perf bpf: Generalize bpf__setup_stdout()

We will use it to set up other bpf-output events, for instance to
generate augmented syscall entry tracepoints with pointer contents.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-4r7kw0nsyi4vyz6xm1tzx6a3@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/bpf-loader.c

@@ -1535,10 +1535,7 @@ int bpf__apply_obj_config(void)
 			(strcmp(name, 			\
 				bpf_map__name(pos)) == 0))
 
-#define bpf__for_each_stdout_map(pos, obj, objtmp) \
-	 bpf__for_each_map_named(pos, obj, objtmp, "__bpf_stdout__")
-
-int bpf__setup_stdout(struct perf_evlist *evlist)
+int bpf__setup_output_event(struct perf_evlist *evlist, const char *name)
 {
 	struct bpf_map_priv *tmpl_priv = NULL;
 	struct bpf_object *obj, *tmp;
@@ -1547,7 +1544,7 @@ int bpf__setup_stdout(struct perf_evlist *evlist)
 	int err;
 	bool need_init = false;
 
-	bpf__for_each_stdout_map(map, obj, tmp) {
+	bpf__for_each_map_named(map, obj, tmp, name) {
 		struct bpf_map_priv *priv = bpf_map__priv(map);
 
 		if (IS_ERR(priv))
@@ -1567,17 +1564,23 @@ int bpf__setup_stdout(struct perf_evlist *evlist)
 		return 0;
 
 	if (!tmpl_priv) {
-		err = parse_events(evlist, "bpf-output/no-inherit=1,name=__bpf_stdout__/",
-				   NULL);
+		char *event_definition = NULL;
+
+		if (asprintf(&event_definition, "bpf-output/no-inherit=1,name=%s/", name) < 0)
+			return -ENOMEM;
+
+		err = parse_events(evlist, event_definition, NULL);
+		free(event_definition);
+
 		if (err) {
-			pr_debug("ERROR: failed to create bpf-output event\n");
+			pr_debug("ERROR: failed to create the \"%s\" bpf-output event\n", name);
 			return -err;
 		}
 
 		evsel = perf_evlist__last(evlist);
 	}
 
-	bpf__for_each_stdout_map(map, obj, tmp) {
+	bpf__for_each_map_named(map, obj, tmp, name) {
 		struct bpf_map_priv *priv = bpf_map__priv(map);
 
 		if (IS_ERR(priv))
@@ -1609,6 +1612,11 @@ int bpf__setup_stdout(struct perf_evlist *evlist)
 	return 0;
 }
 
+int bpf__setup_stdout(struct perf_evlist *evlist)
+{
+	return bpf__setup_output_event(evlist, "__bpf_stdout__");
+}
+
 #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)

tools/perf/util/bpf-loader.h

@@ -82,6 +82,7 @@ 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__setup_output_event(struct perf_evlist *evlist, const char *name);
 int bpf__strerror_setup_stdout(struct perf_evlist *evlist, int err,
 			       char *buf, size_t size);
 
@@ -138,6 +139,12 @@ bpf__setup_stdout(struct perf_evlist *evlist __maybe_unused)
 	return 0;
 }
 
+static inline int
+bpf__setup_output_event(struct perf_evlist *evlist __maybe_unused, const char *name __maybe_unused)
+{
+	return 0;
+}
+
 static inline int
 __bpf_strerror(char *buf, size_t size)
 {