perf: Stop using deprecated bpf_program__title()

Switch from deprecated bpf_program__title() API to
bpf_program__section_name(). Also drop unnecessary error checks because
neither bpf_program__title() nor bpf_program__section_name() can fail or
return NULL.

Fixes: 52109584 ("libbpf: Deprecate notion of BPF program "title" in favor of "section name"")
Signed-off-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NTobias Klauser <tklauser@distanz.ch>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/bpf/20200908180127.1249-1-andriin@fb.com

tools/perf/util/bpf-loader.c

@@ -328,12 +328,6 @@ config_bpf_program(struct bpf_program *prog)
 	probe_conf.no_inlines = false;
 	probe_conf.force_add = false;
 
-	config_str = bpf_program__title(prog, false);
-	if (IS_ERR(config_str)) {
-		pr_debug("bpf: unable to get title for program\n");
-		return PTR_ERR(config_str);
-	}
-
 	priv = calloc(sizeof(*priv), 1);
 	if (!priv) {
 		pr_debug("bpf: failed to alloc priv\n");
@@ -341,6 +335,7 @@ config_bpf_program(struct bpf_program *prog)
 	}
 	pev = &priv->pev;
 
+	config_str = bpf_program__section_name(prog);
 	pr_debug("bpf: config program '%s'\n", config_str);
 	err = parse_prog_config(config_str, &main_str, &is_tp, pev);
 	if (err)
@@ -454,10 +449,7 @@ preproc_gen_prologue(struct bpf_program *prog, int n,
 	if (err) {
 		const char *title;
 
-		title = bpf_program__title(prog, false);
-		if (!title)
-			title = "[unknown]";
-
+		title = bpf_program__section_name(prog);
 		pr_debug("Failed to generate prologue for program %s\n",
 			 title);
 		return err;