From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DA28C267F6F for ; Fri, 14 Feb 2025 17:24:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739553872; cv=none; b=WVa/TPni1W1IBOoc4N9+sTPR53ggWmyQxJ1emBjgDfW8kKXvrB6eblXvAGY1wkZTlCP+dzKgiEvGvWX2fqkamdocFSPkor/vmn4kL3qbzestMyTTyYTb+osnVypqxioFOJCBLE64x/KQAGEh9TpD3+RvPK+BicCtJ8lreKT3R/8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739553872; c=relaxed/simple; bh=Q0OEuFeXMxIl/M4HKuCdw4CJ8+gHFxwOPjKc2UbWKEc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aVb8Vxlpkv98H2udWwIteD7WDPeQk0NOUbVRiZobiLNapj8qpWxDoGugLO8lEfplgU5wx135YNkbU9jNk8hwgAUAInUK5UY2JLSyKeShu9A75PS44xpb9Nxeypo8LBtKyJvp7QG1RBzDz5RiGqllhdvtzTbtuLcIdYJixy/GiHc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4AF84C4CED1; Fri, 14 Feb 2025 17:24:27 +0000 (UTC) Date: Fri, 14 Feb 2025 17:24:24 +0000 From: Catalin Marinas To: Tong Tiangen Cc: Mark Rutland , Jonathan Cameron , Mauro Carvalho Chehab , Will Deacon , Andrew Morton , James Morse , Robin Murphy , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Michael Ellerman , Nicholas Piggin , Andrey Ryabinin , Alexander Potapenko , Christophe Leroy , "Aneesh Kumar K.V" , "Naveen N. Rao" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Madhavan Srinivasan , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, wangkefeng.wang@huawei.com, Guohanjun Subject: Re: [PATCH v13 4/5] arm64: support copy_mc_[user]_highpage() Message-ID: References: <20241209024257.3618492-1-tongtiangen@huawei.com> <20241209024257.3618492-5-tongtiangen@huawei.com> <69955002-c3b1-459d-9b42-8d07475c3fd3@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <69955002-c3b1-459d-9b42-8d07475c3fd3@huawei.com> On Fri, Feb 14, 2025 at 10:49:01AM +0800, Tong Tiangen wrote: > 在 2025/2/13 1:11, Catalin Marinas 写道: > > On Mon, Dec 09, 2024 at 10:42:56AM +0800, Tong Tiangen wrote: > > > Currently, many scenarios that can tolerate memory errors when copying page > > > have been supported in the kernel[1~5], all of which are implemented by > > > copy_mc_[user]_highpage(). arm64 should also support this mechanism. > > > > > > Due to mte, arm64 needs to have its own copy_mc_[user]_highpage() > > > architecture implementation, macros __HAVE_ARCH_COPY_MC_HIGHPAGE and > > > __HAVE_ARCH_COPY_MC_USER_HIGHPAGE have been added to control it. > > > > > > Add new helper copy_mc_page() which provide a page copy implementation with > > > hardware memory error safe. The code logic of copy_mc_page() is the same as > > > copy_page(), the main difference is that the ldp insn of copy_mc_page() > > > contains the fixup type EX_TYPE_KACCESS_ERR_ZERO_MEM_ERR, therefore, the > > > main logic is extracted to copy_page_template.S. In addition, the fixup of > > > MOPS insn is not considered at present. > > > > Could we not add the exception table entry permanently but ignore the > > exception table entry if it's not on the do_sea() path? That would save > > some code duplication. > > I'm sorry, I didn't catch your point, that the do_sea() and non do_sea() > paths use different exception tables? No, they would have the same exception table, only that we'd interpret it differently depending on whether it's a SEA error or not. Or rather ignore the exception table altogether for non-SEA errors. > My understanding is that the > exception table entry problem is fine. After all, the search is > performed only after a fault trigger. Code duplication can be solved by > extracting repeated logic to a public file. If the new exception table entries are only taken into account for SEA errors, why do we need a duplicate copy_mc_page() function generated? Isn't the copy_page() and copy_mc_page() code identical (except for the additional labels to jump to for the exception)? -- Catalin