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 41FEAC77B7E for ; Mon, 29 May 2023 08:37:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To: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=wSYHLHgXq3qAOa+Z0WspZaPPqvQas44Mj34tPczDtEM=; b=eipKAW4T8hPmP0 yLsaKYIWOq5Yzi2NhrbO+bRJYkkVU6xqwCejeXDEeTyVz+8vfigM68xN/5+xIqcYsXJAQEUScigbs UaHTkKzrB7vuxTYM6QaSV8sDszK8G4orsn+iyh+7OPhswOF+BPyeAmi7dNNEaQIQC5Tf6tloZRLC5 RVqCdn14sGoMhp0IHCHKT9GrMMuKjlfxLzTgEibBAn1czmchec3gkGasA4WC4pII320u3gPOerOFy ZXsE6qs9c3g2TByG32yMq67uEAlmIcHU2lM5rynz0jr2WvEQudNCaFcUJtHIvuzdksZLuiUrg2mzW 3dZSwe0toSFcKBouXc0w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q3YNh-009ji8-2x; Mon, 29 May 2023 08:37:33 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q3YNe-009jhF-2U for linux-arm-kernel@lists.infradead.org; Mon, 29 May 2023 08:37:32 +0000 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 74852611F8; Mon, 29 May 2023 08:37:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 70462C433EF; Mon, 29 May 2023 08:37:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1685349448; bh=CCUPziSkCzOqPqywzNs2qZ9qhrttdWy8eSJClG82XbI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NH/TNk+FaUKdryMnaUVwo560jZ2kmTBlw4OUah1VnPKtBqjxmavJqh7kjdIAkHuU5 dA2fN0+JEwl1NvmDMjm87muL9Ya/wsgdzCT1oV6+nwCzz5Os5pezyf1tRDi7uTpzP3 A/+DX+3mYdjq91TkjDPKjk7Z+6Umu/808sLJZkoo= Date: Mon, 29 May 2023 09:37:26 +0100 From: Greg KH To: Jiri Olsa Cc: stable@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Masami Hiramatsu , Tsahee Zidenberg , Andrii Nakryiko , Christoph Hellwig , Daniel Borkmann , Thomas Gleixner , =?iso-8859-1?Q?Mah=E9?= Tardy , linux-arm-kernel@lists.infradead.org Subject: Re: [RFC PATCH stable 5.4 0/8] bpf: Fix bpf_probe_read/bpf_probe_read_str helpers Message-ID: <2023052947-jubilance-driven-31d8@gregkh> References: <20230522203352.738576-1-jolsa@kernel.org> <2023052646-magnetize-equate-2b24@gregkh> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230529_013730_877881_8F1ACC69 X-CRM114-Status: GOOD ( 27.52 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, May 28, 2023 at 10:02:49PM +0200, Jiri Olsa wrote: > On Fri, May 26, 2023 at 07:54:17PM +0100, Greg KH wrote: > > On Mon, May 22, 2023 at 10:33:44PM +0200, Jiri Olsa wrote: > > > hi, > > > we see broken access to user space with bpf_probe_read/bpf_probe_read_str > > > helpers on arm64 with 5.4 kernel. The problem is that both helpers try to > > > read user memory by calling probe_kernel_read, which seems to work on x86 > > > but fails on arm64. > > > > Has this ever worked on arm64 for the 5.4 kernel tree? If not, it's not > > really a regression, and so, why not use a newer kernel that has this > > new feature added to it there? > > > > In other words, what requires you to use the 5.4.y tree and requires > > feature parity across architectures? > > we have a customer running ok on x86 v5.4, but arm64 is broken with > the same bpf/user space code Again why can they not use a newer kernel version? What forces this customer to be stuck with a specific kernel version that spans different processor types? > upgrade is an option of course, but it's not a big change and we can > have 5.4 working on arm64 as well For loads of other reasons, I'd recommend 5.15 or newer for arm64, so why not use that? > I can send out the change that will be closer to upstream changes, > if that's a concern.. with adding the new probe helpers, which I > guess is not a problem, because it does not change current API You are trying to add features to a stable kernel that are not regression fixes, which is something that we generally do not accept into stable kernels. thnaks, greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel