1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/bpf.h>
3
4 #include <bpf/bpf_helpers.h>
5
6 struct {
7 __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
8 __uint(max_entries, 3);
9 __uint(key_size, sizeof(__u32));
10 __uint(value_size, sizeof(__u32));
11 } jmp_table SEC(".maps");
12
13 #define TAIL_FUNC(x) \
14 SEC("tc") \
15 int classifier_##x(struct __sk_buff *skb) \
16 { \
17 return x; \
18 }
19 TAIL_FUNC(0)
20 TAIL_FUNC(1)
21 TAIL_FUNC(2)
22
23 SEC("tc")
entry(struct __sk_buff * skb)24 int entry(struct __sk_buff *skb)
25 {
26 /* Multiple locations to make sure we patch
27 * all of them.
28 */
29 bpf_tail_call_static(skb, &jmp_table, 0);
30 bpf_tail_call_static(skb, &jmp_table, 0);
31 bpf_tail_call_static(skb, &jmp_table, 0);
32 bpf_tail_call_static(skb, &jmp_table, 0);
33
34 bpf_tail_call_static(skb, &jmp_table, 1);
35 bpf_tail_call_static(skb, &jmp_table, 1);
36 bpf_tail_call_static(skb, &jmp_table, 1);
37 bpf_tail_call_static(skb, &jmp_table, 1);
38
39 bpf_tail_call_static(skb, &jmp_table, 2);
40 bpf_tail_call_static(skb, &jmp_table, 2);
41 bpf_tail_call_static(skb, &jmp_table, 2);
42 bpf_tail_call_static(skb, &jmp_table, 2);
43
44 return 3;
45 }
46
47 char __license[] SEC("license") = "GPL";
48