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  */
  28 static inline __wsum
  29 csum_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  */
  49 static inline __wsum
  50 csum_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
  60 static inline __wsum
  61 csum_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  */
  70 static 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  */
  84 static 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  */
  93 static inline __wsum
  94 csum_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
 119 static inline __sum16
 120 csum_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
 131 static 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