[PATCH] D88194: [X86] CET endbr enhance

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

In D88194#2321872 <https://reviews.llvm.org/D88194#2321872>, @spatel wrote:

> In D88194#2318848 <https://reviews.llvm.org/D88194#2318848>, @xiangzhangllvm wrote:
>
>> CET adds an Indirect Branch Tracking capability (by inserting Endbr instruction at the destination of the indirect branch) to provide software the ability to restrict COP/JOP attacks.
>
> Ok, I understand that much. But it is still not clear to me why this patch is re-using the "-x86-indirect-branch-tracking" option. Is this obscuring of the opcode not independent of producing the instruction? I would again suggest that we pre-commit some tests, so we can see only the diffs in the codegen (and if inserting "endb64" itself is a requirement to obscure the opcode, please add comments in the test file to explain that).

I suggested adding that the -x86-indirect-branch-tracking check because it seemed like we'd only want to do this in a binary that was expected to contain endbr opcodes. Putting things that could be confused for endbr opcodes in a binary that doesn't enable CET should be harmless.


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