xref: /openbmc/linux/net/core/tso.c (revision 2a12187d)
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 void tso_build_hdr(const struct sk_buff *skb, char *hdr, struct tso_t *tso,
9 		   int size, bool is_last)
10 {
11 	int hdr_len = skb_transport_offset(skb) + tso->tlen;
12 	int mac_hdr_len = skb_network_offset(skb);
13 
14 	memcpy(hdr, skb->data, hdr_len);
15 	if (!tso->ipv6) {
16 		struct iphdr *iph = (void *)(hdr + mac_hdr_len);
17 
18 		iph->id = htons(tso->ip_id);
19 		iph->tot_len = htons(size + hdr_len - mac_hdr_len);
20 		tso->ip_id++;
21 	} else {
22 		struct ipv6hdr *iph = (void *)(hdr + mac_hdr_len);
23 
24 		iph->payload_len = htons(size + tso->tlen);
25 	}
26 	hdr += skb_transport_offset(skb);
27 	if (tso->tlen != sizeof(struct udphdr)) {
28 		struct tcphdr *tcph = (struct tcphdr *)hdr;
29 
30 		put_unaligned_be32(tso->tcp_seq, &tcph->seq);
31 
32 		if (!is_last) {
33 			/* Clear all special flags for not last packet */
34 			tcph->psh = 0;
35 			tcph->fin = 0;
36 			tcph->rst = 0;
37 		}
38 	} else {
39 		struct udphdr *uh = (struct udphdr *)hdr;
40 
41 		uh->len = htons(sizeof(*uh) + size);
42 	}
43 }
44 EXPORT_SYMBOL(tso_build_hdr);
45 
46 void tso_build_data(const struct sk_buff *skb, struct tso_t *tso, int size)
47 {
48 	tso->tcp_seq += size; /* not worth avoiding this operation for UDP */
49 	tso->size -= size;
50 	tso->data += size;
51 
52 	if ((tso->size == 0) &&
53 	    (tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
54 		skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
55 
56 		/* Move to next segment */
57 		tso->size = skb_frag_size(frag);
58 		tso->data = skb_frag_address(frag);
59 		tso->next_frag_idx++;
60 	}
61 }
62 EXPORT_SYMBOL(tso_build_data);
63 
64 int tso_start(struct sk_buff *skb, struct tso_t *tso)
65 {
66 	int tlen = skb_is_gso_tcp(skb) ? tcp_hdrlen(skb) : sizeof(struct udphdr);
67 	int hdr_len = skb_transport_offset(skb) + tlen;
68 
69 	tso->tlen = tlen;
70 	tso->ip_id = ntohs(ip_hdr(skb)->id);
71 	tso->tcp_seq = (tlen != sizeof(struct udphdr)) ? ntohl(tcp_hdr(skb)->seq) : 0;
72 	tso->next_frag_idx = 0;
73 	tso->ipv6 = vlan_get_protocol(skb) == htons(ETH_P_IPV6);
74 
75 	/* Build first data */
76 	tso->size = skb_headlen(skb) - hdr_len;
77 	tso->data = skb->data + hdr_len;
78 	if ((tso->size == 0) &&
79 	    (tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
80 		skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
81 
82 		/* Move to next segment */
83 		tso->size = skb_frag_size(frag);
84 		tso->data = skb_frag_address(frag);
85 		tso->next_frag_idx++;
86 	}
87 	return hdr_len;
88 }
89 EXPORT_SYMBOL(tso_start);
90