Re: [PATCH v5 06/20] x86/decompressor: Store boot_params pointer in callee save register

[Ard Biesheuvel]

On Mon, 10 Jul 2023 at 11:07, Borislav Petkov <bp@xxxxxxxxx> wrote:
>
> On Wed, Jun 07, 2023 at 09:23:28AM +0200, Ard Biesheuvel wrote:
> > Instead of pushing and popping %RSI several times to preserve the struct
> > boot_params pointer across the execution of the startup code, move it
> > into a callee save register before the first call into C, and copy it
> > back when needed.
> >
> > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
> > ---
> >  arch/x86/boot/compressed/head_64.S | 34 +++++++-------------
> >  1 file changed, 11 insertions(+), 23 deletions(-)
>
> I like that.
>
> We do a similar dance in arch/x86/kernel/head_64.S. Care to fix that
> too, in a separate patch?
>

I already did, actually, but I dropped it from this series because it
was getting too long, and not essential for the overall goal of the
changes.

https://lore.kernel.org/all/20230602101313.3557775-19-ardb@xxxxxxxxxx/