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/*

 * Copyright (C) 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.

 */

/**

 * @file    page_pt.c

 * @brief   Virtual Address Translation for hierarchical 4-level page tables.

 */

#include <genarch/mm/page_pt.h>

#include <mm/page.h>

#include <mm/frame.h>

#include <mm/as.h>

#include <arch/mm/page.h>

#include <arch/mm/as.h>

#include <arch/types.h>

#include <typedefs.h>

#include <arch/asm.h>

#include <memstr.h>

static void pt_mapping_insert(as_t *as, __address page, __address frame, int flags);

static void pt_mapping_remove(as_t *as, __address page);

static pte_t *pt_mapping_find(as_t *as, __address page);

page_mapping_operations_t pt_mapping_operations = {

    .mapping_insert = pt_mapping_insert,

    .mapping_remove = pt_mapping_remove,

    .mapping_find = pt_mapping_find

};

/** Map page to frame using hierarchical page tables.

 *

 * Map virtual address page to physical address frame

 * using flags.

 *

 * The page table must be locked and interrupts must be disabled.

 *

 * @param as Address space to wich page belongs.

 * @param page Virtual address of the page to be mapped.

 * @param frame Physical address of memory frame to which the mapping is done.

 * @param flags Flags to be used for mapping.

 */

void pt_mapping_insert(as_t *as, __address page, __address frame, int flags)

{

    pte_t *ptl0, *ptl1, *ptl2, *ptl3;

    __address newpt;

    ptl0 = (pte_t *) PA2KA((__address) as->page_table);

    if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT) {

        newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));

        memsetb(newpt, PAGE_SIZE, 0);

        SET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page), KA2PA(newpt));

        SET_PTL1_FLAGS(ptl0, PTL0_INDEX(page), PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE | PAGE_WRITE);

    }

    ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));

    if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT) {

        newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));

        memsetb(newpt, PAGE_SIZE, 0);

        SET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page), KA2PA(newpt));

        SET_PTL2_FLAGS(ptl1, PTL1_INDEX(page), PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE | PAGE_WRITE);

    }

    ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));

    if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT) {

        newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));

        memsetb(newpt, PAGE_SIZE, 0);

        SET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page), KA2PA(newpt));

        SET_PTL3_FLAGS(ptl2, PTL2_INDEX(page), PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE | PAGE_WRITE);

    }

    ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));

    SET_FRAME_ADDRESS(ptl3, PTL3_INDEX(page), frame);

    SET_FRAME_FLAGS(ptl3, PTL3_INDEX(page), flags);

}

/** Remove mapping of page from hierarchical page tables.

 *

 * Remove any mapping of page within address space as.

 * TLB shootdown should follow in order to make effects of

 * this call visible.

 *

 * Empty page tables except PTL0 are freed.

 *

 * The page table must be locked and interrupts must be disabled.

 *

 * @param as Address space to wich page belongs.

 * @param page Virtual address of the page to be demapped.

 */

void pt_mapping_remove(as_t *as, __address page)

{

    pte_t *ptl0, *ptl1, *ptl2, *ptl3;

    bool empty = true;

    int i;

    /*

     * First, remove the mapping, if it exists.

     */

    ptl0 = (pte_t *) PA2KA((__address) as->page_table);

    if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)

        return;

    ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));

    if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)

        return;

    ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));

    if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)

        return;

    ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));

    /* Destroy the mapping. Setting to PAGE_NOT_PRESENT is not sufficient. */

    memsetb((__address) &ptl3[PTL3_INDEX(page)], sizeof(pte_t), 0);

    /*

     * Second, free all empty tables along the way from PTL3 down to PTL0.

     */

    /* check PTL3 */

    for (i = 0; i < PTL3_ENTRIES; i++) {

        if (PTE_VALID(&ptl3[i])) {

            empty = false;

            break;

        }

    }

    if (empty) {

        /*

         * PTL3 is empty.

         * Release the frame and remove PTL3 pointer from preceding table.

         */

        frame_free(ADDR2PFN(KA2PA((__address) ptl3)));

        if (PTL2_ENTRIES)

            memsetb((__address) &ptl2[PTL2_INDEX(page)], sizeof(pte_t), 0);

        else if (PTL1_ENTRIES)

            memsetb((__address) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);

        else

            memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);

    } else {

        /*

         * PTL3 is not empty.

         * Therefore, there must be a path from PTL0 to PTL3 and

         * thus nothing to free in higher levels.

         */

        return;

    }

    /* check PTL2, empty is still true */

    if (PTL2_ENTRIES) {

        for (i = 0; i < PTL2_ENTRIES; i++) {

            if (PTE_VALID(&ptl2[i])) {

                empty = false;

                break;

            }

        }

        if (empty) {

            /*

             * PTL2 is empty.

             * Release the frame and remove PTL2 pointer from preceding table.

             */

            frame_free(ADDR2PFN(KA2PA((__address) ptl2)));

            if (PTL1_ENTRIES)

                memsetb((__address) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);

            else

                memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);

        }

        else {

            /*

             * PTL2 is not empty.

             * Therefore, there must be a path from PTL0 to PTL2 and

             * thus nothing to free in higher levels.

             */

            return;

        }

    }

    /* check PTL1, empty is still true */

    if (PTL1_ENTRIES) {

        for (i = 0; i < PTL1_ENTRIES; i++) {

            if (PTE_VALID(&ptl1[i])) {

                empty = false;

                break;

            }

        }

        if (empty) {

            /*

             * PTL1 is empty.

             * Release the frame and remove PTL1 pointer from preceding table.

             */

            frame_free(ADDR2PFN(KA2PA((__address) ptl1)));

            memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);

        }

    }

}

/** Find mapping for virtual page in hierarchical page tables.

 *

 * Find mapping for virtual page.

 *

 * The page table must be locked and interrupts must be disabled.

 *

 * @param as Address space to which page belongs.

 * @param page Virtual page.

 *

 * @return NULL if there is no such mapping; entry from PTL3 describing the mapping otherwise.

 */

pte_t *pt_mapping_find(as_t *as, __address page)

{

    pte_t *ptl0, *ptl1, *ptl2, *ptl3;

    ptl0 = (pte_t *) PA2KA((__address) as->page_table);

    if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)

        return NULL;

    ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));

    if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)

        return NULL;

    ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));

    if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)

        return NULL;

    ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));

    return &ptl3[PTL3_INDEX(page)];

}