powerpc/kexec: Disable hard IRQ before kexec

commit 8520e443 upstream.

Disable hard IRQ before kexec a new kernel image.
Not doing it can result in corrupted data in the memory segments
reserved for the new kernel.
Signed-off-by: Phileas Fogg <phileas-fogg@mail.ru>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/powerpc/kernel/machine_kexec_64.c

@@ -162,6 +162,8 @@ static int kexec_all_irq_disabled = 0;
 static void kexec_smp_down(void *arg)
 {
 	local_irq_disable();
+	hard_irq_disable();
+
 	mb(); /* make sure our irqs are disabled before we say they are */
 	get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
 	while(kexec_all_irq_disabled == 0)
@@ -244,6 +246,8 @@ static void kexec_prepare_cpus(void)
 	wake_offline_cpus();
 	smp_call_function(kexec_smp_down, NULL, /* wait */0);
 	local_irq_disable();
+	hard_irq_disable();
+
 	mb(); /* make sure IRQs are disabled before we say they are */
 	get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
 
@@ -281,6 +285,7 @@ static void kexec_prepare_cpus(void)
 	if (ppc_md.kexec_cpu_down)
 		ppc_md.kexec_cpu_down(0, 0);
 	local_irq_disable();
+	hard_irq_disable();
 }
 
 #endif /* SMP */