[PATCH 09/48] perf tools: Pass tracepoint options to BPF script

From: Wang Nan
Date: Mon Feb 22 2016 - 04:15:29 EST


Users can pass options to tracepoints defined in the BPF script.
For example:

# perf record -e ./test.c/no-inherit/ bash
# dd if=/dev/zero of=/dev/null count=10000
# exit
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.022 MB perf.data (139 samples) ]

(no-inherit works, only sys_read issued by bash is captured, at least
10000 sys_read issued by dd is skipped.)

test.c:

#define SEC(NAME) __attribute__((section(NAME), used))
SEC("func=sys_read")
int bpf_func__sys_read(void *ctx)
{
return 1;
}
char _license[] SEC("license") = "GPL";
int _version SEC("version") = LINUX_VERSION_CODE;

no-inherit is applied to the kprobe event defined in test.c.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
---
tools/perf/tests/bpf.c | 2 +-
tools/perf/util/parse-events.c | 56 +++++++++++++++++++++++++++++++++++++-----
tools/perf/util/parse-events.h | 3 ++-
3 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/tools/perf/tests/bpf.c b/tools/perf/tests/bpf.c
index 4aed5cb..199501c 100644
--- a/tools/perf/tests/bpf.c
+++ b/tools/perf/tests/bpf.c
@@ -112,7 +112,7 @@ static int do_test(struct bpf_object *obj, int (*func)(void),
parse_evlist.error = &parse_error;
INIT_LIST_HEAD(&parse_evlist.list);

- err = parse_events_load_bpf_obj(&parse_evlist, &parse_evlist.list, obj);
+ err = parse_events_load_bpf_obj(&parse_evlist, &parse_evlist.list, obj, NULL);
if (err || list_empty(&parse_evlist.list)) {
pr_debug("Failed to add events selected by BPF\n");
return TEST_FAIL;
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 6e2f203..4c19d5e 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -581,6 +581,7 @@ static int add_tracepoint_multi_sys(struct list_head *list, int *idx,
struct __add_bpf_event_param {
struct parse_events_evlist *data;
struct list_head *list;
+ struct list_head *head_config;
};

static int add_bpf_event(struct probe_trace_event *tev, int fd,
@@ -597,7 +598,8 @@ static int add_bpf_event(struct probe_trace_event *tev, int fd,
tev->group, tev->event, fd);

err = parse_events_add_tracepoint(&new_evsels, &evlist->idx, tev->group,
- tev->event, evlist->error, NULL);
+ tev->event, evlist->error,
+ param->head_config);
if (err) {
struct perf_evsel *evsel, *tmp;

@@ -622,11 +624,12 @@ static int add_bpf_event(struct probe_trace_event *tev, int fd,

int parse_events_load_bpf_obj(struct parse_events_evlist *data,
struct list_head *list,
- struct bpf_object *obj)
+ struct bpf_object *obj,
+ struct list_head *head_config)
{
int err;
char errbuf[BUFSIZ];
- struct __add_bpf_event_param param = {data, list};
+ struct __add_bpf_event_param param = {data, list, head_config};
static bool registered_unprobe_atexit = false;

if (IS_ERR(obj) || !obj) {
@@ -720,14 +723,47 @@ parse_events_config_bpf(struct parse_events_evlist *data,
return 0;
}

+/*
+ * Split config terms:
+ * perf record -e bpf.c/call-graph=fp,map:array.value[0]=1/ ...
+ * 'call-graph=fp' is 'evt config', should be applied to each
+ * events in bpf.c.
+ * 'map:array.value[0]=1' is 'obj config', should be processed
+ * with parse_events_config_bpf.
+ *
+ * Move object config terms from the first list to obj_head_config.
+ */
+static void
+split_bpf_config_terms(struct list_head *evt_head_config,
+ struct list_head *obj_head_config)
+{
+ struct parse_events_term *term, *temp;
+
+ /*
+ * Currectly, all possible user config term
+ * belong to bpf object. parse_events__is_hardcoded_term()
+ * happends to be a good flag.
+ *
+ * See parse_events_config_bpf() and
+ * config_term_tracepoint().
+ */
+ list_for_each_entry_safe(term, temp, evt_head_config, list)
+ if (!parse_events__is_hardcoded_term(term))
+ list_move_tail(&term->list, obj_head_config);
+}
+
int parse_events_load_bpf(struct parse_events_evlist *data,
struct list_head *list,
char *bpf_file_name,
bool source,
struct list_head *head_config)
{
- struct bpf_object *obj;
int err;
+ struct bpf_object *obj;
+ LIST_HEAD(obj_head_config);
+
+ if (head_config)
+ split_bpf_config_terms(head_config, &obj_head_config);

obj = bpf__prepare_load(bpf_file_name, source);
if (IS_ERR(obj)) {
@@ -749,10 +785,18 @@ int parse_events_load_bpf(struct parse_events_evlist *data,
return err;
}

- err = parse_events_load_bpf_obj(data, list, obj);
+ err = parse_events_load_bpf_obj(data, list, obj, head_config);
if (err)
return err;
- return parse_events_config_bpf(data, obj, head_config);
+ err = parse_events_config_bpf(data, obj, &obj_head_config);
+
+ /*
+ * Caller doesn't know anything about obj_head_config,
+ * so combine them together again before returnning.
+ */
+ if (head_config)
+ list_splice_tail(&obj_head_config, head_config);
+ return err;
}

static int
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index e445622..67e4930 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -146,7 +146,8 @@ int parse_events_load_bpf(struct parse_events_evlist *data,
struct bpf_object;
int parse_events_load_bpf_obj(struct parse_events_evlist *data,
struct list_head *list,
- struct bpf_object *obj);
+ struct bpf_object *obj,
+ struct list_head *head_config);
int parse_events_add_numeric(struct parse_events_evlist *data,
struct list_head *list,
u32 type, u64 config,
--
1.8.3.4