perf trace: See if there is a map named "filtered_pids"

Lookup for the first map named "filtered_pids" and, if augmenting
syscalls, i.e. if a BPF event is present and the
"__augmented_syscalls__" is present, then fill in that map with the pids
to filter, be it feedback loop ones (perf trace's pid, its father if it
is "sshd", more auto-filtered in the future) or the ones explicitely
stated in the tool command line via --filter-pids.

The code to actually fill in the map comes next.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-rhzytmw7qpe6lqyjxi1ded9t@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 8f966c7..c423a78 100644 (file)
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -18,6 +18,7 @@
 
 #include <traceevent/event-parse.h>
 #include <api/fs/tracing_path.h>
+#include <bpf/bpf.h>
 #include "builtin.h"
 #include "util/cgroup.h"
 #include "util/color.h"
@@ -99,6 +100,7 @@ struct trace {
        struct {
                size_t          nr;
                pid_t           *entries;
+               struct bpf_map  *map;
        }                       filter_pids;
        double                  duration_filter;
        double                  runtime_ms;
@@ -3315,6 +3317,25 @@ static int trace__parse_cgroups(const struct option *opt, const char *str, int u
        return 0;
 }
 
+static struct bpf_map *bpf__find_map_by_name(const char *name)
+{
+       struct bpf_object *obj, *tmp;
+
+       bpf_object__for_each_safe(obj, tmp) {
+               struct bpf_map *map = bpf_object__find_map_by_name(obj, name);
+               if (map)
+                       return map;
+
+       }
+
+       return NULL;
+}
+
+static void trace__set_bpf_map_filtered_pids(struct trace *trace)
+{
+       trace->filter_pids.map = bpf__find_map_by_name("pids_filtered");
+}
+
 int cmd_trace(int argc, const char **argv)
 {
        const char *trace_usage[] = {
@@ -3451,8 +3472,10 @@ int cmd_trace(int argc, const char **argv)
                goto out;
        }
 
-       if (evsel)
+       if (evsel) {
                trace.syscalls.events.augmented = evsel;
+               trace__set_bpf_map_filtered_pids(&trace);
+       }
 
        err = bpf__setup_stdout(trace.evlist);
        if (err) {