Re: [PATCH v2 00/21] arm64: Move overflow sp into SP_EL1 and kernel sp into SP_EL0

[Will Deacon]

On Wed, Sep 30, 2026 at 11:42:51PM +0200, Linus Walleij wrote:
> On Fri, Sep 18, 2026 at 6:14 PM Will Deacon <will@xxxxxxxxxx> wrote:
> 
> > This is version two of the kernel stack juggling patches I previously
> > posted here:
> >
> >   https://lore.kernel.org/r/20260907164247.17223-1-will@xxxxxxxxxx
> >
> > Changes since v1 include:
> >   * Fixed suspend/resume paths to handle the stack pointers properly
> >   * Fixed restoration of ptrauth keys on resume
> >   * Added tags
> 
> Overall I like what I see, but can we split it in two... like first the patches
> up to fixing the overflow handling using SP_EL0 and finalize that?

Yes, that makes sense (and thanks for going through it). The whole thing
is bisectable, so lemme go through the feedback I've got so far and send
out a prefix that we could consider merging as preparatory work.

> Hopefully Usama can test just that part and see if it has a lesser
> performance impact as well.

I'd like to see those numbers at various points during the series, tbh,
so we can rule out any stack-protector changes etc.

Will