nptl/nptl-init.c

   1 /* Copyright (C) 2002-2015 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 <kernel-features.h>
  38 #include <libc-internal.h>
  39
  40 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
  41 /* Pointer to the corresponding variable in libc.  */
  42 int *__libc_multiple_threads_ptr attribute_hidden;
  43 #endif
  44
  45 /* Size and alignment of static TLS block.  */
  46 size_t __static_tls_size;
  47 size_t __static_tls_align_m1;
  48
  49 #ifndef __ASSUME_SET_ROBUST_LIST
  50 /* Negative if we do not have the system call and we can use it.  */
  51 int __set_robust_list_avail;
  52 # define set_robust_list_not_avail() \
  53   __set_robust_list_avail = -1
  54 #else
  55 # define set_robust_list_not_avail() do { } while (0)
  56 #endif
  57
  58 #ifndef __ASSUME_FUTEX_CLOCK_REALTIME
  59 /* Nonzero if we do not have FUTEX_CLOCK_REALTIME.  */
  60 int __have_futex_clock_realtime;
  61 # define __set_futex_clock_realtime() \
  62   __have_futex_clock_realtime = 1
  63 #else
  64 #define __set_futex_clock_realtime() do { } while (0)
  65 #endif
  66
  67 /* Version of the library, used in libthread_db to detect mismatches.  */
  68 static const char nptl_version[] __attribute_used__ = VERSION;
  69
  70
  71 #ifndef SHARED
  72 extern void __libc_setup_tls (size_t tcbsize, size_t tcbalign);
  73 #endif
  74
  75 #ifdef SHARED
  76 static
  77 #else
  78 extern
  79 #endif
  80 void __nptl_set_robust (struct pthread *);
  81
  82 #ifdef SHARED
  83 static void nptl_freeres (void);
  84
  85
  86 static const struct pthread_functions pthread_functions =
  87   {
  88     .ptr_pthread_attr_destroy = __pthread_attr_destroy,
  89 # if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
  90     .ptr___pthread_attr_init_2_0 = __pthread_attr_init_2_0,
  91 # endif
  92     .ptr___pthread_attr_init_2_1 = __pthread_attr_init_2_1,
  93     .ptr_pthread_attr_getdetachstate = __pthread_attr_getdetachstate,
  94     .ptr_pthread_attr_setdetachstate = __pthread_attr_setdetachstate,
  95     .ptr_pthread_attr_getinheritsched = __pthread_attr_getinheritsched,
  96     .ptr_pthread_attr_setinheritsched = __pthread_attr_setinheritsched,
  97     .ptr_pthread_attr_getschedparam = __pthread_attr_getschedparam,
  98     .ptr_pthread_attr_setschedparam = __pthread_attr_setschedparam,
  99     .ptr_pthread_attr_getschedpolicy = __pthread_attr_getschedpolicy,
 100     .ptr_pthread_attr_setschedpolicy = __pthread_attr_setschedpolicy,
 101     .ptr_pthread_attr_getscope = __pthread_attr_getscope,
 102     .ptr_pthread_attr_setscope = __pthread_attr_setscope,
 103     .ptr_pthread_condattr_destroy = __pthread_condattr_destroy,
 104     .ptr_pthread_condattr_init = __pthread_condattr_init,
 105     .ptr___pthread_cond_broadcast = __pthread_cond_broadcast,
 106     .ptr___pthread_cond_destroy = __pthread_cond_destroy,
 107     .ptr___pthread_cond_init = __pthread_cond_init,
 108     .ptr___pthread_cond_signal = __pthread_cond_signal,
 109     .ptr___pthread_cond_wait = __pthread_cond_wait,
 110     .ptr___pthread_cond_timedwait = __pthread_cond_timedwait,
 111 # if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_3_2)
 112     .ptr___pthread_cond_broadcast_2_0 = __pthread_cond_broadcast_2_0,
 113     .ptr___pthread_cond_destroy_2_0 = __pthread_cond_destroy_2_0,
 114     .ptr___pthread_cond_init_2_0 = __pthread_cond_init_2_0,
 115     .ptr___pthread_cond_signal_2_0 = __pthread_cond_signal_2_0,
 116     .ptr___pthread_cond_wait_2_0 = __pthread_cond_wait_2_0,
 117     .ptr___pthread_cond_timedwait_2_0 = __pthread_cond_timedwait_2_0,
 118 # endif
 119     .ptr_pthread_equal = __pthread_equal,
 120     .ptr___pthread_exit = __pthread_exit,
 121     .ptr_pthread_getschedparam = __pthread_getschedparam,
 122     .ptr_pthread_setschedparam = __pthread_setschedparam,
 123     .ptr_pthread_mutex_destroy = __pthread_mutex_destroy,
 124     .ptr_pthread_mutex_init = __pthread_mutex_init,
 125     .ptr_pthread_mutex_lock = __pthread_mutex_lock,
 126     .ptr_pthread_mutex_unlock = __pthread_mutex_unlock,
 127     .ptr_pthread_self = __pthread_self,
 128     .ptr_pthread_setcancelstate = __pthread_setcancelstate,
 129     .ptr_pthread_setcanceltype = __pthread_setcanceltype,
 130     .ptr___pthread_cleanup_upto = __pthread_cleanup_upto,
 131     .ptr___pthread_once = __pthread_once,
 132     .ptr___pthread_rwlock_rdlock = __pthread_rwlock_rdlock,
 133     .ptr___pthread_rwlock_wrlock = __pthread_rwlock_wrlock,
 134     .ptr___pthread_rwlock_unlock = __pthread_rwlock_unlock,
 135     .ptr___pthread_key_create = __pthread_key_create,
 136     .ptr___pthread_getspecific = __pthread_getspecific,
 137     .ptr___pthread_setspecific = __pthread_setspecific,
 138     .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer,
 139     .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore,
 140     .ptr_nthreads = &__nptl_nthreads,
 141     .ptr___pthread_unwind = &__pthread_unwind,
 142     .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd,
 143     .ptr__nptl_setxid = __nptl_setxid,
 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   /* Determine the process ID.  It might be negative if the thread is
 184      in the middle of a fork() call.  */
 185   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
 186   if (__glibc_unlikely (pid < 0))
 187     pid = -pid;
 188
 189   /* Safety check.  It would be possible to call this function for
 190      other signals and send a signal from another process.  This is not
 191      correct and might even be a security problem.  Try to catch as
 192      many incorrect invocations as possible.  */
 193   if (sig != SIGCANCEL
 194       || si->si_pid != pid
 195       || si->si_code != SI_TKILL)
 196     return;
 197
 198   struct pthread *self = THREAD_SELF;
 199
 200   int oldval = THREAD_GETMEM (self, cancelhandling);
 201   while (1)
 202     {
 203       /* We are canceled now.  When canceled by another thread this flag
 204          is already set but if the signal is directly send (internally or
 205          from another process) is has to be done here.  */
 206       int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
 207
 208       if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
 209         /* Already canceled or exiting.  */
 210         break;
 211
 212       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
 213                                               oldval);
 214       if (curval == oldval)
 215         {
 216           /* Set the return value.  */
 217           THREAD_SETMEM (self, result, PTHREAD_CANCELED);
 218
 219           /* Make sure asynchronous cancellation is still enabled.  */
 220           if ((newval & CANCELTYPE_BITMASK) != 0)
 221             /* Run the registered destructors and terminate the thread.  */
 222             __do_cancel ();
 223
 224           break;
 225         }
 226
 227       oldval = curval;
 228     }
 229 }
 230 #endif
 231
 232
 233 #ifdef SIGSETXID
 234 struct xid_command *__xidcmd attribute_hidden;
 235
 236 /* We use the SIGSETXID signal in the setuid, setgid, etc. implementations to
 237    tell each thread to call the respective setxid syscall on itself.  This is
 238    the handler.  */
 239 static void
 240 sighandler_setxid (int sig, siginfo_t *si, void *ctx)
 241 {
 242   /* Determine the process ID.  It might be negative if the thread is
 243      in the middle of a fork() call.  */
 244   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
 245   int result;
 246   if (__glibc_unlikely (pid < 0))
 247     pid = -pid;
 248
 249   /* Safety check.  It would be possible to call this function for
 250      other signals and send a signal from another process.  This is not
 251      correct and might even be a security problem.  Try to catch as
 252      many incorrect invocations as possible.  */
 253   if (sig != SIGSETXID
 254       || si->si_pid != pid
 255       || si->si_code != SI_TKILL)
 256     return;
 257
 258   INTERNAL_SYSCALL_DECL (err);
 259   result = INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
 260                                  __xidcmd->id[1], __xidcmd->id[2]);
 261   int error = 0;
 262   if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
 263     error = INTERNAL_SYSCALL_ERRNO (result, err);
 264   __nptl_setxid_error (__xidcmd, error);
 265
 266   /* Reset the SETXID flag.  */
 267   struct pthread *self = THREAD_SELF;
 268   int flags, newval;
 269   do
 270     {
 271       flags = THREAD_GETMEM (self, cancelhandling);
 272       newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
 273                                           flags & ~SETXID_BITMASK, flags);
