initial commit with v2.6.9

[linux-2.6.9-moxart.git] / arch / ppc64 / kernel / smp.c

/*
 * SMP support for ppc.
 *
 * Written by Cort Dougan (cort@cs.nmt.edu) borrowing a great
 * deal of code from the sparc and intel versions.
 *
 * Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
 *
 * 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/config.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/cache.h>
#include <linux/err.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>

#include <asm/ptrace.h>
#include <asm/atomic.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/naca.h>
#include <asm/paca.h>
#include <asm/iSeries/LparData.h>
#include <asm/iSeries/HvCall.h>
#include <asm/iSeries/HvCallCfg.h>
#include <asm/time.h>
#include <asm/ppcdebug.h>
#include "open_pic.h"
#include <asm/machdep.h>
#include <asm/xics.h>
#include <asm/cputable.h>
#include <asm/system.h>
#include <asm/rtas.h>
#include <asm/plpar_wrappers.h>

#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif

int smp_threads_ready;
unsigned long cache_decay_ticks;

cpumask_t cpu_possible_map = CPU_MASK_NONE;
cpumask_t cpu_online_map = CPU_MASK_NONE;
cpumask_t cpu_sibling_map[NR_CPUS] = { [0 ... NR_CPUS-1] = CPU_MASK_NONE };

EXPORT_SYMBOL(cpu_online_map);
EXPORT_SYMBOL(cpu_possible_map);

struct smp_ops_t *smp_ops;

static volatile unsigned int cpu_callin_map[NR_CPUS];

extern unsigned char stab_array[];

extern int cpu_idle(void *unused);
void smp_call_function_interrupt(void);
extern long register_vpa(unsigned long flags, unsigned long proc,
                         unsigned long vpa);

int smt_enabled_at_boot = 1;

/* Low level assembly function used to backup CPU 0 state */
extern void __save_cpu_setup(void);

extern void pseries_secondary_smp_init(unsigned long); 

#ifdef CONFIG_PPC_ISERIES
static unsigned long iSeries_smp_message[NR_CPUS];

void iSeries_smp_message_recv( struct pt_regs * regs )
{
        int cpu = smp_processor_id();
        int msg;

        if ( num_online_cpus() < 2 )
                return;

        for ( msg = 0; msg < 4; ++msg )
                if ( test_and_clear_bit( msg, &iSeries_smp_message[cpu] ) )
                        smp_message_recv( msg, regs );
}

static inline void smp_iSeries_do_message(int cpu, int msg)
{
        set_bit(msg, &iSeries_smp_message[cpu]);
        HvCall_sendIPI(&(paca[cpu]));
}

static void smp_iSeries_message_pass(int target, int msg)
{
        int i;

        if (target < NR_CPUS)
                smp_iSeries_do_message(target, msg);
        else {
                for_each_online_cpu(i) {
                        if (target == MSG_ALL_BUT_SELF
                            && i == smp_processor_id())
                                continue;
                        smp_iSeries_do_message(i, msg);
                }
        }
}

static int smp_iSeries_numProcs(void)
{
        unsigned np, i;

        np = 0;
        for (i=0; i < NR_CPUS; ++i) {
                if (paca[i].lppaca.xDynProcStatus < 2) {
                        cpu_set(i, cpu_possible_map);
                        cpu_set(i, cpu_present_map);
                        ++np;
                }
        }
        return np;
}

static int smp_iSeries_probe(void)
{
        unsigned i;
        unsigned np = 0;

        for (i=0; i < NR_CPUS; ++i) {
                if (paca[i].lppaca.xDynProcStatus < 2) {
                        /*paca[i].active = 1;*/
                        ++np;
                }
        }

        return np;
}

static void smp_iSeries_kick_cpu(int nr)
{
        BUG_ON(nr < 0 || nr >= NR_CPUS);

        /* Verify that our partition has a processor nr */
        if (paca[nr].lppaca.xDynProcStatus >= 2)
                return;

        /* 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 in iSeries_head.S
         */
        paca[nr].cpu_start = 1;
}

static void __devinit smp_iSeries_setup_cpu(int nr)
{
}

static struct smp_ops_t iSeries_smp_ops = {
        .message_pass = smp_iSeries_message_pass,
        .probe        = smp_iSeries_probe,
        .kick_cpu     = smp_iSeries_kick_cpu,
        .setup_cpu    = smp_iSeries_setup_cpu,
};

