release/src-rt-6.x.4708/linux/linux-2.6.36/arch/s390/include/asm/checksum.h

   1 #ifndef _S390_CHECKSUM_H
   2 #define _S390_CHECKSUM_H
   3
   4 /*
   5  *  include/asm-s390/checksum.h
   6  *    S390 fast network checksum routines
   7  *    see also arch/S390/lib/checksum.c
   8  *
   9  *  S390 version
  10  *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
  11  *    Author(s): Ulrich Hild        (first version)
  12  *               Martin Schwidefsky (heavily optimized CKSM version)
  13  *               D.J. Barrow        (third attempt)
  14  */
  15
  16 #include <asm/uaccess.h>
  17
  18 /*
  19  * computes the checksum of a memory block at buff, length len,
  20  * and adds in "sum" (32-bit)
  21  *
  22  * returns a 32-bit number suitable for feeding into itself
  23  * or csum_tcpudp_magic
  24  *
  25  * this function must be called with even lengths, except
  26  * for the last fragment, which may be odd
  27  *
  28  * it's best to have buff aligned on a 32-bit boundary
  29  */
  30 static inline __wsum
  31 csum_partial(const void *buff, int len, __wsum sum)
  32 {
  33         register unsigned long reg2 asm("2") = (unsigned long) buff;
  34         register unsigned long reg3 asm("3") = (unsigned long) len;
  35
  36         asm volatile(
  37                 "0:     cksm    %0,%1\n"        /* do checksum on longs */
  38                 "       jo      0b\n"
  39                 : "+d" (sum), "+d" (reg2), "+d" (reg3) : : "cc", "memory");
  40         return sum;
  41 }
  42
  43 /*
  44  * the same as csum_partial_copy, but copies from user space.
  45  *
  46  * here even more important to align src and dst on a 32-bit (or even
  47  * better 64-bit) boundary
  48  *
  49  * Copy from userspace and compute checksum.  If we catch an exception
  50  * then zero the rest of the buffer.
  51  */
  52 static inline __wsum
  53 csum_partial_copy_from_user(const void __user *src, void *dst,
  54                                           int len, __wsum sum,
  55                                           int *err_ptr)
  56 {
  57         int missing;
  58
  59         missing = copy_from_user(dst, src, len);
  60         if (missing) {
  61                 memset(dst + len - missing, 0, missing);
  62                 *err_ptr = -EFAULT;
  63         }
  64
  65         return csum_partial(dst, len, sum);
  66 }
  67
  68
  69 static inline __wsum
  70 csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum)
  71 {
  72         memcpy(dst,src,len);
  73         return csum_partial(dst, len, sum);
  74 }
  75
  76 /*
  77  *      Fold a partial checksum without adding pseudo headers
  78  */
  79 static inline __sum16 csum_fold(__wsum sum)
  80 {
  81         u32 csum = (__force u32) sum;
  82
  83         csum += (csum >> 16) + (csum << 16);
  84         csum >>= 16;
  85         return (__force __sum16) ~csum;
  86 }
  87
  88 /*
  89  *      This is a version of ip_compute_csum() optimized for IP headers,
  90  *      which always checksum on 4 octet boundaries.
  91  *
  92  */
  93 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  94 {
  95         return csum_fold(csum_partial(iph, ihl*4, 0));
  96 }
  97
  98 /*
  99  * computes the checksum of the TCP/UDP pseudo-header
 100  * returns a 32-bit checksum
 101  */
 102 static inline __wsum
 103 csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 104                    unsigned short len, unsigned short proto,
 105                    __wsum sum)
 106 {
 107         __u32 csum = (__force __u32)sum;
 108
 109         csum += (__force __u32)saddr;
 110         if (csum < (__force __u32)saddr)
 111                 csum++;
 112
 113         csum += (__force __u32)daddr;
 114         if (csum < (__force __u32)daddr)
 115                 csum++;
 116
 117         csum += len + proto;
 118         if (csum < len + proto)
 119                 csum++;
 120
 121         return (__force __wsum)csum;
 122 }
 123
 124 /*
 125  * computes the checksum of the TCP/UDP pseudo-header
 126  * returns a 16-bit checksum, already complemented
 127  */
 128
 129 static inline __sum16
 130 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 131                   unsigned short len, unsigned short proto,
 132                   __wsum sum)
 133 {
 134         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 135 }
 136
 137 /*
 138  * this routine is used for miscellaneous IP-like checksums, mainly
 139  * in icmp.c
 140  */
 141
 142 static inline __sum16 ip_compute_csum(const void *buff, int len)
 143 {
 144         return csum_fold(csum_partial(buff, len, 0));
 145 }
 146
 147 #endif /* _S390_CHECKSUM_H */