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=-2.2 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,USER_AGENT_SANE_1 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 7E006C47258 for ; Tue, 5 May 2020 12:16:07 +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 4A473206B8 for ; Tue, 5 May 2020 12:16:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="dkgSo98C" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4A473206B8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de 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=arh8i0F462NK4LTmp/EpYrojluvR7VyqNdB6JfjepEs=; b=dkgSo98C2ArWlR zR6yp4BhlC85CfYK/wXp9mqC+V/5H4IJ7VON5g1oyxpD9lQMY9FcGyKpT9xyCW8hhvnD0X4Z7xnxg MKNaHioggFddIV7u1DC1JCnuEwkHhvMKXv/V4zJvIIwjmwoB8BOlCptvPaJBAb5iN6L012P3QzY+T FfRsdA4JdkCohcyWdYIBgcUKZ9KfLB4ABCFqHs3MJyRvA2MYBplmdXqC0+hNVQ9SNR1AhPjQVHr2K 6seclKCQvfKgcYj4EC9GMJRosXRiDNcwObQes2R2djfHas0G6Qe7u5eBSXBn7SrH23nCczJrwXZ3h 6PikXBeOiJ1CUcIXGQpQ==; 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 1jVwUV-00007b-T3; Tue, 05 May 2020 12:16:03 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jVwUS-000072-WA for linux-arm-kernel@lists.infradead.org; Tue, 05 May 2020 12:16:02 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 68BE668C4E; Tue, 5 May 2020 14:15:57 +0200 (CEST) Date: Tue, 5 May 2020 14:15:57 +0200 From: Christoph Hellwig To: Jann Horn Subject: Re: [PATCH v2 1/5] binfmt_elf_fdpic: Stop using dump_emit() on user pointers on !MMU Message-ID: <20200505121557.GA24052@lst.de> References: <20200429214954.44866-1-jannh@google.com> <20200429214954.44866-2-jannh@google.com> <20200505104805.GA17400@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200505_051601_183443_DCBA14D6 X-CRM114-Status: GOOD ( 15.56 ) 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: Rich Felker , linux-c6x-dev@linux-c6x.org, Yoshinori Sato , Linux-sh list , kernel list , Oleg Nesterov , Linux-MM , Alexander Viro , Mark Salter , linux-fsdevel , Russell King , Andrew Morton , Aurelien Jacquiot , Linus Torvalds , Christoph Hellwig , Linux ARM , "Eric W . Biederman" 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 Tue, May 05, 2020 at 01:42:12PM +0200, Jann Horn wrote: > On Tue, May 5, 2020 at 12:48 PM Christoph Hellwig wrote: > > On Wed, Apr 29, 2020 at 11:49:50PM +0200, Jann Horn wrote: > > > dump_emit() is for kernel pointers, and VMAs describe userspace memory. > > > Let's be tidy here and avoid accessing userspace pointers under KERNEL_DS, > > > even if it probably doesn't matter much on !MMU systems - especially given > > > that it looks like we can just use the same get_dump_page() as on MMU if > > > we move it out of the CONFIG_MMU block. > > > > Looks sensible. Did you get a chance to test this with a nommu setup? > > Nope. Do you happen to have a recommendation for a convenient > environment I can use with QEMU, or something like that? I'm guessing > that just running a standard armel Debian userspace with a !mmu ARM > kernel wouldn't work so well? Nommu generally needs special userspace either using uclibc-ng or musl. When I did the RISC-V nommu work I used buildroot for my root file systems. We haven't gotten elffdpic to work on RISC-V yet, so I can't use that setup for testing, but it should support ARM as well. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel