thr_exit.c revision 297706 
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: head/lib/libthr/thread/thr_exit.c 297706 2016-04-08 11:15:26Z kib $");
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
48void	_pthread_exit(void *status);
49
50static void	exit_thread(void) __dead2;
51
52__weak_reference(_pthread_exit, pthread_exit);
53
54#ifdef _PTHREAD_FORCED_UNWIND
55static int message_printed;
56
57static void thread_unwind(void) __dead2;
58#ifdef PIC
59static void thread_uw_init(void);
60static _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 */
66static _Unwind_Reason_Code (*uwl_forcedunwind)(struct _Unwind_Exception *,
67	_Unwind_Stop_Fn, void *);
68static unsigned long (*uwl_getcfa)(struct _Unwind_Context *);
69
70static void
71thread_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
110unsigned 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
120static void
121thread_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
131static _Unwind_Reason_Code
132thread_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
161static void
162thread_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
174void
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
186void
187_pthread_exit(void *status)
188{
189	_pthread_exit_mask(status, NULL);
190}
191
192void
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 {
246cleanup:
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
262static void
263exit_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