xnu-4903.221.2.tar.gz

[apple/xnu.git] / bsd / netinet / in_cksum.c

diff --git a/bsd/netinet/in_cksum.c b/bsd/netinet/in_cksum.c
index 850273c86516f63b09bfdb28a1aefafa594d788d..538794d8dd2f3f1ff82e25d78e4ee8a65504402c 100644 (file)
--- a/bsd/netinet/in_cksum.c
+++ b/bsd/netinet/in_cksum.c
@@ -1,16 +1,19 @@
 /*
 /*

- * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2000-2017 Apple Inc. All rights reserved.

  *
  *

- * @APPLE_LICENSE_HEADER_START@
- * 
- * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@

  * 
  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in
  * 
  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in

- * compliance with the License. Please obtain a copy of the License at
- * http://www.opensource.apple.com/apsl/ and read it before using this
- * file.
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ * 
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.

  * 
  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * 
  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER


@@ -20,7 +23,7 @@
  * Please see the License for the specific language governing rights and
  * limitations under the License.
  * 
  * Please see the License for the specific language governing rights and
  * limitations under the License.
  * 

- * @APPLE_LICENSE_HEADER_END@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@

  */
 /*
  * Copyright (c) 1988, 1992, 1993
  */
 /*
  * Copyright (c) 1988, 1992, 1993


@@ -58,10 +61,14 @@
  */
 
 #include <sys/param.h>
  */
 
 #include <sys/param.h>

+#include <machine/endian.h>

 #include <sys/mbuf.h>
 #include <sys/mbuf.h>

-#include <sys/kdebug.h>
-
-#define DBG_FNC_IN_CKSUM       NETDBG_CODE(DBG_NETIP, (3 << 8))
+#include <kern/debug.h>
+#include <net/dlil.h>
+#include <netinet/in.h>
+#define        _IP_VHL
+#include <netinet/ip.h>
+#include <netinet/ip_var.h>

 
 /*
  * Checksum routine for Internet Protocol family headers (Portable Version).
 
 /*
  * Checksum routine for Internet Protocol family headers (Portable Version).


@@ -69,378 +76,550 @@
  * This routine is very heavily used in the network
  * code and should be modified for each CPU to be as fast as possible.
  */
  * This routine is very heavily used in the network
  * code and should be modified for each CPU to be as fast as possible.
  */

-
-union s_util {
-        char    c[2];
-        u_short s;
-};
+#define REDUCE16 {                                                       \
+       q_util.q = sum;                                                   \
+       l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
+       sum = l_util.s[0] + l_util.s[1];                                  \
+       ADDCARRY(sum);                                                    \
+}

 
 union l_util {
 
 union l_util {

-        u_int16_t s[2];
-        u_int32_t l;   
+        uint16_t s[2];
+        uint32_t l;

 };
 
 union q_util {
 };
 
 union q_util {

-        u_int16_t s[4];
-        u_int32_t l[2];
-        u_int64_t q;
-};    
-
-#define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
-
-#define REDUCE32                                                          \
-    {                                                                     \
-        q_util.q = sum;                                                   \
-        sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3];      \
-    }
-#define REDUCE16                                                          \
-    {                                                                     \
-        q_util.q = sum;                                                   \
-        l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
-        sum = l_util.s[0] + l_util.s[1];                                  \
-        ADDCARRY(sum);                                                    \
-    }
-
-#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
-
-                
-#if defined(ppc)
-
-__inline unsigned short
-in_addword(u_short a, u_short b)
+        uint16_t s[4];
+        uint32_t l[2];
+        uint64_t q;
+};
+
+extern uint32_t os_cpu_in_cksum(const void *, uint32_t, uint32_t);
+
+/*
+ * Perform 16-bit 1's complement sum on a contiguous span.
+ */
+uint16_t
+b_sum16(const void *buf, int len)
+{
+       return (os_cpu_in_cksum(buf, len, 0));
+}
+
+uint16_t inet_cksum_simple(struct mbuf *, int);
+/*
+ * For the exported _in_cksum symbol in BSDKernel symbol set.
+ */
+uint16_t
+inet_cksum_simple(struct mbuf *m, int len)

 {
 {

-        union l_util l_util;   
-       u_int32_t sum = a + b;
-       REDUCE;
+       return (inet_cksum(m, 0, 0, len));
+}
+
+uint16_t
+in_addword(uint16_t a, uint16_t b)
+{
+       uint64_t sum = a + b;
+
+       ADDCARRY(sum);

        return (sum);
 }
 
        return (sum);
 }
 

-__inline unsigned short
-in_pseudo(u_int a, u_int b, u_int c)
+uint16_t
+in_pseudo(uint32_t a, uint32_t b, uint32_t c)

 {
 {

-        u_int64_t sum;
+        uint64_t sum;

         union q_util q_util;
         union q_util q_util;

-        union l_util l_util;   
+        union l_util l_util;

 
 

-        sum = (u_int64_t) a + b + c;
+        sum = (uint64_t)a + b + c;

         REDUCE16;
         return (sum);
         REDUCE16;
         return (sum);

-

 }
 
 }
 

-int
-in_cksum(m, len)
-       register struct mbuf *m;
-       register int len;
+uint16_t
+in_pseudo64(uint64_t a, uint64_t b, uint64_t c)

 {
 {

-       register u_short *w;
-       register int sum = 0;
-       register int mlen = 0;
-       int starting_on_odd  = 0;
+       uint64_t sum;
+       union q_util q_util;
+       union l_util l_util;

 
 

+       sum = a + b + c;
+       REDUCE16;
+       return (sum);
+}

 
 

-       KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_START, len,0,0,0,0);
+/*
+ * May be used on IP header with options.
+ */
+uint16_t
+in_cksum_hdr_opt(const struct ip *ip)
+{
+       return (~b_sum16(ip, (IP_VHL_HL(ip->ip_vhl) << 2)) & 0xffff);
+}

 
 

-       for (;m && len; m = m->m_next) {
-               if (m->m_len == 0)
-                       continue;
-               mlen = m->m_len;
-               w = mtod(m, u_short *);
+/*
+ * A wrapper around the simple in_cksum_hdr() and the more complicated
+ * inet_cksum(); the former is chosen if the IP header is simple,
+ * contiguous and 32-bit aligned.  Also does some stats accounting.
+ */
+uint16_t
+ip_cksum_hdr_dir(struct mbuf *m, uint32_t hlen, int out)
+{
+       struct ip *ip = mtod(m, struct ip *);
+
+       if (out) {
+               ipstat.ips_snd_swcsum++;
+               ipstat.ips_snd_swcsum_bytes += hlen;
+       } else {
+               ipstat.ips_rcv_swcsum++;
+               ipstat.ips_rcv_swcsum_bytes += hlen;
+       }

 
 

-               if (len < mlen)
-                       mlen = len;
+       if (hlen == sizeof (*ip) &&
+           m->m_len >= sizeof (*ip) && IP_HDR_ALIGNED_P(ip))
+               return (in_cksum_hdr(ip));

 
 

-               sum = xsum_assym(w, mlen, sum, starting_on_odd);
-               len -= mlen;
-               if (mlen & 0x1)
-               {
-                   if (starting_on_odd)
-                       starting_on_odd = 0;
-                   else
-                       starting_on_odd = 1;
-               }
+       return (inet_cksum(m, 0, 0, hlen));
+}
+
+uint16_t
+ip_cksum_hdr_dir_buffer(const void *buffer, uint32_t hlen, uint32_t len,
+    int out)
+{
+       const struct ip *ip = buffer;
+
+       if (out) {
+               ipstat.ips_snd_swcsum++;
+               ipstat.ips_snd_swcsum_bytes += hlen;
+       } else {
+               ipstat.ips_rcv_swcsum++;
+               ipstat.ips_rcv_swcsum_bytes += hlen;

        }
 
        }
 

-       KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_END, 0,0,0,0,0);
-       return (~sum & 0xffff);
+       if (hlen == sizeof (*ip) &&
+           len >= sizeof (*ip) && IP_HDR_ALIGNED_P(ip))
+               return (in_cksum_hdr(ip));
+
+       return (inet_cksum_buffer(buffer, 0, 0, hlen));

 }
 
 }
 

-u_short
-in_cksum_skip(m, len, skip)
-        register struct mbuf *m;
-        register int len;
-        register int skip;
+/*
+ * m MUST contain at least an IP header, if nxt is specified;
+ * nxt is the upper layer protocol number;
+ * off is an offset where TCP/UDP/ICMP header starts;
+ * len is a total length of a transport segment (e.g. TCP header + TCP payload)
+ */
+uint16_t
+inet_cksum(struct mbuf *m, uint32_t nxt, uint32_t off, uint32_t len)

 {
 {

-       register u_short *w;
-       register int sum = 0;
-       register int mlen = 0;
-       int starting_on_odd  = 0;
-
-       len -= skip;
-        for (; skip && m; m = m->m_next) {
-                if (m->m_len > skip) {
-                        mlen = m->m_len - skip;
-                       w = (u_short *)(m->m_data+skip);
-                        goto skip_start;
-                } else {    
-                        skip -= m->m_len;
-                }
-        }
-       for (;m && len; m = m->m_next) {
-               if (m->m_len == 0)
-                       continue;
-               mlen = m->m_len;
-               w = mtod(m, u_short *);
+       uint32_t sum;

 
 

-skip_start:
-               if (len < mlen)
-                       mlen = len;
-               sum = xsum_assym(w, mlen, sum, starting_on_odd);
-               len -= mlen;
-               if (mlen & 0x1)
-               {
-                   if (starting_on_odd)
-                       starting_on_odd = 0;
-                   else
-                       starting_on_odd = 1;
+       sum = m_sum16(m, off, len);
+
+       /* include pseudo header checksum? */
+       if (nxt != 0) {
+               struct ip *ip;
+               unsigned char buf[sizeof ((*ip))] __attribute__((aligned(8)));
+               uint32_t mlen;
+
+               /*
+                * Sanity check
+                *
+                * Use m_length2() instead of m_length(), as we cannot rely on
+                * the caller setting m_pkthdr.len correctly, if the mbuf is
+                * a M_PKTHDR one.
+                */
+               if ((mlen = m_length2(m, NULL)) < sizeof (*ip)) {
+                       panic("%s: mbuf %p too short (%d) for IPv4 header",
+                           __func__, m, mlen);
+                       /* NOTREACHED */

                }
                }

+
+               /*
+                * In case the IP header is not contiguous, or not 32-bit
+                * aligned, copy it to a local buffer.  Note here that we
+                * expect the data pointer to point to the IP header.
+                */
+               if ((sizeof (*ip) > m->m_len) ||
+                   !IP_HDR_ALIGNED_P(mtod(m, caddr_t))) {
+                       m_copydata(m, 0, sizeof (*ip), (caddr_t)buf);
+                       ip = (struct ip *)(void *)buf;
+               } else {
+                       ip = (struct ip *)(void *)(m->m_data);
+               }
+
+               /* add pseudo header checksum */
+               sum += in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
+                   htonl(len + nxt));
+
+               /* fold in carry bits */
+               ADDCARRY(sum);

        }
 
        return (~sum & 0xffff);
 }
        }
 
        return (~sum & 0xffff);
 }

-#else
-
-u_short 
-in_addword(u_short a, u_short b)
-{       
-        union l_util l_util;   
-        u_int32_t sum = a + b;
-        REDUCE(sum);
-        return (sum);
-}       

 
 

-u_short
-in_pseudo(u_int a, u_int b, u_int c)
+/*
+ * buffer MUST contain at least an IP header, if nxt is specified;
+ * nxt is the upper layer protocol number;
+ * off is an offset where TCP/UDP/ICMP header starts;
+ * len is a total length of a transport segment (e.g. TCP header + TCP payload)
+ */
+uint16_t
+inet_cksum_buffer(const void *buffer, uint32_t nxt, uint32_t off,
+    uint32_t len)

