1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/bpf.h>
3 #include <bpf/bpf_helpers.h>
4 
5 SEC("xdp")
6 int _xdp_adjust_tail_grow(struct xdp_md *xdp)
7 {
8 	void *data_end = (void *)(long)xdp->data_end;
9 	void *data = (void *)(long)xdp->data;
10 	unsigned int data_len;
11 	int offset = 0;
12 
13 	/* Data length determine test case */
14 	data_len = data_end - data;
15 
16 	if (data_len == 54) { /* sizeof(pkt_v4) */
17 		offset = 4096; /* test too large offset */
18 	} else if (data_len == 74) { /* sizeof(pkt_v6) */
19 		offset = 40;
20 	} else if (data_len == 64) {
21 		offset = 128;
22 	} else if (data_len == 128) {
23 		offset = 4096 - 256 - 320 - data_len; /* Max tail grow 3520 */
24 	} else {
25 		return XDP_ABORTED; /* No matching test */
26 	}
27 
28 	if (bpf_xdp_adjust_tail(xdp, offset))
29 		return XDP_DROP;
30 	return XDP_TX;
31 }
32 
33 char _license[] SEC("license") = "GPL";
34