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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 | * @file futex.c |
31 | * @brief Kernel backend for futexes. |
31 | * @brief Kernel backend for futexes. |
32 | * |
- | |
33 | * @todo Deallocation of orphaned kernel-side futex structures is not currently implemented. |
- | |
34 | */ |
32 | */ |
35 | 33 | ||
36 | #include <synch/futex.h> |
34 | #include <synch/futex.h> |
37 | #include <synch/rwlock.h> |
35 | #include <synch/rwlock.h> |
38 | #include <synch/spinlock.h> |
36 | #include <synch/spinlock.h> |
39 | #include <synch/synch.h> |
37 | #include <synch/synch.h> |
40 | #include <mm/frame.h> |
38 | #include <mm/frame.h> |
41 | #include <mm/page.h> |
39 | #include <mm/page.h> |
42 | #include <mm/slab.h> |
40 | #include <mm/slab.h> |
43 | #include <proc/thread.h> |
41 | #include <proc/thread.h> |
- | 42 | #include <proc/task.h> |
|
44 | #include <genarch/mm/page_pt.h> |
43 | #include <genarch/mm/page_pt.h> |
45 | #include <genarch/mm/page_ht.h> |
44 | #include <genarch/mm/page_ht.h> |
46 | #include <adt/hash_table.h> |
45 | #include <adt/hash_table.h> |
47 | #include <adt/list.h> |
46 | #include <adt/list.h> |
48 | #include <arch.h> |
47 | #include <arch.h> |
49 | #include <align.h> |
48 | #include <align.h> |
50 | #include <panic.h> |
49 | #include <panic.h> |
51 | #include <errno.h> |
50 | #include <errno.h> |
52 | #include <print.h> |
51 | #include <print.h> |
53 | 52 | ||
54 | #define FUTEX_HT_SIZE 1024 /* keep it a power of 2 */ |
53 | #define FUTEX_HT_SIZE 1024 /* keep it a power of 2 */ |
55 | 54 | ||
56 | static void futex_initialize(futex_t *futex); |
55 | static void futex_initialize(futex_t *futex); |
57 | 56 | ||
58 | static futex_t *futex_find(__address paddr); |
57 | static futex_t *futex_find(__address paddr); |
59 | static index_t futex_ht_hash(__native *key); |
58 | static index_t futex_ht_hash(__native *key); |
60 | static bool futex_ht_compare(__native *key, count_t keys, link_t *item); |
59 | static bool futex_ht_compare(__native *key, count_t keys, link_t *item); |
61 | static void futex_ht_remove_callback(link_t *item); |
60 | static void futex_ht_remove_callback(link_t *item); |
62 | 61 | ||
- | 62 | /** |
|
63 | /** Read-write lock protecting global futex hash table. */ |
63 | * Read-write lock protecting global futex hash table. |
- | 64 | * It is also used to serialize access to all futex_t structures. |
|
- | 65 | * Must be acquired before the task futex B+tree lock. |
|
- | 66 | */ |
|
64 | static rwlock_t futex_ht_lock; |
67 | static rwlock_t futex_ht_lock; |
65 | 68 | ||
66 | /** Futex hash table. */ |
69 | /** Futex hash table. */ |
67 | static hash_table_t futex_ht; |
70 | static hash_table_t futex_ht; |
68 | 71 | ||
69 | /** Futex hash table operations. */ |
72 | /** Futex hash table operations. */ |
70 | static hash_table_operations_t futex_ht_ops = { |
73 | static hash_table_operations_t futex_ht_ops = { |
71 | .hash = futex_ht_hash, |
74 | .hash = futex_ht_hash, |
72 | .compare = futex_ht_compare, |
75 | .compare = futex_ht_compare, |
73 | .remove_callback = futex_ht_remove_callback |
76 | .remove_callback = futex_ht_remove_callback |
74 | }; |
77 | }; |
75 | 78 | ||
76 | /** Initialize futex subsystem. */ |
79 | /** Initialize futex subsystem. */ |
