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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 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 E7D68C433E1 for ; Fri, 24 Jul 2020 17:48:32 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 42B43206F6 for ; Fri, 24 Jul 2020 17:48:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 42B43206F6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-19441-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 5557 invoked by uid 550); 24 Jul 2020 17:48:26 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 5537 invoked from network); 24 Jul 2020 17:48:25 -0000 Date: Fri, 24 Jul 2020 13:48:11 -0400 From: Steven Rostedt To: Oscar Carter Cc: Ingo Molnar , Kees Cook , linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, Jann Horn Subject: Re: [PATCH v2 2/2] kernel/trace: Remove function callback casts Message-ID: <20200724134811.01704cbf@oasis.local.home> In-Reply-To: <20200724134020.3160dc7c@oasis.local.home> References: <20200719155033.24201-1-oscar.carter@gmx.com> <20200719155033.24201-3-oscar.carter@gmx.com> <20200721140545.445f0258@oasis.local.home> <20200724161921.GA3123@ubuntu> <20200724123528.36ea9c9e@oasis.local.home> <20200724171418.GB3123@ubuntu> <20200724133656.76c75629@oasis.local.home> <20200724134020.3160dc7c@oasis.local.home> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 24 Jul 2020 13:40:20 -0400 Steven Rostedt wrote: > On Fri, 24 Jul 2020 13:36:56 -0400 > Steven Rostedt wrote: > > > Which BTW, is supported by the following architectures: > > x86 Ah, you can lose support on x86 if you don't enable DYNAMIC_FTRACE, which is stupid to do. I only enabled disabling of DYNAMIC_FTRACE on x86 to test it, as not all architectures have it, and I currently only test on x86. Without DYNAMIC_FTRACE enabled, you *always* call into the ftrace infrastructure for *every* function. This adds something like 15 to 20% overhead to the kernel. Did I say it was stupid to do so? If you are going through all this work because some randconfig causes this warning because it enables CONFIG_FUNCTION_TRACER but without DYNAMIC_FTRACE enabled, then I strongly suggest you start spending your time elsewhere, because it will be a big NAK on my part to add all this intrusive code for a config used only for debugging the non DYNAMIC_FTRACE case. -- Steve