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 # ifdef SIGSETXID
 144     .ptr__nptl_setxid = __nptl_setxid,
 145 # endif
 146     /* For now only the stack cache needs to be freed.  */
 147     .ptr_freeres = nptl_freeres,
 148     .ptr_set_robust = __nptl_set_robust
 149   };
 150 # define ptr_pthread_functions &pthread_functions
 151 #else
 152 # define ptr_pthread_functions NULL
 153 #endif
 154
 155
 156 #ifdef SHARED
 157 /* This function is called indirectly from the freeres code in libc.  */
 158 static void
 159 __libc_freeres_fn_section
 160 nptl_freeres (void)
 161 {
 162   __unwind_freeres ();
 163   __free_stacks (0);
 164 }
 165
 166
 167 static
 168 #endif
 169 void
 170 __nptl_set_robust (struct pthread *self)
 171 {
 172 #ifdef __NR_set_robust_list
 173   INTERNAL_SYSCALL_DECL (err);
 174   INTERNAL_SYSCALL (set_robust_list, err, 2, &self->robust_head,
 175                     sizeof (struct robust_list_head));
 176 #endif
 177 }
 178
 179
 180 #ifdef SIGCANCEL
 181 /* For asynchronous cancellation we use a signal.  This is the handler.  */
 182 static void
 183 sigcancel_handler (int sig, siginfo_t *si, void *ctx)
 184 {
 185   /* Determine the process ID.  It might be negative if the thread is
 186      in the middle of a fork() call.  */
 187   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
 188   if (__glibc_unlikely (pid < 0))
 189     pid = -pid;
 190
 191   /* Safety check.  It would be possible to call this function for
 192      other signals and send a signal from another process.  This is not
 193      correct and might even be a security problem.  Try to catch as
 194      many incorrect invocations as possible.  */
 195   if (sig != SIGCANCEL
 196       || si->si_pid != pid
 197       || si->si_code != SI_TKILL)
 198     return;
 199
 200   struct pthread *self = THREAD_SELF;
 201
 202   int oldval = THREAD_GETMEM (self, cancelhandling);
 203   while (1)
 204     {
 205       /* We are canceled now.  When canceled by another thread this flag
 206          is already set but if the signal is directly send (internally or
 207          from another process) is has to be done here.  */
 208       int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
 209
 210       if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
 211         /* Already canceled or exiting.  */
 212         break;
 213
 214       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
 215                                               oldval);
 216       if (curval == oldval)
 217         {
 218           /* Set the return value.  */
 219           THREAD_SETMEM (self, result, PTHREAD_CANCELED);
 220
 221           /* Make sure asynchronous cancellation is still enabled.  */
 222           if ((newval & CANCELTYPE_BITMASK) != 0)
 223             /* Run the registered destructors and terminate the thread.  */
 224             __do_cancel ();
 225
 226           break;
 227         }
 228
 229       oldval = curval;
 230     }
 231 }
 232 #endif
 233
 234
 235 #ifdef SIGSETXID
 236 struct xid_command *__xidcmd attribute_hidden;
 237
 238 /* We use the SIGSETXID signal in the setuid, setgid, etc. implementations to
 239    tell each thread to call the respective setxid syscall on itself.  This is
 240    the handler.  */
 241 static void
 242 sighandler_setxid (int sig, siginfo_t *si, void *ctx)
 243 {
 244   /* Determine the process ID.  It might be negative if the thread is
 245      in the middle of a fork() call.  */
 246   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
 247   int result;
 248   if (__glibc_unlikely (pid < 0))
 249     pid = -pid;
 250
 251   /* Safety check.  It would be possible to call this function for
 252      other signals and send a signal from another process.  This is not
 253      correct and might even be a security problem.  Try to catch as
 254      many incorrect invocations as possible.  */
 255   if (sig != SIGSETXID
 256       || si->si_pid != pid
 257       || si->si_code != SI_TKILL)
 258     return;
 259
 260   INTERNAL_SYSCALL_DECL (err);
 261   result = INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
 262                                  __xidcmd->id[1], __xidcmd->id[2]);
 263   int error = 0;
 264   if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
 265     error = INTERNAL_SYSCALL_ERRNO (result, err);
 266   __nptl_setxid_error (__xidcmd, error);
 267
 268   /* Reset the SETXID flag.  */
