linux-kernel - Re: [rfc 37/45] x86_64: Support for fast per cpu operations

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 for Android: free password hash cracker in your pocket

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

Message-ID: <47424435.8050704@zytor.com>
Date:	Mon, 19 Nov 2007 18:19:33 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	David Miller <davem@...emloft.net>
CC:	clameter@....com, ak@...e.de, akpm@...ux-foundation.org,
	travis@....com, mathieu.desnoyers@...ymtl.ca,
	linux-kernel@...r.kernel.org
Subject: Re: [rfc 37/45] x86_64: Support for fast per cpu operations

David Miller wrote:
>> There was, at some point, discussion about using the gcc TLS mechanism, 
>> which should permit even better code to be generated.  Unfortunately, it 
>> would require gcc to be able to reference %gs instead of %fs (and vice 
>> versa for i386), which I don't think is available in anything except 
>> maybe the most cutting-edge version of gcc.
> 
> You can't use __thread because GCC will cache __thread computed
> addresses across context switches and cpu changes.
> 
> It's been tried before on powerpc, it doesn't work.

OK, that pretty much answers that question.

	-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/