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From: Pingfan Liu <kernelfans@gmail.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Pingfan Liu <kernelfans@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Marc Zyngier <maz@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
	Sami Tolvanen <samitolvanen@google.com>,
	Julien Thierry <julien.thierry@arm.com>,
	Yuichi Ito <ito-yuichi@fujitsu.com>,
	rcu@vger.kernel.org
Subject: [PATCHv3 4/4] arm64: entry: remove pNMI judgement in __el1_interrupt() path
Date: Tue, 16 Nov 2021 16:24:50 +0800	[thread overview]
Message-ID: <20211116082450.10357-5-kernelfans@gmail.com> (raw)
In-Reply-To: <20211116082450.10357-1-kernelfans@gmail.com>

Now, all pNMI can be detected before the dispatching of __el1_pnmi() or
__el1_interrupt(), and __el1_interrupt() will never be called in pNMI
context. As a result, the judgement of pNMI in
arm64_preempt_schedule_irq() becomes unnecessary.

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Julien Thierry <julien.thierry@arm.com>
Cc: Yuichi Ito <ito-yuichi@fujitsu.com>
Cc: rcu@vger.kernel.org
To: linux-arm-kernel@lists.infradead.org
---
 arch/arm64/kernel/entry-common.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index afcde43f1b73..57d654b915a5 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -224,15 +224,6 @@ static void __sched arm64_preempt_schedule_irq(void)
 {
 	lockdep_assert_irqs_disabled();
 
-	/*
-	 * DAIF.DA are cleared at the start of IRQ/FIQ handling, and when GIC
-	 * priority masking is used the GIC irqchip driver will clear DAIF.IF
-	 * using gic_arch_enable_irqs() for normal IRQs. If anything is set in
-	 * DAIF we must have handled an NMI, so skip preemption.
-	 */
-	if (system_uses_irq_prio_masking() && read_sysreg(daif))
-		return;
-
 	/*
 	 * Preempting a task from an IRQ means we leave copies of PSTATE
 	 * on the stack. cpufeature's enable calls may modify PSTATE, but
-- 
2.31.1


WARNING: multiple messages have this Message-ID (diff)
From: Pingfan Liu <kernelfans@gmail.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Pingfan Liu <kernelfans@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Marc Zyngier <maz@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
	Sami Tolvanen <samitolvanen@google.com>,
	Julien Thierry <julien.thierry@arm.com>,
	Yuichi Ito <ito-yuichi@fujitsu.com>,
	rcu@vger.kernel.org
Subject: [PATCHv3 4/4] arm64: entry: remove pNMI judgement in __el1_interrupt() path
Date: Tue, 16 Nov 2021 16:24:50 +0800	[thread overview]
Message-ID: <20211116082450.10357-5-kernelfans@gmail.com> (raw)
In-Reply-To: <20211116082450.10357-1-kernelfans@gmail.com>

Now, all pNMI can be detected before the dispatching of __el1_pnmi() or
__el1_interrupt(), and __el1_interrupt() will never be called in pNMI
context. As a result, the judgement of pNMI in
arm64_preempt_schedule_irq() becomes unnecessary.

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Julien Thierry <julien.thierry@arm.com>
Cc: Yuichi Ito <ito-yuichi@fujitsu.com>
Cc: rcu@vger.kernel.org
To: linux-arm-kernel@lists.infradead.org
---
 arch/arm64/kernel/entry-common.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index afcde43f1b73..57d654b915a5 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -224,15 +224,6 @@ static void __sched arm64_preempt_schedule_irq(void)
 {
 	lockdep_assert_irqs_disabled();
 
-	/*
-	 * DAIF.DA are cleared at the start of IRQ/FIQ handling, and when GIC
-	 * priority masking is used the GIC irqchip driver will clear DAIF.IF
-	 * using gic_arch_enable_irqs() for normal IRQs. If anything is set in
-	 * DAIF we must have handled an NMI, so skip preemption.
-	 */
-	if (system_uses_irq_prio_masking() && read_sysreg(daif))
-		return;
-
 	/*
 	 * Preempting a task from an IRQ means we leave copies of PSTATE
 	 * on the stack. cpufeature's enable calls may modify PSTATE, but
-- 
2.31.1


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-11-16  8:25 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-16  8:24 [PATCHv3 0/4] arm64: Fixes RCU deadlock due to a mistaken Pingfan Liu
2021-11-16  8:24 ` Pingfan Liu
2021-11-16  8:24 ` [PATCHv3 1/4] arm64: entry: judge nmi ealier to avoid deadlock in RCU Pingfan Liu
2021-11-16  8:24   ` Pingfan Liu
2021-11-17 11:38   ` Mark Rutland
2021-11-17 11:38     ` Mark Rutland
2021-11-19  2:01     ` Pingfan Liu
2021-11-19  2:01       ` Pingfan Liu
2021-11-19 14:04       ` Mark Rutland
2021-11-19 14:04         ` Mark Rutland
2021-11-16  8:24 ` [PATCHv3 2/4] arm64: entry: distinguish pNMI earlier in el0 interrupt Pingfan Liu
2021-11-16  8:24   ` Pingfan Liu
2021-11-16  8:24 ` [PATCHv3 3/4] irqchip: GICv3: expose pNMI discriminator Pingfan Liu
2021-11-16  8:24   ` Pingfan Liu
2021-11-16  9:53   ` Marc Zyngier
2021-11-16  9:53     ` Marc Zyngier
2021-11-17 10:16     ` Pingfan Liu
2021-11-17 10:16       ` Pingfan Liu
2021-11-17 11:01       ` Marc Zyngier
2021-11-17 11:01         ` Marc Zyngier
2021-11-19  2:38         ` Pingfan Liu
2021-11-19  2:38           ` Pingfan Liu
2021-11-16  8:24 ` Pingfan Liu [this message]
2021-11-16  8:24   ` [PATCHv3 4/4] arm64: entry: remove pNMI judgement in __el1_interrupt() path Pingfan Liu

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