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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 0EBBCC2B9F7 for ; Wed, 26 May 2021 12:29:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D6DBE613CC for ; Wed, 26 May 2021 12:29:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233514AbhEZMal (ORCPT ); Wed, 26 May 2021 08:30:41 -0400 Received: from ni.piap.pl ([195.187.100.5]:52350 "EHLO ni.piap.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232829AbhEZMaj (ORCPT ); Wed, 26 May 2021 08:30:39 -0400 Received: from t19.piap.pl (OSB1819.piap.pl [10.0.9.19]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ni.piap.pl (Postfix) with ESMTPSA id 7B9794441CC; Wed, 26 May 2021 14:29:07 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 ni.piap.pl 7B9794441CC DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=piap.pl; s=mail; t=1622032147; bh=gCJ0rIGLjNAWVrx9kpX2mzO+HVS/Mtj4phJXnJzE1og=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=K2cPDuyonovbOg74Sk9BWLn5l9jsYqv2Jq40kxJwaG/WoJ22a+s+S9aF43tuZk4d1 m8A74B0JejkJjC6OvKXGxO0whj4x9mgV9zYGrl5PHrhw/s+FnafuGPMKZtkGfMfw3a m/5rml4r7zvVjE4e2AXCdbEXX3/CfWxjhhaWZP9s= From: =?utf-8?Q?Krzysztof_Ha=C5=82asa?= To: "Russell King (Oracle)" Cc: linux-arm-kernel , lkml Subject: Re: Data corruption on i.MX6 IPU in arm_copy_from_user() References: <20210526100843.GD30436@shell.armlinux.org.uk> Sender: khalasa@piap.pl Date: Wed, 26 May 2021 14:29:07 +0200 In-Reply-To: <20210526100843.GD30436@shell.armlinux.org.uk> (Russell King's message of "Wed, 26 May 2021 11:08:44 +0100") Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-KLMS-Rule-ID: 4 X-KLMS-Message-Action: skipped X-KLMS-AntiSpam-Status: not scanned, whitelist X-KLMS-AntiPhishing: not scanned, whitelist X-KLMS-AntiVirus: Kaspersky Security for Linux Mail Server, version 8.0.3.30, not scanned, whitelist Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "Russell King (Oracle)" writes: > Surely someone is not using copy_*_user() to copy data from userspace > direct to MMIO space... that would be crazy. No, it's the other way around: reading MMIO mapped to userspace (mmap on /dev/mem) and copying it to simple kernel buffer (e.g. pipe buffer). I.e., the MMIO is the userspace here (thus copy_from_user()). --=20 Krzysztof Ha=C5=82asa Sie=C4=87 Badawcza =C5=81ukasiewicz Przemys=C5=82owy Instytut Automatyki i Pomiar=C3=B3w PIAP Al. Jerozolimskie 202, 02-486 Warszawa