Blackfin: fix deadlock in SMP IPI handler

[linux-2.6/btrfs-unstable.git] / arch / blackfin / mach-common / smp.c

/*
 * File:         arch/blackfin/kernel/smp.c
 * Author:       Philippe Gerum <rpm@xenomai.org>
 * IPI management based on arch/arm/kernel/smp.c.
 *
 *               Copyright 2007 Analog Devices Inc.
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see the file COPYING, or write
 * to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#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/cpu.h>
#include <linux/smp.h>
#include <linux/seq_file.h>
#include <linux/irq.h>
#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/cpu.h>
#include <asm/time.h>
#include <linux/err.h>

/*
 * Anomaly notes:
 * 05000120 - we always define corelock as 32-bit integer in L2
 */
struct corelock_slot corelock __attribute__ ((__section__(".l2.bss")));

void __cpuinitdata *init_retx_coreb, *init_saved_retx_coreb,
        *init_saved_seqstat_coreb, *init_saved_icplb_fault_addr_coreb,
        *init_saved_dcplb_fault_addr_coreb;

cpumask_t cpu_possible_map;
EXPORT_SYMBOL(cpu_possible_map);

cpumask_t cpu_online_map;
EXPORT_SYMBOL(cpu_online_map);

#define BFIN_IPI_RESCHEDULE   0
#define BFIN_IPI_CALL_FUNC    1
#define BFIN_IPI_CPU_STOP     2

struct blackfin_flush_data {
        unsigned long start;
        unsigned long end;
};

void *secondary_stack;


struct smp_call_struct {
        void (*func)(void *info);
        void *info;
        int wait;
        cpumask_t pending;
        cpumask_t waitmask;
};

static struct blackfin_flush_data smp_flush_data;

static DEFINE_SPINLOCK(stop_lock);

struct ipi_message {
        struct list_head list;
        unsigned long type;
        struct smp_call_struct call_struct;
};

struct ipi_message_queue {
        struct list_head head;
        spinlock_t lock;
        unsigned long count;
};

static DEFINE_PER_CPU(struct ipi_message_queue, ipi_msg_queue);

static void ipi_cpu_stop(unsigned int cpu)
{
        spin_lock(&stop_lock);
        printk(KERN_CRIT "CPU%u: stopping\n", cpu);
        dump_stack();
        spin_unlock(&stop_lock);

        cpu_clear(cpu, cpu_online_map);

        local_irq_disable();

        while (1)
                SSYNC();
}

static void ipi_flush_icache(void *info)
{
        struct blackfin_flush_data *fdata = info;

        /* Invalidate the memory holding the bounds of the flushed region. */
        blackfin_dcache_invalidate_range((unsigned long)fdata,
                                         (unsigned long)fdata + sizeof(*fdata));

        blackfin_icache_flush_range(fdata->start, fdata->end);
}

static void ipi_call_function(unsigned int cpu, struct ipi_message *msg)
{
        int wait;
        void (*func)(void *info);
        void *info;
        func = msg->call_struct.func;
        info = msg->call_struct.info;
        wait = msg->call_struct.wait;
        cpu_clear(cpu, msg->call_struct.pending);
        func(info);
        if (wait)
                cpu_clear(cpu, msg->call_struct.waitmask);
        else
                kfree(msg);
}

static irqreturn_t ipi_handler(int irq, void *dev_instance)
{
        struct ipi_message *msg;
        struct ipi_message_queue *msg_queue;
        unsigned int cpu = smp_processor_id();

        platform_clear_ipi(cpu);

        msg_queue = &__get_cpu_var(ipi_msg_queue);
        msg_queue->count++;

        spin_lock(&msg_queue->lock);
        while (!list_empty(&msg_queue->head)) {
                msg = list_entry(msg_queue->head.next, typeof(*msg), list);
                list_del(&msg->list);
                switch (msg->type) {
                case BFIN_IPI_RESCHEDULE:
                        /* That's the easiest one; leave it to
                         * return_from_int. */
                        kfree(msg);
                        break;
                case BFIN_IPI_CALL_FUNC:
                        spin_unlock(&msg_queue->lock);
                        ipi_call_function(cpu, msg);
                        spin_lock(&msg_queue->lock);
                        break;
                case BFIN_IPI_CPU_STOP:
                        spin_unlock(&msg_queue->lock);
                        ipi_cpu_stop(cpu);
                        spin_lock(&msg_queue->lock);
                        kfree(msg);
                        break;
                default:
                        printk(KERN_CRIT "CPU%u: Unknown IPI message \
                        0x%lx\n", cpu, msg->type);
                        kfree(msg);
                        break;
                }
        }
        spin_unlock(&msg_queue->lock);
        return IRQ_HANDLED;
}

static void ipi_queue_init(void)
{
        unsigned int cpu;
        struct ipi_message_queue *msg_queue;
        for_each_possible_cpu(cpu) {
                msg_queue = &per_cpu(ipi_msg_queue, cpu);
                INIT_LIST_HEAD(&msg_queue->head);
                spin_lock_init(&msg_queue->lock);
                msg_queue->count = 0;
        }
}

