Hi,
The following is an attempt to fix swapping on 8xx by not touching
_PAGE_ACCESSED bit if the page is not present.
Dan, what do you think?
diff --git a/arch/ppc/kernel/head_8xx.S b/arch/ppc/kernel/head_8xx.S
index de09787..4451828 100644
--- a/arch/ppc/kernel/head_8xx.S
+++ b/arch/ppc/kernel/head_8xx.S
@@ -41,6 +41,22 @@
#else
#define DO_8xx_CPU6(val, reg)
#endif
+
+/* can't overwrite the _PAGE_ACCESSED bit of a non-present page (might
+ contain swap data). */
+#ifdef CONFIG_SWAP
+#define SET_PAGE_ACCESSED(reg, destreg, tmpreg) \
+ andi. tmpreg, reg, _PAGE_PRESENT; \
+ beq 9f; \
+ ori reg, reg, _PAGE_ACCESSED; \
+ stw r10, 0(destreg); \
+9:
+#else
+#define SET_PAGE_ACCESSED(reg, destreg, tmpreg) \
+ ori reg, reg, _PAGE_ACCESSED; \
+ stw reg, 0(destreg);
+#endif
+
.text
.globl _stext
_stext:
@@ -332,8 +348,7 @@ InstructionTLBMiss:
mfspr r11, SPRN_MD_TWC /* ....and get the pte address */
lwz r10, 0(r11) /* Get the pte */
- ori r10, r10, _PAGE_ACCESSED
- stw r10, 0(r11)
+ SET_PAGE_ACCESSED(r10, r11, r3)
/* The Linux PTE won't go exactly into the MMU TLB.
* Software indicator bits 21, 22 and 28 must be clear.
@@ -399,8 +414,7 @@ DataStoreTLBMiss:
mtspr SPRN_MD_TWC, r11
mfspr r11, SPRN_MD_TWC /* get the pte address again */
- ori r10, r10, _PAGE_ACCESSED
- stw r10, 0(r11)
+ SET_PAGE_ACCESSED(r10, r11, r3) /* and update pte in table */
/* The Linux PTE won't go exactly into the MMU TLB.
* Software indicator bits 21, 22 and 28 must be clear.
@@ -507,9 +521,9 @@ DataTLBError:
/* Update 'changed', among others.
*/
- ori r10, r10, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE
+ ori r10, r10, _PAGE_DIRTY|_PAGE_HWWRITE
mfspr r11, SPRN_MD_TWC /* Get pte address again */
- stw r10, 0(r11) /* and update pte in table */
+ SET_PAGE_ACCESSED(r10, r11, r3) /* and update pte in table */
/* The Linux PTE won't go exactly into the MMU TLB.
* Software indicator bits 21, 22 and 28 must be clear.
