From: Michael Ellerman <mpe@ellerman•id.au>
To: Nicholas Piggin <npiggin@gmail•com>, linuxppc-dev@lists•ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail•com>
Subject: Re: [PATCH 4/9] powerpc/64s: SLB miss handler avoid r3 save/restore
Date: Mon, 19 Jun 2017 14:48:37 +1000 [thread overview]
Message-ID: <87tw3cvaze.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20170521131550.25813-5-npiggin@gmail.com>
Nicholas Piggin <npiggin@gmail•com> writes:
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index 486e205cc762..6ba4c4c6ae69 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -625,6 +625,9 @@ EXC_COMMON_BEGIN(slb_miss_realmode)
> stw r9,PACA_EXSLB+EX_CCR(r13) /* save CR in exc. frame */
> std r10,PACA_EXSLB+EX_LR(r13) /* save LR */
>
> + andi. r11,r11,MSR_RI /* check for unrecoverable exception */
> + beq- 2f
> +
> crset 4*cr0+eq
> #ifdef CONFIG_PPC_STD_MMU_64
> BEGIN_MMU_FTR_SECTION
> @@ -638,9 +641,6 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_RADIX)
>
> beq- 8f /* if bad address, make full stack frame */
>
> - andi. r10,r12,MSR_RI /* check for unrecoverable exception */
> - beq- 2f
> -
Moving that check before slb_allocate_realmode() makes me a bit nervous.
It's already a bug if we're taking an SLB miss with RI off, but I'm
worried that by not doing the SLB allocate we might turn what would be a
regular oops into an infinite loop of SLB misses. But my brain is too
sleep deprived today to decide either way.
cheers
next prev parent reply other threads:[~2017-06-19 4:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-21 13:15 [PATCH 0/9] Reduce PACA save areas Nicholas Piggin
2017-05-21 13:15 ` [PATCH 1/9] powerpc/64s: slb_allocate_realmode() preserve r3 Nicholas Piggin
2017-06-22 13:12 ` [1/9] " Michael Ellerman
2017-05-21 13:15 ` [PATCH 2/9] powerpc/64s: SLB miss handler avoid saving faulting address into EX_DAR Nicholas Piggin
2017-05-21 13:15 ` [PATCH 3/9] powerpc/64s: SLB miss already has CTR saved for relocatable kernel Nicholas Piggin
2017-06-19 11:45 ` Michael Ellerman
2017-06-19 17:20 ` Nicholas Piggin
2017-05-21 13:15 ` [PATCH 4/9] powerpc/64s: SLB miss handler avoid r3 save/restore Nicholas Piggin
2017-06-19 4:48 ` Michael Ellerman [this message]
2017-06-19 16:54 ` Nicholas Piggin
2017-05-21 13:15 ` [PATCH 5/9] powerpc/64s: paca add EX_SIZE definition for exception save areas Nicholas Piggin
2017-05-21 13:15 ` [PATCH 6/9] powerpc/64s: paca EX_SRR0 is unused, remove it Nicholas Piggin
2017-05-21 13:15 ` [PATCH 7/9] powerpc/64s: paca EX_LR can be merged with EX_DAR Nicholas Piggin
2017-05-21 13:15 ` [PATCH 8/9] powerpc/64s: paca EX_R3 " Nicholas Piggin
2017-05-21 13:15 ` [PATCH 9/9] powerpc/64s: paca EX_CTR is not used with !RELOCATABLE, remove it Nicholas Piggin
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