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=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 55415C2B9F7 for ; Fri, 28 May 2021 14:35:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 37087613B4 for ; Fri, 28 May 2021 14:35:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236154AbhE1OhY (ORCPT ); Fri, 28 May 2021 10:37:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230080AbhE1OhX (ORCPT ); Fri, 28 May 2021 10:37:23 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5DC29C061574 for ; Fri, 28 May 2021 07:35:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender: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-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=R4ITbO2zQ8+lQSlzYrqLkEM0zhWRWfeQJIIZ5GiIeA8=; b=eo/JmWVlEvb6d7ZTxUyMeDveB k4g9KxD+wLtVzPfA8XlBRYVbAQYrXKqpVqeQSmBlOEOwYvIdaejXctscaVFmzPeMhz37UD3KJhVG8 ZbPll31d6s0h19rEC9xTjyEjFxigmG+CbdkzAOF8+bn5WjIrH8KbPfzyohjFNdHyp71u+cnIF09Z9 qLvgDmh0QtNdpIij93/nFNpotFyxnnBV2R8SIqQMO7u/NWCrkxXsQzI0Cv1g+sG083QQ4ihNnA/Io 8irfy1kx20apIZc15THyTauPDvsQXDLvpqyFXe/nW7TYqOxpC5ofI0VgijwM+V4jdS8Bil4QCTlGU 0aB1kHC+Q==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:44444) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lmdaU-000063-FN; Fri, 28 May 2021 15:35:46 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1lmdaS-0004mG-TV; Fri, 28 May 2021 15:35:44 +0100 Date: Fri, 28 May 2021 15:35:44 +0100 From: "Russell King (Oracle)" To: Krzysztof =?utf-8?Q?Ha=C5=82asa?= Cc: linux-arm-kernel , lkml Subject: Re: Data corruption on i.MX6 IPU in arm_copy_from_user() Message-ID: <20210528143544.GQ30436@shell.armlinux.org.uk> References: <20210526100843.GD30436@shell.armlinux.org.uk> <20210526131853.GE30436@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King (Oracle) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 28, 2021 at 12:02:52PM +0200, Krzysztof Hałasa wrote: > "Russell King (Oracle)" writes: > > > In any case, looking at the architecture reference manual, LDM is > > permitted on device and strongly ordered mappings, and the memory > > subsystem is required to decompose it into a series of 32-bit accesses. > > So, it sounds to me like there could be a hardware bug in the buses/IPU > > causing this. > > It seems so. > > I modified the kernel IPU module a bit, initialized a bunch of IPU > registers to known values (1..0xD). Results (from 1 to 13 IPU > registers) obtained with different instructions: > > readl(13 consecutive registers): CSI = 1 2 3 4 5 6 7 8 9 A B C D > 1 = register #0 and so on - readl() results are obviously correct. > > LDM1: 1 (not corrupted) > LDM2: 1 3 > LDM3: 1 3 4 > LDM4: 2 3 4 4 > LDM5: 1 3 4 5 6 > LDM6: 1 3 4 5 6 7 > LDM7: 1 3 4 5 6 7 8 > LDM8: 2 3 4 5 6 7 8 8 > LDM9: 1 3 4 5 6 7 8 9 A > LDM10: 1 3 4 5 6 7 8 9 A B > LDM11: 1 3 4 5 6 7 8 9 A B C > LDM12: 1 3 4 5 6 7 8 9 A B C D That's rather sad, and does look very much like a hardware bug. The question is what to do about it... there's Linus' "do not break userspace" edict and that's exactly what this change has done. So I suppose we're going to have to revert the change and put up with everything being slightly slower on arm32 than it otherwise would have been. That probably means we'll end up with almost every kernel tree out there carrying a revert of the revert to work around the fact that seemingly NXP broke their hardware - which itself is not a good idea. I guess we're just going to have to put up with that. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! 