LXR linux/tools/testing/selftests/bpf/progs/tailcall

   1// SPDX-License-Identifier: GPL-2.0
   2#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("classifier/" #x)                   \
  14        int bpf_func_##x(struct __sk_buff *skb) \
  15        {                                       \
  16                return x;                       \
  17        }
  18TAIL_FUNC(0)
  19TAIL_FUNC(1)
  20
  21static __noinline
  22int 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("classifier")
  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";
  38int _version SEC("version") = 1;
  39