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Commit 1234ad68 authored by Julien Thierry's avatar Julien Thierry Committed by Catalin Marinas
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arm64: Skip preemption when exiting an NMI 



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: default avatarJulien Thierry <julien.thierry@arm.com>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 7d31464a

arch/arm64/kernel/entry.S

+9 −1
Original line number Diff line number Diff line
@@ -624,7 +624,15 @@ el1_irq: 


#ifdef CONFIG_PREEMPT

	ldr	x24, [tsk, #TSK_TI_PREEMPT]	// get preempt count

	cbnz	x24, 1f				// preempt count != 0

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 || NMI return path

	bl	preempt_schedule_irq		// irq en/disable is done inside

1:

#endif