[PATCH v6 01/23] powerpc/8xx: Save r3 all the time in DTLB miss handler
From: Christophe Leroy <hidden>
Date: 2016-02-04 10:33:15
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
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 <redacted> --- v2: no change v3: no change v4: no change v5: no change v6: 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
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2.1.0