Re: [RFC PATCH 1/9] uaccess: Make copy_from_user_nmi() globally available

Frederic Weisbecker
2010-10-13T14:47:43Z

On Wed, Oct 13, 2010 at 09:15:56AM +0200, Peter Zijlstra wrote:
> On Wed, 2010-10-13 at 07:06 +0200, Frederic Weisbecker wrote:
> > In order to support user stack dump safely in perf samples from
> > generic code, export copy_from_user_nmi() from x86 and make it
> > generally available. For most archs it will map to
> > copy_from_user_inatomic, but for x86 we need to take care of
> > not faulting from NMIs.
> >
> > Since perf is the first user for now, let the overriden x86
> > implementation in the perf source file.
>
> It might make sense to call it copy_from_user_gup() because that's
> bascially what it does, it doesn't rely on NMI context anymore, its just
> NMI-safe.
>
> Its a best effort software page table walk, and with the stacked
> kmap_atomic bits Andrew took it should work from any context.

Ok, I'll do the rename. Does that work on any arch?

Thanks.