From ae47177a6630bb8869bcec04240d9dc3024872b4 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin <npiggin@gmail.com> Date: Fri, 28 Jun 2019 15:33:21 +1000 Subject: [PATCH] powerpc/64s/exception: avoid SPR RAW scoreboard stall in real mode entry Move SPR reads ahead of writes. Real mode entry that is not a KVM guest is rare these days, but bad practice propagates. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/kernel/exceptions-64s.S | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 564a770397015..3735b9d1bb658 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -183,19 +183,19 @@ END_FTR_SECTION_NESTED(ftr,ftr,943) .endif .if \hsrr mfspr r11,SPRN_HSRR0 /* save HSRR0 */ + mfspr r12,SPRN_HSRR1 /* and HSRR1 */ + mtspr SPRN_HSRR1,r10 .else mfspr r11,SPRN_SRR0 /* save SRR0 */ + mfspr r12,SPRN_SRR1 /* and SRR1 */ + mtspr SPRN_SRR1,r10 .endif - LOAD_HANDLER(r12, \label\()) + LOAD_HANDLER(r10, \label\()) .if \hsrr - mtspr SPRN_HSRR0,r12 - mfspr r12,SPRN_HSRR1 /* and HSRR1 */ - mtspr SPRN_HSRR1,r10 + mtspr SPRN_HSRR0,r10 HRFI_TO_KERNEL .else - mtspr SPRN_SRR0,r12 - mfspr r12,SPRN_SRR1 /* and SRR1 */ - mtspr SPRN_SRR1,r10 + mtspr SPRN_SRR0,r10 RFI_TO_KERNEL .endif b . /* prevent speculative execution */ -- 2.39.5