From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-x242.google.com (mail-pa0-x242.google.com [IPv6:2607:f8b0:400e:c03::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rLXpT2drvzDqWg for ; Fri, 3 Jun 2016 15:34:25 +1000 (AEST) Received: by mail-pa0-x242.google.com with SMTP id gp3so5051862pac.2 for ; Thu, 02 Jun 2016 22:34:25 -0700 (PDT) Received: from balbir.ozlabs.ibm.com ([122.99.82.10]) by smtp.gmail.com with ESMTPSA id x19sm4729593pfi.81.2016.06.02.22.34.21 for (version=TLSv1/SSLv3 cipher=OTHER); Thu, 02 Jun 2016 22:34:22 -0700 (PDT) Subject: Re: [PATCH] powerpc/mm: use _raw variant of page table accessors To: linuxppc-dev@lists.ozlabs.org References: <1464692382-29698-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> From: Balbir Singh Message-ID: <7ba4cc59-351c-e990-97b4-c3429a0e7f34@gmail.com> Date: Fri, 3 Jun 2016 15:34:19 +1000 MIME-Version: 1.0 In-Reply-To: <1464692382-29698-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 31/05/16 20:59, Aneesh Kumar K.V wrote: > This switch few of the page table accessor to use the __raw variant > and does the cpu to big endian conversion of constants. This helps in > generating better code. > > For ex: a pgd_none(pgd) check with and without fix is listed below > > Without fix: > ------------ > 2240: 20 00 61 eb ld r27,32(r1) > /* PGD level */ > typedef struct { __be64 pgd; } pgd_t; > static inline unsigned long pgd_val(pgd_t x) > { > return be64_to_cpu(x.pgd); > > 2244: 22 00 66 78 rldicl r6,r3,32,32 > 2248: 3e 40 7d 54 rotlwi r29,r3,8 > 224c: 0e c0 7d 50 rlwimi r29,r3,24,0,7 > 2250: 3e 40 c5 54 rotlwi r5,r6,8 > 2254: 2e c4 7d 50 rlwimi r29,r3,24,16,23 > 2258: 0e c0 c5 50 rlwimi r5,r6,24,0,7 > 225c: 2e c4 c5 50 rlwimi r5,r6,24,16,23 > 2260: c6 07 bd 7b rldicr r29,r29,32,31 > 2264: 78 2b bd 7f or r29,r29,r5 > if (pgd_none(pgd)) > 2268: 00 00 bd 2f cmpdi cr7,r29,0 > 226c: 54 03 9e 41 beq cr7,25c0 <__get_user_pages_fast+0x500> > > With fix: > --------- > 2370: 20 00 61 eb ld r27,32(r1) > if (pgd_none(pgd)) > 2374: 00 00 bd 2f cmpdi cr7,r29,0 > 2378: a8 03 9e 41 beq cr7,2720 <__get_user_pages_fast+0x530> > break; > Signed-off-by: Aneesh Kumar K.V > --- Can we just save the cpu_to_be64(_PAGE_PTE) as _BE64_PAGE_PTE constant in big-endian (pgtable-be-types.h) and similar for other things. I know its not the best option, but we don't really expect these bits to change often or anymore Otherwise Acked-by: Balbir Singh