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,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 B28E6C433E1 for ; Sat, 16 May 2020 00:10:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A03D82078B for ; Sat, 16 May 2020 00:10:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727844AbgEPAKk (ORCPT ); Fri, 15 May 2020 20:10:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41048 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1727817AbgEPAKk (ORCPT ); Fri, 15 May 2020 20:10:40 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0A00DC061A0C for ; Fri, 15 May 2020 17:10:40 -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 1jZkP5-00022O-1o; Sat, 16 May 2020 02:10:11 +0200 Received: from nanos.tec.linutronix.de (localhost [IPv6:::1]) by nanos.tec.linutronix.de (Postfix) with ESMTP id 89899100605; Sat, 16 May 2020 02:10:10 +0200 (CEST) Message-Id: <20200515235124.673436293@linutronix.de> User-Agent: quilt/0.65 Date: Sat, 16 May 2020 01:45:50 +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 , Tom Lendacky , Wei Liu , Michael Kelley , Jason Chen CJ , Zhao Yakui , "Peter Zijlstra (Intel)" Subject: [patch V6 03/37] nmi, tracing: Provide nmi_enter/exit_notrace() References: <20200515234547.710474468@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 To fully isolate #DB and #BP from instrumentable code it's necessary to avoid invoking the hardware latency tracer on nmi_enter/exit(). Provide nmi_enter/exit() variants which are not invoking the hardware latency tracer. That allows to put calls explicitely into the call sites outside of the kprobe handling. Signed-off-by: Thomas Gleixner --- include/linux/hardirq.h | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -76,8 +76,16 @@ extern void irq_exit(void); /* * nmi_enter() can nest up to 15 times; see NMI_BITS. + * + * ftrace_count_nmi() only increments a counter and is noinstr safe so it + * can be invoked in nmi_enter_notrace(). ftrace_nmi_handler_enter/exit() + * does time stamping and will be invoked in the actual NMI handling after + * an instrumentable section has been reached. + * + * nmi_enter/exit() still calls into the tracer so existing callers + * wont break. */ -#define nmi_enter() \ +#define nmi_enter_notrace() \ do { \ arch_nmi_enter(); \ printk_nmi_enter(); \ @@ -87,10 +95,15 @@ extern void irq_exit(void); rcu_nmi_enter(); \ lockdep_hardirq_enter(); \ ftrace_count_nmi(); \ + } while (0) + +#define nmi_enter() \ + do { \ + nmi_enter_notrace(); \ ftrace_nmi_handler_enter(); \ } while (0) -#define nmi_exit() \ +#define nmi_exit_notrace() \ do { \ ftrace_nmi_handler_exit(); \ lockdep_hardirq_exit(); \ @@ -102,4 +115,10 @@ extern void irq_exit(void); arch_nmi_exit(); \ } while (0) +#define nmi_exit() \ + do { \ + ftrace_nmi_handler_exit(); \ + nmi_exit_notrace(); \ + } while (0) + #endif /* LINUX_HARDIRQ_H */