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Received: from foss.arm.com ([217.140.101.70]) by merlin.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1ggs3q-0000D1-GD for linux-arm-kernel@lists.infradead.org; Tue, 08 Jan 2019 14:08:55 +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 590A180D; Tue, 8 Jan 2019 06:08:54 -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 5CB0A3F70D; Tue, 8 Jan 2019 06:08:52 -0800 (PST) From: Julien Thierry To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v8 24/26] arm64: Skip preemption when exiting an NMI Date: Tue, 8 Jan 2019 14:07:42 +0000 Message-Id: <1546956464-48825-25-git-send-email-julien.thierry@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1546956464-48825-1-git-send-email-julien.thierry@arm.com> References: <1546956464-48825-1-git-send-email-julien.thierry@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190108_090854_670268_55576BFB X-CRM114-Status: GOOD ( 10.35 ) 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 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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 35a47f6..a0b0a22 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -624,6 +624,14 @@ el1_irq: #ifdef CONFIG_PREEMPT ldr x24, [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 x24, x24, x0 +alternative_else_nop_endif cbnz x24, 1f // preempt count != 0 bl el1_preempt 1: