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 <linux/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.
  48 */
  49static inline __wsum
  50csum_partial_copy_from_user(const void __user *src, void *dst,
  51                                          int len, __wsum sum,
  52                                          int *err_ptr)
  53{
  54        if (unlikely(copy_from_user(dst, src, len)))
  55                *err_ptr = -EFAULT;
  56        return csum_partial(dst, len, sum);
  57}
  58
  59
  60static inline __wsum
  61csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum)
  62{
  63        memcpy(dst,src,len);
  64        return csum_partial(dst, len, sum);
  65}
  66
  67/*
  68 *      Fold a partial checksum without adding pseudo headers
  69 */
  70static inline __sum16 csum_fold(__wsum sum)
  71{
  72        u32 csum = (__force u32) sum;
  73
  74        csum += (csum >> 16) + (csum << 16);
  75        csum >>= 16;
  76        return (__force __sum16) ~csum;
  77}
  78
  79/*
  80 *      This is a version of ip_compute_csum() optimized for IP headers,
  81 *      which always checksum on 4 octet boundaries.
  82 *
  83 */
  84static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  85{
  86        return csum_fold(csum_partial(iph, ihl*4, 0));
  87}
  88
  89/*
  90 * computes the checksum of the TCP/UDP pseudo-header
  91 * returns a 32-bit checksum
  92 */
  93static inline __wsum
  94csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 proto,
  95                   __wsum sum)
  96{
  97        __u32 csum = (__force __u32)sum;
  98
  99        csum += (__force __u32)saddr;
 100        if (csum < (__force __u32)saddr)
 101                csum++;
 102
 103        csum += (__force __u32)daddr;
 104        if (csum < (__force __u32)daddr)
 105                csum++;
 106
 107        csum += len + proto;
 108        if (csum < len + proto)
 109                csum++;
 110
 111        return (__force __wsum)csum;
 112}
 113
 114/*
 115 * computes the checksum of the TCP/UDP pseudo-header
 116 * returns a 16-bit checksum, already complemented
 117 */
 118
 119static inline __sum16
 120csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, __u8 proto,
 121                  __wsum sum)
 122{
 123        return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 124}
 125
 126/*
 127 * this routine is used for miscellaneous IP-like checksums, mainly
 128 * in icmp.c
 129 */
 130
 131static inline __sum16 ip_compute_csum(const void *buff, int len)
 132{
 133        return csum_fold(csum_partial(buff, len, 0));
 134}
 135
 136#endif /* _S390_CHECKSUM_H */
 137
 138
 139