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 /*
  43  * the same as csum_partial_copy, but copies from user space.
  44  *
  45  * here even more important to align src and dst on a 32-bit (or even
  46  * better 64-bit) boundary
  47  *
  48  * Copy from userspace and compute checksum.
  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         if (unlikely(copy_from_user(dst, src, len)))
  56                 *err_ptr = -EFAULT;
  57         return csum_partial(dst, len, sum);
  58 }
  59
  60
  61 static inline __wsum
  62 csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum)
  63 {
  64         memcpy(dst,src,len);
  65         return csum_partial(dst, len, sum);
  66 }
  67
  68 /*
  69  *      Fold a partial checksum without adding pseudo headers
  70  */
  71 static inline __sum16 csum_fold(__wsum sum)
  72 {
  73         u32 csum = (__force u32) sum;
  74
  75         csum += (csum >> 16) + (csum << 16);
  76         csum >>= 16;
  77         return (__force __sum16) ~csum;
  78 }
  79
  80 /*
  81  *      This is a version of ip_compute_csum() optimized for IP headers,
  82  *      which always checksum on 4 octet boundaries.
  83  *
  84  */
  85 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  86 {
  87         return csum_fold(csum_partial(iph, ihl*4, 0));
  88 }
  89
  90 /*
  91  * computes the checksum of the TCP/UDP pseudo-header
  92  * returns a 32-bit checksum
  93  */
  94 static inline __wsum
  95 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 proto,
  96                    __wsum sum)
  97 {
  98         __u32 csum = (__force __u32)sum;
  99
 100         csum += (__force __u32)saddr;
 101         if (csum < (__force __u32)saddr)
 102                 csum++;
 103
 104         csum += (__force __u32)daddr;
 105         if (csum < (__force __u32)daddr)
 106                 csum++;
 107
 108         csum += len + proto;
 109         if (csum < len + proto)
 110                 csum++;
 111
 112         return (__force __wsum)csum;
 113 }
 114
 115 /*
 116  * computes the checksum of the TCP/UDP pseudo-header
 117  * returns a 16-bit checksum, already complemented
 118  */
 119
 120 static inline __sum16
 121 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, __u8 proto,
 122                   __wsum sum)
 123 {
 124         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 125 }
 126
 127 /*
 128  * this routine is used for miscellaneous IP-like checksums, mainly
 129  * in icmp.c
 130  */
 131
 132 static inline __sum16 ip_compute_csum(const void *buff, int len)
 133 {
 134         return csum_fold(csum_partial(buff, len, 0));
 135 }
 136
 137 #endif /* _S390_CHECKSUM_H */
 138
 139