linux-kernel - [PATCH perf/core v7 21/21] perf probe: Support a special SDT probe format

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Message-Id: <20160511135509.23943.4906.stgit@devbox>
Date:	Wed, 11 May 2016 22:55:09 +0900
From:	Masami Hiramatsu <mhiramat@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Masami Hiramatsu <mhiramat@...nel.org>,
	linux-kernel@...r.kernel.org, Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Hemant Kumar <hemant@...ux.vnet.ibm.com>,
	Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
	Brendan Gregg <brendan.d.gregg@...il.com>
Subject: [PATCH perf/core v7 21/21] perf probe: Support a special SDT probe format

Support a special SDT probe format which can omit the '%' prefix
only if the SDT group name starts with "sdt_". So, for example
both of "%sdt_libc:setjump" and "sdt_libc:setjump" are acceptable
for perf probe --add.

Suggested-by: Brendan Gregg <brendan.d.gregg@...il.com>
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 tools/perf/Documentation/perf-probe.txt |    4 +++-
 tools/perf/util/probe-event.c           |   12 ++++++++++--
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index 43523be..2ebde8b 100644
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -152,7 +152,9 @@ Probe points are defined by following syntax.
      [[GROUP:]EVENT=]SRC;PTN [ARG ...]
 
     4) Pre-defined SDT events
-     %[PROVIDER:]SDTEVENT
+     %[sdt_PROVIDER:]SDTEVENT
+     or,
+     sdt_PROVIDER:SDTEVENT
 
 'EVENT' specifies the name of new event, if omitted, it will be set the name of the probed function. You can also specify a group name by 'GROUP', if omitted, set 'probe' is used for kprobe and 'probe_<bin>' is used for uprobe.
 Note that using existing group name can conflict with other events. Especially, using the group name reserved for kernel modules can hide embedded events in the
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index bd31cac..a4819f9 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1245,9 +1245,17 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
 	if (!arg)
 		return -EINVAL;
 
-	if (arg[0] == '%') {
+	/*
+	 * If the probe point starts with '%',
+	 * or starts with "sdt_" and has a ':' but no '=',
+	 * then it should be a SDT/cached probe point.
+	 */
+	if (arg[0] == '%' ||
+	    (!strncmp(arg, "sdt_", 4) &&
+	     !!strchr(arg, ':') && !strchr(arg, '='))) {
 		pev->sdt = true;
-		arg++;
+		if (arg[0] == '%')
+			arg++;
 	}
 
 	ptr = strpbrk(arg, ";=@+%");