linux-kernel - Re: [PATCH v7 1/4] x86/insn-eval: Add support for 64-bit kernel mode

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Date:   Thu, 2 Jan 2020 10:47:05 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Jann Horn <jannh@...gle.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH v7 1/4] x86/insn-eval: Add support for 64-bit kernel mode

On Thu, Dec 19, 2019 at 12:11:47AM +0100, Jann Horn wrote:
> To support evaluating 64-bit kernel mode instructions:
> 
> Replace existing checks for user_64bit_mode() with a new helper that
> checks whether code is being executed in either 64-bit kernel mode or
> 64-bit user mode.
> 
> Select the GS base depending on whether the instruction is being
> evaluated in kernel mode.
> 
> Signed-off-by: Jann Horn <jannh@...gle.com>

In most cases you have struct insn around (or can easily pass it down to
the place). Why not use insn->x86_64?

-- 
 Kirill A. Shutemov