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 	int data_len = bpf_xdp_get_buff_len(xdp);
11 	int offset = 0;
12 
13 	/* Data length determine test case */
14 
15 	if (data_len == 54) { /* sizeof(pkt_v4) */
16 		offset = 4096; /* test too large offset */
17 	} else if (data_len == 74) { /* sizeof(pkt_v6) */
18 		offset = 40;
19 	} else if (data_len == 64) {
20 		offset = 128;
21 	} else if (data_len == 128) {
22 		/* Max tail grow 3520 */
23 		offset = 4096 - 256 - 320 - data_len;
24 	} else if (data_len == 9000) {
25 		offset = 10;
26 	} else if (data_len == 9001) {
27 		offset = 4096;
28 	} else {
29 		return XDP_ABORTED; /* No matching test */
30 	}
31 
32 	if (bpf_xdp_adjust_tail(xdp, offset))
33 		return XDP_DROP;
34 	return XDP_TX;
35 }
36 
37 char _license[] SEC("license") = "GPL";
38