Re: [PATCH] x86-64: espfix for 64-bit mode *PROTOTYPE*

Andrew Lutomirski
2014-04-23T01:23:48Z

On Tue, Apr 22, 2014 at 6:17 PM, H. Peter Anvin <hpa@linux.intel.com> wrote:
> Another spin of the prototype. This one avoids the espfix for anything
> but #GP, and avoids save/restore/saving registers... one can wonder,
> though, how much that actually matters in practice.
>
> It still does redundant SWAPGS on the slow path. I'm not sure I
> personally care enough to optimize that, as it means some fairly
> significant restructuring of some of the code paths. Some of that
> restructuring might actually be beneficial, but still...
>

What's the to_dmesg thing for?

It looks sane, although I haven't checked the detailed register manipulation.

Users of big systems may complain when every single CPU lines up for
that mutex. Maybe no one cares.

--Andy