From de1cd0790697e67b728de43e8657bb52f528bfb9 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Wed, 25 Nov 2020 07:10:52 +0000 Subject: [PATCH] powerpc/32s: Use SPRN_SPRG_SCRATCH2 in DSI prolog Use SPRN_SPRG_SCRATCH2 as an alternative scratch register in the early part of DSI prolog in order to avoid clobbering SPRN_SPRG_SCRATCH0/1 used by other prologs. The 603 doesn't like a jump from DataLoadTLBMiss to the 10 nops that are now in the beginning of DSI exception as a result of the feature section. To workaround this, add a jump as alternative. It also avoids fetching 10 nops for nothing. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/f9f8df2a2be93568768ef1ac793639f7914cf103.1606285014.git.christophe.leroy@csgroup.eu --- arch/powerpc/include/asm/reg.h | 1 + arch/powerpc/kernel/head_book3s_32.S | 24 ++++++++---------------- 2 files changed, 9 insertions(+), 16 deletions(-) diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 0978a9a0a0d1..ee645e790446 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -1204,6 +1204,7 @@ #ifdef CONFIG_PPC_BOOK3S_32 #define SPRN_SPRG_SCRATCH0 SPRN_SPRG0 #define SPRN_SPRG_SCRATCH1 SPRN_SPRG1 +#define SPRN_SPRG_SCRATCH2 SPRN_SPRG2 #define SPRN_SPRG_603_LRU SPRN_SPRG4 #endif diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S index 8cc83ce61a2b..a93c75ca8c8e 100644 --- a/arch/powerpc/kernel/head_book3s_32.S +++ b/arch/powerpc/kernel/head_book3s_32.S @@ -288,9 +288,9 @@ MachineCheck: DO_KVM 0x300 DataAccess: #ifdef CONFIG_VMAP_STACK - mtspr SPRN_SPRG_SCRATCH0,r10 - mfspr r10, SPRN_SPRG_THREAD BEGIN_MMU_FTR_SECTION + mtspr SPRN_SPRG_SCRATCH2,r10 + mfspr r10, SPRN_SPRG_THREAD stw r11, THR11(r10) mfspr r10, SPRN_DSISR mfcr r11 @@ -304,19 +304,11 @@ BEGIN_MMU_FTR_SECTION .Lhash_page_dsi_cont: mtcr r11 lwz r11, THR11(r10) -END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE) - mtspr SPRN_SPRG_SCRATCH1,r11 - mfspr r11, SPRN_DAR - stw r11, DAR(r10) - mfspr r11, SPRN_DSISR - stw r11, DSISR(r10) - mfspr r11, SPRN_SRR0 - stw r11, SRR0(r10) - mfspr r11, SPRN_SRR1 /* check whether user or kernel */ - stw r11, SRR1(r10) - mfcr r10 - andi. r11, r11, MSR_PR - + mfspr r10, SPRN_SPRG_SCRATCH2 +MMU_FTR_SECTION_ELSE + b 1f +ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE) +1: EXCEPTION_PROLOG_0 handle_dar_dsisr=1 EXCEPTION_PROLOG_1 b handle_page_fault_tramp_1 #else /* CONFIG_VMAP_STACK */ @@ -764,7 +756,7 @@ fast_hash_page_return: /* DSI */ mtcr r11 lwz r11, THR11(r10) - mfspr r10, SPRN_SPRG_SCRATCH0 + mfspr r10, SPRN_SPRG_SCRATCH2 rfi 1: /* ISI */ -- 2.20.1