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arm64: csum: Optimise IPv6 header checksum

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Throwing our __uint128_t idioms at csum_ipv6_magic() makes it
about 1.3x-2x faster across a range of microarchitecture/compiler
combinations. Not much in absolute terms, but every little helps.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Robin Murphy 2020-01-20 18:52:29 +00:00 committed by Catalin Marinas
parent 27afb236fe
commit e9c7ddbf8b
2 changed files with 33 additions and 1 deletions
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7
arch/arm64/include/asm/checksum.h
View File

@ -5,7 +5,12 @@
#ifndef __ASM_CHECKSUM_H
#define __ASM_CHECKSUM_H
#include <linux/types.h>
#include <linux/in6.h>
#define _HAVE_ARCH_IPV6_CSUM
__sum16 csum_ipv6_magic(const struct in6_addr *saddr,
const struct in6_addr *daddr,
__u32 len, __u8 proto, __wsum sum);
static inline __sum16 csum_fold(__wsum csum)
{

27
arch/arm64/lib/csum.c
View File

@ -124,3 +124,30 @@ unsigned int do_csum(const unsigned char *buff, int len)
return sum >> 16;
}
__sum16 csum_ipv6_magic(const struct in6_addr *saddr,
const struct in6_addr *daddr,
__u32 len, __u8 proto, __wsum csum)
{
__uint128_t src, dst;
u64 sum = (__force u64)csum;
src = *(const __uint128_t *)saddr->s6_addr;
dst = *(const __uint128_t *)daddr->s6_addr;
sum += (__force u32)htonl(len);
#ifdef __LITTLE_ENDIAN
sum += (u32)proto << 24;
#else
sum += proto;
#endif
src += (src >> 64) | (src << 64);
dst += (dst >> 64) | (dst << 64);
sum = accumulate(sum, src >> 64);
sum = accumulate(sum, dst >> 64);
sum += ((sum >> 32) | (sum << 32));
return csum_fold((__force __wsum)(sum >> 32));
}
EXPORT_SYMBOL(csum_ipv6_magic);