perf trace: Free syscall->arg_fmt

ASan reports several memory leaks running:

  # perf test "88: Check open filename arg using perf trace + vfs_getname"

The second of these leaks is caused by the arg_fmt field of syscall not
being deallocated.

This patch adds a new function syscall__exit which is called on all
syscalls.table entries in trace__exit, which will free the arg_fmt
field.

Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/d68f25c043d30464ac9fa79c3399e18f429bca82.1626343282.git.rickyman7@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -2266,6 +2266,14 @@ static void *syscall__augmented_args(struct syscall *sc, struct perf_sample *sam
  return augmented_args;
 }
 
+static void syscall__exit(struct syscall *sc)
+{
+ if (!sc)
+ return;
+
+ free(sc->arg_fmt);
+}
+
 static int trace__sys_enter(struct trace *trace, struct evsel *evsel,
  union perf_event *event __maybe_unused,
  struct perf_sample *sample)
@@ -4703,9 +4711,15 @@ static int trace__config(const char *var, const char *value, void *arg)
 
 static void trace__exit(struct trace *trace)
 {
+ int i;
+
  strlist__delete(trace->ev_qualifier);
  free(trace->ev_qualifier_ids.entries);
- free(trace->syscalls.table);
+ if (trace->syscalls.table) {
+ for (i = 0; i <= trace->sctbl->syscalls.max_id; i++)
+ syscall__exit(&trace->syscalls.table[i]);
+ free(trace->syscalls.table);
+ }
  syscalltbl__delete(trace->sctbl);
  zfree(&trace->perfconfig_events);
 }