WebSVN – HelenOS – Diff – /trunk/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.
 */
 
/** @addtogroup genarchmm
 * @{
 */
 
/**
 * @file
 * @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 <arch/asm.h>
#include <memstr.h>
 
static void pt_mapping_insert(as_t *as, uintptr_t page, uintptr_t frame, int flags);
static void pt_mapping_remove(as_t *as, uintptr_t page);
static pte_t *pt_mapping_find(as_t *as, uintptr_t 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, uintptr_t page, uintptr_t frame, int flags)
{
    pte_t *ptl0, *ptl1, *ptl2, *ptl3;
    pte_t *newpt;
 
    ptl0 = (pte_t *) PA2KA((uintptr_t) as->page_table);
 
    if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT) {
        newpt = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);
        memsetb((uintptr_t)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 = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);
        memsetb((uintptr_t)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 = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);
        memsetb((uintptr_t)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, uintptr_t page)
{
    pte_t *ptl0, *ptl1, *ptl2, *ptl3;
    bool empty = true;
    int i;
 
    /*
     * First, remove the mapping, if it exists.
     */
 
    ptl0 = (pte_t *) PA2KA((uintptr_t) 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((uintptr_t) &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(KA2PA((uintptr_t) ptl3));
        if (PTL2_ENTRIES)
            memsetb((uintptr_t) &ptl2[PTL2_INDEX(page)], sizeof(pte_t), 0);
        else if (PTL1_ENTRIES)
            memsetb((uintptr_t) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);
        else
            memsetb((uintptr_t) &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(KA2PA((uintptr_t) ptl2));
            if (PTL1_ENTRIES)
                memsetb((uintptr_t) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);
            else
                memsetb((uintptr_t) &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(KA2PA((uintptr_t) ptl1));
            memsetb((uintptr_t) &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, uintptr_t page)
{
    pte_t *ptl0, *ptl1, *ptl2, *ptl3;
 
    ptl0 = (pte_t *) PA2KA((uintptr_t) 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)/trunk/kernel/genarch/src/mm/page_pt.c – Rev 2071 → 2089

Rev 2071		Rev 2089
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	/** @addtogroup genarchmm	29	/** @addtogroup genarchmm
30	* @{	30	* @{
31	*/	31	*/
32		32
33	/**	33	/**
34	* @file	34	* @file
35	* @brief Virtual Address Translation for hierarchical 4-level page tables.	35	* @brief Virtual Address Translation for hierarchical 4-level page tables.
36	*/	36	*/
37		37
38	#include <genarch/mm/page_pt.h>	38	#include <genarch/mm/page_pt.h>
39	#include <mm/page.h>	39	#include <mm/page.h>
40	#include <mm/frame.h>	40	#include <mm/frame.h>
41	#include <mm/as.h>	41	#include <mm/as.h>
42	#include <arch/mm/page.h>	42	#include <arch/mm/page.h>
43	#include <arch/mm/as.h>	43	#include <arch/mm/as.h>
44	#include <arch/types.h>	44	#include <arch/types.h>
45	#include <typedefs.h>	-
46	#include <arch/asm.h>	45	#include <arch/asm.h>
47	#include <memstr.h>	46	#include <memstr.h>
48		47
49	static void pt_mapping_insert(as_t *as, uintptr_t page, uintptr_t frame, int flags);	48	static void pt_mapping_insert(as_t *as, uintptr_t page, uintptr_t frame, int flags);
50	static void pt_mapping_remove(as_t *as, uintptr_t page);	49	static void pt_mapping_remove(as_t *as, uintptr_t page);
51	static pte_t pt_mapping_find(as_t as, uintptr_t page);	50	static pte_t pt_mapping_find(as_t as, uintptr_t page);
52		51
53	page_mapping_operations_t pt_mapping_operations = {	52	page_mapping_operations_t pt_mapping_operations = {
54	.mapping_insert = pt_mapping_insert,	53	.mapping_insert = pt_mapping_insert,
55	.mapping_remove = pt_mapping_remove,	54	.mapping_remove = pt_mapping_remove,
56	.mapping_find = pt_mapping_find	55	.mapping_find = pt_mapping_find
57	};	56	};
58		57
59	/** Map page to frame using hierarchical page tables.	58	/** Map page to frame using hierarchical page tables.
60	*	59	*
61	* Map virtual address page to physical address frame	60	* Map virtual address page to physical address frame
62	* using flags.	61	* using flags.
63	*	62	*
64	* The page table must be locked and interrupts must be disabled.	63	* The page table must be locked and interrupts must be disabled.
65	*	64	*
66	* @param as Address space to wich page belongs.	65	* @param as Address space to wich page belongs.
67	* @param page Virtual address of the page to be mapped.	66	* @param page Virtual address of the page to be mapped.
68	* @param frame Physical address of memory frame to which the mapping is done.	67	* @param frame Physical address of memory frame to which the mapping is done.
69	* @param flags Flags to be used for mapping.	68	* @param flags Flags to be used for mapping.
70	*/	69	*/
71	void pt_mapping_insert(as_t *as, uintptr_t page, uintptr_t frame, int flags)	70	void pt_mapping_insert(as_t *as, uintptr_t page, uintptr_t frame, int flags)
72	{	71	{
73	pte_t ptl0, ptl1, ptl2, ptl3;	72	pte_t ptl0, ptl1, ptl2, ptl3;
74	pte_t *newpt;	73	pte_t *newpt;
75		74
76	ptl0 = (pte_t *) PA2KA((uintptr_t) as->page_table);	75	ptl0 = (pte_t *) PA2KA((uintptr_t) as->page_table);
77		76
78	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT) {	77	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT) {
79	newpt = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);	78	newpt = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);
80	memsetb((uintptr_t)newpt, PAGE_SIZE, 0);	79	memsetb((uintptr_t)newpt, PAGE_SIZE, 0);
81	SET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page), KA2PA(newpt));	80	SET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page), KA2PA(newpt));
82	SET_PTL1_FLAGS(ptl0, PTL0_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);	81	SET_PTL1_FLAGS(ptl0, PTL0_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);
83	}	82	}
84		83
85	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));	84	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
86		85
87	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT) {	86	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT) {
88	newpt = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);	87	newpt = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);
89	memsetb((uintptr_t)newpt, PAGE_SIZE, 0);	88	memsetb((uintptr_t)newpt, PAGE_SIZE, 0);
90	SET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page), KA2PA(newpt));	89	SET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page), KA2PA(newpt));
91	SET_PTL2_FLAGS(ptl1, PTL1_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);	90	SET_PTL2_FLAGS(ptl1, PTL1_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);
92	}	91	}
93		92
94	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));	93	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
95		94
96	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT) {	95	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT) {
97	newpt = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);	96	newpt = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);