/* This is called very early. */
void __init smp_init_iSeries(void)
{
        smp_ops = &iSeries_smp_ops;
        systemcfg->processorCount       = smp_iSeries_numProcs();
}
#endif

#ifdef CONFIG_PPC_MULTIPLATFORM
void smp_openpic_message_pass(int target, int msg)
{
        /* make sure we're sending something that translates to an IPI */
        if ( msg > 0x3 ){
                printk("SMP %d: smp_message_pass: unknown msg %d\n",
                       smp_processor_id(), msg);
                return;
        }
        switch ( target )
        {
        case MSG_ALL:
                openpic_cause_IPI(msg, 0xffffffff);
                break;
        case MSG_ALL_BUT_SELF:
                openpic_cause_IPI(msg,
                                  0xffffffff & ~(1 << smp_processor_id()));
                break;
        default:
                openpic_cause_IPI(msg, 1<<target);
                break;
        }
}

static int __init smp_openpic_probe(void)
{
        int nr_cpus;

        nr_cpus = cpus_weight(cpu_possible_map);

        if (nr_cpus > 1)
                openpic_request_IPIs();

        return nr_cpus;
}

static void __devinit smp_openpic_setup_cpu(int cpu)
{
        do_openpic_setup_cpu();
}

#endif /* CONFIG_PPC_MULTIPLATFORM */

#ifdef CONFIG_PPC_PSERIES

/* Get state of physical CPU.
 * Return codes:
 *      0       - The processor is in the RTAS stopped state
 *      1       - stop-self is in progress
 *      2       - The processor is not in the RTAS stopped state
 *      -1      - Hardware Error
 *      -2      - Hardware Busy, Try again later.
 */
int query_cpu_stopped(unsigned int pcpu)
{
        int cpu_status;
        int status, qcss_tok;

        DBG(" -> query_cpu_stopped(%d)\n", pcpu);
        qcss_tok = rtas_token("query-cpu-stopped-state");
        if (qcss_tok == RTAS_UNKNOWN_SERVICE)
                return -1;
        status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
        if (status != 0) {
                printk(KERN_ERR
                       "RTAS query-cpu-stopped-state failed: %i\n", status);
                return status;
        }

        DBG(" <- query_cpu_stopped(), status: %d\n", cpu_status);

        return cpu_status;
}

#ifdef CONFIG_HOTPLUG_CPU

int __cpu_disable(void)
{
        /* FIXME: go put this in a header somewhere */
        extern void xics_migrate_irqs_away(void);

        systemcfg->processorCount--;

        /*fix boot_cpuid here*/
        if (smp_processor_id() == boot_cpuid)
                boot_cpuid = any_online_cpu(cpu_online_map);

        /* FIXME: abstract this to not be platform specific later on */
        xics_migrate_irqs_away();
        return 0;
}

void __cpu_die(unsigned int cpu)
{
        int tries;
        int cpu_status;
        unsigned int pcpu = get_hard_smp_processor_id(cpu);

        for (tries = 0; tries < 25; tries++) {
                cpu_status = query_cpu_stopped(pcpu);
                if (cpu_status == 0 || cpu_status == -1)
                        break;
                set_current_state(TASK_UNINTERRUPTIBLE);
                schedule_timeout(HZ/5);
        }
        if (cpu_status != 0) {
                printk("Querying DEAD? cpu %i (%i) shows %i\n",
                       cpu, pcpu, cpu_status);
        }

        /* Isolation and deallocation are definatly done by
         * drslot_chrp_cpu.  If they were not they would be
         * done here.  Change isolate state to Isolate and
         * change allocation-state to Unusable.
         */
        paca[cpu].cpu_start = 0;

        /* So we can recognize if it fails to come up next time. */
        cpu_callin_map[cpu] = 0;
}

/* Kill this cpu */
void cpu_die(void)
{
        local_irq_disable();
        /* Some hardware requires clearing the CPPR, while other hardware does not
         * it is safe either way
         */
        pSeriesLP_cppr_info(0, 0);
        rtas_stop_self();
        /* Should never get here... */
        BUG();
        for(;;);
}

