Re: [PATCH 05/11] powerpc/8xx: Optimise access to swapper_pg_dir
From: leroy christophe
Date: Tue Jan 06 2015 - 08:27:45 EST
Le 06/01/2015 13:08, David Laight a écrit :
On Tue, 2014-12-16 at 16:03 +0100, Christophe Leroy wrote:
All accessed to PGD entries are done via 0(r11).
By using lower part of swapper_pg_dir as load index to r11, we can remove the
ori instruction.
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
Nice :)
Acked-by: Joakim Tjernlund <joakim.tjernlund@xxxxxxxxxxxx>
---
arch/powerpc/kernel/head_8xx.S | 22 ++++++++++------------
1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index ae05f28..aa45225 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -322,13 +322,12 @@ InstructionTLBMiss:
mfspr r11, SPRN_M_TW/* Get level 1 table base address */
#ifdef CONFIG_MODULES
beq 3f
- lis r11, (swapper_pg_dir-PAGE_OFFSET)@h
- ori r11, r11, (swapper_pg_dir-PAGE_OFFSET)@l
+ lis r11, (swapper_pg_dir-PAGE_OFFSET)@ha
3:
#endif
/* Insert level 1 index */
rlwimi r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
- lwz r11, 0(r11)/* Get the level 1 entry */
+ lwz r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11)/* Get the level 1 entry */
On the face of it that fragment doesn't look right when CONFIG_MODULES is undefined.
David
I'm not sure I understand what you mean.
The other part of the patch adds the following:
+ li r5, (swapper_pg_dir-PAGE_OFFSET)@l
+ sub r4, r4, r5
r4 is the value put into SPRN_M_TW, so I don't see what may be wrong.
Christophe
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/