1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
5 * Copyright (C) 2003 Daniel M. Eischen <deischen@freebsd.org>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice unmodified, this list of conditions, and the following
13 * disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30 #include <sys/types.h>
31 #include <sys/queue.h>
32
33 #include <stdlib.h>
34 #include <string.h>
35 #include <pthread.h>
36
37 #include "libc_private.h"
38 #include "thr_private.h"
39 #include "static_tls.h"
40
41 /*#define DEBUG_THREAD_LIST */
42 #ifdef DEBUG_THREAD_LIST
43 #define DBG_MSG stdout_debug
44 #else
45 #define DBG_MSG(x...)
46 #endif
47
48 #define MAX_THREADS 100000
49
50 /*
51 * Define a high water mark for the maximum number of threads that
52 * will be cached. Once this level is reached, any extra threads
53 * will be free()'d.
54 */
55 #define MAX_CACHED_THREADS 100
56
57 /*
58 * We've got to keep track of everything that is allocated, not only
59 * to have a speedy free list, but also so they can be deallocated
60 * after a fork().
61 */
62 static TAILQ_HEAD(, pthread) free_threadq;
63 static struct umutex free_thread_lock = DEFAULT_UMUTEX;
64 static struct umutex tcb_lock = DEFAULT_UMUTEX;
65 static int free_thread_count = 0;
66 static int inited = 0;
67 static int total_threads;
68
69 LIST_HEAD(thread_hash_head, pthread);
70 #define HASH_QUEUES 128
71 static struct thread_hash_head thr_hashtable[HASH_QUEUES];
72 #define THREAD_HASH(thrd) (((unsigned long)thrd >> 8) % HASH_QUEUES)
73
74 static void thr_destroy(struct pthread *curthread, struct pthread *thread);
75
76 void
_thr_list_init(void)77 _thr_list_init(void)
78 {
79 int i;
80
81 _gc_count = 0;
82 total_threads = 1;
83 _thr_urwlock_init(&_thr_list_lock);
84 TAILQ_INIT(&_thread_list);
85 TAILQ_INIT(&free_threadq);
86 _thr_umutex_init(&free_thread_lock);
87 _thr_umutex_init(&tcb_lock);
88 if (inited) {
89 for (i = 0; i < HASH_QUEUES; ++i)
90 LIST_INIT(&thr_hashtable[i]);
91 }
92 inited = 1;
93 }
94
95 void
_thr_gc(struct pthread * curthread)96 _thr_gc(struct pthread *curthread)
97 {
98 struct pthread *td, *td_next;
99 TAILQ_HEAD(, pthread) worklist;
100
101 TAILQ_INIT(&worklist);
102 THREAD_LIST_WRLOCK(curthread);
103
104 /* Check the threads waiting for GC. */
105 TAILQ_FOREACH_SAFE(td, &_thread_gc_list, gcle, td_next) {
106 if (td->tid != TID_TERMINATED) {
107 /* make sure we are not still in userland */
108 continue;
109 }
110 _thr_stack_free(&td->attr);
111 THR_GCLIST_REMOVE(td);
112 TAILQ_INSERT_HEAD(&worklist, td, gcle);
113 }
114 THREAD_LIST_UNLOCK(curthread);
115
116 while ((td = TAILQ_FIRST(&worklist)) != NULL) {
117 TAILQ_REMOVE(&worklist, td, gcle);
118 /*
119 * XXX we don't free initial thread, because there might
120 * have some code referencing initial thread.
