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/*

 * Copyright (C) 2001-2004 Jakub Jermar

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/**

 * @file    tlb.c

 * @brief   Generic TLB shootdown algorithm.

 *

 * The algorithm implemented here is based on the CMU TLB shootdown

 * algorithm and is further simplified (e.g. all CPUs receive all TLB

 * shootdown messages).

 */

#include <mm/tlb.h>

#include <mm/asid.h>

#include <arch/mm/tlb.h>

#include <smp/ipi.h>

#include <synch/spinlock.h>

#include <typedefs.h>

#include <atomic.h>

#include <arch/interrupt.h>

#include <config.h>

#include <arch.h>

#include <panic.h>

#include <debug.h>

/**

 * This lock is used for synchronisation between sender and

 * recipients of TLB shootdown message. It must be acquired

 * before CPU structure lock.

 */

SPINLOCK_INITIALIZE(tlblock);

void tlb_init(void)

{

    tlb_arch_init();

}

#ifdef CONFIG_SMP

/** Send TLB shootdown message.

 *

 * This function attempts to deliver TLB shootdown message

 * to all other processors.

 *

 * This function must be called with interrupts disabled.

 *

 * @param type Type describing scope of shootdown.

 * @param asid Address space, if required by type.

 * @param page Virtual page address, if required by type.

 * @param count Number of pages, if required by type.

 */

void tlb_shootdown_start(tlb_invalidate_type_t type, asid_t asid, __address page, count_t count)

{

    int i;

    CPU->tlb_active = 0;

    spinlock_lock(&tlblock);

    for (i = 0; i < config.cpu_count; i++) {

        cpu_t *cpu;

        if (i == CPU->id)

            continue;

        cpu = &cpus[i];

        spinlock_lock(&cpu->lock);

        if (cpu->tlb_messages_count == TLB_MESSAGE_QUEUE_LEN) {

            /*

             * The message queue is full.

             * Erase the queue and store one TLB_INVL_ALL message.

             */

            cpu->tlb_messages_count = 1;

            cpu->tlb_messages[0].type = TLB_INVL_ALL;

            cpu->tlb_messages[0].asid = ASID_INVALID;

            cpu->tlb_messages[0].page = 0;

            cpu->tlb_messages[0].count = 0;

        } else {

            /*

             * Enqueue the message.

             */

            cpu->tlb_messages[cpu->tlb_messages_count].type = type;

            cpu->tlb_messages[cpu->tlb_messages_count].asid = asid;

            cpu->tlb_messages[cpu->tlb_messages_count].page = page;

            cpu->tlb_messages[cpu->tlb_messages_count].count = count;

            cpu->tlb_messages_count++;

        }

        spinlock_unlock(&cpu->lock);

    }

    tlb_shootdown_ipi_send();

busy_wait: 

    for (i = 0; i < config.cpu_count; i++)

        if (cpus[i].tlb_active)

            goto busy_wait;

}

/** Finish TLB shootdown sequence. */

void tlb_shootdown_finalize(void)

{

    spinlock_unlock(&tlblock);

    CPU->tlb_active = 1;

}

void tlb_shootdown_ipi_send(void)

{

    ipi_broadcast(VECTOR_TLB_SHOOTDOWN_IPI);

}

/** Receive TLB shootdown message. */

void tlb_shootdown_ipi_recv(void)

{

    tlb_invalidate_type_t type;

    asid_t asid;

    __address page;

    count_t count;

    int i;

    ASSERT(CPU);

    CPU->tlb_active = 0;

    spinlock_lock(&tlblock);

    spinlock_unlock(&tlblock);

    spinlock_lock(&CPU->lock);

    ASSERT(CPU->tlb_messages_count <= TLB_MESSAGE_QUEUE_LEN);

    for (i = 0; i < CPU->tlb_messages_count; CPU->tlb_messages_count--) {

        type = CPU->tlb_messages[i].type;

        asid = CPU->tlb_messages[i].asid;

        page = CPU->tlb_messages[i].page;

        count = CPU->tlb_messages[i].count;

        switch (type) {

            case TLB_INVL_ALL:

            tlb_invalidate_all();

            break;

            case TLB_INVL_ASID:

            tlb_invalidate_asid(asid);

            break;

            case TLB_INVL_PAGES:

                ASSERT(count);

            tlb_invalidate_pages(asid, page, count);

            break;

            default:

            panic("unknown type (%d)\n", type);

            break;

        }

        if (type == TLB_INVL_ALL)

            break;

    }

    spinlock_unlock(&CPU->lock);

    CPU->tlb_active = 1;

}

#endif /* CONFIG_SMP */