perf bpf: Clone bpf stdout events in multiple bpf scripts

This patch allows cloning bpf-output event configuration among multiple
bpf scripts. If there exist a map named '__bpf_output__' and not
configured using 'map:__bpf_output__.event=', this patch clones the
configuration of another '__bpf_stdout__' map. For example, following
command:

  # perf trace --ev bpf-output/no-inherit,name=evt/ \
               --ev ./test_bpf_trace.c/map:__bpf_stdout__.event=evt/ \
               --ev ./test_bpf_trace2.c usleep 100000

equals to:

  # perf trace --ev bpf-output/no-inherit,name=evt/ \
               --ev ./test_bpf_trace.c/map:__bpf_stdout__.event=evt/  \
               --ev ./test_bpf_trace2.c/map:__bpf_stdout__.event=evt/ \
               usleep 100000

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Suggested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1460128045-97310-4-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-record.c

@@ -1276,6 +1276,14 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
 	if (err)
 		return err;
 
+	err = bpf__setup_stdout(rec->evlist);
+	if (err) {
+		bpf__strerror_setup_stdout(rec->evlist, err, errbuf, sizeof(errbuf));
+		pr_err("ERROR: Setup BPF stdout failed: %s\n",
+			 errbuf);
+		return err;
+	}
+
 	err = -ENOMEM;
 
 	symbol__init(NULL);

tools/perf/builtin-trace.c

@@ -3273,6 +3273,13 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
 	argc = parse_options_subcommand(argc, argv, trace_options, trace_subcommands,
 				 trace_usage, PARSE_OPT_STOP_AT_NON_OPTION);
 
+	err = bpf__setup_stdout(trace.evlist);
+	if (err) {
+		bpf__strerror_setup_stdout(trace.evlist, err, bf, sizeof(bf));
+		pr_err("ERROR: Setup BPF stdout failed: %s\n", bf);
+		goto out;
+	}
+
 	if (trace.trace_pgfaults) {
 		trace.opts.sample_address = true;
 		trace.opts.sample_time = true;

tools/perf/util/bpf-loader.c

@@ -842,6 +842,58 @@ bpf_map_op__new(struct parse_events_term *term)
 	return op;
 }
 
+static struct bpf_map_op *
+bpf_map_op__clone(struct bpf_map_op *op)
+{
+	struct bpf_map_op *newop;
+
+	newop = memdup(op, sizeof(*op));
+	if (!newop) {
+		pr_debug("Failed to alloc bpf_map_op\n");
+		return NULL;
+	}
+
+	INIT_LIST_HEAD(&newop->list);
+	if (op->key_type == BPF_MAP_KEY_RANGES) {
+		size_t memsz = op->k.array.nr_ranges *
+			       sizeof(op->k.array.ranges[0]);
+
+		newop->k.array.ranges = memdup(op->k.array.ranges, memsz);
+		if (!newop->k.array.ranges) {
+			pr_debug("Failed to alloc indices for map\n");
+			free(newop);
+			return NULL;
+		}
+	}
+
+	return newop;
+}
+
+static struct bpf_map_priv *
+bpf_map_priv__clone(struct bpf_map_priv *priv)
+{
+	struct bpf_map_priv *newpriv;
+	struct bpf_map_op *pos, *newop;
+
+	newpriv = zalloc(sizeof(*newpriv));
+	if (!newpriv) {
+		pr_debug("No enough memory to alloc map private\n");
+		return NULL;
+	}
+	INIT_LIST_HEAD(&newpriv->ops_list);
+
+	list_for_each_entry(pos, &priv->ops_list, list) {
+		newop = bpf_map_op__clone(pos);
+		if (!newop) {
+			bpf_map_priv__purge(newpriv);
+			return NULL;
+		}
+		list_add_tail(&newop->list, &newpriv->ops_list);
+	}
+
+	return newpriv;
+}
+
 static int
 bpf_map__add_op(struct bpf_map *map, struct bpf_map_op *op)
 {
@@ -1417,6 +1469,70 @@ int bpf__apply_obj_config(void)
 	return 0;
 }
 
