Subversion Repositories HelenOS-historic

/*

 * Copyright (C) 2001-2006 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.

 */

/*

 * This file contains address space manipulation functions.

 * Roughly speaking, this is a higher-level client of

 * Virtual Address Translation (VAT) subsystem.

 */

#include <mm/as.h>

#include <arch/mm/as.h>

#include <mm/page.h>

#include <mm/frame.h>

#include <mm/slab.h>

#include <mm/tlb.h>

#include <arch/mm/page.h>

#include <genarch/mm/page_pt.h>

#include <mm/asid.h>

#include <arch/mm/asid.h>

#include <arch/types.h>

#include <typedefs.h>

#include <synch/spinlock.h>

#include <config.h>

#include <adt/list.h>

#include <panic.h>

#include <arch/asm.h>

#include <debug.h>

#include <memstr.h>

#include <arch.h>

#include <print.h>

as_operations_t *as_operations = NULL;

/** Address space lock. It protects inactive_as_with_asid_head. */

SPINLOCK_INITIALIZE(as_lock);

/**

 * This list contains address spaces that are not active on any

 * processor and that have valid ASID.

 */

LIST_INITIALIZE(inactive_as_with_asid_head);

/** Kernel address space. */

as_t *AS_KERNEL = NULL;

static int get_area_flags(as_area_t *a);

/** Initialize address space subsystem. */

void as_init(void)

{

    as_arch_init();

    AS_KERNEL = as_create(FLAG_AS_KERNEL);

        if (!AS_KERNEL)

                panic("can't create kernel address space\n");

}

/** Create address space.

 *

 * @param flags Flags that influence way in wich the address space is created.

 */

as_t *as_create(int flags)

{

    as_t *as;

    as = (as_t *) malloc(sizeof(as_t), 0);

    link_initialize(&as->inactive_as_with_asid_link);

    spinlock_initialize(&as->lock, "as_lock");

    list_initialize(&as->as_area_head);

    if (flags & FLAG_AS_KERNEL)

        as->asid = ASID_KERNEL;

    else

        as->asid = ASID_INVALID;

    as->refcount = 0;

    as->page_table = page_table_create(flags);

    return as;

}

/** Free Adress space */

void as_free(as_t *as)

{

    ASSERT(as->refcount == 0);

    /* TODO: free as_areas and other resources held by as */

    /* TODO: free page table */

    free(as);

}

/** Create address space area of common attributes.

 *

 * The created address space area is added to the target address space.

 *

 * @param as Target address space.

 * @param type Type of area.

 * @param size Size of area in multiples of PAGE_SIZE.

 * @param base Base address of area.

 *

 * @return Address space area on success or NULL on failure.

 */

as_area_t *as_area_create(as_t *as, as_area_type_t type, size_t size, __address base)

{

    ipl_t ipl;

    as_area_t *a;

    if (base % PAGE_SIZE)

        panic("addr not aligned to a page boundary");

    ipl = interrupts_disable();

    spinlock_lock(&as->lock);

    /*

     * TODO: test as_area which is to be created doesn't overlap with an existing one.

     */

    a = (as_area_t *) malloc(sizeof(as_area_t), 0);

    spinlock_initialize(&a->lock, "as_area_lock");

    link_initialize(&a->link);         

    a->type = type;

    a->size = size;

    a->base = base;

    list_append(&a->link, &as->as_area_head);

    spinlock_unlock(&as->lock);

    interrupts_restore(ipl);

    return a;

}

/** Initialize mapping for one page of address space.

 *

 * This functions maps 'page' to 'frame' according

 * to attributes of the address space area to

 * wich 'page' belongs.

 *

 * @param as Target address space.

 * @param page Virtual page within the area.

 * @param frame Physical frame to which page will be mapped.

 */

void as_set_mapping(as_t *as, __address page, __address frame)

{

    as_area_t *a, *area = NULL;

    link_t *cur;

    ipl_t ipl;

    ipl = interrupts_disable();

    spinlock_lock(&as->lock);

    /*

     * First, try locate an area.

     */

    for (cur = as->as_area_head.next; cur != &as->as_area_head; cur = cur->next) {

        a = list_get_instance(cur, as_area_t, link);

        spinlock_lock(&a->lock);

        if ((page >= a->base) && (page < a->base + a->size * PAGE_SIZE)) {

            area = a;

            break;

        }

        spinlock_unlock(&a->lock);

    }

    if (!area) {

        panic("page not part of any as_area\n");

    }

    /*

     * Note: area->lock is held.

     */

    page_mapping_insert(as, page, frame, get_area_flags(area));

    spinlock_unlock(&area->lock);

    spinlock_unlock(&as->lock);

    interrupts_restore(ipl);

}

/** Handle page fault within the current address space.

 *

 * This is the high-level page fault handler.

 * Interrupts are assumed disabled.

 *

 * @param page Faulting page.

