Re: [PATCH] powerpc/40x: Fix assembler warning about r0

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 22/07/2020 à 04:24, Michael Ellerman a écrit :
> The assembler says:
>    arch/powerpc/kernel/head_40x.S:623: Warning: invalid register expression

I get exactly the same with head_32.S, for the exact same reason.

Christophe

> 
> It's objecting to the use of r0 as the RA argument. That's because
> when RA = 0 the literal value 0 is used, rather than the content of
> r0, making the use of r0 in the source potentially confusing.
> 
> Fix it to use a literal 0, the generated code is identical.
> 
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---
>   arch/powerpc/kernel/head_40x.S | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
> index 926bfa73586a..5b282d9965a5 100644
> --- a/arch/powerpc/kernel/head_40x.S
> +++ b/arch/powerpc/kernel/head_40x.S
> @@ -620,7 +620,7 @@ _ENTRY(saved_ksp_limit)
>   	ori	r6, r6, swapper_pg_dir@l
>   	lis	r5, abatron_pteptrs@h
>   	ori	r5, r5, abatron_pteptrs@l
> -	stw	r5, 0xf0(r0)	/* Must match your Abatron config file */
> +	stw	r5, 0xf0(0)	/* Must match your Abatron config file */
>   	tophys(r5,r5)
>   	stw	r6, 0(r5)
>   
>