arch/arm/kernel/smp.c - maze/linux - Git at Google

 /*
  *  linux/arch/arm/kernel/smp.c
  *
  *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
 #include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
 #include <linux/sched.h>
 #include <linux/interrupt.h>
 #include <linux/cache.h>
 #include <linux/profile.h>
 #include <linux/errno.h>
 #include <linux/mm.h>
 #include <linux/err.h>
 #include <linux/cpu.h>
 #include <linux/seq_file.h>
 #include <linux/irq.h>
 #include <linux/percpu.h>
 #include <linux/clockchips.h>
 #include <linux/completion.h>
 #include <linux/cpufreq.h>
 #include <linux/irq_work.h>

 #include <linux/atomic.h>
 #include <asm/smp.h>
 #include <asm/cacheflush.h>
 #include <asm/cpu.h>
 #include <asm/cputype.h>
 #include <asm/exception.h>
 #include <asm/idmap.h>
 #include <asm/topology.h>
 #include <asm/mmu_context.h>
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
 #include <asm/processor.h>
 #include <asm/sections.h>
 #include <asm/tlbflush.h>
 #include <asm/ptrace.h>
 #include <asm/smp_plat.h>
 #include <asm/virt.h>
 #include <asm/mach/arch.h>
 #include <asm/mpu.h>

 /*
  * as from 2.5, kernels no longer have an init_tasks structure
  * so we need some other way of telling a new secondary core
  * where to place its SVC stack
  */
 struct secondary_data secondary_data;

 /*
  * control for which core is the next to come out of the secondary
  * boot "holding pen"
  */
 volatile int pen_release = -1;

 enum ipi_msg_type {
 	IPI_WAKEUP,
 	IPI_TIMER,
 	IPI_RESCHEDULE,
 	IPI_CALL_FUNC,
 	IPI_CALL_FUNC_SINGLE,
 	IPI_CPU_STOP,
 	IPI_IRQ_WORK,
 	IPI_COMPLETION,
 };

 static DECLARE_COMPLETION(cpu_running);

 static struct smp_operations smp_ops;

 void __init smp_set_ops(struct smp_operations *ops)
 {
 	if (ops)
 		smp_ops = *ops;
 };

 static unsigned long get_arch_pgd(pgd_t *pgd)
 {
 	phys_addr_t pgdir = virt_to_idmap(pgd);
 	BUG_ON(pgdir & ARCH_PGD_MASK);
 	return pgdir >> ARCH_PGD_SHIFT;
 }

 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 {
 	int ret;

 	/*
 	 * We need to tell the secondary core where to find
 	 * its stack and the page tables.
 	 */
 	secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
 #ifdef CONFIG_ARM_MPU
 	secondary_data.mpu_rgn_szr = mpu_rgn_info.rgns[MPU_RAM_REGION].drsr;
 #endif

 #ifdef CONFIG_MMU
 	secondary_data.pgdir = get_arch_pgd(idmap_pgd);
 	secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
 #endif
 	sync_cache_w(&secondary_data);

 	/*
 	 * Now bring the CPU into our world.
 	 */
 	ret = boot_secondary(cpu, idle);
 	if (ret == 0) {
 		/*
 		 * CPU was successfully started, wait for it
 		 * to come online or time out.
 		 */
 		wait_for_completion_timeout(&cpu_running,
 						 msecs_to_jiffies(1000));

 		if (!cpu_online(cpu)) {
 			pr_crit("CPU%u: failed to come online\n", cpu);
 			ret = -EIO;
 		}
 	} else {
 		pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
 	}


 	memset(&secondary_data, 0, sizeof(secondary_data));
 	return ret;
 }

 /* platform specific SMP operations */
 void __init smp_init_cpus(void)
 {
 	if (smp_ops.smp_init_cpus)
 		smp_ops.smp_init_cpus();
 }

 int boot_secondary(unsigned int cpu, struct task_struct *idle)
 {
 	if (smp_ops.smp_boot_secondary)
 		return smp_ops.smp_boot_secondary(cpu, idle);
 	return -ENOSYS;
 }

 int platform_can_cpu_hotplug(void)
 {
 #ifdef CONFIG_HOTPLUG_CPU
 	if (smp_ops.cpu_kill)
 		return 1;
 #endif

 	return 0;
 }

 #ifdef CONFIG_HOTPLUG_CPU
 static int platform_cpu_kill(unsigned int cpu)
 {
 	if (smp_ops.cpu_kill)
 		return smp_ops.cpu_kill(cpu);
 	return 1;
 }

 static int platform_cpu_disable(unsigned int cpu)
 {
 	if (smp_ops.cpu_disable)
 		return smp_ops.cpu_disable(cpu);

 	/*
 	 * By default, allow disabling all CPUs except the first one,
 	 * since this is special on a lot of platforms, e.g. because
 	 * of clock tick interrupts.
 	 */
 	return cpu == 0 ? -EPERM : 0;
 }
 /*
  * __cpu_disable runs on the processor to be shutdown.
  */
 int __cpu_disable(void)
 {
 	unsigned int cpu = smp_processor_id();
 	int ret;

 	ret = platform_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.
 	 */
 	set_cpu_online(cpu, false);

 	/*
 	 * OK - migrate IRQs away from this CPU
 	 */
 	migrate_irqs();

 	/*
 	 * Flush user cache and TLB mappings, and then remove this CPU
 	 * from the vm mask set of all processes.
 	 *
 	 * Caches are flushed to the Level of Unification Inner Shareable
 	 * to write-back dirty lines to unified caches shared by all CPUs.
 	 */
 	flush_cache_louis();
 	local_flush_tlb_all();

 	clear_tasks_mm_cpumask(cpu);

 	return 0;
 }

 static DECLARE_COMPLETION(cpu_died);

 /*
  * called on the thread which is asking for a CPU to be shutdown -
  * waits until shutdown has completed, or it is timed out.
  */
 void __cpu_die(unsigned int cpu)
 {
 	if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
 		pr_err("CPU%u: cpu didn't die\n", cpu);
 		return;
 	}
 	printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);

 	/*
 	 * platform_cpu_kill() is generally expected to do the powering off
 	 * and/or cutting of clocks to the dying CPU.  Optionally, this may
 	 * be done by the CPU which is dying in preference to supporting
 	 * this call, but that means there is _no_ synchronisation between
 	 * the requesting CPU and the dying CPU actually losing power.
 	 */
 	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 __ref cpu_die(void)
 {
 	unsigned int cpu = smp_processor_id();

 	idle_task_exit();

 	local_irq_disable();

 	/*
 	 * Flush the data out of the L1 cache for this CPU.  This must be
 	 * before the completion to ensure that data is safely written out
 	 * before platform_cpu_kill() gets called - which may disable
 	 * *this* CPU and power down its cache.
 	 */
 	flush_cache_louis();

 	/*
 	 * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
 	 * this returns, power and/or clocks can be removed at any point
 	 * from this CPU and its cache by platform_cpu_kill().
 	 */
 	complete(&cpu_died);

 	/*
 	 * Ensure that the cache lines associated with that completion are
 	 * written out.  This covers the case where _this_ CPU is doing the
 	 * powering down, to ensure that the completion is visible to the
 	 * CPU waiting for this one.
 	 */
 	flush_cache_louis();

 	/*
 	 * The actual CPU shutdown procedure is at least platform (if not
 	 * CPU) specific.  This may remove power, or it may simply spin.
 	 *
 	 * Platforms are generally expected *NOT* to return from this call,
 	 * although there are some which do because they have no way to
 	 * power down the CPU.  These platforms are the _only_ reason we
 	 * have a return path which uses the fragment of assembly below.
 	 *
 	 * The return path should not be used for platforms which can
 	 * power off the CPU.
 	 */
 	if (smp_ops.cpu_die)
 		smp_ops.cpu_die(cpu);

 	pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 		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"
 	"	mov	fp, #0\n"
 	"	b	secondary_start_kernel"
 		:
 		: "r" (task_stack_page(current) + THREAD_SIZE - 8));
 }
 #endif /* CONFIG_HOTPLUG_CPU */

 /*
  * Called by both boot and secondaries to move global data into
  * per-processor storage.
  */
 static void smp_store_cpu_info(unsigned int cpuid)
 {
 	struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);

 	cpu_info->loops_per_jiffy = loops_per_jiffy;
 	cpu_info->cpuid = read_cpuid_id();

 	store_cpu_topology(cpuid);
 }

 /*
  * This is the secondary CPU boot entry.  We're using this CPUs
  * idle thread stack, but a set of temporary page tables.
  */
 asmlinkage void secondary_start_kernel(void)
 {
 	struct mm_struct *mm = &init_mm;
 	unsigned int cpu;

 	/*
 	 * The identity mapping is uncached (strongly ordered), so
 	 * switch away from it before attempting any exclusive accesses.
 	 */
 	cpu_switch_mm(mm->pgd, mm);
 	local_flush_bp_all();
 	enter_lazy_tlb(mm, current);
 	local_flush_tlb_all();

 	/*
 	 * All kernel threads share the same mm context; grab a
 	 * reference and switch to it.
 	 */
 	cpu = smp_processor_id();
 	atomic_inc(&mm->mm_count);
 	current->active_mm = mm;
 	cpumask_set_cpu(cpu, mm_cpumask(mm));

 	cpu_init();

 	printk("CPU%u: Booted secondary processor\n", cpu);

 	preempt_disable();
 	trace_hardirqs_off();

 	/*
 	 * Give the platform a chance to do its own initialisation.
 	 */
 	if (smp_ops.smp_secondary_init)
 		smp_ops.smp_secondary_init(cpu);

 	notify_cpu_starting(cpu);

 	calibrate_delay();

 	smp_store_cpu_info(cpu);

 	/*
 	 * OK, now it's safe to let the boot CPU continue.  Wait for
 	 * the CPU migration code to notice that the CPU is online
 	 * before we continue - which happens after __cpu_up returns.
 	 */
 	set_cpu_online(cpu, true);
 	complete(&cpu_running);

 	local_irq_enable();
 	local_fiq_enable();

 	/*
 	 * OK, it's off to the idle thread for us
 	 */
 	cpu_startup_entry(CPUHP_ONLINE);
 }

 void __init smp_cpus_done(unsigned int max_cpus)
 {
 	printk(KERN_INFO "SMP: Total of %d processors activated.\n",
 	       num_online_cpus());

 	hyp_mode_check();
 }

 void __init smp_prepare_boot_cpu(void)
 {
 	set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 }

 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
 	unsigned int ncores = num_possible_cpus();

 	init_cpu_topology();

 	smp_store_cpu_info(smp_processor_id());

 	/*
 	 * are we trying to boot more cores than exist?
 	 */
 	if (max_cpus > ncores)
 		max_cpus = ncores;
 	if (ncores > 1 && max_cpus) {
 		/*
 		 * Initialise the present map, which describes the set of CPUs
 		 * actually populated at the present time. A platform should
 		 * re-initialize the map in the platforms smp_prepare_cpus()
 		 * if present != possible (e.g. physical hotplug).
 		 */
 		init_cpu_present(cpu_possible_mask);

 		/*
 		 * Initialise the SCU if there are more than one CPU
 		 * and let them know where to start.
 		 */
 		if (smp_ops.smp_prepare_cpus)
 			smp_ops.smp_prepare_cpus(max_cpus);
 	}
 }

 static void (*smp_cross_call)(const struct cpumask *, unsigned int);

 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
 {
 	if (!smp_cross_call)
 		smp_cross_call = fn;
 }

 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 {
 	smp_cross_call(mask, IPI_CALL_FUNC);
 }

 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 {
 	smp_cross_call(mask, IPI_WAKEUP);
 }

 void arch_send_call_function_single_ipi(int cpu)
 {
 	smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 }

 #ifdef CONFIG_IRQ_WORK
 void arch_irq_work_raise(void)
 {
 	if (is_smp())
 		smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 }
 #endif

 static const char *ipi_types[NR_IPI] = {
 #define S(x,s)	[x] = s
 	S(IPI_WAKEUP, "CPU wakeup interrupts"),
 	S(IPI_TIMER, "Timer broadcast interrupts"),
 	S(IPI_RESCHEDULE, "Rescheduling interrupts"),
 	S(IPI_CALL_FUNC, "Function call interrupts"),
 	S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
 	S(IPI_CPU_STOP, "CPU stop interrupts"),
 	S(IPI_IRQ_WORK, "IRQ work interrupts"),
 	S(IPI_COMPLETION, "completion interrupts"),
 };

 void show_ipi_list(struct seq_file *p, int prec)
 {
 	unsigned int cpu, i;

 	for (i = 0; i < NR_IPI; i++) {
 		seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);

 		for_each_online_cpu(cpu)
 			seq_printf(p, "%10u ",
 				   __get_irq_stat(cpu, ipi_irqs[i]));

 		seq_printf(p, " %s\n", ipi_types[i]);
 	}
 }

 u64 smp_irq_stat_cpu(unsigned int cpu)
 {
 	u64 sum = 0;
 	int i;

 	for (i = 0; i < NR_IPI; i++)
 		sum += __get_irq_stat(cpu, ipi_irqs[i]);

 	return sum;
 }

 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 void tick_broadcast(const struct cpumask *mask)
 {
 	smp_cross_call(mask, IPI_TIMER);
 }
 #endif

 static DEFINE_RAW_SPINLOCK(stop_lock);