/* Search all cpu device nodes for an offline logical cpu.  If a
 * device node has a "ibm,my-drc-index" property (meaning this is an
 * LPAR), paranoid-check whether we own the cpu.  For each "thread"
 * of a cpu, if it is offline and has the same hw index as before,
 * grab that in preference.
 */
static unsigned int find_physical_cpu_to_start(unsigned int old_hwindex)
{
        struct device_node *np = NULL;
        unsigned int best = -1U;

        while ((np = of_find_node_by_type(np, "cpu"))) {
                int nr_threads, len;
                u32 *index = (u32 *)get_property(np, "ibm,my-drc-index", NULL);
                u32 *tid = (u32 *)
                        get_property(np, "ibm,ppc-interrupt-server#s", &len);

                if (!tid)
                        tid = (u32 *)get_property(np, "reg", &len);

                if (!tid)
                        continue;

                /* If there is a drc-index, make sure that we own
                 * the cpu.
                 */
                if (index) {
                        int state;
                        int rc = rtas_get_sensor(9003, *index, &state);
                        if (rc != 0 || state != 1)
                                continue;
                }

                nr_threads = len / sizeof(u32);

                while (nr_threads--) {
                        if (0 == query_cpu_stopped(tid[nr_threads])) {
                                best = tid[nr_threads];
                                if (best == old_hwindex)
                                        goto out;
                        }
                }
        }
out:
        of_node_put(np);
        return best;
}

/**
 * smp_startup_cpu() - start the given cpu
 *
 * At boot time, there is nothing to do.  At run-time, call RTAS with
 * the appropriate start location, if the cpu is in the RTAS stopped
 * state.
 *
 * Returns:
 *      0       - failure
 *      1       - success
 */
static inline int __devinit smp_startup_cpu(unsigned int lcpu)
{
        int status;
        unsigned long start_here = __pa((u32)*((unsigned long *)
                                               pseries_secondary_smp_init));
        unsigned int pcpu;

        /* At boot time the cpus are already spinning in hold
         * loops, so nothing to do. */
        if (system_state < SYSTEM_RUNNING)
                return 1;

        pcpu = find_physical_cpu_to_start(get_hard_smp_processor_id(lcpu));
        if (pcpu == -1U) {
                printk(KERN_INFO "No more cpus available, failing\n");
                return 0;
        }

        /* Fixup atomic count: it exited inside IRQ handler. */
        paca[lcpu].__current->thread_info->preempt_count        = 0;

        /* At boot this is done in prom.c. */
        paca[lcpu].hw_cpu_id = pcpu;

        status = rtas_call(rtas_token("start-cpu"), 3, 1, NULL,
                           pcpu, start_here, lcpu);
        if (status != 0) {
                printk(KERN_ERR "start-cpu failed: %i\n", status);
                return 0;
        }
        return 1;
}
#else /* ... CONFIG_HOTPLUG_CPU */
static inline int __devinit smp_startup_cpu(unsigned int lcpu)
{
        return 1;
}
#endif /* CONFIG_HOTPLUG_CPU */

static void smp_pSeries_kick_cpu(int nr)
{
        BUG_ON(nr < 0 || nr >= NR_CPUS);

        if (!smp_startup_cpu(nr))
                return;

        /*
         * 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
         */
        paca[nr].cpu_start = 1;
}
#endif /* CONFIG_PPC_PSERIES */

static void __init smp_space_timers(unsigned int max_cpus)
{
        int i;
        unsigned long offset = tb_ticks_per_jiffy / max_cpus;
        unsigned long previous_tb = paca[boot_cpuid].next_jiffy_update_tb;

        for_each_cpu(i) {
                if (i != boot_cpuid) {
                        paca[i].next_jiffy_update_tb =
                                previous_tb + offset;
                        previous_tb = paca[i].next_jiffy_update_tb;
                }
        }
}

#ifdef CONFIG_PPC_PSERIES
static void vpa_init(int cpu)
{
        unsigned long flags, pcpu = get_hard_smp_processor_id(cpu);

