linux-kernel - [RFC PATCH 3/8] perf probe: Improve detection of file/function name in the probe pattern

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Message-Id: <de6c0cd8236de1cabc179e456514c2a399cbc7b5.1418146300.git.naveen.n.rao@linux.vnet.ibm.com>
Date:	Tue,  9 Dec 2014 23:04:01 +0530
From:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	acme@...nel.org, mpe@...erman.id.au
Cc:	ananth@...ibm.com
Subject: [RFC PATCH 3/8] perf probe: Improve detection of file/function name in the probe pattern

Currently, perf probe considers patterns including a '.' to be a file.
However, this causes problems on powerpc ABIv1 where all functions have
a leading '.':

  $ perf probe -F | grep schedule_timeout_interruptible
  .schedule_timeout_interruptible
  $ perf probe .schedule_timeout_interruptible
  Semantic error :File always requires line number or lazy pattern.
    Error: Command Parse Error.

Fix this by checking the probe pattern in more detail.

Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
---
 tools/perf/util/probe-event.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index c150ca4..c7e01ef 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -999,6 +999,24 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
 		arg = tmp;
 	}
 
+	/*
+	 * Check arg is function or file name and copy it.
+	 *
+	 * We consider arg to be a file spec if and only if it satisfies
+	 * all of the below criteria::
+	 * - it does not include any of "+@%",
+	 * - it includes one of ":;", and
+	 * - it has a period '.' in the name.
+	 *
+	 * Otherwise, we consider arg to be a function specification.
+	 */
+	c = 0;
+	if (!strpbrk(arg, "+@%") && (ptr = strpbrk(arg, ";:")) != NULL) {
+		/* This is a file spec if it includes a '.' before ; or : */
+		if (memchr(arg, '.', ptr-arg))
+			c = 1;
+	}
+
 	ptr = strpbrk(arg, ";:+@%");
 	if (ptr) {
 		nc = *ptr;
@@ -1009,10 +1027,9 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
 	if (tmp == NULL)
 		return -ENOMEM;
 
-	/* Check arg is function or file and copy it */
-	if (strchr(tmp, '.'))	/* File */
+	if (c == 1)
 		pp->file = tmp;
-	else			/* Function */
+	else
 		pp->function = tmp;
 
 	/* Parse other options */
-- 
2.1.3

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