 {
 {

-        u_int64_t sum;  
-        union q_util q_util;
-        union l_util l_util;   
+       uint32_t sum;

 
 

-        sum = (u_int64_t) a + b + c;
-        REDUCE16;
-        return (sum);
+       if (off >= len)
+               panic("%s: off (%d) >= len (%d)", __func__, off, len);
+
+       sum = b_sum16(&((const uint8_t *)buffer)[off], len);
+
+       /* include pseudo header checksum? */
+       if (nxt != 0) {
+               const struct ip *ip;
+               unsigned char buf[sizeof ((*ip))] __attribute__((aligned(8)));
+
+               /*
+                * In case the IP header is not contiguous, or not 32-bit
+                * aligned, copy it to a local buffer.  Note here that we
+                * expect the data pointer to point to the IP header.
+                */
+               if (!IP_HDR_ALIGNED_P(buffer)) {
+                       memcpy(buf, buffer, sizeof (*ip));
+                       ip = (const struct ip *)(const void *)buf;
+               } else {
+                       ip = (const struct ip *)buffer;
+               }
+
+               /* add pseudo header checksum */
+               sum += in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
+                   htonl(len + nxt));
+
+               /* fold in carry bits */
+               ADDCARRY(sum);
+       }
+
+       return (~sum & 0xffff);

 }
 
 }
 

+#if DEBUG || DEVELOPMENT
+#include <pexpert/pexpert.h>

 
 

-int
-in_cksum(m, len)
-       register struct mbuf *m;
-       register int len;
-{
-       register u_short *w;
-       register int sum = 0;
-       register int mlen = 0;
-       int byte_swapped = 0;
-       union s_util s_util;
-       union l_util l_util;   
+#define        CKSUM_ERR kprintf

 
 

-       KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_START, len,0,0,0,0);
+/*
+ * The following routines implement the portable, reference implementation
+ * of os_cpu_in_cksum_mbuf().  This is currently used only for validating
+ * the correctness of the platform-specific implementation, at boot time
+ * in dlil_verify_sum16().  It returns the 32-bit accumulator without doing
+ * a 1's complement on it.
+ */
+#if !defined(__LP64__)
+/* 32-bit version */
+uint32_t
+in_cksum_mbuf_ref(struct mbuf *m, int len, int off, uint32_t initial_sum)
+{
+       int mlen;
+       uint32_t sum, partial;
+       unsigned int final_acc;
+       uint8_t *data;
+       boolean_t needs_swap, started_on_odd;
+
+       VERIFY(len >= 0);
+       VERIFY(off >= 0);
+
+       needs_swap = FALSE;
+       started_on_odd = FALSE;
+       sum = (initial_sum >> 16) + (initial_sum & 0xffff);
+
+       for (;;) {
+               if (__improbable(m == NULL)) {
+                       CKSUM_ERR("%s: out of data\n", __func__);
+                       return ((uint32_t)-1);
+               }
+               mlen = m->m_len;
+               if (mlen > off) {
+                       mlen -= off;
+                       data = mtod(m, uint8_t *) + off;
+                       goto post_initial_offset;
+               }
+               off -= mlen;
+               if (len == 0)
+                       break;
+               m = m->m_next;
+       }

 
 

-       for (;m && len; m = m->m_next) {
-               if (m->m_len == 0)
+       for (; len > 0; m = m->m_next) {
+               if (__improbable(m == NULL)) {
+                       CKSUM_ERR("%s: out of data\n", __func__);
+                       return ((uint32_t)-1);
+               }
+               mlen = m->m_len;
+               data = mtod(m, uint8_t *);
+post_initial_offset:
+               if (mlen == 0)

                        continue;
                        continue;

