linux-kernel - [tip: perf/core] perf probe: Skip overlapped location on searching variables

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Message-ID: <157355747242.29376.1305190875966623515.tip-bot2@tip-bot2>
Date:   Tue, 12 Nov 2019 11:17:52 -0000
From:   "tip-bot2 for Masami Hiramatsu" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        linux-kernel@...r.kernel.org
Subject: [tip: perf/core] perf probe: Skip overlapped location on searching variables

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     dee36a2abb67c175265d49b9a8c7dfa564463d9a
Gitweb:        https://git.kernel.org/tip/dee36a2abb67c175265d49b9a8c7dfa564463d9a
Author:        Masami Hiramatsu <mhiramat@...nel.org>
AuthorDate:    Wed, 30 Oct 2019 16:09:49 +09:00
Committer:     Arnaldo Carvalho de Melo <acme@...hat.com>
CommitterDate: Thu, 07 Nov 2019 08:30:19 -03:00

perf probe: Skip overlapped location on searching variables

Since debuginfo__find_probes() callback function can be called with  the
location which already passed, the callback function must filter out
such overlapped locations.

add_probe_trace_event() has already done it by commit 1a375ae7659a
("perf probe: Skip same probe address for a given line"), but
add_available_vars() doesn't. Thus perf probe -v shows same address
repeatedly as below:

  # perf probe -V vfs_read:18
  Available variables at vfs_read:18
          @<vfs_read+217>
                  char*   buf
                  loff_t* pos
                  ssize_t ret
                  struct file*    file
          @<vfs_read+217>
                  char*   buf
                  loff_t* pos
                  ssize_t ret
                  struct file*    file
          @<vfs_read+226>
                  char*   buf
                  loff_t* pos
                  ssize_t ret
                  struct file*    file

With this fix, perf probe -V shows it correctly:

  # perf probe -V vfs_read:18
  Available variables at vfs_read:18
          @<vfs_read+217>
                  char*   buf
                  loff_t* pos
                  ssize_t ret
                  struct file*    file
          @<vfs_read+226>
                  char*   buf
                  loff_t* pos
                  ssize_t ret
                  struct file*    file

Fixes: cf6eb489e5c0 ("perf probe: Show accessible local variables")
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Link: http://lore.kernel.org/lkml/157241938927.32002.4026859017790562751.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/probe-finder.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 582f8c3..9ecea45 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1428,6 +1428,18 @@ error:
 	return DIE_FIND_CB_END;
 }
 
+static bool available_var_finder_overlap(struct available_var_finder *af)
+{
+	int i;
+
+	for (i = 0; i < af->nvls; i++) {
+		if (af->pf.addr == af->vls[i].point.address)
+			return true;
+	}
+	return false;
+
+}
+
 /* Add a found vars into available variables list */
 static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
 {
@@ -1438,6 +1450,14 @@ static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
 	Dwarf_Die die_mem;
 	int ret;
 
+	/*
+	 * 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 (available_var_finder_overlap(af))
+		return 0;
+
 	/* Check number of tevs */
 	if (af->nvls == af->max_vls) {
 		pr_warning("Too many( > %d) probe point found.\n", af->max_vls);