[PATCH] tracing/kprobe: Add tracefs to show private kprobe

[PATCH] tracing/kprobe: Add tracefs to show private kprobe

[Jianlin Lv]

List private kprobe event to new created local_event_list;
Add tracefs file kprobe_local_profile to show events which
in local_event_list.

Signed-off-by: Jianlin Lv <iecedge@gmail.com>
---
 kernel/trace/trace_dynevent.c | 18 +++++++++++++
 kernel/trace/trace_dynevent.h | 33 +++++++++++++++++++++++
 kernel/trace/trace_kprobe.c   | 50 +++++++++++++++++++++++++++++++++++
 3 files changed, 101 insertions(+)

diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index 076b447a1b88..8411104ad6d8 100644
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -181,6 +181,24 @@ static const struct seq_operations dyn_event_seq_op = {
 	.show	= dyn_event_seq_show
 };
 
+LIST_HEAD(local_event_list);
+
+void *local_event_seq_start(struct seq_file *m, loff_t *pos)
+{
+	mutex_lock(&event_mutex);
+	return seq_list_start(&local_event_list, *pos);
+}
+
+void *local_event_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &local_event_list, pos);
+}
+
+void local_event_seq_stop(struct seq_file *m, void *v)
+{
+	mutex_unlock(&event_mutex);
+}
+
 /*
  * dyn_events_release_all - Release all specific events
  * @type:	the dyn_event_operations * which filters releasing events
diff --git a/kernel/trace/trace_dynevent.h b/kernel/trace/trace_dynevent.h
index 936477a111d3..e6413969f9ed 100644
--- a/kernel/trace/trace_dynevent.h
+++ b/kernel/trace/trace_dynevent.h
@@ -64,6 +64,7 @@ struct dyn_event {
 };
 
 extern struct list_head dyn_event_list;
+extern struct list_head local_event_list;
 
 static inline
 int dyn_event_init(struct dyn_event *ev, struct dyn_event_operations *ops)
@@ -95,12 +96,44 @@ static inline void dyn_event_remove(struct dyn_event *ev)
 	list_del_init(&ev->list);
 }
 
+static inline
+int local_event_init(struct dyn_event *ev, struct dyn_event_operations *ops)
+{
+	if (!ev || !ops)
+		return -EINVAL;
+
+	INIT_LIST_HEAD(&ev->list);
+	ev->ops = ops;
+	return 0;
+}
+
+static inline int local_event_add(struct dyn_event *ev)
+{
+	lockdep_assert_held(&event_mutex);
+
+	if (!ev || !ev->ops)
+		return -EINVAL;
+
+	list_add_tail(&ev->list, &local_event_list);
+	return 0;
+}
+
+static inline void local_event_remove(struct dyn_event *ev)
+{
+	lockdep_assert_held(&event_mutex);
+	list_del_init(&ev->list);
+}
+
 void *dyn_event_seq_start(struct seq_file *m, loff_t *pos);
 void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos);
 void dyn_event_seq_stop(struct seq_file *m, void *v);
 int dyn_events_release_all(struct dyn_event_operations *type);
 int dyn_event_release(const char *raw_command, struct dyn_event_operations *type);
 
+void *local_event_seq_start(struct seq_file *m, loff_t *pos);
+void *local_event_seq_next(struct seq_file *m, void *v, loff_t *pos);
+void local_event_seq_stop(struct seq_file *m, void *v);
+
 /*
  * for_each_dyn_event	-	iterate over the dyn_event list
  * @pos:	the struct dyn_event * to use as a loop cursor
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index a245ea673715..8fd39033d2ba 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1213,6 +1213,50 @@ static const struct file_operations kprobe_profile_ops = {
 	.release        = seq_release,
 };
 
+/* kprobe Local profile  */
+static int local_probes_profile_seq_show(struct seq_file *m, void *v)
+{
+	struct dyn_event *ev = v;
+	struct trace_kprobe *tk;
+
+	if (!is_trace_kprobe(ev))
+		return 0;
+
+	tk = to_trace_kprobe(ev);
+	seq_printf(m, "  %-44s %15lu %15lu\n",
+		trace_probe_name(&tk->tp),
+		trace_kprobe_nhit(tk),
+		tk->rp.kp.nmissed);
+
+	return 0;
+}
+
+static const struct seq_operations local_profile_seq_op = {
+	.start  = local_event_seq_start,
+	.next   = local_event_seq_next,
+	.stop   = local_event_seq_stop,
+	.show   = local_probes_profile_seq_show
+};
+
+static int local_profile_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	ret = security_locked_down(LOCKDOWN_TRACEFS);
+	if (ret)
+		return ret;
+
+	return seq_open(file, &local_profile_seq_op);
+}
+
+static const struct file_operations kprobe_local_profile_ops = {
+	.owner          = THIS_MODULE,
+	.open           = local_profile_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = seq_release,
+};
+
 /* Kprobe specific fetch functions */
 
 /* Return the length of string -- including null terminal byte */
@@ -1830,6 +1874,7 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
 	if (ret < 0)
 		goto error;
 
+	local_event_add(&tk->devent);
 	return trace_probe_event_call(&tk->tp);
 error:
 	free_trace_kprobe(tk);
@@ -1849,6 +1894,7 @@ void destroy_local_trace_kprobe(struct trace_event_call *event_call)
 		return;
 	}
 
+	local_event_remove(&tk->devent);
 	__unregister_trace_kprobe(tk);
 
 	free_trace_kprobe(tk);
@@ -1929,6 +1975,10 @@ static __init int init_kprobe_trace(void)
 	trace_create_file("kprobe_profile", TRACE_MODE_READ,
 			  NULL, NULL, &kprobe_profile_ops);
 
+	/* kprobe Local profile */
+	tracefs_create_file("kprobe_local_profile", TRACE_MODE_READ,
+			  NULL, NULL, &kprobe_local_profile_ops);
+
 	setup_boot_kprobe_events();
 
 	return 0;
-- 
2.25.1

Re: [PATCH] tracing/kprobe: Add tracefs to show private kprobe

[Steven Rostedt]

On Sun, 24 Jul 2022 09:10:50 +0000
Jianlin Lv <iecedge@gmail.com> wrote:

> List private kprobe event to new created local_event_list;
> Add tracefs file kprobe_local_profile to show events which
> in local_event_list.

This states what you are doing, but not why you are doing it.

The subject of a commit should be the what, and the body should explain
the why.

And the subject is confusing because you are not "adding tracefs", it
should state:

   tracing/kprobes: Add method to display private kprobes in tracefs

Or something like that.

-- Steve