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=-10.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 81B15C433E9 for ; Thu, 3 Sep 2020 11:10:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 46EA320767 for ; Thu, 3 Sep 2020 11:10:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="iQOezLnu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727065AbgICLFm (ORCPT ); Thu, 3 Sep 2020 07:05:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726293AbgICK67 (ORCPT ); Thu, 3 Sep 2020 06:58:59 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F035C061244; Thu, 3 Sep 2020 03:58:56 -0700 (PDT) Received: from zn.tnic (p200300ec2f0d7a005419317048ee0789.dip0.t-ipconnect.de [IPv6:2003:ec:2f0d:7a00:5419:3170:48ee:789]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 901D21EC04CB; Thu, 3 Sep 2020 12:58:52 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1599130732; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=jFgR8B43svgkJTAQLtPGLdTbywp8lqxgXaF2hdYHOxI=; b=iQOezLnuceBdy6FP5f1e+/Ky22aTiU2sbh7poxpJvORa7KBnNk66Rcr39qYjUCfFei0Tdo QYChFscC2jEOZemAyZEtVFZhEtxKsPpJ/nx0yFkwjJ+Us6VUXojXdpblNYqjeZOLxzrHRm zZMkFiKoqAPbmPzSCP9I904zpWEkViY= Date: Thu, 3 Sep 2020 12:58:49 +0200 From: Borislav Petkov To: Gregor Herburger Cc: york.sun@nxp.com, mchehab@kernel.org, tony.luck@intel.com, james.morse@arm.com, rrichter@marvell.com, linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/1] edac: fsl_ddr_edac: fix expected data message Message-ID: <20200903105849.GC5462@zn.tnic> References: <20200817095302.GD549@zn.tnic> <20200827075600.22335-1-gregor.herburger@ew.tq-group.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200827075600.22335-1-gregor.herburger@ew.tq-group.com> Sender: linux-edac-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-edac@vger.kernel.org On Thu, Aug 27, 2020 at 09:56:00AM +0200, Gregor Herburger wrote: > When a correctable single bit error occurs, the driver calculates the > bad_data_bit respectively the bad_ecc_bit. If there is no error in the > corresponding data, the value becomes -1. With this the expected data > message is calculated. > > In the case of an error in the lower 32 bits or no error (-1) the right > side operand of the bit-shift becomes negative which is undefined > behavior. > > This can result in wrong and misleading messages like this: > [ 311.103794] EDAC FSL_DDR MC0: Faulty Data bit: 36 > [ 311.108490] EDAC FSL_DDR MC0: Expected Data / ECC: 0xffffffef_ffffffff / 0x80000059 > [ 311.116135] EDAC FSL_DDR MC0: Captured Data / ECC: 0xffffffff_ffffffef / 0x59 > > Fix this by only calculating the expected data where the error occurred. > > With the fix the dmesg output looks like this: > [ 311.103794] EDAC FSL_DDR MC0: Faulty Data bit: 36 > [ 311.108490] EDAC FSL_DDR MC0: Expected Data / ECC: 0xffffffef_ffffffef / 0x59 > [ 311.116135] EDAC FSL_DDR MC0: Captured Data / ECC: 0xffffffff_ffffffef / 0x59 > > Signed-off-by: Gregor Herburger > --- > drivers/edac/fsl_ddr_edac.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/edac/fsl_ddr_edac.c b/drivers/edac/fsl_ddr_edac.c > index 6d8ea226010d..4b6989cf1947 100644 > --- a/drivers/edac/fsl_ddr_edac.c > +++ b/drivers/edac/fsl_ddr_edac.c > @@ -343,9 +343,9 @@ static void fsl_mc_check(struct mem_ctl_info *mci) > > fsl_mc_printk(mci, KERN_ERR, > "Expected Data / ECC:\t%#8.8x_%08x / %#2.2x\n", > - cap_high ^ (1 << (bad_data_bit - 32)), > - cap_low ^ (1 << bad_data_bit), > - syndrome ^ (1 << bad_ecc_bit)); > + (bad_data_bit > 31) ? cap_high ^ (1 << (bad_data_bit - 32)) : cap_high, > + (bad_data_bit <= 31) ? cap_low ^ (1 << (bad_data_bit)) : cap_low, But if bad_data_bit is -1, this check above will hit and you'd still shift by -1, IINM. How about you fix it properly, clean it up and make it more readable in the process (pasting the code directly instead of a diff because a diff is less readable): if ((err_detect & DDR_EDE_SBE) && (bus_width == 64)) { sbe_ecc_decode(cap_high, cap_low, syndrome, &bad_data_bit, &bad_ecc_bit); if (bad_data_bit != -1) { if (bad_data_bit > 31) cap_high ^= 1 << (bad_data_bit - 32); else cap_low ^= 1 << bad_data_bit; fsl_mc_printk(mci, KERN_ERR, "Faulty Data bit: %d\n", bad_data_bit); fsl_mc_printk(mci, KERN_ERR, "Expected Data: %#8.8x_%08x\n", cap_high, cap_low); } if (bad_ecc_bit != -1) { fsl_mc_printk(mci, KERN_ERR, "Faulty ECC bit: %d\n", bad_ecc_bit); fsl_mc_printk(mci, KERN_ERR, "Expected ECC: %#2.2x\n", syndrome ^ (1 << bad_ecc_bit)); } } This way you print only when the respective faulty bits have been properly found and not print anything otherwise. Hmm? -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette