1/* Copyright (C) 2002-2017 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#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_self = __pthread_self,
126 .ptr___pthread_setcancelstate = __pthread_setcancelstate,
127 .ptr_pthread_setcanceltype = __pthread_setcanceltype,
128 .ptr___pthread_cleanup_upto = __pthread_cleanup_upto,
129 .ptr___pthread_once = __pthread_once,
130 .ptr___pthread_rwlock_rdlock = __pthread_rwlock_rdlock,
131 .ptr___pthread_rwlock_wrlock = __pthread_rwlock_wrlock,
132 .ptr___pthread_rwlock_unlock = __pthread_rwlock_unlock,
133 .ptr___pthread_key_create = __pthread_key_create,
134 .ptr___pthread_getspecific = __pthread_getspecific,
135 .ptr___pthread_setspecific = __pthread_setspecific,
136 .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer,
137 .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore,
138 .ptr_nthreads = &__nptl_nthreads,
139 .ptr___pthread_unwind = &__pthread_unwind,
140 .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd,
141# ifdef SIGSETXID
142 .ptr__nptl_setxid = __nptl_setxid,
143# endif
144 /* For now only the stack cache needs to be freed. */
145 .ptr_freeres = nptl_freeres,
146 .ptr_set_robust = __nptl_set_robust
147 };
148# define ptr_pthread_functions &pthread_functions
149#else
150# define ptr_pthread_functions NULL
151#endif
152
153
154#ifdef SHARED
155/* This function is called indirectly from the freeres code in libc. */
156static void
157__libc_freeres_fn_section
158nptl_freeres (void)
159{
160 __unwind_freeres ();
161 __free_stacks (0);
162}
163
164
165static
166#endif
167void
168__nptl_set_robust (struct pthread *self)
169{
170#ifdef __NR_set_robust_list
171 INTERNAL_SYSCALL_DECL (err);
172 INTERNAL_SYSCALL (set_robust_list, err, 2, &self->robust_head,
173 sizeof (struct robust_list_head));
174#endif
175}
176
177
178#ifdef SIGCANCEL
179/* For asynchronous cancellation we use a signal. This is the handler. */
180static void
181sigcancel_handler (int sig, siginfo_t *si, void *ctx)
182{
183 /* Safety check. It would be possible to call this function for
184 other signals and send a signal from another process. This is not
185 correct and might even be a security problem. Try to catch as
186 many incorrect invocations as possible. */
187 if (sig != SIGCANCEL
188 || si->si_pid != __getpid()
189 || si->si_code != SI_TKILL)
190 return;
191
192 struct pthread *self = THREAD_SELF;
193
194 int oldval = THREAD_GETMEM (self, cancelhandling);
195 while (1)
196 {
197 /* We are canceled now. When canceled by another thread this flag
198 is already set but if the signal is directly send (internally or
199 from another process) is has to be done here. */
200 int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
201
202 if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
203 /* Already canceled or exiting. */
204 break;
205
206 int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
207 oldval);
208 if (curval == oldval)
209 {
210 /* Set the return value. */
211 THREAD_SETMEM (self, result, PTHREAD_CANCELED);
212
213 /* Make sure asynchronous cancellation is still enabled. */
214 if ((newval & CANCELTYPE_BITMASK) != 0)
215 /* Run the registered destructors and terminate the thread. */
216 __do_cancel ();
217
218 break;
219 }
220
221 oldval = curval;
222 }
223}
224#endif
225
226
227#ifdef SIGSETXID
228struct xid_command *__xidcmd attribute_hidden;
229
230/* We use the SIGSETXID signal in the setuid, setgid, etc. implementations to
231 tell each thread to call the respective setxid syscall on itself. This is
232 the handler. */
233static void
234sighandler_setxid (int sig, siginfo_t *si, void *ctx)
235{
236 int result;
237
238 /* Safety check. It would be possible to call this function for
239 other signals and send a signal from another process. This is not
240 correct and might even be a security problem. Try to catch as
241 many incorrect invocations as possible. */
242 if (sig != SIGSETXID
243 || si->si_pid != __getpid ()
