nptl/nptl-init.c

   1 /* Copyright (C) 2002-2018 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_setcancelstate = __pthread_setcancelstate,
 126     .ptr_pthread_setcanceltype = __pthread_setcanceltype,
 127     .ptr___pthread_cleanup_upto = __pthread_cleanup_upto,
 128     .ptr___pthread_once = __pthread_once,
 129     .ptr___pthread_rwlock_rdlock = __pthread_rwlock_rdlock,
 130     .ptr___pthread_rwlock_wrlock = __pthread_rwlock_wrlock,
 131     .ptr___pthread_rwlock_unlock = __pthread_rwlock_unlock,
 132     .ptr___pthread_key_create = __pthread_key_create,
 133     .ptr___pthread_getspecific = __pthread_getspecific,
 134     .ptr___pthread_setspecific = __pthread_setspecific,
 135     .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer,
 136     .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore,
 137     .ptr_nthreads = &__nptl_nthreads,
 138     .ptr___pthread_unwind = &__pthread_unwind,
 139     .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd,
 140 # ifdef SIGSETXID
 141     .ptr__nptl_setxid = __nptl_setxid,
 142 # endif
 143     /* For now only the stack cache needs to be freed.  */
 144     .ptr_freeres = nptl_freeres,
 145     .ptr_set_robust = __nptl_set_robust
 146   };
 147 # define ptr_pthread_functions &pthread_functions
 148 #else
 149 # define ptr_pthread_functions NULL
 150 #endif
 151
 152
 153 #ifdef SHARED
 154 /* This function is called indirectly from the freeres code in libc.  */
 155 static void
 156 __libc_freeres_fn_section
 157 nptl_freeres (void)
 158 {
 159   __unwind_freeres ();
 160   __free_stacks (0);
 161 }
 162
 163
 164 static
 165 #endif
 166 void
 167 __nptl_set_robust (struct pthread *self)
 168 {
 169 #ifdef __NR_set_robust_list
 170   INTERNAL_SYSCALL_DECL (err);
 171   INTERNAL_SYSCALL (set_robust_list, err, 2, &self->robust_head,
 172                     sizeof (struct robust_list_head));
 173 #endif
 174 }
 175
 176
 177 #ifdef SIGCANCEL
 178 /* For asynchronous cancellation we use a signal.  This is the handler.  */
 179 static void
 180 sigcancel_handler (int sig, siginfo_t *si, void *ctx)
 181 {
 182   /* Safety check.  It would be possible to call this function for
 183      other signals and send a signal from another process.  This is not
 184      correct and might even be a security problem.  Try to catch as
 185      many incorrect invocations as possible.  */
 186   if (sig != SIGCANCEL
 187       || si->si_pid != __getpid()
 188       || si->si_code != SI_TKILL)
 189     return;
 190
 191   struct pthread *self = THREAD_SELF;
 192
 193   int oldval = THREAD_GETMEM (self, cancelhandling);
 194   while (1)
 195     {
 196       /* We are canceled now.  When canceled by another thread this flag
 197          is already set but if the signal is directly send (internally or
 198          from another process) is has to be done here.  */
 199       int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
 200
 201       if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
 202         /* Already canceled or exiting.  */
 203         break;
 204
 205       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
 206                                               oldval);
 207       if (curval == oldval)
 208         {
 209           /* Set the return value.  */
 210           THREAD_SETMEM (self, result, PTHREAD_CANCELED);
 211
 212           /* Make sure asynchronous cancellation is still enabled.  */
 213           if ((newval & CANCELTYPE_BITMASK) != 0)
 214             /* Run the registered destructors and terminate the thread.  */
 215             __do_cancel ();
 216
 217           break;
 218         }
 219
 220       oldval = curval;
 221     }
 222 }
 223 #endif
 224
 225
 226 #ifdef SIGSETXID
 227 struct xid_command *__xidcmd attribute_hidden;
 228
 229 /* We use the SIGSETXID signal in the setuid, setgid, etc. implementations to
 230    tell each thread to call the respective setxid syscall on itself.  This is
 231    the handler.  */
 232 static void
 233 sighandler_setxid (int sig, siginfo_t *si, void *ctx)
 234 {
 235   int result;
 236
 237   /* Safety check.  It would be possible to call this function for
 238      other signals and send a signal from another process.  This is not
 239      correct and might even be a security problem.  Try to catch as
 240      many incorrect invocations as possible.  */
 241   if (sig != SIGSETXID
 242       || si->si_pid != __getpid ()
 243       || si->si_code != SI_TKILL)
 244     return;
 245
 246   INTERNAL_SYSCALL_DECL (err);
