Commit e9c7ddbf authored by Robin Murphy's avatar Robin Murphy Committed by Catalin Marinas
Browse files

arm64: csum: Optimise IPv6 header checksum 



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: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 27afb236

arch/arm64/include/asm/checksum.h

+6 −1
Original line number Diff line number Diff line
@@ -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)

{

arch/arm64/lib/csum.c

+27 −0
Original line number Diff line number Diff line
@@ -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);

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