Re: [RFC PATCH] asm/generic: introduce if_nospec and nospec_barrier

Pavel Machek
2018-01-04T19:39:40Z

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On Thu 2018-01-04 02:47:51, Jiri Kosina wrote:
> On Thu, 4 Jan 2018, Alan Cox wrote:
>
> > > If the CPU speculation can cause these kinds of side-effects, it just must
> > > not happen, full stop.
> >
> > At which point your performance will resemble that of a 2012 atom
> > processor at best.
>
> You know what? I'd be completely fine with that, if it's traded for "my
> ssh and internet banking keys are JUST MINE, ok?" :)

Agreed.

For kernel, we may be able to annonate "tainted" pointers. But then
there's quite a lot of code in userspace... What will need to be
modified? Just JITs? Setuid programs?

And we can get part of the performance back by adding more of
SMT... AFAICT.

Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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