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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 D13CACA5FC5 for ; Wed, 30 Sep 2026 13:30:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=nvaGfG5po310924tWdFlbGKV3vnFi2Daw5X+Y5l+SdE=; b=kw0ZJJXCweVFy01IvToAcE6Phm ChmL6FS7n+/izVGHv1nt/Jo7l/hTbdsP2bGUDQRhzTJxP9IlcoS10G08HvI18XD+0/kQR3kra22+c DnM4TeBy0zpMYzQiTmZ94DoUAD8yc0C7eD9eCaCN89cDCmRHokwDwRiL5u7a3Y75h/O2nTU0BhRGf eAeilkx0MK87MGxhey3FMSDH7bDxolKt6SFFQgnBzZfAzJ5Wu2Se85Jr+W/0gW5PTw+Z5TTx5RicY olxSpPKq4iS54GqFhbPZCA3pMQ0wczR4kF/k/LWGuDgB1mAiZBUZI/wn++00YnNv2gjfu8GPmjANB XolTg8jw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xBuNd-000000068Fs-496h; Wed, 30 Sep 2026 13:29:53 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xBuNc-000000068F7-0iA1 for linux-arm-kernel@lists.infradead.org; Wed, 30 Sep 2026 13:29:52 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 8F06B43A5C; Wed, 30 Sep 2026 13:29:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A35061F000FF; Wed, 30 Sep 2026 13:29:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790774991; bh=nvaGfG5po310924tWdFlbGKV3vnFi2Daw5X+Y5l+SdE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=BImizp0pcOo86qSBUaEKZtafbOxXv4ougbDwjERwnQ6CKlE/QwoMHh4eItftccdfP pHXj+IRllK8sWCWTmM9Hsrx7ZWITsOBfDCvBe0ArJGVR+8/VdYoYxXVljSS4v6HfTp RqU6zJwI7EJhiPZZD3qDdlbUqkuAIDVR67kNnkhceDYvdRSnVY5rbuLsfNm3j1BloA nc+WvnMpPlu+d3R00bvlMKqcQ5QkVFXY54hHWF8COxldFwQBj3HbVlLFeWhQiKGY/e 2qi1HHOt7mxYT111BgykY6aHThWeIk9VfCUwfnLYgzE/ebSuWoteMpuMXK4Eh9Yt2b zJT3n4h1v/TMw== Date: Wed, 30 Sep 2026 14:29:46 +0100 From: Will Deacon To: =?iso-8859-1?Q?Andr=E9?= Almeida Cc: Catalin Marinas , Billy Laws , Mark Rutland , Mark Brown , Ryan Houdek , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel-dev@igalia.com Subject: Re: [RFC PATCH v3 1/1] arch: arm64: Implement unaligned atomic emulation Message-ID: References: <20260930020138.2377090-1-andrealmeid@igalia.com> <20260930020138.2377090-2-andrealmeid@igalia.com> <00227dc1-e01c-4de8-b3e3-3cd8de74cba9@igalia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <00227dc1-e01c-4de8-b3e3-3cd8de74cba9@igalia.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Sep 30, 2026 at 07:29:22AM -0300, André Almeida wrote: > Em 30/09/2026 04:48, Will Deacon escreveu: > > On Tue, Sep 29, 2026 at 11:01:38PM -0300, André Almeida wrote: > > > Implement support for emulating unaligned atomic operations on arm64. > > > User applications that wish to enable support for this should use the > > > pctrl() flag `PR_ARM64_UNALIGN_ATOMIC_EMULATE`. > > > > > > Signed-off-by: André Almeida > > > --- > > > arch/arm64/Kconfig | 6 + > > > arch/arm64/include/asm/exception.h | 1 + > > > arch/arm64/include/asm/processor.h | 5 + > > > arch/arm64/include/asm/rwonce.h | 14 +- > > > arch/arm64/include/asm/thread_info.h | 1 + > > > arch/arm64/kernel/Makefile | 3 +- > > > arch/arm64/kernel/process.c | 15 + > > > arch/arm64/kernel/unaligned_atomic.c | 521 +++++++++++++++++++++++++++ > > > arch/arm64/mm/fault.c | 10 + > > > include/uapi/linux/prctl.h | 5 + > > > kernel/sys.c | 7 +- > > > 11 files changed, 579 insertions(+), 9 deletions(-) > > > create mode 100644 arch/arm64/kernel/unaligned_atomic.c > > > > No. > > > > I already explained to you why this doesn't work: > > > > https://lore.kernel.org/r/aV1YnOetDHhKe4hz@willie-the-truck > > Indeed, last time you raised some points, and then Ryan replied them. Is > there any specific point that doesn't work? I couldn't find a reply for > Ryan's answers: > > https://lore.kernel.org/all/CABnRqDf5EQUoXu=pJ6mj4-JfwAzEfcAE2cYrNzJANFycx7cMUA@mail.gmail.com/ So rather than get involved in the discussion, you did nothing for almost a year and then resent the exact same patch? Why? I don't think the implementation is correct and I don't think we should be emulating this either. I hope I made that clear last year. Ryan thinks it's "fine" due to the locking, but I don't see how that helps with the example I gave. You are apparently the author of this code, so you need to get involved in the discussion if you want to move the needle. Will