WebSVN – HelenOS – Diff – /tags/0.2.0.1/kernel/genarch/src/mm/page_pt.c


/*
 * 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)];
}
 

Subversion Repositories HelenOS

(root)/tags/0.2.0.1/kernel/genarch/src/mm/page_pt.c – Rev 1965 → 1968

Rev 1965		Rev 1968
1	/*	1	/*
2	* Copyright (C) 2006 Jakub Jermar	2	* Copyright (C) 2006 Jakub Jermar
3	* All rights reserved.	3	* All rights reserved.
4	*	4	*
5	* Redistribution and use in source and binary forms, with or without	5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions	6	* modification, are permitted provided that the following conditions
7	* are met:	7	* are met:
8	*	8	*
9	* - Redistributions of source code must retain the above copyright	9	* - Redistributions of source code must retain the above copyright
10	* notice, this list of conditions and the following disclaimer.	10	* notice, this list of conditions and the following disclaimer.
11	* - Redistributions in binary form must reproduce the above copyright	11	* - Redistributions in binary form must reproduce the above copyright
12	* notice, this list of conditions and the following disclaimer in the	12	* notice, this list of conditions and the following disclaimer in the
13	* documentation and/or other materials provided with the distribution.	13	* documentation and/or other materials provided with the distribution.
14	* - The name of the author may not be used to endorse or promote products	14	* - The name of the author may not be used to endorse or promote products
15	* derived from this software without specific prior written permission.	15	* derived from this software without specific prior written permission.
16	*	16	*
17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR	17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES	18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.	19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,	20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT	21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,	22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY	23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT	24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF	25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27	*/	27	*/
28		28
29	/**	29	/**
30	* @file page_pt.c	30	* @file page_pt.c
31	* @brief Virtual Address Translation for hierarchical 4-level page tables.	31	* @brief Virtual Address Translation for hierarchical 4-level page tables.
32	*/	32	*/
33		33
34	#include <genarch/mm/page_pt.h>	34	#include <genarch/mm/page_pt.h>
35	#include <mm/page.h>	35	#include <mm/page.h>
36	#include <mm/frame.h>	36	#include <mm/frame.h>
37	#include <mm/as.h>	37	#include <mm/as.h>
38	#include <arch/mm/page.h>	38	#include <arch/mm/page.h>
39	#include <arch/mm/as.h>	39	#include <arch/mm/as.h>
40	#include <arch/types.h>	40	#include <arch/types.h>
41	#include <typedefs.h>	41	#include <typedefs.h>
42	#include <arch/asm.h>	42	#include <arch/asm.h>
43	#include <memstr.h>	43	#include <memstr.h>
44		44
45	static void pt_mapping_insert(as_t *as, __address page, __address frame, int flags);	45	static void pt_mapping_insert(as_t *as, __address page, __address frame, int flags);
46	static void pt_mapping_remove(as_t *as, __address page);	46	static void pt_mapping_remove(as_t *as, __address page);
47	static pte_t pt_mapping_find(as_t as, __address page);	47	static pte_t pt_mapping_find(as_t as, __address page);
48		48
49	page_mapping_operations_t pt_mapping_operations = {	49	page_mapping_operations_t pt_mapping_operations = {
50	.mapping_insert = pt_mapping_insert,	50	.mapping_insert = pt_mapping_insert,
51	.mapping_remove = pt_mapping_remove,	51	.mapping_remove = pt_mapping_remove,
52	.mapping_find = pt_mapping_find	52	.mapping_find = pt_mapping_find
53	};	53	};
54		54
55	/** Map page to frame using hierarchical page tables.	55	/** Map page to frame using hierarchical page tables.
56	*	56	*
57	* Map virtual address page to physical address frame	57	* Map virtual address page to physical address frame
58	* using flags.	58	* using flags.
59	*	59	*
60	* The page table must be locked and interrupts must be disabled.	60	* The page table must be locked and interrupts must be disabled.