77 | void futex_init(void) |
80 | void futex_init(void) |
78 | { |
81 | { |
79 | rwlock_initialize(&futex_ht_lock); |
82 | rwlock_initialize(&futex_ht_lock); |
80 | hash_table_create(&futex_ht, FUTEX_HT_SIZE, 1, &futex_ht_ops); |
83 | hash_table_create(&futex_ht, FUTEX_HT_SIZE, 1, &futex_ht_ops); |
81 | } |
84 | } |
82 | 85 | ||
83 | /** Initialize kernel futex structure. |
86 | /** Initialize kernel futex structure. |
84 | * |
87 | * |
85 | * @param futex Kernel futex structure. |
88 | * @param futex Kernel futex structure. |
86 | */ |
89 | */ |
87 | void futex_initialize(futex_t *futex) |
90 | void futex_initialize(futex_t *futex) |
88 | { |
91 | { |
89 | waitq_initialize(&futex->wq); |
92 | waitq_initialize(&futex->wq); |
90 | link_initialize(&futex->ht_link); |
93 | link_initialize(&futex->ht_link); |
91 | futex->paddr = 0; |
94 | futex->paddr = 0; |
- | 95 | futex->refcount = 1; |
|
92 | } |
96 | } |
93 | 97 | ||
94 | /** Sleep in futex wait queue. |
98 | /** Sleep in futex wait queue. |
95 | * |
99 | * |
96 | * @param uaddr Userspace address of the futex counter. |
100 | * @param uaddr Userspace address of the futex counter. |
97 | * @param usec If non-zero, number of microseconds this thread is willing to sleep. |
101 | * @param usec If non-zero, number of microseconds this thread is willing to sleep. |
98 | * @param trydown If usec is zero and trydown is non-zero, conditional operation will be attempted. |
102 | * @param trydown If usec is zero and trydown is non-zero, conditional operation will be attempted. |
99 | * |
103 | * |
100 | * @return One of ESYNCH_TIMEOUT, ESYNCH_OK_ATOMIC and ESYNCH_OK_BLOCKED. See synch.h. |
104 | * @return One of ESYNCH_TIMEOUT, ESYNCH_OK_ATOMIC and ESYNCH_OK_BLOCKED. See synch.h. |
101 | * If there is no physical mapping for uaddr ENOENT is returned. |
105 | * If there is no physical mapping for uaddr ENOENT is returned. |
102 | */ |
106 | */ |
103 | __native sys_futex_sleep_timeout(__address uaddr, __u32 usec, int trydown) |
107 | __native sys_futex_sleep_timeout(__address uaddr, __u32 usec, int trydown) |
104 | { |
108 | { |
105 | futex_t *futex; |
109 | futex_t *futex; |
106 | __address paddr; |
110 | __address paddr; |
107 | pte_t *t; |
111 | pte_t *t; |
108 | ipl_t ipl; |
112 | ipl_t ipl; |
109 | 113 | ||
110 | ipl = interrupts_disable(); |
114 | ipl = interrupts_disable(); |
111 | 115 | ||
112 | /* |
116 | /* |
113 | * Find physical address of futex counter. |
117 | * Find physical address of futex counter. |
114 | */ |
118 | */ |
115 | page_table_lock(AS, true); |
119 | page_table_lock(AS, true); |
116 | t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE)); |
120 | t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE)); |
117 | if (!t || !PTE_VALID(t) || !PTE_PRESENT(t)) { |
121 | if (!t || !PTE_VALID(t) || !PTE_PRESENT(t)) { |
118 | page_table_unlock(AS, true); |
122 | page_table_unlock(AS, true); |
119 | interrupts_restore(ipl); |
123 | interrupts_restore(ipl); |
120 | return (__native) ENOENT; |
124 | return (__native) ENOENT; |
121 | } |
125 | } |
122 | paddr = PTE_GET_FRAME(t) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE)); |
126 | paddr = PTE_GET_FRAME(t) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE)); |
123 | page_table_unlock(AS, true); |
127 | page_table_unlock(AS, true); |
