xref: /freebsd/lib/libthr/thread/thr_exit.c (revision d9f0ce31900a48d1a2bfc1c8c86f79d1e831451a)
1 /*
2  * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the author nor the names of any co-contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32 
33 #include "namespace.h"
34 #include <errno.h>
35 #ifdef _PTHREAD_FORCED_UNWIND
36 #include <dlfcn.h>
37 #endif
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <pthread.h>
41 #include <sys/types.h>
42 #include <sys/signalvar.h>
43 #include "un-namespace.h"
44 
45 #include "libc_private.h"
46 #include "thr_private.h"
47 
48 void	_pthread_exit(void *status);
49 
50 static void	exit_thread(void) __dead2;
51 
52 __weak_reference(_pthread_exit, pthread_exit);
53 
54 #ifdef _PTHREAD_FORCED_UNWIND
55 static int message_printed;
56 
57 static void thread_unwind(void) __dead2;
58 #ifdef PIC
59 static void thread_uw_init(void);
60 static _Unwind_Reason_Code thread_unwind_stop(int version,
61 	_Unwind_Action actions,
62 	int64_t exc_class,
63 	struct _Unwind_Exception *exc_obj,
64 	struct _Unwind_Context *context, void *stop_parameter);
65 /* unwind library pointers */
66 static _Unwind_Reason_Code (*uwl_forcedunwind)(struct _Unwind_Exception *,
67 	_Unwind_Stop_Fn, void *);
68 static unsigned long (*uwl_getcfa)(struct _Unwind_Context *);
69 
70 static void
71 thread_uw_init(void)
72 {
73 	static int inited = 0;
74 	Dl_info dlinfo;
75 	void *handle;
76 	void *forcedunwind, *getcfa;
77 
78 	if (inited)
79 	    return;
80 	handle = RTLD_DEFAULT;
81 	if ((forcedunwind = dlsym(handle, "_Unwind_ForcedUnwind")) != NULL) {
82 	    if (dladdr(forcedunwind, &dlinfo)) {
83 		/*
84 		 * Make sure the address is always valid by holding the library,
85 		 * also assume functions are in same library.
86 		 */
87 		if ((handle = dlopen(dlinfo.dli_fname, RTLD_LAZY)) != NULL) {
88 		    forcedunwind = dlsym(handle, "_Unwind_ForcedUnwind");
89 		    getcfa = dlsym(handle, "_Unwind_GetCFA");
90 		    if (forcedunwind != NULL && getcfa != NULL) {
91 			uwl_getcfa = getcfa;
92 			atomic_store_rel_ptr((volatile void *)&uwl_forcedunwind,
93 				(uintptr_t)forcedunwind);
94 		    } else {
95 			dlclose(handle);
96 		    }
97 		}
98 	    }
99 	}
100 	inited = 1;
101 }
102 
103 _Unwind_Reason_Code
104 _Unwind_ForcedUnwind(struct _Unwind_Exception *ex, _Unwind_Stop_Fn stop_func,
105 	void *stop_arg)
106 {
107 	return (*uwl_forcedunwind)(ex, stop_func, stop_arg);
108 }
109 
110 unsigned long
111 _Unwind_GetCFA(struct _Unwind_Context *context)
112 {
113 	return (*uwl_getcfa)(context);
114 }
115 #else
116 #pragma weak _Unwind_GetCFA
117 #pragma weak _Unwind_ForcedUnwind
118 #endif /* PIC */
119 
120 static void
121 thread_unwind_cleanup(_Unwind_Reason_Code code, struct _Unwind_Exception *e)
122 {
123 	/*
124 	 * Specification said that _Unwind_Resume should not be used here,
125 	 * instead, user should rethrow the exception. For C++ user, they
126 	 * should put "throw" sentence in catch(...) block.
127 	 */
128 	PANIC("exception should be rethrown");
129 }
130 
131 static _Unwind_Reason_Code
132 thread_unwind_stop(int version, _Unwind_Action actions,
133 	int64_t exc_class,
134 	struct _Unwind_Exception *exc_obj,
135 	struct _Unwind_Context *context, void *stop_parameter)
136 {
137 	struct pthread *curthread = _get_curthread();
138 	struct pthread_cleanup *cur;
139 	uintptr_t cfa;
140 	int done = 0;
141 
142 	/* XXX assume stack grows down to lower address */
143 
144 	cfa = _Unwind_GetCFA(context);
145 	if (actions & _UA_END_OF_STACK ||
146 	    cfa >= (uintptr_t)curthread->unwind_stackend) {
147 		done = 1;
148 	}
149 
150 	while ((cur = curthread->cleanup) != NULL &&
151 	       (done || (uintptr_t)cur <= cfa)) {
152 		__pthread_cleanup_pop_imp(1);
153 	}
154 
155 	if (done)
156 		exit_thread(); /* Never return! */
157 
158 	return (_URC_NO_REASON);
159 }
160 
161 static void
162 thread_unwind(void)
163 {
164 	struct pthread  *curthread = _get_curthread();
165 
166 	curthread->ex.exception_class = 0;
167 	curthread->ex.exception_cleanup = thread_unwind_cleanup;
168 	_Unwind_ForcedUnwind(&curthread->ex, thread_unwind_stop, NULL);
169 	PANIC("_Unwind_ForcedUnwind returned");
170 }
171 
172 #endif
173 
174 void
175 _thread_exit(const char *fname, int lineno, const char *msg)
176 {
177 
178 	/* Write an error message to the standard error file descriptor: */
179 	_thread_printf(2,
180 	    "Fatal error '%s' at line %d in file %s (errno = %d)\n",
181 	    msg, lineno, fname, errno);
182 
183 	abort();
184 }
185 
186 void
187 _pthread_exit(void *status)
188 {
189 	_pthread_exit_mask(status, NULL);
190 }
191 
192 void
193 _pthread_exit_mask(void *status, sigset_t *mask)
194 {
195 	struct pthread *curthread = _get_curthread();
196 
197 	/* Check if this thread is already in the process of exiting: */
198 	if (curthread->cancelling) {
199 		char msg[128];
200 		snprintf(msg, sizeof(msg), "Thread %p has called "
201 		    "pthread_exit() from a destructor. POSIX 1003.1 "
202 		    "1996 s16.2.5.2 does not allow this!", curthread);
203 		PANIC(msg);
204 	}
205 
206 	/* Flag this thread as exiting. */
207 	curthread->cancelling = 1;
208 	curthread->no_cancel = 1;
209 	curthread->cancel_async = 0;
210 	curthread->cancel_point = 0;
211 	if (mask != NULL)
212 		__sys_sigprocmask(SIG_SETMASK, mask, NULL);
213 	if (curthread->unblock_sigcancel) {
214 		sigset_t set;
215 
216 		curthread->unblock_sigcancel = 0;
217 		SIGEMPTYSET(set);
218 		SIGADDSET(set, SIGCANCEL);
219 		__sys_sigprocmask(SIG_UNBLOCK, mask, NULL);
220 	}
221 
222 	/* Save the return value: */
223 	curthread->ret = status;
224 #ifdef _PTHREAD_FORCED_UNWIND
225 
226 #ifdef PIC
227 	thread_uw_init();
228 #endif /* PIC */
229 
230 #ifdef PIC
231 	if (uwl_forcedunwind != NULL) {
232 #else
233 	if (_Unwind_ForcedUnwind != NULL) {
234 #endif
235 		if (curthread->unwind_disabled) {
236 			if (message_printed == 0) {
237 				message_printed = 1;
238 				_thread_printf(2, "Warning: old _pthread_cleanup_push was called, "
239 				  	"stack unwinding is disabled.\n");
240 			}
241 			goto cleanup;
242 		}
243 		thread_unwind();
244 
245 	} else {
246 cleanup:
247 		while (curthread->cleanup != NULL) {
248 			__pthread_cleanup_pop_imp(1);
249 		}
250 		exit_thread();
251 	}
252 
253 #else
254 	while (curthread->cleanup != NULL) {
255 		__pthread_cleanup_pop_imp(1);
256 	}
257 
258 	exit_thread();
259 #endif /* _PTHREAD_FORCED_UNWIND */
260 }
261 
262 static void
263 exit_thread(void)
264 {
265 	struct pthread *curthread = _get_curthread();
266 
267 	/* Check if there is thread specific data: */
268 	if (curthread->specific != NULL) {
269 		/* Run the thread-specific data destructors: */
270 		_thread_cleanupspecific();
271 	}
272 
273 	if (!_thr_isthreaded())
274 		exit(0);
275 
276 	if (atomic_fetchadd_int(&_thread_active_threads, -1) == 1) {
277 		exit(0);
278 		/* Never reach! */
279 	}
280 
281 	/* Tell malloc that the thread is exiting. */
282 	_malloc_thread_cleanup();
283 
284 	THR_LOCK(curthread);
285 	curthread->state = PS_DEAD;
286 	if (curthread->flags & THR_FLAGS_NEED_SUSPEND) {
287 		curthread->cycle++;
288 		_thr_umtx_wake(&curthread->cycle, INT_MAX, 0);
289 	}
290 	if (!curthread->force_exit && SHOULD_REPORT_EVENT(curthread, TD_DEATH))
291 		_thr_report_death(curthread);
292 	/*
293 	 * Thread was created with initial refcount 1, we drop the
294 	 * reference count to allow it to be garbage collected.
295 	 */
296 	curthread->refcount--;
297 	_thr_try_gc(curthread, curthread); /* thread lock released */
298 
299 #if defined(_PTHREADS_INVARIANTS)
300 	if (THR_IN_CRITICAL(curthread))
301 		PANIC("thread exits with resources held!");
302 #endif
303 	/*
304 	 * Kernel will do wakeup at the address, so joiner thread
305 	 * will be resumed if it is sleeping at the address.
306 	 */
307 	thr_exit(&curthread->tid);
308 	PANIC("thr_exit() returned");
309 	/* Never reach! */
310 }
311