arm64: Fix interrupt tracing in the presence of NMIs

In the presence of any form of instrumentation, nmi_enter() should be
done before calling any traceable code and any instrumentation code.

Currently, nmi_enter() is done in handle_domain_nmi(), which is much
too late as instrumentation code might get called before. Move the
nmi_enter/exit() calls to the arch IRQ vector handler.

On arm64, it is not possible to know if the IRQ vector handler was
called because of an NMI before acknowledging the interrupt. However, It
is possible to know whether normal interrupts could be taken in the
interrupted context (i.e. if taking an NMI in that context could
introduce a potential race condition).

When interrupting a context with IRQs disabled, call nmi_enter() as soon
as possible. In contexts with IRQs enabled, defer this to the interrupt
controller, which is in a better position to know if an interrupt taken
is an NMI.

Fixes: bc3c03ccb464 ("arm64: Enable the support of pseudo-NMIs")
Cc: <stable@vger.kernel.org> # 5.1.x-
Cc: Will Deacon <will.deacon@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index c52b737ab8e3..a92b33593b8d 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -680,6 +680,8 @@ int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq,
  * @hwirq:	The HW irq number to convert to a logical one
  * @regs:	Register file coming from the low-level handling code
  *
+ *		This function must be called from an NMI context.
+ *
  * Returns:	0 on success, or -EINVAL if conversion has failed
  */
 int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq,
@@ -689,7 +691,10 @@ int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq,
 	unsigned int irq;
 	int ret = 0;
 
-	nmi_enter();
+	/*
+	 * NMI context needs to be setup earlier in order to deal with tracing.
+	 */
+	WARN_ON(!in_nmi());
 
 	irq = irq_find_mapping(domain, hwirq);
 
@@ -702,7 +707,6 @@ int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq,
 	else
 		ret = -EINVAL;
 
-	nmi_exit();
 	set_irq_regs(old_regs);
 	return ret;
 }