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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 E7EE1C433E0 for ; Fri, 5 Jun 2020 21:26:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1ED32065C for ; Fri, 5 Jun 2020 21:26:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="g6yt5mow" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728443AbgFEV0k (ORCPT ); Fri, 5 Jun 2020 17:26:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59754 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726664AbgFEV0j (ORCPT ); Fri, 5 Jun 2020 17:26:39 -0400 Received: from mail-pl1-x643.google.com (mail-pl1-x643.google.com [IPv6:2607:f8b0:4864:20::643]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F37D5C08C5C2 for ; Fri, 5 Jun 2020 14:26:38 -0700 (PDT) Received: by mail-pl1-x643.google.com with SMTP id n2so4182444pld.13 for ; Fri, 05 Jun 2020 14:26:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=VeRb96m3xb6MVLzkZ/9bi8Q4G4C90sZuPgPUM9psnlg=; b=g6yt5mowRomsCxHiTj+rCKQTPIaAlRT3+6FakMUq17fUAUSWHCWdqhopSjjJkFIDA5 dfGjWJilOucVdz4mqVU7cY+rQEki0+UNYc/UVTAG3xfptu0L1WsBJMzErpMNcjTeoyGy ZG4IzyxBW7zpLK2FoAUiqwNhUmpEqqjumjDtE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=VeRb96m3xb6MVLzkZ/9bi8Q4G4C90sZuPgPUM9psnlg=; b=YmnmKSswxi27sJHf42vQuwL0OHJyA9n1GnUPnMzaccE6yEezcxBXp3ercWGtrDcKXI beymdZsm1j7tO8OBJiy4dbfdLFYLW037bqW/zoxoDQG6Lw+XB0/3dMYELs1X6kvSi7/m HPnOq0uuCp/k22sFjvu+Yjq9PatQPpj+2riWxNc3wnKbLls+u+Hh4C0y43M95tupvG+F PFM46YXIcHY+n5avshYDR1/1gO9bMk7wOM4wHHIWVSPMfGQoO+u2mmd8Eu0VbZtM87xR 35OvBeR6Nq15l/oSC5QxPw2WNBPGxg8HoBIEx0b8HqVyNK1A/TMSR6PFfuTqUd8auEcm 9UIA== X-Gm-Message-State: AOAM530x/0eZkcHMqaljUFBnVPoz39XrwLwr/lyK8/RTSuHIOZnhkBME iuC0dNKmDGLpFe0GnEuJPVn2bw== X-Google-Smtp-Source: ABdhPJw0V3kMeUm0jvO13avWqD+DqRkUeahiiWaS1x3LL2XqbIN2sZ84eMR0ycj8tzYPERJRxmEJ8g== X-Received: by 2002:a17:90a:ac0f:: with SMTP id o15mr5167862pjq.105.1591392398559; Fri, 05 Jun 2020 14:26:38 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id o18sm528652pfu.138.2020.06.05.14.26.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Jun 2020 14:26:37 -0700 (PDT) Date: Fri, 5 Jun 2020 14:26:36 -0700 From: Kees Cook To: Pavel Tatashin Cc: jmorris@namei.org, sashal@kernel.org, pmladek@suse.com, ebiederm@xmission.com, anton@enomsg.org, ccross@android.com, tony.luck@intel.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] kexec: dump kmessage before machine_kexec Message-ID: <202006051426.4F06C696@keescook> References: <20200605194642.62278-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200605194642.62278-1-pasha.tatashin@soleen.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 05, 2020 at 03:46:42PM -0400, Pavel Tatashin wrote: > kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before > machine_restart(), machine_halt(), machine_power_off(), the only one that > is missing is machine_kexec(). > > The dmesg output that it contains can be used to study the shutdown > performance of both kernel and systemd during kexec reboot. > > Here is example of dmesg data collected after kexec: > > root@dplat-cp22:~# cat /sys/fs/pstore/dmesg-ramoops-0 | tail > ... > <6>[ 70.914592] psci: CPU3 killed (polled 0 ms) > <5>[ 70.915705] CPU4: shutdown > <6>[ 70.916643] psci: CPU4 killed (polled 4 ms) > <5>[ 70.917715] CPU5: shutdown > <6>[ 70.918725] psci: CPU5 killed (polled 0 ms) > <5>[ 70.919704] CPU6: shutdown > <6>[ 70.920726] psci: CPU6 killed (polled 4 ms) > <5>[ 70.921642] CPU7: shutdown > <6>[ 70.922650] psci: CPU7 killed (polled 0 ms) > > Signed-off-by: Pavel Tatashin Reviewed-by: Kees Cook -- Kees Cook