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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 08CC3C433DF for ; Thu, 11 Jun 2020 12:47:21 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id CB8A320747 for ; Thu, 11 Jun 2020 12:47:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="lOg3YbU/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CB8A320747 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject: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=3CuowfwBXqn7Ao0lfXLkz1CSoL+cOsjIAoWOThx1FiE=; b=lOg3YbU/VErfGX C4X9fPXg0G9qp8WJppssGb7j/JuqvrrjT9hQSoWvGRJFLunjWZIkpfjNJ8ANOVH2XZsC6l6wZv/i8 zGyAq0DeQO6fEMYq9CtQHOjPcnVWFKInKzAoIT6zeN+fmeb/tBoNfIloz5f+484Bn0IsG7O6lp06E flAt+IXlLARomhfNDQa3s6gb5ZPJvUadc18vpYPPqvddFladpePy8rtdARuAYwDqy20c2z0iwRTmY q1v0Ixtrx00BbsZOUoJGsoAgVgjLwQ0GzgM0NGIRghKF67Edl8CCVtvbaqQV/ZaMX1HpD8LbJWmxX uPMBc0vZ7LOD54cP7KiQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jjMc4-0005TX-EO; Thu, 11 Jun 2020 12:47:20 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jjMc0-0005So-Ao for linux-arm-kernel@lists.infradead.org; Thu, 11 Jun 2020 12:47:17 +0000 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 B16721FB; Thu, 11 Jun 2020 05:47:12 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [10.57.13.172]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 168F73F66F; Thu, 11 Jun 2020 05:47:06 -0700 (PDT) Date: Thu, 11 Jun 2020 13:47:04 +0100 From: Mark Rutland To: ??? Subject: Re: [PATCH] arm64: fpsimd: Added API to manage fpsimd state inside kernel Message-ID: <20200611124704.GC53118@C02TD0UTHF1T.local> References: <20200605073052.23044-1-wooy88.kim@samsung.com> <20200605103705.GD85498@C02TD0UTHF1T.local> <20200608103340.GA31466@arm.com> <000001d63fd1$23430d80$69c92880$@samsung.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <000001d63fd1$23430d80$69c92880$@samsung.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200611_054716_412847_24550E65 X-CRM114-Status: GOOD ( 14.57 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: 'Catalin Marinas' , 'Bhupesh Sharma' , 'Julien Grall' , 'Vincenzo Frascino' , 'Will Deacon' , yhwan.joo@samsung.com, 'Anisse Astier' , 'Marc Zyngier' , 'Allison Randal' , 'Sanghoon Lee' , jihun.kim@samsung.com, 'Dave Martin' , 'Kees Cook' , 'Suzuki K Poulose' , 'Wooki Min' , 'Kristina Martsenko' , 'Jeongtae Park' , 'Thomas Gleixner' , linux-arm-kernel@lists.infradead.org, 'Steve Capper' , 'Greg Kroah-Hartman' , linux-kernel@vger.kernel.org, 'James Morse' , 'Sudeep Holla' , dh.han@samsung.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jun 11, 2020 at 06:17:32PM +0900, ??? wrote: > > On Fri, Jun 05, 2020 at 11:37:05AM +0100, Mark Rutland wrote: > > > Please introduce the problem you are trying to solve in more detail. > > > We already have kernel_neon_{begin,end}() for kernel-mode NEON; why is > > > that not sufficient for your needs? Please answer this before > > > considering other details. > > > > > > What do you want to use this for? > > > Ack, this looks supicious. Can you explain why your usecase _requires_ > > FPSIMD in hardirq context? > > > > For now, these functions are strictly for EFI use only and should never be > > used by modules. > > I am in charge of camera driver development in Samsung S.LSI division. > > In order to guarantee real time processing > such as Camera 3A algorithm in current or ongoing projects, > prebuilt binary is loaded and used in kernel space, rather than user space. > Because the binary is built with other standard library which could use > FPSIMD register, > kernel API should keep the original FPSIMD state for other user tasks. > It is mostly used for internal kernel operation including hardirq context. > (ex> hardIRQ context, kernel API called by user, kernel task) That sounds incredibly dodgy to me, both from a correctness perspective and a licensing perspective. Upstream doesn't support out-of-tree modules, nor does upstream support binary blobs within the kernel, so the above cannot justify this change to the kernel. If you wish to do such processing within the kernel, I think you'll need to post a more complete in-tree solution for inclusion in mainline. However, I suspect that it will be difficult to justify NEON in hardirq context given preempt rt and friends. Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel