powerpc/8xx: Restore _PAGE_WRITETHRU
8xx has not had WRITETHRU due to lack of bits in the pte.
After the recent rewrite of the 8xx TLB code, there are
two bits left. Use one of them to WRITETHRU.
Perhaps use the last SW bit to PAGE_SPECIAL or PAGE_FILE?
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 1a28ee8..c4ae85b 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -422,6 +422,10 @@
* above.
*/
rlwimi r11, r10, 0, 27, 27
+ /* Insert the WriteThru flag into the TWC from the Linux PTE.
+ * It is bit 25 in the Linux PTE and bit 30 in the TWC
+ */
+ rlwimi r11, r10, 32-5, 30, 30
DO_8xx_CPU6(0x3b80, r3)
mtspr SPRN_MD_TWC, r11
@@ -559,6 +563,10 @@
* It is bit 27 of both the Linux PTE and the TWC
*/
rlwimi r11, r10, 0, 27, 27
+ /* Insert the WriteThru flag into the TWC from the Linux PTE.
+ * It is bit 25 in the Linux PTE and bit 30 in the TWC
+ */
+ rlwimi r11, r10, 32-5, 30, 30
DO_8xx_CPU6(0x3b80, r3)
mtspr SPRN_MD_TWC, r11
mfspr r11, SPRN_MD_TWC /* get the pte address again */