Re: [PATCH v5 15/30] arm64/sve: Signal handling support

Will Deacon
2017-12-12T10:40:30Z

On Mon, Dec 11, 2017 at 11:23:09AM -0800, Kees Cook wrote:
> On Mon, Dec 11, 2017 at 6:07 AM, Will Deacon <will.deacon@arm.com> wrote:
> > On Thu, Dec 07, 2017 at 10:50:38AM -0800, Kees Cook wrote:
> >> My question is mainly: why not just use copy_*() everywhere instead?
> >> Having these things so spread out makes it fragile, and there's very
> >> little performance benefit from using __copy_*() over copy_*().
> >
> > I think that's more of a general question. Why not just remove the __
> > versions from the kernel entirely if they're not worth the perf?
>
> That has been something Linus has strongly suggested in the past, so
> I've kind of been looking for easy places to drop the __copy_*
> versions. :)

Tell you what then: I'll Ack the arm64 patch if it's part of a series
removing the thing entirely :p

I guess we'd still want to the validation of the whole sigframe though,
so we don't end up pushing half a signal stack before running into an
access_ok failure?

Will