linux-kernel - [PATCH 2/5] perf probe: Generate event name with line number

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Date:   Tue,  5 Nov 2019 09:16:59 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org,
        Tom Zanussi <tom.zanussi@...ux.intel.com>,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
        Namhyung Kim <namhyung@...nel.org>
Subject: [PATCH 2/5] perf probe: Generate event name with line number

Generate event name from function name with line number
as <function>_L<line_number>. Note that this is only for
the new event which is defined by function and lines.

If there is another event on same line, you have to use
"-f" option. In that case, the new event has "_1" suffix.

 e.g.
  # perf probe -a kernel_read
  Added new event:
    probe:kernel_read_L0 (on kernel_read)

  You can now use it in all perf tools, such as:

  	perf record -e probe:kernel_read_L0 -aR sleep 1

  # perf probe -a kernel_read:1
  Added new events:
    probe:kernel_read_L1 (on kernel_read:1)

  You can now use it in all perf tools, such as:

  	perf record -e probe:kernel_read_L1_1 -aR sleep 1

  # perf probe -l
    probe:kernel_read_L0 (on kernel_read@...ux/linux/fs/read_write.c)
    probe:kernel_read_L1 (on kernel_read@...ux/linux/fs/read_write.c)

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 tools/perf/util/probe-event.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 91cab5f669d2..d14b970a6461 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1679,6 +1679,14 @@ int parse_perf_probe_command(const char *cmd, struct perf_probe_event *pev)
 	if (ret < 0)
 		goto out;
 
+	/* Generate event name if needed */
+	if (!pev->event && pev->point.function
+			&& !pev->point.lazy_line && !pev->point.offset) {
+		if (asprintf(&pev->event, "%s_L%d", pev->point.function,
+			pev->point.line) < 0)
+			return -ENOMEM;
+	}
+
 	/* Copy arguments and ensure return probe has no C argument */
 	pev->nargs = argc - 1;
 	pev->args = zalloc(sizeof(struct perf_probe_arg) * pev->nargs);