244 || si->si_code != SI_TKILL)
245 return;
246
247 INTERNAL_SYSCALL_DECL (err);
248 result = INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
249 __xidcmd->id[1], __xidcmd->id[2]);
250 int error = 0;
251 if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
252 error = INTERNAL_SYSCALL_ERRNO (result, err);
253 __nptl_setxid_error (__xidcmd, error);
254
255 /* Reset the SETXID flag. */
256 struct pthread *self = THREAD_SELF;
257 int flags, newval;
258 do
259 {
260 flags = THREAD_GETMEM (self, cancelhandling);
261 newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
262 flags & ~SETXID_BITMASK, flags);
263 }
264 while (flags != newval);
265
266 /* And release the futex. */
267 self->setxid_futex = 1;
268 futex_wake (&self->setxid_futex, 1, FUTEX_PRIVATE);
269
270 if (atomic_decrement_val (&__xidcmd->cntr) == 0)
271 futex_wake ((unsigned int *) &__xidcmd->cntr, 1, FUTEX_PRIVATE);
272}
273#endif
274
275
276/* When using __thread for this, we do it in libc so as not
277 to give libpthread its own TLS segment just for this. */
278extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
279
280
281/* This can be set by the debugger before initialization is complete. */
282static bool __nptl_initial_report_events __attribute_used__;
283
284void
285__pthread_initialize_minimal_internal (void)
286{
287 /* Minimal initialization of the thread descriptor. */
288 struct pthread *pd = THREAD_SELF;
289 __pthread_initialize_pids (pd);
290 THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
291 THREAD_SETMEM (pd, user_stack, true);
292 if (LLL_LOCK_INITIALIZER != 0)
293 THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
294#if HP_TIMING_AVAIL
295 THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
296#endif
297
298 /* Initialize the robust mutex data. */
299 {
300#ifdef __PTHREAD_MUTEX_HAVE_PREV
301 pd->robust_prev = &pd->robust_head;
302#endif
303 pd->robust_head.list = &pd->robust_head;
304#ifdef __NR_set_robust_list
305 pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
306 - offsetof (pthread_mutex_t,
307 __data.__list.__next));
308 INTERNAL_SYSCALL_DECL (err);
309 int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
310 sizeof (struct robust_list_head));
311 if (INTERNAL_SYSCALL_ERROR_P (res, err))
312#endif
313 set_robust_list_not_avail ();
314 }
315
316#ifdef __NR_futex
317# ifndef __ASSUME_PRIVATE_FUTEX
318 /* Private futexes are always used (at least internally) so that
319 doing the test once this early is beneficial. */
320 {
321 int word = 0;
322 INTERNAL_SYSCALL_DECL (err);
323 word = INTERNAL_SYSCALL (futex, err, 3, &word,
324 FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1);
325 if (!INTERNAL_SYSCALL_ERROR_P (word, err))
326 THREAD_SETMEM (pd, header.private_futex, FUTEX_PRIVATE_FLAG);
327 }
328
329 /* Private futexes have been introduced earlier than the
330 FUTEX_CLOCK_REALTIME flag. We don't have to run the test if we
331 know the former are not supported. This also means we know the
332 kernel will return ENOSYS for unknown operations. */
333 if (THREAD_GETMEM (pd, header.private_futex) != 0)
334# endif
335# ifndef __ASSUME_FUTEX_CLOCK_REALTIME
336 {
337 int word = 0;
338 /* NB: the syscall actually takes six parameters. The last is the
339 bit mask. But since we will not actually wait at all the value
340 is irrelevant. Given that passing six parameters is difficult
341 on some architectures we just pass whatever random value the
342 calling convention calls for to the kernel. It causes no harm. */
343 INTERNAL_SYSCALL_DECL (err);
344 word = INTERNAL_SYSCALL (futex, err, 5, &word,
345 FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME
346 | FUTEX_PRIVATE_FLAG, 1, NULL, 0);
347 assert (INTERNAL_SYSCALL_ERROR_P (word, err));
348 if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS)
349 __set_futex_clock_realtime ();
350 }
351# endif
352#endif
353
354 /* Set initial thread's stack block from 0 up to __libc_stack_end.
