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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 A7188C11D3D for ; Thu, 27 Feb 2020 15:53:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77A47246A0 for ; Thu, 27 Feb 2020 15:53:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729831AbgB0PxT (ORCPT ); Thu, 27 Feb 2020 10:53:19 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:34680 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729110AbgB0PxS (ORCPT ); Thu, 27 Feb 2020 10:53:18 -0500 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 1j7LTB-0000G5-Ed; Thu, 27 Feb 2020 16:53:01 +0100 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 27C2C1040A9; Thu, 27 Feb 2020 16:53:00 +0100 (CET) From: Thomas Gleixner To: Alexandre Chartre , LKML Cc: x86@kernel.org, Steven Rostedt , Brian Gerst , Juergen Gross , Paolo Bonzini , Arnd Bergmann Subject: Re: [patch 5/8] x86/entry/common: Provide trace/kprobe safe exit to user space functions In-Reply-To: <71271e39-1dbd-0bd6-2435-fc8a30f47b7d@oracle.com> References: <20200225220801.571835584@linutronix.de> <20200225221305.719921962@linutronix.de> <71271e39-1dbd-0bd6-2435-fc8a30f47b7d@oracle.com> Date: Thu, 27 Feb 2020 16:53:00 +0100 Message-ID: <87h7zcm3hf.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 Alexandre Chartre writes: > On 2/25/20 11:08 PM, Thomas Gleixner wrote: >> Split prepare_enter_to_user_mode() and mark it notrace/noprobe so the irq >> flags tracing on return can be put into it. > > This splits prepare_exit_to_usermode() not prepare_enter_to_user_mode(). Ooops >> /* Called with IRQs disabled. */ >> -__visible inline void prepare_exit_to_usermode(struct pt_regs *regs) >> +static inline void __prepare_exit_to_usermode(struct pt_regs *regs) >> { >> struct thread_info *ti = current_thread_info(); >> u32 cached_flags; >> @@ -241,6 +241,12 @@ static void exit_to_usermode_loop(struct >> mds_user_clear_cpu_buffers(); >> } >> >> +__visible inline notrace void prepare_exit_to_usermode(struct pt_regs *regs) >> +{ >> + __prepare_exit_to_usermode(regs); >> +} >> +NOKPROBE_SYMBOL(prepare_exit_to_usermode); > > > Would it be worth grouping local_irq_disable() and prepare_exit_to_usermode() > (similarly to what was done entry with syscall_entry_fixups()) and then put > trace_hardirqs_on() there too. For example: > > static __always_inline void syscall_exit_fixups(struct pt_regs *regs) > { > local_irq_disable(); > prepare_exit_to_usermode(regs); > trace_hardirqs_on(); > } > > Or is this planned once prepare_exit_from_usermode() is not used by idtentry > anymore? This should be consolidated at the very end when all the interrupt muck is done, but maybe I forgot.