 /*
  * ipi_cpu_stop - handle IPI from smp_send_stop()
  */
 static void ipi_cpu_stop(unsigned int cpu)
 {
 	if (system_state == SYSTEM_BOOTING ||
 	    system_state == SYSTEM_RUNNING) {
 		raw_spin_lock(&stop_lock);
 		printk(KERN_CRIT "CPU%u: stopping\n", cpu);
 		dump_stack();
 		raw_spin_unlock(&stop_lock);
 	}

 	set_cpu_online(cpu, false);

 	local_fiq_disable();
 	local_irq_disable();

 	while (1)
 		cpu_relax();
 }

 static DEFINE_PER_CPU(struct completion *, cpu_completion);

 int register_ipi_completion(struct completion *completion, int cpu)
 {
 	per_cpu(cpu_completion, cpu) = completion;
 	return IPI_COMPLETION;
 }

 static void ipi_complete(unsigned int cpu)
 {
 	complete(per_cpu(cpu_completion, cpu));
 }

 /*
  * Main handler for inter-processor interrupts
  */
 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 {
 	handle_IPI(ipinr, regs);
 }

 void handle_IPI(int ipinr, struct pt_regs *regs)
 {
 	unsigned int cpu = smp_processor_id();
 	struct pt_regs *old_regs = set_irq_regs(regs);

 	if (ipinr < NR_IPI)
 		__inc_irq_stat(cpu, ipi_irqs[ipinr]);

 	switch (ipinr) {
 	case IPI_WAKEUP:
 		break;

 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 	case IPI_TIMER:
 		irq_enter();
 		tick_receive_broadcast();
 		irq_exit();
 		break;
 #endif

 	case IPI_RESCHEDULE:
 		scheduler_ipi();
 		break;

 	case IPI_CALL_FUNC:
 		irq_enter();
 		generic_smp_call_function_interrupt();
 		irq_exit();
 		break;

 	case IPI_CALL_FUNC_SINGLE:
 		irq_enter();
 		generic_smp_call_function_single_interrupt();
 		irq_exit();
 		break;

 	case IPI_CPU_STOP:
 		irq_enter();
 		ipi_cpu_stop(cpu);
 		irq_exit();
 		break;

 #ifdef CONFIG_IRQ_WORK
 	case IPI_IRQ_WORK:
 		irq_enter();
 		irq_work_run();
 		irq_exit();
 		break;
 #endif

 	case IPI_COMPLETION:
 		irq_enter();
 		ipi_complete(cpu);
 		irq_exit();
 		break;

 	default:
 		printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
 		       cpu, ipinr);
 		break;
 	}
 	set_irq_regs(old_regs);
 }

 void smp_send_reschedule(int cpu)
 {
 	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 }

 void smp_send_stop(void)
 {
 	unsigned long timeout;
 	struct cpumask mask;

 	cpumask_copy(&mask, cpu_online_mask);
 	cpumask_clear_cpu(smp_processor_id(), &mask);
 	if (!cpumask_empty(&mask))
 		smp_cross_call(&mask, IPI_CPU_STOP);

 	/* Wait up to one second for other CPUs to stop */
 	timeout = USEC_PER_SEC;
 	while (num_online_cpus() > 1 && timeout--)
 		udelay(1);

 	if (num_online_cpus() > 1)
 		pr_warning("SMP: failed to stop secondary CPUs\n");
 }

 /*
  * not supported here
  */
 int setup_profiling_timer(unsigned int multiplier)
 {
 	return -EINVAL;
 }

 #ifdef CONFIG_CPU_FREQ

 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 static unsigned long global_l_p_j_ref;
 static unsigned long global_l_p_j_ref_freq;

 static int cpufreq_callback(struct notifier_block *nb,
 					unsigned long val, void *data)
 {
 	struct cpufreq_freqs *freq = data;
 	int cpu = freq->cpu;

 	if (freq->flags & CPUFREQ_CONST_LOOPS)
 		return NOTIFY_OK;

 	if (!per_cpu(l_p_j_ref, cpu)) {
 		per_cpu(l_p_j_ref, cpu) =
 			per_cpu(cpu_data, cpu).loops_per_jiffy;
 		per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 		if (!global_l_p_j_ref) {
 			global_l_p_j_ref = loops_per_jiffy;
 			global_l_p_j_ref_freq = freq->old;
 		}
 	}

 	if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 	    (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
 	    (val == CPUFREQ_RESUMECHANGE || val == CPUFREQ_SUSPENDCHANGE)) {
 		loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 						global_l_p_j_ref_freq,
 						freq->new);
 		per_cpu(cpu_data, cpu).loops_per_jiffy =
 			cpufreq_scale(per_cpu(l_p_j_ref, cpu),
 					per_cpu(l_p_j_ref_freq, cpu),
 					freq->new);
 	}
 	return NOTIFY_OK;
 }

 static struct notifier_block cpufreq_notifier = {
 	.notifier_call  = cpufreq_callback,
 };

 static int __init register_cpufreq_notifier(void)
 {
 	return cpufreq_register_notifier(&cpufreq_notifier,
 						CPUFREQ_TRANSITION_NOTIFIER);
 }
 core_initcall(register_cpufreq_notifier);

