[PATCH 23/27] perf probe: Ignore the error of finding inline instance

From: Arnaldo Carvalho de Melo
Date: Thu Sep 29 2016 - 10:38:26 EST


From: Masami Hiramatsu <mhiramat@xxxxxxxxxx>

Ignore the error when the perf probe failed to find inline function
instances. This can happen when we search a method in C++ debuginfo. If
there is completely no instance in target, perf probe can return an
error.

E.g. without this fix:
----
$ perf probe -x /usr/lib64/libstdc++.so.6 -vD showmanyc
probe-definition(0): showmanyc
symbol:showmanyc file:(null) line:0 offset:0 return:0 lazy:(null)
0 arguments
symbol:catch file:(null) line:0 offset:0 return:0 lazy:(null)
symbol:throw file:(null) line:0 offset:0 return:0 lazy:(null)
symbol:rethrow file:(null) line:0 offset:0 return:0 lazy:(null)
Open Debuginfo file: /usr/lib/debug/usr/lib64/libstdc++.so.6.0.22.debug
Try to find probe point from debuginfo.
Matched function: showmanyc
An error occurred in debuginfo analysis (-2).
Trying to use symbols.
Failed to find symbol showmanyc in /usr/lib64/libstdc++.so.6.0.22
Error: Failed to add events. Reason: No such file or directory (Code: -2)
----

This is because one of showmanyc is defined as inline but no instance
found. With this fix, it is succeeded to show as below.
----
$ perf probe -x /usr/lib64/libstdc++.so.6 -D showmanyc
p:probe_libstdc++/showmanyc /usr/lib64/libstdc++.so.6.0.22:0xb0e50
p:probe_libstdc++/showmanyc_1 /usr/lib64/libstdc++.so.6.0.22:0xc7c40
p:probe_libstdc++/showmanyc_2 /usr/lib64/libstdc++.so.6.0.22:0xecfa0
p:probe_libstdc++/showmanyc_3 /usr/lib64/libstdc++.so.6.0.22:0x115fc0
p:probe_libstdc++/showmanyc_4 /usr/lib64/libstdc++.so.6.0.22:0x121a90
----

Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Tested-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/147464489775.29804.3190419491209875936.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/probe-finder.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 8daca4fc1f8d..5fe8325e81f2 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -988,7 +988,8 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
if (pp->file && strtailcmp(pp->file, dwarf_decl_file(sp_die)))
return DWARF_CB_OK;

- pr_debug("Matched function: %s\n", dwarf_diename(sp_die));
+ pr_debug("Matched function: %s [%lx]\n", dwarf_diename(sp_die),
+ (unsigned long)dwarf_dieoffset(sp_die));
pf->fname = dwarf_decl_file(sp_die);
if (pp->line) { /* Function relative line */
dwarf_decl_line(sp_die, &pf->lno);
@@ -1011,7 +1012,7 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
param->retval = die_walk_instances(sp_die,
probe_point_inline_cb, (void *)pf);
/* This could be a non-existed inline definition */
- if (param->retval == -ENOENT && strisglob(pp->function))
+ if (param->retval == -ENOENT)
param->retval = 0;
}

--
2.7.4