Re: [PATCH] x86, AMD: Correct F15h IC aliasing issue

From: Ray Lee
Date: Tue Jul 26 2011 - 01:59:20 EST


On Mon, Jul 25, 2011 at 2:53 PM, Borislav Petkov <bp@xxxxxxxxx> wrote:
>
> On Mon, Jul 25, 2011 at 04:06:45PM -0400, Ingo Molnar wrote:
> >
> > * Borislav Petkov <bp@xxxxxxxxx> wrote:
> >
> > > So yeah, the simpler fix works for processes mapping libraries in
> > > the same order but not for processes mapping a subset of libraries
> > > in a different order.
> >
> > but what is the proportion of 'good' versus bad alignment of
> > libraries, could you collect some stats on a representative enough,
> > fully booted up Linux system?
> >
> > Are only 1% of mappings 'bad'? 5%? 10%? 50%? We have no idea and the
> > actual number matters a lot.
>
> Actually, it's hard to say what is a 'good' and 'bad' allocation. If
> they don't alias, they're always good :).

Count the number of aliases per total mappings, and report that as a
failure percentage? It doesn't have to be a perfect metric, it just
needs to be a meaningful and repeatable one.
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