Add Windows Control Flow Guard checks (/guard:cf).

Summary:
A new function pass (Transforms/CFGuard/CFGuard.cpp) inserts CFGuard checks on
indirect function calls, using either the check mechanism (X86, ARM, AArch64) or
or the dispatch mechanism (X86-64). The check mechanism requires a new calling
convention for the supported targets. The dispatch mechanism adds the target as
an operand bundle, which is processed by SelectionDAG. Another pass
(CodeGen/CFGuardLongjmp.cpp) identifies and emits valid longjmp targets, as
required by /guard:cf. This feature is enabled using the `cfguard` CC1 option.

Reviewers: thakis, rnk, theraven, pcc

Subscribers: ychen, hans, metalcanine, dmajor, tomrittervg, alex, mehdi_amini, mgorny, javed.absar, kristof.beyls, hiraditya, steven_wu, dexonsmith, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D65761

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86TargetMachine.cpp b/llvm/lib/Target/X86/X86TargetMachine.cpp
index c15297134e4..21f1ef9cb06 100644
--- a/llvm/lib/Target/X86/X86TargetMachine.cpp
+++ b/llvm/lib/Target/X86/X86TargetMachine.cpp
@@ -46,6 +46,7 @@
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Target/TargetLoweringObjectFile.h"
 #include "llvm/Target/TargetOptions.h"
+#include "llvm/Transforms/CFGuard.h"
 #include <memory>
 #include <string>
 
@@ -414,6 +415,16 @@ void X86PassConfig::addIRPasses() {
   // thunk. These will be a no-op unless a function subtarget has the retpoline
   // feature enabled.
   addPass(createIndirectBrExpandPass());
+
+  // Add Control Flow Guard checks.
+  const Triple &TT = TM->getTargetTriple();
+  if (TT.isOSWindows()) {
+    if (TT.getArch() == Triple::x86_64) {
+      addPass(createCFGuardDispatchPass());
+    } else {
+      addPass(createCFGuardCheckPass());
+    }
+  }
 }
 
 bool X86PassConfig::addInstSelector() {
@@ -530,6 +541,9 @@ void X86PassConfig::addPreEmitPass2() {
       (!TT.isOSWindows() ||
        MAI->getExceptionHandlingType() == ExceptionHandling::DwarfCFI))
     addPass(createCFIInstrInserter());
+  // Identify valid longjmp targets for Windows Control Flow Guard.
+  if (TT.isOSWindows())
+    addPass(createCFGuardLongjmpPass());
 }
 
 std::unique_ptr<CSEConfigBase> X86PassConfig::getCSEConfig() const {