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Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:44444) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lmdaU-000063-FN; Fri, 28 May 2021 15:35:46 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1lmdaS-0004mG-TV; Fri, 28 May 2021 15:35:44 +0100 Date: Fri, 28 May 2021 15:35:44 +0100 From: "Russell King (Oracle)" To: Krzysztof =?utf-8?Q?Ha=C5=82asa?= Cc: linux-arm-kernel , lkml Subject: Re: Data corruption on i.MX6 IPU in arm_copy_from_user() Message-ID: <20210528143544.GQ30436@shell.armlinux.org.uk> References: <20210526100843.GD30436@shell.armlinux.org.uk> <20210526131853.GE30436@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210528_073549_500902_D28FE9EC X-CRM114-Status: GOOD ( 17.76 ) 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="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gRnJpLCBNYXkgMjgsIDIwMjEgYXQgMTI6MDI6NTJQTSArMDIwMCwgS3J6eXN6dG9mIEhhxYJh c2Egd3JvdGU6Cj4gIlJ1c3NlbGwgS2luZyAoT3JhY2xlKSIgPGxpbnV4QGFybWxpbnV4Lm9yZy51 az4gd3JpdGVzOgo+IAo+ID4gSW4gYW55IGNhc2UsIGxvb2tpbmcgYXQgdGhlIGFyY2hpdGVjdHVy ZSByZWZlcmVuY2UgbWFudWFsLCBMRE0gaXMKPiA+IHBlcm1pdHRlZCBvbiBkZXZpY2UgYW5kIHN0 cm9uZ2x5IG9yZGVyZWQgbWFwcGluZ3MsIGFuZCB0aGUgbWVtb3J5Cj4gPiBzdWJzeXN0ZW0gaXMg cmVxdWlyZWQgdG8gZGVjb21wb3NlIGl0IGludG8gYSBzZXJpZXMgb2YgMzItYml0IGFjY2Vzc2Vz Lgo+ID4gU28sIGl0IHNvdW5kcyB0byBtZSBsaWtlIHRoZXJlIGNvdWxkIGJlIGEgaGFyZHdhcmUg YnVnIGluIHRoZSBidXNlcy9JUFUKPiA+IGNhdXNpbmcgdGhpcy4KPiAKPiBJdCBzZWVtcyBzby4K PiAKPiBJIG1vZGlmaWVkIHRoZSBrZXJuZWwgSVBVIG1vZHVsZSBhIGJpdCwgaW5pdGlhbGl6ZWQg YSBidW5jaCBvZiBJUFUKPiByZWdpc3RlcnMgdG8ga25vd24gdmFsdWVzICgxLi4weEQpLiBSZXN1 bHRzIChmcm9tIDEgdG8gMTMgSVBVCj4gcmVnaXN0ZXJzKSBvYnRhaW5lZCB3aXRoIGRpZmZlcmVu dCBpbnN0cnVjdGlvbnM6Cj4gCj4gcmVhZGwoMTMgY29uc2VjdXRpdmUgcmVnaXN0ZXJzKTogQ1NJ ID0gMSAyIDMgNCA1IDYgNyA4IDkgQSBCIEMgRAo+IDEgPSByZWdpc3RlciAjMCBhbmQgc28gb24g LSByZWFkbCgpIHJlc3VsdHMgYXJlIG9idmlvdXNseSBjb3JyZWN0Lgo+IAo+IExETTE6ICAxIChu b3QgY29ycnVwdGVkKQo+IExETTI6ICAxIDMKPiBMRE0zOiAgMSAzIDQKPiBMRE00OiAgMiAzIDQg NAo+IExETTU6ICAxIDMgNCA1IDYKPiBMRE02OiAgMSAzIDQgNSA2IDcKPiBMRE03OiAgMSAzIDQg NSA2IDcgOAo+IExETTg6ICAyIDMgNCA1IDYgNyA4IDgKPiBMRE05OiAgMSAzIDQgNSA2IDcgOCA5 IEEKPiBMRE0xMDogMSAzIDQgNSA2IDcgOCA5IEEgQgo+IExETTExOiAxIDMgNCA1IDYgNyA4IDkg QSBCIEMKPiBMRE0xMjogMSAzIDQgNSA2IDcgOCA5IEEgQiBDIEQKClRoYXQncyByYXRoZXIgc2Fk LCBhbmQgZG9lcyBsb29rIHZlcnkgbXVjaCBsaWtlIGEgaGFyZHdhcmUgYnVnLgoKVGhlIHF1ZXN0 aW9uIGlzIHdoYXQgdG8gZG8gYWJvdXQgaXQuLi4gdGhlcmUncyBMaW51cycgImRvIG5vdCBicmVh awp1c2Vyc3BhY2UiIGVkaWN0IGFuZCB0aGF0J3MgZXhhY3RseSB3aGF0IHRoaXMgY2hhbmdlIGhh cyBkb25lLiBTbyBJCnN1cHBvc2Ugd2UncmUgZ29pbmcgdG8gaGF2ZSB0byByZXZlcnQgdGhlIGNo YW5nZSBhbmQgcHV0IHVwIHdpdGgKZXZlcnl0aGluZyBiZWluZyBzbGlnaHRseSBzbG93ZXIgb24g YXJtMzIgdGhhbiBpdCBvdGhlcndpc2Ugd291bGQKaGF2ZSBiZWVuLiBUaGF0IHByb2JhYmx5IG1l YW5zIHdlJ2xsIGVuZCB1cCB3aXRoIGFsbW9zdCBldmVyeSBrZXJuZWwKdHJlZSBvdXQgdGhlcmUg Y2FycnlpbmcgYSByZXZlcnQgb2YgdGhlIHJldmVydCB0byB3b3JrIGFyb3VuZCB0aGUKZmFjdCB0 aGF0IHNlZW1pbmdseSBOWFAgYnJva2UgdGhlaXIgaGFyZHdhcmUgLSB3aGljaCBpdHNlbGYgaXMg bm90CmEgZ29vZCBpZGVhLiBJIGd1ZXNzIHdlJ3JlIGp1c3QgZ29pbmcgdG8gaGF2ZSB0byBwdXQg dXAgd2l0aCB0aGF0LgoKLS0gClJNSydzIFBhdGNoIHN5c3RlbTogaHR0cHM6Ly93d3cuYXJtbGlu dXgub3JnLnVrL2RldmVsb3Blci9wYXRjaGVzLwpGVFRQIGlzIGhlcmUhIDQwTWJwcyBkb3duIDEw TWJwcyB1cC4gRGVjZW50IGNvbm5lY3Rpdml0eSBhdCBsYXN0IQoKX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX18KbGludXgtYXJtLWtlcm5lbCBtYWlsaW5nIGxp c3QKbGludXgtYXJtLWtlcm5lbEBsaXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5pbmZy YWRlYWQub3JnL21haWxtYW4vbGlzdGluZm8vbGludXgtYXJtLWtlcm5lbAo=