[PATCH perf/core v2 5/5] perf probe: Allow weak symbols to be probed

From: Masami Hiramatsu
Date: Fri Mar 06 2015 - 02:33:05 EST


From: Namhyung Kim <namhyung@xxxxxxxxxx>

It currently prevents adding probes in weak symbols. But there're cases
that given name is an only weak symbol so that we cannot add probe.

$ perf probe -x /usr/lib/libc.so.6 -a calloc
Failed to find symbol calloc in /usr/lib/libc-2.21.so
Error: Failed to add events.

$ nm /usr/lib/libc.so.6 | grep calloc
000000000007b1f0 t __calloc
000000000007b1f0 T __libc_calloc
000000000007b1f0 W calloc

This change will result in duplicate probes when strong and weak symbols
co-exist in a binary. But I think it's not a big problem since probes
at the weak symbol will never be hit anyway.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
tools/perf/util/probe-event.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index c379ea0..f9c1e53 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -309,10 +309,8 @@ static int find_alternative_probe_point(struct debuginfo *dinfo,

/* Find the address of given function */
map__for_each_symbol_by_name(map, pp->function, sym) {
- if (sym->binding == STB_GLOBAL || sym->binding == STB_LOCAL) {
- address = sym->start;
- break;
- }
+ address = sym->start;
+ break;
}
if (!address) {
ret = -ENOENT;
@@ -2484,8 +2482,7 @@ static int find_probe_functions(struct map *map, char *name)
struct symbol *sym;

map__for_each_symbol_by_name(map, name, sym) {
- if (sym->binding == STB_GLOBAL || sym->binding == STB_LOCAL)
- found++;
+ found++;
}

return found;
@@ -2845,8 +2842,7 @@ static struct strfilter *available_func_filter;
static int filter_available_functions(struct map *map __maybe_unused,
struct symbol *sym)
{
- if ((sym->binding == STB_GLOBAL || sym->binding == STB_LOCAL) &&
- strfilter__compare(available_func_filter, sym->name))
+ if (strfilter__compare(available_func_filter, sym->name))
return 0;
return 1;
}

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