smp.c

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/*
 * SMP support for ppc.
 *
 * Written by Cort Dougan ([email protected]) borrowing a great
 * deal of code from the sparc and intel versions.
 *
 * Copyright (C) 1999 Cort Dougan <[email protected]>
 *
 * PowerPC-64 Support added by Dave Engebretsen, Peter Bergner, and
 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/cache.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/topology.h>

#include <asm/ptrace.h>
#include <linux/atomic.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/time.h>
#include <asm/machdep.h>
#include <asm/cputhreads.h>
#include <asm/cputable.h>
#include <asm/mpic.h>
#include <asm/vdso_datapage.h>
#ifdef CONFIG_PPC64
#include <asm/paca.h>
#endif
#include <asm/vdso.h>
#include <asm/debug.h>

#ifdef DEBUG
#include <asm/udbg.h>
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif

#ifdef CONFIG_HOTPLUG_CPU
/* State of each CPU during hotplug phases */
static DEFINE_PER_CPU(int, cpu_state) = { 0 };
#endif

struct thread_info *secondary_ti;

DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
DEFINE_PER_CPU(cpumask_var_t, cpu_core_map);

EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
EXPORT_PER_CPU_SYMBOL(cpu_core_map);

/* SMP operations for this machine */
struct smp_ops_t *smp_ops;

/* Can't be static due to PowerMac hackery */
volatile unsigned int cpu_callin_map[NR_CPUS];

int smt_enabled_at_boot = 1;

static void (*crash_ipi_function_ptr)(struct pt_regs *) = NULL;

#ifdef CONFIG_PPC64
int __devinit smp_generic_kick_cpu(int nr)
{
    BUG_ON(nr < 0 || nr >= NR_CPUS);

    /*
     * The processor is currently spinning, waiting for the
     * cpu_start field to become non-zero After we set cpu_start,
     * the processor will continue on to secondary_start
     */
    if (!paca[nr].cpu_start) {
        paca[nr].cpu_start = 1;
        smp_mb();
        return 0;
    }

#ifdef CONFIG_HOTPLUG_CPU
    /*
     * Ok it's not there, so it might be soft-unplugged, let's
     * try to bring it back
     */
    generic_set_cpu_up(nr);
    smp_wmb();
    smp_send_reschedule(nr);
#endif /* CONFIG_HOTPLUG_CPU */

    return 0;
}
#endif /* CONFIG_PPC64 */

static irqreturn_t call_function_action(int irq, void *data)
{
    generic_smp_call_function_interrupt();
    return IRQ_HANDLED;
}

static irqreturn_t reschedule_action(int irq, void *data)
{
    scheduler_ipi();
    return IRQ_HANDLED;
}

static irqreturn_t call_function_single_action(int irq, void *data)
{
    generic_smp_call_function_single_interrupt();
    return IRQ_HANDLED;
}

static irqreturn_t debug_ipi_action(int irq, void *data)
{
    if (crash_ipi_function_ptr) {
        crash_ipi_function_ptr(get_irq_regs());
        return IRQ_HANDLED;
    }

#ifdef CONFIG_DEBUGGER
    debugger_ipi(get_irq_regs());
#endif /* CONFIG_DEBUGGER */

    return IRQ_HANDLED;
}

static irq_handler_t smp_ipi_action[] = {
    [PPC_MSG_CALL_FUNCTION] =  call_function_action,
    [PPC_MSG_RESCHEDULE] = reschedule_action,
    [PPC_MSG_CALL_FUNC_SINGLE] = call_function_single_action,
    [PPC_MSG_DEBUGGER_BREAK] = debug_ipi_action,
};

const char *smp_ipi_name[] = {
    [PPC_MSG_CALL_FUNCTION] =  "ipi call function",
    [PPC_MSG_RESCHEDULE] = "ipi reschedule",
    [PPC_MSG_CALL_FUNC_SINGLE] = "ipi call function single",
    [PPC_MSG_DEBUGGER_BREAK] = "ipi debugger",
};

