[PATCH] 8xx: fix user space TLB walk in dcbX fixup

[Joakim Tjernlund]

Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote on 12/01/2010 03:40:45:
>
> On Fri, 2010-01-08 at 17:46 +0100, Joakim Tjernlund wrote:
> > The newly added fixup for buggy dcbX insn's has
> > a bug that always trigger a kernel TLB walk so a user space
> > dcbX insn will cause a Kernel Machine Check if it hits DTLB error.
> >
> > Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund at transmode.se>
> > ---
> >
> > I found this problem in 2.4 and forward ported it to 2.6. I
> > cannot test it so I cannot be 100% sure I got it right.
> >
> >  arch/powerpc/kernel/head_8xx.S |    4 ++--
> >  1 files changed, 2 insertions(+), 2 deletions(-)
>
> Do you have something to make sure that TASK_SIZE is never bigger than
> 2G ? Else userspace could be all the way to 0xbfffffff ...

No, but this is 8xx :) The TLB handlers has the same "limitation" and has always
been so.

      Jocke