WebSVN – HelenOS-historic – Diff – /kernel/trunk/genarch/src/mm/page_ht.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.
 */
 
#include <genarch/mm/page_ht.h>
#include <mm/page.h>
#include <arch/mm/page.h>
#include <mm/frame.h>
#include <mm/slab.h>
#include <mm/as.h>
#include <arch/mm/asid.h>
#include <arch/types.h>
#include <typedefs.h>
#include <arch/asm.h>
#include <synch/spinlock.h>
#include <arch.h>
#include <debug.h>
#include <memstr.h>
#include <adt/hash_table.h>
#include <align.h>
 
static index_t hash(__native key[]);
static bool compare(__native key[], count_t keys, link_t *item);
static void remove_callback(link_t *item);
 
static void ht_mapping_insert(as_t *as, __address page, __address frame, int flags);
static void ht_mapping_remove(as_t *as, __address page);
static pte_t *ht_mapping_find(as_t *as, __address page);
 
/**
 * This lock protects the page hash table. It must be acquired
 * after address space lock and after any address space area
 * locks.
 */
SPINLOCK_INITIALIZE(page_ht_lock);
 
/**
 * Page hash table.
 * The page hash table may be accessed only when page_ht_lock is held.
 */
hash_table_t page_ht;
 
/** Hash table operations for page hash table. */
hash_table_operations_t ht_operations = {
    .hash = hash,
    .compare = compare,
    .remove_callback = remove_callback
};
 
/** Page mapping operations for page hash table architectures. */
page_mapping_operations_t ht_mapping_operations = {
    .mapping_insert = ht_mapping_insert,
    .mapping_remove = ht_mapping_remove,
    .mapping_find = ht_mapping_find
};
 
/** Compute page hash table index.
 *
 * @param key Array of two keys (i.e. page and address space).
 *
 * @return Index into page hash table.
 */
index_t hash(__native key[])
{
    as_t *as = (as_t *) key[KEY_AS];
    __address page = (__address) key[KEY_PAGE];
    index_t index;
   
    /*
     * Virtual page addresses have roughly the same probability
     * of occurring. Least significant bits of VPN compose the
     * hash index.
     */
    index = ((page >> PAGE_WIDTH) & (PAGE_HT_ENTRIES-1));
   
    /*
     * Address space structures are likely to be allocated from
     * similar addresses. Least significant bits compose the
     * hash index.
     */
    index |= ((__native) as) & (PAGE_HT_ENTRIES-1);
   
    return index;
}
 
/** Compare page hash table item with page and/or address space.
 *
 * @param key Array of one or two keys (i.e. page and/or address space).
 * @param keys Number of keys passed.
 * @param item Item to compare the keys with.
 *
 * @return true on match, false otherwise.
 */
bool compare(__native key[], count_t keys, link_t *item)
{
    pte_t *t;
 
    ASSERT(item);
    ASSERT((keys > 0) && (keys <= PAGE_HT_KEYS));
 
    /*
     * Convert item to PTE.
     */
    t = hash_table_get_instance(item, pte_t, link);
 
    if (keys == PAGE_HT_KEYS) {
        return (key[KEY_AS] == (__address) t->as) && (key[KEY_PAGE] == t->page);
    } else {
        return (key[KEY_AS] == (__address) t->as);
    }
}
 
/** Callback on page hash table item removal.
 *
 * @param item Page hash table item being removed.
 */
void remove_callback(link_t *item)
{
    pte_t *t;
 
    ASSERT(item);
 
    /*
     * Convert item to PTE.
     */
    t = hash_table_get_instance(item, pte_t, link);
 
    free(t);
}
 
/** Map page to frame using page hash table.
 *
 * 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 which 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 ht_mapping_insert(as_t *as, __address page, __address frame, int flags)
{
    pte_t *t;
    __native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
   
 
 
    if (!hash_table_find(&page_ht, key)) {
        t = (pte_t *) malloc(sizeof(pte_t), FRAME_ATOMIC);
        ASSERT(t != NULL);
 
        t->g = (flags & PAGE_GLOBAL) != 0;
        t->x = (flags & PAGE_EXEC) != 0;
        t->w = (flags & PAGE_WRITE) != 0;
        t->k = !(flags & PAGE_USER);
        t->c = (flags & PAGE_CACHEABLE) != 0;
        t->p = !(flags & PAGE_NOT_PRESENT);
 
        t->as = as;
        t->page = page;
        t->frame = frame;
 
        hash_table_insert(&page_ht, key, &t->link);
    }
 
 
}
 
/** Remove mapping of page from page hash table.
 *
 * Remove any mapping of 'page' within address space 'as'.
 * TLB shootdown should follow in order to make effects of
 * this call visible.
 *
 * 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 ht_mapping_remove(as_t *as, __address page)
{
    __native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
   
 
 
    /*
     * Note that removed PTE's will be freed
     * by remove_callback().
     */
    hash_table_remove(&page_ht, key, 2);
 
 
}
 
 
/** Find mapping for virtual page in page hash table.
 *
 * Find mapping for virtual page.
 *
 * The page table must be locked and interrupts must be disabled.
 *
 * @param as Address space to wich page belongs.
 * @param page Virtual page.
 *
 * @return NULL if there is no such mapping; requested mapping otherwise.
 */
pte_t *ht_mapping_find(as_t *as, __address page)
{
    link_t *hlp;
    pte_t *t = NULL;
    __native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
   
 
 
    hlp = hash_table_find(&page_ht, key);
    if (hlp)
        t = hash_table_get_instance(hlp, pte_t, link);
 
 
    return t;
}
 

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/genarch/src/mm/page_ht.c @ 922 – Rev 922 → 1044

Rev 922		Rev 1044
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	#include <genarch/mm/page_ht.h>	29	#include <genarch/mm/page_ht.h>
30	#include <mm/page.h>	30	#include <mm/page.h>
31	#include <arch/mm/page.h>	31	#include <arch/mm/page.h>
32	#include <mm/frame.h>	32	#include <mm/frame.h>
33	#include <mm/slab.h>	33	#include <mm/slab.h>
34	#include <mm/as.h>	34	#include <mm/as.h>
35	#include <arch/mm/asid.h>	35	#include <arch/mm/asid.h>
36	#include <arch/types.h>	36	#include <arch/types.h>
37	#include <typedefs.h>	37	#include <typedefs.h>
38	#include <arch/asm.h>	38	#include <arch/asm.h>
39	#include <synch/spinlock.h>	39	#include <synch/spinlock.h>
40	#include <arch.h>	40	#include <arch.h>
41	#include <debug.h>	41	#include <debug.h>
42	#include <memstr.h>	42	#include <memstr.h>
43	#include <adt/hash_table.h>	43	#include <adt/hash_table.h>
44	#include <align.h>	44	#include <align.h>
45		45
46	static index_t hash(__native key[]);	46	static index_t hash(__native key[]);
47	static bool compare(__native key[], count_t keys, link_t *item);	47	static bool compare(__native key[], count_t keys, link_t *item);
48	static void remove_callback(link_t *item);	48	static void remove_callback(link_t *item);
49		49
50	static void ht_mapping_insert(as_t *as, __address page, __address frame, int flags);	50	static void ht_mapping_insert(as_t *as, __address page, __address frame, int flags);
51	static void ht_mapping_remove(as_t *as, __address page);	51	static void ht_mapping_remove(as_t *as, __address page);
52	static pte_t ht_mapping_find(as_t as, __address page);	52	static pte_t ht_mapping_find(as_t as, __address page);
53		53
54	/**	54	/**
55	* This lock protects the page hash table.	55	* This lock protects the page hash table. It must be acquired
-		56	* after address space lock and after any address space area
-		57	* locks.
56	*/	58	*/
57	SPINLOCK_INITIALIZE(page_ht_lock);	59	SPINLOCK_INITIALIZE(page_ht_lock);
58		60
59	/**	61	/**
60	* Page hash table.	62	* Page hash table.
61	* The page hash table may be accessed only when page_ht_lock is held.	63	* The page hash table may be accessed only when page_ht_lock is held.
62	*/	64	*/
63	hash_table_t page_ht;	65	hash_table_t page_ht;
64		66
65	/** Hash table operations for page hash table. */	67	/** Hash table operations for page hash table. */
66	hash_table_operations_t ht_operations = {	68	hash_table_operations_t ht_operations = {
67	.hash = hash,	69	.hash = hash,
68	.compare = compare,	70	.compare = compare,
69	.remove_callback = remove_callback	71	.remove_callback = remove_callback
70	};	72	};
71		73
72	/** Page mapping operations for page hash table architectures. */	74	/** Page mapping operations for page hash table architectures. */
73	page_mapping_operations_t ht_mapping_operations = {	75	page_mapping_operations_t ht_mapping_operations = {
74	.mapping_insert = ht_mapping_insert,	76	.mapping_insert = ht_mapping_insert,
75	.mapping_remove = ht_mapping_remove,	77	.mapping_remove = ht_mapping_remove,
76	.mapping_find = ht_mapping_find	78	.mapping_find = ht_mapping_find
77	};	79	};
78		80
79	/** Compute page hash table index.	81	/** Compute page hash table index.
80	*	82	*
81	* @param key Array of two keys (i.e. page and address space).	83	* @param key Array of two keys (i.e. page and address space).
82	*	84	*
83	* @return Index into page hash table.	85	* @return Index into page hash table.
84	*/	86	*/
85	index_t hash(__native key[])	87	index_t hash(__native key[])
86	{	88	{
87	as_t as = (as_t ) key[KEY_AS];	89	as_t as = (as_t ) key[KEY_AS];
88	__address page = (__address) key[KEY_PAGE];	90	__address page = (__address) key[KEY_PAGE];
89	index_t index;	91	index_t index;
90		92
91	/*	93	/*
92	* Virtual page addresses have roughly the same probability	94	* Virtual page addresses have roughly the same probability
93	* of occurring. Least significant bits of VPN compose the	95	* of occurring. Least significant bits of VPN compose the
94	* hash index.	96	* hash index.
95	*/	97	*/
96	index = ((page >> PAGE_WIDTH) & (PAGE_HT_ENTRIES-1));	98	index = ((page >> PAGE_WIDTH) & (PAGE_HT_ENTRIES-1));
97		99
98	/*	100	/*
99	* Address space structures are likely to be allocated from	101	* Address space structures are likely to be allocated from
100	* similar addresses. Least significant bits compose the	102	* similar addresses. Least significant bits compose the
101	* hash index.	103	* hash index.
102	*/	104	*/
103	index \|= ((__native) as) & (PAGE_HT_ENTRIES-1);	105	index \|= ((__native) as) & (PAGE_HT_ENTRIES-1);
104		106
105	return index;	107	return index;
106	}	108	}
107		109
108	/** Compare page hash table item with page and/or address space.	110	/** Compare page hash table item with page and/or address space.
109	*	111	*
110	* @param key Array of one or two keys (i.e. page and/or address space).	112	* @param key Array of one or two keys (i.e. page and/or address space).
111	* @param keys Number of keys passed.	113	* @param keys Number of keys passed.
112	* @param item Item to compare the keys with.	114	* @param item Item to compare the keys with.
113	*	115	*
114	* @return true on match, false otherwise.	116	* @return true on match, false otherwise.
115	*/	117	*/
116	bool compare(__native key[], count_t keys, link_t *item)	118	bool compare(__native key[], count_t keys, link_t *item)
117	{	119	{
118	pte_t *t;	120	pte_t *t;
119		121
120	ASSERT(item);	122	ASSERT(item);
121	ASSERT((keys > 0) && (keys <= PAGE_HT_KEYS));	123	ASSERT((keys > 0) && (keys <= PAGE_HT_KEYS));
122		124
123	/*	125	/*
124	* Convert item to PTE.	126	* Convert item to PTE.
125	*/	127	*/
126	t = hash_table_get_instance(item, pte_t, link);	128	t = hash_table_get_instance(item, pte_t, link);
127		129
128	if (keys == PAGE_HT_KEYS) {	130	if (keys == PAGE_HT_KEYS) {
129	return (key[KEY_AS] == (__address) t->as) && (key[KEY_PAGE] == t->page);	131	return (key[KEY_AS] == (__address) t->as) && (key[KEY_PAGE] == t->page);
130	} else {	132	} else {
131	return (key[KEY_AS] == (__address) t->as);	133	return (key[KEY_AS] == (__address) t->as);
132	}	134	}
133	}	135	}
134		136
135	/** Callback on page hash table item removal.	137	/** Callback on page hash table item removal.
136	*	138	*
137	* @param item Page hash table item being removed.	139	* @param item Page hash table item being removed.
138	*/	140	*/
139	void remove_callback(link_t *item)	141	void remove_callback(link_t *item)
140	{	142	{
141	pte_t *t;	143	pte_t *t;
142		144
143	ASSERT(item);	145	ASSERT(item);
144		146
145	/*	147	/*
146	* Convert item to PTE.	148	* Convert item to PTE.
147	*/	149	*/
148	t = hash_table_get_instance(item, pte_t, link);	150	t = hash_table_get_instance(item, pte_t, link);
149		151
150	free(t);	152	free(t);
151	}	153	}
152		154
153	/** Map page to frame using page hash table.	155	/** Map page to frame using page hash table.
154	*	156	*
155	* Map virtual address 'page' to physical address 'frame'	157	* Map virtual address 'page' to physical address 'frame'
156	* using 'flags'.	158	* using 'flags'.
157	*	159	*
158	* The address space must be locked and interruptsmust be disabled.	160	* The page table must be locked and interrupts must be disabled.
159	*	161	*
160	* @param as Address space to which page belongs.	162	* @param as Address space to which page belongs.
161	* @param page Virtual address of the page to be mapped.	163	* @param page Virtual address of the page to be mapped.
162	* @param frame Physical address of memory frame to which the mapping is done.	164	* @param frame Physical address of memory frame to which the mapping is done.
163	* @param flags Flags to be used for mapping.	165	* @param flags Flags to be used for mapping.
164	*/	166	*/
