Re: [PATCH v13 00/16] Enable FSGSBASE instructions

[Andy Lutomirski]

On Thu, Jun 18, 2020 at 7:18 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>
> Sasha,
>
> Sasha Levin <sashal@xxxxxxxxxx> writes:
> > Changes from v12:
> >  - Reformat the series to be closer to the reverted codebase for easier
> >    review.
> >  - Drop a few of the changes introduced in v8 and v9.
>
> I've pushed the lot out to
>
>    git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/fsgsbase
>
> Thanks for taking this up!
>

Is there a plan to deal with:

        /*
         * This function has some ABI oddities.
         *
         * A 32-bit ptracer probably expects that writing FS or GS will change
         * FSBASE or GSBASE respectively.  In the absence of FSGSBASE support,
         * this code indeed has that effect.  When FSGSBASE is added, this
         * will require a special case.
         *
         * For existing 64-bit ptracers, writing FS or GS *also* currently
         * changes the base if the selector is nonzero the next time the task
         * is run.  This behavior may? not be needed, and trying to preserve it
         * when FSGSBASE is added would be complicated at best.
         */

in arch/x86/kernel/ptrace.c?