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=-0.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 4CE19C46460 for ; Tue, 7 May 2019 12:54:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 25A32214C6 for ; Tue, 7 May 2019 12:54:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726678AbfEGMyX (ORCPT ); Tue, 7 May 2019 08:54:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:37388 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726000AbfEGMyX (ORCPT ); Tue, 7 May 2019 08:54:23 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 9914C20578; Tue, 7 May 2019 12:54:19 +0000 (UTC) Date: Tue, 7 May 2019 08:54:17 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: Linus Torvalds , Andy Lutomirski , Linux List Kernel Mailing , Ingo Molnar , Andrew Morton , Andy Lutomirski , Nicolai Stange , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , the arch/x86 maintainers , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Shuah Khan , Konrad Rzeszutek Wilk , Tim Chen , Sebastian Andrzej Siewior , Mimi Zohar , Juergen Gross , Nick Desaulniers , Nayna Jain , Masahiro Yamada , Joerg Roedel , "open list:KERNEL SELFTEST FRAMEWORK" , stable , Masami Hiramatsu Subject: Re: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions Message-ID: <20190507085417.381d96d0@gandalf.local.home> In-Reply-To: <20190507124131.GO2623@hirez.programming.kicks-ass.net> References: <20190502193129.664c5b2e@gandalf.local.home> <20190502195052.0af473cf@gandalf.local.home> <20190503092959.GB2623@hirez.programming.kicks-ass.net> <20190503092247.20cc1ff0@gandalf.local.home> <2045370D-38D8-406C-9E94-C1D483E232C9@amacapital.net> <20190506081951.GJ2606@hirez.programming.kicks-ass.net> <20190507085753.GO2606@hirez.programming.kicks-ass.net> <20190507092731.GH2650@hirez.programming.kicks-ass.net> <20190507082716.73cd5a01@gandalf.local.home> <20190507124131.GO2623@hirez.programming.kicks-ass.net> 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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 7 May 2019 14:41:31 +0200 Peter Zijlstra wrote: > > Kprobes sets the FTRACE_OPS_FL_IPMODIFY flag, thus > > they can never be put at the same location that is being live patched. > > OK, so do we want to allow kprobes that also modify regs->sp ? Because > then we need to change these trampolines a bit. > > I'd prefer not to allow kprobes this. I believe no kprobe changes sp, because it would have had the same issues we are trying to solve now. And even though we are changing things to allow it, it's not a regression to keep kprobes from doing it. -- Steve