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: <503450E2.2040504@zytor.com>
Date:	Tue, 21 Aug 2012 20:24:18 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	David Miller <davem@...emloft.net>
CC:	bhutchings@...arflare.com, tglx@...utronix.de, mingo@...hat.com,
	netdev@...r.kernel.org, linux-net-drivers@...arflare.com,
	x86@...nel.org, Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 2/3] x86_64: Define 128-bit memory-mapped I/O operations

On 08/21/2012 07:34 PM, David Miller wrote:
> 
> I really hope we eventually get rid of this rediculous restriction the
> x86 code has.
> 
> It really needs a proper stack of FPU state saves like sparc64 has.
> 
> Half of the code and complexity in arch/x86/crypto/ would just
> disappear, because most of it has to do with handling this obtuse
> FPU usage restriction which shouldn't even be an issue in the first
> place.
> 
> I continually see more and more code that has to check this
> irq_fpu_usable() thing, and have ugly fallback code, and therefore is
> a sign that this really needs to be fixed properly.
> 

[Cc: Linus, since he has had very strong opinions on this in the past.]

I'm all ears... tell me how sparc64 deals with this, maybe we can
implement something similar.  At the same time, do keep in mind that on
x86 this is not just a matter of the FPU state, but the entire "extended
state" which can be very large.

Given the cost of state save/enable, however, nothing is going to change
the need for kernel_fpu_begin/end, nor the fact that those things will
want to bracket large regions.

	-hpa
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