[PATCH 1/8] arm64: Use cpu_ops for smp_stop

The current implementation of ipi_cpu_stop() is just a tight infinite loop
around cpu_relax().  Add a check for a valid cpu_die method of the appropriate
cpu_operations structure, and if a valid method is found, transfer control to
that method.

The core kexec code calls the arch specific machine_shutdown() routine to
shutdown any SMP secondary CPUs.  The current implementation of the arm64
machine_shutdown() uses smp_send_stop(), which ultimately runs ipi_cpu_stop()
on the secondary CPUs.  The infinite loop implementation of the current
ipi_cpu_stop() does not have any mechanism to get the CPU into a state
compatable with a kexec re-boot.

Signed-off-by: Geoff Levand <geoff@infradead.org>
---
 arch/arm64/kernel/smp.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index f0a141d..020bbd5 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c

@@ -508,6 +508,14 @@ static void ipi_cpu_stop(unsigned int cpu)
 
 	local_irq_disable();
 
+	/* If we have the cup_ops use them. */
+
+	if (cpu_ops[cpu]->cpu_disable && cpu_ops[cpu]->cpu_die
+		&& !cpu_ops[cpu]->cpu_disable(cpu))
+		cpu_ops[cpu]->cpu_die(cpu);
+
+	/* Spin here if the cup_ops fail. */
+
 	while (1)
 		cpu_relax();
 }

-- 
1.9.1