xtensa: implement fake NMI
In case perf IRQ is the highest of the medium-level IRQs, and is alone
on its level, it may be treated as NMI:
- LOCKLEVEL is defined to be one level less than EXCM level,
- IRQ masking never lowers current IRQ level,
- new fake exception cause code, EXCCAUSE_MAPPED_NMI is assigned to that
IRQ; new second level exception handler, do_nmi, assigned to it
handles it as NMI,
- atomic operations in configurations without s32c1i still need to mask
all interrupts.
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
diff --git a/arch/xtensa/kernel/perf_event.c b/arch/xtensa/kernel/perf_event.c
index b44df3c..54f0118 100644
--- a/arch/xtensa/kernel/perf_event.c
+++ b/arch/xtensa/kernel/perf_event.c
@@ -359,7 +359,7 @@
local_irq_restore(flags);
}
-static irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id)
+irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id)
{
irqreturn_t rc = IRQ_NONE;
struct xtensa_pmu_events *ev = this_cpu_ptr(&xtensa_pmu_events);
@@ -436,10 +436,14 @@
int irq = irq_create_mapping(NULL, XCHAL_PROFILING_INTERRUPT);
perf_cpu_notifier(xtensa_pmu_notifier);
+#if XTENSA_FAKE_NMI
+ enable_irq(irq);
+#else
ret = request_irq(irq, xtensa_pmu_irq_handler, IRQF_PERCPU,
"pmu", NULL);
if (ret < 0)
return ret;
+#endif
ret = perf_pmu_register(&xtensa_pmu, "cpu", PERF_TYPE_RAW);
if (ret)