 #endif
	/*
	* linux/arch/arm/kernel/smp.c
	*
	* Copyright (C) 2002 ARM Limited, All Rights Reserved.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/
	#include <linux/module.h>
	#include <linux/delay.h>
	#include <linux/init.h>
	#include <linux/spinlock.h>
	#include <linux/sched.h>
	#include <linux/interrupt.h>
	#include <linux/cache.h>
	#include <linux/profile.h>
	#include <linux/errno.h>
	#include <linux/mm.h>
	#include <linux/err.h>
	#include <linux/cpu.h>
	#include <linux/seq_file.h>
	#include <linux/irq.h>
	#include <linux/percpu.h>
	#include <linux/clockchips.h>
	#include <linux/completion.h>
	#include <linux/cpufreq.h>
	#include <linux/irq_work.h>

	#include <linux/atomic.h>
	#include <asm/smp.h>
	#include <asm/cacheflush.h>
	#include <asm/cpu.h>
	#include <asm/cputype.h>
	#include <asm/exception.h>
	#include <asm/idmap.h>
	#include <asm/topology.h>
	#include <asm/mmu_context.h>
	#include <asm/pgtable.h>
	#include <asm/pgalloc.h>
	#include <asm/processor.h>
	#include <asm/sections.h>
	#include <asm/tlbflush.h>
	#include <asm/ptrace.h>
	#include <asm/smp_plat.h>
	#include <asm/virt.h>
	#include <asm/mach/arch.h>
	#include <asm/mpu.h>

	/*
	* as from 2.5, kernels no longer have an init_tasks structure
	* so we need some other way of telling a new secondary core
	* where to place its SVC stack
	*/
	struct secondary_data secondary_data;

	/*
	* control for which core is the next to come out of the secondary
	* boot "holding pen"
	*/
	volatile int pen_release = -1;

	enum ipi_msg_type {
	IPI_WAKEUP,
	IPI_TIMER,
	IPI_RESCHEDULE,
	IPI_CALL_FUNC,
	IPI_CALL_FUNC_SINGLE,
	IPI_CPU_STOP,
	IPI_IRQ_WORK,
	IPI_COMPLETION,
	};

	static DECLARE_COMPLETION(cpu_running);

	static struct smp_operations smp_ops;

	void __init smp_set_ops(struct smp_operations *ops)
	{
	if (ops)
	smp_ops = *ops;
	};

	static unsigned long get_arch_pgd(pgd_t *pgd)
	{
	phys_addr_t pgdir = virt_to_idmap(pgd);
	BUG_ON(pgdir & ARCH_PGD_MASK);
	return pgdir >> ARCH_PGD_SHIFT;
	}

	int __cpu_up(unsigned int cpu, struct task_struct *idle)
	{
	int ret;

	/*
	* We need to tell the secondary core where to find
	* its stack and the page tables.
	*/
	secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
	#ifdef CONFIG_ARM_MPU
	secondary_data.mpu_rgn_szr = mpu_rgn_info.rgns[MPU_RAM_REGION].drsr;
	#endif

	#ifdef CONFIG_MMU
	secondary_data.pgdir = get_arch_pgd(idmap_pgd);
	secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
	#endif
	sync_cache_w(&secondary_data);

	/*
	* Now bring the CPU into our world.
	*/
	ret = boot_secondary(cpu, idle);
	if (ret == 0) {
	/*
	* CPU was successfully started, wait for it
	* to come online or time out.
	*/
	wait_for_completion_timeout(&cpu_running,
	msecs_to_jiffies(1000));

	if (!cpu_online(cpu)) {
	pr_crit("CPU%u: failed to come online\n", cpu);
	ret = -EIO;
	}
	} else {
	pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
	}


	memset(&secondary_data, 0, sizeof(secondary_data));
	return ret;
	}

	/* platform specific SMP operations */
	void __init smp_init_cpus(void)
	{
	if (smp_ops.smp_init_cpus)
	smp_ops.smp_init_cpus();
	}

	int boot_secondary(unsigned int cpu, struct task_struct *idle)
	{
	if (smp_ops.smp_boot_secondary)
	return smp_ops.smp_boot_secondary(cpu, idle);
	return -ENOSYS;
	}

	int platform_can_cpu_hotplug(void)
	{
	#ifdef CONFIG_HOTPLUG_CPU
	if (smp_ops.cpu_kill)
	return 1;
	#endif

	return 0;
	}

	#ifdef CONFIG_HOTPLUG_CPU
	static int platform_cpu_kill(unsigned int cpu)
	{
	if (smp_ops.cpu_kill)
	return smp_ops.cpu_kill(cpu);
	return 1;
	}

	static int platform_cpu_disable(unsigned int cpu)
	{
	if (smp_ops.cpu_disable)
	return smp_ops.cpu_disable(cpu);

