From 0e455d8e80aa22d7ed42c9f5e4e3a75c558aa543 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Tue, 31 May 2016 18:04:40 +0100 Subject: [PATCH] arm64: Implement optimised IP checksum helpers AArch64 is capable of 128-bit memory accesses without alignment restrictions, which makes it both possible and highly practical to slurp up a typical 20-byte IP header in just 2 loads. Implement our own version of ip_fast_checksum() to take advantage of that, resulting in considerably fewer instructions and memory accesses than the generic version. We can also get more optimal code generation for csum_fold() by defining it a slightly different way round from the generic version, so throw that into the mix too. Suggested-by: Luke Starrett Acked-by: Luke Starrett Signed-off-by: Robin Murphy Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/Kbuild | 1 - arch/arm64/include/asm/checksum.h | 51 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 51 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/include/asm/checksum.h diff --git a/arch/arm64/include/asm/Kbuild b/arch/arm64/include/asm/Kbuild index cff532a6744e..f43d2c44c765 100644 --- a/arch/arm64/include/asm/Kbuild +++ b/arch/arm64/include/asm/Kbuild @@ -1,6 +1,5 @@ generic-y += bug.h generic-y += bugs.h -generic-y += checksum.h generic-y += clkdev.h generic-y += cputime.h generic-y += current.h diff --git a/arch/arm64/include/asm/checksum.h b/arch/arm64/include/asm/checksum.h new file mode 100644 index 000000000000..09f65339d66d --- /dev/null +++ b/arch/arm64/include/asm/checksum.h @@ -0,0 +1,51 @@ +/* + * Copyright (C) 2016 ARM Ltd. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + */ +#ifndef __ASM_CHECKSUM_H +#define __ASM_CHECKSUM_H + +#include + +static inline __sum16 csum_fold(__wsum csum) +{ + u32 sum = (__force u32)csum; + sum += (sum >> 16) | (sum << 16); + return ~(__force __sum16)(sum >> 16); +} +#define csum_fold csum_fold + +static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) +{ + __uint128_t tmp; + u64 sum; + + tmp = *(const __uint128_t *)iph; + iph += 16; + ihl -= 4; + tmp += ((tmp >> 64) | (tmp << 64)); + sum = tmp >> 64; + do { + sum += *(const u32 *)iph; + iph += 4; + } while (--ihl); + + sum += ((sum >> 32) | (sum << 32)); + return csum_fold(sum >> 32); +} +#define ip_fast_csum ip_fast_csum + +#include + +#endif /* __ASM_CHECKSUM_H */ -- 2.11.0