net: erspan: use bitfield instead of mask and offset

Originally the erspan fields are defined as a group into a __be16 field,
and use mask and offset to access each field. This is more costly due to
calling ntohs/htons. The patch changes it to use bitfields.

Signed-off-by: William Tu <[e-mail]>
Acked-by: Pravin B Shelar <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/erspan.h

···
 #define GRA_MASK	0x0006
 #define O_MASK		0x0001
 
+#define HWID_OFFSET    4
+#define DIR_OFFSET     3
+
 /* ERSPAN version 2 metadata header */
 struct erspan_md2 {
 	__be32 timestamp;
 	__be16 sgt;	/* security group tag */
-	__be16 flags;
-#define P_OFFSET	15
-#define FT_OFFSET	10
-#define HWID_OFFSET	4
-#define DIR_OFFSET	3
-#define GRA_OFFSET	1
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u8	hwid_upper:2,
+		ft:5,
+		p:1;
+	__u8	o:1,
+		gra:2,
+		dir:1,
+		hwid:4;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u8	p:1,
+		ft:5,
+		hwid_upper:2;
+	__u8	hwid:4,
+		dir:1,
+		gra:2,
+		o:1;
+#endif
 };
 
 enum erspan_encap_type {
···
 };
 
 struct erspan_base_hdr {
-	__be16 ver_vlan;
-#define VER_OFFSET  12
-	__be16 session_id;
-#define COS_OFFSET  13
-#define EN_OFFSET   11
-#define BSO_OFFSET  EN_OFFSET
-#define T_OFFSET    10
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u8	vlan_upper:4,
+		ver:4;
+	__u8	vlan:8;
+	__u8	session_id_upper:2,
+		t:1,
+		en:2,
+		cos:3;
+	__u8	session_id:8;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u8	ver: 4,
+		vlan_upper:4;
+	__u8	vlan:8;
+	__u8	cos:3,
+		en:2,
+		t:1,
+		session_id_upper:2;
+	__u8	session_id:8;
+#else
+#error "Please fix <asm/byteorder.h>"
+#endif
 };
+
+static inline void set_session_id(struct erspan_base_hdr *ershdr, u16 id)
+{
+	ershdr->session_id = id & 0xff;
+	ershdr->session_id_upper = (id >> 8) & 0x3;
+}
+
+static inline u16 get_session_id(const struct erspan_base_hdr *ershdr)
+{
+	return (ershdr->session_id_upper << 8) + ershdr->session_id;
+}
+
+static inline void set_vlan(struct erspan_base_hdr *ershdr, u16 vlan)
+{
+	ershdr->vlan = vlan & 0xff;
+	ershdr->vlan_upper = (vlan >> 8) & 0xf;
+}
+
+static inline u16 get_vlan(const struct erspan_base_hdr *ershdr)
+{
+	return (ershdr->vlan_upper << 8) + ershdr->vlan;
+}
+
+static inline void set_hwid(struct erspan_md2 *md2, u8 hwid)
+{
+	md2->hwid = hwid & 0xf;
+	md2->hwid_upper = (hwid >> 4) & 0x3;
+}
+
+static inline u8 get_hwid(const struct erspan_md2 *md2)
+{
+	return (md2->hwid_upper << 4) + md2->hwid;
+}
 
 static inline int erspan_hdr_len(int version)
 {
···
 }
 
 static inline void erspan_build_header(struct sk_buff *skb,
-				__be32 id, u32 index,
+				u32 id, u32 index,
 				bool truncate, bool is_ipv4)
 {
 	struct ethhdr *eth = (struct ethhdr *)skb->data;
···
 	memset(ershdr, 0, sizeof(*ershdr) + ERSPAN_V1_MDSIZE);
 
 	/* Build base header */
-	ershdr->ver_vlan = htons((vlan_tci & VLAN_MASK) |
-				 (ERSPAN_VERSION << VER_OFFSET));
-	ershdr->session_id = htons((u16)(ntohl(id) & ID_MASK) |
-			   ((tos_to_cos(tos) << COS_OFFSET) & COS_MASK) |
-			   (enc_type << EN_OFFSET & EN_MASK) |
-			   ((truncate << T_OFFSET) & T_MASK));
+	ershdr->ver = ERSPAN_VERSION;
+	ershdr->cos = tos_to_cos(tos);
+	ershdr->en = enc_type;
+	ershdr->t = truncate;
+	set_vlan(ershdr, vlan_tci);
+	set_session_id(ershdr, id);
 
