linux-kernel - [BUGFIX PATCH 2/6] perf/probe: Fix to probe a function which has no entry pc

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Date:   Fri, 25 Oct 2019 17:46:34 +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 2/6] perf/probe: Fix to probe a function which has no entry pc

Fix perf probe to probe a function which has no entry pc or
low pc but only has ranges attribute.

probe_point_search_cb() uses dwarf_entrypc() to get the
probe address, but that doesn't work for the function DIE
which has only ranges attribute. Use die_entrypc() instead.

Without this fix,
  # tools/perf/perf probe -k ../build-x86_64/vmlinux -D clear_tasks_mm_cpumask:0
  Probe point 'clear_tasks_mm_cpumask' not found.
    Error: Failed to add events.

With this,
  # tools/perf/perf probe -k ../build-x86_64/vmlinux -D clear_tasks_mm_cpumask:0
  p:probe/clear_tasks_mm_cpumask clear_tasks_mm_cpumask+0

Reported-by: Arnaldo Carvalho de Melo <acme@...nel.org>
Fixes: e1ecbbc3fa83 ("perf probe: Fix to handle optimized not-inlined functions")
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 tools/perf/util/probe-finder.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 2b6513e5725c..71633f55f045 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -982,7 +982,7 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
 		param->retval = find_probe_point_by_line(pf);
 	} else if (die_is_func_instance(sp_die)) {
 		/* Instances always have the entry address */
-		dwarf_entrypc(sp_die, &pf->addr);
+		die_entrypc(sp_die, &pf->addr);
 		/* But in some case the entry address is 0 */
 		if (pf->addr == 0) {
 			pr_debug("%s has no entry PC. Skipped\n",