From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH v1] powerpc/64/interrupt: Reconcile soft-mask state in NMI and fix false BUG
Date: Thu, 23 Sep 2021 00:49:53 +1000 [thread overview]
Message-ID: <20210922144953.352067-1-npiggin@gmail.com> (raw)
If a NMI hits early in an interrupt handler before the irq soft-mask
state is reconciled, that can cause a false-positive BUG with a
CONFIG_PPC_IRQ_SOFT_MASK_DEBUG assertion.
Remove that assertion and instead check the case that if regs->msr has
EE clear, then regs->softe should be marked as disabled so the irq state
looks correct to NMI handlers, the same as how it's fixed up in the
case it was implicit soft-masked.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/interrupt.h | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index b32ed910a8cf..b76ab848aa0d 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -265,13 +265,16 @@ static inline void interrupt_nmi_enter_prepare(struct pt_regs *regs, struct inte
local_paca->irq_soft_mask = IRQS_ALL_DISABLED;
local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
- if (is_implicit_soft_masked(regs)) {
- // Adjust regs->softe soft implicit soft-mask, so
- // arch_irq_disabled_regs(regs) behaves as expected.
+ if (!(regs->msr & MSR_EE) || is_implicit_soft_masked(regs)) {
+ /*
+ * Adjust regs->softe to be soft-masked if it had not been
+ * reconcied (e.g., interrupt entry with MSR[EE]=0 but softe
+ * not yet set disabled), or if it was in an implicit soft
+ * masked state. This makes arch_irq_disabled_regs(regs)
+ * behave as expected.
+ */
regs->softe = IRQS_ALL_DISABLED;
}
- if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
- BUG_ON(!arch_irq_disabled_regs(regs) && !(regs->msr & MSR_EE));
/* Don't do any per-CPU operations until interrupt state is fixed */
--
2.23.0
reply other threads:[~2021-09-22 14:50 UTC|newest]
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