[PATCH v3 35/51] trace,hardirq: No moar _rcuidle() tracing

[Peter Zijlstra]

Robot reported that trace_hardirqs_{on,off}() tickle the forbidden
_rcuidle() tracepoint through local_irq_{en,dis}able().

For 'sane' configs, these calls will only happen with RCU enabled and
as such can use the regular tracepoint. This also means it's possible
to trace them from NMI context again.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
 kernel/trace/trace_preemptirq.c |   21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

--- a/kernel/trace/trace_preemptirq.c
+++ b/kernel/trace/trace_preemptirq.c
@@ -20,6 +20,15 @@
 static DEFINE_PER_CPU(int, tracing_irq_cpu);
 
 /*
+ * ...
+ */
+#ifdef CONFIG_ARCH_WANTS_NO_INSTR
+#define trace(point)	trace_##point
+#else
+#define trace(point)	if (!in_nmi()) trace_##point##_rcuidle
+#endif
+
+/*
  * Like trace_hardirqs_on() but without the lockdep invocation. This is
  * used in the low level entry code where the ordering vs. RCU is important
  * and lockdep uses a staged approach which splits the lockdep hardirq
@@ -28,8 +37,7 @@ static DEFINE_PER_CPU(int, tracing_irq_c
 void trace_hardirqs_on_prepare(void)
 {
 	if (this_cpu_read(tracing_irq_cpu)) {
-		if (!in_nmi())
-			trace_irq_enable(CALLER_ADDR0, CALLER_ADDR1);
+		trace(irq_enable)(CALLER_ADDR0, CALLER_ADDR1);
 		tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1);
 		this_cpu_write(tracing_irq_cpu, 0);
 	}
@@ -40,8 +48,7 @@ NOKPROBE_SYMBOL(trace_hardirqs_on_prepar
 void trace_hardirqs_on(void)
 {
 	if (this_cpu_read(tracing_irq_cpu)) {
-		if (!in_nmi())
-			trace_irq_enable_rcuidle(CALLER_ADDR0, CALLER_ADDR1);
+		trace(irq_enable)(CALLER_ADDR0, CALLER_ADDR1);
 		tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1);
 		this_cpu_write(tracing_irq_cpu, 0);
 	}
@@ -63,8 +70,7 @@ void trace_hardirqs_off_finish(void)
 	if (!this_cpu_read(tracing_irq_cpu)) {
 		this_cpu_write(tracing_irq_cpu, 1);
 		tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1);
-		if (!in_nmi())
-			trace_irq_disable(CALLER_ADDR0, CALLER_ADDR1);
+		trace(irq_disable)(CALLER_ADDR0, CALLER_ADDR1);
 	}
 
 }
@@ -78,8 +84,7 @@ void trace_hardirqs_off(void)
 	if (!this_cpu_read(tracing_irq_cpu)) {
 		this_cpu_write(tracing_irq_cpu, 1);
 		tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1);
-		if (!in_nmi())
-			trace_irq_disable_rcuidle(CALLER_ADDR0, CALLER_ADDR1);
+		trace(irq_disable)(CALLER_ADDR0, CALLER_ADDR1);
 	}
 }
 EXPORT_SYMBOL(trace_hardirqs_off);