netdev - Re: [PATCH v5 net-next] net: Implement fast csum_partial for x86

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 02 Mar 2016 14:35:39 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Tom Herbert <tom@...bertland.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	torvalds@...ux-foundation.org, tglx@...utronix.de,
	mingo@...hat.com, hpa@...or.com, x86@...nel.org, kernel-team@...com
Subject: Re: [PATCH v5 net-next] net: Implement fast csum_partial for x86_64

On mer., 2016-03-02 at 14:18 -0800, Tom Herbert wrote:
\
> +	asm("lea 0f(, %[slen], 4), %%r11\n\t"
> +	    "clc\n\t"
> +	    "jmpq *%%r11\n\t"
> +	    "adcq 7*8(%[src]),%[res]\n\t"
> +	    "adcq 6*8(%[src]),%[res]\n\t"
> +	    "adcq 5*8(%[src]),%[res]\n\t"
> +	    "adcq 4*8(%[src]),%[res]\n\t"
> +	    "adcq 3*8(%[src]),%[res]\n\t"
> +	    "adcq 2*8(%[src]),%[res]\n\t"
> +	    "adcq 1*8(%[src]),%[res]\n\t"
> +	    "adcq 0*8(%[src]),%[res]\n\t"
> +	    "nop\n\t"
> +	    "0: adcq $0,%[res]"
> +		    : [res] "=r" (result)
> +		    : [src] "r" (buff),
> +		      [slen] "r" (-(unsigned long)(len >> 3)), "[res]" (result)
> +		    : "r11");
>  


hpa mentioned we could use adcq.d8 0*8(%[src]),%[res]

to avoid the mandatory 'nop'