bpf: Add cookie in fdinfo for tracing

Add cookie in fdinfo for tracing, the info as follows:

link_type:	tracing
link_id:	6
prog_tag:	9dfdf8ef453843bf
prog_id:	35
attach_type:	25
target_obj_id:	1
target_btf_id:	60355
cookie:	9007199254740992

Signed-off-by: Tao Chen <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

Author: Tao Chen

kernel/bpf/syscall.c

@@ -3403,10 +3403,12 @@ static void bpf_tracing_link_show_fdinfo(const struct bpf_link *link,
 	seq_printf(seq,
 		   "attach_type:\t%d\n"
 		   "target_obj_id:\t%u\n"
-		   "target_btf_id:\t%u\n",
+		   "target_btf_id:\t%u\n"
+		   "cookie:\t%llu\n",
 		   tr_link->attach_type,
 		   target_obj_id,
-		   target_btf_id);
+		   target_btf_id,
+		   tr_link->link.cookie);
 }
 
 static int bpf_tracing_link_fill_link_info(const struct bpf_link *link,