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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 3A190C3F2CD for ; Mon, 23 Mar 2020 16:04:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 16C1D20637 for ; Mon, 23 Mar 2020 16:04:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727439AbgCWQEC (ORCPT ); Mon, 23 Mar 2020 12:04:02 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:41889 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727239AbgCWQEC (ORCPT ); Mon, 23 Mar 2020 12:04:02 -0400 Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jGPXx-0001ch-LY; Mon, 23 Mar 2020 17:03:25 +0100 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 056D11040AA; Mon, 23 Mar 2020 17:03:24 +0100 (CET) From: Thomas Gleixner To: Masami Hiramatsu Cc: LKML , x86@kernel.org, Paul McKenney , Josh Poimboeuf , "Joel Fernandes \(Google\)" , "Steven Rostedt \(VMware\)" , Masami Hiramatsu , Alexei Starovoitov , Frederic Weisbecker , Mathieu Desnoyers , Brian Gerst , Juergen Gross , Alexandre Chartre , Peter Zijlstra , Tom Lendacky , Paolo Bonzini , kvm@vger.kernel.org Subject: Re: [patch V3 04/23] kprobes: Prevent probes in .noinstr.text section In-Reply-To: <20200323230025.a24f949a2143dbd5f208f00c@kernel.org> References: <20200320175956.033706968@linutronix.de> <20200320180032.799569116@linutronix.de> <20200323230025.a24f949a2143dbd5f208f00c@kernel.org> Date: Mon, 23 Mar 2020 17:03:24 +0100 Message-ID: <87mu87oy7n.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Masami, Masami Hiramatsu writes: > On Fri, 20 Mar 2020 19:00:00 +0100 > Thomas Gleixner wrote: > >> Instrumentation is forbidden in the .noinstr.text section. Make kprobes >> respect this. >> >> This lacks support for .noinstr.text sections in modules, which is required >> to handle VMX and SVM. >> > > Would you have any plan to list or mark the noinstr symbols on > some debugfs interface? I need a blacklist of those symbols so that > user (and perf-probe) can check which function can not be probed. > > It is just calling kprobe_add_area_blacklist() like below. > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 2625c241ac00..4835b644bd2b 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -2212,6 +2212,10 @@ static int __init populate_kprobe_blacklist(unsigned long *start, > ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start, > (unsigned long)__kprobes_text_end); > > + /* Symbols in noinstr section are blacklisted */ > + ret = kprobe_add_area_blacklist((unsigned long)__noinstr_text_start, > + (unsigned long)__noinstr_text_end); > + > return ret ? : arch_populate_kprobe_blacklist(); > } So that extra function is not required when adding that, right? >> +/* Functions in .noinstr.text must not be probed */ >> +static bool within_noinstr_text(unsigned long addr) >> +{ >> + /* FIXME: Handle module .noinstr.text */ >> + return addr >= (unsigned long)__noinstr_text_start && >> + addr < (unsigned long)__noinstr_text_end; >> +} >> + >> bool within_kprobe_blacklist(unsigned long addr) >> { >> char symname[KSYM_NAME_LEN], *p; >> >> + if (within_noinstr_text(addr)) >> + return true; >> + >> if (__within_kprobe_blacklist(addr)) >> return true;