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.  If we catch an exception
  48  * then zero the rest of the buffer.
  49  */
  50 static inline __wsum
  51 csum_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
  67 static inline __wsum
  68 csum_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  */
  77 static 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  */
  91 static 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  */
 100 static inline __wsum
 101 csum_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
 127 static inline __sum16
 128 csum_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
 140 static 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