[Dle-develop] [PATCH -tip v14 12/12] tracing: Add kprobes event profiling interface

[Masami H. <mhi...@re...>]

Add profiling interaces for each kprobes event. This interface provides
how many times each probe hit or missed.

Signed-off-by: Masami Hiramatsu <mhi...@re...>
Cc: Ananth N Mavinakayanahalli <an...@in...>
Cc: Avi Kivity <av...@re...>
Cc: Andi Kleen <ak...@li...>
Cc: Christoph Hellwig <hc...@in...>
Cc: Frank Ch. Eigler <fc...@re...>
Cc: Frederic Weisbecker <fwe...@gm...>
Cc: H. Peter Anvin <hp...@zy...>
Cc: Ingo Molnar <mi...@el...>
Cc: Jason Baron <jb...@re...>
Cc: Jim Keniston <jke...@us...>
Cc: K.Prasad <pr...@li...>
Cc: Lai Jiangshan <la...@cn...>
Cc: Li Zefan <li...@cn...>
Cc: Przemysław Pawełczyk <prz...@pa...>
Cc: Roland McGrath <ro...@re...>
Cc: Sam Ravnborg <sa...@ra...>
Cc: Srikar Dronamraju <sr...@li...>
Cc: Steven Rostedt <ro...@go...>
Cc: Tom Zanussi <tza...@gm...>
Cc: Vegard Nossum <veg...@gm...>
---

 Documentation/trace/kprobetrace.txt |    8 +++++++
 kernel/trace/trace_kprobe.c         |   43 +++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 0 deletions(-)

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 5e59e85..3de7517 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -70,6 +70,14 @@ filter:
  names and field names for describing filters.
 
 
+Event Profiling
+---------------
+ You can check the total number of probe hits and probe miss-hits via
+/sys/kernel/debug/tracing/kprobe_profile.
+ The first column is event name, the second is the number of probe hits,
+the third is the number of probe miss-hits.
+
+
 Usage examples
 --------------
 To add a probe as a new event, write a new definition to kprobe_events
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 0e8498e..0f5d0a6 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -184,6 +184,7 @@ struct trace_probe {
 		struct kprobe		kp;
 		struct kretprobe	rp;
 	};
+	unsigned long 		nhit;
 	const char		*symbol;	/* symbol name */
 	struct ftrace_event_call	call;
 	struct trace_event		event;
@@ -781,6 +782,37 @@ static const struct file_operations kprobe_events_ops = {
 	.write		= probes_write,
 };
 
+/* Probes profiling interfaces */
+static int probes_profile_seq_show(struct seq_file *m, void *v)
+{
+	struct trace_probe *tp = v;
+
+	seq_printf(m, "  %-44s %15lu %15lu\n", tp->call.name, tp->nhit,
+		   probe_is_return(tp) ? tp->rp.kp.nmissed : tp->kp.nmissed);
+
+	return 0;
+}
+
+static const struct seq_operations profile_seq_op = {
+	.start  = probes_seq_start,
+	.next   = probes_seq_next,
+	.stop   = probes_seq_stop,
+	.show   = probes_profile_seq_show
+};
+
+static int profile_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &profile_seq_op);
+}
+
+static const struct file_operations kprobe_profile_ops = {
+	.owner          = THIS_MODULE,
+	.open           = profile_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = seq_release,
+};
+
 /* Kprobe handler */
 static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
 {
@@ -791,6 +823,8 @@ static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
 	unsigned long irq_flags;
 	struct ftrace_event_call *call = &tp->call;
 
+	tp->nhit++;
+
 	local_save_flags(irq_flags);
 	pc = preempt_count();
 
@@ -1143,9 +1177,18 @@ static __init int init_kprobe_trace(void)
 	entry = debugfs_create_file("kprobe_events", 0644, d_tracer,
 				    NULL, &kprobe_events_ops);
 
+	/* Event list interface */
 	if (!entry)
 		pr_warning("Could not create debugfs "
 			   "'kprobe_events' entry\n");
+
+	/* Profile interface */
+	entry = debugfs_create_file("kprobe_profile", 0444, d_tracer,
+				    NULL, &kprobe_profile_ops);
+
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'kprobe_profile' entry\n");
 	return 0;
 }
 fs_initcall(init_kprobe_trace);


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhi...@re...