355 It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
356 purposes this is good enough. */
357 THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
358
359 /* Initialize the list of all running threads with the main thread. */
360 INIT_LIST_HEAD (&__stack_user);
361 list_add (&pd->list, &__stack_user);
362
363 /* Before initializing __stack_user, the debugger could not find us and
364 had to set __nptl_initial_report_events. Propagate its setting. */
365 THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
366
367#if defined SIGCANCEL || defined SIGSETXID
368 struct sigaction sa;
369 __sigemptyset (&sa.sa_mask);
370
371# ifdef SIGCANCEL
372 /* Install the cancellation signal handler. If for some reason we
373 cannot install the handler we do not abort. Maybe we should, but
374 it is only asynchronous cancellation which is affected. */
375 sa.sa_sigaction = sigcancel_handler;
376 sa.sa_flags = SA_SIGINFO;
377 (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
378# endif
379
380# ifdef SIGSETXID
381 /* Install the handle to change the threads' uid/gid. */
382 sa.sa_sigaction = sighandler_setxid;
383 sa.sa_flags = SA_SIGINFO | SA_RESTART;
384 (void) __libc_sigaction (SIGSETXID, &sa, NULL);
385# endif
386
387 /* The parent process might have left the signals blocked. Just in
388 case, unblock it. We reuse the signal mask in the sigaction
389 structure. It is already cleared. */
390# ifdef SIGCANCEL
391 __sigaddset (&sa.sa_mask, SIGCANCEL);
392# endif
393# ifdef SIGSETXID
394 __sigaddset (&sa.sa_mask, SIGSETXID);
395# endif
396 {
397 INTERNAL_SYSCALL_DECL (err);
398 (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
399 NULL, _NSIG / 8);
400 }
401#endif
402
403 /* Get the size of the static and alignment requirements for the TLS
404 block. */
405 size_t static_tls_align;
406 _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
407
408 /* Make sure the size takes all the alignments into account. */
409 if (STACK_ALIGN > static_tls_align)
410 static_tls_align = STACK_ALIGN;
411 __static_tls_align_m1 = static_tls_align - 1;
412
413 __static_tls_size = roundup (__static_tls_size, static_tls_align);
414
415 /* Determine the default allowed stack size. This is the size used
416 in case the user does not specify one. */
417 struct rlimit limit;
418 if (__getrlimit (RLIMIT_STACK, &limit) != 0
419 || limit.rlim_cur == RLIM_INFINITY)
420 /* The system limit is not usable. Use an architecture-specific
421 default. */
422 limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
423 else if (limit.rlim_cur < PTHREAD_STACK_MIN)
424 /* The system limit is unusably small.
425 Use the minimal size acceptable. */
426 limit.rlim_cur = PTHREAD_STACK_MIN;
427
428 /* Make sure it meets the minimum size that allocate_stack
429 (allocatestack.c) will demand, which depends on the page size. */
430 const uintptr_t pagesz = GLRO(dl_pagesize);
431 const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
432 if (limit.rlim_cur < minstack)
433 limit.rlim_cur = minstack;
434
435 /* Round the resource limit up to page size. */
436 limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz);
437 lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
438 __default_pthread_attr.stacksize = limit.rlim_cur;
439 __default_pthread_attr.guardsize = GLRO (dl_pagesize);
440 lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
441
442#ifdef SHARED
443 /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock,
444 keep the lock count from the ld.so implementation. */
445 GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock;
446 GL(dl_rtld_unlock_recursive) = (void *) __pthread_mutex_unlock;
447 unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count;
448 GL(dl_load_lock).mutex.__data.__count = 0;
449 while (rtld_lock_count-- > 0)
450 __pthread_mutex_lock (&GL(dl_load_lock).mutex);
451
452 GL(dl_make_stack_executable_hook) = &__make_stacks_executable;
453#endif
454
455 GL(dl_init_static_tls) = &__pthread_init_static_tls;
456
457 GL(dl_wait_lookup_done) = &__wait_lookup_done;
458
459 /* Register the fork generation counter with the libc. */
460#ifndef TLS_MULTIPLE_THREADS_IN_TCB
461 __libc_multiple_threads_ptr =
462#endif
463 __libc_pthread_init (&__fork_generation, __reclaim_stacks,
464 ptr_pthread_functions);
465
466 /* Determine whether the machine is SMP or not. */
467 __is_smp = is_smp_system ();
468}
469strong_alias (__pthread_initialize_minimal_internal,
470 __pthread_initialize_minimal)
471
472
473size_t
474__pthread_get_minstack (const pthread_attr_t *attr)
475{
476 struct pthread_attr *iattr = (struct pthread_attr *) attr;
477
478 return (GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN
479 + iattr->guardsize);
480}
481