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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4D4FAEB64D8 for ; Tue, 13 Jun 2023 22:08:53 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=HyA2VS9k; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4QgjPb3MWBz3bPN for ; Wed, 14 Jun 2023 08:08:51 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=HyA2VS9k; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=139.178.84.217; helo=dfw.source.kernel.org; envelope-from=rppt@kernel.org; receiver=lists.ozlabs.org) Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4QgLDK6NS2z2yTN for ; Tue, 13 Jun 2023 17:44:33 +1000 (AEST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5069B6132D; Tue, 13 Jun 2023 07:44:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E078FC433D2; Tue, 13 Jun 2023 07:44:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686642270; bh=ez0I+RKRhMdZt82NML91fPb7fzRC4/NkCFA3IdK3cEg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HyA2VS9kwVTQsYOWOuof1Z4qJ92ct0+rpQ0B5SIAzOL2Mz6wp6NoYwA7DcLYOqzj9 Q8Z9RGOQt5lsRA8Nc33tC8G7SiwN9ipBSdD03bBdhpX4MycI3Vh7vOT7ypJVtsouWv 8Bsg5dlRSFLhnsq+PWCSJc5VolYLva+SeDgrT92N096TEl0/uLmsJvVPLGz9OK3/dz OYm6tEkeVT/cDyaIgk5UyxE5b/W7hyDcldGwNesOYI9EZOqwD7xGIveZKNt/lp9izm uoBjmwxoGZjGvj7XWF9lQv7iNjjhyG9sIxFni/WcE8h+xW9r48P7ifrawWGz2rEEWN FKciDs53eQHeQ== Date: Tue, 13 Jun 2023 10:43:47 +0300 From: Mike Rapoport To: Rick Edgecombe Subject: Re: [PATCH v9 01/42] mm: Rename arch pte_mkwrite()'s to pte_mkwrite_novma() Message-ID: <20230613074347.GR52412@kernel.org> References: <20230613001108.3040476-1-rick.p.edgecombe@intel.com> <20230613001108.3040476-2-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230613001108.3040476-2-rick.p.edgecombe@intel.com> X-Mailman-Approved-At: Wed, 14 Jun 2023 08:08:02 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kcc@google.com, linux-ia64@vger.kernel.org, loongarch@lists.linux.dev, linux-doc@vger.kernel.org, Peter Zijlstra , Dave Hansen , david@redhat.com, eranian@google.com, Oleg Nesterov , linux-mm@kvack.org, linux-csky@vger.kernel.org, Pavel Machek , "H . Peter Anvin" , sparclinux@vger.kernel.org, linux-riscv@lists.infradead.org, Nadav Amit , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, dethoma@microsoft.com, Linus Torvalds , Jonathan Corbet , linux-sh@vger.kernel.org, linux-hexagon@vger.kernel.org, x86@kernel.org, Eugene Syromiatnikov , jamorris@linux.microsoft.com, szabolcs.nagy@arm.com, Ingo Molnar , linux-snps-arc@lists.infradead.org, "H . J . Lu" , Kees Cook , Arnd Bergmann , Jann Horn , linux-alp ha@vger.kernel.org, linux-um@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-mips@vger.kernel.org, linux-m68k@lists.linux-m68k.org, broonie@kernel.org, Borislav Petkov , Andy Lutomirski , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, debug@rivosinc.com, Florian Weimer , Michal Simek , John Allen , linux-parisc@vger.kernel.org, Weijiang Yang , linux-api@vger.kernel.org, christina.schimpe@intel.com, Randy Dunlap , linux-kernel@vger.kernel.org, Cyrill Gorcunov , Dinh Nguyen , openrisc@lists.librecores.org, Andrew.Cooper3@citrix.com, akpm@linux-foundation.org, torvalds@linux-foundation.org, "Kirill A . Shutemov" , Mike Kravetz Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, Jun 12, 2023 at 05:10:27PM -0700, Rick Edgecombe wrote: > The x86 Shadow stack feature includes a new type of memory called shadow > stack. This shadow stack memory has some unusual properties, which requires > some core mm changes to function properly. > > One of these unusual properties is that shadow stack memory is writable, > but only in limited ways. These limits are applied via a specific PTE > bit combination. Nevertheless, the memory is writable, and core mm code > will need to apply the writable permissions in the typical paths that > call pte_mkwrite(). Future patches will make pte_mkwrite() take a VMA, so > that the x86 implementation of it can know whether to create regular > writable memory or shadow stack memory. Nit: ^ mapping? > But there are a couple of challenges to this. Modifying the signatures of > each arch pte_mkwrite() implementation would be error prone because some > are generated with macros and would need to be re-implemented. Also, some > pte_mkwrite() callers operate on kernel memory without a VMA. > > So this can be done in a three step process. First pte_mkwrite() can be > renamed to pte_mkwrite_novma() in each arch, with a generic pte_mkwrite() > added that just calls pte_mkwrite_novma(). Next callers without a VMA can > be moved to pte_mkwrite_novma(). And lastly, pte_mkwrite() and all callers > can be changed to take/pass a VMA. > > Start the process by renaming pte_mkwrite() to pte_mkwrite_novma() and > adding the pte_mkwrite() wrapper in linux/pgtable.h. Apply the same > pattern for pmd_mkwrite(). Since not all archs have a pmd_mkwrite_novma(), > create a new arch config HAS_HUGE_PAGE that can be used to tell if > pmd_mkwrite() should be defined. Otherwise in the !HAS_HUGE_PAGE cases the > compiler would not be able to find pmd_mkwrite_novma(). > > No functional change. > > Cc: linux-doc@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Cc: linux-alpha@vger.kernel.org > Cc: linux-snps-arc@lists.infradead.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-csky@vger.kernel.org > Cc: linux-hexagon@vger.kernel.org > Cc: linux-ia64@vger.kernel.org > Cc: loongarch@lists.linux.dev > Cc: linux-m68k@lists.linux-m68k.org > Cc: Michal Simek > Cc: Dinh Nguyen > Cc: linux-mips@vger.kernel.org > Cc: openrisc@lists.librecores.org > Cc: linux-parisc@vger.kernel.org > Cc: linuxppc-dev@lists.ozlabs.org > Cc: linux-riscv@lists.infradead.org > Cc: linux-s390@vger.kernel.org > Cc: linux-sh@vger.kernel.org > Cc: sparclinux@vger.kernel.org > Cc: linux-um@lists.infradead.org > Cc: linux-arch@vger.kernel.org > Cc: linux-mm@kvack.org > Suggested-by: Linus Torvalds > Signed-off-by: Rick Edgecombe > Link: https://lore.kernel.org/lkml/CAHk-=wiZjSu7c9sFYZb3q04108stgHff2wfbokGCCgW7riz+8Q@mail.gmail.com/ Reviewed-by: Mike Rapoport (IBM) -- Sincerely yours, Mike.