	/*
	* By default, allow disabling all CPUs except the first one,
	* since this is special on a lot of platforms, e.g. because
	* of clock tick interrupts.
	*/
	return cpu == 0 ? -EPERM : 0;
	}
	/*
	* __cpu_disable runs on the processor to be shutdown.
	*/
	int __cpu_disable(void)
	{
	unsigned int cpu = smp_processor_id();
	int ret;

	ret = platform_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.
	*/
	set_cpu_online(cpu, false);

	/*
	* OK - migrate IRQs away from this CPU
	*/
	migrate_irqs();

	/*
	* Flush user cache and TLB mappings, and then remove this CPU
	* from the vm mask set of all processes.
	*
	* Caches are flushed to the Level of Unification Inner Shareable
	* to write-back dirty lines to unified caches shared by all CPUs.
	*/
	flush_cache_louis();
	local_flush_tlb_all();

	clear_tasks_mm_cpumask(cpu);

	return 0;
	}

	static DECLARE_COMPLETION(cpu_died);

	/*
	* called on the thread which is asking for a CPU to be shutdown -
	* waits until shutdown has completed, or it is timed out.
	*/
	void __cpu_die(unsigned int cpu)
	{
	if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
	pr_err("CPU%u: cpu didn't die\n", cpu);
	return;
	}
	printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);

	/*
	* platform_cpu_kill() is generally expected to do the powering off
	* and/or cutting of clocks to the dying CPU. Optionally, this may
	* be done by the CPU which is dying in preference to supporting
	* this call, but that means there is _no_ synchronisation between
	* the requesting CPU and the dying CPU actually losing power.
	*/
	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 __ref cpu_die(void)
	{
	unsigned int cpu = smp_processor_id();

	idle_task_exit();

	local_irq_disable();

	/*
	* Flush the data out of the L1 cache for this CPU. This must be
	* before the completion to ensure that data is safely written out
	* before platform_cpu_kill() gets called - which may disable
	* this CPU and power down its cache.
	*/
	flush_cache_louis();

	/*
	* Tell __cpu_die() that this CPU is now safe to dispose of. Once
	* this returns, power and/or clocks can be removed at any point
	* from this CPU and its cache by platform_cpu_kill().
	*/
	complete(&cpu_died);

	/*
	* Ensure that the cache lines associated with that completion are
	* written out. This covers the case where _this_ CPU is doing the
	* powering down, to ensure that the completion is visible to the
	* CPU waiting for this one.
	*/
	flush_cache_louis();

	/*
	* The actual CPU shutdown procedure is at least platform (if not
	* CPU) specific. This may remove power, or it may simply spin.
	*
	* Platforms are generally expected NOT to return from this call,
	* although there are some which do because they have no way to
	* power down the CPU. These platforms are the _only_ reason we
	* have a return path which uses the fragment of assembly below.
	*
	* The return path should not be used for platforms which can
	* power off the CPU.
	*/
	if (smp_ops.cpu_die)
	smp_ops.cpu_die(cpu);

	pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
	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"
	" mov fp, #0\n"
	" b secondary_start_kernel"
	:
	: "r" (task_stack_page(current) + THREAD_SIZE - 8));
	}
	#endif /* CONFIG_HOTPLUG_CPU */

	/*
	* Called by both boot and secondaries to move global data into
	* per-processor storage.
	*/
	static void smp_store_cpu_info(unsigned int cpuid)
	{
	struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);

	cpu_info->loops_per_jiffy = loops_per_jiffy;
	cpu_info->cpuid = read_cpuid_id();

	store_cpu_topology(cpuid);
	}

	/*
	* This is the secondary CPU boot entry. We're using this CPUs
	* idle thread stack, but a set of temporary page tables.
	*/
	asmlinkage void secondary_start_kernel(void)
	{
	struct mm_struct *mm = &init_mm;
	unsigned int cpu;

	/*
	* The identity mapping is uncached (strongly ordered), so
	* switch away from it before attempting any exclusive accesses.
	*/
	cpu_switch_mm(mm->pgd, mm);
	local_flush_bp_all();
	enter_lazy_tlb(mm, current);
	local_flush_tlb_all();

	/*
	* All kernel threads share the same mm context; grab a
	* reference and switch to it.
	*/
	cpu = smp_processor_id();
	atomic_inc(&mm->mm_count);
	current->active_mm = mm;
	cpumask_set_cpu(cpu, mm_cpumask(mm));

	cpu_init();

	printk("CPU%u: Booted secondary processor\n", cpu);

	preempt_disable();
	trace_hardirqs_off();