+#define bpf__for_each_map(pos, obj, objtmp)	\
+	bpf_object__for_each_safe(obj, objtmp)	\
+		bpf_map__for_each(pos, obj)
+
+#define bpf__for_each_stdout_map(pos, obj, objtmp)	\
+	bpf__for_each_map(pos, obj, objtmp) 		\
+		if (bpf_map__get_name(pos) && 		\
+			(strcmp("__bpf_stdout__", 	\
+				bpf_map__get_name(pos)) == 0))
+
+int bpf__setup_stdout(struct perf_evlist *evlist __maybe_unused)
+{
+	struct bpf_map_priv *tmpl_priv = NULL;
+	struct bpf_object *obj, *tmp;
+	struct bpf_map *map;
+	int err;
+	bool need_init = false;
+
+	bpf__for_each_stdout_map(map, obj, tmp) {
+		struct bpf_map_priv *priv;
+
+		err = bpf_map__get_private(map, (void **)&priv);
+		if (err)
+			return -BPF_LOADER_ERRNO__INTERNAL;
+
+		/*
+		 * No need to check map type: type should have been
+		 * verified by kernel.
+		 */
+		if (!need_init && !priv)
+			need_init = !priv;
+		if (!tmpl_priv && priv)
+			tmpl_priv = priv;
+	}
+
+	if (!need_init)
+		return 0;
+
+	if (!tmpl_priv)
+		return 0;
+
+	bpf__for_each_stdout_map(map, obj, tmp) {
+		struct bpf_map_priv *priv;
+
+		err = bpf_map__get_private(map, (void **)&priv);
+		if (err)
+			return -BPF_LOADER_ERRNO__INTERNAL;
+		if (priv)
+			continue;
+
+		priv = bpf_map_priv__clone(tmpl_priv);
+		if (!priv)
+			return -ENOMEM;
+
+		err = bpf_map__set_private(map, priv, bpf_map_priv__clear);
+		if (err) {
+			bpf_map_priv__clear(map, priv);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
 #define ERRNO_OFFSET(e)		((e) - __BPF_LOADER_ERRNO__START)
 #define ERRCODE_OFFSET(c)	ERRNO_OFFSET(BPF_LOADER_ERRNO__##c)
 #define NR_ERRNO	(__BPF_LOADER_ERRNO__END - __BPF_LOADER_ERRNO__START)
@@ -1590,3 +1706,11 @@ int bpf__strerror_apply_obj_config(int err, char *buf, size_t size)
 	bpf__strerror_end(buf, size);
 	return 0;
 }
+
+int bpf__strerror_setup_stdout(struct perf_evlist *evlist __maybe_unused,
+			       int err, char *buf, size_t size)
+{
+	bpf__strerror_head(err, buf, size);
+	bpf__strerror_end(buf, size);
+	return 0;
+}

tools/perf/util/bpf-loader.h

@@ -79,6 +79,11 @@ int bpf__strerror_config_obj(struct bpf_object *obj,
 			     size_t size);
 int bpf__apply_obj_config(void);
 int bpf__strerror_apply_obj_config(int err, char *buf, size_t size);
+
+int bpf__setup_stdout(struct perf_evlist *evlist);
+int bpf__strerror_setup_stdout(struct perf_evlist *evlist, int err,
+			       char *buf, size_t size);
+
 #else
 static inline struct bpf_object *
 bpf__prepare_load(const char *filename __maybe_unused,
@@ -124,6 +129,12 @@ bpf__apply_obj_config(void)
 	return 0;
 }
 
+static inline int
+bpf__setup_stdout(struct perf_evlist *evlist __maybe_unused)
+{
+	return 0;
+}
+
 static inline int
 __bpf_strerror(char *buf, size_t size)
 {
@@ -177,5 +188,13 @@ bpf__strerror_apply_obj_config(int err __maybe_unused,
 {
 	return __bpf_strerror(buf, size);
 }
+
+static inline int
+bpf__strerror_setup_stdout(struct perf_evlist *evlist __maybe_unused,
+			   int err __maybe_unused, char *buf,
+			   size_t size)
+{
+	return __bpf_strerror(buf, size);
+}
 #endif
 #endif