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=-9.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,NICE_REPLY_A,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 D995EC4363A for ; Tue, 27 Oct 2020 10:43:51 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 64D7220878 for ; Tue, 27 Oct 2020 10:43:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="AsosFS+b"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="wBCMVkoZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 64D7220878 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Mime-Version:References:In-Reply-To:Message-Id: Subject: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=ayS7maf4//7hwJ+Wpm/RgVYjrr7jJkU0FHM8n7aD0/I=; b=AsosFS+bHb9Ly0Y45tOB3JHzL ML5I8eW97PO/chVOYFGE4h1EvVScKeGUl+P2KATzfm7AKigyVnwPlYKvhW5bdc0X+TmIlYTrRXtfD n1ZFztaWTrgrZEYoY2ZRSs2ptpvCoAvnJmcooYDnXFbwO5q0FiW0Y0xstIPzQ4VdYREiKSjk51O7I ZZExwNotM6tyRcdoL88+xpKOfMmDyNiLsI+a7LjrpYwtae0kd1VM+/qrxI4yUE5jIwXiS94mSZi79 1y9OsazCA5FycE/B6vzpXF2aU+CgX1a/q19DvQ+6DZK5Wee4EsJNQcd4uWnMYr/ZXISsf1jlG6dTy 1MoBLInBA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kXMRd-0001o2-M8; Tue, 27 Oct 2020 10:43:13 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kXMRS-0001ld-4T for linux-arm-kernel@lists.infradead.org; Tue, 27 Oct 2020 10:43:03 +0000 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DFB3820878; Tue, 27 Oct 2020 10:42:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603795381; bh=szjxaDARNYj5IQE5QirIs4AR9Qzi3ZQko4Mew1E/AFU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=wBCMVkoZpqgQ7EKiiZbswETEAlNP9Qai9TMbZIRkvTFi5ujZ0xDJc7Dm9DTmTRsvh shXBt6eYv8XLKJ/lvJXqg4gPMWf7Bscb6HZMshaAvp0r1kfw8fxI5ayrGF14sDXLEz x5JeNQROOpB0sq9qoHoQ+GfNkjK/+PL9EBBq45Lg= Date: Tue, 27 Oct 2020 19:42:58 +0900 From: Masami Hiramatsu To: Masami Hiramatsu Subject: Re: [PATCH] arm64: Fix early single-stepping Message-Id: <20201027194258.43b157ac0bbccd918fc8756a@kernel.org> In-Reply-To: <20201027191318.aba935f7ccf00af9acd89388@kernel.org> References: <20201026172907.1468294-1-jean-philippe@linaro.org> <20201027191318.aba935f7ccf00af9acd89388@kernel.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201027_064302_354494_64BB7140 X-CRM114-Status: GOOD ( 21.05 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jean-Philippe Brucker , will@kernel.org, dianders@chromium.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com 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 Tue, 27 Oct 2020 19:13:18 +0900 Masami Hiramatsu wrote: > On Mon, 26 Oct 2020 18:29:09 +0100 > Jean-Philippe Brucker wrote: > > > To use debug features such as single-step, the OS lock must be unlocked > > in the debug registers. Currently this is done in postcore_initcall > > which is now too late. > > > > Commit 36dadef23fcc ("kprobes: Init kprobes in early_initcall") enabled > > using kprobes from early_initcall, when OS lock is still locked. So when > > kprobe attempts to single-step a patched instruction, instead of > > trapping, execution continues until it throws an undef exception: > > > > [ 0.064233] Kprobe smoke test: started > > [ 0.151133] ------------[ cut here ]------------ > > [ 0.151458] kernel BUG at arch/arm64/kernel/traps.c:406! > > [ 0.151812] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP > > ... > > [ 0.162689] Call trace: > > [ 0.163014] do_undefinstr+0x1d4/0x1f4 > > [ 0.163336] el1_sync_handler+0xbc/0x140 > > [ 0.163839] el1_sync+0x80/0x100 > > [ 0.164154] 0xffffffc01001d004 > > [ 0.164527] init_kprobes+0x13c/0x154 > > [ 0.164968] do_one_initcall+0x54/0x2e0 > > [ 0.165322] kernel_init_freeable+0xf4/0x258 > > [ 0.165783] kernel_init+0x20/0x12c > > [ 0.166117] ret_from_fork+0x10/0x30 > > [ 0.166595] Code: 97ffff53 a9425bf5 17ffff9b f9001bf7 (d4210000) > > [ 0.167084] ---[ end trace 36778fdf576e9a79 ]--- > > > > To fix this, unlock the OS lock as early as possible. Do it in > > traps_init() for CPU0, since KGDB wants to use single-step from that > > point on according to commit b322c65f8ca3 ("arm64: Call > > debug_traps_init() from trap_init() to help early kgdb"). > > For secondary CPUs, setup the CPU hotplug handler at early_initcall. > > > > Fixes: 36dadef23fcc ("kprobes: Init kprobes in early_initcall") > > Signed-off-by: Jean-Philippe Brucker > > Hi Jean, > > How have you confirmed this fixes the issue? > On my environment, this doesn't fix the issue. Oops, it was my mistake. I missed to boot up with Xen. (so I find another bug...) Anyway this works for me too. Reviewed-by: Masami Hiramatsu Tested-by: Masami Hiramatsu Thank you! -- Masami Hiramatsu _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel