linux-kernel - [PATCH 3.16 068/148] perf probe: Fix to list probe event with correct line number

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Message-ID: <lsq.1581185940.311293614@decadent.org.uk>
Date:   Sat, 08 Feb 2020 18:20:07 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Namhyung Kim" <namhyung@...nel.org>,
        "Masami Hiramatsu" <mhiramat@...nel.org>,
        "Arnaldo Carvalho de Melo" <acme@...hat.com>,
        "Jiri Olsa" <jolsa@...hat.com>
Subject: [PATCH 3.16 068/148] perf probe: Fix to list probe event with
 correct line number

3.16.82-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Masami Hiramatsu <mhiramat@...nel.org>

commit 3895534dd78f0fd4d3f9e05ee52b9cdd444a743e upstream.

Since debuginfo__find_probe_point() uses dwarf_entrypc() for finding the
entry address of the function on which a probe is, it will fail when the
function DIE has only ranges attribute.

To fix this issue, use die_entrypc() instead of dwarf_entrypc().

Without this fix, perf probe -l shows incorrect offset:

  # perf probe -l
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask+18446744071579263632@...k/linux/linux/kernel/cpu.c)
    probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask+18446744071579263752@...k/linux/linux/kernel/cpu.c)

With this:

  # perf probe -l
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask@...k/linux/linux/kernel/cpu.c)
    probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:21@...k/linux/linux/kernel/cpu.c)

Committer testing:

Before:

  [root@...co ~]# perf probe -l
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask+18446744071579765152@...nel/cpu.c)
  [root@...co ~]#

After:

  [root@...co ~]# perf probe -l
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask@...nel/cpu.c)
  [root@...co ~]#

Fixes: 1d46ea2a6a40 ("perf probe: Fix listing incorrect line number with inline function")
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/157199321227.8075.14655572419136993015.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 tools/perf/util/probe-finder.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1345,7 +1345,7 @@ int debuginfo__find_probe_point(struct d
 		/* Get function entry information */
 		func = basefunc = dwarf_diename(&spdie);
 		if (!func ||
-		    dwarf_entrypc(&spdie, &baseaddr) != 0 ||
+		    die_entrypc(&spdie, &baseaddr) != 0 ||
 		    dwarf_decl_line(&spdie, &baseline) != 0) {
 			lineno = 0;
 			goto post;
@@ -1362,7 +1362,7 @@ int debuginfo__find_probe_point(struct d
 		while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
 						&indie)) {
 			/* There is an inline function */
-			if (dwarf_entrypc(&indie, &_addr) == 0 &&
+			if (die_entrypc(&indie, &_addr) == 0 &&
 			    _addr == addr) {
 				/*
 				 * addr is at an inline function entry.