 274     }
 275   while (flags != newval);
 276
 277   /* And release the futex.  */
 278   self->setxid_futex = 1;
 279   lll_futex_wake (&self->setxid_futex, 1, LLL_PRIVATE);
 280
 281   if (atomic_decrement_val (&__xidcmd->cntr) == 0)
 282     lll_futex_wake (&__xidcmd->cntr, 1, LLL_PRIVATE);
 283 }
 284 #endif
 285
 286
 287 /* When using __thread for this, we do it in libc so as not
 288    to give libpthread its own TLS segment just for this.  */
 289 extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
 290
 291
 292 /* This can be set by the debugger before initialization is complete.  */
 293 static bool __nptl_initial_report_events __attribute_used__;
 294
 295 void
 296 __pthread_initialize_minimal_internal (void)
 297 {
 298 #ifndef SHARED
 299   /* Unlike in the dynamically linked case the dynamic linker has not
 300      taken care of initializing the TLS data structures.  */
 301   __libc_setup_tls (TLS_TCB_SIZE, TLS_TCB_ALIGN);
 302
 303   /* We must prevent gcc from being clever and move any of the
 304      following code ahead of the __libc_setup_tls call.  This function
 305      will initialize the thread register which is subsequently
 306      used.  */
 307   __asm __volatile ("");
 308 #endif
 309
 310   /* Minimal initialization of the thread descriptor.  */
 311   struct pthread *pd = THREAD_SELF;
 312 #ifdef __NR_set_tid_address
 313   INTERNAL_SYSCALL_DECL (err);
 314   pd->pid = pd->tid = INTERNAL_SYSCALL (set_tid_address, err, 1, &pd->tid);
 315 #endif
 316   THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
 317   THREAD_SETMEM (pd, user_stack, true);
 318   if (LLL_LOCK_INITIALIZER != 0)
 319     THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
 320 #if HP_TIMING_AVAIL
 321   THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
 322 #endif
 323
 324   /* Initialize the robust mutex data.  */
 325 #ifdef __PTHREAD_MUTEX_HAVE_PREV
 326   pd->robust_prev = &pd->robust_head;
 327 #endif
 328   pd->robust_head.list = &pd->robust_head;
 329 #ifdef __NR_set_robust_list
 330   pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
 331                                   - offsetof (pthread_mutex_t,
 332                                               __data.__list.__next));
 333   int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
 334                               sizeof (struct robust_list_head));
 335   if (INTERNAL_SYSCALL_ERROR_P (res, err))
 336 #endif
 337     set_robust_list_not_avail ();
 338
 339 #ifdef __NR_futex
 340 # ifndef __ASSUME_PRIVATE_FUTEX
 341   /* Private futexes are always used (at least internally) so that
 342      doing the test once this early is beneficial.  */
 343   {
 344     int word = 0;
 345     word = INTERNAL_SYSCALL (futex, err, 3, &word,
 346                             FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1);
 347     if (!INTERNAL_SYSCALL_ERROR_P (word, err))
 348       THREAD_SETMEM (pd, header.private_futex, FUTEX_PRIVATE_FLAG);
 349   }
 350
 351   /* Private futexes have been introduced earlier than the
 352      FUTEX_CLOCK_REALTIME flag.  We don't have to run the test if we
 353      know the former are not supported.  This also means we know the
 354      kernel will return ENOSYS for unknown operations.  */
 355   if (THREAD_GETMEM (pd, header.private_futex) != 0)
 356 # endif
 357 # ifndef __ASSUME_FUTEX_CLOCK_REALTIME
 358     {
 359       int word = 0;
 360       /* NB: the syscall actually takes six parameters.  The last is the
 361          bit mask.  But since we will not actually wait at all the value
 362          is irrelevant.  Given that passing six parameters is difficult
 363          on some architectures we just pass whatever random value the
 364          calling convention calls for to the kernel.  It causes no harm.  */
 365       word = INTERNAL_SYSCALL (futex, err, 5, &word,
 366                                FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME
 367                                | FUTEX_PRIVATE_FLAG, 1, NULL, 0);
 368       assert (INTERNAL_SYSCALL_ERROR_P (word, err));
 369       if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS)
 370         __set_futex_clock_realtime ();
 371     }
 372 # endif
 373 #endif
 374
 375   /* Set initial thread's stack block from 0 up to __libc_stack_end.
 376      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
 377      purposes this is good enough.  */
 378   THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
 379
 380   /* Initialize the list of all running threads with the main thread.  */
 381   INIT_LIST_HEAD (&__stack_user);
 382   list_add (&pd->list, &__stack_user);
 383
 384   /* Before initializing __stack_user, the debugger could not find us and
 385      had to set __nptl_initial_report_events.  Propagate its setting.  */
 386   THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
 387
 388 #if defined SIGCANCEL || defined SIGSETXID
 389   struct sigaction sa;
 390   __sigemptyset (&sa.sa_mask);
 391
 392 # ifdef SIGCANCEL
 393   /* Install the cancellation signal handler.  If for some reason we
 394      cannot install the handler we do not abort.  Maybe we should, but
 395      it is only asynchronous cancellation which is affected.  */
 396   sa.sa_sigaction = sigcancel_handler;
 397   sa.sa_flags = SA_SIGINFO;
 398   (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
 399 # endif
 400
 401 # ifdef SIGSETXID
 402   /* Install the handle to change the threads' uid/gid.  */
 403   sa.sa_sigaction = sighandler_setxid;
 404   sa.sa_flags = SA_SIGINFO | SA_RESTART;
 405   (void) __libc_sigaction (SIGSETXID, &sa, NULL);
 406 # endif
 407
 408   /* The parent process might have left the signals blocked.  Just in
 409      case, unblock it.  We reuse the signal mask in the sigaction
 410      structure.  It is already cleared.  */
 411 # ifdef SIGCANCEL
 412   __sigaddset (&sa.sa_mask, SIGCANCEL);
 413 # endif
 414 # ifdef SIGSETXID
 415   __sigaddset (&sa.sa_mask, SIGSETXID);
 416 # endif
 417   (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
 418                            NULL, _NSIG / 8);
 419 #endif
 420
 421   /* Get the size of the static and alignment requirements for the TLS
 422      block.  */
 423   size_t static_tls_align;
 424   _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
 425
 426   /* Make sure the size takes all the alignments into account.  */
 427   if (STACK_ALIGN > static_tls_align)
 428     static_tls_align = STACK_ALIGN;
 429   __static_tls_align_m1 = static_tls_align - 1;
 430
 431   __static_tls_size = roundup (__static_tls_size, static_tls_align);
 432
 433   /* Determine the default allowed stack size.  This is the size used
 434      in case the user does not specify one.  */
 435   struct rlimit limit;
 436   if (__getrlimit (RLIMIT_STACK, &limit) != 0
 437       || limit.rlim_cur == RLIM_INFINITY)
 438     /* The system limit is not usable.  Use an architecture-specific
 439        default.  */
 440     limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
 441   else if (limit.rlim_cur < PTHREAD_STACK_MIN)
 442     /* The system limit is unusably small.
 443        Use the minimal size acceptable.  */
 444     limit.rlim_cur = PTHREAD_STACK_MIN;
 445
 446   /* Make sure it meets the minimum size that allocate_stack
 447      (allocatestack.c) will demand, which depends on the page size.  */
 448   const uintptr_t pagesz = GLRO(dl_pagesize);
 449   const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
 450   if (limit.rlim_cur < minstack)
 451     limit.rlim_cur = minstack;
 452
 453   /* Round the resource limit up to page size.  */
 454   limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz);
 455   lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
 456   __default_pthread_attr.stacksize = limit.rlim_cur;
 457   __default_pthread_attr.guardsize = GLRO (dl_pagesize);
 458   lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
 459
 460 #ifdef SHARED
 461   /* Transfer the old value from the dynamic linker's internal location.  */
 462   *__libc_dl_error_tsd () = *(*GL(dl_error_catch_tsd)) ();
 463   GL(dl_error_catch_tsd) = &__libc_dl_error_tsd;
 464
 465   /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock,
 466      keep the lock count from the ld.so implementation.  */
 467   GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock;
 468   GL(dl_rtld_unlock_recursive) = (void *) __pthread_mutex_unlock;
 469   unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count;
 470   GL(dl_load_lock).mutex.__data.__count = 0;
 471   while (rtld_lock_count-- > 0)
 472     __pthread_mutex_lock (&GL(dl_load_lock).mutex);
 473
 474   GL(dl_make_stack_executable_hook) = &__make_stacks_executable;
 475 #endif
 476
 477   GL(dl_init_static_tls) = &__pthread_init_static_tls;
 478
 479   GL(dl_wait_lookup_done) = &__wait_lookup_done;
 480
 481   /* Register the fork generation counter with the libc.  */
 482 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
 483   __libc_multiple_threads_ptr =
 484 #endif
 485     __libc_pthread_init (&__fork_generation, __reclaim_stacks,
 486                          ptr_pthread_functions);
 487
 488   /* Determine whether the machine is SMP or not.  */
 489   __is_smp = is_smp_system ();
 490 }
 491 strong_alias (__pthread_initialize_minimal_internal,
 492               __pthread_initialize_minimal)
 493
 494
 495 size_t
 496 __pthread_get_minstack (const pthread_attr_t *attr)
 497 {
 498   struct pthread_attr *iattr = (struct pthread_attr *) attr;
 499
 500   return (GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN
 501           + iattr->guardsize);
 502 }