arch/s390/include/asm/checksum.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  *    S390 fast network checksum routines
   4  *
   5  *  S390 version
   6  *    Copyright IBM Corp. 1999
   7  *    Author(s): Ulrich Hild        (first version)
   8  *               Martin Schwidefsky (heavily optimized CKSM version)
   9  *               D.J. Barrow        (third attempt)
  10  */
  11
  12 #ifndef _S390_CHECKSUM_H
  13 #define _S390_CHECKSUM_H
  14
  15 #include <linux/uaccess.h>
  16
  17 /*
  18  * computes the checksum of a memory block at buff, length len,
  19  * and adds in "sum" (32-bit)
  20  *
  21  * returns a 32-bit number suitable for feeding into itself
  22  * or csum_tcpudp_magic
  23  *
  24  * this function must be called with even lengths, except
  25  * for the last fragment, which may be odd
  26  *
  27  * it's best to have buff aligned on a 32-bit boundary
  28  */
  29 static inline __wsum
  30 csum_partial(const void *buff, int len, __wsum sum)
  31 {
  32         register unsigned long reg2 asm("2") = (unsigned long) buff;
  33         register unsigned long reg3 asm("3") = (unsigned long) len;
  34
  35         asm volatile(
  36                 "0:     cksm    %0,%1\n"        /* do checksum on longs */
  37                 "       jo      0b\n"
  38                 : "+d" (sum), "+d" (reg2), "+d" (reg3) : : "cc", "memory");
  39         return sum;
  40 }
  41
  42 static inline __wsum
  43 csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum)
  44 {
  45         memcpy(dst,src,len);
  46         return csum_partial(dst, len, sum);
  47 }
  48
  49 /*
  50  *      Fold a partial checksum without adding pseudo headers
  51  */
  52 static inline __sum16 csum_fold(__wsum sum)
  53 {
  54         u32 csum = (__force u32) sum;
  55
  56         csum += (csum >> 16) + (csum << 16);
  57         csum >>= 16;
  58         return (__force __sum16) ~csum;
  59 }
  60
  61 /*
  62  *      This is a version of ip_compute_csum() optimized for IP headers,
  63  *      which always checksum on 4 octet boundaries.
  64  *
  65  */
  66 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  67 {
  68         return csum_fold(csum_partial(iph, ihl*4, 0));
  69 }
  70
  71 /*
  72  * computes the checksum of the TCP/UDP pseudo-header
  73  * returns a 32-bit checksum
  74  */
  75 static inline __wsum
  76 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 proto,
  77                    __wsum sum)
  78 {
  79         __u32 csum = (__force __u32)sum;
  80
  81         csum += (__force __u32)saddr;
  82         if (csum < (__force __u32)saddr)
  83                 csum++;
  84
  85         csum += (__force __u32)daddr;
  86         if (csum < (__force __u32)daddr)
  87                 csum++;
  88
  89         csum += len + proto;
  90         if (csum < len + proto)
  91                 csum++;
  92
  93         return (__force __wsum)csum;
  94 }
  95
  96 /*
  97  * computes the checksum of the TCP/UDP pseudo-header
  98  * returns a 16-bit checksum, already complemented
  99  */
 100
 101 static inline __sum16
 102 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, __u8 proto,
 103                   __wsum sum)
 104 {
 105         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 106 }
 107
 108 /*
 109  * this routine is used for miscellaneous IP-like checksums, mainly
 110  * in icmp.c
 111  */
 112
 113 static inline __sum16 ip_compute_csum(const void *buff, int len)
 114 {
 115         return csum_fold(csum_partial(buff, len, 0));
 116 }
 117
 118 #endif /* _S390_CHECKSUM_H */
 119
 120