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

tip:perf/core tip-bot for Arnaldo Carvalho de Melo 1 participant 1 message Nov 22, 2018 perf events

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Commit-ID:  744fafc787deebf26a39e6b5be36026bb2ff65fb
Gitweb:     https://git.kernel.org/tip/744fafc787deebf26a39e6b5be36026bb2ff65fb
Author:     Arnaldo Carvalho de Melo <[email protected]>
AuthorDate: Wed, 7 Nov 2018 10:04:51 -0300
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Wed, 21 Nov 2018 12:00:31 -0300

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 <[email protected]>
Cc David Ahern <[email protected]>
Cc Jiri Olsa <[email protected]>
Cc Namhyung Kim <[email protected]>
Cc Wang Nan <[email protected]>
Link https://lkml.kernel.org/n/[email protected] open here
Signed-off-by Arnaldo Carvalho de Melo <[email protected]>
---
 tools/perf/builtin-trace.c | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)
tools/perf/builtin-trace.c +24 -1
index 8f966c7a7d0d..c423a78b5ecd 100644
@@ -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) {