124 | 128 | ||
125 | interrupts_restore(ipl); |
129 | interrupts_restore(ipl); |
126 | 130 | ||
127 | futex = futex_find(paddr); |
131 | futex = futex_find(paddr); |
128 | 132 | ||
129 | return (__native) waitq_sleep_timeout(&futex->wq, usec, trydown); |
133 | return (__native) waitq_sleep_timeout(&futex->wq, usec, trydown); |
130 | } |
134 | } |
131 | 135 | ||
132 | /** Wakeup one thread waiting in futex wait queue. |
136 | /** Wakeup one thread waiting in futex wait queue. |
133 | * |
137 | * |
134 | * @param uaddr Userspace address of the futex counter. |
138 | * @param uaddr Userspace address of the futex counter. |
135 | * |
139 | * |
136 | * @return ENOENT if there is no physical mapping for uaddr. |
140 | * @return ENOENT if there is no physical mapping for uaddr. |
137 | */ |
141 | */ |
138 | __native sys_futex_wakeup(__address uaddr) |
142 | __native sys_futex_wakeup(__address uaddr) |
139 | { |
143 | { |
140 | futex_t *futex; |
144 | futex_t *futex; |
141 | __address paddr; |
145 | __address paddr; |
142 | pte_t *t; |
146 | pte_t *t; |
143 | ipl_t ipl; |
147 | ipl_t ipl; |
144 | 148 | ||
145 | ipl = interrupts_disable(); |
149 | ipl = interrupts_disable(); |
146 | 150 | ||
147 | /* |
151 | /* |
148 | * Find physical address of futex counter. |
152 | * Find physical address of futex counter. |
149 | */ |
153 | */ |
150 | page_table_lock(AS, true); |
154 | page_table_lock(AS, true); |
151 | t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE)); |
155 | t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE)); |
152 | if (!t || !PTE_VALID(t) || !PTE_PRESENT(t)) { |
156 | if (!t || !PTE_VALID(t) || !PTE_PRESENT(t)) { |
153 | page_table_unlock(AS, true); |
157 | page_table_unlock(AS, true); |
154 | interrupts_restore(ipl); |
158 | interrupts_restore(ipl); |
155 | return (__native) ENOENT; |
159 | return (__native) ENOENT; |
156 | } |
160 | } |
157 | paddr = PTE_GET_FRAME(t) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE)); |
161 | paddr = PTE_GET_FRAME(t) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE)); |
158 | page_table_unlock(AS, true); |
162 | page_table_unlock(AS, true); |
159 | 163 | ||
160 | interrupts_restore(ipl); |
164 | interrupts_restore(ipl); |
161 | 165 | ||
162 | futex = futex_find(paddr); |
166 | futex = futex_find(paddr); |
163 | 167 | ||
164 | waitq_wakeup(&futex->wq, WAKEUP_FIRST); |
168 | waitq_wakeup(&futex->wq, WAKEUP_FIRST); |
165 | 169 | ||
166 | return 0; |
170 | return 0; |
167 | } |
171 | } |
168 | 172 | ||
169 | /** Find kernel address of the futex structure corresponding to paddr. |
173 | /** Find kernel address of the futex structure corresponding to paddr. |
170 | * |
174 | * |
171 | * If the structure does not exist alreay, a new one is created. |
175 | * If the structure does not exist already, a new one is created. |
172 | * |
176 | * |
173 | * @param paddr Physical address of the userspace futex counter. |
177 | * @param paddr Physical address of the userspace futex counter. |
174 | * |
178 | * |
175 | * @return Address of the kernel futex structure. |
179 | * @return Address of the kernel futex structure. |
176 | */ |
180 | */ |
177 | futex_t *futex_find(__address paddr) |
181 | futex_t *futex_find(__address paddr) |
178 | { |
182 | { |
179 | link_t *item; |
