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From:   Jianlin Lv <iecedge@gmail.com>
To:     corbet@lwn.net, rostedt@goodmis.org, mingo@redhat.com
Cc:     iecedge@gmail.com, jianlv@ebay.com, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org
Subject: [PATCH v2] tracing/kprobes: Add method to display private kprobes in tracefs
Date:   Mon, 25 Jul 2022 06:23:34 +0000
Message-Id: <20220725062334.1778-1-iecedge@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The private kprobes are not added to the global list dyn_event_list,
so there is a missing interface to show probe hit and probe miss.
This patch adds a profiling interface to check the number of hits or
misses for private kprobes.

Signed-off-by: Jianlin Lv <iecedge@gmail.com>
---
v2: update commit message
---
 Documentation/trace/kprobetrace.rst |  6 +++-
 kernel/trace/trace_dynevent.c       | 20 +++++++++++
 kernel/trace/trace_dynevent.h       | 37 ++++++++++++++++++++
 kernel/trace/trace_kprobe.c         | 54 +++++++++++++++++++++++++++++
 4 files changed, 116 insertions(+), 1 deletion(-)

diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst
index b175d88f31eb..8815d64dd8a6 100644
--- a/Documentation/trace/kprobetrace.rst
+++ b/Documentation/trace/kprobetrace.rst
@@ -146,7 +146,11 @@ trigger:
 Event Profiling
 ---------------
 You can check the total number of probe hits and probe miss-hits via
-/sys/kernel/debug/tracing/kprobe_profile.
+/sys/kernel/debug/tracing/kprobe_profile or
+/sys/kernel/debug/tracing/kprobe_local_profile.
+All kprobe events created by kprobe_events will be added to the global
+list, you can get their profiling via kprobe_profile; kprobe_local_profile
+shows profiling for private kprobe events created by perf_kprobe pmu.
 The first column is event name, the second is the number of probe hits,
 the third is the number of probe miss-hits.
 
diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index 076b447a1b88..70ec99cd9c53 100644
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -181,6 +181,26 @@ static const struct seq_operations dyn_event_seq_op = {
 	.show	= dyn_event_seq_show
 };
 
+#ifdef CONFIG_KPROBE_EVENTS
+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);
+}
+#endif /* CONFIG_KPROBE_EVENTS */
+
 /*
  * 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..e30193470295 100644
--- a/kernel/trace/trace_dynevent.h
+++ b/kernel/trace/trace_dynevent.h
@@ -101,6 +101,43 @@ 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);
 
+#ifdef CONFIG_KPROBE_EVENTS
+extern struct list_head local_event_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 *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);
+
+#endif /* CONFIG_KPROBE_EVENTS */
+
 /*
  * 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..76f500b17b46 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1213,6 +1213,52 @@ static const struct file_operations kprobe_profile_ops = {
 	.release        = seq_release,
 };
 
+#ifdef CONFIG_KPROBE_EVENTS
+/* 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,
+};
+#endif /* CONFIG_KPROBE_EVENTS */
+
 /* Kprobe specific fetch functions */
 
 /* Return the length of string -- including null terminal byte */
@@ -1830,6 +1876,7 @@ 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 +1896,7 @@ 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 +1977,12 @@ static __init int init_kprobe_trace(void)
 	trace_create_file("kprobe_profile", TRACE_MODE_READ,
 			  NULL, NULL, &kprobe_profile_ops);
 
+#ifdef CONFIG_KPROBE_EVENTS
+	/* kprobe Local profile */
+	tracefs_create_file("kprobe_local_profile", TRACE_MODE_READ,
+			  NULL, NULL, &kprobe_local_profile_ops);
+#endif /* CONFIG_KPROBE_EVENTS */
+
 	setup_boot_kprobe_events();
 
 	return 0;
-- 
2.25.1