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, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 5562CC3F2D2 for ; Sun, 8 Mar 2020 23:24:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2C259208C3 for ; Sun, 8 Mar 2020 23:24:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726750AbgCHXX4 (ORCPT ); Sun, 8 Mar 2020 19:23:56 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:57227 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726640AbgCHXXw (ORCPT ); Sun, 8 Mar 2020 19:23:52 -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 1jB5Ga-00033Q-UE; Mon, 09 Mar 2020 00:23:29 +0100 Received: from nanos.tec.linutronix.de (localhost [IPv6:::1]) by nanos.tec.linutronix.de (Postfix) with ESMTP id 63673104097; Mon, 9 Mar 2020 00:23:28 +0100 (CET) Message-Id: <20200308222609.125574449@linutronix.de> User-Agent: quilt/0.65 Date: Sun, 08 Mar 2020 23:24:01 +0100 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Steven Rostedt , Brian Gerst , Juergen Gross , Frederic Weisbecker , Alexandre Chartre Subject: [patch part-II V2 02/13] x86/entry: Mark enter_from_user_mode() notrace and NOKPROBE References: <20200308222359.370649591@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 Both the callers in the low level ASM code and __context_tracking_exit() which is invoked from enter_from_user_mode() via user_exit_irqoff() are marked NOKPROBE. Allowing enter_from_user_mode() to be probed is inconsistent at best. Aside of that while function tracing per se is safe the function trace entry/exit points can be used via BPF as well which is not safe to use before context tracking has reached CONTEXT_KERNEL and adjusted RCU. Mark it notrace and NOKROBE. Signed-off-by: Thomas Gleixner --- arch/x86/entry/common.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -40,11 +40,12 @@ #ifdef CONFIG_CONTEXT_TRACKING /* Called on entry from user mode with IRQs off. */ -__visible inline void enter_from_user_mode(void) +__visible inline notrace void enter_from_user_mode(void) { CT_WARN_ON(ct_state() != CONTEXT_USER); user_exit_irqoff(); } +NOKPROBE_SYMBOL(enter_from_user_mode); #else static inline void enter_from_user_mode(void) {} #endif