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Re: an old FPU context corruption problem when signal happens

To: Ralf Baechle <ralf@oss.sgi.com>
Subject: Re: an old FPU context corruption problem when signal happens
From: Carsten Langgaard <carstenl@mips.com>
Date: Thu, 27 Dec 2001 11:53:00 +0100
Cc: Jun Sun <jsun@mvista.com>, linux-mips@oss.sgi.com
References: <3C21390A.FA23978D@mvista.com> <3C219A3B.6DA93A75@mips.com> <20011225044125.A16759@dea.linux-mips.net>
Sender: owner-linux-mips@oss.sgi.com
Ralf Baechle wrote:

> On Thu, Dec 20, 2001 at 08:58:51AM +0100, Carsten Langgaard 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.
>

You are welcome to find a better way of handling a non-fpu instruction in the
delay slot of the fpu-branch instruction.
But until someone find a better solution (that works, in all situation), I
think we need this patch.


>   Ralf

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