tile: ensure interrupts disabled for preempt_schedule_irq()

When coming from a page fault (for example), interrupts might
be enabled as we enter the code to return from interrupt.

Cc: stable@vger.kernel.org
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

arch/tile/kernel/intvec_32.S

@@ -815,6 +815,9 @@ STD_ENTRY(interrupt_return)
 	}
 	bzt     r28, 1f
 	bnz     r29, 1f
+	/* Disable interrupts explicitly for preemption. */
+	IRQ_DISABLE(r20,r21)
+	TRACE_IRQS_OFF
 	jal     preempt_schedule_irq
 	FEEDBACK_REENTER(interrupt_return)
 1:

arch/tile/kernel/intvec_64.S

@@ -841,6 +841,9 @@ STD_ENTRY(interrupt_return)
 	}
 	beqzt   r28, 1f
 	bnez    r29, 1f
+	/* Disable interrupts explicitly for preemption. */
+	IRQ_DISABLE(r20,r21)
+	TRACE_IRQS_OFF
 	jal     preempt_schedule_irq
 	FEEDBACK_REENTER(interrupt_return)
 1: