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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 futex.c |
|
30 | * Kernel backend for futexes. |
31 | * @brief Kernel backend for futexes. |
- | 32 | * |
|
31 | * Deallocation of orphaned kernel-side futex structures is not currently implemented. |
33 | * @todo Deallocation of orphaned kernel-side futex structures is not currently implemented. |
32 | */ |
34 | */ |
33 | 35 | ||
34 | #include <synch/futex.h> |
36 | #include <synch/futex.h> |
35 | #include <synch/rwlock.h> |
37 | #include <synch/rwlock.h> |
36 | #include <synch/spinlock.h> |
38 | #include <synch/spinlock.h> |
37 | #include <synch/synch.h> |
39 | #include <synch/synch.h> |
38 | #include <mm/frame.h> |
40 | #include <mm/frame.h> |
39 | #include <mm/page.h> |
41 | #include <mm/page.h> |
40 | #include <mm/slab.h> |
42 | #include <mm/slab.h> |
41 | #include <proc/thread.h> |
43 | #include <proc/thread.h> |
42 | #include <genarch/mm/page_pt.h> |
44 | #include <genarch/mm/page_pt.h> |
43 | #include <genarch/mm/page_ht.h> |
45 | #include <genarch/mm/page_ht.h> |
44 | #include <adt/hash_table.h> |
46 | #include <adt/hash_table.h> |
45 | #include <adt/list.h> |
47 | #include <adt/list.h> |
46 | #include <arch.h> |
48 | #include <arch.h> |
47 | #include <align.h> |
49 | #include <align.h> |
48 | #include <panic.h> |
50 | #include <panic.h> |
49 | #include <errno.h> |
51 | #include <errno.h> |
50 | #include <print.h> |
52 | #include <print.h> |
51 | 53 | ||
52 | #define FUTEX_HT_SIZE 1024 /* keep it a power of 2 */ |
54 | #define FUTEX_HT_SIZE 1024 /* keep it a power of 2 */ |
53 | 55 | ||
54 | static void futex_initialize(futex_t *futex); |
56 | static void futex_initialize(futex_t *futex); |
55 | 57 | ||
56 | static futex_t *futex_find(__address paddr); |
58 | static futex_t *futex_find(__address paddr); |
57 | static index_t futex_ht_hash(__native *key); |
59 | static index_t futex_ht_hash(__native *key); |
58 | static bool futex_ht_compare(__native *key, count_t keys, link_t *item); |
60 | static bool futex_ht_compare(__native *key, count_t keys, link_t *item); |
59 | static void futex_ht_remove_callback(link_t *item); |
61 | static void futex_ht_remove_callback(link_t *item); |
60 | 62 | ||
61 | /** Read-write lock protecting global futex hash table. */ |
63 | /** Read-write lock protecting global futex hash table. */ |
62 | static rwlock_t futex_ht_lock; |
64 | static rwlock_t futex_ht_lock; |
63 | 65 | ||
64 | /** Futex hash table. */ |
66 | /** Futex hash table. */ |
65 | static hash_table_t futex_ht; |
67 | static hash_table_t futex_ht; |
66 | 68 | ||
67 | /** Futex hash table operations. */ |
69 | /** Futex hash table operations. */ |
68 | static hash_table_operations_t futex_ht_ops = { |
70 | static hash_table_operations_t futex_ht_ops = { |
69 | .hash = futex_ht_hash, |
71 | .hash = futex_ht_hash, |
70 | .compare = futex_ht_compare, |
72 | .compare = futex_ht_compare, |
71 | .remove_callback = futex_ht_remove_callback |
73 | .remove_callback = futex_ht_remove_callback |
72 | }; |
74 | }; |
73 | 75 | ||
74 | /** Initialize futex subsystem. */ |
76 | /** Initialize futex subsystem. */ |
75 | void futex_init(void) |
77 | void futex_init(void) |
76 | { |
78 | { |
77 | rwlock_initialize(&futex_ht_lock); |
79 | rwlock_initialize(&futex_ht_lock); |
78 | hash_table_create(&futex_ht, FUTEX_HT_SIZE, 1, &futex_ht_ops); |
80 | hash_table_create(&futex_ht, FUTEX_HT_SIZE, 1, &futex_ht_ops); |
79 | } |
81 | } |
80 | 82 | ||
81 | /** Initialize kernel futex structure. |
83 | /** Initialize kernel futex structure. |
82 | * |
84 | * |
83 | * @param futex Kernel futex structure. |
85 | * @param futex Kernel futex structure. |
84 | */ |
86 | */ |