183 | link_t *item; |
180 | futex_t *futex; |
184 | futex_t *futex; |
- | 185 | btree_node_t *leaf; |
|
181 | 186 | ||
182 | /* |
187 | /* |
183 | * Find the respective futex structure |
188 | * Find the respective futex structure |
184 | * or allocate new one if it does not exist already. |
189 | * or allocate new one if it does not exist already. |
185 | */ |
190 | */ |
186 | rwlock_read_lock(&futex_ht_lock); |
191 | rwlock_read_lock(&futex_ht_lock); |
187 | item = hash_table_find(&futex_ht, &paddr); |
192 | item = hash_table_find(&futex_ht, &paddr); |
188 | if (item) { |
193 | if (item) { |
189 | futex = hash_table_get_instance(item, futex_t, ht_link); |
194 | futex = hash_table_get_instance(item, futex_t, ht_link); |
- | 195 | ||
- | 196 | /* |
|
- | 197 | * See if the current task knows this futex. |
|
- | 198 | */ |
|
- | 199 | mutex_lock(&TASK->futexes_lock); |
|
- | 200 | if (!btree_search(&TASK->futexes, paddr, &leaf)) { |
|
- | 201 | /* |
|
- | 202 | * The futex is new to the current task. |
|
- | 203 | * However, we only have read access. |
|
- | 204 | * Gain write access and try again. |
|
- | 205 | */ |
|
- | 206 | mutex_unlock(&TASK->futexes_lock); |
|
- | 207 | goto gain_write_access; |
|
- | 208 | } |
|
- | 209 | mutex_unlock(&TASK->futexes_lock); |
|
- | 210 | ||
190 | rwlock_read_unlock(&futex_ht_lock); |
211 | rwlock_read_unlock(&futex_ht_lock); |
191 | } else { |
212 | } else { |
- | 213 | gain_write_access: |
|
192 | /* |
214 | /* |
193 | * Upgrade to writer is not currently supported, |
215 | * Upgrade to writer is not currently supported, |
194 | * therefore, it is necessary to release the read lock |
216 | * therefore, it is necessary to release the read lock |
195 | * and reacquire it as a writer. |
217 | * and reacquire it as a writer. |
196 | */ |
218 | */ |
197 | rwlock_read_unlock(&futex_ht_lock); |
219 | rwlock_read_unlock(&futex_ht_lock); |
198 | 220 | ||
199 | rwlock_write_lock(&futex_ht_lock); |
221 | rwlock_write_lock(&futex_ht_lock); |
200 | /* |
222 | /* |
201 | * Avoid possible race condition by searching |
223 | * Avoid possible race condition by searching |
202 | * the hash table once again with write access. |
224 | * the hash table once again with write access. |
203 | */ |
225 | */ |
204 | item = hash_table_find(&futex_ht, &paddr); |
226 | item = hash_table_find(&futex_ht, &paddr); |
205 | if (item) { |
227 | if (item) { |
206 | futex = hash_table_get_instance(item, futex_t, ht_link); |
228 | futex = hash_table_get_instance(item, futex_t, ht_link); |
- | 229 | ||
- | 230 | /* |
|
- | 231 | * See if this futex is known to the current task. |
|
- | 232 | */ |
|
- | 233 | mutex_lock(&TASK->futexes_lock); |
|
- | 234 | if (!btree_search(&TASK->futexes, paddr, &leaf)) { |
|
- | 235 | /* |
|
- | 236 | * The futex is new to the current task. |
|
- | 237 | * Upgrade its reference count and put it to the |
|
- | 238 | * current task's B+tree of known futexes. |
|
- | 239 | */ |
|
- | 240 | futex->refcount++; |
|
- | 241 | btree_insert(&TASK->futexes, paddr, futex, leaf); |
|
- | 242 | } |
|
- | 243 | mutex_unlock(&TASK->futexes_lock); |
|
- | 244 | ||
207 | rwlock_write_unlock(&futex_ht_lock); |
245 | rwlock_write_unlock(&futex_ht_lock); |
208 | } else { |
246 | } else { |
209 | futex = (futex_t *) malloc(sizeof(futex_t), 0); |
