xref: /freebsd/lib/libthr/thread/thr_exit.c (revision 9a14aa017b21c292740c00ee098195cd46642730)
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  * $FreeBSD$
30  */
31 
32 #include "namespace.h"
33 #include <errno.h>
34 #ifdef _PTHREAD_FORCED_UNWIND
35 #include <dlfcn.h>
36 #endif
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <pthread.h>
40 #include <sys/types.h>
41 #include <sys/signalvar.h>
42 #include "un-namespace.h"
43 
44 #include "libc_private.h"
45 #include "thr_private.h"
46 
47 void	_pthread_exit(void *status);
48 
49 static void	exit_thread(void) __dead2;
50 
51 __weak_reference(_pthread_exit, pthread_exit);
52 
53 #ifdef _PTHREAD_FORCED_UNWIND
54 static int message_printed;
55 
56 static void thread_unwind(void) __dead2;
57 #ifdef PIC
58 static void thread_uw_init(void);
59 static _Unwind_Reason_Code thread_unwind_stop(int version,
60 	_Unwind_Action actions,
61 	int64_t exc_class,
62 	struct _Unwind_Exception *exc_obj,
63 	struct _Unwind_Context *context, void *stop_parameter);
64 /* unwind library pointers */
65 static _Unwind_Reason_Code (*uwl_forcedunwind)(struct _Unwind_Exception *,
66 	_Unwind_Stop_Fn, void *);
67 static unsigned long (*uwl_getcfa)(struct _Unwind_Context *);
68 
69 static void
70 thread_uw_init(void)
71 {
72 	static int inited = 0;
73 	Dl_info dlinfo;
74 	void *handle;
75 	void *forcedunwind, *getcfa;
76 
77 	if (inited)
78 	    return;
79 	handle = RTLD_DEFAULT;
80 	if ((forcedunwind = dlsym(handle, "_Unwind_ForcedUnwind")) != NULL) {
81 	    if (dladdr(forcedunwind, &dlinfo)) {
82 		/*
83 		 * Make sure the address is always valid by holding the library,
84 		 * also assume functions are in same library.
85 		 */
86 		if ((handle = dlopen(dlinfo.dli_fname, RTLD_LAZY)) != NULL) {
87 		    forcedunwind = dlsym(handle, "_Unwind_ForcedUnwind");
88 		    getcfa = dlsym(handle, "_Unwind_GetCFA");
89 		    if (forcedunwind != NULL && getcfa != NULL) {
90 			uwl_getcfa = getcfa;
91 			atomic_store_rel_ptr((volatile void *)&uwl_forcedunwind,
92 				(uintptr_t)forcedunwind);
93 		    } else {
94 			dlclose(handle);
95 		    }
96 		}
97 	    }
98 	}
99 	inited = 1;
100 }
101 
102 _Unwind_Reason_Code
103 _Unwind_ForcedUnwind(struct _Unwind_Exception *ex, _Unwind_Stop_Fn stop_func,
104 	void *stop_arg)
105 {
106 	return (*uwl_forcedunwind)(ex, stop_func, stop_arg);
107 }
108 
109 unsigned long
110 _Unwind_GetCFA(struct _Unwind_Context *context)
111 {
112 	return (*uwl_getcfa)(context);
113 }
114 #else
115 #pragma weak _Unwind_GetCFA
116 #pragma weak _Unwind_ForcedUnwind
117 #endif /* PIC */
118 
119 static void
120 thread_unwind_cleanup(_Unwind_Reason_Code code, struct _Unwind_Exception *e)
121 {
122 	/*
123 	 * Specification said that _Unwind_Resume should not be used here,
124 	 * instead, user should rethrow the exception. For C++ user, they
125 	 * should put "throw" sentence in catch(...) block.
