bpf/progs/tailcall_bpf2bpf3.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <linux/bpf.h>
0003 #include <bpf/bpf_helpers.h>
0004 #include "bpf_legacy.h"
0005
0006 struct {
0007     __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
0008     __uint(max_entries, 2);
0009     __uint(key_size, sizeof(__u32));
0010     __uint(value_size, sizeof(__u32));
0011 } jmp_table SEC(".maps");
0012
0013 __noinline
0014 int subprog_tail2(struct __sk_buff *skb)
0015 {
0016     volatile char arr[64] = {};
0017
0018     if (load_word(skb, 0) || load_half(skb, 0))
0019         bpf_tail_call_static(skb, &jmp_table, 10);
0020     else
0021         bpf_tail_call_static(skb, &jmp_table, 1);
0022
0023     return skb->len;
0024 }
0025
0026 static __noinline
0027 int subprog_tail(struct __sk_buff *skb)
0028 {
0029     volatile char arr[64] = {};
0030
0031     bpf_tail_call_static(skb, &jmp_table, 0);
0032
0033     return skb->len * 2;
0034 }
0035
0036 SEC("tc")
0037 int classifier_0(struct __sk_buff *skb)
0038 {
0039     volatile char arr[128] = {};
0040
0041     return subprog_tail2(skb);
0042 }
0043
0044 SEC("tc")
0045 int classifier_1(struct __sk_buff *skb)
0046 {
0047     volatile char arr[128] = {};
0048
0049     return skb->len * 3;
0050 }
0051
0052 SEC("tc")
0053 int entry(struct __sk_buff *skb)
0054 {
0055     volatile char arr[128] = {};
0056
0057     return subprog_tail(skb);
0058 }
0059
0060 char __license[] SEC("license") = "GPL";