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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 13875C433B4 for ; Fri, 9 Apr 2021 15:34:55 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 5BAF161028 for ; Fri, 9 Apr 2021 15:34:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5BAF161028 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bugzilla.kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4FH2Hw644Vz3c1h for ; Sat, 10 Apr 2021 01:34:52 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=fL1CubXD; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=bugzilla.kernel.org (client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=bugzilla-daemon@bugzilla.kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=fL1CubXD; dkim-atps=neutral Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4FH2HR580tz2yYZ for ; Sat, 10 Apr 2021 01:34:27 +1000 (AEST) Received: by mail.kernel.org (Postfix) with ESMTPS id CF52261028 for ; Fri, 9 Apr 2021 15:34:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1617982464; bh=f4TkVWHuivk8mFbzPr2ht1owFI1UWtlCGEOLOe/8IT0=; h=From:To:Subject:Date:From; b=fL1CubXDxVTFF/GXjHSJpHCYq30KFIRizNr8f4EQuj1JQHhzUOyqsPt6mS8M34eOO f51Q6tX5jbcqoz7KFk1Doy4qLDEk+oPE9B/29AgrF1N9HWHW2fWWjoIhrkxNgheFZ4 0gJH54SFdVzTMcx1emQZWjT3iYYnWrKxTAHuSiO4K8qtJzfHWPf3fLVAcGveU4w+gi HzetaUwQ1/T6irovGzqTzkoyhOXDb06kpoE5h4XgROOKAyt7oklMQ8Q32TyZiz28zr xGRR5J5hHSnRccHFkd2RMn/+OzOyx6kNW18ChYqhmYWaKxDTLoBFmchkBdTu2/3QjJ LmwtVe5G+eelA== From: bugzilla-daemon@bugzilla.kernel.org To: linuxppc-dev@lists.ozlabs.org Subject: [Bug 212631] New: Misaligned floating point loads and store occasionally fail Date: Fri, 09 Apr 2021 15:34:24 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: AssignedTo platform_ppc-32@kernel-bugs.osdl.org X-Bugzilla-Product: Platform Specific/Hardware X-Bugzilla-Component: PPC-32 X-Bugzilla-Version: 2.5 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: trevor_davenport@selinc.com X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P1 X-Bugzilla-Assigned-To: platform_ppc-32@kernel-bugs.osdl.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version cf_kernel_version rep_platform op_sys cf_tree bug_status bug_severity priority component assigned_to reporter cf_regression attachments.created Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" https://bugzilla.kernel.org/show_bug.cgi?id=3D212631 Bug ID: 212631 Summary: Misaligned floating point loads and store occasionally fail Product: Platform Specific/Hardware Version: 2.5 Kernel Version: 5.4.110 Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: PPC-32 Assignee: platform_ppc-32@kernel-bugs.osdl.org Reporter: trevor_davenport@selinc.com Regression: No Created attachment 296311 --> https://bugzilla.kernel.org/attachment.cgi?id=3D296311&action=3Dedit Floating point load test program On a 32-bit PPC, e300c1 CPU, I am occasionally seeing misaligned floating p= oint loads/store occasionally fail. It appears to happen when a process is preempted. Reducing preemption cause the issue to be fare less likely to occur.=20 When it fails(in the load case), I've traced it down to do_fp_load. It fai= ls when it takes the false branch while it works when taking the true branch (= see https://elixir.bootlin.com/linux/v5.4.110/source/arch/powerpc/lib/sstep.c#L= 492). The issue was originally seen on a preempt-rt kernel, but it can be reprodu= ced on a regular kernel compiled for low latency desktop as well. The issue can be reproduced with the attached program which just performs an unaligned FP load. Eventually it will produce a zero and exit.=20=20 Example output: 11326b98 22453191 3357f78a 446abd71 557d70b6 11326b98 22453191 3357f78a 446abd71 557d70b6 11326b98 22453191 3357f78a 00000000 float-bug: float-bug.c:14: main: Assertion `b[0] !=3D 00' failed. This has been compiled with gcc 9.3.0. --=20 You may reply to this email to add a comment. 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