linux-kernel - [PATCH] perf/probe: Skip same probe address

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Date:   Thu, 19 Sep 2019 12:41:10 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Wang Nan <wangnan0@...wei.com>, Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] perf/probe: Skip same probe address

Fix to skip making a same probe address on given line.

Since dwarf line info contains several entries for one line
with different column, perf probe will make a different
probe on same address if user specifies a probe point by
"function:line" or "file:line".

e.g.
 $ perf probe -D kernel_read:8
 p:probe/kernel_read_L8 kernel_read+39
 p:probe/kernel_read_L8_1 kernel_read+39

This skips such duplicated probe address.

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 tools/perf/util/probe-finder.c |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 025fc4491993..02ca95deaf2c 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1244,6 +1244,17 @@ static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
 	return n;
 }
 
+static bool trace_event_finder_overlap(struct trace_event_finder *tf)
+{
+	int i;
+
+	for (i = 0; i < tf->ntevs; i++) {
+		if (tf->pf.addr == tf->tevs[i].point.address)
+			return true;
+	}
+	return false;
+}
+
 /* Add a found probe point into trace event list */
 static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
 {
@@ -1254,6 +1265,14 @@ static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
 	struct perf_probe_arg *args = NULL;
 	int ret, i;
 
+	/*
+	 * For some reason (e.g. different column assigned to same address)
+	 * This callback can be called with the address which already passed.
+	 * Ignore it first.
+	 */
+	if (trace_event_finder_overlap(tf))
+		return 0;
+
 	/* Check number of tevs */
 	if (tf->ntevs == tf->max_tevs) {
 		pr_warning("Too many( > %d) probe point found.\n",