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s390/checksum: provide csum_ipv6_magic()

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This implementation needs only ~30% of the time to calculate the
checksum compared to the generic variant. In addition the compiler
also generates only ~30% of the instructions compared to the generic
variant (on z14, compiled with march=z196).

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2020-08-11 11:16:51 +02:00 committed by Vasily Gorbik
parent d012a7190f
commit b064904c50
1 changed files with 22 additions and 2 deletions
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24
arch/s390/include/asm/checksum.h
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@ -13,6 +13,7 @@
#define _S390_CHECKSUM_H
#include <linux/uaccess.h>
#include <linux/in6.h>
/*
* computes the checksum of a memory block at buff, length len,
@ -115,6 +116,25 @@ static inline __sum16 ip_compute_csum(const void *buff, int len)
return csum_fold(csum_partial(buff, len, 0));
}
#define _HAVE_ARCH_IPV6_CSUM
static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
const struct in6_addr *daddr,
__u32 len, __u8 proto, __wsum csum)
{
__u64 sum = (__force __u64)csum;
sum += (__force __u32)saddr->s6_addr32[0];
sum += (__force __u32)saddr->s6_addr32[1];
sum += (__force __u32)saddr->s6_addr32[2];
sum += (__force __u32)saddr->s6_addr32[3];
sum += (__force __u32)daddr->s6_addr32[0];
sum += (__force __u32)daddr->s6_addr32[1];
sum += (__force __u32)daddr->s6_addr32[2];
sum += (__force __u32)daddr->s6_addr32[3];
sum += len;
sum += proto;
sum += (sum >> 32) | (sum << 32);
return csum_fold((__force __wsum)(sum >> 32));
}
#endif /* _S390_CHECKSUM_H */