LXR linux/arch/s390/include/asm/checksum.h

   1/*
   2 *    S390 fast network checksum routines
   3 *
   4 *  S390 version
   5 *    Copyright IBM Corp. 1999
   6 *    Author(s): Ulrich Hild        (first version)
   7 *               Martin Schwidefsky (heavily optimized CKSM version)
   8 *               D.J. Barrow        (third attempt) 
   9 */
  10
  11#ifndef _S390_CHECKSUM_H
  12#define _S390_CHECKSUM_H
  13
  14#include <asm/uaccess.h>
  15
  16/*
  17 * computes the checksum of a memory block at buff, length len,
  18 * and adds in "sum" (32-bit)
  19 *
  20 * returns a 32-bit number suitable for feeding into itself
  21 * or csum_tcpudp_magic
  22 *
  23 * this function must be called with even lengths, except
  24 * for the last fragment, which may be odd
  25 *
  26 * it's best to have buff aligned on a 32-bit boundary
  27 */
  28static inline __wsum
  29csum_partial(const void *buff, int len, __wsum sum)
  30{
  31        register unsigned long reg2 asm("2") = (unsigned long) buff;
  32        register unsigned long reg3 asm("3") = (unsigned long) len;
  33
  34        asm volatile(
  35                "0:     cksm    %0,%1\n"        /* do checksum on longs */
  36                "       jo      0b\n"
  37                : "+d" (sum), "+d" (reg2), "+d" (reg3) : : "cc", "memory");
  38        return sum;
  39}
  40
  41/*
  42 * the same as csum_partial_copy, but copies from user space.
  43 *
  44 * here even more important to align src and dst on a 32-bit (or even
  45 * better 64-bit) boundary
  46 *
  47 * Copy from userspace and compute checksum.  If we catch an exception
  48 * then zero the rest of the buffer.
  49 */
  50static inline __wsum
  51csum_partial_copy_from_user(const void __user *src, void *dst,
  52                                          int len, __wsum sum,
  53                                          int *err_ptr)
  54{
  55        int missing;
  56
  57        missing = copy_from_user(dst, src, len);
  58        if (missing) {
  59                memset(dst + len - missing, 0, missing);
  60                *err_ptr = -EFAULT;
  61        }
  62                
  63        return csum_partial(dst, len, sum);
  64}
  65
  66
  67static inline __wsum
  68csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum)
  69{
  70        memcpy(dst,src,len);
  71        return csum_partial(dst, len, sum);
  72}
  73
  74/*
  75 *      Fold a partial checksum without adding pseudo headers
  76 */
  77static inline __sum16 csum_fold(__wsum sum)
  78{
  79        u32 csum = (__force u32) sum;
  80
  81        csum += (csum >> 16) + (csum << 16);
  82        csum >>= 16;
  83        return (__force __sum16) ~csum;
  84}
  85
  86/*
  87 *      This is a version of ip_compute_csum() optimized for IP headers,
  88 *      which always checksum on 4 octet boundaries.
  89 *
  90 */
  91static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  92{
  93        return csum_fold(csum_partial(iph, ihl*4, 0));
  94}
  95
  96/*
  97 * computes the checksum of the TCP/UDP pseudo-header
  98 * returns a 32-bit checksum
  99 */
 100static inline __wsum
 101csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 102                   unsigned short len, unsigned short proto,
 103                   __wsum sum)
 104{
 105        __u32 csum = (__force __u32)sum;
 106
 107        csum += (__force __u32)saddr;
 108        if (csum < (__force __u32)saddr)
 109                csum++;
 110
 111        csum += (__force __u32)daddr;
 112        if (csum < (__force __u32)daddr)
 113                csum++;
 114
 115        csum += len + proto;
 116        if (csum < len + proto)
 117                csum++;
 118
 119        return (__force __wsum)csum;
 120}
 121
 122/*
 123 * computes the checksum of the TCP/UDP pseudo-header
 124 * returns a 16-bit checksum, already complemented
 125 */
 126
 127static inline __sum16
 128csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 129                  unsigned short len, unsigned short proto,
 130                  __wsum sum)
 131{
 132        return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 133}
 134
 135/*
 136 * this routine is used for miscellaneous IP-like checksums, mainly
 137 * in icmp.c
 138 */
 139
 140static inline __sum16 ip_compute_csum(const void *buff, int len)
 141{
 142        return csum_fold(csum_partial(buff, len, 0));
 143}
 144
 145#endif /* _S390_CHECKSUM_H */
 146
 147
 148