1// SPDX-License-Identifier: GPL-2.0
2#include <linux/bpf.h>
3#include <bpf/bpf_helpers.h>
4
5SEC("xdp")
6int _xdp_adjust_tail_grow(struct xdp_md *xdp)
7{
8	int data_len = bpf_xdp_get_buff_len(xdp);
9	int offset = 0;
10	/* SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) */
11#if defined(__TARGET_ARCH_s390)
12	int tailroom = 512;
13#else
14	int tailroom = 320;
15#endif
16
17	/* Data length determine test case */
18
19	if (data_len == 54) { /* sizeof(pkt_v4) */
20		offset = 4096; /* test too large offset */
21	} else if (data_len == 74) { /* sizeof(pkt_v6) */
22		offset = 40;
23	} else if (data_len == 64) {
24		offset = 128;
25	} else if (data_len == 128) {
26		/* Max tail grow 3520 */
27		offset = 4096 - 256 - tailroom - data_len;
28	} else if (data_len == 9000) {
29		offset = 10;
30	} else if (data_len == 9001) {
31		offset = 4096;
32	} else {
33		return XDP_ABORTED; /* No matching test */
34	}
35
36	if (bpf_xdp_adjust_tail(xdp, offset))
37		return XDP_DROP;
38	return XDP_TX;
39}
40
41char _license[] SEC("license") = "GPL";
42