perf header: Display message if BPF/BTF info is empty

The perf.data file may contain a bpf_prog_info or bpf_btf feature. If
the contents of these are empty then nothing is displayed. Rather than
display nothing and not account for the file space, display an empty
message.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250617223356.2752099-4-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 3f1b78810059ee083dfa9af14ea8514e9369c436..a9538bb1004db1a68678e236629fca0af02722cc 100644 (file)
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1814,6 +1814,9 @@ static void print_bpf_prog_info(struct feat_fd *ff, FILE *fp)
        root = &env->bpf_progs.infos;
        next = rb_first(root);
 
+       if (!next)
+               printf("# bpf_prog_info empty\n");
+
        while (next) {
                struct bpf_prog_info_node *node;
 
@@ -1838,6 +1841,9 @@ static void print_bpf_btf(struct feat_fd *ff, FILE *fp)
        root = &env->bpf_progs.btfs;
        next = rb_first(root);
 
+       if (!next)
+               printf("# btf info empty\n");
+
        while (next) {
                struct btf_node *node;