linux-kernel - Re: [PATCH v2 04/39] x86/cpufeatures: Enable CET CR4 bit for shadow stack

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Message-ID: <Y0m8IoU/I3y8JMQh@zn.tnic>
Date:   Fri, 14 Oct 2022 21:44:34 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
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Subject: Re: [PATCH v2 04/39] x86/cpufeatures: Enable CET CR4 bit for shadow
 stack

On Fri, Oct 14, 2022 at 06:15:30PM +0000, Edgecombe, Rick P wrote:
> Andrew Cooper has suggested to create some software cpu features to
> differentiate user/supervisor CET feature use. It could replace
> HAS_KERNEL_IBT. Any objections to that versus Kconfig symbols?

Sure, except you can't use them in

arch/x86/include/asm/idtentry.h:8:#define IDT_ALIGN     (8 * (1 + HAS_KERNEL_IBT))

as that gets used in asm code.

But you don't have to do this in this patchset - it is huge already
anyway. I have this thing on my todo so I'll get to it eventually.
Unless you're itching to remove it yourself - then I won't stay in the
way.

:-)

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette