LXR linux/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 */
  29static inline __wsum
  30csum_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 */
  50static inline __wsum
  51csum_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
  61static inline __wsum
  62csum_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 */
  71static 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 */
  85static 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 */
  94static inline __wsum
  95csum_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
 120static inline __sum16
 121csum_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
 132static 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
 140