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 #include <pthread-pids.h>
  40
  41 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
  42 /* Pointer to the corresponding variable in libc.  */
  43 int *__libc_multiple_threads_ptr attribute_hidden;
  44 #endif
  45
  46 /* Size and alignment of static TLS block.  */
  47 size_t __static_tls_size;
  48 size_t __static_tls_align_m1;
  49
  50 #ifndef __ASSUME_SET_ROBUST_LIST
  51 /* Negative if we do not have the system call and we can use it.  */
  52 int __set_robust_list_avail;
  53 # define set_robust_list_not_avail() \
  54   __set_robust_list_avail = -1
  55 #else
  56 # define set_robust_list_not_avail() do { } while (0)
  57 #endif
  58
  59 #ifndef __ASSUME_FUTEX_CLOCK_REALTIME
  60 /* Nonzero if we do not have FUTEX_CLOCK_REALTIME.  */
  61 int __have_futex_clock_realtime;
  62 # define __set_futex_clock_realtime() \
  63   __have_futex_clock_realtime = 1
  64 #else
  65 #define __set_futex_clock_realtime() do { } while (0)
  66 #endif
  67
  68 /* Version of the library, used in libthread_db to detect mismatches.  */
  69 static const char nptl_version[] __attribute_used__ = VERSION;
  70
  71
  72 #ifndef SHARED
  73 extern void __libc_setup_tls (size_t tcbsize, size_t tcbalign);
  74 #endif
  75
  76 #ifdef SHARED
  77 static
  78 #else
  79 extern
  80 #endif
  81 void __nptl_set_robust (struct pthread *);
  82
  83 #ifdef SHARED
  84 static void nptl_freeres (void);
  85
  86
  87 static const struct pthread_functions pthread_functions =
  88   {
  89     .ptr_pthread_attr_destroy = __pthread_attr_destroy,
  90 # if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
  91     .ptr___pthread_attr_init_2_0 = __pthread_attr_init_2_0,
  92 # endif
  93     .ptr___pthread_attr_init_2_1 = __pthread_attr_init_2_1,
  94     .ptr_pthread_attr_getdetachstate = __pthread_attr_getdetachstate,
  95     .ptr_pthread_attr_setdetachstate = __pthread_attr_setdetachstate,
  96     .ptr_pthread_attr_getinheritsched = __pthread_attr_getinheritsched,
  97     .ptr_pthread_attr_setinheritsched = __pthread_attr_setinheritsched,
  98     .ptr_pthread_attr_getschedparam = __pthread_attr_getschedparam,
  99     .ptr_pthread_attr_setschedparam = __pthread_attr_setschedparam,
 100     .ptr_pthread_attr_getschedpolicy = __pthread_attr_getschedpolicy,
 101     .ptr_pthread_attr_setschedpolicy = __pthread_attr_setschedpolicy,
 102     .ptr_pthread_attr_getscope = __pthread_attr_getscope,
 103     .ptr_pthread_attr_setscope = __pthread_attr_setscope,
 104     .ptr_pthread_condattr_destroy = __pthread_condattr_destroy,
 105     .ptr_pthread_condattr_init = __pthread_condattr_init,
 106     .ptr___pthread_cond_broadcast = __pthread_cond_broadcast,
 107     .ptr___pthread_cond_destroy = __pthread_cond_destroy,
 108     .ptr___pthread_cond_init = __pthread_cond_init,
 109     .ptr___pthread_cond_signal = __pthread_cond_signal,
 110     .ptr___pthread_cond_wait = __pthread_cond_wait,
 111     .ptr___pthread_cond_timedwait = __pthread_cond_timedwait,
 112 # if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_3_2)
 113     .ptr___pthread_cond_broadcast_2_0 = __pthread_cond_broadcast_2_0,
 114     .ptr___pthread_cond_destroy_2_0 = __pthread_cond_destroy_2_0,
 115     .ptr___pthread_cond_init_2_0 = __pthread_cond_init_2_0,
 116     .ptr___pthread_cond_signal_2_0 = __pthread_cond_signal_2_0,
 117     .ptr___pthread_cond_wait_2_0 = __pthread_cond_wait_2_0,
 118     .ptr___pthread_cond_timedwait_2_0 = __pthread_cond_timedwait_2_0,
 119 # endif
 120     .ptr_pthread_equal = __pthread_equal,
 121     .ptr___pthread_exit = __pthread_exit,
 122     .ptr_pthread_getschedparam = __pthread_getschedparam,
 123     .ptr_pthread_setschedparam = __pthread_setschedparam,
 124     .ptr_pthread_mutex_destroy = __pthread_mutex_destroy,
