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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 E515DC433E0 for ; Sat, 27 Jun 2020 15:52:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AC5D121852 for ; Sat, 27 Jun 2020 15:52:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="BWOD2zVO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726057AbgF0Pwy (ORCPT ); Sat, 27 Jun 2020 11:52:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50712 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725932AbgF0Pwx (ORCPT ); Sat, 27 Jun 2020 11:52:53 -0400 Received: from mail-pj1-x1044.google.com (mail-pj1-x1044.google.com [IPv6:2607:f8b0:4864:20::1044]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90608C03E979 for ; Sat, 27 Jun 2020 08:52:53 -0700 (PDT) Received: by mail-pj1-x1044.google.com with SMTP id ci15so38269pjb.5 for ; Sat, 27 Jun 2020 08:52:53 -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=41PjtVw2FCnymQIWQmtqJCNWG/zIBsJ1p+vOmqPkCKE=; b=BWOD2zVOkpWNo2bPFp4ryz2GzTvlrG4eRcB7J1dRZGF2dC02SxWF6s4ngC2sUr5+Bb eDY2hiyrwzKyw5MPZkEq3pceBPMsMcWggsPLBtAFkb3BeqEQctFko234Pn4GYrqlFPY2 CUyBk7DmCZTz9+V2L2y1dJEjvvVQ3YRUIPMkE= 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=41PjtVw2FCnymQIWQmtqJCNWG/zIBsJ1p+vOmqPkCKE=; b=XLgcakoicnL3pPZasoUqXeYpB98hInnPtiB9IFPqvG6DboFJdSpRbpINzyfPHH0s9t xdg8BZc16yi5j0CFSMP4kv+4vEbnaw0zbbfQ2UiDzfmaUh6o2PXha2e48VGDteWp68ai PL9jY6QiwdEoKL66olB5sUKnfa1aSMovM5gkEbkRLZtbxJToIC39qdPMn0KadmWZKO+w K9/QJr3EqpC0rYd+gNugF4cJJsS3H80AiLQwV/SPBUvgUNvY8AstbqsnOdfNVn4PrMsR jKPfmQIRGXFlQmrCvj8Y8bz8OAaFXgCVZC+gO1lQIrz1GVGzROu5BkgdpRTW0LrbDxIy L5zQ== X-Gm-Message-State: AOAM532JEAeSdTHofdr+LJmJZncemmvy1MtWLDxACM9NOip37FmIWAjQ eZ7PSuaeBed+rxdS9Uyd1eKx0w== X-Google-Smtp-Source: ABdhPJwq0luAdpdlmLTPEl4oe8Od9vPb+TjMSBktwbCClEDhgr3jX3UYqoZ/0w+XuhMn1QXco7RLsA== X-Received: by 2002:a17:90a:8545:: with SMTP id a5mr9009522pjw.35.1593273173171; Sat, 27 Jun 2020 08:52:53 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id b13sm7419617pjl.7.2020.06.27.08.52.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 27 Jun 2020 08:52:52 -0700 (PDT) Date: Sat, 27 Jun 2020 08:52:50 -0700 From: Kees Cook To: Michael Ellerman Cc: Shuah Khan , Naresh Kamboju , Petr Mladek , Joe Lawrence , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] selftests/lkdtm: Use "comm" instead of "diff" for dmesg Message-ID: <202006270849.7190A26@keescook> References: <202006261358.3E8AA623A9@keescook> <87k0zsbubg.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87k0zsbubg.fsf@mpe.ellerman.id.au> Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Sat, Jun 27, 2020 at 09:51:31PM +1000, Michael Ellerman wrote: > Kees Cook writes: > > Instead of full GNU diff (which smaller boot environments may not have), > > use "comm" which is more available. > > Although using "comm" requires CONFIG_PRINTK_TIME=y doesn't it? No, it doesn't seem to. "comm" doesn't carry about the line prefixes. AIUI, the only reason for a mention of "sort" is because of how "comm" does its line pairing. i.e. as soon as it goes out of sync, it starts accounting for the disjunction between files. But that's exactly what we want it doing, and the prefix doesn't matter. -- Kees Cook