int smp_call_function(void (*func)(void *info), void *info, int wait)
{
        unsigned int cpu;
        cpumask_t callmap;
        unsigned long flags;
        struct ipi_message_queue *msg_queue;
        struct ipi_message *msg;

        callmap = cpu_online_map;
        cpu_clear(smp_processor_id(), callmap);
        if (cpus_empty(callmap))
                return 0;

        msg = kmalloc(sizeof(*msg), GFP_ATOMIC);
        INIT_LIST_HEAD(&msg->list);
        msg->call_struct.func = func;
        msg->call_struct.info = info;
        msg->call_struct.wait = wait;
        msg->call_struct.pending = callmap;
        msg->call_struct.waitmask = callmap;
        msg->type = BFIN_IPI_CALL_FUNC;

        for_each_cpu_mask(cpu, callmap) {
                msg_queue = &per_cpu(ipi_msg_queue, cpu);
                spin_lock_irqsave(&msg_queue->lock, flags);
                list_add_tail(&msg->list, &msg_queue->head);
                spin_unlock_irqrestore(&msg_queue->lock, flags);
                platform_send_ipi_cpu(cpu);
        }
        if (wait) {
                while (!cpus_empty(msg->call_struct.waitmask))
                        blackfin_dcache_invalidate_range(
                                (unsigned long)(&msg->call_struct.waitmask),
                                (unsigned long)(&msg->call_struct.waitmask));
                kfree(msg);
        }
        return 0;
}
EXPORT_SYMBOL_GPL(smp_call_function);

int smp_call_function_single(int cpuid, void (*func) (void *info), void *info,
                                int wait)
{
        unsigned int cpu = cpuid;
        cpumask_t callmap;
        unsigned long flags;
        struct ipi_message_queue *msg_queue;
        struct ipi_message *msg;

        if (cpu_is_offline(cpu))
                return 0;
        cpus_clear(callmap);
        cpu_set(cpu, callmap);

        msg = kmalloc(sizeof(*msg), GFP_ATOMIC);
        INIT_LIST_HEAD(&msg->list);
        msg->call_struct.func = func;
        msg->call_struct.info = info;
        msg->call_struct.wait = wait;
        msg->call_struct.pending = callmap;
        msg->call_struct.waitmask = callmap;
        msg->type = BFIN_IPI_CALL_FUNC;

        msg_queue = &per_cpu(ipi_msg_queue, cpu);
        spin_lock_irqsave(&msg_queue->lock, flags);
        list_add_tail(&msg->list, &msg_queue->head);
        spin_unlock_irqrestore(&msg_queue->lock, flags);
        platform_send_ipi_cpu(cpu);

        if (wait) {
                while (!cpus_empty(msg->call_struct.waitmask))
                        blackfin_dcache_invalidate_range(
                                (unsigned long)(&msg->call_struct.waitmask),
                                (unsigned long)(&msg->call_struct.waitmask));
                kfree(msg);
        }
        return 0;
}
EXPORT_SYMBOL_GPL(smp_call_function_single);

void smp_send_reschedule(int cpu)
{
        unsigned long flags;
        struct ipi_message_queue *msg_queue;
        struct ipi_message *msg;

        if (cpu_is_offline(cpu))
                return;

        msg = kmalloc(sizeof(*msg), GFP_ATOMIC);
        memset(msg, 0, sizeof(msg));
        INIT_LIST_HEAD(&msg->list);
        msg->type = BFIN_IPI_RESCHEDULE;

        msg_queue = &per_cpu(ipi_msg_queue, cpu);
        spin_lock_irqsave(&msg_queue->lock, flags);
        list_add_tail(&msg->list, &msg_queue->head);
        spin_unlock_irqrestore(&msg_queue->lock, flags);
        platform_send_ipi_cpu(cpu);

        return;
}

void smp_send_stop(void)
{
        unsigned int cpu;
        cpumask_t callmap;
        unsigned long flags;
        struct ipi_message_queue *msg_queue;
        struct ipi_message *msg;

        callmap = cpu_online_map;
        cpu_clear(smp_processor_id(), callmap);
        if (cpus_empty(callmap))
                return;

        msg = kmalloc(sizeof(*msg), GFP_ATOMIC);
        memset(msg, 0, sizeof(msg));
        INIT_LIST_HEAD(&msg->list);
        msg->type = BFIN_IPI_CPU_STOP;

        for_each_cpu_mask(cpu, callmap) {
                msg_queue = &per_cpu(ipi_msg_queue, cpu);
                spin_lock_irqsave(&msg_queue->lock, flags);
                list_add_tail(&msg->list, &msg_queue->head);
                spin_unlock_irqrestore(&msg_queue->lock, flags);
                platform_send_ipi_cpu(cpu);
        }
        return;
}

