linux-kernel - Re: [PATCH v3] MIPS: Implement ieee754 NAN2008 emulation mode

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.DEB.2.21.2407101015120.38148@angie.orcam.me.uk>
Date: Wed, 10 Jul 2024 10:21:21 +0100 (BST)
From: "Maciej W. Rozycki" <macro@...am.me.uk>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
cc: Jiaxun Yang <jiaxun.yang@...goat.com>, Jonathan Corbet <corbet@....net>, 
    linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
    "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>, 
    Philippe Mathieu-Daudé <philmd@...aro.org>
Subject: Re: [PATCH v3] MIPS: Implement ieee754 NAN2008 emulation mode

On Wed, 10 Jul 2024, Thomas Bogendoerfer wrote:

> > > I'm considering to apply your patch, how much testing/verification did
> > > this patch see ? Do have some test binaries ?
> > 
> > It has been tested against Debian rootfs. There is no need to test againt special binary,
> > but you need NaN2008 hardware such as Loongson 3A4000.
> 
> that's just one case, what about NaN2008 binaries on a legacy MIPS CPU ?

 It would be good to check with hard-float QEMU configured for writable 
FCSR.NAN2008 (which is one way original code was verified) that things 
have not regressed.  And also what happens if once our emulation has 
triggered for the unsupported FCSR.NAN2008 mode, an attempt is made to 
flip the mode bit via ptrace(2), e.g. under GDB, which I reckon our 
emulation permits for non-legacy CPUs (and which I think should not be 
allowed under the new setting).

  Maciej