[llvm] r361342 - [X86] [CET] Deal with return-twice function such as vfork, setjmp when
Pengfei Wang via llvm-commits
llvm-commits at lists.llvm.org
Tue May 21 17:50:21 PDT 2019
Author: pengfei
Date: Tue May 21 17:50:21 2019
New Revision: 361342
URL: http://llvm.org/viewvc/llvm-project?rev=361342&view=rev
Log:
[X86] [CET] Deal with return-twice function such as vfork, setjmp when
CET-IBT enabled
Return-twice functions will indirectly jump after the caller's position.
So when CET-IBT is enable, we should make sure these is endbr*
instructions follow these Return-twice function caller. Like GCC does.
Patch by Xiang Zhang (xiangzhangllvm)
Differential Revision: https://reviews.llvm.org/D61881
Added:
llvm/trunk/test/CodeGen/X86/indirect-branch-tracking-r2.ll
Modified:
llvm/trunk/lib/Target/X86/X86IndirectBranchTracking.cpp
Modified: llvm/trunk/lib/Target/X86/X86IndirectBranchTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86IndirectBranchTracking.cpp?rev=361342&r1=361341&r2=361342&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86IndirectBranchTracking.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86IndirectBranchTracking.cpp Tue May 21 17:50:21 2019
@@ -57,7 +57,7 @@ private:
/// The function will not add it if already exists.
/// It will add ENDBR32 or ENDBR64 opcode, depending on the target.
/// \returns true if the ENDBR was added and false otherwise.
- bool addENDBR(MachineBasicBlock &MBB) const;
+ bool addENDBR(MachineBasicBlock &MBB, MachineBasicBlock::iterator I) const;
};
} // end anonymous namespace
@@ -68,20 +68,31 @@ FunctionPass *llvm::createX86IndirectBra
return new X86IndirectBranchTrackingPass();
}
-bool X86IndirectBranchTrackingPass::addENDBR(MachineBasicBlock &MBB) const {
+bool X86IndirectBranchTrackingPass::addENDBR(
+ MachineBasicBlock &MBB, MachineBasicBlock::iterator I) const {
assert(TII && "Target instruction info was not initialized");
assert((X86::ENDBR64 == EndbrOpcode || X86::ENDBR32 == EndbrOpcode) &&
"Unexpected Endbr opcode");
- auto MI = MBB.begin();
- // If the MBB is empty or the first instruction is not ENDBR,
- // add the ENDBR instruction to the beginning of the MBB.
- if (MI == MBB.end() || EndbrOpcode != MI->getOpcode()) {
- BuildMI(MBB, MI, MBB.findDebugLoc(MI), TII->get(EndbrOpcode));
- NumEndBranchAdded++;
+ // If the MBB/I is empty or the current instruction is not ENDBR,
+ // insert ENDBR instruction to the location of I.
+ if (I == MBB.end() || I->getOpcode() != EndbrOpcode) {
+ BuildMI(MBB, I, MBB.findDebugLoc(I), TII->get(EndbrOpcode));
+ ++NumEndBranchAdded;
return true;
}
+ return false;
+}
+bool IsCallReturnTwice(llvm::MachineOperand &MOp) {
+ if (!MOp.isGlobal())
+ return false;
+ auto *CalleeFn = dyn_cast<Function>(MOp.getGlobal());
+ if (!CalleeFn)
+ return false;
+ AttributeList Attrs = CalleeFn->getAttributes();
+ if (Attrs.hasAttribute(AttributeList::FunctionIndex, Attribute::ReturnsTwice))
+ return true;
return false;
}
@@ -107,14 +118,21 @@ bool X86IndirectBranchTrackingPass::runO
!MF.getFunction().hasLocalLinkage()) &&
!MF.getFunction().doesNoCfCheck()) {
auto MBB = MF.begin();
- Changed |= addENDBR(*MBB);
+ Changed |= addENDBR(*MBB, MBB->begin());
}
- for (auto &MBB : MF)
+ for (auto &MBB : MF) {
// Find all basic blocks that their address was taken (for example
// in the case of indirect jump) and add ENDBR instruction.
