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 <fweis...@gmail.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Li Zhong <zh...@linux.vnet.ibm.com>
Cc: Mike Galbraith <efa...@gmx.de>
Cc: Kevin Hilman <khil...@linaro.org>
---
include/trace/events/context_tracking.h | 58 +++++++++++++++++++++++++++++++
kernel/context_tracking.c | 5 +++
2 files changed, 63 insertions(+), 0 deletions(-)
create mode 100644 include/trace/events/context_tracking.h
diff --git a/include/trace/events/context_tracking.h
b/include/trace/events/context_tracking.h
new file mode 100644
index 0000000..ce8007c
--- /dev/null
+++ b/include/trace/events/context_tracking.h
@@ -0,0 +1,58 @@
+#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>
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index ef21e4f..688efe4 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 @@ 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);
}
--
1.7.5.4
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