[PATCH 01/10] perf probe: Cut off the gcc optimization postfixes from function name

From: Arnaldo Carvalho de Melo
Date: Tue Jun 16 2015 - 14:24:10 EST


From: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>

Cut off the postfixes which gcc added for optimized routines from the
event name automatically generated from symbol name, since *probe-events
doesn't accept it. Those symbols will be used if we don't use debuginfo
to find target functions.

E.g. without this fix;
-----
# perf probe -va alloc_buf.isra.23
probe-definition(0): alloc_buf.isra.23
symbol:alloc_buf.isra.23 file:(null) line:0 offset:0 return:0 lazy:(null)
[...]
Opening /sys/kernel/debug/tracing/kprobe_events write=1
Added new event:
Writing event: p:probe/alloc_buf.isra.23 _text+4869328
Failed to write event: Invalid argument
Error: Failed to add events. Reason: Invalid argument (Code: -22)
-----
With this fix;
-----
perf probe -va alloc_buf.isra.23
probe-definition(0): alloc_buf.isra.23
symbol:alloc_buf.isra.23 file:(null) line:0 offset:0 return:0 lazy:(null)
[...]
Opening /sys/kernel/debug/tracing/kprobe_events write=1
Added new event:
Writing event: p:probe/alloc_buf _text+4869328
probe:alloc_buf (on alloc_buf.isra.23)

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

perf record -e probe:alloc_buf -aR sleep 1

-----

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Naohiro Aota <naota@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20150612050820.20548.41625.stgit@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/probe-event.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index d4cf50b91839..daa24a249e05 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -2316,6 +2316,7 @@ static int get_new_event_name(char *buf, size_t len, const char *base,
struct strlist *namelist, bool allow_suffix)
{
int i, ret;
+ char *p;

if (*base == '.')
base++;
@@ -2326,6 +2327,10 @@ static int get_new_event_name(char *buf, size_t len, const char *base,
pr_debug("snprintf() failed: %d\n", ret);
return ret;
}
+ /* Cut off the postfixes (e.g. .const, .isra)*/
+ p = strchr(buf, '.');
+ if (p && p != buf)
+ *p = '\0';
if (!strlist__has_entry(namelist, buf))
return 0;

--
2.1.0

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