Scott Wood [off-list ref] wrote on 30/10/2009 18:37:49:

On Fri, Oct 30, 2009 at 12:16:07PM -0500, Scott Wood wrote:

quoted

On Sat, Oct 17, 2009 at 02:01:38PM +0200, Joakim Tjernlund wrote:

quoted

+     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@h
+     ori   r11, r11, swapper_pg_dir@l
+     rlwimi      r11, r11, 0, 2, 19

That rlwimi is a no-op -- I think you meant to use a different register
here?

quoted

+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:

Yes, I see now that it is wrong.

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.

Would you mind produce a proper path on top of my series? I am blind
here so I can only guess what will work or not.
Then Rex can give it some beating and we can push this to Ben