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 2AE9FC43219 for ; Mon, 29 Apr 2019 18:52:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 04F6821655 for ; Mon, 29 Apr 2019 18:52:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729263AbfD2Swy (ORCPT ); Mon, 29 Apr 2019 14:52:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:50454 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729027AbfD2Swy (ORCPT ); Mon, 29 Apr 2019 14:52:54 -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 996AA2075E; Mon, 29 Apr 2019 18:52:51 +0000 (UTC) Date: Mon, 29 Apr 2019 14:52:50 -0400 From: Steven Rostedt To: Linus Torvalds Cc: Peter Zijlstra , 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 , Andy Lutomirski , Joerg Roedel , Linux List Kernel Mailing , live-patching@vger.kernel.org, "open list:KERNEL SELFTEST FRAMEWORK" Subject: Re: [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation Message-ID: <20190429145250.1a5da6ed@gandalf.local.home> In-Reply-To: References: <20190427100639.15074-1-nstange@suse.de> <20190427100639.15074-4-nstange@suse.de> <20190427102657.GF2623@hirez.programming.kicks-ass.net> <20190428133826.3e142cfd@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: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 29 Apr 2019 11:06:58 -0700 Linus Torvalds wrote: > +void replace_call(void *addr, const void *opcode, size_t len, void *target) > +{ > + bp_int3_call_target = target; > + bp_int3_call_return = addr + len; > + bp_int3_handler_irqoff = emulate_call_irqoff; > + text_poke_bp(addr, opcode, len, emulate_call_irqon); > +} Note, the function tracer does not use text poke. It does it in batch mode. It can update over 40,000 calls in one go: add int3 breakpoint to all 40,000 call sites. sync() change the last four bytes of each of those call sites sync() remove int3 from the 40,000 call site with new call. It's a bit more intrusive than the static call updates we were discussing before. -- Steve