 	/* Build metadata */
 	ersmd = (struct erspan_metadata *)(ershdr + 1);
···
 }
 
 static inline void erspan_build_header_v2(struct sk_buff *skb,
-					  __be32 id, u8 direction, u16 hwid,
+					  u32 id, u8 direction, u16 hwid,
 					  bool truncate, bool is_ipv4)
 {
 	struct ethhdr *eth = (struct ethhdr *)skb->data;
···
 		__be16 tci;
 	} *qp;
 	u16 vlan_tci = 0;
-	u16 session_id;
 	u8 gra = 0; /* 100 usec */
 	u8 bso = 0; /* Bad/Short/Oversized */
 	u8 sgt = 0;
···
 	memset(ershdr, 0, sizeof(*ershdr) + ERSPAN_V2_MDSIZE);
 
 	/* Build base header */
-	ershdr->ver_vlan = htons((vlan_tci & VLAN_MASK) |
-				 (ERSPAN_VERSION2 << VER_OFFSET));
-	session_id = (u16)(ntohl(id) & ID_MASK) |
-		     ((tos_to_cos(tos) << COS_OFFSET) & COS_MASK) |
-		     (bso << BSO_OFFSET & BSO_MASK) |
-		     ((truncate << T_OFFSET) & T_MASK);
-	ershdr->session_id = htons(session_id);
+	ershdr->ver = ERSPAN_VERSION2;
+	ershdr->cos = tos_to_cos(tos);
+	ershdr->en = bso;
+	ershdr->t = truncate;
+	set_vlan(ershdr, vlan_tci);
+	set_session_id(ershdr, id);
 
 	/* Build metadata */
 	md = (struct erspan_metadata *)(ershdr + 1);
 	md->u.md2.timestamp = erspan_get_timestamp();
 	md->u.md2.sgt = htons(sgt);
-	md->u.md2.flags = htons(((1 << P_OFFSET) & P_MASK) |
-				((hwid << HWID_OFFSET) & HWID_MASK) |
-				((direction << DIR_OFFSET) & DIR_MASK) |
-				((gra << GRA_OFFSET) & GRA_MASK));
+	md->u.md2.p = 1;
+	md->u.md2.ft = 0;
+	md->u.md2.dir = direction;
+	md->u.md2.gra = gra;
+	md->u.md2.o = 0;
+	set_hwid(&md->u.md2, hwid);
 }
 
 #endif

net/ipv4/ip_gre.c

···
 static struct rtnl_link_ops ipgre_link_ops __read_mostly;
 static int ipgre_tunnel_init(struct net_device *dev);
 static void erspan_build_header(struct sk_buff *skb,
-				__be32 id, u32 index,
+				u32 id, u32 index,
 				bool truncate, bool is_ipv4);
 
 static unsigned int ipgre_net_id __read_mostly;
···
 
 	iph = ip_hdr(skb);
 	ershdr = (struct erspan_base_hdr *)(skb->data + gre_hdr_len);
-	ver = (ntohs(ershdr->ver_vlan) & VER_MASK) >> VER_OFFSET;
+	ver = ershdr->ver;
 
 	/* The original GRE header does not have key field,
 	 * Use ERSPAN 10-bit session ID as key.
 	 */
-	tpi->key = cpu_to_be32(ntohs(ershdr->session_id) & ID_MASK);
+	tpi->key = cpu_to_be32(get_session_id(ershdr));
 	tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex,
 				  tpi->flags | TUNNEL_KEY,
 				  iph->saddr, iph->daddr, tpi->key);
···
 			if (ver == 1) {
 				tunnel->index = ntohl(pkt_md->u.index);
 			} else {
-				u16 md2_flags;
-				u16 dir, hwid;
-
-				md2_flags = ntohs(pkt_md->u.md2.flags);
-				dir = (md2_flags & DIR_MASK) >> DIR_OFFSET;
-				hwid = (md2_flags & HWID_MASK) >> HWID_OFFSET;
-				tunnel->dir = dir;
-				tunnel->hwid = hwid;
+				tunnel->dir = pkt_md->u.md2.dir;
+				tunnel->hwid = get_hwid(&pkt_md->u.md2);
 			}
 
