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Violators will be prosecuted for from ; Tue, 20 Jun 2017 04:45:59 +1000 Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay10.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v5JIjtHj2163034 for ; Tue, 20 Jun 2017 04:45:55 +1000 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v5JIjsGB026218 for ; Tue, 20 Jun 2017 04:45:55 +1000 From: "Naveen N. Rao" To: Michael Ellerman , "Aneesh Kumar K.V" Cc: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v2] powerpc64/exceptions: Refactor code to eliminate a few memory loads Date: Tue, 20 Jun 2017 00:15:45 +0530 In-Reply-To: <8760fsb902.fsf@skywalker.in.ibm.com> References: <8760fsb902.fsf@skywalker.in.ibm.com> Message-Id: <20170619184545.28848-1-naveen.n.rao@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 2017/06/19 03:21PM, Aneesh Kumar K.V wrote: > > @@ -1445,8 +1446,8 @@ do_hash_page: > > handle_page_fault: > > andis. r0,r4,DSISR_DABRMATCH@h > > bne- handle_dabr_fault > > - ld r4,_DAR(r1) > > - ld r5,_DSISR(r1) > > + mr r5,r4 > > + mr r4,r3 > > addi r3,r1,STACK_FRAME_OVERHEAD > > bl do_page_fault > > cmpdi r3,0 > > > Can we avoid that if we rearrange args of other functions calls, so that > we can use r3 and r4 as it is ? Here's a version that does that. Again, boot tested with radix and disable_radix. Thanks, Naveen - Change data_access_common() and instruction_access_common() to load the trap number in r3, DAR in r4 and DSISR in r5 (rather than in r5, r3 and r4 respectively). This change allows us to eliminate a few un-necessary memory loads and register move operations in handle_page_fault(), handle_dabr_fault() and label '77'. Signed-off-by: Naveen N. Rao --- arch/powerpc/kernel/exceptions-64s.S | 38 +++++++++++++++++------------------- 1 file changed, 18 insertions(+), 20 deletions(-) diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index b6fad9790784..4c5abe1d6f44 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -494,11 +494,11 @@ EXC_COMMON_BEGIN(data_access_common) EXCEPTION_PROLOG_COMMON(0x300, PACA_EXGEN) RECONCILE_IRQ_STATE(r10, r11) ld r12,_MSR(r1) - ld r3,PACA_EXGEN+EX_DAR(r13) - lwz r4,PACA_EXGEN+EX_DSISR(r13) - li r5,0x300 - std r3,_DAR(r1) - std r4,_DSISR(r1) + ld r4,PACA_EXGEN+EX_DAR(r13) + lwz r5,PACA_EXGEN+EX_DSISR(r13) + li r3,0x300 + std r4,_DAR(r1) + std r5,_DSISR(r1) BEGIN_MMU_FTR_SECTION b do_hash_page /* Try to handle as hpte fault */ MMU_FTR_SECTION_ELSE @@ -562,11 +562,11 @@ EXC_COMMON_BEGIN(instruction_access_common) EXCEPTION_PROLOG_COMMON(0x400, PACA_EXGEN) RECONCILE_IRQ_STATE(r10, r11) ld r12,_MSR(r1) - ld r3,_NIP(r1) - andis. r4,r12,0x5820 - li r5,0x400 - std r3,_DAR(r1) - std r4,_DSISR(r1) + ld r4,_NIP(r1) + andis. r5,r12,0x5820 + li r3,0x400 + std r4,_DAR(r1) + std r5,_DSISR(r1) BEGIN_MMU_FTR_SECTION b do_hash_page /* Try to handle as hpte fault */ MMU_FTR_SECTION_ELSE @@ -1474,7 +1474,7 @@ USE_TEXT_SECTION() .balign IFETCH_ALIGN_BYTES do_hash_page: #ifdef CONFIG_PPC_STD_MMU_64 - andis. r0,r4,0xa450 /* weird error? */ + andis. r0,r5,0xa450 /* weird error? */ bne- handle_page_fault /* if not, try to insert a HPTE */ CURRENT_THREAD_INFO(r11, r1) lwz r0,TI_PREEMPT(r11) /* If we're in an "NMI" */ @@ -1489,8 +1489,10 @@ do_hash_page: * * at return r3 = 0 for success, 1 for page fault, negative for error */ + mr r6,r5 + mr r5,r3 + mr r3,r4 mr r4,r12 - ld r6,_DSISR(r1) bl __hash_page /* build HPTE if possible */ cmpdi r3,0 /* see if __hash_page succeeded */ @@ -1500,16 +1502,15 @@ do_hash_page: /* Error */ blt- 13f - /* Reload DSISR into r4 for the DABR check below */ - ld r4,_DSISR(r1) + /* Reload DAR/DSISR for handle_page_fault */ + ld r4,_DAR(r1) + ld r5,_DSISR(r1) #endif /* CONFIG_PPC_STD_MMU_64 */ /* Here we have a page fault that hash_page can't handle. */ handle_page_fault: - andis. r0,r4,DSISR_DABRMATCH@h + andis. r0,r5,DSISR_DABRMATCH@h bne- handle_dabr_fault - ld r4,_DAR(r1) - ld r5,_DSISR(r1) addi r3,r1,STACK_FRAME_OVERHEAD bl do_page_fault cmpdi r3,0 @@ -1524,8 +1525,6 @@ handle_page_fault: /* We have a data breakpoint exception - handle it */ handle_dabr_fault: bl save_nvgprs - ld r4,_DAR(r1) - ld r5,_DSISR(r1) addi r3,r1,STACK_FRAME_OVERHEAD bl do_break 12: b ret_from_except_lite @@ -1551,7 +1550,6 @@ handle_dabr_fault: * the access, or panic if there isn't a handler. */ 77: bl save_nvgprs - mr r4,r3 addi r3,r1,STACK_FRAME_OVERHEAD li r5,SIGSEGV bl bad_page_fault -- 2.13.1