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Commit 77a2b37d authored by Steven Rostedt's avatar Steven Rostedt Committed by Thomas Gleixner
Browse files

ftrace: startup tester on dynamic tracing. 



This patch adds a startup self test on dynamic code modification
and filters. The test filters on a specific function, makes sure that
no other function is traced, exectutes the function, then makes sure that
the function is traced.

This patch also fixes a slight bug with the ftrace selftest, where
tracer_enabled was not being set.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 7bd2f24c

include/linux/ftrace.h

+2 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ struct dyn_ftrace { 
};



int ftrace_force_update(void);

void ftrace_set_filter(unsigned char *buf, int len, int reset);



/* defined in arch */

extern int ftrace_ip_converted(unsigned long ip);
@@ -70,6 +71,7 @@ extern void ftrace_call(void); 
extern void mcount_call(void);

#else

# define ftrace_force_update() ({ 0; })

# define ftrace_set_filter(buf, len, reset) do { } while (0)

#endif



static inline void tracer_disable(void)

kernel/trace/ftrace.c

+19 −0
Original line number Diff line number Diff line
@@ -1010,6 +1010,25 @@ ftrace_filter_write(struct file *file, const char __user *ubuf, 
	return ret;

}



/**

 * ftrace_set_filter - set a function to filter on in ftrace

 * @buf - the string that holds the function filter text.

 * @len - the length of the string.

 * @reset - non zero to reset all filters before applying this filter.

 *

 * Filters denote which functions should be enabled when tracing is enabled.

 * If @buf is NULL and reset is set, all functions will be enabled for tracing.

 */

notrace void ftrace_set_filter(unsigned char *buf, int len, int reset)

{

	mutex_lock(&ftrace_filter_lock);

	if (reset)

		ftrace_filter_reset();

	if (buf)

		ftrace_match(buf, len);

	mutex_unlock(&ftrace_filter_lock);

}



static int notrace

ftrace_filter_release(struct inode *inode, struct file *file)

{

kernel/trace/trace_selftest.c

+109 −4
Original line number Diff line number Diff line
@@ -99,6 +99,100 @@ static int trace_test_buffer(struct trace_array *tr, unsigned long *count) 
}



#ifdef CONFIG_FTRACE



#ifdef CONFIG_DYNAMIC_FTRACE



#define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func

#define __STR(x) #x

#define STR(x) __STR(x)

static int DYN_FTRACE_TEST_NAME(void)

{

	/* used to call mcount */

	return 0;

}



/* Test dynamic code modification and ftrace filters */

int trace_selftest_startup_dynamic_tracing(struct tracer *trace,

					   struct trace_array *tr,

					   int (*func)(void))

{

	unsigned long count;

	int ret;

	int save_ftrace_enabled = ftrace_enabled;

	int save_tracer_enabled = tracer_enabled;



	/* The ftrace test PASSED */

	printk(KERN_CONT "PASSED\n");

	pr_info("Testing dynamic ftrace: ");



	/* enable tracing, and record the filter function */

	ftrace_enabled = 1;

	tracer_enabled = 1;



	/* passed in by parameter to fool gcc from optimizing */

	func();



	/* update the records */

	ret = ftrace_force_update();

	if (ret) {

		printk(KERN_CONT ".. ftraced failed .. ");

		return ret;

	}



	/* filter only on our function */

	ftrace_set_filter(STR(DYN_FTRACE_TEST_NAME),

			  sizeof(STR(DYN_FTRACE_TEST_NAME)), 1);



	/* enable tracing */

	tr->ctrl = 1;

	trace->init(tr);

	/* Sleep for a 1/10 of a second */

	msleep(100);



	/* we should have nothing in the buffer */

	ret = trace_test_buffer(tr, &count);

	if (ret)

		goto out;



	if (count) {

		ret = -1;

		printk(KERN_CONT ".. filter did not filter .. ");

		goto out;

	}



	/* call our function again */

	func();



	/* sleep again */

	msleep(100);



	/* stop the tracing. */

	tr->ctrl = 0;

	trace->ctrl_update(tr);

	ftrace_enabled = 0;



	/* check the trace buffer */

	ret = trace_test_buffer(tr, &count);

	trace->reset(tr);



	/* we should only have one item */

	if (!ret && count != 1) {

		printk(KERN_CONT ".. filter failed ..");

		ret = -1;

		goto out;

	}

 out:

	ftrace_enabled = save_ftrace_enabled;

	tracer_enabled = save_tracer_enabled;



	/* Enable tracing on all functions again */

	ftrace_set_filter(NULL, 0, 1);



	return ret;

}

#else

# define trace_selftest_startup_dynamic_tracing(trace, tr, func) ({ 0; })

#endif /* CONFIG_DYNAMIC_FTRACE */

/*

 * Simple verification test of ftrace function tracer.

 * Enable ftrace, sleep 1/10 second, and then read the trace
@@ -109,8 +203,13 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr) 
{

	unsigned long count;

	int ret;

	int save_ftrace_enabled = ftrace_enabled;

	int save_tracer_enabled = tracer_enabled;



	/* make sure functions have been recorded */

	/* make sure msleep has been recorded */

	msleep(1);



	/* force the recorded functions to be traced */

	ret = ftrace_force_update();

	if (ret) {

		printk(KERN_CONT ".. ftraced failed .. ");
@@ -119,6 +218,7 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr) 


	/* start the tracing */

	ftrace_enabled = 1;

	tracer_enabled = 1;



	tr->ctrl = 1;

	trace->init(tr);
@@ -136,8 +236,16 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr) 
	if (!ret && !count) {

		printk(KERN_CONT ".. no entries found ..");

		ret = -1;

		goto out;

	}



	ret = trace_selftest_startup_dynamic_tracing(trace, tr,

						     DYN_FTRACE_TEST_NAME);



 out:

	ftrace_enabled = save_ftrace_enabled;

	tracer_enabled = save_tracer_enabled;



	return ret;

}

#endif /* CONFIG_FTRACE */
@@ -415,6 +523,3 @@ trace_selftest_startup_sched_switch(struct tracer *trace, struct trace_array *tr 
	return ret;

}

#endif /* CONFIG_CONTEXT_SWITCH_TRACER */
 


#ifdef CONFIG_DYNAMIC_FTRACE

#endif /* CONFIG_DYNAMIC_FTRACE */