 125     .ptr_pthread_mutex_init = __pthread_mutex_init,
 126     .ptr_pthread_mutex_lock = __pthread_mutex_lock,
 127     .ptr_pthread_mutex_unlock = __pthread_mutex_unlock,
 128     .ptr_pthread_self = __pthread_self,
 129     .ptr_pthread_setcancelstate = __pthread_setcancelstate,
 130     .ptr_pthread_setcanceltype = __pthread_setcanceltype,
 131     .ptr___pthread_cleanup_upto = __pthread_cleanup_upto,
 132     .ptr___pthread_once = __pthread_once,
 133     .ptr___pthread_rwlock_rdlock = __pthread_rwlock_rdlock,
 134     .ptr___pthread_rwlock_wrlock = __pthread_rwlock_wrlock,
 135     .ptr___pthread_rwlock_unlock = __pthread_rwlock_unlock,
 136     .ptr___pthread_key_create = __pthread_key_create,
 137     .ptr___pthread_getspecific = __pthread_getspecific,
 138     .ptr___pthread_setspecific = __pthread_setspecific,
 139     .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer,
 140     .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore,
 141     .ptr_nthreads = &__nptl_nthreads,
 142     .ptr___pthread_unwind = &__pthread_unwind,
 143     .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd,
 144 # ifdef SIGSETXID
 145     .ptr__nptl_setxid = __nptl_setxid,
 146 # endif
 147     /* For now only the stack cache needs to be freed.  */
 148     .ptr_freeres = nptl_freeres,
 149     .ptr_set_robust = __nptl_set_robust
 150   };
 151 # define ptr_pthread_functions &pthread_functions
 152 #else
 153 # define ptr_pthread_functions NULL
 154 #endif
 155
 156
 157 #ifdef SHARED
 158 /* This function is called indirectly from the freeres code in libc.  */
 159 static void
 160 __libc_freeres_fn_section
 161 nptl_freeres (void)
 162 {
 163   __unwind_freeres ();
 164   __free_stacks (0);
 165 }
 166
 167
 168 static
 169 #endif
 170 void
 171 __nptl_set_robust (struct pthread *self)
 172 {
 173 #ifdef __NR_set_robust_list
 174   INTERNAL_SYSCALL_DECL (err);
 175   INTERNAL_SYSCALL (set_robust_list, err, 2, &self->robust_head,
 176                     sizeof (struct robust_list_head));
 177 #endif
 178 }
 179
 180
 181 #ifdef SIGCANCEL
 182 /* For asynchronous cancellation we use a signal.  This is the handler.  */
 183 static void
 184 sigcancel_handler (int sig, siginfo_t *si, void *ctx)
 185 {
 186   /* Determine the process ID.  It might be negative if the thread is
 187      in the middle of a fork() call.  */
 188   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
 189   if (__glibc_unlikely (pid < 0))
 190     pid = -pid;
 191
 192   /* Safety check.  It would be possible to call this function for
 193      other signals and send a signal from another process.  This is not
 194      correct and might even be a security problem.  Try to catch as
 195      many incorrect invocations as possible.  */
 196   if (sig != SIGCANCEL
 197       || si->si_pid != pid
 198       || si->si_code != SI_TKILL)
 199     return;
 200
 201   struct pthread *self = THREAD_SELF;
 202
 203   int oldval = THREAD_GETMEM (self, cancelhandling);
 204   while (1)
 205     {
 206       /* We are canceled now.  When canceled by another thread this flag
 207          is already set but if the signal is directly send (internally or
 208          from another process) is has to be done here.  */
 209       int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
 210
 211       if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
 212         /* Already canceled or exiting.  */
 213         break;
 214
 215       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
 216                                               oldval);
 217       if (curval == oldval)
 218         {
 219           /* Set the return value.  */
 220           THREAD_SETMEM (self, result, PTHREAD_CANCELED);
 221
 222           /* Make sure asynchronous cancellation is still enabled.  */
