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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 D300DC4320A for ; Sat, 21 Aug 2021 16:27:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3D7DC6108B for ; Sat, 21 Aug 2021 16:27:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 3D7DC6108B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=alien8.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 8AC3C6B006C; Sat, 21 Aug 2021 12:27:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 85BFB6B0072; Sat, 21 Aug 2021 12:27:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 74A418D0001; Sat, 21 Aug 2021 12:27:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0198.hostedemail.com [216.40.44.198]) by kanga.kvack.org (Postfix) with ESMTP id 5966A6B006C for ; Sat, 21 Aug 2021 12:27:35 -0400 (EDT) Received: from smtpin36.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id D3AC3182BF516 for ; Sat, 21 Aug 2021 16:27:34 +0000 (UTC) X-FDA: 78499618428.36.C10AC6A Received: from mail.skyhub.de (unknown [5.9.137.197]) by imf23.hostedemail.com (Postfix) with ESMTP id 7D4D190000A6 for ; Sat, 21 Aug 2021 16:27:26 +0000 (UTC) Received: from zn.tnic (p200300ec2f24ae00bda189edbc359330.dip0.t-ipconnect.de [IPv6:2003:ec:2f24:ae00:bda1:89ed:bc35:9330]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 34D691EC0236; Sat, 21 Aug 2021 18:26:51 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1629563211; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=0X9mARlIoI2YRPMAIxP7vYnoH77rVjJv4iOG9yPzbYo=; b=beFqjaCUR9g7x13v6kfDTVD7cJJ5lUQ02pYgQqgQQW+Dx4bC8R5jG/1T5ZRYq6EDDb5+xa bw0pZXorCmCVKLFYYdtk53S2JVodDz0MBX3kC+g2G6IQ6GLmr+H4J/r4sw2B7gBfwwqSDs rfWLAA2/wQdC4xwNfxLmtKRs7WN/+Sw= Date: Sat, 21 Aug 2021 18:27:29 +0200 From: Borislav Petkov To: "Yu, Yu-cheng" Cc: Andy Lutomirski , "luto@amacapital.net" , the arch/x86 maintainers , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Linux Kernel Mailing List , linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, Linux API , Arnd Bergmann , Balbir Singh , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , "Peter Zijlstra (Intel)" , Randy Dunlap , "Shankar, Ravi V" , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang , Rick P Edgecombe , "Kirill A. Shutemov" Subject: Re: [PATCH v28 09/32] x86/mm: Introduce _PAGE_COW Message-ID: References: <1A27F5DF-477B-45B7-AD33-CC68D9B7CB89@amacapital.net> <490345b6-3e3d-4692-8162-85dcb71434c9@www.fastmail.com> <9a2b91ea-6a07-b7c8-24ac-3a15f62fbb7c@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <9a2b91ea-6a07-b7c8-24ac-3a15f62fbb7c@intel.com> X-Rspamd-Queue-Id: 7D4D190000A6 Authentication-Results: imf23.hostedemail.com; dkim=temperror ("DNS error when getting key") header.d=alien8.de header.s=dkim header.b=beFqjaCU; dmarc=temperror reason="server fail" header.from=alien8.de (policy=temperror); spf=temperror (imf23.hostedemail.com: error in processing during lookup of bp@alien8.de: DNS error) smtp.mailfrom=bp@alien8.de X-Rspamd-Server: rspam01 X-Stat-Signature: kzew34rfggbfiuqmkqy65785agdnt4xj X-HE-Tag: 1629563246-25984 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 Wed, Aug 18, 2021 at 09:38:30AM -0700, Yu, Yu-cheng wrote: > We can visualize the type of a mm area by looking at vma->vm_flags, e.g. visualize? > maybe_mkwrite(), and PTE macros as lower-level operatives. These two have > some relations but not one-to-one. Note that a PTE in a writable area is > not always pte_write(). > > I have considered and implemented a shadow stack PTE either pte_write() or > not. Making shadow stack as pte_write() results in less arch_* macros and > less confusion in copy-on-write code. That is one more thing to consider. Ok, even though I'm still not 100% convinced by both amluto's and your arguments. Let's try it and see what happens... -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette