1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/bpf.h>
3 #include <bpf/bpf_helpers.h>
4
5 struct {
6 __uint(type, BPF_MAP_TYPE_ARRAY);
7 __uint(max_entries, 1);
8 __uint(key_size, sizeof(__u32));
9 __uint(value_size, sizeof(__u32));
10 } nop_table SEC(".maps");
11
12 struct {
13 __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
14 __uint(max_entries, 3);
15 __uint(key_size, sizeof(__u32));
16 __uint(value_size, sizeof(__u32));
17 } jmp_table SEC(".maps");
18
19 int count = 0;
20 int noise = 0;
21
22 static __always_inline int subprog_noise(void)
23 {
24 __u32 key = 0;
25
26 bpf_map_lookup_elem(&nop_table, &key);
27 return 0;
28 }
29
30 __noinline
31 int subprog_tail_2(struct __sk_buff *skb)
32 {
33 if (noise)
34 subprog_noise();
35 bpf_tail_call_static(skb, &jmp_table, 2);
36 return skb->len * 3;
37 }
38
39 __noinline
40 int subprog_tail_1(struct __sk_buff *skb)
41 {
42 bpf_tail_call_static(skb, &jmp_table, 1);
43 return skb->len * 2;
44 }
45
46 __noinline
47 int subprog_tail(struct __sk_buff *skb)
48 {
49 bpf_tail_call_static(skb, &jmp_table, 0);
50 return skb->len;
51 }
52
53 SEC("tc")
54 int classifier_1(struct __sk_buff *skb)
55 {
56 return subprog_tail_2(skb);
57 }
58
59 SEC("tc")
60 int classifier_2(struct __sk_buff *skb)
61 {
62 count++;
63 return subprog_tail_2(skb);
64 }
65
66 SEC("tc")
67 int classifier_0(struct __sk_buff *skb)
68 {
69 return subprog_tail_1(skb);
70 }
71
72 SEC("tc")
73 int entry(struct __sk_buff *skb)
74 {
75 return subprog_tail(skb);
76 }
77
78 char __license[] SEC("license") = "GPL";
79
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