LXR linux/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 */
  30static inline __wsum
  31csum_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 */
  52static inline __wsum
  53csum_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
  69static inline __wsum
  70csum_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 */
  79static 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 */
  93static 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 */
 102static inline __wsum
 103csum_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
 129static inline __sum16
 130csum_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
 142static 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 */
 148
 149
 150