From 1234ad686fb1bde5a9c2447fc4c9df8430358763 Mon Sep 17 00:00:00 2001 From: Julien Thierry Date: Thu, 31 Jan 2019 14:59:01 +0000 Subject: [PATCH] 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: Julien Thierry Acked-by: Marc Zyngier Cc: Will Deacon Cc: Marc Zyngier Signed-off-by: Catalin Marinas --- arch/arm64/kernel/entry.S | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 02f809a5c823..35ed48469506 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -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 -- 2.11.0