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: Frederic 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>
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index c178226..247091b 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -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 @@
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 @@
*/
rcu_user_exit();
vtime_user_exit(current);
+ trace_user_exit(0);
}
__this_cpu_write(context_tracking.state, IN_KERNEL);
}