Non-booting G5

[David Gibson]

On Tue, Aug 30, 2005 at 11:11:00AM -0700, Linus Torvalds wrote:
> 
> This commit causes my G5 to not boot at all. It just hangs very early on 
> in the boot sequence.
> 
> The good news is that I used this bug to verify (and fix an off-by-one
> error) the git bisection thing. The previous commit works fine ("ppc64: 
> Check of_chosen..")
> 
> I won't have time to test anything else, since my flight to Italy leaves 
> in a couple of hours, but hopefully this is enough for people to start on.
> 
> I don't have anything strange in my config, but I'm appending that as a
> gzipped attachment in case people care.

Fix bug in ppc64 dynamic hugepage support

I'm an idiot.  In adjusting the logic for SLB miss for the dynamic
hugepage stuff, I messed up the !CONFIG_HUGETLB_PAGE case, failing to
set the SLB flags properly.

This patch fixes it.  It also streamlines the logic for the
CONFIG_HUGETLB_PAGE case (removing a couple of branches) while we're
at it.

Booted, and roughly tested on POWER5 (with and without
CONFIG_HUGETLB_PAGE), iSeries/RS64 (no hugepage available), and G5
(with and without CONFIG_HUGETLB_PAGE).

Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

Index: working-2.6/arch/ppc64/mm/slb_low.S
===================================================================
--- working-2.6.orig/arch/ppc64/mm/slb_low.S	2005-08-31 13:46:45.000000000 +1000
+++ working-2.6/arch/ppc64/mm/slb_low.S	2005-08-31 13:46:45.000000000 +1000
@@ -97,25 +97,21 @@
 	lhz	r9,PACAHIGHHTLBAREAS(r13)
 	srdi	r11,r3,(HTLB_AREA_SHIFT-SID_SHIFT)
 	srd	r9,r9,r11
-	andi.	r9,r9,1
-	bne	5f
+	lhz	r11,PACALOWHTLBAREAS(r13)
+	srd	r11,r11,r3
+	or	r9,r9,r11
+END_FTR_SECTION_IFSET(CPU_FTR_16M_PAGE)
+#endif /* CONFIG_HUGETLB_PAGE */
 
 	li	r11,SLB_VSID_USER
 
-	cmpldi	r3,16
-	bge	6f
-
-	lhz	r9,PACALOWHTLBAREAS(r13)
-	srd	r9,r9,r3
-	andi.	r9,r9,1
-
-	beq	6f
-
-5:	li	r11,SLB_VSID_USER|SLB_VSID_L
+#ifdef CONFIG_HUGETLB_PAGE
+BEGIN_FTR_SECTION
+	rldimi	r11,r9,8,55		/* shift masked bit into SLB_VSID_L */
 END_FTR_SECTION_IFSET(CPU_FTR_16M_PAGE)
 #endif /* CONFIG_HUGETLB_PAGE */
 
-6:	ld	r9,PACACONTEXTID(r13)
+	ld	r9,PACACONTEXTID(r13)
 	rldimi	r3,r9,USER_ESID_BITS,0
 
 9:	/* r3 = protovsid, r11 = flags, r10 = esid_data, cr7 = <>KERNELBASE */

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/people/dgibson