Re: [Xen-devel] Patch "x86/entry/64: Remove %ebx handling from error_entry/exit" has been added to the 4.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

On Wed, Nov 28, 2018 at 02:56:32PM +0000, David Woodhouse wrote:
> On Wed, 2018-08-22 at 09:19 +0200, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
> > This is a note to let you know that I've just added the patch titled
> >
> >     x86/entry/64: Remove %ebx handling from error_entry/exit
> >
> > to the 4.9-stable tree which can be found at:
> >     
> > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> >
> > The filename of the patch is:
> >      x86-entry-64-remove-ebx-handling-from-error_entry-exit.patch
> > and it can be found in the queue-4.9 subdirectory.
> Can we have it for 4.4 too, please?
>
> > [ Note to stable maintainers: this should probably get applied to all
> >   kernels.  If you're nervous about that, a more conservative fix to
> >   add xorl %ebx,%ebx; incl %ebx before the jump to error_exit should
> >   also fix the problem. ]
> Can we assume it's always from kernel? The Xen code definitely seems to
> handle invoking this from both kernel and userspace contexts.
>
> Shouldn't %ebx get set to !(regs->rsp & 3) ?
>
> Either way, let's just do it in the stable tree exactly the same way
> it's done upstream.
>
> > - * On entry, EBX is a "return to kernel mode" flag:
> Re-introduce the typo 'EBS' here, to make the patch apply cleanly to
> 4.4. It's only removing that line anyway.
>
> Or just cherry-pick upstream commit 75ca5b22260ef7 first.
Queued for 4.4. I've just grabbed the extra spellcheck fix as well.

--
Thanks,
Sasha

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