61	*	61	*
62	* @param as Address space to wich page belongs.	62	* @param as Address space to wich page belongs.
63	* @param page Virtual address of the page to be mapped.	63	* @param page Virtual address of the page to be mapped.
64	* @param frame Physical address of memory frame to which the mapping is done.	64	* @param frame Physical address of memory frame to which the mapping is done.
65	* @param flags Flags to be used for mapping.	65	* @param flags Flags to be used for mapping.
66	*/	66	*/
67	void pt_mapping_insert(as_t *as, __address page, __address frame, int flags)	67	void pt_mapping_insert(as_t *as, __address page, __address frame, int flags)
68	{	68	{
69	pte_t ptl0, ptl1, ptl2, ptl3;	69	pte_t ptl0, ptl1, ptl2, ptl3;
70	__address newpt;	70	__address newpt;
71		71
72	ptl0 = (pte_t *) PA2KA((__address) as->page_table);	72	ptl0 = (pte_t *) PA2KA((__address) as->page_table);
73		73
74	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT) {	74	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT) {
75	newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));	75	newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));
76	memsetb(newpt, PAGE_SIZE, 0);	76	memsetb(newpt, PAGE_SIZE, 0);
77	SET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page), KA2PA(newpt));	77	SET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page), KA2PA(newpt));
78	SET_PTL1_FLAGS(ptl0, PTL0_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);	78	SET_PTL1_FLAGS(ptl0, PTL0_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);
79	}	79	}
80		80
81	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));	81	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
82		82
83	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT) {	83	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT) {
84	newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));	84	newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));
85	memsetb(newpt, PAGE_SIZE, 0);	85	memsetb(newpt, PAGE_SIZE, 0);
86	SET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page), KA2PA(newpt));	86	SET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page), KA2PA(newpt));
87	SET_PTL2_FLAGS(ptl1, PTL1_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);	87	SET_PTL2_FLAGS(ptl1, PTL1_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);
88	}	88	}
89		89
90	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));	90	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
91		91
92	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT) {	92	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT) {
93	newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));	93	newpt = PA2KA(PFN2ADDR(frame_alloc(ONE_FRAME, FRAME_KA)));
94	memsetb(newpt, PAGE_SIZE, 0);	94	memsetb(newpt, PAGE_SIZE, 0);
95	SET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page), KA2PA(newpt));	95	SET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page), KA2PA(newpt));
96	SET_PTL3_FLAGS(ptl2, PTL2_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);	96	SET_PTL3_FLAGS(ptl2, PTL2_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);
97	}	97	}
98		98
99	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));	99	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
100		100
101	SET_FRAME_ADDRESS(ptl3, PTL3_INDEX(page), frame);	101	SET_FRAME_ADDRESS(ptl3, PTL3_INDEX(page), frame);
102	SET_FRAME_FLAGS(ptl3, PTL3_INDEX(page), flags);	102	SET_FRAME_FLAGS(ptl3, PTL3_INDEX(page), flags);
103	}	103	}
104		104
105	/** Remove mapping of page from hierarchical page tables.	105	/** Remove mapping of page from hierarchical page tables.
106	*	106	*
107	* Remove any mapping of page within address space as.	107	* Remove any mapping of page within address space as.
108	* TLB shootdown should follow in order to make effects of	108	* TLB shootdown should follow in order to make effects of
109	* this call visible.	109	* this call visible.
110	*	110	*
111	* Empty page tables except PTL0 are freed.	111	* Empty page tables except PTL0 are freed.
112	*	112	*
113	* The page table must be locked and interrupts must be disabled.	113	* The page table must be locked and interrupts must be disabled.
114	*	114	*
115	* @param as Address space to wich page belongs.	115	* @param as Address space to wich page belongs.
116	* @param page Virtual address of the page to be demapped.	116	* @param page Virtual address of the page to be demapped.
117	*/	117	*/
118	void pt_mapping_remove(as_t *as, __address page)	118	void pt_mapping_remove(as_t *as, __address page)
119	{	119	{
120	pte_t ptl0, ptl1, ptl2, ptl3;	120	pte_t ptl0, ptl1, ptl2, ptl3;
121	bool empty = true;	121	bool empty = true;
122	int i;	122	int i;
123		123
124	/*	124	/*
125	* First, remove the mapping, if it exists.	125	* First, remove the mapping, if it exists.
126	*/	126	*/
127		127
128	ptl0 = (pte_t *) PA2KA((__address) as->page_table);	128	ptl0 = (pte_t *) PA2KA((__address) as->page_table);
129		129
130	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)	130	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)
131	return;	131	return;
132		132
133	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));	133	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
134		134
135	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)	135	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)
136	return;	136	return;
137		137
138	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));	138	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
139		139
140	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)	140	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)
141	return;	141	return;
142		142
143	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));	143	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
144		144
145	/* Destroy the mapping. Setting to PAGE_NOT_PRESENT is not sufficient. */	145	/* Destroy the mapping. Setting to PAGE_NOT_PRESENT is not sufficient. */
146	memsetb((__address) &ptl3[PTL3_INDEX(page)], sizeof(pte_t), 0);	146	memsetb((__address) &ptl3[PTL3_INDEX(page)], sizeof(pte_t), 0);
147		147
148	/*	148	/*
149	* Second, free all empty tables along the way from PTL3 down to PTL0.	149	* Second, free all empty tables along the way from PTL3 down to PTL0.
150	*/	150	*/
151		151
152	/* check PTL3 */	152	/* check PTL3 */
153	for (i = 0; i < PTL3_ENTRIES; i++) {	153	for (i = 0; i < PTL3_ENTRIES; i++) {
154	if (PTE_VALID(&ptl3[i])) {	154	if (PTE_VALID(&ptl3[i])) {
155	empty = false;	155	empty = false;
156	break;	156	break;
157	}	157	}
158	}	158	}
159	if (empty) {	159	if (empty) {
160	/*	160	/*
161	* PTL3 is empty.	161	* PTL3 is empty.
162	* Release the frame and remove PTL3 pointer from preceding table.	162	* Release the frame and remove PTL3 pointer from preceding table.
163	*/	163	*/
164	frame_free(ADDR2PFN(KA2PA((__address) ptl3)));	164	frame_free(ADDR2PFN(KA2PA((__address) ptl3)));
165	if (PTL2_ENTRIES)	165	if (PTL2_ENTRIES)
166	memsetb((__address) &ptl2[PTL2_INDEX(page)], sizeof(pte_t), 0);	166	memsetb((__address) &ptl2[PTL2_INDEX(page)], sizeof(pte_t), 0);
167	else if (PTL1_ENTRIES)	167	else if (PTL1_ENTRIES)
168	memsetb((__address) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);	168	memsetb((__address) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);
169	else	169	else
170	memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);	170	memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
171	} else {	171	} else {
172	/*	172	/*
173	* PTL3 is not empty.	173	* PTL3 is not empty.
174	* Therefore, there must be a path from PTL0 to PTL3 and	174	* Therefore, there must be a path from PTL0 to PTL3 and
175	* thus nothing to free in higher levels.	175	* thus nothing to free in higher levels.
176	*/	176	*/
177	return;	177	return;
178	}	178	}
179		179
180	/* check PTL2, empty is still true */	180	/* check PTL2, empty is still true */
181	if (PTL2_ENTRIES) {	181	if (PTL2_ENTRIES) {
182	for (i = 0; i < PTL2_ENTRIES; i++) {	182	for (i = 0; i < PTL2_ENTRIES; i++) {
183	if (PTE_VALID(&ptl2[i])) {	183	if (PTE_VALID(&ptl2[i])) {
184	empty = false;	184	empty = false;
185	break;	185	break;
186	}	186	}
187	}	187	}
188	if (empty) {	188	if (empty) {
189	/*	189	/*
190	* PTL2 is empty.	190	* PTL2 is empty.
