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Date:   Wed, 20 Apr 2022 15:50:13 -0700
From:   Joao Moreira <joao@overdrivepizza.com>
To:     Kees Cook <keescook@chromium.org>
Cc:     linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org,
        peterz@infradead.org, jpoimboe@redhat.com,
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        alyssa.milburn@linux.intel.com, ndesaulniers@google.com,
        gabriel.gomes@linux.intel.com, rick.p.edgecombe@intel.com
Subject: Re: [RFC PATCH 00/11] Kernel FineIBT Support
In-Reply-To: <202204191937.2720E7E@keescook>
References: <20220420004241.2093-1-joao@overdrivepizza.com>
 <202204191937.2720E7E@keescook>
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> I think it'd be good to get kCFI landed in Clang first (since it is
> effectively architecture agnostic), and then get FineIBT landed. But
> that doesn't mean we can't be working on the kernel side of things at
> the same time.

FWIIW, I'm effectively taking some time away from work for the next 3 
months. I'll be around to answer this and that, help reviewing KCFI and 
maybe send small fixes around, but I'm not planning to land FineIBT in 
clang anytime before that (specially now that I have a direction to look 
into the linker approach as per the other thread e-mails). This should 
give KCFI the time it needs to squeeze in.

> 
> And just thinking generally, for other architecture-specific stuff,
> I do wonder what an arm64 PAC-based CFI might look like. I prefer 
> things
> be hard-coded as kCFI is doing, but it'd be nice to be able to directly
> measure performance and size overheads comparing the various methods.

There are other important bullets to this list, I think, like power 
consumption, robustness and collateral gains (like IBT's side-channel 
hardening). But yeah, this is probably a good list to keep in mind for 
us to discuss during plumbers :)