-               w = mtod(m, u_short *);
-               if (mlen == -1) {
-                       /*
-                        * The first byte of this mbuf is the continuation
-                        * of a word spanning between this mbuf and the
-                        * last mbuf.
-                        *
-                        * s_util.c[0] is already saved when scanning previous
-                        * mbuf.
-                        */
-                       s_util.c[1] = *(char *)w;
-                       sum += s_util.s;
-                       w = (u_short *)((char *)w + 1);
-                       mlen = m->m_len - 1;
-                       len--;
-               } else
-                       mlen = m->m_len;
-               if (len < mlen)
+               if (mlen > len)

                        mlen = len;
                len -= mlen;
                        mlen = len;
                len -= mlen;

-               /*
-                * Force to even boundary.
-                */
-               if ((1 & (int) w) && (mlen > 0)) {
-                       REDUCE;
-                       sum <<= 8;
-                       s_util.c[0] = *(u_char *)w;
-                       w = (u_short *)((char *)w + 1);
-                       mlen--;
-                       byte_swapped = 1;
+
+               partial = 0;
+               if ((uintptr_t)data & 1) {
+                       /* Align on word boundary */
+                       started_on_odd = !started_on_odd;
+#if BYTE_ORDER == LITTLE_ENDIAN
+                       partial = *data << 8;
+#else /* BYTE_ORDER != LITTLE_ENDIAN */
+                       partial = *data;
+#endif /* BYTE_ORDER != LITTLE_ENDIAN */
+                       ++data;
+                       --mlen;
+               }
+               needs_swap = started_on_odd;
+               while (mlen >= 32) {
+                       __builtin_prefetch(data + 32);
+                       partial += *(uint16_t *)(void *)data;
+                       partial += *(uint16_t *)(void *)(data + 2);
+                       partial += *(uint16_t *)(void *)(data + 4);
+                       partial += *(uint16_t *)(void *)(data + 6);
+                       partial += *(uint16_t *)(void *)(data + 8);
+                       partial += *(uint16_t *)(void *)(data + 10);
+                       partial += *(uint16_t *)(void *)(data + 12);
+                       partial += *(uint16_t *)(void *)(data + 14);
+                       partial += *(uint16_t *)(void *)(data + 16);
+                       partial += *(uint16_t *)(void *)(data + 18);
+                       partial += *(uint16_t *)(void *)(data + 20);
+                       partial += *(uint16_t *)(void *)(data + 22);
+                       partial += *(uint16_t *)(void *)(data + 24);
+                       partial += *(uint16_t *)(void *)(data + 26);
+                       partial += *(uint16_t *)(void *)(data + 28);
+                       partial += *(uint16_t *)(void *)(data + 30);
+                       data += 32;
+                       mlen -= 32;
+                       if (__improbable(partial & 0xc0000000)) {
+                               if (needs_swap)
+                                       partial = (partial << 8) +
+                                           (partial >> 24);
+                               sum += (partial >> 16);
+                               sum += (partial & 0xffff);
+                               partial = 0;
+                       }
+               }
+               if (mlen & 16) {
+                       partial += *(uint16_t *)(void *)data;
+                       partial += *(uint16_t *)(void *)(data + 2);
+                       partial += *(uint16_t *)(void *)(data + 4);
+                       partial += *(uint16_t *)(void *)(data + 6);
+                       partial += *(uint16_t *)(void *)(data + 8);
+                       partial += *(uint16_t *)(void *)(data + 10);
+                       partial += *(uint16_t *)(void *)(data + 12);
+                       partial += *(uint16_t *)(void *)(data + 14);
+                       data += 16;
+                       mlen -= 16;

                }
                /*
                }
                /*

-                * Unroll the loop to make overhead from
-                * branches &c small.
+                * mlen is not updated below as the remaining tests
+                * are using bit masks, which are not affected.

