Re: [RFC PATCH v2 10/11] powerpc: Support to replay PMIs

On Mon, 2016-08-01 at 18:07 +1000, Nicholas Piggin wrote:

quoted

+static inline unsigned long soft_irq_set_level(int value)
+{
+     unsigned long flags, zero;
+
+     asm volatile(
+             "li %1,%3; lbz %0,%2(13); stb %1,%2(13)"
+             : "=r" (flags), "=&r" (zero)
+             : "i" (offsetof(struct paca_struct, soft_enabled)),\
+               "i" (value)
+             : "memory");
+
+     return flags;
+}

I would add a WARN_ON (possibly under control
of CONFIG_TRACE_IRQFLAGS(*) to verify we only ever use this to make
interrupts "less enabled".

(*) Or check if distros use CONFIG_TRACE_IRQFLAGS these days, then
create a new CONFIG_DEBUG_IRQ or something like that, and also move
the other use of CONFIG_TRACE_IRQFLAGS in local_irq_restore that
checks the msr as we really don't want that in production kernels.

Cheers,
Ben.