 269   struct pthread *self = THREAD_SELF;
 270   int flags, newval;
 271   do
 272     {
 273       flags = THREAD_GETMEM (self, cancelhandling);
 274       newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
 275                                           flags & ~SETXID_BITMASK, flags);
 276     }
 277   while (flags != newval);
 278
 279   /* And release the futex.  */
 280   self->setxid_futex = 1;
 281   lll_futex_wake (&self->setxid_futex, 1, LLL_PRIVATE);
 282
 283   if (atomic_decrement_val (&__xidcmd->cntr) == 0)
 284     lll_futex_wake (&__xidcmd->cntr, 1, LLL_PRIVATE);
 285 }
 286 #endif
 287
 288
 289 /* When using __thread for this, we do it in libc so as not
 290    to give libpthread its own TLS segment just for this.  */
 291 extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
 292
 293
 294 /* This can be set by the debugger before initialization is complete.  */
 295 static bool __nptl_initial_report_events __attribute_used__;
 296
 297 void
 298 __pthread_initialize_minimal_internal (void)
 299 {
 300 #ifndef SHARED
 301   /* Unlike in the dynamically linked case the dynamic linker has not
 302      taken care of initializing the TLS data structures.  */
 303   __libc_setup_tls (TLS_TCB_SIZE, TLS_TCB_ALIGN);
 304
 305   /* We must prevent gcc from being clever and move any of the
 306      following code ahead of the __libc_setup_tls call.  This function
 307      will initialize the thread register which is subsequently
 308      used.  */
 309   __asm __volatile ("");
 310 #endif
 311
 312   /* Minimal initialization of the thread descriptor.  */
 313   struct pthread *pd = THREAD_SELF;
 314 #ifdef __NR_set_tid_address
 315   INTERNAL_SYSCALL_DECL (err);
 316   pd->pid = pd->tid = INTERNAL_SYSCALL (set_tid_address, err, 1, &pd->tid);
 317 #endif
 318   THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
 319   THREAD_SETMEM (pd, user_stack, true);
 320   if (LLL_LOCK_INITIALIZER != 0)
 321     THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
 322 #if HP_TIMING_AVAIL
 323   THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
 324 #endif
 325
 326   /* Initialize the robust mutex data.  */
 327 #ifdef __PTHREAD_MUTEX_HAVE_PREV
 328   pd->robust_prev = &pd->robust_head;
 329 #endif
 330   pd->robust_head.list = &pd->robust_head;
 331 #ifdef __NR_set_robust_list
 332   pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
 333                                   - offsetof (pthread_mutex_t,
 334                                               __data.__list.__next));
 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 #ifdef __NR_futex
 342 # ifndef __ASSUME_PRIVATE_FUTEX
 343   /* Private futexes are always used (at least internally) so that
 344      doing the test once this early is beneficial.  */
 345   {
 346     int word = 0;
 347     word = INTERNAL_SYSCALL (futex, err, 3, &word,
 348                             FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1);
 349     if (!INTERNAL_SYSCALL_ERROR_P (word, err))
 350       THREAD_SETMEM (pd, header.private_futex, FUTEX_PRIVATE_FLAG);
 351   }
 352
 353   /* Private futexes have been introduced earlier than the
 354      FUTEX_CLOCK_REALTIME flag.  We don't have to run the test if we
 355      know the former are not supported.  This also means we know the
 356      kernel will return ENOSYS for unknown operations.  */
 357   if (THREAD_GETMEM (pd, header.private_futex) != 0)
 358 # endif
 359 # ifndef __ASSUME_FUTEX_CLOCK_REALTIME
 360     {
 361       int word = 0;
 362       /* NB: the syscall actually takes six parameters.  The last is the
 363          bit mask.  But since we will not actually wait at all the value
 364          is irrelevant.  Given that passing six parameters is difficult
 365          on some architectures we just pass whatever random value the
 366          calling convention calls for to the kernel.  It causes no harm.  */
 367       word = INTERNAL_SYSCALL (futex, err, 5, &word,
 368                                FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME
 369                                | FUTEX_PRIVATE_FLAG, 1, NULL, 0);
 370       assert (INTERNAL_SYSCALL_ERROR_P (word, err));
 371       if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS)
 372         __set_futex_clock_realtime ();
 373     }
 374 # endif
 375 #endif
 376
 377   /* Set initial thread's stack block from 0 up to __libc_stack_end.
