1/* Copyright (C) 2002-2016 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-internal.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#ifndef SHARED
74extern void __libc_setup_tls (size_t tcbsize, size_t tcbalign);
75#endif
76
77#ifdef SHARED
78static
79#else
80extern
81#endif
82void __nptl_set_robust (struct pthread *);
83
84#ifdef SHARED
85static void nptl_freeres (void);
86
87
88static const struct pthread_functions pthread_functions =
89 {
90 .ptr_pthread_attr_destroy = __pthread_attr_destroy,
91# if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
92 .ptr___pthread_attr_init_2_0 = __pthread_attr_init_2_0,
93# endif
94 .ptr___pthread_attr_init_2_1 = __pthread_attr_init_2_1,
95 .ptr_pthread_attr_getdetachstate = __pthread_attr_getdetachstate,
96 .ptr_pthread_attr_setdetachstate = __pthread_attr_setdetachstate,
97 .ptr_pthread_attr_getinheritsched = __pthread_attr_getinheritsched,
98 .ptr_pthread_attr_setinheritsched = __pthread_attr_setinheritsched,
99 .ptr_pthread_attr_getschedparam = __pthread_attr_getschedparam,
100 .ptr_pthread_attr_setschedparam = __pthread_attr_setschedparam,
101 .ptr_pthread_attr_getschedpolicy = __pthread_attr_getschedpolicy,
102 .ptr_pthread_attr_setschedpolicy = __pthread_attr_setschedpolicy,
103 .ptr_pthread_attr_getscope = __pthread_attr_getscope,
104 .ptr_pthread_attr_setscope = __pthread_attr_setscope,
105 .ptr_pthread_condattr_destroy = __pthread_condattr_destroy,
106 .ptr_pthread_condattr_init = __pthread_condattr_init,
107 .ptr___pthread_cond_broadcast = __pthread_cond_broadcast,
108 .ptr___pthread_cond_destroy = __pthread_cond_destroy,
109 .ptr___pthread_cond_init = __pthread_cond_init,
110 .ptr___pthread_cond_signal = __pthread_cond_signal,
111 .ptr___pthread_cond_wait = __pthread_cond_wait,
112 .ptr___pthread_cond_timedwait = __pthread_cond_timedwait,
113# if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_3_2)
114 .ptr___pthread_cond_broadcast_2_0 = __pthread_cond_broadcast_2_0,
115 .ptr___pthread_cond_destroy_2_0 = __pthread_cond_destroy_2_0,
116 .ptr___pthread_cond_init_2_0 = __pthread_cond_init_2_0,
117 .ptr___pthread_cond_signal_2_0 = __pthread_cond_signal_2_0,
118 .ptr___pthread_cond_wait_2_0 = __pthread_cond_wait_2_0,
119 .ptr___pthread_cond_timedwait_2_0 = __pthread_cond_timedwait_2_0,
120# endif
121 .ptr_pthread_equal = __pthread_equal,
122 .ptr___pthread_exit = __pthread_exit,
123 .ptr_pthread_getschedparam = __pthread_getschedparam,
124 .ptr_pthread_setschedparam = __pthread_setschedparam,
125 .ptr_pthread_mutex_destroy = __pthread_mutex_destroy,
126 .ptr_pthread_mutex_init = __pthread_mutex_init,
127 .ptr_pthread_mutex_lock = __pthread_mutex_lock,
128 .ptr_pthread_mutex_unlock = __pthread_mutex_unlock,
129 .ptr_pthread_self = __pthread_self,
130 .ptr___pthread_setcancelstate = __pthread_setcancelstate,
131 .ptr_pthread_setcanceltype = __pthread_setcanceltype,
132 .ptr___pthread_cleanup_upto = __pthread_cleanup_upto,
133 .ptr___pthread_once = __pthread_once,
134 .ptr___pthread_rwlock_rdlock = __pthread_rwlock_rdlock,
135 .ptr___pthread_rwlock_wrlock = __pthread_rwlock_wrlock,
136 .ptr___pthread_rwlock_unlock = __pthread_rwlock_unlock,
137 .ptr___pthread_key_create = __pthread_key_create,
138 .ptr___pthread_getspecific = __pthread_getspecific,
139 .ptr___pthread_setspecific = __pthread_setspecific,
140 .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer,
141 .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore,
142 .ptr_nthreads = &__nptl_nthreads,
143 .ptr___pthread_unwind = &__pthread_unwind,
144 .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd,
145# ifdef SIGSETXID
146 .ptr__nptl_setxid = __nptl_setxid,
147# endif
148 /* For now only the stack cache needs to be freed. */
149 .ptr_freeres = nptl_freeres,
150 .ptr_set_robust = __nptl_set_robust
151 };
152# define ptr_pthread_functions &pthread_functions
153#else
154# define ptr_pthread_functions NULL
155#endif
156
157
158#ifdef SHARED
159/* This function is called indirectly from the freeres code in libc. */
160static void
161__libc_freeres_fn_section
162nptl_freeres (void)
163{
164 __unwind_freeres ();
165 __free_stacks (0);
166}
167
168
169static
170#endif
171void
172__nptl_set_robust (struct pthread *self)
173{
174#ifdef __NR_set_robust_list
175 INTERNAL_SYSCALL_DECL (err);
176 INTERNAL_SYSCALL (set_robust_list, err, 2, &self->robust_head,
177 sizeof (struct robust_list_head));
178#endif
179}
180
181
182#ifdef SIGCANCEL
183/* For asynchronous cancellation we use a signal. This is the handler. */
184static void
185sigcancel_handler (int sig, siginfo_t *si, void *ctx)
186{
187 /* Determine the process ID. It might be negative if the thread is
188 in the middle of a fork() call. */
189 pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
190 if (__glibc_unlikely (pid < 0))
191 pid = -pid;
192
193 /* Safety check. It would be possible to call this function for
194 other signals and send a signal from another process. This is not
195 correct and might even be a security problem. Try to catch as
196 many incorrect invocations as possible. */
197 if (sig != SIGCANCEL
198 || si->si_pid != pid
199 || si->si_code != SI_TKILL)
200 return;
201
202 struct pthread *self = THREAD_SELF;
203
204 int oldval = THREAD_GETMEM (self, cancelhandling);
205 while (1)
206 {
207 /* We are canceled now. When canceled by another thread this flag
208 is already set but if the signal is directly send (internally or
209 from another process) is has to be done here. */
210 int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
211
212 if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
213 /* Already canceled or exiting. */
214 break;
215
216 int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
217 oldval);
218 if (curval == oldval)
219 {
220 /* Set the return value. */
221 THREAD_SETMEM (self, result, PTHREAD_CANCELED);
222
223 /* Make sure asynchronous cancellation is still enabled. */
224 if ((newval & CANCELTYPE_BITMASK) != 0)
225 /* Run the registered destructors and terminate the thread. */
226 __do_cancel ();
227
228 break;
229 }
230
231 oldval = curval;
232 }
233}
234#endif
235
236
237#ifdef SIGSETXID
238struct xid_command *__xidcmd attribute_hidden;
239
240/* We use the SIGSETXID signal in the setuid, setgid, etc. implementations to
241 tell each thread to call the respective setxid syscall on itself. This is
242 the handler. */
243static void
244sighandler_setxid (int sig, siginfo_t *si, void *ctx)
245{
246 /* Determine the process ID. It might be negative if the thread is
247 in the middle of a fork() call. */
248 pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
249 int result;
250 if (__glibc_unlikely (pid < 0))
251 pid = -pid;
252
253 /* Safety check. It would be possible to call this function for
254 other signals and send a signal from another process. This is not
255 correct and might even be a security problem. Try to catch as
256 many incorrect invocations as possible. */
257 if (sig != SIGSETXID
258 || si->si_pid != pid
259 || si->si_code != SI_TKILL)
260 return;
261
262 INTERNAL_SYSCALL_DECL (err);
263 result = INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
264 __xidcmd->id[1], __xidcmd->id[2]);
265 int error = 0;
266 if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
267 error = INTERNAL_SYSCALL_ERRNO (result, err);
268 __nptl_setxid_error (__xidcmd, error);
269
270 /* Reset the SETXID flag. */
271 struct pthread *self = THREAD_SELF;
272 int flags, newval;
273 do
274 {
275 flags = THREAD_GETMEM (self, cancelhandling);
276 newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
