tracing, genirq: add irq enter and exit trace events

Impact: add new tracepoints

Add them to the generic IRQ code, that way every architecture
gets these new tracepoints, not just x86.

Using Steve's new 'TRACE_FORMAT', I can get function graph
trace as follows using the original two IRQ tracepoints:

 3)               |    handle_IRQ_event() {
 3)               |    /* (irq_handler_entry) irq=28 handler=eth0 */
 3)               |    e1000_intr_msi() {
 3)   2.460 us    |      __napi_schedule();
 3)   9.416 us    |    }
 3)               |    /* (irq_handler_exit) irq=28 handler=eth0 return=handled */
 3) + 22.935 us   |  }

Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/trace/irq.h

@@ -0,0 +1,9 @@
+#ifndef _TRACE_IRQ_H
+#define _TRACE_IRQ_H
+
+#include <linux/interrupt.h>
+#include <linux/tracepoint.h>
+
+#include <trace/irq_event_types.h>
+
+#endif

include/trace/irq_event_types.h

@@ -0,0 +1,17 @@
+
+/* use <trace/irq.h> instead */
+#ifndef TRACE_FORMAT
+# error Do not include this file directly.
+# error Unless you know what you are doing.
+#endif
+
+TRACE_FORMAT(irq_handler_entry,
+	TPPROTO(int irq, struct irqaction *action),
+	TPARGS(irq, action),
+	TPFMT("irq=%d handler=%s", irq, action->name));
+
+TRACE_FORMAT(irq_handler_exit,
+	TPPROTO(int irq, struct irqaction *action, int ret),
+	TPARGS(irq, action, ret),
+	TPFMT("irq=%d handler=%s return=%s",
+		irq, action->name, ret ? "handled" : "unhandled"));

kernel/irq/handle.c

@@ -17,6 +17,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/rculist.h>
 #include <linux/hash.h>
+#include <trace/irq.h>
 
 #include "internals.h"
 
@@ -316,6 +317,9 @@ irqreturn_t no_action(int cpl, void *dev_id)
 	return IRQ_NONE;
 }
 
+DEFINE_TRACE(irq_handler_entry);
+DEFINE_TRACE(irq_handler_exit);
+
 /**
  * handle_IRQ_event - irq action chain handler
  * @irq:	the interrupt number
@@ -332,7 +336,9 @@ irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
 		local_irq_enable_in_hardirq();
 
 	do {
+		trace_irq_handler_entry(irq, action);
 		ret = action->handler(irq, action->dev_id);
+		trace_irq_handler_exit(irq, action, ret);
 		if (ret == IRQ_HANDLED)
 			status |= action->flags;
 		retval |= ret;

kernel/trace/events.c

@@ -6,8 +6,10 @@
 
 /* trace/<type>.h here */
 #include <trace/sched.h>
+#include <trace/irq.h>
 
 #include "trace_events.h"
 
 /* trace/<type>_event_types.h here */
 #include <trace/sched_event_types.h>
+#include <trace/irq_event_types.h>