 247   result = INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
 248                                  __xidcmd->id[1], __xidcmd->id[2]);
 249   int error = 0;
 250   if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
 251     error = INTERNAL_SYSCALL_ERRNO (result, err);
 252   __nptl_setxid_error (__xidcmd, error);
 253
 254   /* Reset the SETXID flag.  */
 255   struct pthread *self = THREAD_SELF;
 256   int flags, newval;
 257   do
 258     {
 259       flags = THREAD_GETMEM (self, cancelhandling);
 260       newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
 261                                           flags & ~SETXID_BITMASK, flags);
 262     }
 263   while (flags != newval);
 264
 265   /* And release the futex.  */
 266   self->setxid_futex = 1;
 267   futex_wake (&self->setxid_futex, 1, FUTEX_PRIVATE);
 268
 269   if (atomic_decrement_val (&__xidcmd->cntr) == 0)
 270     futex_wake ((unsigned int *) &__xidcmd->cntr, 1, FUTEX_PRIVATE);
 271 }
 272 #endif
 273
 274
 275 /* When using __thread for this, we do it in libc so as not
 276    to give libpthread its own TLS segment just for this.  */
 277 extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
 278
 279
 280 /* This can be set by the debugger before initialization is complete.  */
 281 static bool __nptl_initial_report_events __attribute_used__;
 282
 283 void
 284 __pthread_initialize_minimal_internal (void)
 285 {
 286   /* Minimal initialization of the thread descriptor.  */
 287   struct pthread *pd = THREAD_SELF;
 288   __pthread_initialize_pids (pd);
 289   THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
 290   THREAD_SETMEM (pd, user_stack, true);
 291   if (LLL_LOCK_INITIALIZER != 0)
 292     THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
 293 #if HP_TIMING_AVAIL
 294   THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
 295 #endif
 296
 297   /* Initialize the robust mutex data.  */
 298   {
 299 #if __PTHREAD_MUTEX_HAVE_PREV
 300     pd->robust_prev = &pd->robust_head;
 301 #endif
 302     pd->robust_head.list = &pd->robust_head;
 303 #ifdef __NR_set_robust_list
 304     pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
 305                                     - offsetof (pthread_mutex_t,
 306                                                 __data.__list.__next));
 307     INTERNAL_SYSCALL_DECL (err);
 308     int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
 309                                 sizeof (struct robust_list_head));
 310     if (INTERNAL_SYSCALL_ERROR_P (res, err))
 311 #endif
 312       set_robust_list_not_avail ();
 313   }
 314
 315 #ifdef __NR_futex
 316 # ifndef __ASSUME_PRIVATE_FUTEX
 317   /* Private futexes are always used (at least internally) so that
 318      doing the test once this early is beneficial.  */
 319   {
 320     int word = 0;
 321     INTERNAL_SYSCALL_DECL (err);
 322     word = INTERNAL_SYSCALL (futex, err, 3, &word,
 323                             FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1);
 324     if (!INTERNAL_SYSCALL_ERROR_P (word, err))
 325       THREAD_SETMEM (pd, header.private_futex, FUTEX_PRIVATE_FLAG);
 326   }
 327
 328   /* Private futexes have been introduced earlier than the
 329      FUTEX_CLOCK_REALTIME flag.  We don't have to run the test if we
 330      know the former are not supported.  This also means we know the
 331      kernel will return ENOSYS for unknown operations.  */
 332   if (THREAD_GETMEM (pd, header.private_futex) != 0)
 333 # endif
 334 # ifndef __ASSUME_FUTEX_CLOCK_REALTIME
 335     {
 336       int word = 0;
 337       /* NB: the syscall actually takes six parameters.  The last is the
 338          bit mask.  But since we will not actually wait at all the value
 339          is irrelevant.  Given that passing six parameters is difficult
 340          on some architectures we just pass whatever random value the
 341          calling convention calls for to the kernel.  It causes no harm.  */
 342       INTERNAL_SYSCALL_DECL (err);
 343       word = INTERNAL_SYSCALL (futex, err, 5, &word,
 344                                FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME
 345                                | FUTEX_PRIVATE_FLAG, 1, NULL, 0);
 346       assert (INTERNAL_SYSCALL_ERROR_P (word, err));
 347       if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS)
 348         __set_futex_clock_realtime ();
 349     }
 350 # endif
 351 #endif
 352
 353   /* Set initial thread's stack block from 0 up to __libc_stack_end.