165	void ht_mapping_insert(as_t *as, __address page, __address frame, int flags)	167	void ht_mapping_insert(as_t *as, __address page, __address frame, int flags)
166	{	168	{
167	pte_t *t;	169	pte_t *t;
168	__native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };	170	__native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
169		171
170	spinlock_lock(&page_ht_lock);	-
171		-
172	if (!hash_table_find(&page_ht, key)) {	172	if (!hash_table_find(&page_ht, key)) {
173	t = (pte_t *) malloc(sizeof(pte_t), FRAME_ATOMIC);	173	t = (pte_t *) malloc(sizeof(pte_t), FRAME_ATOMIC);
174	ASSERT(t != NULL);	174	ASSERT(t != NULL);
175		175
176	t->g = (flags & PAGE_GLOBAL) != 0;	176	t->g = (flags & PAGE_GLOBAL) != 0;
177	t->x = (flags & PAGE_EXEC) != 0;	177	t->x = (flags & PAGE_EXEC) != 0;
178	t->w = (flags & PAGE_WRITE) != 0;	178	t->w = (flags & PAGE_WRITE) != 0;
179	t->k = !(flags & PAGE_USER);	179	t->k = !(flags & PAGE_USER);
180	t->c = (flags & PAGE_CACHEABLE) != 0;	180	t->c = (flags & PAGE_CACHEABLE) != 0;
181	t->p = !(flags & PAGE_NOT_PRESENT);	181	t->p = !(flags & PAGE_NOT_PRESENT);
182		182
183	t->as = as;	183	t->as = as;
184	t->page = page;	184	t->page = page;
185	t->frame = frame;	185	t->frame = frame;
186		186
187	hash_table_insert(&page_ht, key, &t->link);	187	hash_table_insert(&page_ht, key, &t->link);
188	}	188	}
189		-
190	spinlock_unlock(&page_ht_lock);	-
191	}	189	}
192		190
193	/** Remove mapping of page from page hash table.	191	/** Remove mapping of page from page hash table.
194	*	192	*
195	* Remove any mapping of 'page' within address space 'as'.	193	* Remove any mapping of 'page' within address space 'as'.
196	* TLB shootdown should follow in order to make effects of	194	* TLB shootdown should follow in order to make effects of
197	* this call visible.	195	* this call visible.
198	*	196	*
199	* The address space must be locked and interrupts must be disabled.	197	* The page table must be locked and interrupts must be disabled.
200	*	198	*
201	* @param as Address space to wich page belongs.	199	* @param as Address space to wich page belongs.
202	* @param page Virtual address of the page to be demapped.	200	* @param page Virtual address of the page to be demapped.
203	*/	201	*/
204	void ht_mapping_remove(as_t *as, __address page)	202	void ht_mapping_remove(as_t *as, __address page)
205	{	203	{
206	__native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };	204	__native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
207		205
208	spinlock_lock(&page_ht_lock);	-
209		-
210	/*	206	/*
211	* Note that removed PTE's will be freed	207	* Note that removed PTE's will be freed
212	* by remove_callback().	208	* by remove_callback().
213	*/	209	*/
214	hash_table_remove(&page_ht, key, 2);	210	hash_table_remove(&page_ht, key, 2);
215		-
216	spinlock_unlock(&page_ht_lock);	-
217	}	211	}
218		212
219		213
220	/** Find mapping for virtual page in page hash table.	214	/** Find mapping for virtual page in page hash table.
221	*	215	*
222	* Find mapping for virtual page.	216	* Find mapping for virtual page.
223	*	217	*
224	* The address space must be locked and interrupts must be disabled.	218	* The page table must be locked and interrupts must be disabled.
225	*	219	*
226	* @param as Address space to wich page belongs.	220	* @param as Address space to wich page belongs.
227	* @param page Virtual page.	221	* @param page Virtual page.
228	*	222	*
229	* @return NULL if there is no such mapping; requested mapping otherwise.	223	* @return NULL if there is no such mapping; requested mapping otherwise.
230	*/	224	*/
231	pte_t ht_mapping_find(as_t as, __address page)	225	pte_t ht_mapping_find(as_t as, __address page)
232	{	226	{
233	link_t *hlp;	227	link_t *hlp;
234	pte_t *t = NULL;	228	pte_t *t = NULL;
235	__native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };	229	__native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
236		230
237	spinlock_lock(&page_ht_lock);	-
238		-
239	hlp = hash_table_find(&page_ht, key);	231	hlp = hash_table_find(&page_ht, key);
240	if (hlp)	232	if (hlp)
241	t = hash_table_get_instance(hlp, pte_t, link);	233	t = hash_table_get_instance(hlp, pte_t, link);
242		234
243	spinlock_unlock(&page_ht_lock);	-
244	return t;	235	return t;
245	}	236	}
246		237