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/* SPDX-License-Identifier: GPL-2.0 */
/*
* S390 fast network checksum routines
*
* S390 version
* Copyright IBM Corp. 1999
* Author(s): Ulrich Hild (first version)
* Martin Schwidefsky (heavily optimized CKSM version)
* D.J. Barrow (third attempt)
*/
#ifndef _S390_CHECKSUM_H
#define _S390_CHECKSUM_H
#include <linux/uaccess.h>
/*
* computes the checksum of a memory block at buff, length len,
* and adds in "sum" (32-bit)
*
* returns a 32-bit number suitable for feeding into itself
* or csum_tcpudp_magic
*
* this function must be called with even lengths, except
* for the last fragment, which may be odd
*
* it's best to have buff aligned on a 32-bit boundary
*/
static inline __wsum
csum_partial(const void *buff, int len, __wsum sum)
{
register unsigned long reg2 asm("2") = (unsigned long) buff;
register unsigned long reg3 asm("3") = (unsigned long) len;
asm volatile(
"0: cksm %0,%1\n" /* do checksum on longs */
" jo 0b\n"
: "+d" (sum), "+d" (reg2), "+d" (reg3) : : "cc", "memory");
return sum;
}
/*
* Fold a partial checksum without adding pseudo headers
*/
static inline __sum16 csum_fold(__wsum sum)
{
u32 csum = (__force u32) sum;
csum += (csum >> 16) + (csum << 16);
csum >>= 16;
return (__force __sum16) ~csum;
}
/*
* This is a version of ip_compute_csum() optimized for IP headers,
* which always checksum on 4 octet boundaries.
*
*/
static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
return csum_fold(csum_partial(iph, ihl*4, 0));
}
/*
* computes the checksum of the TCP/UDP pseudo-header
* returns a 32-bit checksum
*/
static inline __wsum
csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 proto,
__wsum sum)
{
__u32 csum = (__force __u32)sum;
csum += (__force __u32)saddr;
if (csum < (__force __u32)saddr)
csum++;
csum += (__force __u32)daddr;
if (csum < (__force __u32)daddr)
csum++;
csum += len + proto;
if (csum < len + proto)
csum++;
return (__force __wsum)csum;
}
/*
* computes the checksum of the TCP/UDP pseudo-header
* returns a 16-bit checksum, already complemented
*/
static inline __sum16
csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, __u8 proto,
__wsum sum)
{
return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
}
/*
* this routine is used for miscellaneous IP-like checksums, mainly
* in icmp.c
*/
static inline __sum16 ip_compute_csum(const void *buff, int len)
{
return csum_fold(csum_partial(buff, len, 0));
}
#endif /* _S390_CHECKSUM_H */
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