smp.c

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/*
 *  linux/arch/m32r/kernel/smp.c
 *
 *  M32R SMP support routines.
 *
 *  Copyright (c) 2001, 2002  Hitoshi Yamamoto
 *
 *  Taken from i386 version.
 *    (c) 1995 Alan Cox, Building #3 <[email protected]>
 *    (c) 1998-99, 2000 Ingo Molnar <[email protected]>
 *
 *  This code is released under the GNU General Public License version 2 or
 *  later.
 */

#undef DEBUG_SMP

#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/profile.h>
#include <linux/cpu.h>

#include <asm/cacheflush.h>
#include <asm/pgalloc.h>
#include <linux/atomic.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/m32r.h>
#include <asm/tlbflush.h>

/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/
/* Data structures and variables                                             */
/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/

/*
 * For flush_cache_all()
 */
static DEFINE_SPINLOCK(flushcache_lock);
static volatile unsigned long flushcache_cpumask = 0;

/*
 * For flush_tlb_others()
 */
static volatile cpumask_t flush_cpumask;
static struct mm_struct *flush_mm;
static struct vm_area_struct *flush_vma;
static volatile unsigned long flush_va;
static DEFINE_SPINLOCK(tlbstate_lock);
#define FLUSH_ALL 0xffffffff

DECLARE_PER_CPU(int, prof_multiplier);
DECLARE_PER_CPU(int, prof_old_multiplier);
DECLARE_PER_CPU(int, prof_counter);

extern spinlock_t ipi_lock[];

/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/
/* Function Prototypes                                                       */
/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/

void smp_reschedule_interrupt(void);
void smp_flush_cache_all_interrupt(void);

static void flush_tlb_all_ipi(void *);
static void flush_tlb_others(cpumask_t, struct mm_struct *,
    struct vm_area_struct *, unsigned long);

void smp_invalidate_interrupt(void);

static void stop_this_cpu(void *);

void smp_ipi_timer_interrupt(struct pt_regs *);
void smp_local_timer_interrupt(void);

static void send_IPI_allbutself(int, int);
static void send_IPI_mask(const struct cpumask *, int, int);

/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/
/* Rescheduling request Routines                                             */
/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/

/*==========================================================================*
 * Name:         smp_send_reschedule
 *
 * Description:  This routine requests other CPU to execute rescheduling.
 *               1.Send 'RESCHEDULE_IPI' to other CPU.
 *                 Request other CPU to execute 'smp_reschedule_interrupt()'.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    cpu_id - Target CPU ID
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_send_reschedule(int cpu_id)
{
    WARN_ON(cpu_is_offline(cpu_id));
    send_IPI_mask(cpumask_of(cpu_id), RESCHEDULE_IPI, 1);
}

/*==========================================================================*
 * Name:         smp_reschedule_interrupt
 *
 * Description:  This routine executes on CPU which received
 *               'RESCHEDULE_IPI'.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    NONE
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_reschedule_interrupt(void)
{
    scheduler_ipi();
}

/*==========================================================================*
 * Name:         smp_flush_cache_all
 *
 * Description:  This routine sends a 'INVALIDATE_CACHE_IPI' to all other
 *               CPUs in the system.
 *
 * Born on Date: 2003-05-28
 *
 * Arguments:    NONE
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_flush_cache_all(void)
{
    cpumask_t cpumask;
    unsigned long *mask;

    preempt_disable();
    cpumask_copy(&cpumask, cpu_online_mask);
    cpumask_clear_cpu(smp_processor_id(), &cpumask);
    spin_lock(&flushcache_lock);
    mask=cpumask_bits(&cpumask);
    atomic_set_mask(*mask, (atomic_t *)&flushcache_cpumask);
    send_IPI_mask(&cpumask, INVALIDATE_CACHE_IPI, 0);
    _flush_cache_copyback_all();
    while (flushcache_cpumask)
        mb();
    spin_unlock(&flushcache_lock);
    preempt_enable();
}

void smp_flush_cache_all_interrupt(void)
{
    _flush_cache_copyback_all();
    clear_bit(smp_processor_id(), &flushcache_cpumask);
}

/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/
/* TLB flush request Routines                                                */
/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/

/*==========================================================================*
 * Name:         smp_flush_tlb_all
 *
 * Description:  This routine flushes all processes TLBs.
 *               1.Request other CPU to execute 'flush_tlb_all_ipi()'.
 *               2.Execute 'do_flush_tlb_all_local()'.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    NONE
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_flush_tlb_all(void)
{
    unsigned long flags;

    preempt_disable();
    local_irq_save(flags);
    __flush_tlb_all();
    local_irq_restore(flags);
    smp_call_function(flush_tlb_all_ipi, NULL, 1);
    preempt_enable();
}

/*==========================================================================*
 * Name:         flush_tlb_all_ipi
 *
 * Description:  This routine flushes all local TLBs.
 *               1.Execute 'do_flush_tlb_all_local()'.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    *info - not used
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
static void flush_tlb_all_ipi(void *info)
{
    __flush_tlb_all();
}

/*==========================================================================*
 * Name:         smp_flush_tlb_mm
 *
 * Description:  This routine flushes the specified mm context TLB's.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    *mm - a pointer to the mm struct for flush TLB
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_flush_tlb_mm(struct mm_struct *mm)
{
    int cpu_id;
    cpumask_t cpu_mask;
    unsigned long *mmc;
    unsigned long flags;

    preempt_disable();
    cpu_id = smp_processor_id();
    mmc = &mm->context[cpu_id];
    cpumask_copy(&cpu_mask, mm_cpumask(mm));
    cpumask_clear_cpu(cpu_id, &cpu_mask);

    if (*mmc != NO_CONTEXT) {
        local_irq_save(flags);
        *mmc = NO_CONTEXT;
        if (mm == current->mm)
            activate_context(mm);
        else
            cpumask_clear_cpu(cpu_id, mm_cpumask(mm));
        local_irq_restore(flags);
    }
    if (!cpumask_empty(&cpu_mask))
        flush_tlb_others(cpu_mask, mm, NULL, FLUSH_ALL);

    preempt_enable();
}

/*==========================================================================*
 * Name:         smp_flush_tlb_range
 *
 * Description:  This routine flushes a range of pages.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    *mm - a pointer to the mm struct for flush TLB
 *               start - not used
 *               end - not used
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
    unsigned long end)
{
    smp_flush_tlb_mm(vma->vm_mm);
}

/*==========================================================================*
 * Name:         smp_flush_tlb_page
 *
 * Description:  This routine flushes one page.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    *vma - a pointer to the vma struct include va
 *               va - virtual address for flush TLB
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
{
    struct mm_struct *mm = vma->vm_mm;
    int cpu_id;
    cpumask_t cpu_mask;
    unsigned long *mmc;
    unsigned long flags;

    preempt_disable();
    cpu_id = smp_processor_id();
    mmc = &mm->context[cpu_id];
    cpumask_copy(&cpu_mask, mm_cpumask(mm));
    cpumask_clear_cpu(cpu_id, &cpu_mask);

#ifdef DEBUG_SMP
    if (!mm)
        BUG();
#endif

    if (*mmc != NO_CONTEXT) {
        local_irq_save(flags);
        va &= PAGE_MASK;
        va |= (*mmc & MMU_CONTEXT_ASID_MASK);
        __flush_tlb_page(va);
        local_irq_restore(flags);
    }
    if (!cpumask_empty(&cpu_mask))
        flush_tlb_others(cpu_mask, mm, vma, va);

