[PATCH] perf tools: Allow BPF placeholder dummy events to collect --filter options

[Wang Nan <wangnan0@huawei.com>]

This patch improves collection and setting of filters, allows --filter
be set to BPF placeholder events (which is a software dummy event).

perf_evsel__is_dummy(), perf_evsel__is_bpf_placeholder() and
perf_evsel__can_filter() are introduced for this.

Test result:

 # perf record --event dummy --exclude-perf
 --exclude-perf option should follow a -e tracepoint option

 # perf record --event dummy:u --exclude-perf ls
 --exclude-perf option should follow a -e tracepoint option

 # perf record --event test.o --exclude-perf ls
 Added new event:
   perf_bpf_probe:func_vfs_write (on vfs_write)
 ...

 # perf record --event dummy.o --exclude-perf ls
 Added new event:
   perf_bpf_probe:func_write (on sys_write)
 ...

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/evlist.c       |  7 +++++++
 tools/perf/util/evsel.c        | 32 ++++++++++++++++++++++++++++++++
 tools/perf/util/evsel.h        | 23 +++++++++++++++++++++++
 tools/perf/util/parse-events.c |  4 ++--
 4 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 93db4c1..29212dc 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1223,6 +1223,13 @@ int perf_evlist__apply_filters(struct perf_evlist *evlist, struct perf_evsel **e
 			continue;
 
 		/*
+		 * Filters are allowed to be set to dummy event for BPF object
+		 * placeholder. Don't really apply them.
+		 */
+		if (perf_evsel__is_dummy(evsel))
+			continue;
+
+		/*
 		 * filters only work for tracepoint event, which doesn't have cpu limit.
 		 * So evlist and evsel should always be same.
 		 */
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 73cf9fc..e307ea2 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2344,3 +2344,35 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel, struct target *target,
 			 err, strerror_r(err, sbuf, sizeof(sbuf)),
 			 perf_evsel__name(evsel));
 }
+
+bool perf_evsel__is_bpf_placeholder(struct perf_evsel *evsel)
+{
+	if (!perf_evsel__is_dummy(evsel))
+		return false;
+	if (!evsel->name)
+		return false;
+	/*
+	 * If evsel->name doesn't starts with 'dummy', it must be a BPF
+	 * place holder.
+	 */
+	if (strncmp(evsel->name, perf_evsel__sw_names[PERF_COUNT_SW_DUMMY],
+			strlen(perf_evsel__sw_names[PERF_COUNT_SW_DUMMY])))
+		return true;
+	/*
+	 * Very rare case: evsel->name is 'dummy_crazy.bpf'.
+	 *
+	 * Let's check name suffix. A bpf file should ends with one of:
+	 * '.o', '.c' or '.bpf'.
+	 */
+#define SUFFIX_CMP(s)\
+	strcmp(evsel->name + strlen(evsel->name) - (sizeof(s) - 1), s)
+
+	if (SUFFIX_CMP(".o") == 0)
+		return true;
+	if (SUFFIX_CMP(".c") == 0)
+		return true;
+	if (SUFFIX_CMP(".bpf") == 0)
+		return true;
+	return false;
+#undef SUFFIX_CMP
+}
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index fd22f83..864fd3f 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -372,11 +372,34 @@ bool perf_evsel__fallback(struct perf_evsel *evsel, int err,
 int perf_evsel__open_strerror(struct perf_evsel *evsel, struct target *target,
 			      int err, char *msg, size_t size);
 
+bool perf_evsel__is_bpf_placeholder(struct perf_evsel *evsel);
+
 static inline int perf_evsel__group_idx(struct perf_evsel *evsel)
 {
 	return evsel->idx - evsel->leader->idx;
 }
 
+static inline bool perf_evsel__is_dummy(struct perf_evsel *evsel)
+{
+	if (!evsel)
+		return false;
+	if (evsel->attr.type != PERF_TYPE_SOFTWARE)
+		return false;
+	if (evsel->attr.config != PERF_COUNT_SW_DUMMY)
+		return false;
+	return true;
+}
+
+static inline int perf_evsel__can_filter(struct perf_evsel *evsel)
+{
+	if (!evsel)
+		return false;
+	if (evsel->attr.type == PERF_TYPE_TRACEPOINT)
+		return true;
+
+	return perf_evsel__is_bpf_placeholder(evsel);
+}
+
 #define for_each_group_member(_evsel, _leader) 					\
 for ((_evsel) = list_entry((_leader)->node.next, struct perf_evsel, node); 	\
      (_evsel) && (_evsel)->leader == (_leader);					\
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index b560f5f..d961e90 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1346,7 +1346,7 @@ static int set_filter(struct perf_evsel *evsel, const void *arg)
 {
 	const char *str = arg;
 
-	if (evsel == NULL || evsel->attr.type != PERF_TYPE_TRACEPOINT) {
+	if (!perf_evsel__can_filter(evsel)) {
 		fprintf(stderr,
 			"--filter option should follow a -e tracepoint option\n");
 		return -1;
@@ -1375,7 +1375,7 @@ static int add_exclude_perf_filter(struct perf_evsel *evsel,
 {
 	char new_filter[64];
 
-	if (evsel == NULL || evsel->attr.type != PERF_TYPE_TRACEPOINT) {
+	if (!perf_evsel__can_filter(evsel)) {
 		fprintf(stderr,
 			"--exclude-perf option should follow a -e tracepoint option\n");
 		return -1;
-- 
1.8.3.4