[PATCH v4] arm64: smccc: Support SMCCC v1.3 SVE register saving hint

[Ard Biesheuvel]

On Thu, 27 May 2021 at 10:18, Will Deacon <will at kernel.org> wrote:
>
> On Thu, May 27, 2021 at 09:09:53AM +0100, Will Deacon wrote:
> > On Thu, May 27, 2021 at 12:02:48AM +0100, Mark Brown wrote:
> > > On Wed, May 26, 2021 at 10:31:29PM +0100, Will Deacon wrote:
> > > > On Mon, May 24, 2021 at 11:42:53AM +0100, Mark Brown wrote:
> > >
> > > > >  drivers/firmware/smccc/smccc.c |  4 ++++
> > > > >  include/linux/arm-smccc.h      | 24 ++++++++++++++++++++++--
> > > > >  3 files changed, 52 insertions(+), 2 deletions(-)
> > >
> > > > This fails to build for me:
> > >
> > > Interesting...  which toolchain are you using here?
> >
> > That's a good question.
> >
> > /me digs into scripts
> >
> > I think it's:
> >
> > gcc version 9.2.1 20191025 (GNU Toolchain for the A-profile Architecture 9.2-2019.12 (arm-9.10))
>
> Duh, I suppose you're probably more interested in the assembler:
>
> GNU assembler (GNU Toolchain for the A-profile Architecture 9.2-2019.12 (arm-9.10)) 2.33.1.20191209
>

Didn't we run into this before?

IIRC, lr was never defined as a register alias for x30, which is why
we have the .req in 8f5c9037a55b. This caused breakage when the GNU
folks tried to add the lr alias, as the .req would be rejected now, so
they removed it again. (I might be misremembering, but something along
those lines did occur)

In summary, let's just use x30 in the clobber list and be done with it.