38 lines · c
1// SPDX-License-Identifier: GPL-2.02#include <linux/bpf.h>3#include <bpf/bpf_helpers.h>4 5struct {6 __uint(type, BPF_MAP_TYPE_PROG_ARRAY);7 __uint(max_entries, 2);8 __uint(key_size, sizeof(__u32));9 __uint(value_size, sizeof(__u32));10} jmp_table SEC(".maps");11 12#define TAIL_FUNC(x) \13 SEC("tc") \14 int classifier_##x(struct __sk_buff *skb) \15 { \16 return x; \17 }18TAIL_FUNC(0)19TAIL_FUNC(1)20 21static __noinline22int subprog_tail(struct __sk_buff *skb)23{24 bpf_tail_call_static(skb, &jmp_table, 0);25 26 return skb->len * 2;27}28 29SEC("tc")30int entry(struct __sk_buff *skb)31{32 bpf_tail_call_static(skb, &jmp_table, 1);33 34 return subprog_tail(skb);35}36 37char __license[] SEC("license") = "GPL";38