linux-kernel - Re: [PATCH v5 11/22] powerpc/syscall: Save r3 in regs->orig

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Message-Id: <1612834174.puqh8atps5.astroid@bobo.none>
Date:   Tue, 09 Feb 2021 11:29:41 +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 11/22] powerpc/syscall: Save r3 in regs->orig_r3

Excerpts from Christophe Leroy's message of February 9, 2021 1:10 am:
> Save r3 in regs->orig_r3 in system_call_exception()
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>

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

> ---
> v5: Removed the assembly one on SCV type system call
> ---
>  arch/powerpc/kernel/entry_64.S  | 2 --
>  arch/powerpc/kernel/interrupt.c | 2 ++
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
> index 33ddfeef4fe9..a91c2def165d 100644
> --- a/arch/powerpc/kernel/entry_64.S
> +++ b/arch/powerpc/kernel/entry_64.S
> @@ -108,7 +108,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_TM)
>  	li	r11,\trapnr
>  	std	r11,_TRAP(r1)
>  	std	r12,_CCR(r1)
> -	std	r3,ORIG_GPR3(r1)
>  	addi	r10,r1,STACK_FRAME_OVERHEAD
>  	ld	r11,exception_marker@toc(r2)
>  	std	r11,-16(r10)		/* "regshere" marker */
> @@ -278,7 +277,6 @@ END_BTB_FLUSH_SECTION
>  	std	r10,_LINK(r1)
>  	std	r11,_TRAP(r1)
>  	std	r12,_CCR(r1)
> -	std	r3,ORIG_GPR3(r1)
>  	addi	r10,r1,STACK_FRAME_OVERHEAD
>  	ld	r11,exception_marker@toc(r2)
>  	std	r11,-16(r10)		/* "regshere" marker */
> diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
> index 46fd195ca659..1a2dec49f811 100644
> --- a/arch/powerpc/kernel/interrupt.c
> +++ b/arch/powerpc/kernel/interrupt.c
> @@ -29,6 +29,8 @@ notrace long system_call_exception(long r3, long r4, long r5,
>  {
>  	syscall_fn f;
>  
> +	regs->orig_gpr3 = r3;
> +
>  	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
>  		BUG_ON(irq_soft_mask_return() != IRQS_ALL_DISABLED);
>  
> -- 
> 2.25.0
> 
>