tracing: Add enabling of events to boot instances

Add the format of:

  trace_instance=foo,sched:sched_switch,irq_handler_entry,initcall

That will create the "foo" instance and enable the sched_switch event
(here were the "sched" system is explicitly specified), the
irq_handler_entry event, and all events under the system initcall.

Link: https://lkml.kernel.org/r/20230207173026.386114535@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ross Zwisler <zwisler@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 4 insertions, 5 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index b07931ad97de..cf3fd74fa675 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -3750,10 +3750,9 @@ static __init int event_trace_memsetup(void)
 	return 0;
 }
 
-static __init void
-early_enable_events(struct trace_array *tr, bool disable_first)
+__init void
+early_enable_events(struct trace_array *tr, char *buf, bool disable_first)
 {
-	char *buf = bootup_event_buf;
 	char *token;
 	int ret;
 
@@ -3806,7 +3805,7 @@ static __init int event_trace_enable(void)
 	 */
 	__trace_early_add_events(tr);
 
-	early_enable_events(tr, false);
+	early_enable_events(tr, bootup_event_buf, false);
 
 	trace_printk_start_comm();
 
@@ -3834,7 +3833,7 @@ static __init int event_trace_enable_again(void)
 	if (!tr)
 		return -ENODEV;
 
-	early_enable_events(tr, true);
+	early_enable_events(tr, bootup_event_buf, true);
 
 	return 0;
 }