85 | void futex_initialize(futex_t *futex) |
87 | void futex_initialize(futex_t *futex) |
86 | { |
88 | { |
87 | waitq_initialize(&futex->wq); |
89 | waitq_initialize(&futex->wq); |
88 | link_initialize(&futex->ht_link); |
90 | link_initialize(&futex->ht_link); |
89 | futex->paddr = 0; |
91 | futex->paddr = 0; |
90 | } |
92 | } |
91 | 93 | ||
92 | /** Sleep in futex wait queue. |
94 | /** Sleep in futex wait queue. |
93 | * |
95 | * |
94 | * @param uaddr Userspace address of the futex counter. |
96 | * @param uaddr Userspace address of the futex counter. |
95 | * @param usec If non-zero, number of microseconds this thread is willing to sleep. |
97 | * @param usec If non-zero, number of microseconds this thread is willing to sleep. |
96 | * @param trydown If usec is zero and trydown is non-zero, conditional operation will be attempted. |
98 | * @param trydown If usec is zero and trydown is non-zero, conditional operation will be attempted. |
97 | * |
99 | * |
98 | * @return One of ESYNCH_TIMEOUT, ESYNCH_OK_ATOMIC and ESYNCH_OK_BLOCKED. See synch.h. |
100 | * @return One of ESYNCH_TIMEOUT, ESYNCH_OK_ATOMIC and ESYNCH_OK_BLOCKED. See synch.h. |
99 | * If there is no physical mapping for uaddr ENOENT is returned. |
101 | * If there is no physical mapping for uaddr ENOENT is returned. |
100 | */ |
102 | */ |
101 | __native sys_futex_sleep_timeout(__address uaddr, __u32 usec, int trydown) |
103 | __native sys_futex_sleep_timeout(__address uaddr, __u32 usec, int trydown) |
102 | { |
104 | { |
103 | futex_t *futex; |
105 | futex_t *futex; |
104 | __address paddr; |
106 | __address paddr; |
105 | pte_t *t; |
107 | pte_t *t; |
106 | ipl_t ipl; |
108 | ipl_t ipl; |
107 | 109 | ||
108 | ipl = interrupts_disable(); |
110 | ipl = interrupts_disable(); |
109 | 111 | ||
110 | /* |
112 | /* |
111 | * Find physical address of futex counter. |
113 | * Find physical address of futex counter. |
112 | */ |
114 | */ |
113 | page_table_lock(AS, true); |
115 | page_table_lock(AS, true); |
114 | t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE)); |
116 | t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE)); |
115 | if (!t || !PTE_VALID(t) || !PTE_PRESENT(t)) { |
117 | if (!t || !PTE_VALID(t) || !PTE_PRESENT(t)) { |
116 | page_table_unlock(AS, true); |
118 | page_table_unlock(AS, true); |
117 | interrupts_restore(ipl); |
119 | interrupts_restore(ipl); |
118 | return (__native) ENOENT; |
120 | return (__native) ENOENT; |
119 | } |
121 | } |
120 | paddr = PFN2ADDR(PTE_GET_FRAME(t)) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE)); |
122 | paddr = PFN2ADDR(PTE_GET_FRAME(t)) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE)); |
121 | page_table_unlock(AS, true); |
123 | page_table_unlock(AS, true); |
122 | 124 | ||
123 | interrupts_restore(ipl); |
125 | interrupts_restore(ipl); |
124 | 126 | ||
125 | futex = futex_find(paddr); |
127 | futex = futex_find(paddr); |
126 | 128 | ||
127 | return (__native) waitq_sleep_timeout(&futex->wq, usec, trydown); |
129 | return (__native) waitq_sleep_timeout(&futex->wq, usec, trydown); |
128 | } |
130 | } |
129 | 131 | ||
130 | /** Wakeup one thread waiting in futex wait queue. |
132 | /** Wakeup one thread waiting in futex wait queue. |
131 | * |
133 | * |
132 | * @param uaddr Userspace address of the futex counter. |
134 | * @param uaddr Userspace address of the futex counter. |
133 | * |
135 | * |
134 | * @return ENOENT if there is no futex associated with the address |
136 | * @return ENOENT if there is no futex associated with the address |
135 | * or if there is no physical mapping for uaddr. |
137 | * or if there is no physical mapping for uaddr. |
136 | */ |
138 | */ |
137 | __native sys_futex_wakeup(__address uaddr) |
139 | __native sys_futex_wakeup(__address uaddr) |
138 | { |
140 | { |
139 | futex_t *futex; |
141 | futex_t *futex; |
140 | __address paddr; |
142 | __address paddr; |
141 | pte_t *t; |
143 | pte_t *t; |
142 | ipl_t ipl; |
144 | ipl_t ipl; |
143 | 145 | ||
144 | ipl = interrupts_disable(); |
146 | ipl = interrupts_disable(); |
145 | 147 | ||
146 | /* |
148 | /* |
147 | * Find physical address of futex counter. |
149 | * Find physical address of futex counter. |
148 | */ |
150 | */ |
149 | page_table_lock(AS, true); |
151 | page_table_lock(AS, true); |
150 | t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE)); |
152 | t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE)); |
151 | if (!t || !PTE_VALID(t) || !PTE_PRESENT(t)) { |
153 | if (!t || !PTE_VALID(t) || !PTE_PRESENT(t)) { |
152 | page_table_unlock(AS, true); |
154 | page_table_unlock(AS, true); |
153 | interrupts_restore(ipl); |
155 | interrupts_restore(ipl); |
154 | return (__native) ENOENT; |
156 | return (__native) ENOENT; |
155 | } |
157 | } |
156 | paddr = PFN2ADDR(PTE_GET_FRAME(t)) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE)); |
158 | paddr = PFN2ADDR(PTE_GET_FRAME(t)) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE)); |
157 | page_table_unlock(AS, true); |
159 | page_table_unlock(AS, true); |
158 | 160 | ||
159 | interrupts_restore(ipl); |
161 | interrupts_restore(ipl); |
160 | 162 | ||
161 | futex = futex_find(paddr); |
163 | futex = futex_find(paddr); |
162 | 164 | ||
163 | waitq_wakeup(&futex->wq, WAKEUP_FIRST); |
165 | waitq_wakeup(&futex->wq, WAKEUP_FIRST); |
164 | 166 | ||
165 | return 0; |
167 | return 0; |
166 | } |
168 | } |
167 | 169 | ||
168 | /** Find kernel address of the futex structure corresponding to paddr. |
170 | /** Find kernel address of the futex structure corresponding to paddr. |
169 | * |
171 | * |
170 | * If the structure does not exist alreay, a new one is created. |
172 | * If the structure does not exist alreay, a new one is created. |
171 | * |
173 | * |
172 | * @param paddr Physical address of the userspace futex counter. |
174 | * @param paddr Physical address of the userspace futex counter. |
173 | * |
175 | * |
174 | * @return Address of the kernel futex structure. |
176 | * @return Address of the kernel futex structure. |
175 | */ |
177 | */ |
176 | futex_t *futex_find(__address paddr) |
178 | futex_t *futex_find(__address paddr) |
177 | { |
179 | { |
178 | link_t *item; |
180 | link_t *item; |
179 | futex_t *futex; |
181 | futex_t *futex; |
180 | 182 | ||
181 | /* |
183 | /* |
182 | * Find the respective futex structure |
184 | * Find the respective futex structure |
183 | * or allocate new one if it does not exist already. |
185 | * or allocate new one if it does not exist already. |
184 | */ |
186 | */ |
185 | rwlock_read_lock(&futex_ht_lock); |
187 | rwlock_read_lock(&futex_ht_lock); |
186 | item = hash_table_find(&futex_ht, &paddr); |
188 | item = hash_table_find(&futex_ht, &paddr); |
187 | if (item) { |
189 | if (item) { |
188 | futex = hash_table_get_instance(item, futex_t, ht_link); |
190 | futex = hash_table_get_instance(item, futex_t, ht_link); |
189 | rwlock_read_unlock(&futex_ht_lock); |
191 | rwlock_read_unlock(&futex_ht_lock); |
190 | } else { |
192 | } else { |
191 | /* |
193 | /* |
192 | * Upgrade to writer is not currently supported, |
194 | * Upgrade to writer is not currently supported, |
193 | * Therefore, it is necessary to release the read lock |
195 | * Therefore, it is necessary to release the read lock |
194 | * and reacquire it as a writer. |
196 | * and reacquire it as a writer. |
195 | */ |
197 | */ |
196 | rwlock_read_unlock(&futex_ht_lock); |
198 | rwlock_read_unlock(&futex_ht_lock); |
197 | 199 | ||
