Commit 4c86bc53 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt (Google)
Browse files

tracing: Add :mod: command to enabled module events 

Add a :mod: command to enable only events from a given module from the
set_events file.

  echo '*:mod:<module>' > set_events

Or

  echo ':mod:<module>' > set_events

Will enable all events for that module. Specific events can also be
enabled via:

  echo '<event>:mod:<module>' > set_events

Or

  echo '<system>:<event>:mod:<module>' > set_events

Or

  echo '*:<event>:mod:<module>' > set_events

The ":mod:" keyword is consistent with the function tracing filter to
enable functions from a given module.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20250116143533.214496360@goodmis.org


Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 80c3e285

Documentation/trace/events.rst

+22 −0
Original line number Diff line number Diff line
@@ -55,6 +55,28 @@ command:: 


	# echo 'irq:*' > /sys/kernel/tracing/set_event



The set_event file may also be used to enable events associated to only

a specific module::



	# echo ':mod:<module>' > /sys/kernel/tracing/set_event



Will enable all events in the module ``<module>``.



The text before ``:mod:`` will be parsed to specify specific events that the

module creates::



	# echo '<match>:mod:<module>' > /sys/kernel/tracing/set_event



The above will enable any system or event that ``<match>`` matches. If

``<match>`` is ``"*"`` then it will match all events.



To enable only a specific event within a system::



	# echo '<system>:<event>:mod:<module>' > /sys/kernel/tracing/set_event



If ``<event>`` is ``"*"`` then it will match all events within the system

for a given module.



2.2 Via the 'enable' toggle

---------------------------

kernel/trace/trace.c

+2 −0
Original line number Diff line number Diff line
@@ -5514,6 +5514,8 @@ static const char readme_msg[] = 
	"\t    efield: For event probes ('e' types), the field is on of the fields\n"

	"\t            of the <attached-group>/<attached-event>.\n"

#endif

	"  set_event\t\t- Enables events by name written into it\n"

	"\t\t\t  Can enable module events via: :mod:<module>\n"

	"  events/\t\t- Directory containing all trace event subsystems:\n"

	"      enable\t\t- Write 0/1 to enable/disable tracing of all events\n"

	"  events/<system>/\t- Directory containing all trace events for <system>:\n"

kernel/trace/trace_events.c

+46 −13
Original line number Diff line number Diff line
@@ -1153,17 +1153,36 @@ static void remove_event_file_dir(struct trace_event_file *file) 
 */

static int

__ftrace_set_clr_event_nolock(struct trace_array *tr, const char *match,

			      const char *sub, const char *event, int set)

			      const char *sub, const char *event, int set,

			      const char *mod)

{

	struct trace_event_file *file;

	struct trace_event_call *call;

	char *module __free(kfree) = NULL;

	const char *name;

	int ret = -EINVAL;

	int eret = 0;



	if (mod) {

		char *p;



		module = kstrdup(mod, GFP_KERNEL);

		if (!module)

			return -ENOMEM;



		/* Replace all '-' with '_' as that's what modules do */

		for (p = strchr(module, '-'); p; p = strchr(p + 1, '-'))

			*p = '_';

	}



	list_for_each_entry(file, &tr->events, list) {



		call = file->event_call;



		/* If a module is specified, skip events that are not that module */

		if (module && (!call->module || strcmp(module_name(call->module), module)))

			continue;



		name = trace_event_name(call);



		if (!name || !call->class || !call->class->reg)
@@ -1200,12 +1219,13 @@ __ftrace_set_clr_event_nolock(struct trace_array *tr, const char *match, 
}



static int __ftrace_set_clr_event(struct trace_array *tr, const char *match,

				  const char *sub, const char *event, int set)

				  const char *sub, const char *event, int set,

				  const char *mod)

{

	int ret;



	mutex_lock(&event_mutex);

	ret = __ftrace_set_clr_event_nolock(tr, match, sub, event, set);

	ret = __ftrace_set_clr_event_nolock(tr, match, sub, event, set, mod);

	mutex_unlock(&event_mutex);



	return ret;
@@ -1213,11 +1233,20 @@ static int __ftrace_set_clr_event(struct trace_array *tr, const char *match, 


int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)

