linux-kernel - Re: [PATCH 03/35] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET)

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Message-ID: <f1fe9c992131dfa989c6d321097642cce5f4830a.camel@intel.com>
Date:   Tue, 8 Feb 2022 20:23:24 +0000
From:   "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
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CC:     "Yu, Yu-cheng" <yu-cheng.yu@...el.com>
Subject: Re: [PATCH 03/35] x86/cpufeatures: Add CET CPU feature flags for
 Control-flow Enforcement Technology (CET)

On Mon, 2022-02-07 at 14:45 -0800, Dave Hansen wrote:
> Please add a chunk to the changelog that explains the dependency. 
> This
> would suffice:
> 
>         To protect shadow stack state from malicious modification,
> the
>         registers are only accessible in supervisor mode.  This
>         implementation context-switches the registers with XSAVES. 
> Make
>         X86_FEATURE_SHSTK depend on XSAVES.

Thanks. Yea, I don't think that part of the design is really elaborated
on anywhere. It can be some foreshadowing for the signal stuff later
too.