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Commit 1b6a259a authored by Frederic Weisbecker's avatar Frederic Weisbecker
Browse files

context_tracking: User/kernel broundary cross trace events 



This can be useful to track all kernel/user round trips.
And it's also helpful to debug the context tracking subsystem.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
parent 73d424f9

include/trace/events/context_tracking.h

0 → 100644
+58 −0
Original line number Diff line number Diff line 
#undef TRACE_SYSTEM

#define TRACE_SYSTEM context_tracking



#if !defined(_TRACE_CONTEXT_TRACKING_H) || defined(TRACE_HEADER_MULTI_READ)

#define _TRACE_CONTEXT_TRACKING_H



#include <linux/tracepoint.h>



DECLARE_EVENT_CLASS(context_tracking_user,



	TP_PROTO(int dummy),



	TP_ARGS(dummy),



	TP_STRUCT__entry(

		__field( int,	dummy	)

	),



	TP_fast_assign(

		__entry->dummy		= dummy;

	),



	TP_printk("%s", "")

);



/**

 * user_enter - called when the kernel resumes to userspace

 * @dummy:	dummy arg to make trace event macro happy

 *

 * This event occurs when the kernel resumes to userspace  after

 * an exception or a syscall.

 */

DEFINE_EVENT(context_tracking_user, user_enter,



	TP_PROTO(int dummy),



	TP_ARGS(dummy)

);



/**

 * user_exit - called when userspace enters the kernel

 * @dummy:	dummy arg to make trace event macro happy

 *

 * This event occurs when userspace enters the kernel through

 * an exception or a syscall.

 */

DEFINE_EVENT(context_tracking_user, user_exit,



	TP_PROTO(int dummy),



	TP_ARGS(dummy)

);





#endif /*  _TRACE_CONTEXT_TRACKING_H */



/* This part must be outside protection */

#include <trace/define_trace.h>

kernel/context_tracking.c

+5 −0
Original line number Diff line number Diff line
@@ -20,6 +20,9 @@ 
#include <linux/hardirq.h>

#include <linux/export.h>



#define CREATE_TRACE_POINTS

#include <trace/events/context_tracking.h>



struct static_key context_tracking_enabled = STATIC_KEY_INIT_FALSE;

EXPORT_SYMBOL_GPL(context_tracking_enabled);
@@ -64,6 +67,7 @@ void context_tracking_user_enter(void) 
	local_irq_save(flags);

	if ( __this_cpu_read(context_tracking.state) != IN_USER) {

		if (__this_cpu_read(context_tracking.active)) {

			trace_user_enter(0);

			/*

			 * At this stage, only low level arch entry code remains and

			 * then we'll run in userspace. We can assume there won't be
@@ -159,6 +163,7 @@ void context_tracking_user_exit(void) 
			 */

			rcu_user_exit();

			vtime_user_exit(current);

			trace_user_exit(0);

		}

		__this_cpu_write(context_tracking.state, IN_KERNEL);

	}