Commit f9349a8f authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
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tracing/function-graph-tracer: make set_graph_function file support ftrace regex 



Impact: trace only functions matching a pattern

The set_graph_function file let one to trace only one or several
chosen functions and follow all their code flow.

Currently, only a constant function name is allowed so this patch
allows the ftrace_regex functions:

- matches all functions that end with "name":
  echo *name > set_graph_function

- matches all functions that begin with "name":
  echo name* > set_graph_function

- matches all functions that contains "name":
  echo *name* > set_graph_function

Example:

echo mutex* > set_graph_function

 0)               |  mutex_lock_nested() {
 0)   0.563 us    |    __might_sleep();
 0)   2.072 us    |  }
 0)               |  mutex_unlock() {
 0)   1.036 us    |    __mutex_unlock_slowpath();
 0)   2.433 us    |  }
 0)               |  mutex_unlock() {
 0)   0.691 us    |    __mutex_unlock_slowpath();
 0)   1.787 us    |  }
 0)               |  mutex_lock_interruptible_nested() {
 0)   0.548 us    |    __might_sleep();
 0)   1.945 us    |  }

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 64b36ca7

kernel/trace/ftrace.c

+38 −18
Original line number Diff line number Diff line
@@ -1895,6 +1895,10 @@ static void *g_start(struct seq_file *m, loff_t *pos) 


	mutex_lock(&graph_lock);



	/* Nothing, tell g_show to print all functions are enabled */

	if (!ftrace_graph_count && !*pos)

		return (void *)1;



	p = g_next(m, p, pos);



	return p;
@@ -1913,6 +1917,11 @@ static int g_show(struct seq_file *m, void *v) 
	if (!ptr)

		return 0;



	if (ptr == (unsigned long *)1) {

		seq_printf(m, "#### all functions enabled ####\n");

		return 0;

	}



	kallsyms_lookup(*ptr, NULL, NULL, NULL, str);



	seq_printf(m, "%s\n", str);
@@ -1966,38 +1975,51 @@ ftrace_graph_read(struct file *file, char __user *ubuf, 
}



static int

ftrace_set_func(unsigned long *array, int idx, char *buffer)

ftrace_set_func(unsigned long *array, int *idx, char *buffer)

{

	char str[KSYM_SYMBOL_LEN];

	struct dyn_ftrace *rec;

	struct ftrace_page *pg;

	int search_len;

	int found = 0;

	int j;

	int type, not;

	char *search;

	bool exists;

	int i;



	if (ftrace_disabled)

		return -ENODEV;



	/* decode regex */

	type = ftrace_setup_glob(buffer, strlen(buffer), &search, &not);

	if (not)

		return -EINVAL;



	search_len = strlen(search);



	mutex_lock(&ftrace_lock);

	do_for_each_ftrace_rec(pg, rec) {



		if (*idx >= FTRACE_GRAPH_MAX_FUNCS)

			break;



		if (rec->flags & (FTRACE_FL_FAILED | FTRACE_FL_FREE))

			continue;



		kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);

		if (strcmp(str, buffer) == 0) {

			/* Return 1 if we add it to the array */

			found = 1;

			for (j = 0; j < idx; j++)

				if (array[j] == rec->ip) {

					found = 0;

		if (ftrace_match_record(rec, search, search_len, type)) {

			/* ensure it is not already in the array */

			exists = false;

			for (i = 0; i < *idx; i++)

				if (array[i] == rec->ip) {

					exists = true;

					break;

				}

			if (found)

				array[idx] = rec->ip;

			goto out;

			if (!exists) {

				array[(*idx)++] = rec->ip;

				found = 1;

			}

		}

	} while_for_each_ftrace_rec();

 out:



	mutex_unlock(&ftrace_lock);



	return found ? 0 : -EINVAL;
@@ -2066,13 +2088,11 @@ ftrace_graph_write(struct file *file, const char __user *ubuf, 
	}

	buffer[index] = 0;



	/* we allow only one at a time */

	ret = ftrace_set_func(array, ftrace_graph_count, buffer);

	/* we allow only one expression at a time */

	ret = ftrace_set_func(array, &ftrace_graph_count, buffer);

	if (ret)

		goto out;



	ftrace_graph_count++;



	file->f_pos += read;



	ret = read;

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