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 <u9012063@gmail.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 121 insertions, 80 deletions

diff --git a/include/net/erspan.h b/include/net/erspan.h
index 712ea1b1f4db..6d30fe898286 100644
--- a/include/net/erspan.h
+++ b/include/net/erspan.h
@@ -65,16 +65,30 @@
 #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 {
@@ -95,15 +109,62 @@ struct erspan_metadata {
 };
 
 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)
 {
         return sizeof(struct erspan_base_hdr) +
@@ -120,7 +181,7 @@ static inline u8 tos_to_cos(u8 tos)
 }
 
 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;
@@ -154,12 +215,12 @@ static inline void erspan_build_header(struct sk_buff *skb,
         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);
@@ -187,7 +248,7 @@ static inline __be32 erspan_get_timestamp(void)
 }
 
 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;
@@ -198,7 +259,6 @@ static inline void erspan_build_header_v2(struct sk_buff *skb,
                 __be16 tci;
         } *qp;
         u16 vlan_tci = 0;
-        u16 session_id;
         u8 gra = 0; /* 100 usec */
         u8 bso = 0; /* Bad/Short/Oversized */
         u8 sgt = 0;
@@ -221,22 +281,23 @@ static inline void erspan_build_header_v2(struct sk_buff *skb,
         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
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index b61f2285816d..6ec670fbbbdd 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -114,7 +114,7 @@ MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
 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;
@@ -273,12 +273,12 @@ static int erspan_rcv(struct sk_buff *skb, struct tnl_ptk_info *tpi,
 
         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);
@@ -324,14 +324,8 @@ static int erspan_rcv(struct sk_buff *skb, struct tnl_ptk_info *tpi,
                         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);
                         }
 
                 }
@@ -615,19 +609,14 @@ static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev,
         }
 
         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;
         }
@@ -733,10 +722,11 @@ static netdev_tx_t erspan_xmit(struct sk_buff *skb,
 
         /* 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);
 
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index a88480193d77..05f070e123e4 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -513,8 +513,8 @@ static int ip6erspan_rcv(struct sk_buff *skb, int gre_hdr_len,
 
         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,
@@ -565,14 +565,8 @@ static int ip6erspan_rcv(struct sk_buff *skb, int gre_hdr_len,
                         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);
@@ -925,6 +919,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
                 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 ||
@@ -944,23 +939,18 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
                 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) {
@@ -982,11 +972,11 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
                 }
 
                 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);