247 | futex = (futex_t *) malloc(sizeof(futex_t), 0); |
210 | futex_initialize(futex); |
248 | futex_initialize(futex); |
211 | futex->paddr = paddr; |
249 | futex->paddr = paddr; |
212 | hash_table_insert(&futex_ht, &paddr, &futex->ht_link); |
250 | hash_table_insert(&futex_ht, &paddr, &futex->ht_link); |
- | 251 | ||
- | 252 | /* |
|
- | 253 | * This is the first task referencing the futex. |
|
- | 254 | * It can be directly inserted into its |
|
- | 255 | * B+tree of known futexes. |
|
- | 256 | */ |
|
- | 257 | mutex_lock(&TASK->futexes_lock); |
|
- | 258 | btree_insert(&TASK->futexes, paddr, futex, NULL); |
|
- | 259 | mutex_unlock(&TASK->futexes_lock); |
|
- | 260 | ||
213 | rwlock_write_unlock(&futex_ht_lock); |
261 | rwlock_write_unlock(&futex_ht_lock); |
214 | } |
262 | } |
215 | } |
263 | } |
216 | 264 | ||
217 | return futex; |
265 | return futex; |
218 | } |
266 | } |
219 | 267 | ||
220 | /** Compute hash index into futex hash table. |
268 | /** Compute hash index into futex hash table. |
221 | * |
269 | * |
222 | * @param key Address where the key (i.e. physical address of futex counter) is stored. |
270 | * @param key Address where the key (i.e. physical address of futex counter) is stored. |
223 | * |
271 | * |
224 | * @return Index into futex hash table. |
272 | * @return Index into futex hash table. |
225 | */ |
273 | */ |
226 | index_t futex_ht_hash(__native *key) |
274 | index_t futex_ht_hash(__native *key) |
227 | { |
275 | { |
228 | return *key & (FUTEX_HT_SIZE-1); |
276 | return *key & (FUTEX_HT_SIZE-1); |
229 | } |
277 | } |
230 | 278 | ||
231 | /** Compare futex hash table item with a key. |
279 | /** Compare futex hash table item with a key. |
232 | * |
280 | * |
233 | * @param key Address where the key (i.e. physical address of futex counter) is stored. |
281 | * @param key Address where the key (i.e. physical address of futex counter) is stored. |
234 | * |
282 | * |
235 | * @return True if the item matches the key. False otherwise. |
283 | * @return True if the item matches the key. False otherwise. |
236 | */ |
284 | */ |
237 | bool futex_ht_compare(__native *key, count_t keys, link_t *item) |
285 | bool futex_ht_compare(__native *key, count_t keys, link_t *item) |
238 | { |
286 | { |
239 | futex_t *futex; |
287 | futex_t *futex; |
240 | 288 | ||
241 | ASSERT(keys == 1); |
289 | ASSERT(keys == 1); |
242 | 290 | ||
243 | futex = hash_table_get_instance(item, futex_t, ht_link); |
291 | futex = hash_table_get_instance(item, futex_t, ht_link); |
244 | return *key == futex->paddr; |
292 | return *key == futex->paddr; |
245 | } |
293 | } |
246 | 294 | ||
247 | /** Callback for removal items from futex hash table. |
295 | /** Callback for removal items from futex hash table. |
248 | * |
296 | * |
249 | * @param item Item removed from the hash table. |
297 | * @param item Item removed from the hash table. |
250 | */ |
298 | */ |
251 | void futex_ht_remove_callback(link_t *item) |
299 | void futex_ht_remove_callback(link_t *item) |
252 | { |
300 | { |
253 | futex_t *futex; |
301 | futex_t *futex; |
254 | 302 | ||
255 | futex = hash_table_get_instance(item, futex_t, ht_link); |
303 | futex = hash_table_get_instance(item, futex_t, ht_link); |
256 | free(futex); |
304 | free(futex); |
257 | } |
305 | } |
258 | 306 |