98	memsetb((uintptr_t)newpt, PAGE_SIZE, 0);	97	memsetb((uintptr_t)newpt, PAGE_SIZE, 0);
99	SET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page), KA2PA(newpt));	98	SET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page), KA2PA(newpt));
100	SET_PTL3_FLAGS(ptl2, PTL2_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);	99	SET_PTL3_FLAGS(ptl2, PTL2_INDEX(page), PAGE_PRESENT \| PAGE_USER \| PAGE_EXEC \| PAGE_CACHEABLE \| PAGE_WRITE);
101	}	100	}
102		101
103	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));	102	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
104		103
105	SET_FRAME_ADDRESS(ptl3, PTL3_INDEX(page), frame);	104	SET_FRAME_ADDRESS(ptl3, PTL3_INDEX(page), frame);
106	SET_FRAME_FLAGS(ptl3, PTL3_INDEX(page), flags);	105	SET_FRAME_FLAGS(ptl3, PTL3_INDEX(page), flags);
107	}	106	}
108		107
109	/** Remove mapping of page from hierarchical page tables.	108	/** Remove mapping of page from hierarchical page tables.
110	*	109	*
111	* Remove any mapping of page within address space as.	110	* Remove any mapping of page within address space as.
112	* TLB shootdown should follow in order to make effects of	111	* TLB shootdown should follow in order to make effects of
113	* this call visible.	112	* this call visible.
114	*	113	*
115	* Empty page tables except PTL0 are freed.	114	* Empty page tables except PTL0 are freed.
116	*	115	*
117	* The page table must be locked and interrupts must be disabled.	116	* The page table must be locked and interrupts must be disabled.
118	*	117	*
119	* @param as Address space to wich page belongs.	118	* @param as Address space to wich page belongs.
120	* @param page Virtual address of the page to be demapped.	119	* @param page Virtual address of the page to be demapped.
121	*/	120	*/
122	void pt_mapping_remove(as_t *as, uintptr_t page)	121	void pt_mapping_remove(as_t *as, uintptr_t page)
123	{	122	{
124	pte_t ptl0, ptl1, ptl2, ptl3;	123	pte_t ptl0, ptl1, ptl2, ptl3;
125	bool empty = true;	124	bool empty = true;
126	int i;	125	int i;
127		126
128	/*	127	/*
129	* First, remove the mapping, if it exists.	128	* First, remove the mapping, if it exists.
130	*/	129	*/
131		130
132	ptl0 = (pte_t *) PA2KA((uintptr_t) as->page_table);	131	ptl0 = (pte_t *) PA2KA((uintptr_t) as->page_table);
133		132
134	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)	133	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)
135	return;	134	return;
136		135
137	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));	136	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
138		137
139	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)	138	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)
140	return;	139	return;
141		140
142	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));	141	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
143		142
144	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)	143	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)
145	return;	144	return;
146		145
147	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));	146	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
148		147
149	/* Destroy the mapping. Setting to PAGE_NOT_PRESENT is not sufficient. */	148	/* Destroy the mapping. Setting to PAGE_NOT_PRESENT is not sufficient. */
150	memsetb((uintptr_t) &ptl3[PTL3_INDEX(page)], sizeof(pte_t), 0);	149	memsetb((uintptr_t) &ptl3[PTL3_INDEX(page)], sizeof(pte_t), 0);
151		150
152	/*	151	/*
153	* Second, free all empty tables along the way from PTL3 down to PTL0.	152	* Second, free all empty tables along the way from PTL3 down to PTL0.
154	*/	153	*/
155		154
156	/* check PTL3 */	155	/* check PTL3 */
157	for (i = 0; i < PTL3_ENTRIES; i++) {	156	for (i = 0; i < PTL3_ENTRIES; i++) {
158	if (PTE_VALID(&ptl3[i])) {	157	if (PTE_VALID(&ptl3[i])) {
159	empty = false;	158	empty = false;
160	break;	159	break;
161	}	160	}
162	}	161	}
163	if (empty) {	162	if (empty) {
164	/*	163	/*
165	* PTL3 is empty.	164	* PTL3 is empty.
166	* Release the frame and remove PTL3 pointer from preceding table.	165	* Release the frame and remove PTL3 pointer from preceding table.
167	*/	166	*/
168	frame_free(KA2PA((uintptr_t) ptl3));	167	frame_free(KA2PA((uintptr_t) ptl3));
169	if (PTL2_ENTRIES)	168	if (PTL2_ENTRIES)
170	memsetb((uintptr_t) &ptl2[PTL2_INDEX(page)], sizeof(pte_t), 0);	169	memsetb((uintptr_t) &ptl2[PTL2_INDEX(page)], sizeof(pte_t), 0);
171	else if (PTL1_ENTRIES)	170	else if (PTL1_ENTRIES)
172	memsetb((uintptr_t) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);	171	memsetb((uintptr_t) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);
173	else	172	else
174	memsetb((uintptr_t) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);	173	memsetb((uintptr_t) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
175	} else {	174	} else {
176	/*	175	/*
177	* PTL3 is not empty.	176	* PTL3 is not empty.
178	* Therefore, there must be a path from PTL0 to PTL3 and	177	* Therefore, there must be a path from PTL0 to PTL3 and
179	* thus nothing to free in higher levels.	178	* thus nothing to free in higher levels.
180	*/	179	*/
181	return;	180	return;
182	}	181	}
183		182
184	/* check PTL2, empty is still true */	183	/* check PTL2, empty is still true */
185	if (PTL2_ENTRIES) {	184	if (PTL2_ENTRIES) {
186	for (i = 0; i < PTL2_ENTRIES; i++) {	185	for (i = 0; i < PTL2_ENTRIES; i++) {
187	if (PTE_VALID(&ptl2[i])) {	186	if (PTE_VALID(&ptl2[i])) {
188	empty = false;	187	empty = false;
189	break;	188	break;
190	}	189	}
191	}	190	}
192	if (empty) {	191	if (empty) {
193	/*	192	/*
194	* PTL2 is empty.	193	* PTL2 is empty.
195	* Release the frame and remove PTL2 pointer from preceding table.	194	* Release the frame and remove PTL2 pointer from preceding table.
196	*/	195	*/
197	frame_free(KA2PA((uintptr_t) ptl2));	196	frame_free(KA2PA((uintptr_t) ptl2));
198	if (PTL1_ENTRIES)	197	if (PTL1_ENTRIES)
199	memsetb((uintptr_t) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);	198	memsetb((uintptr_t) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);
200	else	199	else
201	memsetb((uintptr_t) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);	200	memsetb((uintptr_t) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
202	}	201	}
203	else {	202	else {
204	/*	203	/*
205	* PTL2 is not empty.	204	* PTL2 is not empty.
206	* Therefore, there must be a path from PTL0 to PTL2 and	205	* Therefore, there must be a path from PTL0 to PTL2 and
207	* thus nothing to free in higher levels.	206	* thus nothing to free in higher levels.
208	*/	207	*/
209	return;	208	return;
210	}	209	}
211	}	210	}
212		211
213	/* check PTL1, empty is still true */	212	/* check PTL1, empty is still true */
214	if (PTL1_ENTRIES) {	213	if (PTL1_ENTRIES) {
215	for (i = 0; i < PTL1_ENTRIES; i++) {	214	for (i = 0; i < PTL1_ENTRIES; i++) {
216	if (PTE_VALID(&ptl1[i])) {	215	if (PTE_VALID(&ptl1[i])) {
217	empty = false;	216	empty = false;
218	break;	217	break;
219	}	218	}
220	}	219	}
221	if (empty) {	220	if (empty) {
222	/*	221	/*
223	* PTL1 is empty.	222	* PTL1 is empty.
224	* Release the frame and remove PTL1 pointer from preceding table.	223	* Release the frame and remove PTL1 pointer from preceding table.
225	*/	224	*/
226	frame_free(KA2PA((uintptr_t) ptl1));	225	frame_free(KA2PA((uintptr_t) ptl1));
227	memsetb((uintptr_t) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);	226	memsetb((uintptr_t) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
228	}	227	}
229	}	228	}
230		229
231	}	230	}
232		231
233	/** Find mapping for virtual page in hierarchical page tables.	232	/** Find mapping for virtual page in hierarchical page tables.
234	*	233	*
235	* Find mapping for virtual page.	234	* Find mapping for virtual page.
236	*	235	*
237	* The page table must be locked and interrupts must be disabled.	236	* The page table must be locked and interrupts must be disabled.
238	*	237	*
239	* @param as Address space to which page belongs.	238	* @param as Address space to which page belongs.
240	* @param page Virtual page.	239	* @param page Virtual page.
241	*	240	*
242	* @return NULL if there is no such mapping; entry from PTL3 describing the mapping otherwise.	241	* @return NULL if there is no such mapping; entry from PTL3 describing the mapping otherwise.
243	*/	242	*/
244	pte_t pt_mapping_find(as_t as, uintptr_t page)	243	pte_t pt_mapping_find(as_t as, uintptr_t page)
245	{	244	{
246	pte_t ptl0, ptl1, ptl2, ptl3;	245	pte_t ptl0, ptl1, ptl2, ptl3;
247		246
248	ptl0 = (pte_t *) PA2KA((uintptr_t) as->page_table);	247	ptl0 = (pte_t *) PA2KA((uintptr_t) as->page_table);
249		248
250	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)	249	if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)
251	return NULL;	250	return NULL;
252		251
253	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));	252	ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
254		253
255	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)	254	if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)
256	return NULL;	255	return NULL;
257		256
258	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));	257	ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
259		258
260	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)	259	if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)
261	return NULL;	260	return NULL;
262		261
263	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));	262	ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
264		263
265	return &ptl3[PTL3_INDEX(page)];	264	return &ptl3[PTL3_INDEX(page)];
266	}	265	}
267		266
268	/** @}	267	/** @}
269	*/	268	*/
270		269