{

	char *event = NULL, *sub = NULL, *match;

	char *event = NULL, *sub = NULL, *match, *mod;

	int ret;



	if (!tr)

		return -ENOENT;



	/* Modules events can be appened with :mod:<module> */

	mod = strstr(buf, ":mod:");

	if (mod) {

		*mod = '\0';

		/* move to the module name */

		mod += 5;

	}



	/*

	 * The buf format can be <subsystem>:<event-name>

	 *  *:<event-name> means any event by that name.
@@ -1240,9 +1269,13 @@ int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set) 
			sub = NULL;

		if (!strlen(event) || strcmp(event, "*") == 0)

			event = NULL;

	} else if (mod) {

		/* Allow wildcard for no length or star */

		if (!strlen(match) || strcmp(match, "*") == 0)

			match = NULL;

	}



	ret = __ftrace_set_clr_event(tr, match, sub, event, set);

	ret = __ftrace_set_clr_event(tr, match, sub, event, set, mod);



	/* Put back the colon to allow this to be called again */

	if (buf)
@@ -1270,7 +1303,7 @@ int trace_set_clr_event(const char *system, const char *event, int set) 
	if (!tr)

		return -ENODEV;



	return __ftrace_set_clr_event(tr, NULL, system, event, set);

	return __ftrace_set_clr_event(tr, NULL, system, event, set, NULL);

}

EXPORT_SYMBOL_GPL(trace_set_clr_event);
@@ -1296,7 +1329,7 @@ int trace_array_set_clr_event(struct trace_array *tr, const char *system, 
		return -ENOENT;



	set = (enable == true) ? 1 : 0;

	return __ftrace_set_clr_event(tr, NULL, system, event, set);

	return __ftrace_set_clr_event(tr, NULL, system, event, set, NULL);

}

EXPORT_SYMBOL_GPL(trace_array_set_clr_event);
@@ -1646,7 +1679,7 @@ system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt, 
	if (system)

		name = system->name;



	ret = __ftrace_set_clr_event(dir->tr, NULL, name, NULL, val);

	ret = __ftrace_set_clr_event(dir->tr, NULL, name, NULL, val, NULL);

	if (ret)

		goto out;
@@ -4094,7 +4127,7 @@ int event_trace_del_tracer(struct trace_array *tr) 
	__ftrace_clear_event_pids(tr, TRACE_PIDS | TRACE_NO_PIDS);



	/* Disable any running events */

	__ftrace_set_clr_event_nolock(tr, NULL, NULL, NULL, 0);

	__ftrace_set_clr_event_nolock(tr, NULL, NULL, NULL, 0, NULL);



	/* Make sure no more events are being executed */

	tracepoint_synchronize_unregister();
@@ -4378,7 +4411,7 @@ static __init void event_trace_self_tests(void) 


		pr_info("Testing event system %s: ", system->name);



		ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 1);

		ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 1, NULL);

		if (WARN_ON_ONCE(ret)) {

			pr_warn("error enabling system %s\n",

				system->name);
@@ -4387,7 +4420,7 @@ static __init void event_trace_self_tests(void) 


		event_test_stuff();



		ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 0);

		ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 0, NULL);

		if (WARN_ON_ONCE(ret)) {

			pr_warn("error disabling system %s\n",

				system->name);
@@ -4402,7 +4435,7 @@ static __init void event_trace_self_tests(void) 
	pr_info("Running tests on all trace events:\n");

	pr_info("Testing all events: ");



	ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 1);

	ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 1, NULL);

	if (WARN_ON_ONCE(ret)) {

		pr_warn("error enabling all events\n");

		return;
@@ -4411,7 +4444,7 @@ static __init void event_trace_self_tests(void) 
	event_test_stuff();



	/* reset sysname */

	ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 0);

	ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 0, NULL);

	if (WARN_ON_ONCE(ret)) {

		pr_warn("error disabling all events\n");

		return;