nptl/init.c

   1 /* Copyright (C) 2002-2007, 2008, 2009 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <limits.h>
  23 #include <signal.h>
  24 #include <stdlib.h>
  25 #include <unistd.h>
  26 #include <sys/param.h>
  27 #include <sys/resource.h>
  28 #include <pthreadP.h>
  29 #include <atomic.h>
  30 #include <ldsodefs.h>
  31 #include <tls.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
  39
  40 /* Size and alignment of static TLS block.  */
  41 size_t __static_tls_size;
  42 size_t __static_tls_align_m1;
  43
  44 #ifndef __ASSUME_SET_ROBUST_LIST
  45 /* Negative if we do not have the system call and we can use it.  */
  46 int __set_robust_list_avail;
  47 # define set_robust_list_not_avail() \
  48   __set_robust_list_avail = -1
  49 #else
  50 # define set_robust_list_not_avail() do { } while (0)
  51 #endif
  52
  53 #ifndef __ASSUME_FUTEX_CLOCK_REALTIME
  54 /* Nonzero if we do not have FUTEX_CLOCK_REALTIME.  */
  55 int __have_futex_clock_realtime;
  56 # define __set_futex_clock_realtime() \
  57   __have_futex_clock_realtime = 1
  58 #else
  59 #define __set_futex_clock_realtime() do { } while (0)
  60 #endif
  61
  62 /* Version of the library, used in libthread_db to detect mismatches.  */
  63 static const char nptl_version[] __attribute_used__ = VERSION;
  64
  65
  66 #ifndef SHARED
  67 extern void __libc_setup_tls (size_t tcbsize, size_t tcbalign);
  68 #endif
  69
  70 static void nptl_freeres (void);
  71
  72
  73 #ifdef SHARED
  74 static const struct pthread_functions pthread_functions =
  75   {
  76     .ptr_pthread_attr_destroy = __pthread_attr_destroy,
  77 # if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
  78     .ptr___pthread_attr_init_2_0 = __pthread_attr_init_2_0,
  79 # endif
  80     .ptr___pthread_attr_init_2_1 = __pthread_attr_init_2_1,
  81     .ptr_pthread_attr_getdetachstate = __pthread_attr_getdetachstate,
  82     .ptr_pthread_attr_setdetachstate = __pthread_attr_setdetachstate,
  83     .ptr_pthread_attr_getinheritsched = __pthread_attr_getinheritsched,
  84     .ptr_pthread_attr_setinheritsched = __pthread_attr_setinheritsched,
  85     .ptr_pthread_attr_getschedparam = __pthread_attr_getschedparam,
  86     .ptr_pthread_attr_setschedparam = __pthread_attr_setschedparam,
  87     .ptr_pthread_attr_getschedpolicy = __pthread_attr_getschedpolicy,
  88     .ptr_pthread_attr_setschedpolicy = __pthread_attr_setschedpolicy,
  89     .ptr_pthread_attr_getscope = __pthread_attr_getscope,
  90     .ptr_pthread_attr_setscope = __pthread_attr_setscope,
  91     .ptr_pthread_condattr_destroy = __pthread_condattr_destroy,
  92     .ptr_pthread_condattr_init = __pthread_condattr_init,
  93     .ptr___pthread_cond_broadcast = __pthread_cond_broadcast,
  94     .ptr___pthread_cond_destroy = __pthread_cond_destroy,
  95     .ptr___pthread_cond_init = __pthread_cond_init,
  96     .ptr___pthread_cond_signal = __pthread_cond_signal,
  97     .ptr___pthread_cond_wait = __pthread_cond_wait,
  98     .ptr___pthread_cond_timedwait = __pthread_cond_timedwait,
  99 # if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_3_2)
 100     .ptr___pthread_cond_broadcast_2_0 = __pthread_cond_broadcast_2_0,
 101     .ptr___pthread_cond_destroy_2_0 = __pthread_cond_destroy_2_0,
 102     .ptr___pthread_cond_init_2_0 = __pthread_cond_init_2_0,
 103     .ptr___pthread_cond_signal_2_0 = __pthread_cond_signal_2_0,
 104     .ptr___pthread_cond_wait_2_0 = __pthread_cond_wait_2_0,
 105     .ptr___pthread_cond_timedwait_2_0 = __pthread_cond_timedwait_2_0,
 106 # endif
 107     .ptr_pthread_equal = __pthread_equal,
 108     .ptr___pthread_exit = __pthread_exit,
 109     .ptr_pthread_getschedparam = __pthread_getschedparam,
 110     .ptr_pthread_setschedparam = __pthread_setschedparam,
 111     .ptr_pthread_mutex_destroy = INTUSE(__pthread_mutex_destroy),
 112     .ptr_pthread_mutex_init = INTUSE(__pthread_mutex_init),
 113     .ptr_pthread_mutex_lock = INTUSE(__pthread_mutex_lock),
 114     .ptr_pthread_mutex_unlock = INTUSE(__pthread_mutex_unlock),
 115     .ptr_pthread_self = __pthread_self,
 116     .ptr_pthread_setcancelstate = __pthread_setcancelstate,
 117     .ptr_pthread_setcanceltype = __pthread_setcanceltype,
 118     .ptr___pthread_cleanup_upto = __pthread_cleanup_upto,
 119     .ptr___pthread_once = __pthread_once_internal,
 120     .ptr___pthread_rwlock_rdlock = __pthread_rwlock_rdlock_internal,
 121     .ptr___pthread_rwlock_wrlock = __pthread_rwlock_wrlock_internal,
