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 __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