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

        idle = fork_idle(cpu);
        if (IS_ERR(idle)) {
                printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
                return PTR_ERR(idle);
        }

        secondary_stack = task_stack_page(idle) + THREAD_SIZE;
        smp_wmb();

        ret = platform_boot_secondary(cpu, idle);

        if (ret) {
                cpu_clear(cpu, cpu_present_map);
                printk(KERN_CRIT "CPU%u: processor failed to boot (%d)\n", cpu, ret);
                free_task(idle);
        } else
                cpu_set(cpu, cpu_online_map);

        secondary_stack = NULL;

        return ret;
}

static void __cpuinit setup_secondary(unsigned int cpu)
{
#if !defined(CONFIG_TICKSOURCE_GPTMR0)
        struct irq_desc *timer_desc;
#endif
        unsigned long ilat;

        bfin_write_IMASK(0);
        CSYNC();
        ilat = bfin_read_ILAT();
        CSYNC();
        bfin_write_ILAT(ilat);
        CSYNC();

        /* Enable interrupt levels IVG7-15. IARs have been already
         * programmed by the boot CPU.  */
        bfin_irq_flags |= IMASK_IVG15 |
            IMASK_IVG14 | IMASK_IVG13 | IMASK_IVG12 | IMASK_IVG11 |
            IMASK_IVG10 | IMASK_IVG9 | IMASK_IVG8 | IMASK_IVG7 | IMASK_IVGHW;

#if defined(CONFIG_TICKSOURCE_GPTMR0)
        /* Power down the core timer, just to play safe. */
        bfin_write_TCNTL(0);

        /* system timer0 has been setup by CoreA. */
#else
        timer_desc = irq_desc + IRQ_CORETMR;
        setup_core_timer();
        timer_desc->chip->enable(IRQ_CORETMR);
#endif
}

void __cpuinit secondary_start_kernel(void)
{
        unsigned int cpu = smp_processor_id();
        struct mm_struct *mm = &init_mm;

        if (_bfin_swrst & SWRST_DBL_FAULT_B) {
                printk(KERN_EMERG "CoreB Recovering from DOUBLE FAULT event\n");
#ifdef CONFIG_DEBUG_DOUBLEFAULT
                printk(KERN_EMERG " While handling exception (EXCAUSE = 0x%x) at %pF\n",
                        (int)init_saved_seqstat_coreb & SEQSTAT_EXCAUSE, init_saved_retx_coreb);
                printk(KERN_NOTICE "   DCPLB_FAULT_ADDR: %pF\n", init_saved_dcplb_fault_addr_coreb);
                printk(KERN_NOTICE "   ICPLB_FAULT_ADDR: %pF\n", init_saved_icplb_fault_addr_coreb);
#endif
                printk(KERN_NOTICE " The instruction at %pF caused a double exception\n",
                        init_retx_coreb);
        }

        /*
         * We want the D-cache to be enabled early, in case the atomic
         * support code emulates cache coherence (see
         * __ARCH_SYNC_CORE_DCACHE).
         */
        init_exception_vectors();

        bfin_setup_caches(cpu);

        local_irq_disable();

        /* Attach the new idle task to the global mm. */
        atomic_inc(&mm->mm_users);
        atomic_inc(&mm->mm_count);
        current->active_mm = mm;
        BUG_ON(current->mm);    /* Can't be, but better be safe than sorry. */

        preempt_disable();

        setup_secondary(cpu);

        local_irq_enable();

        platform_secondary_init(cpu);

        cpu_idle();
}

void __init smp_prepare_boot_cpu(void)
{
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
        platform_prepare_cpus(max_cpus);
        ipi_queue_init();
        platform_request_ipi(&ipi_handler);
}

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

        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);
}

void smp_icache_flush_range_others(unsigned long start, unsigned long end)
{
        smp_flush_data.start = start;
        smp_flush_data.end = end;

        if (smp_call_function(&ipi_flush_icache, &smp_flush_data, 0))
                printk(KERN_WARNING "SMP: failed to run I-cache flush request on other CPUs\n");
}
EXPORT_SYMBOL_GPL(smp_icache_flush_range_others);

#ifdef __ARCH_SYNC_CORE_ICACHE
void resync_core_icache(void)
{
        unsigned int cpu = get_cpu();
        blackfin_invalidate_entire_icache();
        ++per_cpu(cpu_data, cpu).icache_invld_count;
        put_cpu();
}
EXPORT_SYMBOL(resync_core_icache);
#endif

#ifdef __ARCH_SYNC_CORE_DCACHE
unsigned long barrier_mask __attribute__ ((__section__(".l2.bss")));

void resync_core_dcache(void)
{
        unsigned int cpu = get_cpu();
        blackfin_invalidate_entire_dcache();
        ++per_cpu(cpu_data, cpu).dcache_invld_count;
        put_cpu();
}
EXPORT_SYMBOL(resync_core_dcache);
#endif