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=-14.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 498A7C43461 for ; Fri, 4 Sep 2020 13:19:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 179C12074D for ; Fri, 4 Sep 2020 13:19:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Hr+jYh0O"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="+28Ki0TH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730450AbgIDNTs (ORCPT ); Fri, 4 Sep 2020 09:19:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730379AbgIDNQQ (ORCPT ); Fri, 4 Sep 2020 09:16:16 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A988C061249; Fri, 4 Sep 2020 06:16:16 -0700 (PDT) Date: Fri, 04 Sep 2020 13:16:08 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1599225369; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EDm/8lwmDPTF9yn4NOZs0HVabUPkEA9sgGYYJ1ycOhw=; b=Hr+jYh0OLNBN6dmjVIKsFT3jsBHOUxFzyJZa41reBlevD/kVL1EJpHolvDFVRNSMSO5whn 8IS6XwGjyuh2O23FLwyoSf3LxANb7eKi3pPh4XohV57bvPH5i1kXH99ufVD2xJZwYVBHNR xB12yDGXP/L4C5PnPiih3R/oKHxKPNt5q6Xw9lbnPBgPGcvH7iEQ3LoUb/lNeehSuQls+X 3z9GeqgqVPvf/DTWBgnYD8aAtTi4UkNfm8Wft7H+W7kWBDgnMb8KeGgnvI/+xP42Aj8mLc WsUOK4hgECMJGUwHgySikhTDb3IaMEf3hIppD04Mq94m35Vc/tVE1kWRdwXRHg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1599225369; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EDm/8lwmDPTF9yn4NOZs0HVabUPkEA9sgGYYJ1ycOhw=; b=+28Ki0THbmtJzNKviYmV2ukShV9FZhyvKRTr0WEE9DSoX0pzCV9KmWBSL519LZgkP2Mw6S hv3zy/GxuUGs0GBQ== From: "tip-bot2 for Peter Zijlstra" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/entry] x86/debug: Move historical SYSENTER junk into exc_debug_kernel() Cc: "Peter Zijlstra (Intel)" , Thomas Gleixner , Daniel Thompson , x86 , LKML In-Reply-To: <20200902133201.031099736@infradead.org> References: <20200902133201.031099736@infradead.org> MIME-Version: 1.0 Message-ID: <159922536893.20229.7238736483241139926.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit 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: 4eb5acc39187a7ba578fbb44f7bb1965057309ae Gitweb: https://git.kernel.org/tip/4eb5acc39187a7ba578fbb44f7bb1965057309ae Author: Peter Zijlstra AuthorDate: Wed, 02 Sep 2020 15:25:56 +02:00 Committer: Thomas Gleixner CommitterDate: Fri, 04 Sep 2020 15:12:53 +02:00 x86/debug: Move historical SYSENTER junk into exc_debug_kernel() The historical SYSENTER junk is explicitly for from-kernel, so move it to the #DB-from-kernel handler. It is ordered after the notifier, which is important for KGDB which uses TF single-step and needs to consume the event before that point. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Tested-by: Daniel Thompson Link: https://lore.kernel.org/r/20200902133201.031099736@infradead.org --- arch/x86/kernel/traps.c | 49 ++++++++++++++++++++-------------------- 1 file changed, 25 insertions(+), 24 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 24e09f8..2605686 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -783,7 +783,7 @@ static __always_inline unsigned long debug_read_clear_dr6(void) * * May run on IST stack. */ -static void handle_debug(struct pt_regs *regs, unsigned long dr6) +static bool handle_debug(struct pt_regs *regs, unsigned long *dr6) { struct task_struct *tsk = current; bool icebp; @@ -793,15 +793,13 @@ static void handle_debug(struct pt_regs *regs, unsigned long dr6) * then it's very likely the result of an icebp/int01 trap. * User wants a sigtrap for that. */ - icebp = !dr6; + icebp = !*dr6; /* Store the virtualized DR6 value */ - tsk->thread.debugreg6 = dr6; + tsk->thread.debugreg6 = *dr6; - if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, 0, - SIGTRAP) == NOTIFY_STOP) { - return; - } + if (notify_die(DIE_DEBUG, "debug", regs, (long)dr6, 0, SIGTRAP) == NOTIFY_STOP) + return true; /* It's safe to allow irq's after DR6 has been saved */ cond_local_irq_enable(regs); @@ -815,25 +813,15 @@ static void handle_debug(struct pt_regs *regs, unsigned long dr6) /* * Reload dr6, the notifier might have changed it. */ - dr6 = tsk->thread.debugreg6; + *dr6 = tsk->thread.debugreg6; - if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) { - /* - * Historical junk that used to handle SYSENTER single-stepping. - * This should be unreachable now. If we survive for a while - * without anyone hitting this warning, we'll turn this into - * an oops. - */ - tsk->thread.debugreg6 &= ~DR_STEP; - set_tsk_thread_flag(tsk, TIF_SINGLESTEP); - regs->flags &= ~X86_EFLAGS_TF; - } - - if (dr6 & (DR_STEP | DR_TRAP_BITS) || icebp) - send_sigtrap(regs, 0, get_si_code(dr6)); + if (*dr6 & (DR_STEP | DR_TRAP_BITS) || icebp) + send_sigtrap(regs, 0, get_si_code(*dr6)); out: cond_local_irq_disable(regs); + + return false; } static __always_inline void exc_debug_kernel(struct pt_regs *regs, @@ -876,7 +864,20 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs, if (!dr6) goto out; - handle_debug(regs, dr6); + if (handle_debug(regs, &dr6)) + goto out; + + if (WARN_ON_ONCE(dr6 & DR_STEP)) { + /* + * Historical junk that used to handle SYSENTER single-stepping. + * This should be unreachable now. If we survive for a while + * without anyone hitting this warning, we'll turn this into + * an oops. + */ + dr6 &= ~DR_STEP; + set_thread_flag(TIF_SINGLESTEP); + regs->flags &= ~X86_EFLAGS_TF; + } out: instrumentation_end(); @@ -906,7 +907,7 @@ static __always_inline void exc_debug_user(struct pt_regs *regs, irqentry_enter_from_user_mode(regs); instrumentation_begin(); - handle_debug(regs, dr6); + handle_debug(regs, &dr6); instrumentation_end(); irqentry_exit_to_user_mode(regs);