[clang] [llvm] [ARM][KCFI] Add backend support for Kernel Control-Flow Integrity (PR #163698)

[Sami Tolvanen via cfe-commits]

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@@ -12007,6 +12011,49 @@ static void genTPLoopBody(MachineBasicBlock *TpLoopBody,
       .add(predOps(ARMCC::AL));
 }
 
+bool ARMTargetLowering::supportKCFIBundles() const {
+  // KCFI is only supported in ARM mode, not Thumb mode
+  return !Subtarget->isThumb();
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samitolvanen wrote:

I believe it would require KCFI_CHECK lowering for Thumb, and you'll need make sure you clear the LSB from the function address when calculating the hash location, because ARM uses that to select between ARM/Thumb mode for the callee.

https://github.com/llvm/llvm-project/pull/163698