 354      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
 355      purposes this is good enough.  */
 356   THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
 357
 358   /* Initialize the list of all running threads with the main thread.  */
 359   INIT_LIST_HEAD (&__stack_user);
 360   list_add (&pd->list, &__stack_user);
 361
 362   /* Before initializing __stack_user, the debugger could not find us and
 363      had to set __nptl_initial_report_events.  Propagate its setting.  */
 364   THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
 365
 366 #if defined SIGCANCEL || defined SIGSETXID
 367   struct sigaction sa;
 368   __sigemptyset (&sa.sa_mask);
 369
 370 # ifdef SIGCANCEL
 371   /* Install the cancellation signal handler.  If for some reason we
 372      cannot install the handler we do not abort.  Maybe we should, but
 373      it is only asynchronous cancellation which is affected.  */
 374   sa.sa_sigaction = sigcancel_handler;
 375   sa.sa_flags = SA_SIGINFO;
 376   (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
 377 # endif
 378
 379 # ifdef SIGSETXID
 380   /* Install the handle to change the threads' uid/gid.  */
 381   sa.sa_sigaction = sighandler_setxid;
 382   sa.sa_flags = SA_SIGINFO | SA_RESTART;
 383   (void) __libc_sigaction (SIGSETXID, &sa, NULL);
 384 # endif
 385
 386   /* The parent process might have left the signals blocked.  Just in
 387      case, unblock it.  We reuse the signal mask in the sigaction
 388      structure.  It is already cleared.  */
 389 # ifdef SIGCANCEL
 390   __sigaddset (&sa.sa_mask, SIGCANCEL);
 391 # endif
 392 # ifdef SIGSETXID
 393   __sigaddset (&sa.sa_mask, SIGSETXID);
 394 # endif
 395   {
 396     INTERNAL_SYSCALL_DECL (err);
 397     (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
 398                              NULL, _NSIG / 8);
 399   }
 400 #endif
 401
 402   /* Get the size of the static and alignment requirements for the TLS
 403      block.  */
 404   size_t static_tls_align;
 405   _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
 406
 407   /* Make sure the size takes all the alignments into account.  */
 408   if (STACK_ALIGN > static_tls_align)
 409     static_tls_align = STACK_ALIGN;
 410   __static_tls_align_m1 = static_tls_align - 1;
 411
 412   __static_tls_size = roundup (__static_tls_size, static_tls_align);
 413
 414   /* Determine the default allowed stack size.  This is the size used
 415      in case the user does not specify one.  */
 416   struct rlimit limit;
 417   if (__getrlimit (RLIMIT_STACK, &limit) != 0
 418       || limit.rlim_cur == RLIM_INFINITY)
 419     /* The system limit is not usable.  Use an architecture-specific
 420        default.  */
 421     limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
 422   else if (limit.rlim_cur < PTHREAD_STACK_MIN)
 423     /* The system limit is unusably small.
 424        Use the minimal size acceptable.  */
 425     limit.rlim_cur = PTHREAD_STACK_MIN;
 426
 427   /* Make sure it meets the minimum size that allocate_stack
 428      (allocatestack.c) will demand, which depends on the page size.  */
 429   const uintptr_t pagesz = GLRO(dl_pagesize);
 430   const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
 431   if (limit.rlim_cur < minstack)
 432     limit.rlim_cur = minstack;
 433
 434   /* Round the resource limit up to page size.  */
 435   limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz);
 436   lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
 437   __default_pthread_attr.stacksize = limit.rlim_cur;
 438   __default_pthread_attr.guardsize = GLRO (dl_pagesize);
 439   lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
 440
 441 #ifdef SHARED
 442   /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock,
 443      keep the lock count from the ld.so implementation.  */
 444   GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock;
 445   GL(dl_rtld_unlock_recursive) = (void *) __pthread_mutex_unlock;
 446   unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count;
 447   GL(dl_load_lock).mutex.__data.__count = 0;
 448   while (rtld_lock_count-- > 0)
 449     __pthread_mutex_lock (&GL(dl_load_lock).mutex);
 450
 451   GL(dl_make_stack_executable_hook) = &__make_stacks_executable;
 452 #endif
 453
 454   GL(dl_init_static_tls) = &__pthread_init_static_tls;
 455
 456   GL(dl_wait_lookup_done) = &__wait_lookup_done;
 457
 458   /* Register the fork generation counter with the libc.  */
 459 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
 460   __libc_multiple_threads_ptr =
 461 #endif
 462     __libc_pthread_init (&__fork_generation, __reclaim_stacks,
 463                          ptr_pthread_functions);
 464
 465   /* Determine whether the machine is SMP or not.  */
 466   __is_smp = is_smp_system ();
 467 }
 468 strong_alias (__pthread_initialize_minimal_internal,
 469               __pthread_initialize_minimal)
 470
 471
 472 size_t
 473 __pthread_get_minstack (const pthread_attr_t *attr)
 474 {
 475   return GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN;
 476 }