linux-kernel - Re: [RFC Patch v1 32/55] ARC: [optim] Cache "current" in Register r25

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:	Mon, 12 Nov 2012 13:50:12 +0000
From:	Arnd Bergmann <arnd@...db.de>
To:	Vineet.Gupta1@...opsys.com
Cc:	linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
	tglx@...utronix.de
Subject: Re: [RFC Patch v1 32/55] ARC: [optim] Cache "current" in Register r25

On Monday 12 November 2012, Vineet.Gupta1@...opsys.com wrote:
> 
>  endmenu # "Platform Board Configuration"
>  
> +config ARC_CURR_IN_REG
> +       bool "Dedicate Register r25 for current_task pointer"
> +       default y
> +       help
> +         This reserved Register R25 to point to Current Task in
> +         kernel mode. This saves memory access for each such access
> +

This looks like a useful feature if you have 32 GPRs, but why make it
optional? Are there cases where you would disable it?

Another alternative to caching "current" would be to cache the per-cpu
offset, and calculate current from that one.

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/