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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 E8A4CC433E0 for ; Mon, 25 May 2020 08:36:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B7D342070A for ; Mon, 25 May 2020 08:36:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="VNwvzhjB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731363AbgEYIgo (ORCPT ); Mon, 25 May 2020 04:36:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47336 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726222AbgEYIgn (ORCPT ); Mon, 25 May 2020 04:36:43 -0400 Received: from merlin.infradead.org (unknown [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7760DC061A0E for ; Mon, 25 May 2020 01:36:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Type:MIME-Version:Message-ID: Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:In-Reply-To:References; bh=RTpKspGxVJJJi40+OUi0+PfMkju25wl6tiprFTvOugk=; b=VNwvzhjBBZXZ2K2tL7OAJ5w6oz ax0hT+LSYqqSAmwOkTkkfqSESGiRuf8XMC9qd7lSg2frS2RrrEW2GiSLeOCfaiFhpPIfFngr1medj oYaxzNhOJd0KIRhVPNdWKBSBdiInxW/QbkEsSwgmDIO3ahbfcUuVj/YbxwhBFzFGv7L8TkgOLbFgK inS01PxZV0sIzL5o1bdLN8zWkVBChNR+XRwkDI1Mra6jHEKGiSuzgxjY4EXaEhWTT/HvEalOCKfq0 UeliyZYl2fMcLHPoMt1bZvilzCGaYzcoXg7t+/9s6DhrNvEApFN/gIb4d7ZSi9FY2sjd0RRTHokLL rkeDP5qg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jd8ad-0001w8-Kw; Mon, 25 May 2020 08:36:07 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 277353011E6; Mon, 25 May 2020 10:36:05 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0D13721462C5D; Mon, 25 May 2020 10:36:05 +0200 (CEST) Date: Mon, 25 May 2020 10:36:05 +0200 From: Peter Zijlstra To: daniel.thompson@linaro.org, x86@kernel.org Cc: sumit.garg@linaro.org, jason.wessel@windriver.com, dianders@chromium.org, kgdb-bugreport@lists.sourceforge.net, linux-kernel@vger.kernel.org, pmladek@suse.com, sergey.senozhatsky@gmail.com, will@kernel.org Subject: x86/entry vs kgdb Message-ID: <20200525083605.GB317569@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! Since you seem to care about kgdb, I figured you might want to fix this before I mark it broken on x86 (we've been considering doing that for a while). AFAICT the whole debugreg usage of kgdb-x86_64 is completely hosed; it doesn't respsect the normal exclusion zones as per arch_build_bp_info(). That is, breakpoints must never be in: - in the cpu_entry_area - in .entry.text - in .noinstr.text - in anything else marked NOKPROBE by not respecting these constraints it is trivial to completely and utterly hose the machine. The entry rework that is current underway will explicitly not deal with #DB triggering in any of those places.