    preempt_enable();
}

/*==========================================================================*
 * Name:         flush_tlb_others
 *
 * Description:  This routine requests other CPU to execute flush TLB.
 *               1.Setup parameters.
 *               2.Send 'INVALIDATE_TLB_IPI' to other CPU.
 *                 Request other CPU to execute 'smp_invalidate_interrupt()'.
 *               3.Wait for other CPUs operation finished.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    cpumask - bitmap of target CPUs
 *               *mm -  a pointer to the mm struct for flush TLB
 *               *vma -  a pointer to the vma struct include va
 *               va - virtual address for flush TLB
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
static void flush_tlb_others(cpumask_t cpumask, struct mm_struct *mm,
    struct vm_area_struct *vma, unsigned long va)
{
    unsigned long *mask;
#ifdef DEBUG_SMP
    unsigned long flags;
    __save_flags(flags);
    if (!(flags & 0x0040))  /* Interrupt Disable NONONO */
        BUG();
#endif /* DEBUG_SMP */

    /*
     * A couple of (to be removed) sanity checks:
     *
     * - we do not send IPIs to not-yet booted CPUs.
     * - current CPU must not be in mask
     * - mask must exist :)
     */
    BUG_ON(cpumask_empty(&cpumask));

    BUG_ON(cpumask_test_cpu(smp_processor_id(), &cpumask));
    BUG_ON(!mm);

    /* If a CPU which we ran on has gone down, OK. */
    cpumask_and(&cpumask, &cpumask, cpu_online_mask);
    if (cpumask_empty(&cpumask))
        return;

    /*
     * i'm not happy about this global shared spinlock in the
     * MM hot path, but we'll see how contended it is.
     * Temporarily this turns IRQs off, so that lockups are
     * detected by the NMI watchdog.
     */
    spin_lock(&tlbstate_lock);

    flush_mm = mm;
    flush_vma = vma;
    flush_va = va;
    mask=cpumask_bits(&cpumask);
    atomic_set_mask(*mask, (atomic_t *)&flush_cpumask);

    /*
     * We have to send the IPI only to
     * CPUs affected.
     */
    send_IPI_mask(&cpumask, INVALIDATE_TLB_IPI, 0);

    while (!cpumask_empty((cpumask_t*)&flush_cpumask)) {
        /* nothing. lockup detection does not belong here */
        mb();
    }

    flush_mm = NULL;
    flush_vma = NULL;
    flush_va = 0;
    spin_unlock(&tlbstate_lock);
}

/*==========================================================================*
 * Name:         smp_invalidate_interrupt
 *
 * Description:  This routine executes on CPU which received
 *               'INVALIDATE_TLB_IPI'.
 *               1.Flush local TLB.
 *               2.Report flush TLB process was finished.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    NONE
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_invalidate_interrupt(void)
{
    int cpu_id = smp_processor_id();
    unsigned long *mmc = &flush_mm->context[cpu_id];

    if (!cpumask_test_cpu(cpu_id, &flush_cpumask))
        return;

    if (flush_va == FLUSH_ALL) {
        *mmc = NO_CONTEXT;
        if (flush_mm == current->active_mm)
            activate_context(flush_mm);
        else
            cpumask_clear_cpu(cpu_id, mm_cpumask(flush_mm));
    } else {
        unsigned long va = flush_va;

        if (*mmc != NO_CONTEXT) {
            va &= PAGE_MASK;
            va |= (*mmc & MMU_CONTEXT_ASID_MASK);
            __flush_tlb_page(va);
        }
    }
    cpumask_clear_cpu(cpu_id, (cpumask_t*)&flush_cpumask);
}

/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/
/* Stop CPU request Routines                                                 */
/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/

/*==========================================================================*
 * Name:         smp_send_stop
 *
 * Description:  This routine requests stop all CPUs.
 *               1.Request other CPU to execute 'stop_this_cpu()'.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    NONE
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_send_stop(void)
{
    smp_call_function(stop_this_cpu, NULL, 0);
}

/*==========================================================================*
 * Name:         stop_this_cpu
 *
 * Description:  This routine halt CPU.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    NONE
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
static void stop_this_cpu(void *dummy)
{
    int cpu_id = smp_processor_id();

    /*
     * Remove this CPU:
     */
    set_cpu_online(cpu_id, false);

