linux-kernel - Re: [PATCH v5 10/22] powerpc/syscall: Use is_compat

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Date:   Tue, 09 Feb 2021 11:29:15 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Michael Ellerman <mpe@...erman.id.au>, msuchanek@...e.de,
        Paul Mackerras <paulus@...ba.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v5 10/22] powerpc/syscall: Use is_compat_task()

Excerpts from Christophe Leroy's message of February 9, 2021 1:10 am:
> Instead of hard comparing task flags with _TIF_32BIT, use
> is_compat_task(). The advantage is that it returns 0 on PPC32
> allthough _TIF_32BIT is always set.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>

Reviewed-by: Nicholas Piggin <npiggin@...il.com>


> ---
>  arch/powerpc/kernel/interrupt.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
> index 2dac4d2bb1cf..46fd195ca659 100644
> --- a/arch/powerpc/kernel/interrupt.c
> +++ b/arch/powerpc/kernel/interrupt.c
> @@ -2,6 +2,8 @@
>  
>  #include <linux/context_tracking.h>
>  #include <linux/err.h>
> +#include <linux/compat.h>
> +
>  #include <asm/asm-prototypes.h>
>  #include <asm/kup.h>
>  #include <asm/cputime.h>
> @@ -118,7 +120,7 @@ notrace long system_call_exception(long r3, long r4, long r5,
>  	/* May be faster to do array_index_nospec? */
>  	barrier_nospec();
>  
> -	if (unlikely(is_32bit_task())) {
> +	if (unlikely(is_compat_task())) {
>  		f = (void *)compat_sys_call_table[r0];
>  
>  		r3 &= 0x00000000ffffffffULL;
> -- 
> 2.25.0
> 
>