1 /*
2 * Copyright (c) 2016-2019 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28 /*-
29 * Copyright (c) 1999 Michael Smith <[email protected]>
30 * All rights reserved.
31 *
32 * Redistribution and use in source and binary forms, with or without
33 * modification, are permitted provided that the following conditions
34 * are met:
35 * 1. Redistributions of source code must retain the above copyright
36 * notice, this list of conditions and the following disclaimer.
37 * 2. Redistributions in binary form must reproduce the above copyright
38 * notice, this list of conditions and the following disclaimer in the
39 * documentation and/or other materials provided with the distribution.
40 *
41 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51 * SUCH DAMAGE.
52 */
53
54 #include <sys/cdefs.h>
55 #include <sys/param.h>
56 #include <sys/kernel.h>
57 #include <kern/queue.h>
58 #include <kern/locks.h>
59 #include <sys/malloc.h>
60 #include <sys/proc.h>
61 #include <sys/systm.h>
62 #include <sys/eventhandler.h>
63 #include <sys/sysctl.h>
64 #include <sys/mcache.h> /* for VERIFY() */
65
66 int evh_debug = 0;
67
68 SYSCTL_NODE(_kern, OID_AUTO, eventhandler, CTLFLAG_RW | CTLFLAG_LOCKED,
69 0, "Eventhandler");
70 SYSCTL_INT(_kern_eventhandler, OID_AUTO, debug, CTLFLAG_RW | CTLFLAG_LOCKED,
71 &evh_debug, 0, "Eventhandler debug mode");
72
73 struct eventhandler_entry_arg eventhandler_entry_dummy_arg = { .ee_fm_uuid = { 0 }, .ee_fr_uuid = { 0 } };
74
75 /* List of 'slow' lists */
76 static struct eventhandler_lists_ctxt evthdlr_lists_ctxt_glb;
77 static LCK_GRP_DECLARE(eventhandler_mutex_grp, "eventhandler");
78
79 LCK_GRP_DECLARE(el_lock_grp, "eventhandler list");
80 LCK_ATTR_DECLARE(el_lock_attr, 0, 0);
81
82 struct eventhandler_entry_generic {
83 struct eventhandler_entry ee;
84 void *func;
85 };
86
87 static struct eventhandler_list *_eventhandler_find_list(
88 struct eventhandler_lists_ctxt *evthdlr_lists_ctxt, const char *name);
89
90 void
eventhandler_lists_ctxt_init(struct eventhandler_lists_ctxt * evthdlr_lists_ctxt)91 eventhandler_lists_ctxt_init(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt)
92 {
93 VERIFY(evthdlr_lists_ctxt != NULL);
94
95 TAILQ_INIT(&evthdlr_lists_ctxt->eventhandler_lists);
96 evthdlr_lists_ctxt->eventhandler_lists_initted = 1;
97 lck_mtx_init(&evthdlr_lists_ctxt->eventhandler_mutex,
98 &eventhandler_mutex_grp, LCK_ATTR_NULL);
99 }
100
101 /*
102 * Initialize the eventhandler list.
103 */
104 void
eventhandler_init(void)105 eventhandler_init(void)
106 {
107 eventhandler_lists_ctxt_init(&evthdlr_lists_ctxt_glb);
108 }
109
110 /*
111 * Insertion is O(n) due to the priority scan, but optimises to O(1)
112 * if all priorities are identical.
113 */
114 static eventhandler_tag
eventhandler_register_internal(struct eventhandler_lists_ctxt * evthdlr_lists_ctxt,struct eventhandler_list * list,const char * name,eventhandler_tag epn)115 eventhandler_register_internal(
116 struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
117 struct eventhandler_list *list,
118 const char *name, eventhandler_tag epn)
119 {
120 struct eventhandler_list *new_list;
121 struct eventhandler_entry *ep;
122
123 VERIFY(strlen(name) <= (sizeof(new_list->el_name) - 1));
124
125 if (evthdlr_lists_ctxt == NULL) {
126 evthdlr_lists_ctxt = &evthdlr_lists_ctxt_glb;
127 }
128
129 VERIFY(evthdlr_lists_ctxt->eventhandler_lists_initted); /* eventhandler registered too early */
130 VERIFY(epn != NULL); /* cannot register NULL event */
131
132 /* lock the eventhandler lists */
133 lck_mtx_lock_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
134
135 /* Do we need to find/create the (slow) list? */
136 if (list == NULL) {
137 /* look for a matching, existing list */
138 list = _eventhandler_find_list(evthdlr_lists_ctxt, name);
139
140 /* Do we need to create the list? */
141 if (list == NULL) {
142 lck_mtx_convert_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
143 new_list = kalloc_type(struct eventhandler_list, Z_WAITOK_ZERO);
144 evhlog((LOG_DEBUG, "%s: creating list \"%s\"", __func__, name));
145 list = new_list;
146 list->el_flags = 0;
147 list->el_runcount = 0;
148 bzero(&list->el_lock, sizeof(list->el_lock));
149 (void) snprintf(list->el_name, sizeof(list->el_name), "%s", name);
150 TAILQ_INSERT_HEAD(&evthdlr_lists_ctxt->eventhandler_lists, list, el_link);
151 }
152 }
153 if (!(list->el_flags & EHL_INITTED)) {
154 TAILQ_INIT(&list->el_entries);
155 EHL_LOCK_INIT(list);
156 list->el_flags |= EHL_INITTED;
157 }
158 lck_mtx_unlock(&evthdlr_lists_ctxt->eventhandler_mutex);
159
160 KASSERT(epn->ee_priority != EHE_DEAD_PRIORITY,
161 ("%s: handler for %s registered with dead priority", __func__, name));
162
163 /* sort it into the list */
164 evhlog((LOG_DEBUG, "%s: adding item %p (function %p to \"%s\"", __func__, (void *)VM_KERNEL_ADDRPERM(epn),
165 (void *)VM_KERNEL_UNSLIDE(((struct eventhandler_entry_generic *)epn)->func), name));
166 EHL_LOCK(list);
167 TAILQ_FOREACH(ep, &list->el_entries, ee_link) {
168 if (ep->ee_priority != EHE_DEAD_PRIORITY &&
169 epn->ee_priority < ep->ee_priority) {
170 TAILQ_INSERT_BEFORE(ep, epn, ee_link);
171 break;
172 }
173 }
174 if (ep == NULL) {
175 TAILQ_INSERT_TAIL(&list->el_entries, epn, ee_link);
176 }
177 EHL_UNLOCK(list);
178 return epn;
179 }
180
181 eventhandler_tag
eventhandler_register(struct eventhandler_lists_ctxt * evthdlr_lists_ctxt,struct eventhandler_list * list,const char * name,void * func,struct eventhandler_entry_arg arg,int priority)182 eventhandler_register(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
183 struct eventhandler_list *list, const char *name,
184 void *func, struct eventhandler_entry_arg arg, int priority)
185 {
186 struct eventhandler_entry_generic *eg;
187
188 /* allocate an entry for this handler, populate it */
189 eg = kalloc_type(struct eventhandler_entry_generic, Z_WAITOK_ZERO);
190 eg->func = func;
191 eg->ee.ee_arg = arg;
192 eg->ee.ee_priority = priority;
193
194 return eventhandler_register_internal(evthdlr_lists_ctxt, list, name, &eg->ee);
195 }
196
197 void
eventhandler_deregister(struct eventhandler_list * list,eventhandler_tag tag)198 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
199 {
200 struct eventhandler_entry *ep = tag;
201
202 EHL_LOCK_ASSERT(list, LCK_MTX_ASSERT_OWNED);
203 if (ep != NULL) {
204 /* remove just this entry */
205 if (list->el_runcount == 0) {
206 evhlog((LOG_DEBUG, "%s: removing item %p from \"%s\"", __func__, (void *)VM_KERNEL_ADDRPERM(ep),
207 list->el_name));
208 /*
209 * We may have purged the list because of certain events.
210 * Make sure that is not the case when a specific entry
211 * is being removed.
212 */
213 if (!TAILQ_EMPTY(&list->el_entries)) {
214 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
215 }
216 EHL_LOCK_CONVERT(list);
217 kfree_type(struct eventhandler_entry, ep);
218 } else {
219 evhlog((LOG_DEBUG, "%s: marking item %p from \"%s\" as dead", __func__,
220 (void *)VM_KERNEL_ADDRPERM(ep), list->el_name));
221 ep->ee_priority = EHE_DEAD_PRIORITY;
222 }
223 } else {
224 /* remove entire list */
225 if (list->el_runcount == 0) {
226 evhlog((LOG_DEBUG, "%s: removing all items from \"%s\"", __func__,
227 list->el_name));
228 EHL_LOCK_CONVERT(list);
229 while (!TAILQ_EMPTY(&list->el_entries)) {
230 ep = TAILQ_FIRST(&list->el_entries);
231 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
232 kfree_type(struct eventhandler_entry, ep);
233 }
234 } else {
235 evhlog((LOG_DEBUG, "%s: marking all items from \"%s\" as dead",
236 __func__, list->el_name));
237 TAILQ_FOREACH(ep, &list->el_entries, ee_link)
238 ep->ee_priority = EHE_DEAD_PRIORITY;
239 }
240 }
241 while (list->el_runcount > 0) {
242 msleep((caddr_t)list, &list->el_lock, PSPIN, "evhrm", 0);
243 }
244 EHL_UNLOCK(list);
245 }
246
247 /*
248 * Internal version for use when eventhandler list is already locked.