    /*
     * PSW IE = 1;
     * IMASK = 0;
     * goto SLEEP
     */
    local_irq_disable();
    outl(0, M32R_ICU_IMASK_PORTL);
    inl(M32R_ICU_IMASK_PORTL);  /* dummy read */
    local_irq_enable();

    for ( ; ; );
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
    send_IPI_mask(mask, CALL_FUNCTION_IPI, 0);
}

void arch_send_call_function_single_ipi(int cpu)
{
    send_IPI_mask(cpumask_of(cpu), CALL_FUNC_SINGLE_IPI, 0);
}

/*==========================================================================*
 * Name:         smp_call_function_interrupt
 *
 * Description:  This routine executes on CPU which received
 *               'CALL_FUNCTION_IPI'.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    NONE
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_call_function_interrupt(void)
{
    irq_enter();
    generic_smp_call_function_interrupt();
    irq_exit();
}

void smp_call_function_single_interrupt(void)
{
    irq_enter();
    generic_smp_call_function_single_interrupt();
    irq_exit();
}

/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/
/* Timer Routines                                                            */
/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/

/*==========================================================================*
 * Name:         smp_send_timer
 *
 * Description:  This routine sends a 'LOCAL_TIMER_IPI' to all other CPUs
 *               in the system.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    NONE
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_send_timer(void)
{
    send_IPI_allbutself(LOCAL_TIMER_IPI, 1);
}

/*==========================================================================*
 * Name:         smp_send_timer
 *
 * Description:  This routine executes on CPU which received
 *               'LOCAL_TIMER_IPI'.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    *regs - a pointer to the saved regster info
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
void smp_ipi_timer_interrupt(struct pt_regs *regs)
{
    struct pt_regs *old_regs;
    old_regs = set_irq_regs(regs);
    irq_enter();
    smp_local_timer_interrupt();
    irq_exit();
    set_irq_regs(old_regs);
}

/*==========================================================================*
 * Name:         smp_local_timer_interrupt
 *
 * Description:  Local timer interrupt handler. It does both profiling and
 *               process statistics/rescheduling.
 *               We do profiling in every local tick, statistics/rescheduling
 *               happen only every 'profiling multiplier' ticks. The default
 *               multiplier is 1 and it can be changed by writing the new
 *               multiplier value into /proc/profile.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    *regs - a pointer to the saved regster info
 *
 * Returns:      void (cannot fail)
 *
 * Original:     arch/i386/kernel/apic.c
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 * 2003-06-24 hy  use per_cpu structure.
 *==========================================================================*/
void smp_local_timer_interrupt(void)
{
    int user = user_mode(get_irq_regs());
    int cpu_id = smp_processor_id();

    /*
     * The profiling function is SMP safe. (nothing can mess
     * around with "current", and the profiling counters are
     * updated with atomic operations). This is especially
     * useful with a profiling multiplier != 1
     */

    profile_tick(CPU_PROFILING);

    if (--per_cpu(prof_counter, cpu_id) <= 0) {
        /*
         * The multiplier may have changed since the last time we got
         * to this point as a result of the user writing to
         * /proc/profile. In this case we need to adjust the APIC
         * timer accordingly.
         *
         * Interrupts are already masked off at this point.
         */
        per_cpu(prof_counter, cpu_id)
            = per_cpu(prof_multiplier, cpu_id);
        if (per_cpu(prof_counter, cpu_id)
            != per_cpu(prof_old_multiplier, cpu_id))
        {
            per_cpu(prof_old_multiplier, cpu_id)
                = per_cpu(prof_counter, cpu_id);
        }

        update_process_times(user);
    }
}

/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/
/* Send IPI Routines                                                         */
/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/

