powerpc/64: warn if local irqs are enabled in NMI or hardirq context

This can help catch bugs such as the one fixed by the previous change
to prevent _exception() from enabling irqs.

ppc32 could have a similar warning but it has no good config option to
debug this stuff (the test may be overkill to add for production
kernels).

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211004145642.1331214-4-npiggin@gmail.com

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 551b653..c4f1d6b 100644 (file)
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -229,6 +229,9 @@ notrace void arch_local_irq_restore(unsigned long mask)
                return;
        }
 
+       if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
+               WARN_ON_ONCE(in_nmi() || in_hardirq());
+
        /*
         * After the stb, interrupts are unmasked and there are no interrupts
         * pending replay. The restart sequence makes this atomic with
@@ -321,6 +324,9 @@ notrace void arch_local_irq_restore(unsigned long mask)
        if (mask)
                return;
 
+       if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
+               WARN_ON_ONCE(in_nmi() || in_hardirq());
+
        /*
         * From this point onward, we can take interrupts, preempt,
         * etc... unless we got hard-disabled. We check if an event