Re: [PATCH] TX49 MFC0 bug workaround

[Sergei Shtylylov <sshtylyov@ru.mvista.com>]

Hello.

Atsushi Nemoto wrote:

> > > > > > On Thu, 02 Feb 2006 21:46:25 +0300, Sergei Shtylylov <sshtylyov@ru.mvista.com> 
> > > > > > said:
> > > If mfc0 $12 follows store and the mfc0 is last instruction of a
> > > page and fetching the next instruction causes TLB miss, the result
> > > of the mfc0 might wrongly contain EXL bit.
>
> sshtylyov>     Hmm, a TLB miss in fetching from KSEG0?!
>
> We can call these inline functions from modules running on KSEG2.
   Hm, I'm still learning Linux/MIPS, and have overlooked #ifdef MODULE. :-<

   If I don't mistake, the offending code is in local_irq_disable, 
local_irq_save, and local_irq_restore macros. The effect would be a crash on 
any exception taken once interrupts get disabled in a module (*and* that code 
happens to fall on a page boundary)... nasty. :-(
> ---
> Atsushi Nemoto
WBR, Sergei