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

2020-06-18 Thread Thomas Gleixner 
Andy Lutomirski  writes:
> 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?

Not that I'm aware of.

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

2020-06-18 Thread Andy Lutomirski 
On Thu, Jun 18, 2020 at 7:18 AM Thomas Gleixner  wrote:
>
> Sasha,
>
> Sasha Levin  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?

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

2020-06-18 Thread Thomas Gleixner 
Sasha,

Sasha Levin  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!

   tglx