Show the already expose kprobe_multi link info in bpftool. The result as
follows,

$ tools/bpf/bpftool/bpftool link show
4: kprobe_multi  prog 22
        kprobe.multi  func_cnt 7
        addr             func [module]
        ffffffffbbc44f20 schedule_timeout_interruptible
        ffffffffbbc44f60 schedule_timeout_killable
        ffffffffbbc44fa0 schedule_timeout_uninterruptible
        ffffffffbbc44fe0 schedule_timeout_idle
        ffffffffc08028d0 xfs_trans_get_efd [xfs]
        ffffffffc080fa10 xfs_trans_get_buf_map [xfs]
        ffffffffc0813320 xfs_trans_get_dqtrx [xfs]
        pids kprobe_multi(1434978)
5: kprobe_multi  prog 22
        kretprobe.multi  func_cnt 7
        addr             func [module]
        ffffffffbbc44f20 schedule_timeout_interruptible
        ffffffffbbc44f60 schedule_timeout_killable
        ffffffffbbc44fa0 schedule_timeout_uninterruptible
        ffffffffbbc44fe0 schedule_timeout_idle
        ffffffffc08028d0 xfs_trans_get_efd [xfs]
        ffffffffc080fa10 xfs_trans_get_buf_map [xfs]
        ffffffffc0813320 xfs_trans_get_dqtrx [xfs]
        pids kprobe_multi(1434978)

$ tools/bpf/bpftool/bpftool link show -j
[{"id":4,"type":"kprobe_multi","prog_id":22,"retprobe":false,"func_cnt":7,"funcs":[{"addr":18446744072564789024,"func":"schedule_timeout_interruptible","module":""},{"addr":18446744072564789088,"func":"schedule_timeout_killable","module":""},{"addr":18446744072564789152,"func":"schedule_timeout_uninterruptible","module":""},{"addr":18446744072564789216,"func":"schedule_timeout_idle","module":""},{"addr":18446744072644208848,"func":"xfs_trans_get_efd","module":"xfs"},{"addr":18446744072644262416,"func":"xfs_trans_get_buf_map","module":"xfs"},{"addr":18446744072644277024,"func":"xfs_trans_get_dqtrx","module":"xfs"}],"pids":[{"pid":1434978,"comm":"kprobe_multi"}]},{"id":5,"type":"kprobe_multi","prog_id":22,"retprobe":true,"func_cnt":7,"funcs":[{"addr":18446744072564789024,"func":"schedule_timeout_interruptible","module":""},{"addr":18446744072564789088,"func":"schedule_timeout_killable","module":""},{"addr":18446744072564789152,"func":"schedule_timeout_uninterruptible","module":""},{"addr":18446744072564789216,"func":"schedule_timeout_idle","module":""},{"addr":18446744072644208848,"func":"xfs_trans_get_efd","module":"xfs"},{"addr":18446744072644262416,"func":"xfs_trans_get_buf_map","module":"xfs"},{"addr":18446744072644277024,"func":"xfs_trans_get_dqtrx","module":"xfs"}],"pids":[{"pid":1434978,"comm":"kprobe_multi"}]}]

When kptr_restrict is 2, the result is,

$ tools/bpf/bpftool/bpftool link show
4: kprobe_multi  prog 22
        kprobe.multi  func_cnt 7
5: kprobe_multi  prog 22
        kretprobe.multi  func_cnt 7

Signed-off-by: Yafang Shao <redacted>
---
 tools/bpf/bpftool/link.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 108 insertions(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
index 2d78607..8461e6d 100644
--- a/tools/bpf/bpftool/link.c
+++ b/tools/bpf/bpftool/link.c

@@ -14,8 +14,10 @@
 
 #include "json_writer.h"
 #include "main.h"
+#include "xlated_dumper.h"
 
 static struct hashmap *link_table;
+static struct dump_data dd = {};
 
 static int link_parse_fd(int *argc, char ***argv)
 {

@@ -166,6 +168,45 @@ static int get_prog_info(int prog_id, struct bpf_prog_info *info)
 	return err;
 }
 
+static int cmp_u64(const void *A, const void *B)
+{
+	const __u64 *a = A, *b = B;
+
+	return *a - *b;
+}
+
+static void
+show_kprobe_multi_json(struct bpf_link_info *info, json_writer_t *wtr)
+{
+	__u32 i, j = 0;
+	__u64 *addrs;
+
+	jsonw_bool_field(json_wtr, "retprobe",
+			 info->kprobe_multi.flags & BPF_F_KPROBE_MULTI_RETURN);
+	jsonw_uint_field(json_wtr, "func_cnt", info->kprobe_multi.count);
+	jsonw_name(json_wtr, "funcs");
+	jsonw_start_array(json_wtr);
+	addrs = (__u64 *)u64_to_ptr(info->kprobe_multi.addrs);
+	qsort((void *)addrs, info->kprobe_multi.count, sizeof(__u64), cmp_u64);
+
+	/* Load it once for all. */
+	if (!dd.sym_count)
+		kernel_syms_load(&dd);
+	for (i = 0; i < dd.sym_count; i++) {
+		if (dd.sym_mapping[i].address != addrs[j])
+			continue;
+		jsonw_start_object(json_wtr);
+		jsonw_uint_field(json_wtr, "addr", dd.sym_mapping[i].address);
+		jsonw_string_field(json_wtr, "func", dd.sym_mapping[i].name);
+		/* Print none if it is vmlinux */
+		jsonw_string_field(json_wtr, "module", dd.sym_mapping[i].module);