198 | rwlock_write_lock(&futex_ht_lock); |
200 | rwlock_write_lock(&futex_ht_lock); |
199 | /* |
201 | /* |
200 | * Avoid possible race condition by searching |
202 | * Avoid possible race condition by searching |
201 | * the hash table once again with write access. |
203 | * the hash table once again with write access. |
202 | */ |
204 | */ |
203 | item = hash_table_find(&futex_ht, &paddr); |
205 | item = hash_table_find(&futex_ht, &paddr); |
204 | if (item) { |
206 | if (item) { |
205 | futex = hash_table_get_instance(item, futex_t, ht_link); |
207 | futex = hash_table_get_instance(item, futex_t, ht_link); |
206 | rwlock_write_unlock(&futex_ht_lock); |
208 | rwlock_write_unlock(&futex_ht_lock); |
207 | } else { |
209 | } else { |
208 | futex = (futex_t *) malloc(sizeof(futex_t), 0); |
210 | futex = (futex_t *) malloc(sizeof(futex_t), 0); |
209 | futex_initialize(futex); |
211 | futex_initialize(futex); |
210 | futex->paddr = paddr; |
212 | futex->paddr = paddr; |
211 | hash_table_insert(&futex_ht, &paddr, &futex->ht_link); |
213 | hash_table_insert(&futex_ht, &paddr, &futex->ht_link); |
212 | rwlock_write_unlock(&futex_ht_lock); |
214 | rwlock_write_unlock(&futex_ht_lock); |
213 | } |
215 | } |
214 | } |
216 | } |
215 | 217 | ||
216 | return futex; |
218 | return futex; |
217 | } |
219 | } |
218 | 220 | ||
219 | /** Compute hash index into futex hash table. |
221 | /** Compute hash index into futex hash table. |
220 | * |
222 | * |
221 | * @param key Address where the key (i.e. physical address of futex counter) is stored. |
223 | * @param key Address where the key (i.e. physical address of futex counter) is stored. |
222 | * |
224 | * |
223 | * @return Index into futex hash table. |
225 | * @return Index into futex hash table. |
224 | */ |
226 | */ |
225 | index_t futex_ht_hash(__native *key) |
227 | index_t futex_ht_hash(__native *key) |
226 | { |
228 | { |
227 | return *key & (FUTEX_HT_SIZE-1); |
229 | return *key & (FUTEX_HT_SIZE-1); |
228 | } |
230 | } |
229 | 231 | ||
230 | /** Compare futex hash table item with a key. |
232 | /** Compare futex hash table item with a key. |
231 | * |
233 | * |
232 | * @param key Address where the key (i.e. physical address of futex counter) is stored. |
234 | * @param key Address where the key (i.e. physical address of futex counter) is stored. |
233 | * |
235 | * |
234 | * @return True if the item matches the key. False otherwise. |
236 | * @return True if the item matches the key. False otherwise. |
235 | */ |
237 | */ |
236 | bool futex_ht_compare(__native *key, count_t keys, link_t *item) |
238 | bool futex_ht_compare(__native *key, count_t keys, link_t *item) |
237 | { |
239 | { |
238 | futex_t *futex; |
240 | futex_t *futex; |
239 | 241 | ||
240 | ASSERT(keys == 1); |
242 | ASSERT(keys == 1); |
241 | 243 | ||
242 | futex = hash_table_get_instance(item, futex_t, ht_link); |
244 | futex = hash_table_get_instance(item, futex_t, ht_link); |
243 | return *key == futex->paddr; |
245 | return *key == futex->paddr; |
244 | } |
246 | } |
245 | 247 | ||
246 | /** Callback for removal items from futex hash table. |
248 | /** Callback for removal items from futex hash table. |
247 | * |
249 | * |
248 | * @param item Item removed from the hash table. |
250 | * @param item Item removed from the hash table. |
249 | */ |
251 | */ |
250 | void futex_ht_remove_callback(link_t *item) |
252 | void futex_ht_remove_callback(link_t *item) |
251 | { |
253 | { |
252 | futex_t *futex; |
254 | futex_t *futex; |
253 | 255 | ||
254 | futex = hash_table_get_instance(item, futex_t, ht_link); |
256 | futex = hash_table_get_instance(item, futex_t, ht_link); |
255 | free(futex); |
257 | free(futex); |
256 | } |
258 | } |
257 | 259 |