 223           if ((newval & CANCELTYPE_BITMASK) != 0)
 224             /* Run the registered destructors and terminate the thread.  */
 225             __do_cancel ();
 226
 227           break;
 228         }
 229
 230       oldval = curval;
 231     }
 232 }
 233 #endif
 234
 235
 236 #ifdef SIGSETXID
 237 struct xid_command *__xidcmd attribute_hidden;
 238
 239 /* We use the SIGSETXID signal in the setuid, setgid, etc. implementations to
 240    tell each thread to call the respective setxid syscall on itself.  This is
 241    the handler.  */
 242 static void
 243 sighandler_setxid (int sig, siginfo_t *si, void *ctx)
 244 {
 245   /* Determine the process ID.  It might be negative if the thread is
 246      in the middle of a fork() call.  */
 247   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
 248   int result;
 249   if (__glibc_unlikely (pid < 0))
 250     pid = -pid;
 251
 252   /* Safety check.  It would be possible to call this function for
 253      other signals and send a signal from another process.  This is not
 254      correct and might even be a security problem.  Try to catch as
 255      many incorrect invocations as possible.  */
 256   if (sig != SIGSETXID
 257       || si->si_pid != pid
 258       || si->si_code != SI_TKILL)
 259     return;
 260
 261   INTERNAL_SYSCALL_DECL (err);
 262   result = INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
 263                                  __xidcmd->id[1], __xidcmd->id[2]);
 264   int error = 0;
 265   if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
 266     error = INTERNAL_SYSCALL_ERRNO (result, err);
 267   __nptl_setxid_error (__xidcmd, error);
 268
 269   /* Reset the SETXID flag.  */
 270   struct pthread *self = THREAD_SELF;
 271   int flags, newval;
 272   do
 273     {
 274       flags = THREAD_GETMEM (self, cancelhandling);
 275       newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
 276                                           flags & ~SETXID_BITMASK, flags);
 277     }
 278   while (flags != newval);
 279
 280   /* And release the futex.  */
 281   self->setxid_futex = 1;
 282   lll_futex_wake (&self->setxid_futex, 1, LLL_PRIVATE);
 283
 284   if (atomic_decrement_val (&__xidcmd->cntr) == 0)
 285     lll_futex_wake (&__xidcmd->cntr, 1, LLL_PRIVATE);
 286 }
 287 #endif
 288
 289
 290 /* When using __thread for this, we do it in libc so as not
 291    to give libpthread its own TLS segment just for this.  */
 292 extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
 293
 294
 295 /* This can be set by the debugger before initialization is complete.  */
 296 static bool __nptl_initial_report_events __attribute_used__;
 297
 298 void
 299 __pthread_initialize_minimal_internal (void)
 300 {
 301 #ifndef SHARED
 302   /* Unlike in the dynamically linked case the dynamic linker has not
 303      taken care of initializing the TLS data structures.  */
 304   __libc_setup_tls (TLS_TCB_SIZE, TLS_TCB_ALIGN);
 305
 306   /* We must prevent gcc from being clever and move any of the
 307      following code ahead of the __libc_setup_tls call.  This function
 308      will initialize the thread register which is subsequently
 309      used.  */
 310   __asm __volatile ("");
 311 #endif
 312
 313   /* Minimal initialization of the thread descriptor.  */
 314   struct pthread *pd = THREAD_SELF;
 315   __pthread_initialize_pids (pd);
 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   {
 326 #ifdef __PTHREAD_MUTEX_HAVE_PREV
 327     pd->robust_prev = &pd->robust_head;
 328 #endif
 329     pd->robust_head.list = &pd->robust_head;
 330 #ifdef __NR_set_robust_list
 331     pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
 332                                     - offsetof (pthread_mutex_t,
 333                                                 __data.__list.__next));
 334     INTERNAL_SYSCALL_DECL (err);
 335     int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
 336                                 sizeof (struct robust_list_head));
 337     if (INTERNAL_SYSCALL_ERROR_P (res, err))
 338 #endif
 339       set_robust_list_not_avail ();
 340   }
 341
 342 #ifdef __NR_futex
 343 # ifndef __ASSUME_PRIVATE_FUTEX
 344   /* Private futexes are always used (at least internally) so that
 345      doing the test once this early is beneficial.  */
 346   {
 347     int word = 0;
 348     INTERNAL_SYSCALL_DECL (err);
 349     word = INTERNAL_SYSCALL (futex, err, 3, &word,
 350                             FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1);
 351     if (!INTERNAL_SYSCALL_ERROR_P (word, err))
 352       THREAD_SETMEM (pd, header.private_futex, FUTEX_PRIVATE_FLAG);
 353   }
 354
 355   /* Private futexes have been introduced earlier than the
 356      FUTEX_CLOCK_REALTIME flag.  We don't have to run the test if we
 357      know the former are not supported.  This also means we know the
 358      kernel will return ENOSYS for unknown operations.  */
 359   if (THREAD_GETMEM (pd, header.private_futex) != 0)
 360 # endif
 361 # ifndef __ASSUME_FUTEX_CLOCK_REALTIME
 362     {
 363       int word = 0;
 364       /* NB: the syscall actually takes six parameters.  The last is the
 365          bit mask.  But since we will not actually wait at all the value
 366          is irrelevant.  Given that passing six parameters is difficult
 367          on some architectures we just pass whatever random value the
 368          calling convention calls for to the kernel.  It causes no harm.  */
 369       INTERNAL_SYSCALL_DECL (err);
 370       word = INTERNAL_SYSCALL (futex, err, 5, &word,
 371                                FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME
 372                                | FUTEX_PRIVATE_FLAG, 1, NULL, 0);
 373       assert (INTERNAL_SYSCALL_ERROR_P (word, err));
 374       if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS)
 375         __set_futex_clock_realtime ();
 376     }
 377 # endif
 378 #endif
 379
 380   /* Set initial thread's stack block from 0 up to __libc_stack_end.
 381      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
 382      purposes this is good enough.  */
 383   THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
 384
 385   /* Initialize the list of all running threads with the main thread.  */
 386   INIT_LIST_HEAD (&__stack_user);
 387   list_add (&pd->list, &__stack_user);
 388
 389   /* Before initializing __stack_user, the debugger could not find us and
 390      had to set __nptl_initial_report_events.  Propagate its setting.  */
 391   THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
 392
 393 #if defined SIGCANCEL || defined SIGSETXID
 394   struct sigaction sa;
 395   __sigemptyset (&sa.sa_mask);
 396
 397 # ifdef SIGCANCEL
 398   /* Install the cancellation signal handler.  If for some reason we
 399      cannot install the handler we do not abort.  Maybe we should, but
 400      it is only asynchronous cancellation which is affected.  */
 401   sa.sa_sigaction = sigcancel_handler;
 402   sa.sa_flags = SA_SIGINFO;
 403   (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
 404 # endif
 405
 406 # ifdef SIGSETXID
 407   /* Install the handle to change the threads' uid/gid.  */
 408   sa.sa_sigaction = sighandler_setxid;
 409   sa.sa_flags = SA_SIGINFO | SA_RESTART;
 410   (void) __libc_sigaction (SIGSETXID, &sa, NULL);
 411 # endif
 412
 413   /* The parent process might have left the signals blocked.  Just in
 414      case, unblock it.  We reuse the signal mask in the sigaction
 415      structure.  It is already cleared.  */
 416 # ifdef SIGCANCEL
 417   __sigaddset (&sa.sa_mask, SIGCANCEL);
