// SPDX-License-Identifier: GPL-2.0 #include <linux/bpf.h> #include <bpf/bpf_helpers.h> struct { __uint(type, BPF_MAP_TYPE_ARRAY); __uint(max_entries, 1); __uint(key_size, sizeof(__u32)); __uint(value_size, sizeof(__u32)); } nop_table SEC(".maps"); struct { __uint(type, BPF_MAP_TYPE_PROG_ARRAY); __uint(max_entries, 3); __uint(key_size, sizeof(__u32)); __uint(value_size, sizeof(__u32)); } jmp_table SEC(".maps"); int count = 0; int noise = 0; static __always_inline int subprog_noise(void) { __u32 key = 0; bpf_map_lookup_elem(&nop_table, &key); return 0; } __noinline int subprog_tail_2(struct __sk_buff *skb) { if (noise) subprog_noise(); bpf_tail_call_static(skb, &jmp_table, 2); return skb->len * 3; } __noinline int subprog_tail_1(struct __sk_buff *skb) { bpf_tail_call_static(skb, &jmp_table, 1); return skb->len * 2; } __noinline int subprog_tail(struct __sk_buff *skb) { bpf_tail_call_static(skb, &jmp_table, 0); return skb->len; } SEC("tc") int classifier_1(struct __sk_buff *skb) { return subprog_tail_2(skb); } SEC("tc") int classifier_2(struct __sk_buff *skb) { count++; return subprog_tail_2(skb); } SEC("tc") int classifier_0(struct __sk_buff *skb) { return subprog_tail_1(skb); } SEC("tc") int entry(struct __sk_buff *skb) { return subprog_tail(skb); } char __license[] SEC("license") = "GPL";