191	* Release the frame and remove PTL2 pointer from preceding table.	191	* Release the frame and remove PTL2 pointer from preceding table.
192	*/	192	*/
193	frame_free(ADDR2PFN(KA2PA((__address) ptl2)));	193	frame_free(ADDR2PFN(KA2PA((__address) ptl2)));
194	if (PTL1_ENTRIES)	194	if (PTL1_ENTRIES)
195	memsetb((__address) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);	195	memsetb((__address) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);
196	else	196	else
197	memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);	197	memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
198	}	198	}
199	else {	199	else {
200	/*	200	/*
201	* PTL2 is not empty.	201	* PTL2 is not empty.
202	* Therefore, there must be a path from PTL0 to PTL2 and	202	* Therefore, there must be a path from PTL0 to PTL2 and
203	* thus nothing to free in higher levels.	203	* thus nothing to free in higher levels.
204	*/	204	*/
205	return;	205	return;
206	}	206	}
207	}	207	}
208		208
209	/* check PTL1, empty is still true */	209	/* check PTL1, empty is still true */
210	if (PTL1_ENTRIES) {	210	if (PTL1_ENTRIES) {
211	for (i = 0; i < PTL1_ENTRIES; i++) {	211	for (i = 0; i < PTL1_ENTRIES; i++) {
212	if (PTE_VALID(&ptl1[i])) {	212	if (PTE_VALID(&ptl1[i])) {
213	empty = false;	213	empty = false;
214	break;	214	break;
215	}	215	}
216	}	216	}
217	if (empty) {	217	if (empty) {
218	/*	218	/*
219	* PTL1 is empty.	219	* PTL1 is empty.
220	* Release the frame and remove PTL1 pointer from preceding table.	220	* Release the frame and remove PTL1 pointer from preceding table.
221	*/	221	*/
222	frame_free(ADDR2PFN(KA2PA((__address) ptl1)));	222	frame_free(ADDR2PFN(KA2PA((__address) ptl1)));
223	memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);	223	memsetb((__address) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
224	}	224	}
225	}	225	}
226		226
227	}	227	}
228		228
229	/** Find mapping for virtual page in hierarchical page tables.	229	/** Find mapping for virtual page in hierarchical page tables.
230	*	230	*
231	* Find mapping for virtual page.	231	* Find mapping for virtual page.
232	*	232	*
233	* The page table must be locked and interrupts must be disabled.	233	* The page table must be locked and interrupts must be disabled.
234	*	234	*
235	* @param as Address space to which page belongs.	235	* @param as Address space to which page belongs.
236	* @param page Virtual page.	236	* @param page Virtual page.
237	*	237	*
238	* @return NULL if there is no such mapping; entry from PTL3 describing the mapping otherwise.	238	* @return NULL if there is no such mapping; entry from PTL3 describing the mapping otherwise.
239	*/	239	*/
240	pte_t pt_mapping_find(as_t as, __address page)	240	pte_t pt_mapping_find(as_t as, __address page)
241	{	241	{
242	pte_t ptl0, ptl1, ptl2, ptl3;	242	pte_t ptl0, ptl1, ptl2, ptl3;
243		243
244	ptl0 = (pte_t *) PA2KA((__address) as->page_table);	244	ptl0 = (pte_t *) PA2KA((__address) as->page_table);
245		245
246	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)	246	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)
247	return NULL;	247	return NULL;
248		248
249	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));	249	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
250		250
251	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)	251	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)
252	return NULL;	252	return NULL;
253		253
254	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));	254	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
255		255
256	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)	256	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)
257	return NULL;	257	return NULL;
258		258
259	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));	259	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
260		260
261	return &ptl3[PTL3_INDEX(page)];	261	return &ptl3[PTL3_INDEX(page)];
262	}	262	}
263		263