[PATCH 0/8] Fix 8xx MMU/TLB

[Joakim Tjernlund]

Scott Wood <scottwood at freescale.com> wrote on 30/10/2009 18:37:49:
>
> On Fri, Oct 30, 2009 at 12:16:07PM -0500, Scott Wood wrote:
> > On Sat, Oct 17, 2009 at 02:01:38PM +0200, Joakim Tjernlund wrote:
> > > +     mfspr r10, SPRN_SRR0
> > >       DO_8xx_CPU6(0x3780, r3)
> > >       mtspr SPRN_MD_EPN, r10
> > >       mfspr r11, SPRN_M_TWB   /* Get level 1 table entry address */
> > > -     lwz   r11, 0(r11)   /* Get the level 1 entry */
> > > +     cmplwi      cr0, r11, 0x0800
> > > +     blt-  3f      /* Branch if user space */
> > > +     lis   r11, swapper_pg_dir at h
> > > +     ori   r11, r11, swapper_pg_dir at l
> > > +     rlwimi      r11, r11, 0, 2, 19
> >
> > That rlwimi is a no-op -- I think you meant to use a different register
> > here?
> >
> > > +3:   lwz   r11, 0(r11)   /* Get the level 1 entry */
> > >       DO_8xx_CPU6(0x3b80, r3)
> > >       mtspr SPRN_MD_TWC, r11   /* Load pte table base address */
> > >       mfspr r11, SPRN_MD_TWC   /* ....and get the pte address */
> > >       lwz   r11, 0(r11)   /* Get the pte */
> > >       /* concat physical page address(r11) and page offset(r10) */
> > >       rlwimi      r11, r10, 0, 20, 31
> >
> > But r10 here contains SRR0 from above, and this is a data TLB error.
>
> Never mind that last one, forgot that you'd be wanting to load the
> instruction. :-P
>
> But the rlwimi is what's causing the machine checks.  I replaced it with:
> rlwinm   r11, r11, 0, 0x3ffff000
> rlwimi   r11, r10, 22, 0xffc
>
> and things seem to work.  You could probably replace the rlwinm by
> subtracting PAGE_OFFSET from swapper_pg_dir instead.

Just guessing here, do you mean:
	lis	r11, (swapper_pg_dir-PAGE_OFFSET)@h
	ori	r11, r11, (swapper_pg_dir-PAGE_OFFSET)@l
	rlwimi	r11, r10, 22, 0xffc
or
	lis	r11, swapper_pg_dir at h
	ori	r11, r11, swapper_pg_dir at l
	subis	r11, r11 PAGE_OFFSET
	rlwimi	r11, r10, 22, 0xffc

 Jocke