1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/bpf.h>
3 #include <bpf/bpf_helpers.h>
4 
5 #define __unused __attribute__((unused))
6 
7 struct {
8 	__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
9 	__uint(max_entries, 1);
10 	__uint(key_size, sizeof(__u32));
11 	__uint(value_size, sizeof(__u32));
12 } jmp_table SEC(".maps");
13 
14 int done = 0;
15 
16 SEC("tc")
17 int classifier_0(struct __sk_buff *skb __unused)
18 {
19 	done = 1;
20 	return 0;
21 }
22 
23 static __noinline
24 int subprog_tail(struct __sk_buff *skb)
25 {
26 	/* Don't propagate the constant to the caller */
27 	volatile int ret = 1;
28 
29 	bpf_tail_call_static(skb, &jmp_table, 0);
30 	return ret;
31 }
32 
33 SEC("tc")
34 int entry(struct __sk_buff *skb)
35 {
36 	/* Have data on stack which size is not a multiple of 8 */
37 	volatile char arr[1] = {};
38 
39 	return subprog_tail(skb);
40 }
41 
42 char __license[] SEC("license") = "GPL";
43