linux-kernel - Re: [PATCH] arch: x86: power: cpu: init %gs before __restore_processor

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Message-ID: <20200915182730.GW14436@zn.tnic>
Date:   Tue, 15 Sep 2020 20:27:30 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Roman Kiryanov <rkir@...gle.com>
Cc:     rjw@...ysocki.net, pavel@....cz,
        Thomas Gleixner <tglx@...utronix.de>, mingo@...hat.com,
        x86@...nel.org, linux-pm@...r.kernel.org,
        Greg KH <gregkh@...uxfoundation.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Alistair Delva <adelva@...gle.com>,
        Haitao Shan <hshan@...gle.com>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arch: x86: power: cpu: init %gs before
 __restore_processor_state (clang)

On Tue, Sep 15, 2020 at 10:57:16AM -0700, Roman Kiryanov wrote:
> I believe the kernel makes a questionable assumption on how clang
> uses registers (gs will not be used if stack protection is disabled).
> Both kernel and clang behaves unfortunate here.

If the kernel is at fault here and this same thing happens with GCC,
sure, but this is a clang-specific fix.

-- 
Regards/Gruss,
    Boris.

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