1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1995-1998 John Birrell <[email protected]>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the author nor the names of any co-contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34
35 #include "namespace.h"
36 #include <errno.h>
37 #ifdef _PTHREAD_FORCED_UNWIND
38 #include <dlfcn.h>
39 #endif
40 #include <stdarg.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <pthread.h>
44 #include <sys/types.h>
45 #include <sys/signalvar.h>
46 #include "un-namespace.h"
47
48 #include "libc_private.h"
49 #include "thr_private.h"
50
51 static void exit_thread(void) __dead2;
52
53 __weak_reference(_Tthr_exit, pthread_exit);
54 __weak_reference(_Tthr_exit, _pthread_exit);
55
56 #ifdef _PTHREAD_FORCED_UNWIND
57 static int message_printed;
58
59 static void thread_unwind(void) __dead2;
60 #ifdef PIC
61 static void thread_uw_init(void);
62 static _Unwind_Reason_Code thread_unwind_stop(int version,
63 _Unwind_Action actions,
64 uint64_t exc_class,
65 struct _Unwind_Exception *exc_obj,
66 struct _Unwind_Context *context, void *stop_parameter);
67 /* unwind library pointers */
68 static _Unwind_Reason_Code (*uwl_forcedunwind)(struct _Unwind_Exception *,
69 _Unwind_Stop_Fn, void *);
70 static uintptr_t (*uwl_getcfa)(struct _Unwind_Context *);
71
72 static void
thread_uw_init(void)73 thread_uw_init(void)
74 {
75 static int inited = 0;
76 Dl_info dli;
77 void *handle;
78 void *forcedunwind, *getcfa;
79
80 if (inited)
81 return;
82 handle = RTLD_DEFAULT;
83 if ((forcedunwind = dlsym(handle, "_Unwind_ForcedUnwind")) != NULL) {
84 if (dladdr(forcedunwind, &dli)) {
85 /*
86 * Make sure the address is always valid by holding the library,
87 * also assume functions are in same library.
88 */
89 if ((handle = dlopen(dli.dli_fname, RTLD_LAZY)) != NULL) {
90 forcedunwind = dlsym(handle, "_Unwind_ForcedUnwind");
91 getcfa = dlsym(handle, "_Unwind_GetCFA");
92 if (forcedunwind != NULL && getcfa != NULL) {
93 uwl_getcfa = getcfa;
94 atomic_store_rel_ptr((volatile void *)&uwl_forcedunwind,
95 (uintptr_t)forcedunwind);
96 } else {
97 dlclose(handle);
98 }
99 }
100 }
101 }
102 inited = 1;
103 }
104
105 _Unwind_Reason_Code
_Unwind_ForcedUnwind(struct _Unwind_Exception * ex,_Unwind_Stop_Fn stop_func,void * stop_arg)106 _Unwind_ForcedUnwind(struct _Unwind_Exception *ex, _Unwind_Stop_Fn stop_func,
107 void *stop_arg)
108 {
109 return (*uwl_forcedunwind)(ex, stop_func, stop_arg);
110 }
111
112 uintptr_t
_Unwind_GetCFA(struct _Unwind_Context * context)113 _Unwind_GetCFA(struct _Unwind_Context *context)
114 {
115 return (*uwl_getcfa)(context);
116 }
117 #else
118 #pragma weak _Unwind_GetCFA
119 #pragma weak _Unwind_ForcedUnwind
120 #endif /* PIC */
121
122 static void
thread_unwind_cleanup(_Unwind_Reason_Code code __unused,struct _Unwind_Exception * e __unused)123 thread_unwind_cleanup(_Unwind_Reason_Code code __unused,
124 struct _Unwind_Exception *e __unused)
125 {
126 /*
127 * Specification said that _Unwind_Resume should not be used here,
128 * instead, user should rethrow the exception. For C++ user, they
129 * should put "throw" sentence in catch(...) block.
130 */
131 PANIC("exception should be rethrown");
132 }
133
134 static _Unwind_Reason_Code
thread_unwind_stop(int version __unused,_Unwind_Action actions,uint64_t exc_class __unused,struct _Unwind_Exception * exc_obj __unused,struct _Unwind_Context * context,void * stop_parameter __unused)135 thread_unwind_stop(int version __unused, _Unwind_Action actions,
136 uint64_t exc_class __unused,
137 struct _Unwind_Exception *exc_obj __unused,
138 struct _Unwind_Context *context, void *stop_parameter __unused)
139 {
140 struct pthread *curthread = _get_curthread();
141 struct pthread_cleanup *cur;
142 uintptr_t cfa;
143 int done = 0;
144
145 /* XXX assume stack grows down to lower address */
146
147 cfa = _Unwind_GetCFA(context);
148 if (actions & _UA_END_OF_STACK ||
149 cfa >= (uintptr_t)curthread->unwind_stackend) {
150 done = 1;
151 }
152
153 while ((cur = curthread->cleanup) != NULL &&
154 (done || (uintptr_t)cur <= cfa)) {
155 __pthread_cleanup_pop_imp(1);
156 }
157
158 if (done) {
159 /* Tell libc that it should call non-trivial TLS dtors. */
160 __cxa_thread_call_dtors();
161
162 exit_thread(); /* Never return! */
163 }
164
165 return (_URC_NO_REASON);
166 }
167
168 static void
thread_unwind(void)169 thread_unwind(void)
170 {
171 struct pthread *curthread = _get_curthread();
172
173 curthread->ex.exception_class = 0;
174 curthread->ex.exception_cleanup = thread_unwind_cleanup;
175 _Unwind_ForcedUnwind(&curthread->ex, thread_unwind_stop, NULL);
176 PANIC("_Unwind_ForcedUnwind returned");
177 }
178
179 #endif
180
181 void
_thread_exitf(const char * fname,int lineno,const char * fmt,...)182 _thread_exitf(const char *fname, int lineno, const char *fmt, ...)
