[PATCH] Handle I-TLB Error and Miss separately on 8xx

[Tom Rini]

On Wed, Jan 12, 2005 at 03:17:11PM +0100, Joakim Tjernlund wrote:
> > On Wed, Jan 12, 2005 at 08:53:17AM +0100, Joakim Tjernlund wrote:
> > > > As the code stands currently, there is a bug in the 2.4 and 2.6 handling
> > > > of I-TLB Miss and Error exceptions on 8xx.  The problem is that since we
> > > > treat both of them as the same exception when we hit do_page_fault,
> > > > there is a case where we can incorrectly find that a protection fault
> > > > has occured, when it hasn't.  This is because we check bit 4 of SRR1 in
> > > > both cases, but in the case of an I-TLB Miss, this bit is always set,
> > > > and it only indicates a protection fault on an I-TLB Error.
> > > 
> > > Patch looks good to me, but I want to ask when this error
> > > can be triggered in practice?
> > 
> > It is possible to see this in the real world, as we (<hat=mvista>) found
> > this with a customers app.
> 
> hmm, this app must have been doing something pretty special. Any idea what
> caused it?

Only vaugely.  I'll poke the folks who did the investigation to see if
they recall (the app is quite large) and follow up with details, I hope.

-- 
Tom Rini
http://gate.crashing.org/~trini/