[PATCH 04/14] powerpc/rtas: Call enter_rtas with MSR[EE] disabled

[Laurent Dufour]

On 08/03/2022, 14:50:37, Nicholas Piggin wrote:
> Disable MSR[EE] in C code rather than asm.
> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>

FWIW,
Reviewed-by: Laurent Dufour <ldufour at linux.ibm.com>

> ---
>  arch/powerpc/kernel/rtas.c       |  4 ++++
>  arch/powerpc/kernel/rtas_entry.S | 17 +----------------
>  2 files changed, 5 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
> index 733e6ef36758..6b5892d6a56b 100644
> --- a/arch/powerpc/kernel/rtas.c
> +++ b/arch/powerpc/kernel/rtas.c
> @@ -49,6 +49,10 @@ void enter_rtas(unsigned long);
>  
>  static inline void do_enter_rtas(unsigned long args)
>  {
> +	BUG_ON(!irqs_disabled());
> +
> +	hard_irq_disable(); /* Ensure MSR[EE] is disabled on PPC64 */
> +
>  	enter_rtas(args);
>  
>  	srr_regs_clobbered(); /* rtas uses SRRs, invalidate */
> diff --git a/arch/powerpc/kernel/rtas_entry.S b/arch/powerpc/kernel/rtas_entry.S
> index 6fa10eb49a9c..45fa661c2ff6 100644
> --- a/arch/powerpc/kernel/rtas_entry.S
> +++ b/arch/powerpc/kernel/rtas_entry.S
> @@ -24,8 +24,6 @@ _GLOBAL(enter_rtas)
>  	lwz	r4,RTASBASE(r4)
>  	mfmsr	r9
>  	stw	r9,8(r1)
> -	LOAD_REG_IMMEDIATE(r0,MSR_KERNEL)
> -	mtmsr	r0	/* disable interrupts so SRR0/1 don't get trashed */
>  	li	r9,MSR_KERNEL & ~(MSR_IR|MSR_DR)
>  	mtlr	r6
>  	stw	r1, THREAD + RTAS_SP(r2)
> @@ -87,20 +85,7 @@ _GLOBAL(enter_rtas)
>  	li	r0,0
>  	mtcr	r0
>  
> -#ifdef CONFIG_BUG
> -	/* There is no way it is acceptable to get here with interrupts enabled,
> -	 * check it with the asm equivalent of WARN_ON
> -	 */
> -	lbz	r0,PACAIRQSOFTMASK(r13)
> -1:	tdeqi	r0,IRQS_ENABLED
> -	EMIT_WARN_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING
> -#endif
> -
> -	/* Hard-disable interrupts */
>  	mfmsr	r6
> -	rldicl	r7,r6,48,1
> -	rotldi	r7,r7,16
> -	mtmsrd	r7,1
>  
>  	/* Unfortunately, the stack pointer and the MSR are also clobbered,
>  	 * so they are saved in the PACA which allows us to restore
> @@ -124,7 +109,7 @@ _GLOBAL(enter_rtas)
>  	andc	r6,r0,r9
>  
>  __enter_rtas:
> -	sync				/* disable interrupts so SRR0/1 */
> +	sync				/* disable RI so SRR0/1 */
>  	mtmsrd	r0			/* don't get trashed */
>  
>  	LOAD_REG_ADDR(r4, rtas)