[PATCH 6/8] 8xx: Add missing Guarded setting in DTLB Error.

Joakim Tjernlund joakim.tjernlund at transmode.se
Mon Oct 12 17:59:09 EST 2009

Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote on 12/10/2009 07:46:14:
> On Mon, 2009-10-12 at 07:36 +0200, Joakim Tjernlund wrote:
> > Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote on 12/10/2009 00:44:56:
> > > On Mon, 2009-10-12 at 00:19 +0200, Joakim Tjernlund wrote:
> > > >
> > > > I hear you, I can remove DTLB error with an add on patch later if that is OK?
> > > > I cannot remove the DARFix though, when I move that to do_page_fault(), I get
> > > > duplicate TLB hits on the same insn. It is like when transfer_to_handler()
> > > > executes rfi, the cpu restarts the the faulting insn instead of jumping
> > > > to the page fault handler, not always but often.
> > >
> > > I'm not sure what you mean here ...
> >
> > Just that I need to keep the DAR fix for dcbX insn in the DTLB handler. If I try
> > to move it to do_page_fault() I get a lot more DTLB errors for dcbX insn.
> I'm not sure why (ie, I didn't get your explanation about rfi and
> restarting the faulting insn etc...) but ok, I don't mind having
> the DAR fixup remain in the asm. It's the whole logic that looks
> at the PTE and does things with it that I feel has no room in there :-)

OK, I will send a removal patch too.

> BTW. Maybe the do_page_fault() thing comes from the fact that we
> also go there via ITLB Error which doesn't set the DAR and
> that's normal ?

I had that idea to, but no. These have different traps numbers and
address is set to SRR0 for ITLB and to DAR for DTLB. I test for DTLB
trap number before doing anything.

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