[PATCH 12/14] powerpc/64s: system call avoid setting MSR[RI] until we set MSR[EE]

[Christophe Leroy]

Le 15/03/2021 à 23:04, Nicholas Piggin a écrit :
> This extends the MSR[RI]=0 window a little further into the system
> call in order to pair RI and EE enabling with a single mtmsrd.

Time ago, I proposed to delay that on PPC32 and Michael objected, see 
https://patchwork.ozlabs.org/project/linuxppc-dev/patch/9f9dd859d571e324c7412ed9db9da8cfba678257.1548956511.git.christophe.leroy@c-s.fr/


> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
>   arch/powerpc/kernel/exceptions-64s.S | 2 --
>   arch/powerpc/kernel/interrupt_64.S   | 6 +++---
>   2 files changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index bd0c82ac9de5..2f14ac3c377c 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -1999,8 +1999,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE)
>   	mtctr	r10
>   	bctr
>   	.else
> -	li	r10,MSR_RI
> -	mtmsrd 	r10,1			/* Set RI (EE=0) */
>   #ifdef CONFIG_RELOCATABLE
>   	__LOAD_HANDLER(r10, system_call_common)
>   	mtctr	r10
> diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S
> index f28f41a1a85a..eef61800f734 100644
> --- a/arch/powerpc/kernel/interrupt_64.S
> +++ b/arch/powerpc/kernel/interrupt_64.S
> @@ -311,10 +311,10 @@ END_BTB_FLUSH_SECTION
>   	 * nothing pending. system_call_exception() will call
>   	 * trace_hardirqs_off().
>   	 */
> -	li	r11,IRQS_ALL_DISABLED
> -	li	r12,PACA_IRQ_HARD_DIS
> +	li	r11,IRQS_DISABLED
> +	li	r12,-1 /* Set MSR_EE and MSR_RI */
>   	stb	r11,PACAIRQSOFTMASK(r13)
> -	stb	r12,PACAIRQHAPPENED(r13)
> +	mtmsrd	r12,1
>   
>   	ENTER_KERNEL_SECURITY_FALLBACK
>   
>