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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>
This commit is contained in:
Frederic Weisbecker 2013-07-11 20:27:43 +02:00
parent 73d424f9af
commit 1b6a259aa5
2 changed files with 63 additions and 0 deletions
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58
include/trace/events/context_tracking.h Normal file
View File

@ -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>

5
kernel/context_tracking.c
View File

@ -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);
}