 378      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
 379      purposes this is good enough.  */
 380   THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
 381
 382   /* Initialize the list of all running threads with the main thread.  */
 383   INIT_LIST_HEAD (&__stack_user);
 384   list_add (&pd->list, &__stack_user);
 385
 386   /* Before initializing __stack_user, the debugger could not find us and
 387      had to set __nptl_initial_report_events.  Propagate its setting.  */
 388   THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
 389
 390 #if defined SIGCANCEL || defined SIGSETXID
 391   struct sigaction sa;
 392   __sigemptyset (&sa.sa_mask);
 393
 394 # ifdef SIGCANCEL
 395   /* Install the cancellation signal handler.  If for some reason we
 396      cannot install the handler we do not abort.  Maybe we should, but
 397      it is only asynchronous cancellation which is affected.  */
 398   sa.sa_sigaction = sigcancel_handler;
 399   sa.sa_flags = SA_SIGINFO;
 400   (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
 401 # endif
 402
 403 # ifdef SIGSETXID
 404   /* Install the handle to change the threads' uid/gid.  */
 405   sa.sa_sigaction = sighandler_setxid;
 406   sa.sa_flags = SA_SIGINFO | SA_RESTART;
 407   (void) __libc_sigaction (SIGSETXID, &sa, NULL);
 408 # endif
 409
 410   /* The parent process might have left the signals blocked.  Just in
 411      case, unblock it.  We reuse the signal mask in the sigaction
 412      structure.  It is already cleared.  */
 413 # ifdef SIGCANCEL
 414   __sigaddset (&sa.sa_mask, SIGCANCEL);
 415 # endif
 416 # ifdef SIGSETXID
 417   __sigaddset (&sa.sa_mask, SIGSETXID);
 418 # endif
 419   (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
 420                            NULL, _NSIG / 8);
 421 #endif
 422
 423   /* Get the size of the static and alignment requirements for the TLS
 424      block.  */
 425   size_t static_tls_align;
 426   _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
 427
 428   /* Make sure the size takes all the alignments into account.  */
 429   if (STACK_ALIGN > static_tls_align)
 430     static_tls_align = STACK_ALIGN;
 431   __static_tls_align_m1 = static_tls_align - 1;
 432
 433   __static_tls_size = roundup (__static_tls_size, static_tls_align);
 434
 435   /* Determine the default allowed stack size.  This is the size used
 436      in case the user does not specify one.  */
 437   struct rlimit limit;
 438   if (__getrlimit (RLIMIT_STACK, &limit) != 0
 439       || limit.rlim_cur == RLIM_INFINITY)
 440     /* The system limit is not usable.  Use an architecture-specific
 441        default.  */
 442     limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
 443   else if (limit.rlim_cur < PTHREAD_STACK_MIN)
 444     /* The system limit is unusably small.
 445        Use the minimal size acceptable.  */
 446     limit.rlim_cur = PTHREAD_STACK_MIN;
 447
 448   /* Make sure it meets the minimum size that allocate_stack
 449      (allocatestack.c) will demand, which depends on the page size.  */
 450   const uintptr_t pagesz = GLRO(dl_pagesize);
 451   const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
 452   if (limit.rlim_cur < minstack)
 453     limit.rlim_cur = minstack;
 454
 455   /* Round the resource limit up to page size.  */
 456   limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz);
 457   lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
 458   __default_pthread_attr.stacksize = limit.rlim_cur;
 459   __default_pthread_attr.guardsize = GLRO (dl_pagesize);
 460   lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
 461
 462 #ifdef SHARED
 463   /* Transfer the old value from the dynamic linker's internal location.  */
 464   *__libc_dl_error_tsd () = *(*GL(dl_error_catch_tsd)) ();
 465   GL(dl_error_catch_tsd) = &__libc_dl_error_tsd;
 466
 467   /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock,
 468      keep the lock count from the ld.so implementation.  */
 469   GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock;
 470   GL(dl_rtld_unlock_recursive) = (void *) __pthread_mutex_unlock;
 471   unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count;
 472   GL(dl_load_lock).mutex.__data.__count = 0;
 473   while (rtld_lock_count-- > 0)
 474     __pthread_mutex_lock (&GL(dl_load_lock).mutex);
 475
 476   GL(dl_make_stack_executable_hook) = &__make_stacks_executable;
 477 #endif
 478
 479   GL(dl_init_static_tls) = &__pthread_init_static_tls;
 480
 481   GL(dl_wait_lookup_done) = &__wait_lookup_done;
 482
 483   /* Register the fork generation counter with the libc.  */
 484 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
 485   __libc_multiple_threads_ptr =
 486 #endif
 487     __libc_pthread_init (&__fork_generation, __reclaim_stacks,
 488                          ptr_pthread_functions);
 489
 490   /* Determine whether the machine is SMP or not.  */
 491   __is_smp = is_smp_system ();
 492 }
 493 strong_alias (__pthread_initialize_minimal_internal,
 494               __pthread_initialize_minimal)
 495
 496
 497 size_t
 498 __pthread_get_minstack (const pthread_attr_t *attr)
 499 {
 500   struct pthread_attr *iattr = (struct pthread_attr *) attr;
 501
 502   return (GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN
 503           + iattr->guardsize);
 504 }