[PATCH 31/31] perf tools: Enable BPF object configure syntax

[Wang Nan]

This patch adds the final step for BPF map configuration. A new syntax
is appended into parser so user can config BPF objects through '/' '/'
enclosed config terms.

After this patch, BPF programs for perf are finally able to utilize
bpf_perf_event_read() introduced in commit 35578d7984003097af2b1e3
(bpf: Implement function bpf_perf_event_read() that get the selected
hardware PMU conuter) by following way:

 ===== BPF program bpf_program.c =====

 struct bpf_map_def SEC("maps") pmu_map = {
     .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
     .key_size = sizeof(int),
     .value_size = sizeof(u32),
     .max_entries = __NR_CPUS__,
 };

 SEC("func_write=sys_write")
 int func_write(void *ctx)
 {
     unsigned long long val;
     char fmt[] = "sys_write:        pmu=%llu\n";
     val = bpf_perf_event_read(&pmu_map, bpf_get_smp_processor_id());
     bpf_trace_printk(fmt, sizeof(fmt), val);
     return 0;
 }

 SEC("func_write_return=sys_write%return")
 int func_write_return(void *ctx)
 {
     unsigned long long val = 0;
     char fmt[] = "sys_write_return: pmu=%llu\n";
     val = bpf_perf_event_read(&pmu_map, bpf_get_smp_processor_id());
     bpf_trace_printk(fmt, sizeof(fmt), val);
     return 0;
 }

 ===== cmdline =====
 # echo "" > /sys/kernel/debug/tracing/trace
 # perf record -e evt=cycles/period=0x7fffffffffffffff/ \
               -e bpf_program.c/maps.pmu_map.event=evt/
               -a ls
 # cat /sys/kernel/debug/tracing/trace | grep ls
              ls-3363  [003] d... 75475.056190: : sys_write:        pmu=3961415
              ls-3363  [003] dN.. 75475.056212: : sys_write_return: pmu=4051390
              ls-3363  [003] d... 75475.056216: : sys_write:        pmu=4065447
              ls-3363  [003] dN.. 75475.056227: : sys_write_return: pmu=4109760
              ls-3363  [003] d... 75475.056230: : sys_write:        pmu=4120776
              ls-3363  [003] dN.. 75475.056245: : sys_write_return: pmu=4178441
              ...
 # perf report --stdio
Error:
The perf.data file has no samples!

Where, setting period of cycles Set a very large value to period
of cycles event because we want to use this event as a counter
only, don't need sampling.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kaixu Xia <xiakaixu@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/n/ebpf-2mjd96mowgzslkj8jrwbnwg7@xxxxxxxxxxxxxx
---
 tools/perf/util/parse-events.c | 71 ++++++++++++++++++++++++++++++++++++++++--
 tools/perf/util/parse-events.h |  3 +-
 tools/perf/util/parse-events.y | 19 ++++++++---
 3 files changed, 85 insertions(+), 8 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 06ba5a6..f8b2bb8 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -624,17 +624,79 @@ errout:
 	return err;
 }
 
