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

[Josh Boyer]

On Mon, 29 Oct 2007 07:08:24 -0500
Josh Boyer <jwboyer at linux.vnet.ibm.com> wrote:

> 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.

Did a boot test on my ebony board with this patch included.  It seems
to be happy about things so far.  If Matt gets around to trying this
out and it works, we should probably look at getting this into 2.6.24.

Oh, and I'd need a signed-off-by for it Ben :)

josh