Messages in this thread | | | Date | Wed, 14 Jul 2010 12:14:01 -0700 | Subject | Re: [patch 1/2] x86_64 page fault NMI-safe | From | Linus Torvalds <> |
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On Wed, Jul 14, 2010 at 11:46 AM, Ingo Molnar <mingo@elte.hu> wrote: >> NMI entry: > > I think at this point [NMI re-entry] we've corrupted the top of the NMI kernel > stack already, due to entering via the IST stack mechanism, which is > non-nesting and which enters at the same point - right?
Yeah, you're right, but we could easily fix that up. We know we don't need any stack for the nested case, so all we would need to do is to just subtract a small bit off %rsp, and copy the three words or so to create a "new" stack for the non-nested case.
> We could solve that by copying that small stack frame off before entering the > 'generic' NMI routine - but it all feels a bit pulled in by the hair.
Why? It's much cleaner than making the _real_ codepaths much worse.
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