+static int
+parse_events_config_bpf(struct parse_events_evlist *data,
+		       struct bpf_object *obj,
+		       struct list_head *head_config)
+{
+	struct parse_events_term *term;
+
+	if (!head_config || list_empty(head_config))
+		return 0;
+
+	list_for_each_entry(term, head_config, list) {
+		struct bpf_config_val val;
+		char errbuf[BUFSIZ];
+		int err;
+
+		if (term->type_term != PARSE_EVENTS__TERM_TYPE_USER) {
+			snprintf(errbuf, sizeof(errbuf),
+				 "Invalid config term for BPF object");
+			errbuf[BUFSIZ - 1] = '\0';
+
+			data->error->idx = term->err_term;
+			data->error->str = strdup(errbuf);
+			return -EINVAL;
+		}
+
+		switch (term->type_val) {
+		case PARSE_EVENTS__TERM_TYPE_NUM:
+			val.type = BPF_CONFIG_VAL_NUM;
+			val.num = (unsigned long long)term->val.num;
+			break;
+		case PARSE_EVENTS__TERM_TYPE_STR:
+			val.type = BPF_CONFIG_VAL_STRING;
+			val.string = term->val.str;
+			break;
+		default:
+			data->error->idx = term->err_val;
+			data->error->str = strdup("Invalid config value");
+			return -EINVAL;
+		}
+
+		err = bpf__config_obj(obj, term->config, &val, data->evlist);
+		if (err) {
+			bpf__strerror_config_obj(obj, term->config, &val,
+						 data->evlist, err, errbuf,
+						 sizeof(errbuf));
+			data->error->help = strdup(
+"Hint:\tValid config term:\n"
+"     \tmaps.<mapname>.event\n"
+"     \t(add -v to see detail)");
+			data->error->str = strdup(errbuf);
+			if (err == -EINVAL)
+				data->error->idx = term->err_val;
+			else
+				data->error->idx = term->err_term;
+			return err;
+		}
+	}
+	return 0;
+
+}
+
 int parse_events_load_bpf(struct parse_events_evlist *data,
 			  struct list_head *list,
 			  char *bpf_file_name,
-			  bool source)
+			  bool source,
+			  struct list_head *head_config)
 {
 	struct bpf_object *obj;
+	int err;
 
 	obj = bpf__prepare_load(bpf_file_name, source);
 	if (IS_ERR(obj) || !obj) {
 		char errbuf[BUFSIZ];
-		int err;
 
 		err = obj ? PTR_ERR(obj) : -EINVAL;
 
@@ -651,7 +713,10 @@ int parse_events_load_bpf(struct parse_events_evlist *data,
 		return err;
 	}
 
-	return parse_events_load_bpf_obj(data, list, obj);
+	err = parse_events_load_bpf_obj(data, list, obj);
+	if (err)
+		return err;
+	return parse_events_config_bpf(data, obj, head_config);
 }
 
 static int
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index b525353..d4aa88e 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -125,7 +125,8 @@ int parse_events_add_tracepoint(struct list_head *list, int *idx,
 int parse_events_load_bpf(struct parse_events_evlist *data,
 			  struct list_head *list,
 			  char *bpf_file_name,
-			  bool source);
+			  bool source,
+			  struct list_head *head_config);
 /* Provide this function for perf test */
 struct bpf_object;
 int parse_events_load_bpf_obj(struct parse_events_evlist *data,
diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 90e382f..545bce5 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -64,6 +64,7 @@ static inc_group_count(struct list_head *list,
 %type <str> PE_PMU_EVENT_PRE PE_PMU_EVENT_SUF PE_KERNEL_PMU_EVENT
 %type <num> value_sym
 %type <head> event_config
+%type <head> event_bpf_config
 %type <term> event_term
 %type <head> event_pmu
 %type <head> event_legacy_symbol
@@ -468,27 +469,37 @@ PE_RAW
 }
 
 event_bpf_file:
-PE_BPF_OBJECT
+PE_BPF_OBJECT event_bpf_config
 {
 	struct parse_events_evlist *data = _data;
 	struct parse_events_error *error = data->error;
 	struct list_head *list;
 
 	ALLOC_LIST(list);
-	ABORT_ON(parse_events_load_bpf(data, list, $1, false));
+	ABORT_ON(parse_events_load_bpf(data, list, $1, false, $2));
 	$$ = list;
 }
 |
-PE_BPF_SOURCE
+PE_BPF_SOURCE event_bpf_config
 {
 	struct parse_events_evlist *data = _data;
 	struct list_head *list;
 
 	ALLOC_LIST(list);
-	ABORT_ON(parse_events_load_bpf(data, list, $1, true));
+	ABORT_ON(parse_events_load_bpf(data, list, $1, true, $2));
 	$$ = list;
 }
 
+event_bpf_config:
+'/' event_config '/'
+{
+	$$ = $2;
+}
+|
+{
+	$$ = NULL;
+}
+
 start_terms: event_config
 {
 	struct parse_events_terms *data = _data;
-- 
1.8.3.4

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