/*==========================================================================*
 * Name:         send_IPI_allbutself
 *
 * Description:  This routine sends a IPI to all other CPUs in the system.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    ipi_num - Number of IPI
 *               try -  0 : Send IPI certainly.
 *                     !0 : The following IPI is not sent when Target CPU
 *                          has not received the before IPI.
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
static void send_IPI_allbutself(int ipi_num, int try)
{
    cpumask_t cpumask;

    cpumask_copy(&cpumask, cpu_online_mask);
    cpumask_clear_cpu(smp_processor_id(), &cpumask);

    send_IPI_mask(&cpumask, ipi_num, try);
}

/*==========================================================================*
 * Name:         send_IPI_mask
 *
 * Description:  This routine sends a IPI to CPUs in the system.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    cpu_mask - Bitmap of target CPUs logical ID
 *               ipi_num - Number of IPI
 *               try -  0 : Send IPI certainly.
 *                     !0 : The following IPI is not sent when Target CPU
 *                          has not received the before IPI.
 *
 * Returns:      void (cannot fail)
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
static void send_IPI_mask(const struct cpumask *cpumask, int ipi_num, int try)
{
    cpumask_t physid_mask, tmp;
    int cpu_id, phys_id;
    int num_cpus = num_online_cpus();

    if (num_cpus <= 1)  /* NO MP */
        return;

    cpumask_and(&tmp, cpumask, cpu_online_mask);
    BUG_ON(!cpumask_equal(cpumask, &tmp));

    cpumask_clear(&physid_mask);
    for_each_cpu(cpu_id, cpumask) {
        if ((phys_id = cpu_to_physid(cpu_id)) != -1)
            cpumask_set_cpu(phys_id, &physid_mask);
    }

    send_IPI_mask_phys(&physid_mask, ipi_num, try);
}

/*==========================================================================*
 * Name:         send_IPI_mask_phys
 *
 * Description:  This routine sends a IPI to other CPUs in the system.
 *
 * Born on Date: 2002.02.05
 *
 * Arguments:    cpu_mask - Bitmap of target CPUs physical ID
 *               ipi_num - Number of IPI
 *               try -  0 : Send IPI certainly.
 *                     !0 : The following IPI is not sent when Target CPU
 *                          has not received the before IPI.
 *
 * Returns:      IPICRi regster value.
 *
 * Modification log:
 * Date       Who Description
 * ---------- --- --------------------------------------------------------
 *
 *==========================================================================*/
unsigned long send_IPI_mask_phys(const cpumask_t *physid_mask, int ipi_num,
    int try)
{
    spinlock_t *ipilock;
    volatile unsigned long *ipicr_addr;
    unsigned long ipicr_val;
    unsigned long my_physid_mask;
    unsigned long mask = cpumask_bits(physid_mask)[0];


    if (mask & ~physids_coerce(phys_cpu_present_map))
        BUG();
    if (ipi_num >= NR_IPIS || ipi_num < 0)
        BUG();

    mask <<= IPI_SHIFT;
    ipilock = &ipi_lock[ipi_num];
    ipicr_addr = (volatile unsigned long *)(M32R_ICU_IPICR_ADDR
        + (ipi_num << 2));
    my_physid_mask = ~(1 << smp_processor_id());

    /*
     * lock ipi_lock[i]
     * check IPICRi == 0
     * write IPICRi (send IPIi)
     * unlock ipi_lock[i]
     */
    spin_lock(ipilock);
    __asm__ __volatile__ (
        ";; CHECK IPICRi == 0       \n\t"
        ".fillinsn          \n"
        "1:             \n\t"
        "ld %0, @%1         \n\t"
        "and    %0, %4          \n\t"
        "beqz   %0, 2f          \n\t"
        "bnez   %3, 3f          \n\t"
        "bra    1b          \n\t"
        ";; WRITE IPICRi (send IPIi)    \n\t"
        ".fillinsn          \n"
        "2:             \n\t"
        "st %2, @%1         \n\t"
        ".fillinsn          \n"
        "3:             \n\t"
        : "=&r"(ipicr_val)
        : "r"(ipicr_addr), "r"(mask), "r"(try), "r"(my_physid_mask)
        : "memory"
    );
    spin_unlock(ipilock);

    return ipicr_val;
}