 		}
···
 	}
 
 	if (version == 1) {
-		erspan_build_header(skb, tunnel_id_to_key32(key->tun_id),
+		erspan_build_header(skb, ntohl(tunnel_id_to_key32(key->tun_id)),
 				    ntohl(md->u.index), truncate, true);
 	} else if (version == 2) {
-		u16 md2_flags;
-		u8 direction;
-		u16 hwid;
-
-		md2_flags = ntohs(md->u.md2.flags);
-		direction = (md2_flags & DIR_MASK) >> DIR_OFFSET;
-		hwid = (md2_flags & HWID_MASK) >> HWID_OFFSET;
-
-		erspan_build_header_v2(skb, tunnel_id_to_key32(key->tun_id),
-				       direction, hwid,	truncate, true);
+		erspan_build_header_v2(skb,
+				       ntohl(tunnel_id_to_key32(key->tun_id)),
+				       md->u.md2.dir,
+				       get_hwid(&md->u.md2),
+				       truncate, true);
 	} else {
 		goto err_free_rt;
 	}
···
 
 	/* Push ERSPAN header */
 	if (tunnel->erspan_ver == 1)
-		erspan_build_header(skb, tunnel->parms.o_key, tunnel->index,
+		erspan_build_header(skb, ntohl(tunnel->parms.o_key),
+				    tunnel->index,
 				    truncate, true);
 	else
-		erspan_build_header_v2(skb, tunnel->parms.o_key,
+		erspan_build_header_v2(skb, ntohl(tunnel->parms.o_key),
 				       tunnel->dir, tunnel->hwid,
 				       truncate, true);
 

net/ipv6/ip6_gre.c

···
 
 	ipv6h = ipv6_hdr(skb);
 	ershdr = (struct erspan_base_hdr *)skb->data;
-	ver = (ntohs(ershdr->ver_vlan) & VER_MASK) >> VER_OFFSET;
-	tpi->key = cpu_to_be32(ntohs(ershdr->session_id) & ID_MASK);
+	ver = ershdr->ver;
+	tpi->key = cpu_to_be32(get_session_id(ershdr));
 
 	tunnel = ip6gre_tunnel_lookup(skb->dev,
 				      &ipv6h->saddr, &ipv6h->daddr, tpi->key,
···
 			if (ver == 1) {
 				tunnel->parms.index = ntohl(pkt_md->u.index);
 			} else {
-				u16 md2_flags;
-				u16 dir, hwid;
-
-				md2_flags = ntohs(pkt_md->u.md2.flags);
-				dir = (md2_flags & DIR_MASK) >> DIR_OFFSET;
-				hwid = (md2_flags & HWID_MASK) >> HWID_OFFSET;
-				tunnel->parms.dir = dir;
-				tunnel->parms.hwid = hwid;
+				tunnel->parms.dir = pkt_md->u.md2.dir;
+				tunnel->parms.hwid = get_hwid(&pkt_md->u.md2);
 			}
 
 			ip6_tnl_rcv(tunnel, skb, tpi, NULL, log_ecn_error);
···
 		struct ip_tunnel_info *tun_info;
 		const struct ip_tunnel_key *key;
 		struct erspan_metadata *md;
+		__be32 tun_id;
 
 		tun_info = skb_tunnel_info(skb);
 		if (unlikely(!tun_info ||
···
 		if (!md)
 			goto tx_err;
 
+		tun_id = tunnel_id_to_key32(key->tun_id);
 		if (md->version == 1) {
 			erspan_build_header(skb,
-					    tunnel_id_to_key32(key->tun_id),
+					    ntohl(tun_id),
 					    ntohl(md->u.index), truncate,
 					    false);
 		} else if (md->version == 2) {
-			u16 md2_flags;
-			u16 dir, hwid;
-
-			md2_flags = ntohs(md->u.md2.flags);
-			dir = (md2_flags & DIR_MASK) >> DIR_OFFSET;
-			hwid = (md2_flags & HWID_MASK) >> HWID_OFFSET;
-
 			erspan_build_header_v2(skb,
-					       tunnel_id_to_key32(key->tun_id),
-					       dir, hwid, truncate,
-					       false);
+					       ntohl(tun_id),
+					       md->u.md2.dir,
+					       get_hwid(&md->u.md2),
+					       truncate, false);
 		}
 	} else {
 		switch (skb->protocol) {
···
 		}
 
 		if (t->parms.erspan_ver == 1)
-			erspan_build_header(skb, t->parms.o_key,
+			erspan_build_header(skb, ntohl(t->parms.o_key),
 					    t->parms.index,
 					    truncate, false);
 		else
-			erspan_build_header_v2(skb, t->parms.o_key,
+			erspan_build_header_v2(skb, ntohl(t->parms.o_key),
 					       t->parms.dir,
 					       t->parms.hwid,
 					       truncate, false);