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| author | Nicholas Piggin <npiggin@gmail.com> | 2021-10-05 00:56:41 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-10-07 19:54:55 +1100 |
| commit | 768c47010392ece9766a56479b4e0cf04a536916 (patch) | |
| tree | f2c12ed1c9e28d67818d167fd6fe6e010b0c6043 /arch | |
| parent | ff058a8ada5df0d84e5537cfaf89d06d71501580 (diff) | |
| download | linux-stable-768c47010392ece9766a56479b4e0cf04a536916.tar.gz linux-stable-768c47010392ece9766a56479b4e0cf04a536916.tar.bz2 linux-stable-768c47010392ece9766a56479b4e0cf04a536916.zip | |
powerpc/64/interrupt: Reconcile soft-mask state in NMI and fix false BUG
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.
This doesn't fix a known problem -- the change that was fixed by commit
4ec5feec1ad02 ("powerpc/64s: Make NMI record implicitly soft-masked code
as irqs disabled") was the addition of a warning in the soft-nmi
watchdog interrupt which can never actually fire when MSR[EE]=0. However
it may be important if NMI handlers grow more code, and it's less
surprising to anything using 'regs' - (I tripped over this when working
in the area).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211004145642.1331214-5-npiggin@gmail.com
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/include/asm/interrupt.h | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h index 6b800d3e2681..b894b7169706 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 */ |