 *

 * @return 0 on page fault, 1 on success.

 */

int as_page_fault(__address page)

{

    link_t *cur;

    as_area_t *a, *area = NULL;

    __address frame;

    ASSERT(AS);

    spinlock_lock(&AS->lock);

    /*

     * Search this areas of this address space for presence of 'page'.

     */

    for (cur = AS->as_area_head.next; cur != &AS->as_area_head; cur = cur->next) {

        a = list_get_instance(cur, as_area_t, link);

        spinlock_lock(&a->lock);

        if ((page >= a->base) && (page < a->base + a->size * PAGE_SIZE)) {

            /*

             * We found the area containing 'page'.

             * TODO: access checking

             */

            area = a;

            break;

        }

        spinlock_unlock(&a->lock);

    }

    if (!area) {

        /*

         * No area contained mapping for 'page'.

         * Signal page fault to low-level handler.

         */

        spinlock_unlock(&AS->lock);

        return 0;

    }

    /*

     * Note: area->lock is held.

     */

    /*

     * In general, there can be several reasons that

     * can have caused this fault.

     *

     * - non-existent mapping: the area is a scratch

     *   area (e.g. stack) and so far has not been

     *   allocated a frame for the faulting page

     *

     * - non-present mapping: another possibility,

     *   currently not implemented, would be frame

     *   reuse; when this becomes a possibility,

     *   do not forget to distinguish between

     *   the different causes

     */

    frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));

    memsetb(PA2KA(frame), FRAME_SIZE, 0);

    /*

     * Map 'page' to 'frame'.

     * Note that TLB shootdown is not attempted as only new information is being

     * inserted into page tables.

     */

    page_mapping_insert(AS, page, frame, get_area_flags(area));

    spinlock_unlock(&area->lock);

    spinlock_unlock(&AS->lock);

    return 1;

}

/** Switch address spaces.

 *

 * @param old Old address space or NULL.

 * @param new New address space.

 */

void as_switch(as_t *old, as_t *new)

{

    ipl_t ipl;

    bool needs_asid = false;

    ipl = interrupts_disable();

    spinlock_lock(&as_lock);

    /*

     * First, take care of the old address space.

     */

    if (old) {

        spinlock_lock(&old->lock);

        ASSERT(old->refcount);

        if((--old->refcount == 0) && (old != AS_KERNEL)) {

            /*

             * The old address space is no longer active on

             * any processor. It can be appended to the

             * list of inactive address spaces with assigned

             * ASID.

             */

             ASSERT(old->asid != ASID_INVALID);

             list_append(&old->inactive_as_with_asid_link, &inactive_as_with_asid_head);

        }

        spinlock_unlock(&old->lock);

    }

    /*

     * Second, prepare the new address space.

     */

    spinlock_lock(&new->lock);

    if ((new->refcount++ == 0) && (new != AS_KERNEL)) {

        if (new->asid != ASID_INVALID)

            list_remove(&new->inactive_as_with_asid_link);

        else

            needs_asid = true;  /* defer call to asid_get() until new->lock is released */

    }

    SET_PTL0_ADDRESS(new->page_table);

    spinlock_unlock(&new->lock);

    if (needs_asid) {

        /*

         * Allocation of new ASID was deferred

         * until now in order to avoid deadlock.

         */

        asid_t asid;

        asid = asid_get();

        spinlock_lock(&new->lock);

        new->asid = asid;

        spinlock_unlock(&new->lock);

    }

    spinlock_unlock(&as_lock);

    interrupts_restore(ipl);

    /*

     * Perform architecture-specific steps.

     * (e.g. write ASID to hardware register etc.)

     */

    as_install_arch(new);

    AS = new;

}

/** Compute flags for virtual address translation subsytem.

 *

 * The address space area must be locked.

 * Interrupts must be disabled.

 *

 * @param a Address space area.

 *

 * @return Flags to be used in page_mapping_insert().

 */

int get_area_flags(as_area_t *a)

{

    int flags;

    switch (a->type) {

        case AS_AREA_TEXT:

            flags = PAGE_EXEC | PAGE_READ | PAGE_USER | PAGE_PRESENT | PAGE_CACHEABLE;

            break;

        case AS_AREA_DATA:

        case AS_AREA_STACK:

            flags = PAGE_READ | PAGE_WRITE | PAGE_USER | PAGE_PRESENT | PAGE_CACHEABLE;

            break;

        default:

            panic("unexpected as_area_type_t %d", a->type);

    }

    return flags;

}

/** Create page table.

 *

 * Depending on architecture, create either address space

 * private or global page table.

 *

 * @param flags Flags saying whether the page table is for kernel address space.

 *

 * @return First entry of the page table.

 */

pte_t *page_table_create(int flags)

{

        ASSERT(as_operations);

        ASSERT(as_operations->page_table_create);

        return as_operations->page_table_create(flags);

}