277 flags & ~SETXID_BITMASK, flags);
278 }
279 while (flags != newval);
280
281 /* And release the futex. */
282 self->setxid_futex = 1;
283 futex_wake (&self->setxid_futex, 1, FUTEX_PRIVATE);
284
285 if (atomic_decrement_val (&__xidcmd->cntr) == 0)
286 futex_wake ((unsigned int *) &__xidcmd->cntr, 1, FUTEX_PRIVATE);
287}
288#endif
289
290
291/* When using __thread for this, we do it in libc so as not
292 to give libpthread its own TLS segment just for this. */
293extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
294
295
296/* This can be set by the debugger before initialization is complete. */
297static bool __nptl_initial_report_events __attribute_used__;
298
299void
300__pthread_initialize_minimal_internal (void)
301{
302#ifndef SHARED
303 /* Unlike in the dynamically linked case the dynamic linker has not
304 taken care of initializing the TLS data structures. */
305 __libc_setup_tls (TLS_TCB_SIZE, TLS_TCB_ALIGN);
306
307 /* We must prevent gcc from being clever and move any of the
308 following code ahead of the __libc_setup_tls call. This function
309 will initialize the thread register which is subsequently
310 used. */
311 __asm __volatile ("");
312#endif
313
314 /* Minimal initialization of the thread descriptor. */
315 struct pthread *pd = THREAD_SELF;
316 __pthread_initialize_pids (pd);
317 THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
318 THREAD_SETMEM (pd, user_stack, true);
319 if (LLL_LOCK_INITIALIZER != 0)
320 THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
321#if HP_TIMING_AVAIL
322 THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
323#endif
324
325 /* Initialize the robust mutex data. */
326 {
327#ifdef __PTHREAD_MUTEX_HAVE_PREV
328 pd->robust_prev = &pd->robust_head;
329#endif
330 pd->robust_head.list = &pd->robust_head;
331#ifdef __NR_set_robust_list
332 pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
333 - offsetof (pthread_mutex_t,
334 __data.__list.__next));
335 INTERNAL_SYSCALL_DECL (err);
336 int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
337 sizeof (struct robust_list_head));
338 if (INTERNAL_SYSCALL_ERROR_P (res, err))
339#endif
340 set_robust_list_not_avail ();
341 }
342
343#ifdef __NR_futex
344# ifndef __ASSUME_PRIVATE_FUTEX
345 /* Private futexes are always used (at least internally) so that
346 doing the test once this early is beneficial. */
347 {
348 int word = 0;
349 INTERNAL_SYSCALL_DECL (err);
350 word = INTERNAL_SYSCALL (futex, err, 3, &word,
351 FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1);
352 if (!INTERNAL_SYSCALL_ERROR_P (word, err))
353 THREAD_SETMEM (pd, header.private_futex, FUTEX_PRIVATE_FLAG);
354 }
355
356 /* Private futexes have been introduced earlier than the
357 FUTEX_CLOCK_REALTIME flag. We don't have to run the test if we
358 know the former are not supported. This also means we know the
359 kernel will return ENOSYS for unknown operations. */
360 if (THREAD_GETMEM (pd, header.private_futex) != 0)
361# endif
362# ifndef __ASSUME_FUTEX_CLOCK_REALTIME
363 {
364 int word = 0;
365 /* NB: the syscall actually takes six parameters. The last is the
366 bit mask. But since we will not actually wait at all the value
367 is irrelevant. Given that passing six parameters is difficult
368 on some architectures we just pass whatever random value the
369 calling convention calls for to the kernel. It causes no harm. */
370 INTERNAL_SYSCALL_DECL (err);
371 word = INTERNAL_SYSCALL (futex, err, 5, &word,
372 FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME
373 | FUTEX_PRIVATE_FLAG, 1, NULL, 0);
374 assert (INTERNAL_SYSCALL_ERROR_P (word, err));
375 if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS)
376 __set_futex_clock_realtime ();
377 }
378# endif
379#endif
380
381 /* Set initial thread's stack block from 0 up to __libc_stack_end.
382 It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
383 purposes this is good enough. */
384 THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
385
386 /* Initialize the list of all running threads with the main thread. */
387 INIT_LIST_HEAD (&__stack_user);
388 list_add (&pd->list, &__stack_user);
389
390 /* Before initializing __stack_user, the debugger could not find us and
391 had to set __nptl_initial_report_events. Propagate its setting. */
392 THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
393
394#if defined SIGCANCEL || defined SIGSETXID
395 struct sigaction sa;
396 __sigemptyset (&sa.sa_mask);
397
398# ifdef SIGCANCEL
399 /* Install the cancellation signal handler. If for some reason we
400 cannot install the handler we do not abort. Maybe we should, but
401 it is only asynchronous cancellation which is affected. */
402 sa.sa_sigaction = sigcancel_handler;
403 sa.sa_flags = SA_SIGINFO;
404 (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
405# endif
406
407# ifdef SIGSETXID
408 /* Install the handle to change the threads' uid/gid. */
409 sa.sa_sigaction = sighandler_setxid;
410 sa.sa_flags = SA_SIGINFO | SA_RESTART;
411 (void) __libc_sigaction (SIGSETXID, &sa, NULL);
412# endif
413
414 /* The parent process might have left the signals blocked. Just in
415 case, unblock it. We reuse the signal mask in the sigaction
416 structure. It is already cleared. */
417# ifdef SIGCANCEL
418 __sigaddset (&sa.sa_mask, SIGCANCEL);
419# endif
420# ifdef SIGSETXID
421 __sigaddset (&sa.sa_mask, SIGSETXID);
422# endif
423 {
424 INTERNAL_SYSCALL_DECL (err);
425 (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
426 NULL, _NSIG / 8);
427 }
428#endif
429
430 /* Get the size of the static and alignment requirements for the TLS
431 block. */
432 size_t static_tls_align;
433 _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
434
435 /* Make sure the size takes all the alignments into account. */
436 if (STACK_ALIGN > static_tls_align)
437 static_tls_align = STACK_ALIGN;
438 __static_tls_align_m1 = static_tls_align - 1;
439
440 __static_tls_size = roundup (__static_tls_size, static_tls_align);
441
442 /* Determine the default allowed stack size. This is the size used
443 in case the user does not specify one. */
444 struct rlimit limit;
445 if (__getrlimit (RLIMIT_STACK, &limit) != 0
446 || limit.rlim_cur == RLIM_INFINITY)
447 /* The system limit is not usable. Use an architecture-specific
448 default. */
449 limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
450 else if (limit.rlim_cur < PTHREAD_STACK_MIN)
451 /* The system limit is unusably small.
452 Use the minimal size acceptable. */
453 limit.rlim_cur = PTHREAD_STACK_MIN;
454
455 /* Make sure it meets the minimum size that allocate_stack
456 (allocatestack.c) will demand, which depends on the page size. */
457 const uintptr_t pagesz = GLRO(dl_pagesize);
458 const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
459 if (limit.rlim_cur < minstack)
460 limit.rlim_cur = minstack;
461
462 /* Round the resource limit up to page size. */
463 limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz);
464 lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
465 __default_pthread_attr.stacksize = limit.rlim_cur;
466 __default_pthread_attr.guardsize = GLRO (dl_pagesize);
467 lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
468
469#ifdef SHARED
470 /* Transfer the old value from the dynamic linker's internal location. */
471 *__libc_dl_error_tsd () = *(*GL(dl_error_catch_tsd)) ();
472 GL(dl_error_catch_tsd) = &__libc_dl_error_tsd;
473
474 /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock,
475 keep the lock count from the ld.so implementation. */
476 GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock;
477 GL(dl_rtld_unlock_recursive) = (void *) __pthread_mutex_unlock;
478 unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count;
479 GL(dl_load_lock).mutex.__data.__count = 0;
480 while (rtld_lock_count-- > 0)
481 __pthread_mutex_lock (&GL(dl_load_lock).mutex);
482
483 GL(dl_make_stack_executable_hook) = &__make_stacks_executable;
484#endif
485
486 GL(dl_init_static_tls) = &__pthread_init_static_tls;
487
488 GL(dl_wait_lookup_done) = &__wait_lookup_done;
489
490 /* Register the fork generation counter with the libc. */
491#ifndef TLS_MULTIPLE_THREADS_IN_TCB
492 __libc_multiple_threads_ptr =
493#endif
494 __libc_pthread_init (&__fork_generation, __reclaim_stacks,
495 ptr_pthread_functions);
496
497 /* Determine whether the machine is SMP or not. */
498 __is_smp = is_smp_system ();
499}
500strong_alias (__pthread_initialize_minimal_internal,
501 __pthread_initialize_minimal)
502
503
504size_t
505__pthread_get_minstack (const pthread_attr_t *attr)
506{
507 struct pthread_attr *iattr = (struct pthread_attr *) attr;
508
509 return (GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN
510 + iattr->guardsize);
511}
512