[PATCHv3 bpf-next 12/24] bpf: Add support for tracing_multi link fdinfo

[Jiri Olsa <jolsa@kernel.org>]

Adding tracing_multi link fdinfo support with following output:

pos:    0
flags:  02000000
mnt_id: 19
ino:    3091
link_type:      tracing_multi
link_id:        382
prog_tag:       62073a1123f07ef7
prog_id:        715
cnt:    10
cookie   BTF-id  func
8        91203   bpf_fentry_test1+0x4/0x10
9        91205   bpf_fentry_test2+0x4/0x10
7        91206   bpf_fentry_test3+0x4/0x20
5        91207   bpf_fentry_test4+0x4/0x20
4        91208   bpf_fentry_test5+0x4/0x20
2        91209   bpf_fentry_test6+0x4/0x20
3        91210   bpf_fentry_test7+0x4/0x10
1        91211   bpf_fentry_test8+0x4/0x10
10       91212   bpf_fentry_test9+0x4/0x10
6        91204   bpf_fentry_test10+0x4/0x10

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/trace/bpf_trace.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 761501ce3a5f..41b691e83dc4 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3618,9 +3618,35 @@ static void bpf_tracing_multi_link_dealloc(struct bpf_link *link)
 	kvfree(tr_link);
 }
 
+#ifdef CONFIG_PROC_FS
+static void bpf_tracing_multi_show_fdinfo(const struct bpf_link *link,
+					  struct seq_file *seq)
+{
+	struct bpf_tracing_multi_link *tr_link =
+		container_of(link, struct bpf_tracing_multi_link, link);
+	bool has_cookies = !!tr_link->cookies;
+
+	seq_printf(seq, "cnt:\t%u\n", tr_link->nodes_cnt);
+
+	seq_printf(seq, "%s\t %s\t %s\n", "cookie", "BTF-id", "func");
+	for (int i = 0; i < tr_link->nodes_cnt; i++) {
+		struct bpf_tracing_multi_node *mnode = &tr_link->nodes[i];
+		u32 btf_id;
+
+		bpf_trampoline_unpack_key(mnode->trampoline->key, NULL, &btf_id);
+		seq_printf(seq, "%llu\t %u\t %pS\n",
+			   has_cookies ? tr_link->cookies[i] : 0,
+			   btf_id, (void *) mnode->trampoline->ip);
+	}
+}
+#endif
+
 static const struct bpf_link_ops bpf_tracing_multi_link_lops = {
 	.release = bpf_tracing_multi_link_release,
 	.dealloc_deferred = bpf_tracing_multi_link_dealloc,
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo = bpf_tracing_multi_show_fdinfo,
+#endif
 };
 
 int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
-- 
2.53.0