1/* Copyright (C) 2002-2018 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#include <assert.h>
20#include <errno.h>
21#include <limits.h>
22#include <signal.h>
23#include <stdlib.h>
24#include <unistd.h>
25#include <sys/param.h>
26#include <sys/resource.h>
27#include <pthreadP.h>
28#include <atomic.h>
29#include <ldsodefs.h>
30#include <tls.h>
31#include <list.h>
32#include <fork.h>
33#include <version.h>
34#include <shlib-compat.h>
35#include <smp.h>
36#include <lowlevellock.h>
37#include <futex-internal.h>
38#include <kernel-features.h>
39#include <libc-pointer-arith.h>
40#include <pthread-pids.h>
41
42#ifndef TLS_MULTIPLE_THREADS_IN_TCB
43/* Pointer to the corresponding variable in libc. */
44int *__libc_multiple_threads_ptr attribute_hidden;
45#endif
46
47/* Size and alignment of static TLS block. */
48size_t __static_tls_size;
49size_t __static_tls_align_m1;
50
51#ifndef __ASSUME_SET_ROBUST_LIST
52/* Negative if we do not have the system call and we can use it. */
53int __set_robust_list_avail;
54# define set_robust_list_not_avail() \
55 __set_robust_list_avail = -1
56#else
57# define set_robust_list_not_avail() do { } while (0)
58#endif
59
60#ifndef __ASSUME_FUTEX_CLOCK_REALTIME
61/* Nonzero if we do not have FUTEX_CLOCK_REALTIME. */
62int __have_futex_clock_realtime;
63# define __set_futex_clock_realtime() \
64 __have_futex_clock_realtime = 1
65#else
66#define __set_futex_clock_realtime() do { } while (0)
67#endif
68
69/* Version of the library, used in libthread_db to detect mismatches. */
70static const char nptl_version[] __attribute_used__ = VERSION;
71
72
73#ifdef SHARED
74static
75#else
76extern
77#endif
78void __nptl_set_robust (struct pthread *);
79
80#ifdef SHARED
81static void nptl_freeres (void);
82
83
84static const struct pthread_functions pthread_functions =
85 {
86 .ptr_pthread_attr_destroy = __pthread_attr_destroy,
87# if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
88 .ptr___pthread_attr_init_2_0 = __pthread_attr_init_2_0,
89# endif
90 .ptr___pthread_attr_init_2_1 = __pthread_attr_init_2_1,
91 .ptr_pthread_attr_getdetachstate = __pthread_attr_getdetachstate,
92 .ptr_pthread_attr_setdetachstate = __pthread_attr_setdetachstate,
93 .ptr_pthread_attr_getinheritsched = __pthread_attr_getinheritsched,
94 .ptr_pthread_attr_setinheritsched = __pthread_attr_setinheritsched,
95 .ptr_pthread_attr_getschedparam = __pthread_attr_getschedparam,
96 .ptr_pthread_attr_setschedparam = __pthread_attr_setschedparam,
97 .ptr_pthread_attr_getschedpolicy = __pthread_attr_getschedpolicy,
98 .ptr_pthread_attr_setschedpolicy = __pthread_attr_setschedpolicy,
99 .ptr_pthread_attr_getscope = __pthread_attr_getscope,
100 .ptr_pthread_attr_setscope = __pthread_attr_setscope,
101 .ptr_pthread_condattr_destroy = __pthread_condattr_destroy,
102 .ptr_pthread_condattr_init = __pthread_condattr_init,
103 .ptr___pthread_cond_broadcast = __pthread_cond_broadcast,
104 .ptr___pthread_cond_destroy = __pthread_cond_destroy,
105 .ptr___pthread_cond_init = __pthread_cond_init,
106 .ptr___pthread_cond_signal = __pthread_cond_signal,
107 .ptr___pthread_cond_wait = __pthread_cond_wait,
108 .ptr___pthread_cond_timedwait = __pthread_cond_timedwait,
109# if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_3_2)
110 .ptr___pthread_cond_broadcast_2_0 = __pthread_cond_broadcast_2_0,
111 .ptr___pthread_cond_destroy_2_0 = __pthread_cond_destroy_2_0,
112 .ptr___pthread_cond_init_2_0 = __pthread_cond_init_2_0,
113 .ptr___pthread_cond_signal_2_0 = __pthread_cond_signal_2_0,
114 .ptr___pthread_cond_wait_2_0 = __pthread_cond_wait_2_0,
115 .ptr___pthread_cond_timedwait_2_0 = __pthread_cond_timedwait_2_0,
116# endif
117 .ptr_pthread_equal = __pthread_equal,
118 .ptr___pthread_exit = __pthread_exit,
119 .ptr_pthread_getschedparam = __pthread_getschedparam,
120 .ptr_pthread_setschedparam = __pthread_setschedparam,
121 .ptr_pthread_mutex_destroy = __pthread_mutex_destroy,
122 .ptr_pthread_mutex_init = __pthread_mutex_init,
123 .ptr_pthread_mutex_lock = __pthread_mutex_lock,
124 .ptr_pthread_mutex_unlock = __pthread_mutex_unlock,
125 .ptr___pthread_setcancelstate = __pthread_setcancelstate,
126 .ptr_pthread_setcanceltype = __pthread_setcanceltype,
127 .ptr___pthread_cleanup_upto = __pthread_cleanup_upto,
128 .ptr___pthread_once = __pthread_once,
129 .ptr___pthread_rwlock_rdlock = __pthread_rwlock_rdlock,
130 .ptr___pthread_rwlock_wrlock = __pthread_rwlock_wrlock,
131 .ptr___pthread_rwlock_unlock = __pthread_rwlock_unlock,
132 .ptr___pthread_key_create = __pthread_key_create,
133 .ptr___pthread_getspecific = __pthread_getspecific,
134 .ptr___pthread_setspecific = __pthread_setspecific,
135 .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer,
136 .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore,
137 .ptr_nthreads = &__nptl_nthreads,
138 .ptr___pthread_unwind = &__pthread_unwind,
139 .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd,
140# ifdef SIGSETXID
141 .ptr__nptl_setxid = __nptl_setxid,
142# endif
143 /* For now only the stack cache needs to be freed. */
144 .ptr_freeres = nptl_freeres,
145 .ptr_set_robust = __nptl_set_robust
146 };
147# define ptr_pthread_functions &pthread_functions
148#else
149# define ptr_pthread_functions NULL
150#endif
151
152
153#ifdef SHARED
154/* This function is called indirectly from the freeres code in libc. */
155static void
156__libc_freeres_fn_section
157nptl_freeres (void)
158{
159 __unwind_freeres ();
160 __free_stacks (0);
161}
162
163
164static
165#endif
166void
167__nptl_set_robust (struct pthread *self)
168{
169#ifdef __NR_set_robust_list
170 INTERNAL_SYSCALL_DECL (err);
171 INTERNAL_SYSCALL (set_robust_list, err, 2, &self->robust_head,
172 sizeof (struct robust_list_head));
173#endif
174}
175
176
177#ifdef SIGCANCEL
178/* For asynchronous cancellation we use a signal. This is the handler. */
179static void
180sigcancel_handler (int sig, siginfo_t *si, void *ctx)
181{
182 /* Safety check. It would be possible to call this function for
183 other signals and send a signal from another process. This is not
184 correct and might even be a security problem. Try to catch as
185 many incorrect invocations as possible. */
186 if (sig != SIGCANCEL
187 || si->si_pid != __getpid()
188 || si->si_code != SI_TKILL)
189 return;
190
191 struct pthread *self = THREAD_SELF;
192
193 int oldval = THREAD_GETMEM (self, cancelhandling);
194 while (1)
195 {
196 /* We are canceled now. When canceled by another thread this flag
197 is already set but if the signal is directly send (internally or
198 from another process) is has to be done here. */
199 int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
200
201 if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
202 /* Already canceled or exiting. */
203 break;
204
205 int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
206 oldval);
207 if (curval == oldval)
208 {
209 /* Set the return value. */
210 THREAD_SETMEM (self, result, PTHREAD_CANCELED);
211
212 /* Make sure asynchronous cancellation is still enabled. */
213 if ((newval & CANCELTYPE_BITMASK) != 0)
214 /* Run the registered destructors and terminate the thread. */
215 __do_cancel ();
216
217 break;
218 }
219
220 oldval = curval;
221 }
222}
223#endif
224
225
226#ifdef SIGSETXID
227struct xid_command *__xidcmd attribute_hidden;
228
229/* We use the SIGSETXID signal in the setuid, setgid, etc. implementations to
230 tell each thread to call the respective setxid syscall on itself. This is
231 the handler. */
232static void
233sighandler_setxid (int sig, siginfo_t *si, void *ctx)
234{
235 int result;
236
237 /* Safety check. It would be possible to call this function for
238 other signals and send a signal from another process. This is not
239 correct and might even be a security problem. Try to catch as
240 many incorrect invocations as possible. */
241 if (sig != SIGSETXID
242 || si->si_pid != __getpid ()
243 || si->si_code != SI_TKILL)
244 return;
245
246 INTERNAL_SYSCALL_DECL (err);
247 result = INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
248 __xidcmd->id[1], __xidcmd->id[2]);
249 int error = 0;
250 if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
251 error = INTERNAL_SYSCALL_ERRNO (result, err);
252 __nptl_setxid_error (__xidcmd, error);
253
254 /* Reset the SETXID flag. */
255 struct pthread *self = THREAD_SELF;
256 int flags, newval;
257 do
258 {
259 flags = THREAD_GETMEM (self, cancelhandling);
260 newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
261 flags & ~SETXID_BITMASK, flags);
262 }
263 while (flags != newval);
264
265 /* And release the futex. */
266 self->setxid_futex = 1;
267 futex_wake (&self->setxid_futex, 1, FUTEX_PRIVATE);
268
269 if (atomic_decrement_val (&__xidcmd->cntr) == 0)
270 futex_wake ((unsigned int *) &__xidcmd->cntr, 1, FUTEX_PRIVATE);
271}
272#endif
273
274
275/* When using __thread for this, we do it in libc so as not
276 to give libpthread its own TLS segment just for this. */
277extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
278
279
280/* This can be set by the debugger before initialization is complete. */
281static bool __nptl_initial_report_events __attribute_used__;
282
283void
284__pthread_initialize_minimal_internal (void)
285{
286 /* Minimal initialization of the thread descriptor. */
287 struct pthread *pd = THREAD_SELF;
288 __pthread_initialize_pids (pd);
289 THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
290 THREAD_SETMEM (pd, user_stack, true);
291 if (LLL_LOCK_INITIALIZER != 0)
292 THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
293#if HP_TIMING_AVAIL
294 THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
295#endif
296
297 /* Initialize the robust mutex data. */
298 {
299#if __PTHREAD_MUTEX_HAVE_PREV
300 pd->robust_prev = &pd->robust_head;
301#endif
302 pd->robust_head.list = &pd->robust_head;
303#ifdef __NR_set_robust_list
304 pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
305 - offsetof (pthread_mutex_t,
306 __data.__list.__next));
307 INTERNAL_SYSCALL_DECL (err);
308 int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
309 sizeof (struct robust_list_head));
310 if (INTERNAL_SYSCALL_ERROR_P (res, err))
311#endif
312 set_robust_list_not_avail ();
313 }
314
315#ifdef __NR_futex
316# ifndef __ASSUME_PRIVATE_FUTEX
317 /* Private futexes are always used (at least internally) so that
318 doing the test once this early is beneficial. */
319 {
320 int word = 0;
321 INTERNAL_SYSCALL_DECL (err);
322 word = INTERNAL_SYSCALL (futex, err, 3, &word,
323 FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1);
324 if (!INTERNAL_SYSCALL_ERROR_P (word, err))
325 THREAD_SETMEM (pd, header.private_futex, FUTEX_PRIVATE_FLAG);
326 }
327
328 /* Private futexes have been introduced earlier than the
329 FUTEX_CLOCK_REALTIME flag. We don't have to run the test if we
330 know the former are not supported. This also means we know the
331 kernel will return ENOSYS for unknown operations. */
332 if (THREAD_GETMEM (pd, header.private_futex) != 0)
333# endif
334# ifndef __ASSUME_FUTEX_CLOCK_REALTIME
335 {
336 int word = 0;
337 /* NB: the syscall actually takes six parameters. The last is the
338 bit mask. But since we will not actually wait at all the value
339 is irrelevant. Given that passing six parameters is difficult
340 on some architectures we just pass whatever random value the
341 calling convention calls for to the kernel. It causes no harm. */
342 INTERNAL_SYSCALL_DECL (err);
343 word = INTERNAL_SYSCALL (futex, err, 5, &word,
344 FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME
345 | FUTEX_PRIVATE_FLAG, 1, NULL, 0);
346 assert (INTERNAL_SYSCALL_ERROR_P (word, err));
347 if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS)
348 __set_futex_clock_realtime ();
349 }
350# endif
351#endif
352
353 /* Set initial thread's stack block from 0 up to __libc_stack_end.
354 It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
355 purposes this is good enough. */
356 THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
357
358 /* Initialize the list of all running threads with the main thread. */
359 INIT_LIST_HEAD (&__stack_user);
360 list_add (&pd->list, &__stack_user);
361
362 /* Before initializing __stack_user, the debugger could not find us and
363 had to set __nptl_initial_report_events. Propagate its setting. */
364 THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
365
366#if defined SIGCANCEL || defined SIGSETXID
367 struct sigaction sa;
368 __sigemptyset (&sa.sa_mask);
369
370# ifdef SIGCANCEL
371 /* Install the cancellation signal handler. If for some reason we
372 cannot install the handler we do not abort. Maybe we should, but
373 it is only asynchronous cancellation which is affected. */
374 sa.sa_sigaction = sigcancel_handler;
375 sa.sa_flags = SA_SIGINFO;
376 (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
377# endif
378
379# ifdef SIGSETXID
380 /* Install the handle to change the threads' uid/gid. */
381 sa.sa_sigaction = sighandler_setxid;
382 sa.sa_flags = SA_SIGINFO | SA_RESTART;
383 (void) __libc_sigaction (SIGSETXID, &sa, NULL);
384# endif
385
386 /* The parent process might have left the signals blocked. Just in
387 case, unblock it. We reuse the signal mask in the sigaction
388 structure. It is already cleared. */
389# ifdef SIGCANCEL
390 __sigaddset (&sa.sa_mask, SIGCANCEL);
391# endif
392# ifdef SIGSETXID
393 __sigaddset (&sa.sa_mask, SIGSETXID);
394# endif
395 {
396 INTERNAL_SYSCALL_DECL (err);
397 (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
398 NULL, _NSIG / 8);
399 }
400#endif
401
402 /* Get the size of the static and alignment requirements for the TLS
403 block. */
404 size_t static_tls_align;
405 _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
406
407 /* Make sure the size takes all the alignments into account. */
408 if (STACK_ALIGN > static_tls_align)
409 static_tls_align = STACK_ALIGN;
410 __static_tls_align_m1 = static_tls_align - 1;
411
412 __static_tls_size = roundup (__static_tls_size, static_tls_align);
413
414 /* Determine the default allowed stack size. This is the size used
415 in case the user does not specify one. */
416 struct rlimit limit;
417 if (__getrlimit (RLIMIT_STACK, &limit) != 0
418 || limit.rlim_cur == RLIM_INFINITY)
419 /* The system limit is not usable. Use an architecture-specific
420 default. */
421 limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
422 else if (limit.rlim_cur < PTHREAD_STACK_MIN)
423 /* The system limit is unusably small.
424 Use the minimal size acceptable. */
425 limit.rlim_cur = PTHREAD_STACK_MIN;
426
427 /* Make sure it meets the minimum size that allocate_stack
428 (allocatestack.c) will demand, which depends on the page size. */
429 const uintptr_t pagesz = GLRO(dl_pagesize);
430 const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
431 if (limit.rlim_cur < minstack)
432 limit.rlim_cur = minstack;
433
434 /* Round the resource limit up to page size. */
435 limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz);
436 lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
437 __default_pthread_attr.stacksize = limit.rlim_cur;
438 __default_pthread_attr.guardsize = GLRO (dl_pagesize);
439 lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
440
441#ifdef SHARED
442 /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock,
443 keep the lock count from the ld.so implementation. */
444 GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock;
445 GL(dl_rtld_unlock_recursive) = (void *) __pthread_mutex_unlock;
446 unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count;
447 GL(dl_load_lock).mutex.__data.__count = 0;
448 while (rtld_lock_count-- > 0)
449 __pthread_mutex_lock (&GL(dl_load_lock).mutex);
450
451 GL(dl_make_stack_executable_hook) = &__make_stacks_executable;
452#endif
453
454 GL(dl_init_static_tls) = &__pthread_init_static_tls;
455
456 GL(dl_wait_lookup_done) = &__wait_lookup_done;
457
458 /* Register the fork generation counter with the libc. */
459#ifndef TLS_MULTIPLE_THREADS_IN_TCB
460 __libc_multiple_threads_ptr =
461#endif
462 __libc_pthread_init (&__fork_generation, __reclaim_stacks,
463 ptr_pthread_functions);
464
465 /* Determine whether the machine is SMP or not. */
466 __is_smp = is_smp_system ();
467}
468strong_alias (__pthread_initialize_minimal_internal,
469 __pthread_initialize_minimal)
470
471
472size_t
473__pthread_get_minstack (const pthread_attr_t *attr)
474{
475 return GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN;
476}
477