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=-8.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT 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 EC142C65BAF for ; Wed, 12 Dec 2018 16:48:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA5AE2084E for ; Wed, 12 Dec 2018 16:48:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BA5AE2084E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728226AbeLLQs5 (ORCPT ); Wed, 12 Dec 2018 11:48:57 -0500 Received: from foss.arm.com ([217.140.101.70]:44746 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728160AbeLLQsm (ORCPT ); Wed, 12 Dec 2018 11:48:42 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 309A71688; Wed, 12 Dec 2018 08:48:42 -0800 (PST) Received: from e112298-lin.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 37B4C3F575; Wed, 12 Dec 2018 08:48:40 -0800 (PST) From: Julien Thierry To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, daniel.thompson@linaro.org, joel@joelfernandes.org, marc.zyngier@arm.com, christoffer.dall@arm.com, james.morse@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, mark.rutland@arm.com, Julien Thierry Subject: [PATCH v7 23/25] arm64: Skip preemption when exiting an NMI Date: Wed, 12 Dec 2018 16:47:23 +0000 Message-Id: <1544633245-6036-24-git-send-email-julien.thierry@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1544633245-6036-1-git-send-email-julien.thierry@arm.com> References: <1544633245-6036-1-git-send-email-julien.thierry@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Handling of an NMI should not set any TIF flags. For NMIs received from EL0 the current exit path is safe to use. However, an NMI received at EL1 could have interrupted some task context that has set the TIF_NEED_RESCHED flag. Preempting a task should not happen as a result of an NMI. Skip preemption after handling an NMI from EL1. Signed-off-by: Julien Thierry Cc: Catalin Marinas Cc: Will Deacon Cc: Marc Zyngier --- arch/arm64/kernel/entry.S | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 2804c81..7c9555c 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -637,6 +637,14 @@ el1_irq: #ifdef CONFIG_PREEMPT ldr w24, [tsk, #TSK_TI_PREEMPT] // get preempt count +alternative_if ARM64_HAS_IRQ_PRIO_MASKING + /* + * DA_F were cleared at start of handling. If anything is set in DAIF, + * we come back from an NMI, so skip preemption + */ + mrs x0, daif + orr w24, w24, w0 +alternative_else_nop_endif cbnz w24, 1f // preempt count != 0 ldr x0, [tsk, #TSK_TI_FLAGS] // get flags tbz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling? -- 1.9.1 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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT 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 A1605C65BAF for ; Wed, 12 Dec 2018 16:53:23 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 63D2D2080F for ; Wed, 12 Dec 2018 16:53:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="kRunL3I/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 63D2D2080F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=+kZwWWKamtgWeJ3jQMkcv2cesZ0NQM83GSxZSsiBFPs=; b=kRunL3I/ouD7QA5/VfabU/g8Cl BU+5vZwST+xGwMdRwgoQvXrlUIHATJBD81mJaLv7eHWm7UUE6O+8W4j8hUVTMGHWdGVsO+PxrOuCM k04uJWrZooGVKmDg8il3lHMsvsfCIkv/cvgWUgkmvGqh/G140/XlVxvtMXR8lhGhk3/fqSFHUnQQb Xo/4oyGP7RMgIW/Di27/4L0yYjdBrImaMMhMOWrm2dahTi8OmJ4uiwCFyW2icqFaQj8nhv+1PAt2C +by51UJvl1ajhBRimaX9T4PozXGDfexN3H2rtBJpS+/cROubUIpoSlF+cYSszQtNmzbQpefdpy8sM rfChVmXw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gX7l7-0000Fg-IE; Wed, 12 Dec 2018 16:53:17 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gX7gq-000390-Bc for linux-arm-kernel@lists.infradead.org; Wed, 12 Dec 2018 16:49:08 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 309A71688; Wed, 12 Dec 2018 08:48:42 -0800 (PST) Received: from e112298-lin.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 37B4C3F575; Wed, 12 Dec 2018 08:48:40 -0800 (PST) From: Julien Thierry To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v7 23/25] arm64: Skip preemption when exiting an NMI Date: Wed, 12 Dec 2018 16:47:23 +0000 Message-Id: <1544633245-6036-24-git-send-email-julien.thierry@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1544633245-6036-1-git-send-email-julien.thierry@arm.com> References: <1544633245-6036-1-git-send-email-julien.thierry@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181212_084853_041915_49683F24 X-CRM114-Status: GOOD ( 10.05 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, daniel.thompson@linaro.org, Julien Thierry , marc.zyngier@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, christoffer.dall@arm.com, james.morse@arm.com, joel@joelfernandes.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Handling of an NMI should not set any TIF flags. For NMIs received from EL0 the current exit path is safe to use. However, an NMI received at EL1 could have interrupted some task context that has set the TIF_NEED_RESCHED flag. Preempting a task should not happen as a result of an NMI. Skip preemption after handling an NMI from EL1. Signed-off-by: Julien Thierry Cc: Catalin Marinas Cc: Will Deacon Cc: Marc Zyngier --- arch/arm64/kernel/entry.S | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 2804c81..7c9555c 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -637,6 +637,14 @@ el1_irq: #ifdef CONFIG_PREEMPT ldr w24, [tsk, #TSK_TI_PREEMPT] // get preempt count +alternative_if ARM64_HAS_IRQ_PRIO_MASKING + /* + * DA_F were cleared at start of handling. If anything is set in DAIF, + * we come back from an NMI, so skip preemption + */ + mrs x0, daif + orr w24, w24, w0 +alternative_else_nop_endif cbnz w24, 1f // preempt count != 0 ldr x0, [tsk, #TSK_TI_FLAGS] // get flags tbz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling? -- 1.9.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel