arm64: Only enable local interrupts after the CPU is marked online

commit 53ae3acd upstream.

There is a slight chance that (timer) interrupts are triggered before a
secondary CPU has been marked online with implications on softirq thread
affinity.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Kirill Tkhai <tkhai@yandex.ru>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm64/kernel/smp.c

@@ -199,13 +199,6 @@ asmlinkage void __cpuinit secondary_start_kernel(void)
 	raw_spin_lock(&boot_lock);
 	raw_spin_unlock(&boot_lock);
 
-	/*
-	 * Enable local interrupts.
-	 */
-	notify_cpu_starting(cpu);
-	local_irq_enable();
-	local_fiq_enable();
-
 	/*
 	 * OK, now it's safe to let the boot CPU continue.  Wait for
 	 * the CPU migration code to notice that the CPU is online
@@ -214,6 +207,14 @@ asmlinkage void __cpuinit secondary_start_kernel(void)
 	set_cpu_online(cpu, true);
 	complete(&cpu_running);
 
+	/*
+	 * Enable GIC and timers.
+	 */
+	notify_cpu_starting(cpu);
+
+	local_irq_enable();
+	local_fiq_enable();
+
 	/*
 	 * OK, it's off to the idle thread for us
 	 */