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 7D88AC433E3 for ; Thu, 21 May 2020 20:31:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 633D021508 for ; Thu, 21 May 2020 20:31:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729821AbgEUUb5 (ORCPT ); Thu, 21 May 2020 16:31:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729634AbgEUUby (ORCPT ); Thu, 21 May 2020 16:31:54 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 70EEBC061A0E for ; Thu, 21 May 2020 13:31:54 -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 1jbrqd-0000M3-JI; Thu, 21 May 2020 22:31:23 +0200 Received: from nanos.tec.linutronix.de (localhost [IPv6:::1]) by nanos.tec.linutronix.de (Postfix) with ESMTP id 1AB7C100C2D; Thu, 21 May 2020 22:31:22 +0200 (CEST) Message-Id: <20200521202117.473597954@linutronix.de> User-Agent: quilt/0.65 Date: Thu, 21 May 2020 22:05:20 +0200 From: Thomas Gleixner To: LKML Cc: Andy Lutomirski , Andrew Cooper , X86 ML , "Paul E. McKenney" , 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 V9 07/39] x86/entry: Cleanup idtentry_enter/exit() leftovers References: <20200521200513.656533920@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 Now that everything is converted to conditional RCU handling remove idtentry_enter/exit() and tidy up the conditional functions. This does not remove rcu_irq_exit_preempt() to avoid conflicts with the RCU tree. Will be removed once all of this hit Linus tree. Signed-off-by: Thomas Gleixner --- V9: New patch --- arch/x86/entry/common.c | 67 +++++++++++++++++----------------------- arch/x86/include/asm/idtentry.h | 12 ------- 2 files changed, 30 insertions(+), 49 deletions(-) --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -515,7 +515,6 @@ SYSCALL_DEFINE0(ni_syscall) * idtentry_enter_cond_rcu - Handle state tracking on idtentry with conditional * RCU handling * @regs: Pointer to pt_regs of interrupted context - * @cond_rcu: Invoke rcu_irq_enter() only if RCU is not watching * * Invokes: * - lockdep irqflag state tracking as low level ASM entry disabled @@ -545,12 +544,12 @@ SYSCALL_DEFINE0(ni_syscall) * The return value must be fed into the rcu_exit argument of * idtentry_exit_cond_rcu(). */ -bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs, bool cond_rcu) +bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs) { if (user_mode(regs)) { enter_from_user_mode(); } else { - if (!cond_rcu || !__rcu_is_watching()) { + if (!__rcu_is_watching()) { /* * If RCU is not watching then the same careful * sequence vs. lockdep and tracing is required @@ -605,52 +604,44 @@ void noinstr idtentry_exit_cond_rcu(stru if (user_mode(regs)) { prepare_exit_to_usermode(regs); } else if (regs->flags & X86_EFLAGS_IF) { + /* + * If RCU was not watching on entry this needs to be done + * carefully and needs the same ordering of lockdep/tracing + * and RCU as the return to user mode path. + */ + if (rcu_exit) { + instrumentation_begin(); + /* Tell the tracer that IRET will enable interrupts */ + trace_hardirqs_on_prepare(); + lockdep_hardirqs_on_prepare(CALLER_ADDR0); + instrumentation_end(); + rcu_irq_exit(); + lockdep_hardirqs_on(CALLER_ADDR0); + return; + } + + instrumentation_begin(); + /* Check kernel preemption, if enabled */ if (IS_ENABLED(CONFIG_PREEMPTION)) { - /* - * This needs to be done very carefully. - * idtentry_enter() invoked rcu_irq_enter(). This - * needs to be undone before scheduling. - * - * Preemption is disabled inside of RCU idle - * sections. When the task returns from - * preempt_schedule_irq(), RCU is still watching. - * - * rcu_irq_exit_preempt() has additional state - * checking if CONFIG_PROVE_RCU=y - */ if (!preempt_count()) { + /* Sanity check RCU and thread stack */ + rcu_irq_exit_check_preempt(); if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) WARN_ON_ONCE(!on_thread_stack()); - instrumentation_begin(); - if (rcu_exit) - rcu_irq_exit_preempt(); if (need_resched()) preempt_schedule_irq(); - /* Covers both tracing and lockdep */ - trace_hardirqs_on(); - instrumentation_end(); - return; } } - /* - * If preemption is disabled then this needs to be done - * carefully with respect to RCU. The exception might come - * from a RCU idle section in the idle task due to the fact - * that safe_halt() enables interrupts. So this needs the - * same ordering of lockdep/tracing and RCU as the return - * to user mode path. - */ - instrumentation_begin(); - /* Tell the tracer that IRET will enable interrupts */ - trace_hardirqs_on_prepare(); - lockdep_hardirqs_on_prepare(CALLER_ADDR0); + /* Covers both tracing and lockdep */ + trace_hardirqs_on(); + instrumentation_end(); - if (rcu_exit) - rcu_irq_exit(); - lockdep_hardirqs_on(CALLER_ADDR0); } else { - /* IRQ flags state is correct already. Just tell RCU. */ + /* + * IRQ flags state is correct already. Just tell RCU if it + * was not watching on entry. + */ if (rcu_exit) rcu_irq_exit(); } --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -10,19 +10,9 @@ void idtentry_enter_user(struct pt_regs *regs); void idtentry_exit_user(struct pt_regs *regs); -bool idtentry_enter_cond_rcu(struct pt_regs *regs, bool cond_rcu); +bool idtentry_enter_cond_rcu(struct pt_regs *regs); void idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit); -static __always_inline void idtentry_enter(struct pt_regs *regs) -{ - idtentry_enter_cond_rcu(regs, false); -} - -static __always_inline void idtentry_exit(struct pt_regs *regs) -{ - idtentry_exit_cond_rcu(regs, true); -} - /** * DECLARE_IDTENTRY - Declare functions for simple IDT entry points * No error code pushed by hardware