 122     .ptr___pthread_rwlock_unlock = __pthread_rwlock_unlock_internal,
 123     .ptr___pthread_key_create = __pthread_key_create_internal,
 124     .ptr___pthread_getspecific = __pthread_getspecific_internal,
 125     .ptr___pthread_setspecific = __pthread_setspecific_internal,
 126     .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer,
 127     .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore,
 128     .ptr_nthreads = &__nptl_nthreads,
 129     .ptr___pthread_unwind = &__pthread_unwind,
 130     .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd,
 131     .ptr__nptl_setxid = __nptl_setxid,
 132     /* For now only the stack cache needs to be freed.  */
 133     .ptr_freeres = nptl_freeres
 134   };
 135 # define ptr_pthread_functions &pthread_functions
 136 #else
 137 # define ptr_pthread_functions NULL
 138 #endif
 139
 140
 141 /* This function is called indirectly from the freeres code in libc.  */
 142 static void
 143 __libc_freeres_fn_section
 144 nptl_freeres (void)
 145 {
 146 #ifdef SHARED
 147   __unwind_freeres ();
 148 #endif
 149   __free_stacks (0);
 150 }
 151
 152
 153 /* For asynchronous cancellation we use a signal.  This is the handler.  */
 154 static void
 155 sigcancel_handler (int sig, siginfo_t *si, void *ctx)
 156 {
 157 #ifdef __ASSUME_CORRECT_SI_PID
 158   /* Determine the process ID.  It might be negative if the thread is
 159      in the middle of a fork() call.  */
 160   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
 161   if (__builtin_expect (pid < 0, 0))
 162     pid = -pid;
 163 #endif
 164
 165   /* Safety check.  It would be possible to call this function for
 166      other signals and send a signal from another process.  This is not
 167      correct and might even be a security problem.  Try to catch as
 168      many incorrect invocations as possible.  */
 169   if (sig != SIGCANCEL
 170 #ifdef __ASSUME_CORRECT_SI_PID
 171       /* Kernels before 2.5.75 stored the thread ID and not the process
 172          ID in si_pid so we skip this test.  */
 173       || si->si_pid != pid
 174 #endif
 175       || si->si_code != SI_TKILL)
 176     return;
 177
 178   struct pthread *self = THREAD_SELF;
 179
 180   int oldval = THREAD_GETMEM (self, cancelhandling);
 181   while (1)
 182     {
 183       /* We are canceled now.  When canceled by another thread this flag
 184          is already set but if the signal is directly send (internally or
 185          from another process) is has to be done here.  */
 186       int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
 187
 188       if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
 189         /* Already canceled or exiting.  */
 190         break;
 191
 192       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
 193                                               oldval);
 194       if (curval == oldval)
 195         {
 196           /* Set the return value.  */
 197           THREAD_SETMEM (self, result, PTHREAD_CANCELED);
 198
 199           /* Make sure asynchronous cancellation is still enabled.  */
 200           if ((newval & CANCELTYPE_BITMASK) != 0)
 201             /* Run the registered destructors and terminate the thread.  */
 202             __do_cancel ();
 203
 204           break;
 205         }
 206
 207       oldval = curval;
 208     }
 209 }
 210
 211
 212 struct xid_command *__xidcmd attribute_hidden;
 213
 214 /* For asynchronous cancellation we use a signal.  This is the handler.  */
 215 static void
 216 sighandler_setxid (int sig, siginfo_t *si, void *ctx)
 217 {
 218 #ifdef __ASSUME_CORRECT_SI_PID
 219   /* Determine the process ID.  It might be negative if the thread is
 220      in the middle of a fork() call.  */
 221   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
 222   if (__builtin_expect (pid < 0, 0))
 223     pid = -pid;
 224 #endif
 225
 226   /* Safety check.  It would be possible to call this function for
 227      other signals and send a signal from another process.  This is not
 228      correct and might even be a security problem.  Try to catch as
 229      many incorrect invocations as possible.  */
 230   if (sig != SIGSETXID
 231 #ifdef __ASSUME_CORRECT_SI_PID
 232       /* Kernels before 2.5.75 stored the thread ID and not the process
 233          ID in si_pid so we skip this test.  */
 234       || si->si_pid != pid
 235 #endif
 236       || si->si_code != SI_TKILL)
 237     return;
 238
 239   INTERNAL_SYSCALL_DECL (err);
