backport: import TSO helpers with support for IPv6

Note that TSO core helpers have been implemented in 3.19,
but support for IPv6 was added in 4.4 only.
iwlwifi will soon need this.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
[use skb_frag_page(frag), move the includes to the top and add missing ones.]
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

2 files changed, 121 insertions, 0 deletions

diff --git a/backport/backport-include/net/tso.h b/backport/backport-include/net/tso.h
new file mode 100644
index 00000000..816928c3
--- /dev/null
+++ b/backport/backport-include/net/tso.h
@@ -0,0 +1,33 @@
+#ifndef BACKPORT_TSO_H
+#define BACKPORT_TSO_H
+
+#include <net/ip.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4,4,0)
+
+#define tso_t LINUX_BACKPORT(tso_t)
+struct tso_t {
+	int next_frag_idx;
+	void *data;
+	size_t size;
+	u16 ip_id;
+	bool ipv6;
+	u32 tcp_seq;
+};
+
+#define tso_count_descs LINUX_BACKPORT(tso_count_descs)
+int tso_count_descs(struct sk_buff *skb);
+
+#define tso_build_hdr LINUX_BACKPORT(tso_build_hdr)
+void tso_build_hdr(struct sk_buff *skb, char *hdr, struct tso_t *tso,
+		   int size, bool is_last);
+#define tso_build_data LINUX_BACKPORT(tso_build_data)
+void tso_build_data(struct sk_buff *skb, struct tso_t *tso, int size);
+#define tso_start LINUX_BACKPORT(tso_start)
+void tso_start(struct sk_buff *skb, struct tso_t *tso);
+
+#else
+#include_next <net/tso.h>
+#endif
+
+#endif	/* BACKPORT_TSO_H */
diff --git a/backport/compat/backport-4.4.c b/backport/compat/backport-4.4.c
index 43e26e55..88543859 100644
--- a/backport/compat/backport-4.4.c
+++ b/backport/compat/backport-4.4.c
@@ -9,8 +9,15 @@
  */
 
 #include <linux/debugfs.h>
+#include <linux/export.h>
 #include <linux/uaccess.h>
 #include <linux/fs.h>
+#include <linux/if_vlan.h>
+#include <linux/mm.h>
+#include <linux/skbuff.h>
+#include <net/ip.h>
+#include <net/tso.h>
+#include <asm/unaligned.h>
 
 #ifdef CONFIG_DEBUG_FS
 #if LINUX_VERSION_CODE < KERNEL_VERSION(4,3,0)
@@ -64,3 +71,84 @@ struct dentry *debugfs_create_bool(const char *name, umode_t mode,
 }
 EXPORT_SYMBOL_GPL(debugfs_create_bool);
 #endif /* CONFIG_DEBUG_FS */
+
+/* Calculate expected number of TX descriptors */
+int tso_count_descs(struct sk_buff *skb)
+{
+	/* The Marvell Way */
+	return skb_shinfo(skb)->gso_segs * 2 + skb_shinfo(skb)->nr_frags;
+}
+EXPORT_SYMBOL(tso_count_descs);
+
+void tso_build_hdr(struct sk_buff *skb, char *hdr, struct tso_t *tso,
+		   int size, bool is_last)
+{
+	struct tcphdr *tcph;
+	int hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
+	int mac_hdr_len = skb_network_offset(skb);
+
+	memcpy(hdr, skb->data, hdr_len);
+	if (!tso->ipv6) {
+		struct iphdr *iph = (void *)(hdr + mac_hdr_len);
+
+		iph->id = htons(tso->ip_id);
+		iph->tot_len = htons(size + hdr_len - mac_hdr_len);
+		tso->ip_id++;
+	} else {
+		struct ipv6hdr *iph = (void *)(hdr + mac_hdr_len);
+
+		iph->payload_len = htons(size + tcp_hdrlen(skb));
+	}
+	tcph = (struct tcphdr *)(hdr + skb_transport_offset(skb));
+	put_unaligned_be32(tso->tcp_seq, &tcph->seq);
+
+	if (!is_last) {
+		/* Clear all special flags for not last packet */
+		tcph->psh = 0;
+		tcph->fin = 0;
+		tcph->rst = 0;
+	}
+}
+EXPORT_SYMBOL(tso_build_hdr);
+
+void tso_build_data(struct sk_buff *skb, struct tso_t *tso, int size)
+{
+	tso->tcp_seq += size;
+	tso->size -= size;
+	tso->data += size;
+
+	if ((tso->size == 0) &&
+	    (tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
+		skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
+
+		/* Move to next segment */
+		tso->size = frag->size;
+		tso->data = page_address(skb_frag_page(frag)) + frag->page_offset;
+		tso->next_frag_idx++;
+	}
+}
+EXPORT_SYMBOL(tso_build_data);
+
+void tso_start(struct sk_buff *skb, struct tso_t *tso)
+{
+	int hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
+
+	tso->ip_id = ntohs(ip_hdr(skb)->id);
+	tso->tcp_seq = ntohl(tcp_hdr(skb)->seq);
+	tso->next_frag_idx = 0;
+	tso->ipv6 = vlan_get_protocol(skb) == htons(ETH_P_IPV6);
+
+	/* Build first data */
+	tso->size = skb_headlen(skb) - hdr_len;
+	tso->data = skb->data + hdr_len;
+	if ((tso->size == 0) &&
+	    (tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
+		skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
+
+		/* Move to next segment */
+		tso->size = frag->size;
+		tso->data = page_address(skb_frag_page(frag)) + frag->page_offset;
+		tso->next_frag_idx++;
+	}
+}
+EXPORT_SYMBOL(tso_start);