nptl/nptl-init.c

   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-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 void nptl_freeres (void);
  82
  83
  84 static 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.  */
 156 static void
 157 __libc_freeres_fn_section
 158 nptl_freeres (void)
 159 {
 160   __unwind_freeres ();
 161   __free_stacks (0);
 162 }
 163
 164
 165 static
 166 #endif
 167 void
 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.  */
 180 static void
 181 sigcancel_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
 228 struct 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.  */
 233 static void
 234 sighandler_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.  */
 278 extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
 279
 280
 281 /* This can be set by the debugger before initialization is complete.  */
 282 static bool __nptl_initial_report_events __attribute_used__;
 283
 284 void
 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 }
 469 strong_alias (__pthread_initialize_minimal_internal,
 470               __pthread_initialize_minimal)
 471
 472
 473 size_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 }