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	Tue, 25 Dec 2001 04:51:34 -0200
Date: Tue, 25 Dec 2001 04:51:34 -0200
From: Ralf Baechle <ralf@oss.sgi.com>
To: Carsten Langgaard <carstenl@mips.com>
Cc: linux-mips@oss.sgi.com
Subject: Re: an old FPU context corruption problem when signal happens
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References: <3C21390A.FA23978D@mvista.com> <3C219A3B.6DA93A75@mips.com> <20011225044125.A16759@dea.linux-mips.net>
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In-Reply-To: <20011225044125.A16759@dea.linux-mips.net>; from ralf@oss.sgi.com on Tue, Dec 25, 2001 at 04:41:25AM -0200
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On Tue, Dec 25, 2001 at 04:41:25AM -0200, Ralf Baechle wrote:

> > Are you sure this hasn't been fix in the latest sources (2.4.16) ?
> > I have send a patch to Ralf, which I believe solves a similar problem as
> > you describe below.
> > 
> > Ralf have you applied the patch ?
> 
> Well, I applied it but it's really broken as something can be.  Just an
> example:
> 
> +       /* 
> +        * FPU emulator may have it's own trampoline active just
> +        * above the user stack, 16-bytes before the next lowest
> +        * 16 byte boundary.  Try to avoid trashing it.
> +        */
> +       sp -= 32;
> 
> So the whole thing needs some overhaul.

Btw, the whole fp trampoline thing will have to die anyway.  Virtually
indexed i-caches on some new types of SMP are making them even more
expensive then they already are.

  Ralf