Re: [PATCH v2 19/21] arm64: entry: The great stack switcheroo

[Linus Walleij]

On Thu, Oct 1, 2026 at 9:27 AM Will Deacon <will@xxxxxxxxxx> wrote:
> On Wed, Sep 30, 2026 at 11:36:35PM +0200, Linus Walleij wrote:
> > On Fri, Sep 18, 2026 at 6:15 PM Will Deacon <will@xxxxxxxxxx> wrote:
> >
> > > With the kernel stack pointer in SP_EL1 and the overflow stack pointer
> > > in SP_EL0, it is now straightforward to switch between the two on
> > > exception entry from EL1 by writing to SPSel. However, since exception
> > > entry sets PSTATE.SP to 1 (selecting SP_EL1 as the stack pointer),
> > > repurposing the overflow stack as a more general kernel exception stack
> > > would require writing to SPSel on every exception entry from the kernel.
> > >
> > > Switch things around so that the overflow stack resides in SP_EL1, with
> > > the kernel stack residing in SP_EL0.
> > >
> > > Signed-off-by: Will Deacon <will@xxxxxxxxxx>
> >
> > This patch gives me panic, and as can be seen from the review
> > comments need some love...
>
> Please can you share the panic message? I'll definitely be reworking
> this based on the review comments, but if there's a bug it would be
> great to see the details now!

Haha. I was not referring to the kernel function but the emotion ;D

Yours,
Linus Walleij