linux-kernel - Re: getting processor numbers

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:	Tue, 03 Apr 2007 22:16:37 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Eric Dumazet <dada1@...mosbay.com>
CC:	Jeremy Fitzhardinge <jeremy@...p.org>,
	Ulrich Drepper <drepper@...hat.com>,
	Davide Libenzi <davidel@...ilserver.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <ak@...e.de>
Subject: Re: getting processor numbers

Eric Dumazet wrote:
> 
> There is one thing that always worried me.
> 
> Intel & AMD manuals make clear that mixing data and program in the same 
> page is bad for performance.
> 
> In particular, x86_64 vsyscall put jiffies and other 
> vsyscall_gtod_data_t right in the midle of code. That is certainly not 
> wise.
> 
> A probably sane implementation should use two pages, one for code, one 
> for data.
> 

Mutable data should be separated from code.  I think any current CPU 
will do fine as long as they are in separate 128-byte chunks, but they 
need at least that much separation.

Readonly data does not need to be separated from code.

	-hpa
-
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/