        /* Register the Virtual Processor Area (VPA) */
        flags = 1UL << (63 - 18);
        register_vpa(flags, pcpu, __pa((unsigned long)&(paca[cpu].lppaca)));
}

static inline void smp_xics_do_message(int cpu, int msg)
{
        set_bit(msg, &xics_ipi_message[cpu].value);
        mb();
        xics_cause_IPI(cpu);
}

static void smp_xics_message_pass(int target, int msg)
{
        unsigned int i;

        if (target < NR_CPUS) {
                smp_xics_do_message(target, msg);
        } else {
                for_each_online_cpu(i) {
                        if (target == MSG_ALL_BUT_SELF
                            && i == smp_processor_id())
                                continue;
                        smp_xics_do_message(i, msg);
                }
        }
}

extern void xics_request_IPIs(void);

static int __init smp_xics_probe(void)
{
#ifdef CONFIG_SMP
        xics_request_IPIs();
#endif

        return cpus_weight(cpu_possible_map);
}

static void __devinit smp_xics_setup_cpu(int cpu)
{
        if (cpu != boot_cpuid)
                xics_setup_cpu();
}

static spinlock_t timebase_lock = SPIN_LOCK_UNLOCKED;
static unsigned long timebase = 0;

static void __devinit pSeries_give_timebase(void)
{
        spin_lock(&timebase_lock);
        rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
        timebase = get_tb();
        spin_unlock(&timebase_lock);

        while (timebase)
                barrier();
        rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
}

static void __devinit pSeries_take_timebase(void)
{
        while (!timebase)
                barrier();
        spin_lock(&timebase_lock);
        set_tb(timebase >> 32, timebase & 0xffffffff);
        timebase = 0;
        spin_unlock(&timebase_lock);
}

static struct smp_ops_t pSeries_openpic_smp_ops = {
        .message_pass   = smp_openpic_message_pass,
        .probe          = smp_openpic_probe,
        .kick_cpu       = smp_pSeries_kick_cpu,
        .setup_cpu      = smp_openpic_setup_cpu,
};

static struct smp_ops_t pSeries_xics_smp_ops = {
        .message_pass   = smp_xics_message_pass,
        .probe          = smp_xics_probe,
        .kick_cpu       = smp_pSeries_kick_cpu,
        .setup_cpu      = smp_xics_setup_cpu,
};

/* This is called very early */
void __init smp_init_pSeries(void)
{
        int ret, i;

        DBG(" -> smp_init_pSeries()\n");

        if (naca->interrupt_controller == IC_OPEN_PIC)
                smp_ops = &pSeries_openpic_smp_ops;
        else
                smp_ops = &pSeries_xics_smp_ops;

        /* Start secondary threads on SMT systems; primary threads
         * are already in the running state.
         */
        for_each_present_cpu(i) {
                if (query_cpu_stopped(get_hard_smp_processor_id(i)) == 0) {
                        printk("%16.16x : starting thread\n", i);
                        DBG("%16.16x : starting thread\n", i);
                        rtas_call(rtas_token("start-cpu"), 3, 1, &ret,
                                  get_hard_smp_processor_id(i),
                                  __pa((u32)*((unsigned long *)
                                              pseries_secondary_smp_init)),
                                  i);
                }
        }

        if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR)
                vpa_init(boot_cpuid);

        /* Non-lpar has additional take/give timebase */
        if (systemcfg->platform == PLATFORM_PSERIES) {
                smp_ops->give_timebase = pSeries_give_timebase;
                smp_ops->take_timebase = pSeries_take_timebase;
        }


        DBG(" <- smp_init_pSeries()\n");
}
#endif /* CONFIG_PPC_PSERIES */

void smp_local_timer_interrupt(struct pt_regs * regs)
{
        update_process_times(user_mode(regs));
}

void smp_message_recv(int msg, struct pt_regs *regs)
{
        switch(msg) {
        case PPC_MSG_CALL_FUNCTION:
                smp_call_function_interrupt();
                break;
        case PPC_MSG_RESCHEDULE: 
                /* XXX Do we have to do this? */
                set_need_resched();
                break;
#if 0
        case PPC_MSG_MIGRATE_TASK:
                /* spare */
                break;
#endif
#ifdef CONFIG_DEBUGGER
        case PPC_MSG_DEBUGGER_BREAK:
                debugger_ipi(regs);
                break;
#endif
        default:
                printk("SMP %d: smp_message_recv(): unknown msg %d\n",
                       smp_processor_id(), msg);
                break;
        }
}

void smp_send_reschedule(int cpu)
{
        smp_ops->message_pass(cpu, PPC_MSG_RESCHEDULE);
}

