// SPDX-License-Identifier: GPL-2.0
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>

SEC("xdp")
int _xdp_adjust_tail_grow(struct xdp_md *xdp)
{
        int data_len = bpf_xdp_get_buff_len(xdp);
        int offset = 0;
        /* SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) */
#if defined(__TARGET_ARCH_s390)
        int tailroom = 512;
#elif defined(__TARGET_ARCH_powerpc)
        int tailroom = 384;
#else
        int tailroom = 320;
#endif

        /* Data length determine test case */

        if (data_len == 54) { /* sizeof(pkt_v4) */
                offset = 4096; /* test too large offset, 4k page size */
        } else if (data_len == 53) { /* sizeof(pkt_v4) - 1 */
                offset = 65536; /* test too large offset, 64k page size */
        } else if (data_len == 74) { /* sizeof(pkt_v6) */
                offset = 40;
        } else if (data_len == 64) {
                offset = 128;
        } else if (data_len == 128) {
                /* Max tail grow 3520 */
                offset = 4096 - 256 - tailroom - data_len;
        } else if (data_len == 9000) {
                offset = 10;
        } else if (data_len == 9001) {
                offset = 4096;
        } else if (data_len == 90000) {
                offset = 10; /* test a small offset, 64k page size */
        } else if (data_len == 90001) {
                offset = 65536; /* test too large offset, 64k page size */
        } else {
                return XDP_ABORTED; /* No matching test */
        }

        if (bpf_xdp_adjust_tail(xdp, offset))
                return XDP_DROP;
        return XDP_TX;
}

char _license[] SEC("license") = "GPL";