lkml.org 
[lkml]   [2016]   [Feb]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v7 01/23] powerpc/8xx: Save r3 all the time in DTLB miss handler
Date
We are spending between 40 and 160 cycles with a mean of 65 cycles in
the DTLB handling routine (measured with mftbl) so make it more
simple althought it adds one instruction.
With this modification, we get three registers available at all time,
which will help with following patch.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v2: no change
v3: no change
v4: no change
v5: no change
v6: no change
v7: no change

arch/powerpc/kernel/head_8xx.S | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index e629e28..a89492e 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -385,23 +385,20 @@ InstructionTLBMiss:

. = 0x1200
DataStoreTLBMiss:
-#ifdef CONFIG_8xx_CPU6
mtspr SPRN_SPRG_SCRATCH2, r3
-#endif
EXCEPTION_PROLOG_0
- mfcr r10
+ mfcr r3

/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
- mfspr r11, SPRN_MD_EPN
- IS_KERNEL(r11, r11)
+ mfspr r10, SPRN_MD_EPN
+ IS_KERNEL(r11, r10)
mfspr r11, SPRN_M_TW /* Get level 1 table */
BRANCH_UNLESS_KERNEL(3f)
lis r11, (swapper_pg_dir-PAGE_OFFSET)@ha
3:
- mtcr r10
- mfspr r10, SPRN_MD_EPN
+ mtcr r3

/* Insert level 1 index */
rlwimi r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
@@ -453,9 +450,7 @@ DataStoreTLBMiss:
MTSPR_CPU6(SPRN_MD_RPN, r10, r3) /* Update TLB entry */

/* Restore registers */
-#ifdef CONFIG_8xx_CPU6
mfspr r3, SPRN_SPRG_SCRATCH2
-#endif
mtspr SPRN_DAR, r11 /* Tag DAR */
EXCEPTION_EPILOG_0
rfi
--
2.1.0
\
 
 \ /
  Last update: 2016-02-09 12:01    [W:0.103 / U:6.940 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site