#ifdef CONFIG_DEBUGGER
void smp_send_debugger_break(int cpu)
{
        smp_ops->message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
}
#endif

static void stop_this_cpu(void *dummy)
{
        local_irq_disable();
        while (1)
                ;
}

void smp_send_stop(void)
{
        smp_call_function(stop_this_cpu, NULL, 1, 0);
}

/*
 * Structure and data for smp_call_function(). This is designed to minimise
 * static memory requirements. It also looks cleaner.
 * Stolen from the i386 version.
 */
static spinlock_t call_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;

static struct call_data_struct {
        void (*func) (void *info);
        void *info;
        atomic_t started;
        atomic_t finished;
        int wait;
} *call_data;

/* delay of at least 8 seconds on 1GHz cpu */
#define SMP_CALL_TIMEOUT (1UL << (30 + 3))

/*
 * This function sends a 'generic call function' IPI to all other CPUs
 * in the system.
 *
 * [SUMMARY] Run a function on all other CPUs.
 * <func> The function to run. This must be fast and non-blocking.
 * <info> An arbitrary pointer to pass to the function.
 * <nonatomic> currently unused.
 * <wait> If true, wait (atomically) until function has completed on other CPUs.
 * [RETURNS] 0 on success, else a negative status code. Does not return until
 * remote CPUs are nearly ready to execute <<func>> or are or have executed.
 *
 * You must not call this function with disabled interrupts or from a
 * hardware interrupt handler or from a bottom half handler.
 */
int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
                       int wait)
{ 
        struct call_data_struct data;
        int ret = -1, cpus;
        unsigned long timeout;

        /* Can deadlock when called with interrupts disabled */
        WARN_ON(irqs_disabled());

        data.func = func;
        data.info = info;
        atomic_set(&data.started, 0);
        data.wait = wait;
        if (wait)
                atomic_set(&data.finished, 0);

        spin_lock(&call_lock);
        /* Must grab online cpu count with preempt disabled, otherwise
         * it can change. */
        cpus = num_online_cpus() - 1;
        if (!cpus) {
                ret = 0;
                goto out;
        }

        call_data = &data;
        wmb();
        /* Send a message to all other CPUs and wait for them to respond */
        smp_ops->message_pass(MSG_ALL_BUT_SELF, PPC_MSG_CALL_FUNCTION);

        /* Wait for response */
        timeout = SMP_CALL_TIMEOUT;
        while (atomic_read(&data.started) != cpus) {
                HMT_low();
                if (--timeout == 0) {
                        printk("smp_call_function on cpu %d: other cpus not "
                               "responding (%d)\n", smp_processor_id(),
                               atomic_read(&data.started));
                        debugger(NULL);
                        goto out;
                }
        }

        if (wait) {
                timeout = SMP_CALL_TIMEOUT;
                while (atomic_read(&data.finished) != cpus) {
                        HMT_low();
                        if (--timeout == 0) {
                                printk("smp_call_function on cpu %d: other "
                                       "cpus not finishing (%d/%d)\n",
                                       smp_processor_id(),
                                       atomic_read(&data.finished),
                                       atomic_read(&data.started));
                                debugger(NULL);
                                goto out;
                        }
                }
        }

        ret = 0;

out:
        call_data = NULL;
        HMT_medium();
        spin_unlock(&call_lock);
        return ret;
}

EXPORT_SYMBOL(smp_call_function);

void smp_call_function_interrupt(void)
{
        void (*func) (void *info);
        void *info;
        int wait;

        /* call_data will be NULL if the sender timed out while
         * waiting on us to receive the call.
         */
        if (!call_data)
                return;

        func = call_data->func;
        info = call_data->info;
        wait = call_data->wait;

        if (!wait)
                smp_mb__before_atomic_inc();

        /*
         * Notify initiating CPU that I've grabbed the data and am
         * about to execute the function
         */
        atomic_inc(&call_data->started);
        /*
         * At this point the info structure may be out of scope unless wait==1
         */
        (*func)(info);
        if (wait) {
                smp_mb__before_atomic_inc();
                atomic_inc(&call_data->finished);
        }
}

extern unsigned long decr_overclock;
extern struct gettimeofday_struct do_gtod;

struct thread_info *current_set[NR_CPUS];

