tracing: Auto generate event name when creating a group of events

Currently when creating a specific group of trace events,
take kprobe event as example, the user must use the following format:
p:GRP/EVENT [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS],
which means user must enter EVENT name, one example is:

  echo 'p:usb_gadget/config_usb_cfg_link config_usb_cfg_link $arg1' >> kprobe_events

It is not simple if there are too many entries because the event name is
the same as symbol name.

This change allows user to specify no EVENT name, format changed as:

   p:GRP/ [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]

It will generate event name automatically and one example is:

  echo 'p:usb_gadget/ config_usb_cfg_link $arg1' >> kprobe_events.

Link: https://lore.kernel.org/all/1656296348-16111-4-git-send-email-quic_linyyuan@quicinc.com/

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 13 insertions, 12 deletions

diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
index 8979cb9ec37a..a30f21499e81 100644
--- a/kernel/trace/trace_eprobe.c
+++ b/kernel/trace/trace_eprobe.c
@@ -125,6 +125,7 @@ static bool eprobe_dyn_event_match(const char *system, const char *event,
 	 * We match the following:
 	 *  event only			- match all eprobes with event name
 	 *  system and event only	- match all system/event probes
+	 *  system only			- match all system probes
 	 *
 	 * The below has the above satisfied with more arguments:
 	 *
@@ -143,7 +144,7 @@ static bool eprobe_dyn_event_match(const char *system, const char *event,
 		return false;
 
 	/* Must match the event name */
-	if (strcmp(trace_probe_name(&ep->tp), event) != 0)
+	if (event[0] != '\0' && strcmp(trace_probe_name(&ep->tp), event) != 0)
 		return false;
 
 	/* No arguments match all */
@@ -848,7 +849,7 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 {
 	/*
 	 * Argument syntax:
-	 *      e[:[GRP/]ENAME] SYSTEM.EVENT [FETCHARGS]
+	 *      e[:[GRP/][ENAME]] SYSTEM.EVENT [FETCHARGS]
 	 * Fetch args:
 	 *  <name>=$<field>[:TYPE]
 	 */
@@ -858,6 +859,7 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 	struct trace_eprobe *ep = NULL;
 	char buf1[MAX_EVENT_NAME_LEN];
 	char buf2[MAX_EVENT_NAME_LEN];
+	char gbuf[MAX_EVENT_NAME_LEN];
 	int ret = 0;
 	int i;
 
@@ -869,25 +871,24 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 	event = strchr(&argv[0][1], ':');
 	if (event) {
 		event++;
-		ret = traceprobe_parse_event_name(&event, &group, buf1,
+		ret = traceprobe_parse_event_name(&event, &group, gbuf,
 						  event - argv[0]);
 		if (ret)
 			goto parse_error;
-	} else {
-		strscpy(buf1, argv[1], MAX_EVENT_NAME_LEN);
-		sanitize_event_name(buf1);
-		event = buf1;
 	}
-	if (!is_good_name(event) || !is_good_name(group))
-		goto parse_error;
 
 	trace_probe_log_set_index(1);
 	sys_event = argv[1];
-	ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2,
-					  sys_event - argv[1]);
-	if (ret || !sys_name)
+	ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2, 0);
+	if (!sys_event || !sys_name)
 		goto parse_error;
 
+	if (!event) {
+		strscpy(buf1, argv[1], MAX_EVENT_NAME_LEN);
+		sanitize_event_name(buf1);
+		event = buf1;
+	}
+
 	mutex_lock(&event_mutex);
 	event_call = find_and_get_event(sys_name, sys_event);
 	ep = alloc_event_probe(group, event, event_call, argc - 2);