include/asm-s390/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  */
  30 static inline __wsum
  31 csum_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  */
  52 static inline __wsum
  53 csum_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
  69 static inline __wsum
  70 csum_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  */
  79 static inline __sum16 csum_fold(__wsum sum)
  80 {
  81 #ifndef __s390x__
  82         register_pair rp;
  83
  84         asm volatile(
  85                 "       slr     %N1,%N1\n"      /* %0 = H L */
  86                 "       lr      %1,%0\n"        /* %0 = H L, %1 = H L 0 0 */
  87                 "       srdl    %1,16\n"        /* %0 = H L, %1 = 0 H L 0 */
  88                 "       alr     %1,%N1\n"       /* %0 = H L, %1 = L H L 0 */
  89                 "       alr     %0,%1\n"        /* %0 = H+L+C L+H */
  90                 "       srl     %0,16\n"        /* %0 = H+L+C */
  91                 : "+&d" (sum), "=d" (rp) : : "cc");
  92 #else /* __s390x__ */
  93         asm volatile(
  94                 "       sr      3,3\n"          /* %0 = H*65536 + L */
  95                 "       lr      2,%0\n"         /* %0 = H L, 2/3 = H L / 0 0 */
  96                 "       srdl    2,16\n"         /* %0 = H L, 2/3 = 0 H / L 0 */
  97                 "       alr     2,3\n"          /* %0 = H L, 2/3 = L H / L 0 */
  98                 "       alr     %0,2\n"         /* %0 = H+L+C L+H */
  99                 "       srl     %0,16\n"        /* %0 = H+L+C */
 100                 : "+&d" (sum) : : "cc", "2", "3");
 101 #endif /* __s390x__ */
 102         return (__force __sum16) ~sum;
 103 }
 104
 105 /*
 106  *      This is a version of ip_compute_csum() optimized for IP headers,
 107  *      which always checksum on 4 octet boundaries.
 108  *
 109  */
 110 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
 111 {
 112         return csum_fold(csum_partial(iph, ihl*4, 0));
 113 }
 114
 115 /*
 116  * computes the checksum of the TCP/UDP pseudo-header
 117  * returns a 32-bit checksum
 118  */
 119 static inline __wsum
 120 csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 121                    unsigned short len, unsigned short proto,
 122                    __wsum sum)
 123 {
 124         __u32 csum = (__force __u32)sum;
 125
 126         csum += (__force __u32)saddr;
 127         if (csum < (__force __u32)saddr)
 128                 csum++;
 129
 130         csum += (__force __u32)daddr;
 131         if (csum < (__force __u32)daddr)
 132                 csum++;
 133
 134         csum += len + proto;
 135         if (csum < len + proto)
 136                 csum++;
 137
 138         return (__force __wsum)csum;
 139 }
 140
 141 /*
 142  * computes the checksum of the TCP/UDP pseudo-header
 143  * returns a 16-bit checksum, already complemented
 144  */
 145
 146 static inline __sum16
 147 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 148                   unsigned short len, unsigned short proto,
 149                   __wsum sum)
 150 {
 151         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 152 }
 153
 154 /*
 155  * this routine is used for miscellaneous IP-like checksums, mainly
 156  * in icmp.c
 157  */
 158
 159 static inline __sum16 ip_compute_csum(const void *buff, int len)
 160 {
 161         return csum_fold(csum_partial(buff, len, 0));
 162 }
 163
 164 #endif /* _S390_CHECKSUM_H */
 165
 166