183 {
184 va_list ap;
185
186 /* Write an error message to the standard error file descriptor: */
187 _thread_printf(STDERR_FILENO, "Fatal error '");
188
189 va_start(ap, fmt);
190 _thread_vprintf(STDERR_FILENO, fmt, ap);
191 va_end(ap);
192
193 _thread_printf(STDERR_FILENO, "' at line %d in file %s (errno = %d)\n",
194 lineno, fname, errno);
195
196 abort();
197 }
198
199 void
_thread_exit(const char * fname,int lineno,const char * msg)200 _thread_exit(const char *fname, int lineno, const char *msg)
201 {
202
203 _thread_exitf(fname, lineno, "%s", msg);
204 }
205
206 void
_Tthr_exit(void * status)207 _Tthr_exit(void *status)
208 {
209 _pthread_exit_mask(status, NULL);
210 }
211
212 void
_pthread_exit_mask(void * status,sigset_t * mask)213 _pthread_exit_mask(void *status, sigset_t *mask)
214 {
215 struct pthread *curthread = _get_curthread();
216
217 /* Check if this thread is already in the process of exiting: */
218 if (curthread->cancelling)
219 PANIC("Thread %p has called "
220 "pthread_exit() from a destructor. POSIX 1003.1 "
221 "1996 s16.2.5.2 does not allow this!", curthread);
222
223 /* Flag this thread as exiting. */
224 curthread->cancelling = 1;
225 curthread->no_cancel = 1;
226 curthread->cancel_async = 0;
227 curthread->cancel_point = 0;
228 if (mask != NULL)
229 __sys_sigprocmask(SIG_SETMASK, mask, NULL);
230 if (curthread->unblock_sigcancel) {
231 sigset_t set;
232
233 curthread->unblock_sigcancel = 0;
234 SIGEMPTYSET(set);
235 SIGADDSET(set, SIGCANCEL);
236 __sys_sigprocmask(SIG_UNBLOCK, mask, NULL);
237 }
238
239 /* Save the return value: */
240 curthread->ret = status;
241 #ifdef _PTHREAD_FORCED_UNWIND
242
243 #ifdef PIC
244 thread_uw_init();
245 if (uwl_forcedunwind != NULL) {
246 #else
247 if (_Unwind_ForcedUnwind != NULL) {
248 #endif
249 if (curthread->unwind_disabled) {
250 if (message_printed == 0) {
251 message_printed = 1;
252 _thread_printf(2, "Warning: old _pthread_cleanup_push was called, "
253 "stack unwinding is disabled.\n");
254 }
255 goto cleanup;
256 }
257 thread_unwind();
258
259 } else {
260 cleanup:
261 while (curthread->cleanup != NULL) {
262 __pthread_cleanup_pop_imp(1);
263 }
264 __cxa_thread_call_dtors();
265
266 exit_thread();
267 }
268
269 #else
270 while (curthread->cleanup != NULL) {
271 __pthread_cleanup_pop_imp(1);
272 }
273 __cxa_thread_call_dtors();
274
275 exit_thread();
276 #endif /* _PTHREAD_FORCED_UNWIND */
277 }
278
279 static void
280 exit_thread(void)
281 {
282 struct pthread *curthread = _get_curthread();
283
284 free(curthread->name);
285 curthread->name = NULL;
286
287 /* Check if there is thread specific data: */
288 if (curthread->specific != NULL) {
289 /* Run the thread-specific data destructors: */
290 _thread_cleanupspecific();
291 }
292
293 if (!_thr_isthreaded())
294 exit(0);
295
296 if (atomic_fetchadd_int(&_thread_active_threads, -1) == 1) {
297 exit(0);
298 /* Never reach! */
299 }
300
301 /* Tell malloc that the thread is exiting. */
302 _malloc_thread_cleanup();
303
304 THR_LOCK(curthread);
305 curthread->state = PS_DEAD;
306 if (curthread->flags & THR_FLAGS_NEED_SUSPEND) {
307 curthread->cycle++;
308 _thr_umtx_wake(&curthread->cycle, INT_MAX, 0);
309 }
310 if (!curthread->force_exit && SHOULD_REPORT_EVENT(curthread, TD_DEATH))
311 _thr_report_death(curthread);
312 /*
313 * Thread was created with initial refcount 1, we drop the
314 * reference count to allow it to be garbage collected.
315 */
316 curthread->refcount--;
317 _thr_try_gc(curthread, curthread); /* thread lock released */
318
319 #if defined(_PTHREADS_INVARIANTS)
320 if (THR_IN_CRITICAL(curthread))
321 PANIC("thread %p exits with resources held!", curthread);
322 #endif
323 /*
324 * Kernel will do wakeup at the address, so joiner thread
325 * will be resumed if it is sleeping at the address.
326 */
327 thr_exit(&curthread->tid);
328 PANIC("thr_exit() returned");
329 /* Never reach! */
330 }
331