// SPDX-License-Identifier: GPL-2.0 #include <linux/bpf.h> #include <bpf/bpf_helpers.h> struct { __uint(type, BPF_MAP_TYPE_PROG_ARRAY); __uint(max_entries, 2); __uint(key_size, sizeof(__u32)); __uint(value_size, sizeof(__u32)); } jmp_table SEC(".maps"); #define TAIL_FUNC(x) \ SEC("classifier/" #x) \ int bpf_func_##x(struct __sk_buff *skb) \ { \ return x; \ } TAIL_FUNC(0) TAIL_FUNC(1) static __noinline int subprog_tail(struct __sk_buff *skb) { bpf_tail_call_static(skb, &jmp_table, 0); return skb->len * 2; } SEC("classifier") int entry(struct __sk_buff *skb) { bpf_tail_call_static(skb, &jmp_table, 1); return subprog_tail(skb); } char __license[] SEC("license") = "GPL"; int _version SEC("version") = 1;