From 913a6b3d10d85a032eff2f31254c35e0976f5e32 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Tue, 9 Feb 2016 17:07:48 +0100 Subject: [PATCH] powerpc/8xx: Save r3 all the time in DTLB miss handler 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 Signed-off-by: Scott Wood --- 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 -- 2.7.4