linux-kernel - Re: [PATCH 1/3] powerpc/vdso: augment VDSO32 functions to support 64 bits build

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Message-ID: <20211221193608.GD614@gate.crashing.org>
Date:   Tue, 21 Dec 2021 13:36:08 -0600
From:   Segher Boessenkool <segher@...nel.crashing.org>
To:     Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        "masahiroy@...nel.org" <masahiroy@...nel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] powerpc/vdso: augment VDSO32 functions to support 64 bits build

On Tue, Dec 21, 2021 at 05:49:33PM +0000, Christophe Leroy wrote:
> diff --git a/arch/powerpc/kernel/vdso32/datapage.S b/arch/powerpc/kernel/vdso32/datapage.S
> index 65244416ab94..db8e167f0166 100644
> --- a/arch/powerpc/kernel/vdso32/datapage.S
> +++ b/arch/powerpc/kernel/vdso32/datapage.S
> @@ -30,11 +30,15 @@ V_FUNCTION_BEGIN(__kernel_get_syscall_map)
>  	mr.	r4,r3
>  	get_datapage	r3
>  	mtlr	r12
> +#ifdef __powerpc64__
> +	addi	r3,r3,CFG_SYSCALL_MAP64
> +#else
>  	addi	r3,r3,CFG_SYSCALL_MAP32
> +#endif
> +	crclr	cr0*4+so
>  	beqlr
>  	li	r0,NR_syscalls
>  	stw	r0,0(r4)
> -	crclr	cr0*4+so
>  	blr

This now clears cr0.3 if r3 is zero on entry.  Is that on purpose?

Rest looks good.

Reviewed-by: Segher Boessenkool <segher@...nel.crashing.org>


Segher