Now that linear and IMMR dedicated TLB handling is gone, kernel
boundary address comparison is similar in ITLB miss handler and
in DTLB miss handler.
Create a macro named compare_to_kernel_boundary.
When TASK_SIZE is strictly below 0x80000000 and PAGE_OFFSET is
above 0x80000000, it is enough to compare to 0x8000000, and this
can be done with a single instruction.
Using not. instruction, we get to use 'blt' conditional branch as
when doing a regular comparison:
0x00000000 <= addr <= 0x7fffffff ==>
0xffffffff >= NOT(addr) >= 0x80000000
The above test corresponds to a 'blt'
Otherwise, do a regular comparison using two instructions.
Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
arch/powerpc/kernel/head_8xx.S | 22 ++++++++--------------
1 file changed, 8 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 9f3f7f3d03a7..9a117b9f0998 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -32,10 +32,15 @@
#include "head_32.h"
+.macro compare_to_kernel_boundary scratch, addr
#if CONFIG_TASK_SIZE <= 0x80000000 && CONFIG_PAGE_OFFSET >= 0x80000000
/* By simply checking Address >= 0x80000000, we know if its a kernel address */
-#define SIMPLE_KERNEL_ADDRESS 1
+ not. \scratch, \addr
+#else
+ rlwinm \scratch, \addr, 16, 0xfff8
+ cmpli cr0, \scratch, PAGE_OFFSET@h
#endif
+.endm
/*
* We need an ITLB miss handler for kernel addresses if:
@@ -209,20 +214,11 @@ InstructionTLBMiss:
mtspr SPRN_MD_EPN, r10
#ifdef ITLB_MISS_KERNEL
mfcr r11
-#if defined(SIMPLE_KERNEL_ADDRESS)
- cmpi cr0, r10, 0 /* Address >= 0x80000000 */
-#else
- rlwinm r10, r10, 16, 0xfff8
- cmpli cr0, r10, PAGE_OFFSET@h
-#endif
+ compare_to_kernel_boundary r10, r10
#endif
mfspr r10, SPRN_M_TWB /* Get level 1 table */
#ifdef ITLB_MISS_KERNEL
-#if defined(SIMPLE_KERNEL_ADDRESS)
- bge+ 3f
-#else
blt+ 3f
-#endif
rlwinm r10, r10, 0, 20, 31
oris r10, r10, (swapper_pg_dir - PAGE_OFFSET)@ha
3:
@@ -288,9 +284,7 @@ DataStoreTLBMiss:
* kernel page tables.
*/
mfspr r10, SPRN_MD_EPN
- rlwinm r10, r10, 16, 0xfff8
- cmpli cr0, r10, PAGE_OFFSET@h
-
+ compare_to_kernel_boundary r10, r10
mfspr r10, SPRN_M_TWB /* Get level 1 table */
blt+ 3f
rlwinm r10, r10, 0, 20, 31
--
2.25.0
