+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * __cpu_disable runs on the processor to be shutdown.
+ */
+int __cpuexit __cpu_disable(void)
+{
+ unsigned int cpu = smp_processor_id();
+ struct task_struct *p;
+ int ret;
+
+ ret = mach_cpu_disable(cpu);
+ if (ret)
+ return ret;
+
+ /*
+ * Take this CPU offline. Once we clear this, we can't return,
+ * and we must not schedule until we're ready to give up the cpu.
+ */
+ cpu_clear(cpu, cpu_online_map);
+
+ /*
+ * OK - migrate IRQs away from this CPU
+ */
+ migrate_irqs();
+
+ /*
+ * Stop the local timer for this CPU.
+ */
+ local_timer_stop(cpu);
+
+ /*
+ * Flush user cache and TLB mappings, and then remove this CPU
+ * from the vm mask set of all processes.
+ */
+ flush_cache_all();
+ local_flush_tlb_all();
+
+ read_lock(&tasklist_lock);
+ for_each_process(p) {
+ if (p->mm)
+ cpu_clear(cpu, p->mm->cpu_vm_mask);
+ }
+ read_unlock(&tasklist_lock);
+
+ return 0;
+}
+
+/*
+ * called on the thread which is asking for a CPU to be shutdown -
+ * waits until shutdown has completed, or it is timed out.
+ */
+void __cpuexit __cpu_die(unsigned int cpu)
+{
+ if (!platform_cpu_kill(cpu))
+ printk("CPU%u: unable to kill\n", cpu);
+}
+
+/*
+ * Called from the idle thread for the CPU which has been shutdown.
+ *
+ * Note that we disable IRQs here, but do not re-enable them
+ * before returning to the caller. This is also the behaviour
+ * of the other hotplug-cpu capable cores, so presumably coming
+ * out of idle fixes this.
+ */
+void __cpuexit cpu_die(void)
+{
+ unsigned int cpu = smp_processor_id();
+
+ local_irq_disable();
+ idle_task_exit();
+
+ /*
+ * actual CPU shutdown procedure is at least platform (if not
+ * CPU) specific
+ */
+ platform_cpu_die(cpu);
+
+ /*
+ * Do not return to the idle loop - jump back to the secondary
+ * cpu initialisation. There's some initialisation which needs
+ * to be repeated to undo the effects of taking the CPU offline.
+ */
+ __asm__("mov sp, %0\n"
+ " b secondary_start_kernel"
+ :
+ : "r" (task_stack_page(current) + THREAD_SIZE - 8));
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+/*
+ * This is the secondary CPU boot entry. We're using this CPUs
+ * idle thread stack, but a set of temporary page tables.
+ */
+asmlinkage void __cpuinit secondary_start_kernel(void)
+{
+ struct mm_struct *mm = &init_mm;
+ unsigned int cpu = smp_processor_id();
+
+ printk("CPU%u: Booted secondary processor\n", cpu);
+
+ /*
+ * All kernel threads share the same mm context; grab a
+ * reference and switch to it.
+ */
+ atomic_inc(&mm->mm_users);
+ atomic_inc(&mm->mm_count);
+ current->active_mm = mm;
+ cpu_set(cpu, mm->cpu_vm_mask);
+ cpu_switch_mm(mm->pgd, mm);
+ enter_lazy_tlb(mm, current);
+ local_flush_tlb_all();
+
+ cpu_init();
+ preempt_disable();
+
+ /*
+ * Give the platform a chance to do its own initialisation.
+ */
+ platform_secondary_init(cpu);
+
+ /*
+ * Enable local interrupts.
+ */
+ local_irq_enable();
+ local_fiq_enable();
+
+ calibrate_delay();
+
+ smp_store_cpu_info(cpu);
+
+ /*
+ * OK, now it's safe to let the boot CPU continue
+ */
+ cpu_set(cpu, cpu_online_map);
+
+ /*
+ * Setup local timer for this CPU.
+ */
+ local_timer_setup(cpu);
+
+ /*
+ * OK, it's off to the idle thread for us
+ */
+ cpu_idle();
+}
+