[PATCH 3/5] perf probe: Set retprobe flag when probe in address-based alternative mode

From: Arnaldo Carvalho de Melo
Date: Mon Apr 13 2015 - 18:16:38 EST

From: He Kuang <hekuang@xxxxxxxxxx>

When perf probe searched in a debuginfo file and failed, it tried with
an alternative, in function get_alternative_probe_event():

memcpy(tmp, &pev->point, sizeof(*tmp));
memset(&pev->point, 0, sizeof(pev->point));

In this case, it drops the retprobe flag and forgets to set it back in
find_alternative_probe_point(), so the problem occurs.

Can be reproduced as following:

$ perf probe -v -k vmlinux --add='sys_write%return'
Added new event:
Writing event: p:probe/sys_write _stext+1584952
probe:sys_write (on sys_write%return)

$ cat /sys/kernel/debug/tracing/kprobe_events
p:probe/sys_write _stext+1584952

After this patch:

$ perf probe -v -k vmlinux --add='sys_write%return'
Added new event:
Writing event: r:probe/sys_write SyS_write+0
probe:sys_write (on sys_write%return)

$ cat /sys/kernel/debug/tracing/kprobe_events
r:probe/sys_write SyS_write

Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1428925290-5623-1-git-send-email-hekuang@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
tools/perf/util/probe-event.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 30545ce2c712..5483d98236d3 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -332,6 +332,7 @@ static int find_alternative_probe_point(struct debuginfo *dinfo,
else {
result->offset += pp->offset;
result->line += pp->line;
+ result->retprobe = pp->retprobe;
ret = 0;


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