 240   INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
 241                         __xidcmd->id[1], __xidcmd->id[2]);
 242
 243   if (atomic_decrement_val (&__xidcmd->cntr) == 0)
 244     lll_futex_wake (&__xidcmd->cntr, 1, LLL_PRIVATE);
 245
 246   /* Reset the SETXID flag.  */
 247   struct pthread *self = THREAD_SELF;
 248   int flags = THREAD_GETMEM (self, cancelhandling);
 249   THREAD_SETMEM (self, cancelhandling, flags & ~SETXID_BITMASK);
 250
 251   /* And release the futex.  */
 252   self->setxid_futex = 1;
 253   lll_futex_wake (&self->setxid_futex, 1, LLL_PRIVATE);
 254 }
 255
 256
 257 /* When using __thread for this, we do it in libc so as not
 258    to give libpthread its own TLS segment just for this.  */
 259 extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
 260
 261
 262 /* This can be set by the debugger before initialization is complete.  */
 263 static bool __nptl_initial_report_events;
 264
 265 void
 266 __pthread_initialize_minimal_internal (void)
 267 {
 268 #ifndef SHARED
 269   /* Unlike in the dynamically linked case the dynamic linker has not
 270      taken care of initializing the TLS data structures.  */
 271   __libc_setup_tls (TLS_TCB_SIZE, TLS_TCB_ALIGN);
 272
 273   /* We must prevent gcc from being clever and move any of the
 274      following code ahead of the __libc_setup_tls call.  This function
 275      will initialize the thread register which is subsequently
 276      used.  */
 277   __asm __volatile ("");
 278 #endif
 279
 280   /* Minimal initialization of the thread descriptor.  */
 281   struct pthread *pd = THREAD_SELF;
 282   INTERNAL_SYSCALL_DECL (err);
 283   pd->pid = pd->tid = INTERNAL_SYSCALL (set_tid_address, err, 1, &pd->tid);
 284   THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
 285   THREAD_SETMEM (pd, user_stack, true);
 286   if (LLL_LOCK_INITIALIZER != 0)
 287     THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
 288 #if HP_TIMING_AVAIL
 289   THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
 290 #endif
 291
 292   /* Initialize the robust mutex data.  */
 293 #ifdef __PTHREAD_MUTEX_HAVE_PREV
 294   pd->robust_prev = &pd->robust_head;
 295 #endif
 296   pd->robust_head.list = &pd->robust_head;
 297 #ifdef __NR_set_robust_list
 298   pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
 299                                   - offsetof (pthread_mutex_t,
 300                                               __data.__list.__next));
 301   int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
 302                               sizeof (struct robust_list_head));
 303   if (INTERNAL_SYSCALL_ERROR_P (res, err))
 304 #endif
 305     set_robust_list_not_avail ();
 306
 307 #ifndef __ASSUME_PRIVATE_FUTEX
 308   /* Private futexes are always used (at least internally) so that
 309      doing the test once this early is beneficial.  */
 310   {
 311     int word = 0;
 312     word = INTERNAL_SYSCALL (futex, err, 3, &word,
 313                             FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1);
 314     if (!INTERNAL_SYSCALL_ERROR_P (word, err))
 315       THREAD_SETMEM (pd, header.private_futex, FUTEX_PRIVATE_FLAG);
 316   }
 317
 318   /* Private futexes have been introduced earlier than the
 319      FUTEX_CLOCK_REALTIME flag.  We don't have to run the test if we
 320      know the former are not supported.  This also means we know the
 321      kernel will return ENOSYS for unknown operations.  */
 322   if (THREAD_GETMEM (pd, header.private_futex) != 0)
 323 #endif
 324 #ifndef __ASSUME_FUTEX_CLOCK_REALTIME
 325     {
 326       int word = 0;
 327       /* NB: the syscall actually takes six parameters.  The last is the
 328          bit mask.  But since we will not actually wait at all the value
 329          is irrelevant.  Given that passing six parameters is difficult
 330          on some architectures we just pass whatever random value the
 331          calling convention calls for to the kernel.  It causes no harm.  */
 332       word = INTERNAL_SYSCALL (futex, err, 5, &word,
 333                                FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME
 334                                | FUTEX_PRIVATE_FLAG, 1, NULL, 0);
 335       assert (INTERNAL_SYSCALL_ERROR_P (word, err));
 336       if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS)
 337         __set_futex_clock_realtime ();
 338     }
 339 #endif
 340
 341   /* Set initial thread's stack block from 0 up to __libc_stack_end.