	/*
	* Give the platform a chance to do its own initialisation.
	*/
	if (smp_ops.smp_secondary_init)
	smp_ops.smp_secondary_init(cpu);

	notify_cpu_starting(cpu);

	calibrate_delay();

	smp_store_cpu_info(cpu);

	/*
	* OK, now it's safe to let the boot CPU continue. Wait for
	* the CPU migration code to notice that the CPU is online
	* before we continue - which happens after __cpu_up returns.
	*/
	set_cpu_online(cpu, true);
	complete(&cpu_running);

	local_irq_enable();
	local_fiq_enable();

	/*
	* OK, it's off to the idle thread for us
	*/
	cpu_startup_entry(CPUHP_ONLINE);
	}

	void __init smp_cpus_done(unsigned int max_cpus)
	{
	printk(KERN_INFO "SMP: Total of %d processors activated.\n",
	num_online_cpus());

	hyp_mode_check();
	}

	void __init smp_prepare_boot_cpu(void)
	{
	set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
	}

	void __init smp_prepare_cpus(unsigned int max_cpus)
	{
	unsigned int ncores = num_possible_cpus();

	init_cpu_topology();

	smp_store_cpu_info(smp_processor_id());

	/*
	* are we trying to boot more cores than exist?
	*/
	if (max_cpus > ncores)
	max_cpus = ncores;
	if (ncores > 1 && max_cpus) {
	/*
	* Initialise the present map, which describes the set of CPUs
	* actually populated at the present time. A platform should
	* re-initialize the map in the platforms smp_prepare_cpus()
	* if present != possible (e.g. physical hotplug).
	*/
	init_cpu_present(cpu_possible_mask);

	/*
	* Initialise the SCU if there are more than one CPU
	* and let them know where to start.
	*/
	if (smp_ops.smp_prepare_cpus)
	smp_ops.smp_prepare_cpus(max_cpus);
	}
	}

	static void (smp_cross_call)(const struct cpumask , unsigned int);

	void __init set_smp_cross_call(void (fn)(const struct cpumask , unsigned int))
	{
	if (!smp_cross_call)
	smp_cross_call = fn;
	}

	void arch_send_call_function_ipi_mask(const struct cpumask *mask)
	{
	smp_cross_call(mask, IPI_CALL_FUNC);
	}

	void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
	{
	smp_cross_call(mask, IPI_WAKEUP);
	}

	void arch_send_call_function_single_ipi(int cpu)
	{
	smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
	}

	#ifdef CONFIG_IRQ_WORK
	void arch_irq_work_raise(void)
	{
	if (is_smp())
	smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
	}
	#endif

	static const char *ipi_types[NR_IPI] = {
	#define S(x,s) [x] = s
	S(IPI_WAKEUP, "CPU wakeup interrupts"),
	S(IPI_TIMER, "Timer broadcast interrupts"),
	S(IPI_RESCHEDULE, "Rescheduling interrupts"),
	S(IPI_CALL_FUNC, "Function call interrupts"),
	S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
	S(IPI_CPU_STOP, "CPU stop interrupts"),
	S(IPI_IRQ_WORK, "IRQ work interrupts"),
	S(IPI_COMPLETION, "completion interrupts"),
	};

	void show_ipi_list(struct seq_file *p, int prec)
	{
	unsigned int cpu, i;

	for (i = 0; i < NR_IPI; i++) {
	seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);

	for_each_online_cpu(cpu)
	seq_printf(p, "%10u ",
	__get_irq_stat(cpu, ipi_irqs[i]));

	seq_printf(p, " %s\n", ipi_types[i]);
	}
	}

	u64 smp_irq_stat_cpu(unsigned int cpu)
	{
	u64 sum = 0;
	int i;

	for (i = 0; i < NR_IPI; i++)
	sum += __get_irq_stat(cpu, ipi_irqs[i]);

	return sum;
	}

	#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
	void tick_broadcast(const struct cpumask *mask)
	{
	smp_cross_call(mask, IPI_TIMER);
	}
	#endif

	static DEFINE_RAW_SPINLOCK(stop_lock);

