From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC5BAC433E2 for ; Tue, 1 Sep 2020 07:46:44 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 67EC12068E for ; Tue, 1 Sep 2020 07:46:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 67EC12068E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C51FF6B0055; Tue, 1 Sep 2020 03:46:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BDDB76B005A; Tue, 1 Sep 2020 03:46:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ACA776B005C; Tue, 1 Sep 2020 03:46:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0117.hostedemail.com [216.40.44.117]) by kanga.kvack.org (Postfix) with ESMTP id 8E4B66B0055 for ; Tue, 1 Sep 2020 03:46:43 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 4ADE8180AD811 for ; Tue, 1 Sep 2020 07:46:43 +0000 (UTC) X-FDA: 77213710686.22.week51_440855f27096 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id 1C49718038E67 for ; Tue, 1 Sep 2020 07:46:43 +0000 (UTC) X-HE-Tag: week51_440855f27096 X-Filterd-Recvd-Size: 4500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Tue, 1 Sep 2020 07:46:42 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A67F51FB; Tue, 1 Sep 2020 00:46:41 -0700 (PDT) Received: from [10.163.69.134] (unknown [10.163.69.134]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 587ED3F71F; Tue, 1 Sep 2020 00:46:37 -0700 (PDT) Subject: Re: [PATCH v3 03/13] mm/debug_vm_pgtable/ppc64: Avoid setting top bits in radom value To: "Aneesh Kumar K.V" , linux-mm@kvack.org, akpm@linux-foundation.org Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, linux-snps-arc@lists.infradead.org, x86@kernel.org, linux-arch@vger.kernel.org, Gerald Schaefer , Christophe Leroy , Vineet Gupta , Mike Rapoport , Qian Cai References: <20200827080438.315345-1-aneesh.kumar@linux.ibm.com> <20200827080438.315345-4-aneesh.kumar@linux.ibm.com> <3a0b0101-e6ec-26c5-e104-5b0bb95c3e51@arm.com> <1a8abe92-032b-f60f-1df1-52bb409b35a3@linux.ibm.com> <75771782-734b-69f6-4a07-2d3542458319@arm.com> From: Anshuman Khandual Message-ID: Date: Tue, 1 Sep 2020 13:16:05 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Rspamd-Queue-Id: 1C49718038E67 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 09/01/2020 01:06 PM, Aneesh Kumar K.V wrote: > On 9/1/20 1:02 PM, Anshuman Khandual wrote: >> >> >> On 09/01/2020 11:51 AM, Aneesh Kumar K.V wrote: >>> On 9/1/20 8:45 AM, Anshuman Khandual wrote: >>>> >>>> >>>> On 08/27/2020 01:34 PM, Aneesh Kumar K.V wrote: >>>>> ppc64 use bit 62 to indicate a pte entry (_PAGE_PTE). Avoid setting= that bit in >>>>> random value. >>>>> >>>>> Signed-off-by: Aneesh Kumar K.V >>>>> --- >>>>> =C2=A0=C2=A0 mm/debug_vm_pgtable.c | 13 ++++++++++--- >>>>> =C2=A0=C2=A0 1 file changed, 10 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c >>>>> index 086309fb9b6f..bbf9df0e64c6 100644 >>>>> --- a/mm/debug_vm_pgtable.c >>>>> +++ b/mm/debug_vm_pgtable.c >>>>> @@ -44,10 +44,17 @@ >>>>> =C2=A0=C2=A0=C2=A0 * entry type. But these bits might affect the ab= ility to clear entries with >>>>> =C2=A0=C2=A0=C2=A0 * pxx_clear() because of how dynamic page table = folding works on s390. So >>>>> =C2=A0=C2=A0=C2=A0 * while loading up the entries do not change the= lower 4 bits. It does not >>>>> - * have affect any other platform. >>>>> + * have affect any other platform. Also avoid the 62nd bit on ppc6= 4 that is >>>>> + * used to mark a pte entry. >>>>> =C2=A0=C2=A0=C2=A0 */ >>>>> -#define S390_MASK_BITS=C2=A0=C2=A0=C2=A0 4 >>>>> -#define RANDOM_ORVALUE=C2=A0=C2=A0=C2=A0 GENMASK(BITS_PER_LONG - 1= , S390_MASK_BITS) >>>>> +#define S390_SKIP_MASK=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 G= ENMASK(3, 0) >>>>> +#ifdef CONFIG_PPC_BOOK3S_64 >>>>> +#define PPC64_SKIP_MASK=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 = GENMASK(62, 62) >>>>> +#else >>>>> +#define PPC64_SKIP_MASK=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 = 0x0 >>>>> +#endif >>>> >>>> Please drop the #ifdef CONFIG_PPC_BOOK3S_64 here. We already accommo= date skip >>>> bits for a s390 platform requirement and can also do so for ppc64 as= well. As >>>> mentioned before, please avoid adding any platform specific construc= ts in the >>>> test. >>>> >>> >>> >>> that is needed so that it can be built on 32 bit architectures.I did = face build errors with arch-linux >> >> Could not (#if __BITS_PER_LONG =3D=3D 32) be used instead or something= like >> that. But should be a generic conditional check identifying 32 bit arc= h >> not anything platform specific. >> >=20 > that _PAGE_PTE bit is pretty much specific to PPC BOOK3S_64.=C2=A0 Not = sure why other architectures need to bothered about ignoring bit 62. Thats okay as long it does not adversely affect other architectures, igno= ring some more bits is acceptable. Like existing S390_MASK_BITS gets ignored o= n all other platforms even if it is a s390 specific constraint. Not having plat= form specific #ifdef here, is essential.