                 */
                 */

-               while ((mlen -= 32) >= 0) {
-                       sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
-                       sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
-                       sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
-                       sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
-                       w += 16;
+               if (mlen & 8) {
+                       partial += *(uint16_t *)(void *)data;
+                       partial += *(uint16_t *)(void *)(data + 2);
+                       partial += *(uint16_t *)(void *)(data + 4);
+                       partial += *(uint16_t *)(void *)(data + 6);
+                       data += 8;

                }
                }

-               mlen += 32;
-               while ((mlen -= 8) >= 0) {
-                       sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
-                       w += 4;
+               if (mlen & 4) {
+                       partial += *(uint16_t *)(void *)data;
+                       partial += *(uint16_t *)(void *)(data + 2);
+                       data += 4;

                }
                }

-               mlen += 8;
-               if (mlen == 0 && byte_swapped == 0)
-                       continue;
-               REDUCE;
-               while ((mlen -= 2) >= 0) {
-                       sum += *w++;
+               if (mlen & 2) {
+                       partial += *(uint16_t *)(void *)data;
+                       data += 2;

                }
                }

-               if (byte_swapped) {
-                       REDUCE;
-                       sum <<= 8;
-                       byte_swapped = 0;
-                       if (mlen == -1) {
-                               s_util.c[1] = *(char *)w;
-                               sum += s_util.s;
-                               mlen = 0;
-                       } else
-                               mlen = -1;
-               } else if (mlen == -1)
-                       s_util.c[0] = *(char *)w;
-       }
-       if (len)
-               printf("cksum: out of data\n");
-       if (mlen == -1) {
-               /* The last mbuf has odd # of bytes. Follow the
-                  standard (the odd byte may be shifted left by 8 bits
-                  or not as determined by endian-ness of the machine) */
-               s_util.c[1] = 0;
-               sum += s_util.s;
+               if (mlen & 1) {
+#if BYTE_ORDER == LITTLE_ENDIAN
+                       partial += *data;
+#else /* BYTE_ORDER != LITTLE_ENDIAN */
+                       partial += *data << 8;
+#endif /* BYTE_ORDER != LITTLE_ENDIAN */
+                       started_on_odd = !started_on_odd;
+               }
+
+               if (needs_swap)
+                       partial = (partial << 8) + (partial >> 24);
+               sum += (partial >> 16) + (partial & 0xffff);
+               /*
+                * Reduce sum to allow potential byte swap
+                * in the next iteration without carry.
+                */
+               sum = (sum >> 16) + (sum & 0xffff);

        }
        }

-       REDUCE;
-       KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_END, 0,0,0,0,0);
-       return (~sum & 0xffff);
+       final_acc = ((sum >> 16) & 0xffff) + (sum & 0xffff);
+       final_acc = (final_acc >> 16) + (final_acc & 0xffff);
+       return (final_acc & 0xffff);

 }
 
 }
 

-int
-in_cksum_skip(m, len, skip)
-       register struct mbuf *m;
-       register u_short len;
-       register u_short skip;
+#else /* __LP64__ */
+/* 64-bit version */
+uint32_t
+in_cksum_mbuf_ref(struct mbuf *m, int len, int off, uint32_t initial_sum)

 {
 {

-       register u_short *w;
-       register int sum = 0;
-       register int mlen = 0;
-       int byte_swapped = 0;
-       union s_util s_util;
-       union l_util l_util;   
-
-       KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_START, len,0,0,0,0);
-
-       len -= skip;
-        for (; skip && m; m = m->m_next) {
-                if (m->m_len > skip) {
-                        mlen = m->m_len - skip;
-                       w = (u_short *)(m->m_data+skip);
-                        goto skip_start;
-                } else {    
-                        skip -= m->m_len;
-                }
-        }
-       for (;m && len; m = m->m_next) {
-               if (m->m_len == 0)
-                       continue;
-               w = mtod(m, u_short *);
-
-               if (mlen == -1) {
-                       /*
-                        * The first byte of this mbuf is the continuation
-                        * of a word spanning between this mbuf and the
-                        * last mbuf.
-                        *
-                        * s_util.c[0] is already saved when scanning previous
-                        * mbuf.
-                        */
-                       s_util.c[1] = *(char *)w;
-                       sum += s_util.s;
-                       w = (u_short *)((char *)w + 1);
-                       mlen = m->m_len - 1;
-                       len--;
-               } else {
-                 mlen = m->m_len;
+       int mlen;
+       uint64_t sum, partial;
+       unsigned int final_acc;
+       uint8_t *data;
+       boolean_t needs_swap, started_on_odd;
+
+       VERIFY(len >= 0);
+       VERIFY(off >= 0);
+
+       needs_swap = FALSE;
+       started_on_odd = FALSE;
+       sum = initial_sum;
+
+       for (;;) {
+               if (__improbable(m == NULL)) {
+                       CKSUM_ERR("%s: out of data\n", __func__);
+                       return ((uint32_t)-1);