/* optional function to request ipi, for controllers with >= 4 ipis */
int smp_request_message_ipi(int virq, int msg)
{
    int err;

    if (msg < 0 || msg > PPC_MSG_DEBUGGER_BREAK) {
        return -EINVAL;
    }
#if !defined(CONFIG_DEBUGGER) && !defined(CONFIG_KEXEC)
    if (msg == PPC_MSG_DEBUGGER_BREAK) {
        return 1;
    }
#endif
    err = request_irq(virq, smp_ipi_action[msg],
              IRQF_PERCPU | IRQF_NO_THREAD | IRQF_NO_SUSPEND,
              smp_ipi_name[msg], 0);
    WARN(err < 0, "unable to request_irq %d for %s (rc %d)\n",
        virq, smp_ipi_name[msg], err);

    return err;
}

#ifdef CONFIG_PPC_SMP_MUXED_IPI
struct cpu_messages {
    int messages;           /* current messages */
    unsigned long data;     /* data for cause ipi */
};
static DEFINE_PER_CPU_SHARED_ALIGNED(struct cpu_messages, ipi_message);

void smp_muxed_ipi_set_data(int cpu, unsigned long data)
{
    struct cpu_messages *info = &per_cpu(ipi_message, cpu);

    info->data = data;
}

void smp_muxed_ipi_message_pass(int cpu, int msg)
{
    struct cpu_messages *info = &per_cpu(ipi_message, cpu);
    char *message = (char *)&info->messages;

    /*
     * Order previous accesses before accesses in the IPI handler.
     */
    smp_mb();
    message[msg] = 1;
    /*
     * cause_ipi functions are required to include a full barrier
     * before doing whatever causes the IPI.
     */
    smp_ops->cause_ipi(cpu, info->data);
}

irqreturn_t smp_ipi_demux(void)
{
    struct cpu_messages *info = &__get_cpu_var(ipi_message);
    unsigned int all;

    mb();   /* order any irq clear */

    do {
        all = xchg(&info->messages, 0);

#ifdef __BIG_ENDIAN
        if (all & (1 << (24 - 8 * PPC_MSG_CALL_FUNCTION)))
            generic_smp_call_function_interrupt();
        if (all & (1 << (24 - 8 * PPC_MSG_RESCHEDULE)))
            scheduler_ipi();
        if (all & (1 << (24 - 8 * PPC_MSG_CALL_FUNC_SINGLE)))
            generic_smp_call_function_single_interrupt();
        if (all & (1 << (24 - 8 * PPC_MSG_DEBUGGER_BREAK)))
            debug_ipi_action(0, NULL);
#else
#error Unsupported ENDIAN
#endif
    } while (info->messages);

    return IRQ_HANDLED;
}
#endif /* CONFIG_PPC_SMP_MUXED_IPI */

static inline void do_message_pass(int cpu, int msg)
{
    if (smp_ops->message_pass)
        smp_ops->message_pass(cpu, msg);
#ifdef CONFIG_PPC_SMP_MUXED_IPI
    else
        smp_muxed_ipi_message_pass(cpu, msg);
#endif
}

void smp_send_reschedule(int cpu)
{
    if (likely(smp_ops))
        do_message_pass(cpu, PPC_MSG_RESCHEDULE);
}
EXPORT_SYMBOL_GPL(smp_send_reschedule);

void arch_send_call_function_single_ipi(int cpu)
{
    do_message_pass(cpu, PPC_MSG_CALL_FUNC_SINGLE);
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
    unsigned int cpu;

    for_each_cpu(cpu, mask)
        do_message_pass(cpu, PPC_MSG_CALL_FUNCTION);
}

#if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
void smp_send_debugger_break(void)
{
    int cpu;
    int me = raw_smp_processor_id();

    if (unlikely(!smp_ops))
        return;

    for_each_online_cpu(cpu)
        if (cpu != me)
            do_message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
}
#endif

