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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)];

}