126 	 */
127 	PANIC("exception should be rethrown");
128 }
129 
130 static _Unwind_Reason_Code
131 thread_unwind_stop(int version, _Unwind_Action actions,
132 	int64_t exc_class,
133 	struct _Unwind_Exception *exc_obj,
134 	struct _Unwind_Context *context, void *stop_parameter)
135 {
136 	struct pthread *curthread = _get_curthread();
137 	struct pthread_cleanup *cur;
138 	uintptr_t cfa;
139 	int done = 0;
140 
141 	/* XXX assume stack grows down to lower address */
142 
143 	cfa = _Unwind_GetCFA(context);
144 	if (actions & _UA_END_OF_STACK ||
145 	    cfa >= (uintptr_t)curthread->unwind_stackend) {
146 		done = 1;
147 	}
148 
149 	while ((cur = curthread->cleanup) != NULL &&
150 	       (done || (uintptr_t)cur <= cfa)) {
151 		__pthread_cleanup_pop_imp(1);
152 	}
153 
154 	if (done)
155 		exit_thread(); /* Never return! */
156 
157 	return (_URC_NO_REASON);
158 }
159 
160 static void
161 thread_unwind(void)
162 {
163 	struct pthread  *curthread = _get_curthread();
164 
165 	curthread->ex.exception_class = 0;
166 	curthread->ex.exception_cleanup = thread_unwind_cleanup;
167 	_Unwind_ForcedUnwind(&curthread->ex, thread_unwind_stop, NULL);
168 	PANIC("_Unwind_ForcedUnwind returned");
169 }
170 
171 #endif
172 
173 void
174 _thread_exit(const char *fname, int lineno, const char *msg)
175 {
176 
177 	/* Write an error message to the standard error file descriptor: */
178 	_thread_printf(2,
179 	    "Fatal error '%s' at line %d in file %s (errno = %d)\n",
180 	    msg, lineno, fname, errno);
181 
182 	abort();
183 }
184 
185 void
186 _pthread_exit(void *status)
187 {
188 	_pthread_exit_mask(status, NULL);
189 }
190 
191 void
192 _pthread_exit_mask(void *status, sigset_t *mask)
193 {
194 	struct pthread *curthread = _get_curthread();
195 
196 	/* Check if this thread is already in the process of exiting: */
197 	if (curthread->cancelling) {
198 		char msg[128];
199 		snprintf(msg, sizeof(msg), "Thread %p has called "
200 		    "pthread_exit() from a destructor. POSIX 1003.1 "
201 		    "1996 s16.2.5.2 does not allow this!", curthread);
202 		PANIC(msg);
203 	}
204 
205 	/* Flag this thread as exiting. */
206 	curthread->cancelling = 1;
207 	curthread->no_cancel = 1;
208 	curthread->cancel_async = 0;
209 	curthread->cancel_point = 0;
210 	if (mask != NULL)
211 		__sys_sigprocmask(SIG_SETMASK, mask, NULL);
212 	if (curthread->unblock_sigcancel) {
213 		sigset_t set;
214 
215 		curthread->unblock_sigcancel = 0;
216 		SIGEMPTYSET(set);
217 		SIGADDSET(set, SIGCANCEL);
218 		__sys_sigprocmask(SIG_UNBLOCK, mask, NULL);
219 	}
220 
221 	/* Save the return value: */
222 	curthread->ret = status;
223 #ifdef _PTHREAD_FORCED_UNWIND
224 
225 #ifdef PIC
226 	thread_uw_init();
227 #endif /* PIC */
228 
229 #ifdef PIC
230 	if (uwl_forcedunwind != NULL) {
231 #else
232 	if (_Unwind_ForcedUnwind != NULL) {
233 #endif
234 		if (curthread->unwind_disabled) {
235 			if (message_printed == 0) {
236 				message_printed = 1;
237 				_thread_printf(2, "Warning: old _pthread_cleanup_push was called, "
238 				  	"stack unwinding is disabled.\n");
239 			}
240 			goto cleanup;
241 		}
242 		thread_unwind();
243 
244 	} else {
245 cleanup:
246 		while (curthread->cleanup != NULL) {
247 			__pthread_cleanup_pop_imp(1);
248 		}
249 		exit_thread();
250 	}
251 
252 #else
253 	while (curthread->cleanup != NULL) {
254 		__pthread_cleanup_pop_imp(1);
255 	}
256 
257 	exit_thread();
258 #endif /* _PTHREAD_FORCED_UNWIND */
259 }
260 
261 static void
262 exit_thread(void)
263 {
264 	struct pthread *curthread = _get_curthread();
265 
266 	/* Check if there is thread specific data: */
267 	if (curthread->specific != NULL) {
268 		/* Run the thread-specific data destructors: */
269 		_thread_cleanupspecific();
270 	}
271 
272 	if (!_thr_isthreaded())
273 		exit(0);
274 
275 	if (atomic_fetchadd_int(&_thread_active_threads, -1) == 1) {
276 		exit(0);
277 		/* Never reach! */
278 	}
279 
280 	/* Tell malloc that the thread is exiting. */
281 	_malloc_thread_cleanup();
282 
283 	THR_LOCK(curthread);
284 	curthread->state = PS_DEAD;
285 	if (curthread->flags & THR_FLAGS_NEED_SUSPEND) {
286 		curthread->cycle++;
287 		_thr_umtx_wake(&curthread->cycle, INT_MAX, 0);
288 	}
289 	if (!curthread->force_exit && SHOULD_REPORT_EVENT(curthread, TD_DEATH))
290 		_thr_report_death(curthread);
291 	/*
292 	 * Thread was created with initial refcount 1, we drop the
293 	 * reference count to allow it to be garbage collected.
294 	 */
295 	curthread->refcount--;
296 	_thr_try_gc(curthread, curthread); /* thread lock released */
297 
298 #if defined(_PTHREADS_INVARIANTS)
299 	if (THR_IN_CRITICAL(curthread))
300 		PANIC("thread exits with resources held!");
301 #endif
302 	/*
303 	 * Kernel will do wakeup at the address, so joiner thread
304 	 * will be resumed if it is sleeping at the address.
305 	 */
306 	thr_exit(&curthread->tid);
307 	PANIC("thr_exit() returned");
308 	/* Never reach! */
309 }
310