1// SPDX-License-Identifier: GPL-2.0
2#include <linux/bpf.h>
3#include <bpf/bpf_helpers.h>
4#include "bpf_legacy.h"
5
6struct {
7 __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
8 __uint(max_entries, 1);
9 __uint(key_size, sizeof(__u32));
10 __uint(value_size, sizeof(__u32));
11} jmp_table SEC(".maps");
12
13static __noinline
14int subprog_tail(struct __sk_buff *skb)
15{
16 if (load_byte(skb, 0))
17 bpf_tail_call_static(skb, &jmp_table, 1);
18 else
19 bpf_tail_call_static(skb, &jmp_table, 0);
20 return 1;
21}
22
23int count = 0;
24
25SEC("tc")
26int classifier_0(struct __sk_buff *skb)
27{
28 count++;
29 return subprog_tail(skb);
30}
31
32SEC("tc")
33int entry(struct __sk_buff *skb)
34{
35 bpf_tail_call_static(skb, &jmp_table, 0);
36
37 return 0;
38}
39
40char __license[] SEC("license") = "GPL";
41

source code of linux/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf2.c