bpf/progs/tailcall_bpf2bpf1.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <linux/bpf.h>
0003 #include <bpf/bpf_helpers.h>
0004
0005 struct {
0006     __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
0007     __uint(max_entries, 2);
0008     __uint(key_size, sizeof(__u32));
0009     __uint(value_size, sizeof(__u32));
0010 } jmp_table SEC(".maps");
0011
0012 #define TAIL_FUNC(x)                \
0013     SEC("tc")               \
0014     int classifier_##x(struct __sk_buff *skb)   \
0015     {                   \
0016         return x;           \
0017     }
0018 TAIL_FUNC(0)
0019 TAIL_FUNC(1)
0020
0021 static __noinline
0022 int subprog_tail(struct __sk_buff *skb)
0023 {
0024     bpf_tail_call_static(skb, &jmp_table, 0);
0025
0026     return skb->len * 2;
0027 }
0028
0029 SEC("tc")
0030 int entry(struct __sk_buff *skb)
0031 {
0032     bpf_tail_call_static(skb, &jmp_table, 1);
0033
0034     return subprog_tail(skb);
0035 }
0036
0037 char __license[] SEC("license") = "GPL";