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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 B2B32C433E1 for ; Tue, 19 May 2020 19:59:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9CAF621508 for ; Tue, 19 May 2020 19:59:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728316AbgEST7A (ORCPT ); Tue, 19 May 2020 15:59:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52024 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728199AbgEST6s (ORCPT ); Tue, 19 May 2020 15:58:48 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 42C44C08C5C0; Tue, 19 May 2020 12:58:48 -0700 (PDT) Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jb8Nv-0008Rd-8a; Tue, 19 May 2020 21:58:43 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id BC4AB1C0178; Tue, 19 May 2020 21:58:35 +0200 (CEST) Date: Tue, 19 May 2020 19:58:35 -0000 From: "tip-bot2 for Thomas Gleixner" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/entry] x86/entry/common: Provide idtentry_enter/exit() Cc: Thomas Gleixner , Alexandre Chartre , Peter Zijlstra , Andy Lutomirski , x86 , LKML In-Reply-To: <20200505134904.457578656@linutronix.de> References: <20200505134904.457578656@linutronix.de> MIME-Version: 1.0 Message-ID: <158991831562.17951.6216563865898704227.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit 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 The following commit has been merged into the x86/entry branch of tip: Commit-ID: eadb831607477ba774b3314bdc956331b41817d6 Gitweb: https://git.kernel.org/tip/eadb831607477ba774b3314bdc956331b41817d6 Author: Thomas Gleixner AuthorDate: Thu, 26 Mar 2020 16:28:52 +01:00 Committer: Thomas Gleixner CommitterDate: Tue, 19 May 2020 16:03:57 +02:00 x86/entry/common: Provide idtentry_enter/exit() Provide functions which handle the low level entry and exit similar to enter/exit from user mode. Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Acked-by: Peter Zijlstra Acked-by: Andy Lutomirski Link: https://lkml.kernel.org/r/20200505134904.457578656@linutronix.de --- arch/x86/entry/common.c | 99 +++++++++++++++++++++++++++++++- arch/x86/include/asm/idtentry.h | 3 +- 2 files changed, 102 insertions(+) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index e4f9f5f..9ebe334 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -510,3 +510,102 @@ SYSCALL_DEFINE0(ni_syscall) { return -ENOSYS; } + +/** + * idtentry_enter - Handle state tracking on idtentry + * @regs: Pointer to pt_regs of interrupted context + * + * Invokes: + * - lockdep irqflag state tracking as low level ASM entry disabled + * interrupts. + * + * - Context tracking if the exception hit user mode. + * + * - RCU notification if the exception hit kernel mode. + * + * - The hardirq tracer to keep the state consistent as low level ASM + * entry disabled interrupts. + */ +void noinstr idtentry_enter(struct pt_regs *regs) +{ + if (user_mode(regs)) { + enter_from_user_mode(); + } else { + lockdep_hardirqs_off(CALLER_ADDR0); + rcu_irq_enter(); + instrumentation_begin(); + trace_hardirqs_off_prepare(); + instrumentation_end(); + } +} + +/** + * idtentry_exit - Common code to handle return from exceptions + * @regs: Pointer to pt_regs (exception entry regs) + * + * Depending on the return target (kernel/user) this runs the necessary + * preemption and work checks if possible and required and returns to + * the caller with interrupts disabled and no further work pending. + * + * This is the last action before returning to the low level ASM code which + * just needs to return to the appropriate context. + * + * Invoked by all exception/interrupt IDTENTRY handlers which are not + * returning through the paranoid exit path (all except NMI, #DF and the IST + * variants of #MC and #DB) and are therefore on the thread stack. + */ +void noinstr idtentry_exit(struct pt_regs *regs) +{ + lockdep_assert_irqs_disabled(); + + /* Check whether this returns to user mode */ + if (user_mode(regs)) { + prepare_exit_to_usermode(regs); + } else if (regs->flags & X86_EFLAGS_IF) { + /* 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()) { + if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) + WARN_ON_ONCE(!on_thread_stack()); + instrumentation_begin(); + 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); + instrumentation_end(); + rcu_irq_exit(); + lockdep_hardirqs_on(CALLER_ADDR0); + } else { + /* IRQ flags state is correct already. Just tell RCU */ + rcu_irq_exit(); + } +} diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index bbd81e2..2adfd80 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -7,6 +7,9 @@ #ifndef __ASSEMBLY__ +void idtentry_enter(struct pt_regs *regs); +void idtentry_exit(struct pt_regs *regs); + /** * DECLARE_IDTENTRY - Declare functions for simple IDT entry points * No error code pushed by hardware