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Date: Thu, 16 Aug 2018 17:19:46 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: Sarah Newman <srn@prgmr.com>
Cc: David Woodhouse <dwmw2@infradead.org>, stable@vger.kernel.org,
        "Durand Wesolowski, Jimmy" <jdw@amazon.de>,
        Juergen Gross <jgross@suse.com>,
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        Thomas Gleixner <tglx@linutronix.de>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [Xen-devel] [PATCH] x86/entry/64: Remove %ebx handling from
 error_entry/exit
Message-ID: <20180816151946.GH10648@kroah.com>
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On Fri, Aug 10, 2018 at 12:23:45AM -0700, Sarah Newman wrote:
> On 08/09/2018 05:41 AM, David Woodhouse wrote:
> > On Wed, 2018-08-08 at 10:35 -0700, Sarah Newman wrote:
> >> commit b3681dd548d06deb2e1573890829dff4b15abf46 upstream.
> >>
> >> This version applies to v4.9.
> > 
> > I think you can kill the 'xorl %ebx,%ebx' from error_entry too but yes,
> > this does want to go to 4.9 and earlier because the 'Fixes:' tag is a
> > bit of a lie — the problem existed before that, at least in theory.
> 
> The commit 2140a9942 "x86/entry/64: Relax pvops stub clobber
> specifications" was what removed the "movl %ebx, %eax" line later on
> originally, but it was the commit 3ac6d8c787b8 that removed the
> 'xorl %ebx,%ebx'. So these weren't matched.
> 
> I don't know if it's a concern, but if someone had gone to the effort of
> backporting the original commit 3ac6d8c787b83, adding the removal of
> 'xorl %ebx,%ebx' to this patch would create merge conflicts.
> For that reason and given the line is harmless, should it be left in?

I need some kind of agreement here for me to know what to do with this
patch...  {hint}

thanks,

greg k-h