nptl/nptl-init.c

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