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

[Kees Cook via cfe-commits]

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@@ -687,7 +687,9 @@ static void addKCFIPass(const Triple &TargetTriple, const LangOptions &LangOpts,
                         PassBuilder &PB) {
   // If the back-end supports KCFI operand bundle lowering, skip KCFIPass.
   if (TargetTriple.getArch() == llvm::Triple::x86_64 ||
-      TargetTriple.isAArch64(64) || TargetTriple.isRISCV())
+      TargetTriple.isAArch64(64) || TargetTriple.isRISCV() ||
+      TargetTriple.getArch() == llvm::Triple::arm ||
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kees wrote:

I've implemented Thumb2 and Thumb1 now. As far as the XOR thing, it would still require reading back the instructions to discover the typeid offset, and then also reading from "target address - offset" to get the value. But that's all Linux-side anyway.

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