[PATCH] D59780: Support Intel Control-flow Enforcement Technology

Tue Oct 15 01:58:59 PDT 2019

annita.zhang added a comment.

Hi,

I added a comment to x86-64 ABI google group link <https://groups.google.com/forum/?hl=en#!topic/x86-64-abi/sQcX3__r4c0>. I also posted it below.

This CET ABI issue was raised during glibc discussion in GCC Cauldron. The conclusion was CET ABI wouldn’t be changed. It’s not because it’s a better option, but because it’s been finalized for 2 years (in 2017). And the implementation has been included in Linux distributions already. There's no obvious reason to change it w/o a pretty better solution.

On the other hand, Intel wants to support it in LLVM lld anyway. But we don’t want to force lld developers to do what they don’t want. So now the ball is at lld side. If lld would like to follow the CET ABI, we’re willing to submit the corresponding lld patches. If not, we will submit the lld patches supporting 32-byte PLTs. The disadvantage of the latter is ABI is incompatible between GCC and LLVM for CET. It may cause potential issues in some tools which has dependence on PLT size and layout. But we don’t have known samples yet. From our estimation, the risk may be low.

I’m looking forward to hearing your opinions and moving it forward.

Thanks,
Annita

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https://reviews.llvm.org/D59780