 418 # endif
 419 # ifdef SIGSETXID
 420   __sigaddset (&sa.sa_mask, SIGSETXID);
 421 # endif
 422   {
 423     INTERNAL_SYSCALL_DECL (err);
 424     (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
 425                              NULL, _NSIG / 8);
 426   }
 427 #endif
 428
 429   /* Get the size of the static and alignment requirements for the TLS
 430      block.  */
 431   size_t static_tls_align;
 432   _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
 433
 434   /* Make sure the size takes all the alignments into account.  */
 435   if (STACK_ALIGN > static_tls_align)
 436     static_tls_align = STACK_ALIGN;
 437   __static_tls_align_m1 = static_tls_align - 1;
 438
 439   __static_tls_size = roundup (__static_tls_size, static_tls_align);
 440
 441   /* Determine the default allowed stack size.  This is the size used
 442      in case the user does not specify one.  */
 443   struct rlimit limit;
 444   if (__getrlimit (RLIMIT_STACK, &limit) != 0
 445       || limit.rlim_cur == RLIM_INFINITY)
 446     /* The system limit is not usable.  Use an architecture-specific
 447        default.  */
 448     limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
 449   else if (limit.rlim_cur < PTHREAD_STACK_MIN)
 450     /* The system limit is unusably small.
 451        Use the minimal size acceptable.  */
 452     limit.rlim_cur = PTHREAD_STACK_MIN;
 453
 454   /* Make sure it meets the minimum size that allocate_stack
 455      (allocatestack.c) will demand, which depends on the page size.  */
 456   const uintptr_t pagesz = GLRO(dl_pagesize);
 457   const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
 458   if (limit.rlim_cur < minstack)
 459     limit.rlim_cur = minstack;
 460
 461   /* Round the resource limit up to page size.  */
 462   limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz);
 463   lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
 464   __default_pthread_attr.stacksize = limit.rlim_cur;
 465   __default_pthread_attr.guardsize = GLRO (dl_pagesize);
 466   lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
 467
 468 #ifdef SHARED
 469   /* Transfer the old value from the dynamic linker's internal location.  */
 470   *__libc_dl_error_tsd () = *(*GL(dl_error_catch_tsd)) ();
 471   GL(dl_error_catch_tsd) = &__libc_dl_error_tsd;
 472
 473   /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock,
 474      keep the lock count from the ld.so implementation.  */
 475   GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock;
 476   GL(dl_rtld_unlock_recursive) = (void *) __pthread_mutex_unlock;
 477   unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count;
 478   GL(dl_load_lock).mutex.__data.__count = 0;
 479   while (rtld_lock_count-- > 0)
 480     __pthread_mutex_lock (&GL(dl_load_lock).mutex);
 481
 482   GL(dl_make_stack_executable_hook) = &__make_stacks_executable;
 483 #endif
 484
 485   GL(dl_init_static_tls) = &__pthread_init_static_tls;
 486
 487   GL(dl_wait_lookup_done) = &__wait_lookup_done;
 488
 489   /* Register the fork generation counter with the libc.  */
 490 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
 491   __libc_multiple_threads_ptr =
 492 #endif
 493     __libc_pthread_init (&__fork_generation, __reclaim_stacks,
 494                          ptr_pthread_functions);
 495
 496   /* Determine whether the machine is SMP or not.  */
 497   __is_smp = is_smp_system ();
 498 }
 499 strong_alias (__pthread_initialize_minimal_internal,
 500               __pthread_initialize_minimal)
 501
 502
 503 size_t
 504 __pthread_get_minstack (const pthread_attr_t *attr)
 505 {
 506   struct pthread_attr *iattr = (struct pthread_attr *) attr;
 507
 508   return (GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN
 509           + iattr->guardsize);
 510 }