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Re: 64 bit operations w/32 bit kernel

To: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Subject: Re: 64 bit operations w/32 bit kernel
From: Ralf Baechle <ralf@linux-mips.org>
Date: Wed, 1 Oct 2003 18:24:20 +0200
Cc: Michael Uhler <uhler@mips.com>, "Finney, Steve" <Steve.Finney@spirentcom.com>, linux-mips@linux-mips.org
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On Wed, Oct 01, 2003 at 06:26:02AM +0200, Maciej W. Rozycki wrote:

> > was never intended to run real 32-bit programs with 64-bit ops enabled,
> > and I would strongly urge you not to do this now.
> 
>  After a bit of thinking, I consider this not to be a real problem.  Apart
> from the kernel interface, which sanitizes values passed, the rest is pure
> userland, where allowing undefined operation with 64-bit opcodes cannot
> really hurt.  Of course running a buggy or malicious program may lead to
> bad results or loss of data, but it'll be limited to the user responsible
> for running such software and the root user by definition has to know what
> he is doing and specifically he is responsible for not running untrusted
> software on critical systems.
> 
>  That said, I don't really have a strong preference either way -- it just
> doesn't seem to be worth the hassle for me to explicitly defend against
> such a marginal case.  Although it may be good to try validating this
> assumption with `crashme'. 

It's a while since this last has been done and all bugs showing up were
fixed ...

  Ralf

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