[PATCH v3 05/13] perf tools: Support perf event alias name

[Wang Nan <wangnan0@huawei.com>]

From: He Kuang <hekuang@huawei.com>

This patch adds new bison rules for specifying an alias name to a perf
event, which allows cmdline refer to previous defined perf event through
its name. With this patch user can give alias name to a perf event using
following cmdline:

 # perf record -e mypmu=cycles ...

If alias is not provided (normal case):

 # perf record -e cycles ...

It will be set to event's name automatically ('cycles' in the above
example).

To allow parser refer to existing event selector, pass event list to
'struct parse_events_evlist'. perf_evlist__find_evsel_by_alias() is
introduced to get evsel through its alias.

Test result:

Before this patch:

 # ./perf record -e evt=cycles usleep 10
 event syntax error: 'evt=cycles'
                      \___ parser error
 Run 'perf list' for a list of valid events
 [SNIP]

After this patch:

 # ./perf record -e evt=cycles usleep 10
 [ perf record: Woken up 1 times to write data ]
 [ perf record: Captured and wrote 0.012 MB perf.data (2 samples) ]

Signed-off-by: He Kuang <hekuang@huawei.com>
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
---
 tools/perf/util/evlist.c       | 16 ++++++++++++++++
 tools/perf/util/evlist.h       |  4 ++++
 tools/perf/util/evsel.c        |  1 +
 tools/perf/util/evsel.h        |  1 +
 tools/perf/util/parse-events.c | 37 ++++++++++++++++++++++++++++++++-----
 tools/perf/util/parse-events.h |  5 +++++
 tools/perf/util/parse-events.y | 15 ++++++++++++++-
 7 files changed, 73 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index d139219..8dd59aa 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1753,3 +1753,19 @@ void perf_evlist__set_tracking_event(struct perf_evlist *evlist,
 
 	tracking_evsel->tracking = true;
 }
+
+struct perf_evsel *
+perf_evlist__find_evsel_by_alias(struct perf_evlist *evlist,
+				 const char *alias)
+{
+	struct perf_evsel *evsel;
+
+	evlist__for_each(evlist, evsel) {
+		if (!evsel->alias)
+			continue;
+		if (strcmp(alias, evsel->alias) == 0)
+			return evsel;
+	}
+
+	return NULL;
+}
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index a459fe7..4e25342 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -292,4 +292,8 @@ void perf_evlist__set_tracking_event(struct perf_evlist *evlist,
 				     struct perf_evsel *tracking_evsel);
 
 void perf_event_attr__set_max_precise_ip(struct perf_event_attr *attr);
+
+struct perf_evsel *
+perf_evlist__find_evsel_by_alias(struct perf_evlist *evlist, const char *alias);
+
 #endif /* __PERF_EVLIST_H */
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 0a1f4d9..32131fc 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1060,6 +1060,7 @@ void perf_evsel__exit(struct perf_evsel *evsel)
 	thread_map__put(evsel->threads);
 	zfree(&evsel->group_name);
 	zfree(&evsel->name);
+	zfree(&evsel->alias);
 	perf_evsel__object.fini(evsel);
 }
 
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 0e49bd7..51bab0f 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -89,6 +89,7 @@ struct perf_evsel {
 	int			idx;
 	u32			ids;
 	char			*name;
+	char			*alias;
 	double			scale;
 	const char		*unit;
 	struct event_format	*tp_format;
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 95775fe..484c8e4 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -653,9 +653,9 @@ parse_events_config_bpf(struct parse_events_evlist *data,
 			return -EINVAL;
 		}
 
-		err = bpf__config_obj(obj, term, NULL, &error_pos);
+		err = bpf__config_obj(obj, term, data->evlist, &error_pos);
 		if (err) {
-			bpf__strerror_config_obj(obj, term, NULL,
+			bpf__strerror_config_obj(obj, term, data->evlist,
 						 &error_pos, err, errbuf,
 						 sizeof(errbuf));
 			data->error->help = strdup(
@@ -1089,6 +1089,30 @@ int parse_events__modifier_group(struct list_head *list,
 	return parse_events__modifier_event(list, event_mod, true);
 }
 
+int parse_events__set_event_alias(struct parse_events_evlist *data,
+				  struct list_head *list,
+				  const char *str,
+				  void *loc_alias_)
+{
+	struct perf_evsel *evsel;
+	YYLTYPE *loc_alias = loc_alias_;
+
+	if (!str)
+		return 0;
+
+	if (!list_is_singular(list)) {
+		struct parse_events_error *err = data->error;
+
+		err->idx = loc_alias->first_column;
+		err->str = strdup("One alias can be applied to one event only");
+		return -EINVAL;
+	}
+
+	evsel = list_first_entry(list, struct perf_evsel, node);
+	evsel->alias = strdup(str);
+	return evsel->alias ? 0 : -ENOMEM;
+}
+
 void parse_events__set_leader(char *name, struct list_head *list)
 {
 	struct perf_evsel *leader;
@@ -1281,6 +1305,8 @@ int parse_events_name(struct list_head *list, char *name)
 	__evlist__for_each(list, evsel) {
 		if (!evsel->name)
 			evsel->name = strdup(name);
+		if (!evsel->alias)
+			evsel->alias = strdup(name);
 	}
 
 	return 0;
@@ -1442,9 +1468,10 @@ int parse_events(struct perf_evlist *evlist, const char *str,
 		 struct parse_events_error *err)
 {
 	struct parse_events_evlist data = {
-		.list  = LIST_HEAD_INIT(data.list),
-		.idx   = evlist->nr_entries,
-		.error = err,
+		.list   = LIST_HEAD_INIT(data.list),
+		.idx    = evlist->nr_entries,
+		.error  = err,
+		.evlist = evlist,
 	};
 	int ret;
 
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index 84694f3..20ad3c2 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -98,6 +98,7 @@ struct parse_events_evlist {
 	int			   idx;
 	int			   nr_groups;
 	struct parse_events_error *error;
+	struct perf_evlist	  *evlist;
 };
 
 struct parse_events_terms {
@@ -171,4 +172,8 @@ extern int is_valid_tracepoint(const char *event_string);
 int valid_event_mount(const char *eventfs);
 char *parse_events_formats_error_string(char *additional_terms);
 
+int parse_events__set_event_alias(struct parse_events_evlist *data,
+				  struct list_head *list,
+				  const char *str,
+				  void *loc_alias_);
 #endif /* __PERF_PARSE_EVENTS_H */
diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 8992d16..c3cbd7a 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -77,6 +77,7 @@ static inc_group_count(struct list_head *list,
 %type <head> event_bpf_file
 %type <head> event_def
 %type <head> event_mod
+%type <head> event_alias
 %type <head> event_name
 %type <head> event
 %type <head> events
@@ -193,13 +194,25 @@ event_name PE_MODIFIER_EVENT
 event_name
 
 event_name:
-PE_EVENT_NAME event_def
+PE_EVENT_NAME event_alias
 {
 	ABORT_ON(parse_events_name($2, $1));
 	free($1);
 	$$ = $2;
 }
 |
+event_alias
+
+event_alias:
+PE_NAME '=' event_def
+{
+	struct list_head *list = $3;
+	struct parse_events_evlist *data = _data;
+
+	ABORT_ON(parse_events__set_event_alias(data, list, $1, &@1));
+	$$ = list;
+}
+|
 event_def
 
 event_def: event_pmu |
-- 
1.8.3.4