net/core/tso.c

   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 */
   9 int 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 }
  14 EXPORT_SYMBOL(tso_count_descs);
  15
  16 void 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 }
  52 EXPORT_SYMBOL(tso_build_hdr);
  53
  54 void 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 }
  70 EXPORT_SYMBOL(tso_build_data);
  71
  72 int 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 }
  97 EXPORT_SYMBOL(tso_start);