 342      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
 343      purposes this is good enough.  */
 344   THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
 345
 346   /* Initialize the list of all running threads with the main thread.  */
 347   INIT_LIST_HEAD (&__stack_user);
 348   list_add (&pd->list, &__stack_user);
 349
 350   /* Before initializing __stack_user, the debugger could not find us and
 351      had to set __nptl_initial_report_events.  Propagate its setting.  */
 352   THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
 353
 354   /* Install the cancellation signal handler.  If for some reason we
 355      cannot install the handler we do not abort.  Maybe we should, but
 356      it is only asynchronous cancellation which is affected.  */
 357   struct sigaction sa;
 358   sa.sa_sigaction = sigcancel_handler;
 359   sa.sa_flags = SA_SIGINFO;
 360   __sigemptyset (&sa.sa_mask);
 361
 362   (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
 363
 364   /* Install the handle to change the threads' uid/gid.  */
 365   sa.sa_sigaction = sighandler_setxid;
 366   sa.sa_flags = SA_SIGINFO | SA_RESTART;
 367
 368   (void) __libc_sigaction (SIGSETXID, &sa, NULL);
 369
 370   /* The parent process might have left the signals blocked.  Just in
 371      case, unblock it.  We reuse the signal mask in the sigaction
 372      structure.  It is already cleared.  */
 373   __sigaddset (&sa.sa_mask, SIGCANCEL);
 374   __sigaddset (&sa.sa_mask, SIGSETXID);
 375   (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
 376                            NULL, _NSIG / 8);
 377
 378   /* Get the size of the static and alignment requirements for the TLS
 379      block.  */
 380   size_t static_tls_align;
 381   _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
 382
 383   /* Make sure the size takes all the alignments into account.  */
 384   if (STACK_ALIGN > static_tls_align)
 385     static_tls_align = STACK_ALIGN;
 386   __static_tls_align_m1 = static_tls_align - 1;
 387
 388   __static_tls_size = roundup (__static_tls_size, static_tls_align);
 389
 390   /* Determine the default allowed stack size.  This is the size used
 391      in case the user does not specify one.  */
 392   struct rlimit limit;
 393   if (getrlimit (RLIMIT_STACK, &limit) != 0
 394       || limit.rlim_cur == RLIM_INFINITY)
 395     /* The system limit is not usable.  Use an architecture-specific
 396        default.  */
 397     limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
 398   else if (limit.rlim_cur < PTHREAD_STACK_MIN)
 399     /* The system limit is unusably small.
 400        Use the minimal size acceptable.  */
 401     limit.rlim_cur = PTHREAD_STACK_MIN;
 402
 403   /* Make sure it meets the minimum size that allocate_stack
 404      (allocatestack.c) will demand, which depends on the page size.  */
 405   const uintptr_t pagesz = __sysconf (_SC_PAGESIZE);
 406   const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
 407   if (limit.rlim_cur < minstack)
 408     limit.rlim_cur = minstack;
 409
 410   /* Round the resource limit up to page size.  */
 411   limit.rlim_cur = (limit.rlim_cur + pagesz - 1) & -pagesz;
 412   __default_stacksize = limit.rlim_cur;
 413
 414 #ifdef SHARED
 415   /* Transfer the old value from the dynamic linker's internal location.  */
 416   *__libc_dl_error_tsd () = *(*GL(dl_error_catch_tsd)) ();
 417   GL(dl_error_catch_tsd) = &__libc_dl_error_tsd;
 418
 419   /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock,
 420      keep the lock count from the ld.so implementation.  */
 421   GL(dl_rtld_lock_recursive) = (void *) INTUSE (__pthread_mutex_lock);
 422   GL(dl_rtld_unlock_recursive) = (void *) INTUSE (__pthread_mutex_unlock);
 423   unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count;
 424   GL(dl_load_lock).mutex.__data.__count = 0;
 425   while (rtld_lock_count-- > 0)
 426     INTUSE (__pthread_mutex_lock) (&GL(dl_load_lock).mutex);
 427
 428   GL(dl_make_stack_executable_hook) = &__make_stacks_executable;
 429 #endif
 430
 431   GL(dl_init_static_tls) = &__pthread_init_static_tls;
 432
 433   GL(dl_wait_lookup_done) = &__wait_lookup_done;
 434
 435   /* Register the fork generation counter with the libc.  */
 436 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
 437   __libc_multiple_threads_ptr =
 438 #endif
 439     __libc_pthread_init (&__fork_generation, __reclaim_stacks,
 440                          ptr_pthread_functions);
 441
 442   /* Determine whether the machine is SMP or not.  */
 443   __is_smp = is_smp_system ();
 444 }
 445 strong_alias (__pthread_initialize_minimal_internal,
 446               __pthread_initialize_minimal)