[PATCH/RFC] powerpc: Pass PID argument to _tlbie (WAS: Apparent kernel bug with GDB on ppc405)

Josh Boyer jwboyer at linux.vnet.ibm.com
Mon Oct 29 23:08:24 EST 2007

On Sat, 27 Oct 2007 17:32:02 +1000
Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:

> Allright, so Matt, let me know if that fixes your problem with gdb, and
> I'll clean the patch up a bit and submit it. I want to double check if
> something similar may be needed for freescale booke.
> Basically, the problem is that things like get_user_pages() can cause
> COW operations which in turn call _tlbie() to be called for translations
> that aren't in the current address space.
> The current 40x and 44x implementation of _tlbie doesn't handle that
> properly as it only invalidates entries in the current PID.
> This is an attempt at fixing it. Untested, I just checked it builds for
> arch/powerpc and arch/ppc. I also haven't looked whether the freescale
> BookE _tlbie needs similar treatement (it will get passed the pid in r4
> with that patch, so if it needs to do something with it, it can). Kumar,
> can you have a look ?

This looks pretty good at first glance.  I'll try to test it out today,
but I'd still like to hear if it solves Matt's problem as I doubt I'll
be able to duplicate it.


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