Benjamin Herrenschmidt <b...@kernel.crashing.org> wrote on 03/10/2009 10:31:18:
>
> On Sat, 2009-10-03 at 10:05 +0200, Joakim Tjernlund wrote:
> > Cannot shake the feeling that it this snip of code that causes it
> > lwz r11, 0(r10) /* Get the level 1 entry */
> > rlwinm. r10, r11,0,0,19 /* Extract page descriptor page
> > address */
> > beq 2f /* If zero, don't try to find a pte */
> > Perhaps we can do something better? I still feel that we need to
> > force a TLB Error as the TLBMiss does not set DSISR so we have no way
> > of
> > knowing if it is an load or store.
>
> Can't we manufacture a DSISR and branch to the right function ?
Not if we want know if it is a load or store. There is no info to manufacture
a DSISR from. The best we can do here is try getting the RPN physical page
number correct. Perhaps something like this will do:
/* Copy 20 msb from MD_EPN to r20 to get the correct page
* number. Do not rely on DAR since the dcxx instructions fails
* to update DAR when they cause a DTLB Miss
*/
mfspr r21, MD_EPN
li r20, 0x0
rlwimi r20, r21, 0, 0, 19
Then go back and set the RPN accordingly.
The 8xx is different as as it will force a TLB error every time
it needs to deal with a page fault.
I suspect adding
if (!ret)
_tlbil_va(address);
in do_page_fault() will do the trick too.
So yes, there is a missing _tlbil_va() missing for 8xx somewhere
but there is something more too.
Maybe your new filter functions and my
powerpc, 8xx: DTLB Error must check for more errors.
will do the trick?
Jocke
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