linux-mips
[Top] [All Lists]

Re: an old FPU context corruption problem when signal happens

To: Carsten Langgaard <carstenl@mips.com>
Subject: Re: an old FPU context corruption problem when signal happens
From: Ralf Baechle <ralf@oss.sgi.com>
Date: Tue, 25 Dec 2001 04:51:34 -0200
Cc: linux-mips@oss.sgi.com
In-reply-to: <20011225044125.A16759@dea.linux-mips.net>; from ralf@oss.sgi.com on Tue, Dec 25, 2001 at 04:41:25AM -0200
References: <3C21390A.FA23978D@mvista.com> <3C219A3B.6DA93A75@mips.com> <20011225044125.A16759@dea.linux-mips.net>
Sender: owner-linux-mips@oss.sgi.com
User-agent: Mutt/1.2.5i
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

<Prev in Thread] Current Thread [Next in Thread>