linux-kernel - [PATCH v3 3/7] perf probe: Do not show non representive lines by perf-probe -L

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Date:   Mon, 18 Nov 2019 17:12:10 +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 v3 3/7] perf probe: Do not show non representive lines by perf-probe -L

Since perf probe -L shows non representive lines, it can be
mislead users where user can put probes.
This prevents to show such non representive lines so that user
can understand which lines user can probe.

  # perf probe -L kernel_read
  <kernel_read@...ild/linux-pvZVvI/linux-5.0.0/fs/read_write.c:0>
        0  ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
           {
        2         mm_segment_t old_fs;
                  ssize_t result;

                  old_fs = get_fs();
        6         set_fs(get_ds());
                  /* The cast to a user pointer is valid due to the set_fs() */
        8         result = vfs_read(file, (void __user *)buf, count, pos);
        9         set_fs(old_fs);
       10         return result;
           }
           EXPORT_SYMBOL(kernel_read);

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 tools/perf/util/probe-finder.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index ef1b320cedf8..f12ad507a822 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1734,12 +1734,19 @@ static int line_range_walk_cb(const char *fname, int lineno,
 			      void *data)
 {
 	struct line_finder *lf = data;
+	const char *__fname;
+	int __lineno;
 	int err;
 
 	if ((strtailcmp(fname, lf->fname) != 0) ||
 	    (lf->lno_s > lineno || lf->lno_e < lineno))
 		return 0;
 
+	/* Make sure this line can be reversable */
+	if (cu_find_lineinfo(&lf->cu_die, addr, &__fname, &__lineno) > 0
+	    && (lineno != __lineno || strcmp(fname, __fname)))
+		return 0;
+
 	err = line_range_add_line(fname, lineno, lf->lr);
 	if (err < 0 && err != -EEXIST)
 		return err;