                }
                }

-skip_start:
-               if (len < mlen)
-                   mlen = len;
+               mlen = m->m_len;
+               if (mlen > off) {
+                       mlen -= off;
+                       data = mtod(m, uint8_t *) + off;
+                       goto post_initial_offset;
+               }
+               off -= mlen;
+               if (len == 0)
+                       break;
+               m = m->m_next;
+       }

 
 

+       for (; len > 0; m = m->m_next) {
+               if (__improbable(m == NULL)) {
+                       CKSUM_ERR("%s: out of data\n", __func__);
+                       return ((uint32_t)-1);
+               }
+               mlen = m->m_len;
+               data = mtod(m, uint8_t *);
+post_initial_offset:
+               if (mlen == 0)
+                       continue;
+               if (mlen > len)
+                       mlen = len;

                len -= mlen;
                len -= mlen;

-               /*
-                * Force to even boundary.
-                */
-               if ((1 & (int) w) && (mlen > 0)) {
-                       REDUCE;
-                       sum <<= 8;
-                       s_util.c[0] = *(u_char *)w;
-                       w = (u_short *)((char *)w + 1);
-                       mlen--;
-                       byte_swapped = 1;
+
+               partial = 0;
+               if ((uintptr_t)data & 1) {
+                       /* Align on word boundary */
+                       started_on_odd = !started_on_odd;
+#if BYTE_ORDER == LITTLE_ENDIAN
+                       partial = *data << 8;
+#else /* BYTE_ORDER != LITTLE_ENDIAN */
+                       partial = *data;
+#endif /* BYTE_ORDER != LITTLE_ENDIAN */
+                       ++data;
+                       --mlen;
+               }
+               needs_swap = started_on_odd;
+               if ((uintptr_t)data & 2) {
+                       if (mlen < 2)
+                               goto trailing_bytes;
+                       partial += *(uint16_t *)(void *)data;
+                       data += 2;
+                       mlen -= 2;
+               }
+               while (mlen >= 64) {
+                       __builtin_prefetch(data + 32);
+                       __builtin_prefetch(data + 64);
+                       partial += *(uint32_t *)(void *)data;
+                       partial += *(uint32_t *)(void *)(data + 4);
+                       partial += *(uint32_t *)(void *)(data + 8);
+                       partial += *(uint32_t *)(void *)(data + 12);
+                       partial += *(uint32_t *)(void *)(data + 16);
+                       partial += *(uint32_t *)(void *)(data + 20);
+                       partial += *(uint32_t *)(void *)(data + 24);
+                       partial += *(uint32_t *)(void *)(data + 28);
+                       partial += *(uint32_t *)(void *)(data + 32);
+                       partial += *(uint32_t *)(void *)(data + 36);
+                       partial += *(uint32_t *)(void *)(data + 40);
+                       partial += *(uint32_t *)(void *)(data + 44);
+                       partial += *(uint32_t *)(void *)(data + 48);
+                       partial += *(uint32_t *)(void *)(data + 52);
+                       partial += *(uint32_t *)(void *)(data + 56);
+                       partial += *(uint32_t *)(void *)(data + 60);
+                       data += 64;
+                       mlen -= 64;
+                       if (__improbable(partial & (3ULL << 62))) {
+                               if (needs_swap)
+                                       partial = (partial << 8) +
+                                           (partial >> 56);
+                               sum += (partial >> 32);
+                               sum += (partial & 0xffffffff);
+                               partial = 0;
+                       }

                }
                /*
                }
                /*

-                * Unroll the loop to make overhead from
-                * branches &c small.
+                * mlen is not updated below as the remaining tests
+                * are using bit masks, which are not affected.

