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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 43753C43610 for ; Thu, 29 Nov 2018 18:47:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 165A72146D for ; Thu, 29 Nov 2018 18:47:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 165A72146D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726600AbeK3Fxu (ORCPT ); Fri, 30 Nov 2018 00:53:50 -0500 Received: from mail.kernel.org ([198.145.29.99]:50038 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726393AbeK3Fxu (ORCPT ); Fri, 30 Nov 2018 00:53:50 -0500 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (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 285A920868; Thu, 29 Nov 2018 18:47:27 +0000 (UTC) Date: Thu, 29 Nov 2018 13:47:25 -0500 From: Steven Rostedt To: Linus Torvalds Cc: Andy Lutomirski , Josh Poimboeuf , Peter Zijlstra , Andrew Lutomirski , "the arch/x86 maintainers" , Linux List Kernel Mailing , Ard Biesheuvel , Ingo Molnar , Thomas Gleixner , mhiramat@kernel.org, jbaron@akamai.com, Jiri Kosina , David.Laight@aculab.com, bp@alien8.de, julia@ni.com, jeyu@kernel.org, Peter Anvin Subject: Re: [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64 Message-ID: <20181129134725.6d86ade6@gandalf.local.home> In-Reply-To: References: <20181126160217.GR2113@hirez.programming.kicks-ass.net> <20181126200801.GW2113@hirez.programming.kicks-ass.net> <20181126212628.4apztfazichxnt7r@treble> <20181127084330.GX2113@hirez.programming.kicks-ass.net> <20181129094210.GC2131@hirez.programming.kicks-ass.net> <20181129143853.GO2131@hirez.programming.kicks-ass.net> <20181129163342.tp5wlfcyiazwwyoh@treble> <0A629D30-ADCF-4159-9443-E5727146F65F@amacapital.net> <20181129121307.12393c57@gandalf.local.home> <20181129124404.2fe55dd0@gandalf.local.home> <20181129125857.75c55b96@gandalf.local.home> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 29 Nov 2018 10:23:44 -0800 Linus Torvalds wrote: > On Thu, Nov 29, 2018 at 9:59 AM Steven Rostedt wrote: > > > > Do you realize that the cmpxchg used by the first attempts of the > > dynamic modification of code by ftrace was the source of the e1000e > > NVRAM corruption bug. > > If you have a static call in IO memory, you have bigger problems than that. > > What's your point? Just that cmpxchg on dynamic modified code brings back bad memories ;-) > > Again - I will point out that the things you guys have tried to come > up with have been *WORSE*. Much worse. Note, we do have a bit of control at what is getting called. The patch set requires that the callers are wrapped in macros. We should not allow just any random callers (like from asm). This isn't about modifying any function call. This is for a specific subset, that we can impose rules on. -- Steve