121 */
122 if (td == _thr_initial) {
123 DBG_MSG("Initial thread won't be freed\n");
124 continue;
125 }
126
127 _thr_free(curthread, td);
128 }
129 }
130
131 struct pthread *
_thr_alloc(struct pthread * curthread)132 _thr_alloc(struct pthread *curthread)
133 {
134 struct pthread *thread = NULL;
135 struct tcb *tcb;
136
137 if (curthread != NULL) {
138 if (GC_NEEDED())
139 _thr_gc(curthread);
140 if (free_thread_count > 0) {
141 THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
142 if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
143 TAILQ_REMOVE(&free_threadq, thread, tle);
144 free_thread_count--;
145 }
146 THR_LOCK_RELEASE(curthread, &free_thread_lock);
147 }
148 }
149 if (thread == NULL) {
150 if (total_threads > MAX_THREADS)
151 return (NULL);
152 atomic_fetchadd_int(&total_threads, 1);
153 thread = calloc(1, sizeof(struct pthread));
154 if (thread == NULL) {
155 atomic_fetchadd_int(&total_threads, -1);
156 return (NULL);
157 }
158 if ((thread->sleepqueue = _sleepq_alloc()) == NULL ||
159 (thread->wake_addr = _thr_alloc_wake_addr()) == NULL) {
160 thr_destroy(curthread, thread);
161 atomic_fetchadd_int(&total_threads, -1);
162 return (NULL);
163 }
164 } else {
165 bzero(&thread->_pthread_startzero,
166 __rangeof(struct pthread, _pthread_startzero, _pthread_endzero));
167 }
168 if (curthread != NULL) {
169 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
170 tcb = _tcb_ctor(thread, 0 /* not initial tls */);
171 THR_LOCK_RELEASE(curthread, &tcb_lock);
172 } else {
173 tcb = _tcb_ctor(thread, 1 /* initial tls */);
174 }
175 if (tcb != NULL) {
176 thread->tcb = tcb;
177 } else {
178 thr_destroy(curthread, thread);
179 atomic_fetchadd_int(&total_threads, -1);
180 thread = NULL;
181 }
182 return (thread);
183 }
184
185 void
_thr_free(struct pthread * curthread,struct pthread * thread)186 _thr_free(struct pthread *curthread, struct pthread *thread)
187 {
188 DBG_MSG("Freeing thread %p\n", thread);
189
190 /*
191 * Always free tcb, as we only know it is part of RTLD TLS
192 * block, but don't know its detail and can not assume how
193 * it works, so better to avoid caching it here.
194 */
195 if (curthread != NULL) {
196 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
197 _tcb_dtor(thread->tcb);
198 THR_LOCK_RELEASE(curthread, &tcb_lock);
199 } else {
200 _tcb_dtor(thread->tcb);
201 }
202 thread->tcb = NULL;
203 if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
204 thr_destroy(curthread, thread);
205 atomic_fetchadd_int(&total_threads, -1);
206 } else {
207 /*
208 * Add the thread to the free thread list, this also avoids
209 * pthread id is reused too quickly, may help some buggy apps.
210 */
211 THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
212 TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
213 free_thread_count++;
214 THR_LOCK_RELEASE(curthread, &free_thread_lock);
215 }
216 }
217
218 static void
thr_destroy(struct pthread * curthread __unused,struct pthread * thread)219 thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
220 {
221 if (thread->sleepqueue != NULL)
222 _sleepq_free(thread->sleepqueue);
223 if (thread->wake_addr != NULL)
224 _thr_release_wake_addr(thread->wake_addr);
225 free(thread);
226 }
227
228 /*
229 * Add the thread to the list of all threads and increment
230 * number of active threads.
231 */
232 void
_thr_link(struct pthread * curthread,struct pthread * thread)233 _thr_link(struct pthread *curthread, struct pthread *thread)
234 {
235 THREAD_LIST_WRLOCK(curthread);
236 THR_LIST_ADD(thread);
237 THREAD_LIST_UNLOCK(curthread);
238 atomic_add_int(&_thread_active_threads, 1);
239 }
240
241 /*
242 * Remove an active thread.
243 */
244 void
_thr_unlink(struct pthread * curthread,struct pthread * thread)245 _thr_unlink(struct pthread *curthread, struct pthread *thread)
246 {
247 THREAD_LIST_WRLOCK(curthread);
248 THR_LIST_REMOVE(thread);
249 THREAD_LIST_UNLOCK(curthread);
250 atomic_add_int(&_thread_active_threads, -1);
251 }
252
253 void
_thr_hash_add(struct pthread * thread)254 _thr_hash_add(struct pthread *thread)
255 {
256 struct thread_hash_head *head;
257
258 head = &thr_hashtable[THREAD_HASH(thread)];
259 LIST_INSERT_HEAD(head, thread, hle);
260 }
261
262 void
_thr_hash_remove(struct pthread * thread)263 _thr_hash_remove(struct pthread *thread)
264 {
265 LIST_REMOVE(thread, hle);
266 }
267
268 struct pthread *
_thr_hash_find(struct pthread * thread)269 _thr_hash_find(struct pthread *thread)
270 {
271 struct pthread *td;
272 struct thread_hash_head *head;
273
274 head = &thr_hashtable[THREAD_HASH(thread)];
275 LIST_FOREACH(td, head, hle) {
276 if (td == thread)
277 return (thread);
278 }
279 return (NULL);
280 }
281
282 /*
283 * Find a thread in the linked list of active threads and add a reference
284 * to it. Threads with positive reference counts will not be deallocated
285 * until all references are released.
286 */
287 int
_thr_ref_add(struct pthread * curthread,struct pthread * thread,int include_dead)288 _thr_ref_add(struct pthread *curthread, struct pthread *thread,
289 int include_dead)
290 {
291 int ret;
292
293 if (thread == NULL)
294 /* Invalid thread: */
295 return (EINVAL);
296
297 if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
298 thread->refcount++;
299 THR_CRITICAL_ENTER(curthread);
300 THR_THREAD_UNLOCK(curthread, thread);
301 }
302
303 /* Return zero if the thread exists: */
304 return (ret);
305 }
306
307 void
_thr_ref_delete(struct pthread * curthread,struct pthread * thread)308 _thr_ref_delete(struct pthread *curthread, struct pthread *thread)
309 {
310 THR_THREAD_LOCK(curthread, thread);
311 thread->refcount--;
312 _thr_try_gc(curthread, thread);
313 THR_CRITICAL_LEAVE(curthread);
314 }
315
316 /* entered with thread lock held, exit with thread lock released */
317 void
_thr_try_gc(struct pthread * curthread,struct pthread * thread)318 _thr_try_gc(struct pthread *curthread, struct pthread *thread)
319 {
320 if (THR_SHOULD_GC(thread)) {
321 THR_REF_ADD(curthread, thread);
322 THR_THREAD_UNLOCK(curthread, thread);
323 THREAD_LIST_WRLOCK(curthread);
324 THR_THREAD_LOCK(curthread, thread);
325 THR_REF_DEL(curthread, thread);
326 if (THR_SHOULD_GC(thread)) {
327 THR_LIST_REMOVE(thread);
328 THR_GCLIST_ADD(thread);
329 }
330 THR_THREAD_UNLOCK(curthread, thread);
331 THREAD_LIST_UNLOCK(curthread);
332 } else {
333 THR_THREAD_UNLOCK(curthread, thread);
334 }
335 }
336
337 /* return with thread lock held if thread is found */
338 int
_thr_find_thread(struct pthread * curthread,struct pthread * thread,int include_dead)339 _thr_find_thread(struct pthread *curthread, struct pthread *thread,
340 int include_dead)
341 {
342 struct pthread *pthread;
343 int ret;
344
345 if (thread == NULL)
346 return (EINVAL);
347
348 ret = 0;
349 THREAD_LIST_RDLOCK(curthread);
350 pthread = _thr_hash_find(thread);
351 if (pthread) {
352 THR_THREAD_LOCK(curthread, pthread);
353 if (include_dead == 0 && pthread->state == PS_DEAD) {
354 THR_THREAD_UNLOCK(curthread, pthread);
355 ret = ESRCH;
356 }
357 } else {
358 ret = ESRCH;
359 }
360 THREAD_LIST_UNLOCK(curthread);
361 return (ret);
362 }
363
364 #include "pthread_tls.h"
365
366 static void
thr_distribute_static_tls(uintptr_t tlsbase,void * src,size_t len,size_t total_len)367 thr_distribute_static_tls(uintptr_t tlsbase, void *src, size_t len,
368 size_t total_len)
369 {
370
371 memcpy((void *)tlsbase, src, len);
372 memset((char *)tlsbase + len, 0, total_len - len);
373 }
374
375 void
__pthread_distribute_static_tls(size_t offset,void * src,size_t len,size_t total_len)376 __pthread_distribute_static_tls(size_t offset, void *src, size_t len,
377 size_t total_len)
378 {
379 struct pthread *curthread, *thrd;
380 uintptr_t tlsbase;
381
382 if (!_thr_is_inited()) {
383 tlsbase = _libc_get_static_tls_base(offset);
384 thr_distribute_static_tls(tlsbase, src, len, total_len);
385 return;
386 }
387 curthread = _get_curthread();
388 THREAD_LIST_RDLOCK(curthread);
389 TAILQ_FOREACH(thrd, &_thread_list, tle) {
390 tlsbase = _get_static_tls_base(thrd, offset);
391 thr_distribute_static_tls(tlsbase, src, len, total_len);
392 }
393 THREAD_LIST_UNLOCK(curthread);
394 }
395