#ifdef CONFIG_KEXEC
void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *))
{
    crash_ipi_function_ptr = crash_ipi_callback;
    if (crash_ipi_callback) {
        mb();
        smp_send_debugger_break();
    }
}
#endif

static void stop_this_cpu(void *dummy)
{
    /* Remove this CPU */
    set_cpu_online(smp_processor_id(), false);

    local_irq_disable();
    while (1)
        ;
}

void smp_send_stop(void)
{
    smp_call_function(stop_this_cpu, NULL, 0);
}

struct thread_info *current_set[NR_CPUS];

static void __devinit smp_store_cpu_info(int id)
{
    per_cpu(cpu_pvr, id) = mfspr(SPRN_PVR);
#ifdef CONFIG_PPC_FSL_BOOK3E
    per_cpu(next_tlbcam_idx, id)
        = (mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY) - 1;
#endif
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
    unsigned int cpu;

    DBG("smp_prepare_cpus\n");

    /* 
     * setup_cpu may need to be called on the boot cpu. We havent
     * spun any cpus up but lets be paranoid.
     */
    BUG_ON(boot_cpuid != smp_processor_id());

    /* Fixup boot cpu */
    smp_store_cpu_info(boot_cpuid);
    cpu_callin_map[boot_cpuid] = 1;

    for_each_possible_cpu(cpu) {
        zalloc_cpumask_var_node(&per_cpu(cpu_sibling_map, cpu),
                    GFP_KERNEL, cpu_to_node(cpu));
        zalloc_cpumask_var_node(&per_cpu(cpu_core_map, cpu),
                    GFP_KERNEL, cpu_to_node(cpu));
    }

    cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid));
    cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid));

    if (smp_ops)
        if (smp_ops->probe)
            max_cpus = smp_ops->probe();
        else
            max_cpus = NR_CPUS;
    else
        max_cpus = 1;
}

void __devinit smp_prepare_boot_cpu(void)
{
    BUG_ON(smp_processor_id() != boot_cpuid);
#ifdef CONFIG_PPC64
    paca[boot_cpuid].__current = current;
#endif
    current_set[boot_cpuid] = task_thread_info(current);
}

#ifdef CONFIG_HOTPLUG_CPU

int generic_cpu_disable(void)
{
    unsigned int cpu = smp_processor_id();

    if (cpu == boot_cpuid)
        return -EBUSY;

    set_cpu_online(cpu, false);
#ifdef CONFIG_PPC64
    vdso_data->processorCount--;
#endif
    migrate_irqs();
    return 0;
}

void generic_cpu_die(unsigned int cpu)
{
    int i;

    for (i = 0; i < 100; i++) {
        smp_rmb();
        if (per_cpu(cpu_state, cpu) == CPU_DEAD)
            return;
        msleep(100);
    }
    printk(KERN_ERR "CPU%d didn't die...\n", cpu);
}

void generic_mach_cpu_die(void)
{
    unsigned int cpu;

    local_irq_disable();
    idle_task_exit();
    cpu = smp_processor_id();
    printk(KERN_DEBUG "CPU%d offline\n", cpu);
    __get_cpu_var(cpu_state) = CPU_DEAD;
    smp_wmb();
    while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
        cpu_relax();
}

void generic_set_cpu_dead(unsigned int cpu)
{
    per_cpu(cpu_state, cpu) = CPU_DEAD;
}

/*
 * The cpu_state should be set to CPU_UP_PREPARE in kick_cpu(), otherwise
 * the cpu_state is always CPU_DEAD after calling generic_set_cpu_dead(),
 * which makes the delay in generic_cpu_die() not happen.
 */
void generic_set_cpu_up(unsigned int cpu)
{
    per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
}

int generic_check_cpu_restart(unsigned int cpu)
{
    return per_cpu(cpu_state, cpu) == CPU_UP_PREPARE;
}
#endif

static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle)
{
    struct thread_info *ti = task_thread_info(idle);

#ifdef CONFIG_PPC64
    paca[cpu].__current = idle;
    paca[cpu].kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD;
#endif
    ti->cpu = cpu;
    secondary_ti = current_set[cpu] = ti;
}

int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
{
    int rc, c;

    if (smp_ops == NULL ||
        (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
        return -EINVAL;

    cpu_idle_thread_init(cpu, tidle);