249 */
250 static struct eventhandler_list *
_eventhandler_find_list(struct eventhandler_lists_ctxt * evthdlr_lists_ctxt,const char * name)251 _eventhandler_find_list(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
252 const char *name)
253 {
254 struct eventhandler_list *list;
255
256 VERIFY(evthdlr_lists_ctxt != NULL);
257
258 LCK_MTX_ASSERT(&evthdlr_lists_ctxt->eventhandler_mutex, LCK_MTX_ASSERT_OWNED);
259 TAILQ_FOREACH(list, &evthdlr_lists_ctxt->eventhandler_lists, el_link) {
260 if (!strcmp(name, list->el_name)) {
261 break;
262 }
263 }
264 return list;
265 }
266
267 /*
268 * Lookup a "slow" list by name. Returns with the list locked.
269 */
270 struct eventhandler_list *
eventhandler_find_list(struct eventhandler_lists_ctxt * evthdlr_lists_ctxt,const char * name)271 eventhandler_find_list(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
272 const char *name)
273 {
274 struct eventhandler_list *list;
275
276 if (evthdlr_lists_ctxt == NULL) {
277 evthdlr_lists_ctxt = &evthdlr_lists_ctxt_glb;
278 }
279
280 if (!evthdlr_lists_ctxt->eventhandler_lists_initted) {
281 return NULL;
282 }
283
284 /* scan looking for the requested list */
285 lck_mtx_lock_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
286 list = _eventhandler_find_list(evthdlr_lists_ctxt, name);
287 if (list != NULL) {
288 lck_mtx_convert_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
289 EHL_LOCK_SPIN(list);
290 }
291 lck_mtx_unlock(&evthdlr_lists_ctxt->eventhandler_mutex);
292
293 return list;
294 }
295
296 /*
297 * Prune "dead" entries from an eventhandler list.
298 */
299 void
eventhandler_prune_list(struct eventhandler_list * list)300 eventhandler_prune_list(struct eventhandler_list *list)
301 {
302 struct eventhandler_entry *ep, *en;
303 int pruned = 0;
304
305 evhlog((LOG_DEBUG, "%s: pruning list \"%s\"", __func__, list->el_name));
306 EHL_LOCK_ASSERT(list, LCK_MTX_ASSERT_OWNED);
307 TAILQ_FOREACH_SAFE(ep, &list->el_entries, ee_link, en) {
308 if (ep->ee_priority == EHE_DEAD_PRIORITY) {
309 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
310 kfree_type(struct eventhandler_entry, ep);
311 pruned++;
312 }
313 }
314 if (pruned > 0) {
315 wakeup(list);
316 }
317 }
318
319 /*
320 * This should be called when last reference to an object
321 * is being released.
322 * The individual event type lists must be purged when the object
323 * becomes defunct.
324 */
325 void
eventhandler_lists_ctxt_destroy(struct eventhandler_lists_ctxt * evthdlr_lists_ctxt)326 eventhandler_lists_ctxt_destroy(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt)
327 {
328 struct eventhandler_list *list = NULL;
329 struct eventhandler_list *list_next = NULL;
330
331 lck_mtx_lock(&evthdlr_lists_ctxt->eventhandler_mutex);
332 TAILQ_FOREACH_SAFE(list, &evthdlr_lists_ctxt->eventhandler_lists,
333 el_link, list_next) {
334 VERIFY(TAILQ_EMPTY(&list->el_entries));
335 EHL_LOCK_DESTROY(list);
336 kfree_type(struct eventhandler_list, list);
337 }
338 lck_mtx_unlock(&evthdlr_lists_ctxt->eventhandler_mutex);
339 lck_mtx_destroy(&evthdlr_lists_ctxt->eventhandler_mutex,
340 &eventhandler_mutex_grp);
341 return;
342 }
343