                 */
                 */

-               while ((mlen -= 32) >= 0) {
-                       sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
-                       sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
-                       sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
-                       sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
-                       w += 16;
+               if (mlen & 32) {
+                       partial += *(uint32_t *)(void *)data;
+                       partial += *(uint32_t *)(void *)(data + 4);
+                       partial += *(uint32_t *)(void *)(data + 8);
+                       partial += *(uint32_t *)(void *)(data + 12);
+                       partial += *(uint32_t *)(void *)(data + 16);
+                       partial += *(uint32_t *)(void *)(data + 20);
+                       partial += *(uint32_t *)(void *)(data + 24);
+                       partial += *(uint32_t *)(void *)(data + 28);
+                       data += 32;

                }
                }

-               mlen += 32;
-               while ((mlen -= 8) >= 0) {
-                       sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
-                       w += 4;
+               if (mlen & 16) {
+                       partial += *(uint32_t *)(void *)data;
+                       partial += *(uint32_t *)(void *)(data + 4);
+                       partial += *(uint32_t *)(void *)(data + 8);
+                       partial += *(uint32_t *)(void *)(data + 12);
+                       data += 16;

                }
                }

-               mlen += 8;
-               if (mlen == 0 && byte_swapped == 0)
-                       continue;
-               REDUCE;
-               while ((mlen -= 2) >= 0) {
-                       sum += *w++;
+               if (mlen & 8) {
+                       partial += *(uint32_t *)(void *)data;
+                       partial += *(uint32_t *)(void *)(data + 4);
+                       data += 8;

                }
                }

-               if (byte_swapped) {
-                       REDUCE;
-                       sum <<= 8;
-                       byte_swapped = 0;
-                       if (mlen == -1) {
-                               s_util.c[1] = *(char *)w;
-                               sum += s_util.s;
-                               mlen = 0;
-                       } else
-                               mlen = -1;
-               } else if (mlen == -1)
-                       s_util.c[0] = *(char *)w;
-       }
-       if (len)
-               printf("cksum: out of data\n");
-       if (mlen == -1) {
-               /* The last mbuf has odd # of bytes. Follow the
-                  standard (the odd byte may be shifted left by 8 bits
-                  or not as determined by endian-ness of the machine) */
-               s_util.c[1] = 0;
-               sum += s_util.s;
+               if (mlen & 4) {
+                       partial += *(uint32_t *)(void *)data;
+                       data += 4;
+               }
+               if (mlen & 2) {
+                       partial += *(uint16_t *)(void *)data;
+                       data += 2;
+               }
+trailing_bytes:
+               if (mlen & 1) {
+#if BYTE_ORDER == LITTLE_ENDIAN
+                       partial += *data;
+#else /* BYTE_ORDER != LITTLE_ENDIAN */
+                       partial += *data << 8;
+#endif /* BYTE_ORDER != LITTLE_ENDIAN */
+                       started_on_odd = !started_on_odd;
+               }
+
+               if (needs_swap)
+                       partial = (partial << 8) + (partial >> 56);
+               sum += (partial >> 32) + (partial & 0xffffffff);
+               /*
+                * Reduce sum to allow potential byte swap
+                * in the next iteration without carry.
+                */
+               sum = (sum >> 32) + (sum & 0xffffffff);

        }
        }

-       REDUCE;
-       KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_END, 0,0,0,0,0);
-       return (~sum & 0xffff);
+       final_acc = (sum >> 48) + ((sum >> 32) & 0xffff) +
+           ((sum >> 16) & 0xffff) + (sum & 0xffff);
+       final_acc = (final_acc >> 16) + (final_acc & 0xffff);
+       final_acc = (final_acc >> 16) + (final_acc & 0xffff);
+       return (final_acc & 0xffff);

 }
 }

-
-#endif
+#endif /* __LP64 */
+#endif /* DEBUG || DEVELOPMENT */