if (MBB.hasAddressTaken())
- Changed |= addENDBR(MBB);
+ Changed |= addENDBR(MBB, MBB.begin());
+ for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I) {
+ if (!I->isCall())
+ continue;
+ if (IsCallReturnTwice(I->getOperand(0)))
+ Changed |= addENDBR(MBB, std::next(I));
+ }
+ }
return Changed;
}
Added: llvm/trunk/test/CodeGen/X86/indirect-branch-tracking-r2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/indirect-branch-tracking-r2.ll?rev=361342&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/indirect-branch-tracking-r2.ll (added)
+++ llvm/trunk/test/CodeGen/X86/indirect-branch-tracking-r2.ll Tue May 21 17:50:21 2019
@@ -0,0 +1,76 @@
+; RUN: llc -mtriple=x86_64-unknown-unknown < %s | FileCheck %s --check-prefix=X64
+; RUN: llc -mtriple=i386-unknown-unknown < %s | FileCheck %s --check-prefix=X86
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; foo
+;; -----
+;; Checks ENDBR insertion after return twice functions.
+;; setjmp, sigsetjmp, savectx, vfork, getcontext
+;; setzx is not return twice function, should not followed by endbr.
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+; X64: callq setjmp
+; X64-NEXT: endbr64
+; X64: callq setzx
+; X64-NEXT: xorl
+; X64: callq sigsetjmp
+; X64-NEXT: endbr64
+; X64: callq savectx
+; X64-NEXT: endbr64
+; X64: callq vfork
+; X64-NEXT: endbr64
+; X64: callq getcontext
+; X64-NEXT: endbr64
+
+; X86: calll setjmp
+; X86-NEXT: endbr32
+; X86: calll setzx
+; X86-NEXT: xorl
+; X86: calll sigsetjmp
+; X86-NEXT: endbr32
+; X86: calll savectx
+; X86-NEXT: endbr32
+; X86: calll vfork
+; X86-NEXT: endbr32
+; X86: calll getcontext
+; X86-NEXT: endbr32
+
+; Function Attrs: noinline nounwind optnone uwtable
+define dso_local void @foo() #0 {
+entry:
+ %call = call i32 (i32, ...) bitcast (i32 (...)* @setjmp to i32 (i32, ...)*)(i32 0) #1
+ %call1 = call i32 (i32, ...) bitcast (i32 (...)* @setzx to i32 (i32, ...)*)(i32 0)
+ %call2 = call i32 (i32, ...) bitcast (i32 (...)* @sigsetjmp to i32 (i32, ...)*)(i32 0) #1
+ %call3 = call i32 (i32, ...) bitcast (i32 (...)* @setzx to i32 (i32, ...)*)(i32 0)
+ %call4 = call i32 (i32, ...) bitcast (i32 (...)* @savectx to i32 (i32, ...)*)(i32 0) #1
+ %call5 = call i32 @vfork() #1
+ %call6 = call i32 (i32, ...) bitcast (i32 (...)* @setzx to i32 (i32, ...)*)(i32 0)
+ %call7 = call i32 (i32, ...) bitcast (i32 (...)* @getcontext to i32 (i32, ...)*)(i32 0) #1
+ ret void
+}
+
+; Function Attrs: returns_twice
+declare dso_local i32 @setjmp(...) #1
+
+declare dso_local i32 @setzx(...)
+
+; Function Attrs: returns_twice
+declare dso_local i32 @sigsetjmp(...) #1
+
+; Function Attrs: returns_twice
+declare dso_local i32 @savectx(...) #1
+
+; Function Attrs: returns_twice
+declare dso_local i32 @vfork() #1
+
+; Function Attrs: returns_twice
+declare dso_local i32 @getcontext(...) #1
+
+attributes #0 = { noinline nounwind optnone uwtable }
+attributes #1 = { returns_twice }
+
+!llvm.module.flags = !{!0, !1, !2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 4, !"cf-protection-return", i32 1}
+!2 = !{i32 4, !"cf-protection-branch", i32 1}
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