DECLARE_PER_CPU(unsigned int, pvr);

static void __devinit smp_store_cpu_info(int id)
{
        per_cpu(pvr, id) = mfspr(SPRN_PVR);
}

static void __init smp_create_idle(unsigned int cpu)
{
        struct task_struct *p;

        /* create a process for the processor */
        p = fork_idle(cpu);
        if (IS_ERR(p))
                panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
        paca[cpu].__current = p;
        current_set[cpu] = p->thread_info;
}

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

        /* 
         * 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;

#ifndef CONFIG_PPC_ISERIES
        paca[boot_cpuid].next_jiffy_update_tb = tb_last_stamp = get_tb();

        /*
         * Should update do_gtod.stamp_xsec.
         * For now we leave it which means the time can be some
         * number of msecs off until someone does a settimeofday()
         */
        do_gtod.tb_orig_stamp = tb_last_stamp;
        systemcfg->tb_orig_stamp = tb_last_stamp;
#endif

        max_cpus = smp_ops->probe();
 
        /* Backup CPU 0 state if necessary */
        __save_cpu_setup();

        smp_space_timers(max_cpus);

        for_each_cpu(cpu)
                if (cpu != boot_cpuid)
                        smp_create_idle(cpu);
}

void __devinit smp_prepare_boot_cpu(void)
{
        BUG_ON(smp_processor_id() != boot_cpuid);

        cpu_set(boot_cpuid, cpu_online_map);

        paca[boot_cpuid].__current = current;
        current_set[boot_cpuid] = current->thread_info;
}

int __devinit __cpu_up(unsigned int cpu)
{
        int c;

        /* At boot, don't bother with non-present cpus -JSCHOPP */
        if (system_state < SYSTEM_RUNNING && !cpu_present(cpu))
                return -ENOENT;

        paca[cpu].default_decr = tb_ticks_per_jiffy / decr_overclock;

        if (!(cur_cpu_spec->cpu_features & CPU_FTR_SLB)) {
                void *tmp;

                /* maximum of 48 CPUs on machines with a segment table */
                if (cpu >= 48)
                        BUG();

                tmp = &stab_array[PAGE_SIZE * cpu];
                memset(tmp, 0, PAGE_SIZE); 
                paca[cpu].stab_addr = (unsigned long)tmp;
                paca[cpu].stab_real = virt_to_abs(tmp);
        }

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

        /* wake up cpus */
        smp_ops->kick_cpu(cpu);

        /*
         * 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 = 5000; 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 = 25; c && !cpu_callin_map[cpu]; c--) {
                        set_current_state(TASK_UNINTERRUPTIBLE);
                        schedule_timeout(HZ/5);
                }
#endif

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

        printk("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;
}

extern unsigned int default_distrib_server;
/* Activate a secondary processor. */
int __devinit start_secondary(void *unused)
{
        unsigned int cpu = smp_processor_id();

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

        smp_store_cpu_info(cpu);
        set_dec(paca[cpu].default_decr);
        cpu_callin_map[cpu] = 1;

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

#ifdef CONFIG_PPC_PSERIES
        if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) {
                vpa_init(cpu); 
        }

#ifdef CONFIG_IRQ_ALL_CPUS
        /* Put the calling processor into the GIQ.  This is really only
         * necessary from a secondary thread as the OF start-cpu interface
         * performs this function for us on primary threads.
         */
        /* TODO: 9005 is #defined in rtas-proc.c -- move to a header */
        rtas_set_indicator(9005, default_distrib_server, 1);
#endif
#endif

        spin_lock(&call_lock);
        cpu_set(cpu, cpu_online_map);
        spin_unlock(&call_lock);

        local_irq_enable();

        return cpu_idle(NULL);
}

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

void __init smp_cpus_done(unsigned int max_cpus)
{
        cpumask_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
         */
        old_mask = current->cpus_allowed;
        set_cpus_allowed(current, cpumask_of_cpu(boot_cpuid));
        
        smp_ops->setup_cpu(boot_cpuid);

        /* XXX fix this, xics currently relies on it - Anton */
        smp_threads_ready = 1;

        set_cpus_allowed(current, old_mask);

        /*
         * We know at boot the maximum number of cpus we can add to
         * a partition and set cpu_possible_map accordingly. cpu_present_map
         * needs to match for the hotplug code to allow us to hot add
         * any offline cpus.
         */
        cpu_present_map = cpu_possible_map;
}