smp.c

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/*
 *  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/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/localtimer.h>
#include <asm/smp_plat.h>
#include <asm/virt.h>
#include <asm/mach/arch.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 __cpuinitdata pen_release = -1;

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

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;
};

int __cpuinit __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;
    secondary_data.pgdir = virt_to_phys(idmap_pgd);
    secondary_data.swapper_pg_dir = virt_to_phys(swapper_pg_dir);
    __cpuc_flush_dcache_area(&secondary_data, sizeof(secondary_data));
    outer_clean_range(__pa(&secondary_data), __pa(&secondary_data + 1));

    /*
     * 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);
    }

    secondary_data.stack = NULL;
    secondary_data.pgdir = 0;

    return ret;
}

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

static void __init platform_smp_prepare_cpus(unsigned int max_cpus)
{
    if (smp_ops.smp_prepare_cpus)
        smp_ops.smp_prepare_cpus(max_cpus);
}

static void __cpuinit platform_secondary_init(unsigned int cpu)
{
    if (smp_ops.smp_secondary_init)
        smp_ops.smp_secondary_init(cpu);
}

int __cpuinit 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;
}

#ifdef CONFIG_HOTPLUG_CPU
static void percpu_timer_stop(void);

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

static void platform_cpu_die(unsigned int cpu)
{
    if (smp_ops.cpu_die)
        smp_ops.cpu_die(cpu);
}

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 __cpuinit __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();

    /*
     * Stop the local timer for this CPU.
     */
    percpu_timer_stop();

    /*
     * 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 __cpuinit __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);

    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();
    mb();

    /* Tell __cpu_die() that this CPU is now safe to dispose of */
    RCU_NONIDLE(complete(&cpu_died));

    /*
     * 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"
    "   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 __cpuinit 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;

    store_cpu_topology(cpuid);
}

static void percpu_timer_setup(void);

/*
 * 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;

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

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

    cpu_init();
    preempt_disable();
    trace_hardirqs_off();

    /*
     * Give the platform a chance to do its own initialisation.
     */
    platform_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);

    /*
     * Setup the percpu timer for this CPU.
     */
    percpu_timer_setup();

    local_irq_enable();
    local_fiq_enable();

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

void __init smp_cpus_done(unsigned int max_cpus)
{
    int cpu;
    unsigned long bogosum = 0;

    for_each_online_cpu(cpu)
        bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;

    printk(KERN_INFO "SMP: Total of %d processors activated "
           "(%lu.%02lu BogoMIPS).\n",
           num_online_cpus(),
           bogosum / (500000/HZ),
           (bogosum / (5000/HZ)) % 100);

    hyp_mode_check();
}

void __init smp_prepare_boot_cpu(void)
{
}

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) {
        /*
         * Enable the local timer or broadcast device for the
         * boot CPU, but only if we have more than one CPU.
         */
        percpu_timer_setup();

        /*
         * Initialise the present map, which describes the set of CPUs
         * actually populated at the present time. A platform should
         * re-initialize the map in platform_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.
         */
        platform_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))
{
    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_call_function_single_ipi(int cpu)
{
    smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
}

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"),
};

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_present_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;
}

/*
 * Timer (local or broadcast) support
 */
static DEFINE_PER_CPU(struct clock_event_device, percpu_clockevent);

static void ipi_timer(void)
{
    struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent);
    evt->event_handler(evt);
}

#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
static void smp_timer_broadcast(const struct cpumask *mask)
{
    smp_cross_call(mask, IPI_TIMER);
}
#else
#define smp_timer_broadcast NULL
#endif

static void broadcast_timer_set_mode(enum clock_event_mode mode,
    struct clock_event_device *evt)
{
}

static void __cpuinit broadcast_timer_setup(struct clock_event_device *evt)
{
    evt->name   = "dummy_timer";
    evt->features   = CLOCK_EVT_FEAT_ONESHOT |
              CLOCK_EVT_FEAT_PERIODIC |
              CLOCK_EVT_FEAT_DUMMY;
    evt->rating = 400;
    evt->mult   = 1;
    evt->set_mode   = broadcast_timer_set_mode;

    clockevents_register_device(evt);
}

static struct local_timer_ops *lt_ops;

#ifdef CONFIG_LOCAL_TIMERS
int local_timer_register(struct local_timer_ops *ops)
{
    if (!is_smp() || !setup_max_cpus)
        return -ENXIO;

    if (lt_ops)
        return -EBUSY;

    lt_ops = ops;
    return 0;
}
#endif

static void __cpuinit percpu_timer_setup(void)
{
    unsigned int cpu = smp_processor_id();
    struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);

    evt->cpumask = cpumask_of(cpu);
    evt->broadcast = smp_timer_broadcast;

    if (!lt_ops || lt_ops->setup(evt))
        broadcast_timer_setup(evt);
}

#ifdef CONFIG_HOTPLUG_CPU
/*
 * The generic clock events code purposely does not stop the local timer
 * on CPU_DEAD/CPU_DEAD_FROZEN hotplug events, so we have to do it
 * manually here.
 */
static void percpu_timer_stop(void)
{
    unsigned int cpu = smp_processor_id();
    struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);

    if (lt_ops)
        lt_ops->stop(evt);
}
#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();
}

/*
 * 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;

    case IPI_TIMER:
        irq_enter();
        ipi_timer();
        irq_exit();
        break;

    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;

    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);
}

#ifdef CONFIG_HOTPLUG_CPU
static void smp_kill_cpus(cpumask_t *mask)
{
    unsigned int cpu;
    for_each_cpu(cpu, mask)
        platform_cpu_kill(cpu);
}
#else
static void smp_kill_cpus(cpumask_t *mask) { }
#endif

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");

    smp_kill_cpus(&mask);
}

/*
 * 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