1// SPDX-License-Identifier: GPL-2.0
 2#include <linux/export.h>
 3#include <linux/if_vlan.h>
 4#include <net/ip.h>
 5#include <net/tso.h>
 6#include <asm/unaligned.h>
 7
 8/* Calculate expected number of TX descriptors */
 9int tso_count_descs(const struct sk_buff *skb)
10{
11	/* The Marvell Way */
12	return skb_shinfo(skb)->gso_segs * 2 + skb_shinfo(skb)->nr_frags;
13}
14EXPORT_SYMBOL(tso_count_descs);
15
16void tso_build_hdr(const struct sk_buff *skb, char *hdr, struct tso_t *tso,
17		   int size, bool is_last)
18{
19	int hdr_len = skb_transport_offset(skb) + tso->tlen;
20	int mac_hdr_len = skb_network_offset(skb);
21
22	memcpy(hdr, skb->data, hdr_len);
23	if (!tso->ipv6) {
24		struct iphdr *iph = (void *)(hdr + mac_hdr_len);
25
26		iph->id = htons(tso->ip_id);
27		iph->tot_len = htons(size + hdr_len - mac_hdr_len);
28		tso->ip_id++;
29	} else {
30		struct ipv6hdr *iph = (void *)(hdr + mac_hdr_len);
31
32		iph->payload_len = htons(size + tso->tlen);
33	}
34	hdr += skb_transport_offset(skb);
35	if (tso->tlen != sizeof(struct udphdr)) {
36		struct tcphdr *tcph = (struct tcphdr *)hdr;
37
38		put_unaligned_be32(tso->tcp_seq, &tcph->seq);
39
40		if (!is_last) {
41			/* Clear all special flags for not last packet */
42			tcph->psh = 0;
43			tcph->fin = 0;
44			tcph->rst = 0;
45		}
46	} else {
47		struct udphdr *uh = (struct udphdr *)hdr;
48
49		uh->len = htons(sizeof(*uh) + size);
50	}
51}
52EXPORT_SYMBOL(tso_build_hdr);
53
54void tso_build_data(const struct sk_buff *skb, struct tso_t *tso, int size)
55{
56	tso->tcp_seq += size; /* not worth avoiding this operation for UDP */
57	tso->size -= size;
58	tso->data += size;
59
60	if ((tso->size == 0) &&
61	    (tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
62		skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
63
64		/* Move to next segment */
65		tso->size = skb_frag_size(frag);
66		tso->data = skb_frag_address(frag);
67		tso->next_frag_idx++;
68	}
69}
70EXPORT_SYMBOL(tso_build_data);
71
72int tso_start(struct sk_buff *skb, struct tso_t *tso)
73{
74	int tlen = skb_is_gso_tcp(skb) ? tcp_hdrlen(skb) : sizeof(struct udphdr);
75	int hdr_len = skb_transport_offset(skb) + tlen;
76
77	tso->tlen = tlen;
78	tso->ip_id = ntohs(ip_hdr(skb)->id);
79	tso->tcp_seq = (tlen != sizeof(struct udphdr)) ? ntohl(tcp_hdr(skb)->seq) : 0;
80	tso->next_frag_idx = 0;
81	tso->ipv6 = vlan_get_protocol(skb) == htons(ETH_P_IPV6);
82
83	/* Build first data */
84	tso->size = skb_headlen(skb) - hdr_len;
85	tso->data = skb->data + hdr_len;
86	if ((tso->size == 0) &&
87	    (tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
88		skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
89
90		/* Move to next segment */
91		tso->size = skb_frag_size(frag);
92		tso->data = skb_frag_address(frag);
93		tso->next_frag_idx++;
94	}
95	return hdr_len;
96}
97EXPORT_SYMBOL(tso_start);