tools/testing/selftests/bpf/progs/tailcall_bpf2bpf1.c

   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_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         }
  18 TAIL_FUNC(0)
  19 TAIL_FUNC(1)
  20
  21 static __noinline
  22 int subprog_tail(struct __sk_buff *skb)
  23 {
  24         bpf_tail_call_static(skb, &jmp_table, 0);
  25
  26         return skb->len * 2;
  27 }
  28
  29 SEC("classifier")
  30 int entry(struct __sk_buff *skb)
  31 {
  32         bpf_tail_call_static(skb, &jmp_table, 1);
  33
  34         return subprog_tail(skb);
  35 }
  36
  37 char __license[] SEC("license") = "GPL";
  38 int _version SEC("version") = 1;