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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 1187FC433F5 for ; Mon, 14 Feb 2022 11:35:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To: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-Owner; bh=5DBLHocZXOrYZ3nwGtJYsWAAlgD0dNrbUWUTwagmyjQ=; b=vi916Yb6+JGehL o1Em3ZiKuNkpj8VRZi5+8xJLH6Et5cBOW6k7Hsyobw+8OM5itigxXWr0hUZzCadV6DWVTVFKOSt3s lvShjC62XgJYAhwqRs8+Qtd2lW2+kOAX2O7R0XEHPAwczAd3tSJVtDNzP3VN06ODsRqlNIBSFNbVM CNPNmwz2rZ/CGrEPPRaCpN23wBGgha66bOTol7by2XY+wDahVCF3lyFG14YKSWUFBKNrrMNgV0sk2 4CbOUT+zu4D+uu75jYjAmWystUIi6DMTUGZuSw13GeRtFCljDoNQ7Izmaua5QGVkkZKDZHVc28gcG ijFtAPPvyEtAh+A/o7fQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nJZcB-00Eqdu-PM; Mon, 14 Feb 2022 11:33:56 +0000 Received: from pandora.armlinux.org.uk ([2001:4d48:ad52:32c8:5054:ff:fe00:142]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nJYMq-00ERVw-Jk for linux-arm-kernel@lists.infradead.org; Mon, 14 Feb 2022 10:14:02 +0000 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-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding: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=3MsnB0/FbfNbekz7W6OC3rgHiQiWzuJWuoC9EJ7EWog=; b=FYZLrS4ZlYUVF9of4NT3JTUh51 6qJ9YwaBmRqx5vk4jMCrtNLs6RS1NKlYEkkQphURePlomiLBZ2zIDpZzwUkP+BOiGcHmrgu/g/JaK Q1xUpx9Xm0CHFTCD8cDGOGqPZEVlIuXtAPle8MnbtQC4Zy3xqv3yyTJ20BJA+jObdS3goulR0wDrk vjZajvSG3f3xpYNEa4Xvm3JjNNYWGNJOJfmlnnqwXr3bD/kqUbr/fao7Lgz10+xT/O+LneqK5LSqX 2Dl6Fx4VKO3Kc6b19UL+ZOTQQZJpwSac2ILdUHhxDV+Z9ddGlBZcnUi3b7JKmwXi91xTiTiELJh5j K5rNszPg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:57244) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1nJYMa-0001IP-1z; Mon, 14 Feb 2022 10:13:44 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1nJYMZ-0006S9-Fi; Mon, 14 Feb 2022 10:13:43 +0000 Date: Mon, 14 Feb 2022 10:13:43 +0000 From: "Russell King (Oracle)" To: Johannes Stezenbach Cc: linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] arm kgdb: fix breakpoint for thumb2 Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220214_021400_709104_A6A2149D X-CRM114-Status: UNSURE ( 9.75 ) X-CRM114-Notice: Please train this message. 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="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Feb 14, 2022 at 10:59:49AM +0100, Johannes Stezenbach wrote: > Entering kdb via SysRq-G with CONFIG_THUMB2_KERNEL=y > on Cortex-A7 in Qemu results in an Ooops, and it is > not possible to continue because of "Catastrophic error detected". > The root cause is using an arm breakpoint instruction in > thumb code. This sounds like a bug in qemu. 0xe7ffdeXX is two 16-bit instructions: 0: e7ff b.n 2 <.text+0x2> 2: def1 udf #241 ; 0xf1 0xe7ff is a branch to the UDF instruction. 0xdeXX is a UDF (Permanently undefined) instruction which should raise a undefined instruction trap. As per the Arm ARM on UDF: "Permanently Undefined generates an Undefined Instruction exception." The encoding is also a 32-bit UDF instruction: 0: e7ffdef1 udf #64993 ; 0xfde1 which is exactly why these opcodes were chosen - so we can instrument both ARM and Thumb code without caring which it is. Qemu needs fixing if it complains about this. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel