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 415DBC47247 for ; Tue, 5 May 2020 14:22:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A52F20675 for ; Tue, 5 May 2020 14:22:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730086AbgEEOW4 (ORCPT ); Tue, 5 May 2020 10:22:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48628 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1729495AbgEEOOK (ORCPT ); Tue, 5 May 2020 10:14:10 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A02AC061A10 for ; Tue, 5 May 2020 07:14:10 -0700 (PDT) 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 1jVyKW-0000ko-QA; Tue, 05 May 2020 16:13:52 +0200 Received: from nanos.tec.linutronix.de (localhost [IPv6:::1]) by nanos.tec.linutronix.de (Postfix) with ESMTP id 54A49FFC8D; Tue, 5 May 2020 16:13:52 +0200 (CEST) Message-Id: <20200505134101.139720912@linutronix.de> User-Agent: quilt/0.65 Date: Tue, 05 May 2020 15:16:33 +0200 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, "Paul E. McKenney" , Andy Lutomirski , Alexandre Chartre , Frederic Weisbecker , Paolo Bonzini , Sean Christopherson , Masami Hiramatsu , Petr Mladek , Steven Rostedt , Joel Fernandes , Boris Ostrovsky , Juergen Gross , Brian Gerst , Mathieu Desnoyers , Josh Poimboeuf , Will Deacon , "Peter Zijlstra (Intel)" Subject: [patch V4 part 1 31/36] printk: Disallow instrumenting print_nmi_enter() References: <20200505131602.633487962@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-transfer-encoding: 8-bit 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 From: Peter Zijlstra It happens early in nmi_enter(), no tracing, probing or other funnies allowed. Specifically as nmi_enter() will be used in do_debug(), which would cause recursive exceptions when kprobed. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner --- kernel/printk/printk_safe.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/kernel/printk/printk_safe.c +++ b/kernel/printk/printk_safe.c @@ -10,6 +10,7 @@ #include #include #include +#include #include "internal.h" @@ -293,12 +294,12 @@ static __printf(1, 0) int vprintk_nmi(co return printk_safe_log_store(s, fmt, args); } -void notrace printk_nmi_enter(void) +void noinstr printk_nmi_enter(void) { this_cpu_add(printk_context, PRINTK_NMI_CONTEXT_OFFSET); } -void notrace printk_nmi_exit(void) +void noinstr printk_nmi_exit(void) { this_cpu_sub(printk_context, PRINTK_NMI_CONTEXT_OFFSET); }