @@ bool X86IndirectBranchTrackingPass::runOnMachineFunction(MachineFunction &MF) {
if (MBB.hasAddressTaken())
Changed |= addENDBR(MBB, MBB.begin());
// Exception handle may indirectly jump to catch pad, So we should add
// ENDBR before catch pad instructions.
bool EHPadIBTNeeded = MBB.isEHPad();
for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I) {
if (!I->isCall())
continue;
if (IsCallReturnTwice(I->getOperand(0)))
if (I->isCall() && IsCallReturnTwice(I->getOperand(0)))
Changed |= addENDBR(MBB, std::next(I));
if (EHPadIBTNeeded && I->isEHLabel()) {
Changed |= addENDBR(MBB, std::next(I));
EHPadIBTNeeded = false;
}
}
}
return Changed;

31
llvm/test/CodeGen/X86/indirect-branch-tracking-eh.ll Normal file
View File

@ -0,0 +1,31 @@
; RUN: llc -mtriple=x86_64-unknown-unknown < %s | FileCheck %s
; RUN: llc -mtriple=i386-unknown-unknown < %s | FileCheck %s
;There should be 2 endbr* instruction at entry and catch pad.
;CHECK-COUNT-2: endbr
declare void @_Z20function_that_throwsv()
declare i32 @__gxx_personality_sj0(...)
declare i8* @__cxa_begin_catch(i8*)
declare void @__cxa_end_catch()
define void @test8() personality i8* bitcast (i32 (...)* @__gxx_personality_sj0 to i8*) {
entry:
invoke void @_Z20function_that_throwsv()
to label %try.cont unwind label %lpad
lpad:
%0 = landingpad { i8*, i32 }
catch i8* null
%1 = extractvalue { i8*, i32 } %0, 0
%2 = tail call i8* @__cxa_begin_catch(i8* %1)
tail call void @__cxa_end_catch()
br label %try.cont
try.cont:
ret void
}
!llvm.module.flags = !{!0}
!0 = !{i32 4, !"cf-protection-branch", i32 1}