    /* Make sure callin-map entry is 0 (can be leftover a CPU
     * hotplug
     */
    cpu_callin_map[cpu] = 0;

    /* The information for processor bringup must
     * be written out to main store before we release
     * the processor.
     */
    smp_mb();

    /* wake up cpus */
    DBG("smp: kicking cpu %d\n", cpu);
    rc = smp_ops->kick_cpu(cpu);
    if (rc) {
        pr_err("smp: failed starting cpu %d (rc %d)\n", cpu, rc);
        return rc;
    }

    /*
     * wait to see if the cpu made a callin (is actually up).
     * use this value that I found through experimentation.
     * -- Cort
     */
    if (system_state < SYSTEM_RUNNING)
        for (c = 50000; c && !cpu_callin_map[cpu]; c--)
            udelay(100);
#ifdef CONFIG_HOTPLUG_CPU
    else
        /*
         * CPUs can take much longer to come up in the
         * hotplug case.  Wait five seconds.
         */
        for (c = 5000; c && !cpu_callin_map[cpu]; c--)
            msleep(1);
#endif

    if (!cpu_callin_map[cpu]) {
        printk(KERN_ERR "Processor %u is stuck.\n", cpu);
        return -ENOENT;
    }

    DBG("Processor %u found.\n", cpu);

    if (smp_ops->give_timebase)
        smp_ops->give_timebase();

    /* Wait until cpu puts itself in the online map */
    while (!cpu_online(cpu))
        cpu_relax();

    return 0;
}

/* Return the value of the reg property corresponding to the given
 * logical cpu.
 */
int cpu_to_core_id(int cpu)
{
    struct device_node *np;
    const int *reg;
    int id = -1;

    np = of_get_cpu_node(cpu, NULL);
    if (!np)
        goto out;

    reg = of_get_property(np, "reg", NULL);
    if (!reg)
        goto out;

    id = *reg;
out:
    of_node_put(np);
    return id;
}

/* Helper routines for cpu to core mapping */
int cpu_core_index_of_thread(int cpu)
{
    return cpu >> threads_shift;
}
EXPORT_SYMBOL_GPL(cpu_core_index_of_thread);

int cpu_first_thread_of_core(int core)
{
    return core << threads_shift;
}
EXPORT_SYMBOL_GPL(cpu_first_thread_of_core);

/* Must be called when no change can occur to cpu_present_mask,
 * i.e. during cpu online or offline.
 */
static struct device_node *cpu_to_l2cache(int cpu)
{
    struct device_node *np;
    struct device_node *cache;

    if (!cpu_present(cpu))
        return NULL;

    np = of_get_cpu_node(cpu, NULL);
    if (np == NULL)
        return NULL;

    cache = of_find_next_cache_node(np);

    of_node_put(np);

    return cache;
}

/* Activate a secondary processor. */
void __devinit start_secondary(void *unused)
{
    unsigned int cpu = smp_processor_id();
    struct device_node *l2_cache;
    int i, base;

    atomic_inc(&init_mm.mm_count);
    current->active_mm = &init_mm;

    smp_store_cpu_info(cpu);
    set_dec(tb_ticks_per_jiffy);
    preempt_disable();
    cpu_callin_map[cpu] = 1;

    if (smp_ops->setup_cpu)
        smp_ops->setup_cpu(cpu);
    if (smp_ops->take_timebase)
        smp_ops->take_timebase();

    secondary_cpu_time_init();

#ifdef CONFIG_PPC64
    if (system_state == SYSTEM_RUNNING)
        vdso_data->processorCount++;

    vdso_getcpu_init();
#endif
    notify_cpu_starting(cpu);
    set_cpu_online(cpu, true);
    /* Update sibling maps */
    base = cpu_first_thread_sibling(cpu);
    for (i = 0; i < threads_per_core; i++) {
        if (cpu_is_offline(base + i))
            continue;
        cpumask_set_cpu(cpu, cpu_sibling_mask(base + i));
        cpumask_set_cpu(base + i, cpu_sibling_mask(cpu));

