linux-kernel - [BUGFIX PATCH V2 4/6] perf/probe: Fix to list probe event with correct line number

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Date:   Sat, 26 Oct 2019 18:00:55 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [BUGFIX PATCH V2 4/6] perf/probe: Fix to list probe event with correct line number

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 --force -a clear_tasks_mm_cpumask:0 clear_tasks_mm_cpumask:21
  Added new events:
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask)
    probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:21)

  You can now use it in all perf tools, such as:

	perf record -e probe:clear_tasks_mm_cpumask_1 -aR sleep 1

  # perf probe -l
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask+18446744071579478000@...ux-5.0.0/kernel/cpu.c)
    probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask+18446744071579478067@...ux-5.0.0/kernel/cpu.c)

With this,
  # perf probe -l
    probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask@...ux-5.0.0/kernel/cpu.c)
    probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:21@...ux-5.0.0/kernel/cpu.c)

Fixes: 1d46ea2a6a40 ("perf probe: Fix listing incorrect line number with inline function")
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 tools/perf/util/probe-finder.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 2fa932bcf960..88e17a4f5ac3 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1566,7 +1566,7 @@ int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
 		/* 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;
@@ -1583,7 +1583,7 @@ int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
 		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.