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

Tom Rini trini at kernel.crashing.org
Thu Jan 13 01:06:30 EST 2005

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.

Tom Rini

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