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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 E3A7BC47247 for ; Tue, 5 May 2020 14:14:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CEC2C20836 for ; Tue, 5 May 2020 14:14:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729641AbgEEOOn (ORCPT ); Tue, 5 May 2020 10:14:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1729630AbgEEOOl (ORCPT ); Tue, 5 May 2020 10:14:41 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFC01C061A10 for ; Tue, 5 May 2020 07:14:40 -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 1jVyL1-00011q-GB; Tue, 05 May 2020 16:14:23 +0200 Received: from nanos.tec.linutronix.de (localhost [IPv6:::1]) by nanos.tec.linutronix.de (Postfix) with ESMTP id C5A48FFC8D; Tue, 5 May 2020 16:14:22 +0200 (CEST) Message-Id: <20200505134340.902709267@linutronix.de> User-Agent: quilt/0.65 Date: Tue, 05 May 2020 15:41:20 +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 Subject: [patch V4 part 2 08/18] lib/smp_processor_id: Move it into noinstr section References: <20200505134112.272268764@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 That code is already not traceable. Move it into the noinstr section so the objtool section validation does not trigger. Annotate the warning code as "safe". While it might be not under all circumstances, getting the information out is important enough. Should this ever trigger from the sensitive code which is shielded against instrumentation, e.g. low level entry, then the printk is the least of the worries. Addresses the objtool warnings: vmlinux.o: warning: objtool: context_tracking_recursion_enter()+0x7: call to __this_cpu_preempt_check() leaves .noinstr.text section vmlinux.o: warning: objtool: __context_tracking_exit()+0x17: call to __this_cpu_preempt_check() leaves .noinstr.text section vmlinux.o: warning: objtool: __context_tracking_enter()+0x2a: call to __this_cpu_preempt_check() leaves .noinstr.text section Signed-off-by: Thomas Gleixner --- lib/smp_processor_id.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/lib/smp_processor_id.c +++ b/lib/smp_processor_id.c @@ -8,7 +8,7 @@ #include #include -notrace static nokprobe_inline +noinstr static unsigned int check_preemption_disabled(const char *what1, const char *what2) { int this_cpu = raw_smp_processor_id(); @@ -37,6 +37,7 @@ unsigned int check_preemption_disabled(c */ preempt_disable_notrace(); + instr_begin(); if (!printk_ratelimit()) goto out_enable; @@ -45,6 +46,7 @@ unsigned int check_preemption_disabled(c printk("caller is %pS\n", __builtin_return_address(0)); dump_stack(); + instr_end(); out_enable: preempt_enable_no_resched_notrace(); @@ -52,16 +54,14 @@ unsigned int check_preemption_disabled(c return this_cpu; } -notrace unsigned int debug_smp_processor_id(void) +noinstr unsigned int debug_smp_processor_id(void) { return check_preemption_disabled("smp_processor_id", ""); } EXPORT_SYMBOL(debug_smp_processor_id); -NOKPROBE_SYMBOL(debug_smp_processor_id); -notrace void __this_cpu_preempt_check(const char *op) +noinstr void __this_cpu_preempt_check(const char *op) { check_preemption_disabled("__this_cpu_", op); } EXPORT_SYMBOL(__this_cpu_preempt_check); -NOKPROBE_SYMBOL(__this_cpu_preempt_check);