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 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 3E611C04A6B for ; Tue, 7 May 2019 02:58:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1786120856 for ; Tue, 7 May 2019 02:58:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726862AbfEGC6Y (ORCPT ); Mon, 6 May 2019 22:58:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:47852 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726346AbfEGC6Y (ORCPT ); Mon, 6 May 2019 22:58:24 -0400 Received: from oasis.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 0FCB920835; Tue, 7 May 2019 02:58:20 +0000 (UTC) Date: Mon, 6 May 2019 22:58:19 -0400 From: Steven Rostedt To: Linus Torvalds Cc: Peter Zijlstra , 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: <20190506225819.11756974@oasis.local.home> In-Reply-To: References: <20190502181811.GY2623@hirez.programming.kicks-ass.net> <20190506081951.GJ2606@hirez.programming.kicks-ass.net> <20190506095631.6f71ad7c@gandalf.local.home> <20190506130643.62c35eeb@gandalf.local.home> <20190506145745.17c59596@gandalf.local.home> <20190506162915.380993f9@gandalf.local.home> <20190506174511.2f8b696b@gandalf.local.home> <20190506210416.2489a659@oasis.local.home> <20190506215353.14a8ef78@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 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, 6 May 2019 19:22:06 -0700 Linus Torvalds wrote: > Notice? We'd not even have to look up any values. We'd literally just > do something like > > int offset = locked_atomic_read(ip+1); > return int3_emulate_call(ip, ip+5+offset); > > and it would be *atomic* with respect to whatever other user that > updates the instruction, as long as they update the offset with a > "xchg" instruction. Honestly, I'm not really sure what you are trying to do here. Are you talking about making the update to the code in the int3 handler? And then just returning back to the regs->ip and executing the new call (not really emulating). -- Steve