        /* cpu_core_map should be a superset of
         * cpu_sibling_map even if we don't have cache
         * information, so update the former here, too.
         */
        cpumask_set_cpu(cpu, cpu_core_mask(base + i));
        cpumask_set_cpu(base + i, cpu_core_mask(cpu));
    }
    l2_cache = cpu_to_l2cache(cpu);
    for_each_online_cpu(i) {
        struct device_node *np = cpu_to_l2cache(i);
        if (!np)
            continue;
        if (np == l2_cache) {
            cpumask_set_cpu(cpu, cpu_core_mask(i));
            cpumask_set_cpu(i, cpu_core_mask(cpu));
        }
        of_node_put(np);
    }
    of_node_put(l2_cache);

    local_irq_enable();

    cpu_idle();

    BUG();
}

int setup_profiling_timer(unsigned int multiplier)
{
    return 0;
}

void __init smp_cpus_done(unsigned int max_cpus)
{
    cpumask_var_t old_mask;

    /* We want the setup_cpu() here to be called from CPU 0, but our
     * init thread may have been "borrowed" by another CPU in the meantime
     * se we pin us down to CPU 0 for a short while
     */
    alloc_cpumask_var(&old_mask, GFP_NOWAIT);
    cpumask_copy(old_mask, tsk_cpus_allowed(current));
    set_cpus_allowed_ptr(current, cpumask_of(boot_cpuid));
    
    if (smp_ops && smp_ops->setup_cpu)
        smp_ops->setup_cpu(boot_cpuid);

    set_cpus_allowed_ptr(current, old_mask);

    free_cpumask_var(old_mask);

    if (smp_ops && smp_ops->bringup_done)
        smp_ops->bringup_done();

    dump_numa_cpu_topology();

}

int arch_sd_sibling_asym_packing(void)
{
    if (cpu_has_feature(CPU_FTR_ASYM_SMT)) {
        printk_once(KERN_INFO "Enabling Asymmetric SMT scheduling\n");
        return SD_ASYM_PACKING;
    }
    return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
int __cpu_disable(void)
{
    struct device_node *l2_cache;
    int cpu = smp_processor_id();
    int base, i;
    int err;

    if (!smp_ops->cpu_disable)
        return -ENOSYS;

    err = smp_ops->cpu_disable();
    if (err)
        return err;

    /* Update sibling maps */
    base = cpu_first_thread_sibling(cpu);
    for (i = 0; i < threads_per_core; i++) {
        cpumask_clear_cpu(cpu, cpu_sibling_mask(base + i));
        cpumask_clear_cpu(base + i, cpu_sibling_mask(cpu));
        cpumask_clear_cpu(cpu, cpu_core_mask(base + i));
        cpumask_clear_cpu(base + i, cpu_core_mask(cpu));
    }

    l2_cache = cpu_to_l2cache(cpu);
    for_each_present_cpu(i) {
        struct device_node *np = cpu_to_l2cache(i);
        if (!np)
            continue;
        if (np == l2_cache) {
            cpumask_clear_cpu(cpu, cpu_core_mask(i));
            cpumask_clear_cpu(i, cpu_core_mask(cpu));
        }
        of_node_put(np);
    }
    of_node_put(l2_cache);


    return 0;
}

void __cpu_die(unsigned int cpu)
{
    if (smp_ops->cpu_die)
        smp_ops->cpu_die(cpu);
}

static DEFINE_MUTEX(powerpc_cpu_hotplug_driver_mutex);

void cpu_hotplug_driver_lock()
{
    mutex_lock(&powerpc_cpu_hotplug_driver_mutex);
}

void cpu_hotplug_driver_unlock()
{
    mutex_unlock(&powerpc_cpu_hotplug_driver_mutex);
}

void cpu_die(void)
{
    if (ppc_md.cpu_die)
        ppc_md.cpu_die();

    /* If we return, we re-enter start_secondary */
    start_secondary_resume();
}

#endif