	/*
	* ipi_cpu_stop - handle IPI from smp_send_stop()
	*/
	static void ipi_cpu_stop(unsigned int cpu)
	{
	if (system_state == SYSTEM_BOOTING \|\|
	system_state == SYSTEM_RUNNING) {
	raw_spin_lock(&stop_lock);
	printk(KERN_CRIT "CPU%u: stopping\n", cpu);
	dump_stack();
	raw_spin_unlock(&stop_lock);
	}

	set_cpu_online(cpu, false);

	local_fiq_disable();
	local_irq_disable();

	while (1)
	cpu_relax();
	}

	static DEFINE_PER_CPU(struct completion *, cpu_completion);

	int register_ipi_completion(struct completion *completion, int cpu)
	{
	per_cpu(cpu_completion, cpu) = completion;
	return IPI_COMPLETION;
	}

	static void ipi_complete(unsigned int cpu)
	{
	complete(per_cpu(cpu_completion, cpu));
	}

	/*
	* Main handler for inter-processor interrupts
	*/
	asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
	{
	handle_IPI(ipinr, regs);
	}

	void handle_IPI(int ipinr, struct pt_regs *regs)
	{
	unsigned int cpu = smp_processor_id();
	struct pt_regs *old_regs = set_irq_regs(regs);

	if (ipinr < NR_IPI)
	__inc_irq_stat(cpu, ipi_irqs[ipinr]);

	switch (ipinr) {
	case IPI_WAKEUP:
	break;

	#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
	case IPI_TIMER:
	irq_enter();
	tick_receive_broadcast();
	irq_exit();
	break;
	#endif

	case IPI_RESCHEDULE:
	scheduler_ipi();
	break;

	case IPI_CALL_FUNC:
	irq_enter();
	generic_smp_call_function_interrupt();
	irq_exit();
	break;

	case IPI_CALL_FUNC_SINGLE:
	irq_enter();
	generic_smp_call_function_single_interrupt();
	irq_exit();
	break;

	case IPI_CPU_STOP:
	irq_enter();
	ipi_cpu_stop(cpu);
	irq_exit();
	break;

	#ifdef CONFIG_IRQ_WORK
	case IPI_IRQ_WORK:
	irq_enter();
	irq_work_run();
	irq_exit();
	break;
	#endif

	case IPI_COMPLETION:
	irq_enter();
	ipi_complete(cpu);
	irq_exit();
	break;

	default:
	printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
	cpu, ipinr);
	break;
	}
	set_irq_regs(old_regs);
	}

	void smp_send_reschedule(int cpu)
	{
	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
	}

	void smp_send_stop(void)
	{
	unsigned long timeout;
	struct cpumask mask;

	cpumask_copy(&mask, cpu_online_mask);
	cpumask_clear_cpu(smp_processor_id(), &mask);
	if (!cpumask_empty(&mask))
	smp_cross_call(&mask, IPI_CPU_STOP);

	/* Wait up to one second for other CPUs to stop */
	timeout = USEC_PER_SEC;
	while (num_online_cpus() > 1 && timeout--)
	udelay(1);

	if (num_online_cpus() > 1)
	pr_warning("SMP: failed to stop secondary CPUs\n");
	}

	/*
	* not supported here
	*/
	int setup_profiling_timer(unsigned int multiplier)
	{
	return -EINVAL;
	}

	#ifdef CONFIG_CPU_FREQ

	static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
	static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
	static unsigned long global_l_p_j_ref;
	static unsigned long global_l_p_j_ref_freq;

	static int cpufreq_callback(struct notifier_block *nb,
	unsigned long val, void *data)
	{
	struct cpufreq_freqs *freq = data;
	int cpu = freq->cpu;

	if (freq->flags & CPUFREQ_CONST_LOOPS)
	return NOTIFY_OK;

	if (!per_cpu(l_p_j_ref, cpu)) {
	per_cpu(l_p_j_ref, cpu) =
	per_cpu(cpu_data, cpu).loops_per_jiffy;
	per_cpu(l_p_j_ref_freq, cpu) = freq->old;
	if (!global_l_p_j_ref) {
	global_l_p_j_ref = loops_per_jiffy;
	global_l_p_j_ref_freq = freq->old;
	}
	}

	if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) \|\|
	(val == CPUFREQ_POSTCHANGE && freq->old > freq->new) \|\|
	(val == CPUFREQ_RESUMECHANGE \|\| val == CPUFREQ_SUSPENDCHANGE)) {
	loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
	global_l_p_j_ref_freq,
	freq->new);
	per_cpu(cpu_data, cpu).loops_per_jiffy =
	cpufreq_scale(per_cpu(l_p_j_ref, cpu),
	per_cpu(l_p_j_ref_freq, cpu),
	freq->new);
	}
	return NOTIFY_OK;
	}

	static struct notifier_block cpufreq_notifier = {
	.notifier_call = cpufreq_callback,
	};

	static int __init register_cpufreq_notifier(void)
	{
	return cpufreq_register_notifier(&cpufreq_notifier,
	CPUFREQ_TRANSITION_NOTIFIER);
	}
	core_initcall(register_cpufreq_notifier);

	#endif