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]
Message-ID: <alpine.LFD.1.10.0901151353530.5737@ftp.linux-mips.org>
Date:	Thu, 15 Jan 2009 14:15:56 +0000 (GMT)
From:	"Maciej W. Rozycki" <macro@...ux-mips.org>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
cc:	Jan-Benedict Glaw <jbglaw@...-owl.de>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Jiri Kosina <jkosina@...e.cz>, Adam Osuchowski <adwol@...k.pl>,
	linux-kernel@...r.kernel.org, Nick Piggin <npiggin@...e.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: Is 386 processor still supported?

On Thu, 15 Jan 2009, Alan Cox wrote:

> >  UP emulation of CMPXCHG and XADD for userland should be rather trivial, 
> > so why not include it like with LL/SC for MIPS?
> 
> Why not just ship an additional libc with the right options ?

 Does not work for MIPS as glibc has no equivalent code for pre-LL/SC CPUs 
and LL/SC is always used.  For the i386 the situation seems worse yet as 
for pre-i486 CPUs a generic C implementation of compare-and-exchange is 
used guaranteeing silent thread unsafety. :(

 IMO, a kernel emulation of CMPXCHG and XADD (both are used by 
sysdeps/i386/i486/bits/atomic.h in glibc) with an optional LOCK prefix, 
guaranteeing UP atomicity would be a cheap way to provide long-term i386 
userland support with little burden for both Linux and respective user 
software maintainers.  Certainly it adds some bloat to the kernel, but I 
think it is not an option that should be outright dismissed without 
consideration.

  Maciej
--
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/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