nptl/nptl-init.c

   1 /* Copyright (C) 2002-2019 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    <https://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 #include <pthread_mutex_conf.h>
  42
  43 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
  44 /* Pointer to the corresponding variable in libc.  */
  45 int *__libc_multiple_threads_ptr attribute_hidden;
  46 #endif
  47
  48 /* Size and alignment of static TLS block.  */
  49 size_t __static_tls_size;
  50 size_t __static_tls_align_m1;
  51
  52 #ifndef __ASSUME_SET_ROBUST_LIST
  53 /* Negative if we do not have the system call and we can use it.  */
  54 int __set_robust_list_avail;
  55 # define set_robust_list_not_avail() \
  56   __set_robust_list_avail = -1
  57 #else
  58 # define set_robust_list_not_avail() do { } while (0)
  59 #endif
  60
  61 /* Version of the library, used in libthread_db to detect mismatches.  */
  62 static const char nptl_version[] __attribute_used__ = VERSION;
  63
  64
  65 #ifdef SHARED
  66 static
  67 #else
  68 extern
  69 #endif
  70 void __nptl_set_robust (struct pthread *);
  71
  72 #ifdef SHARED
  73 static const struct pthread_functions pthread_functions =
  74   {
  75     .ptr_pthread_attr_setinheritsched = __pthread_attr_setinheritsched,
  76     .ptr_pthread_attr_getschedparam = __pthread_attr_getschedparam,
  77     .ptr_pthread_attr_setschedparam = __pthread_attr_setschedparam,
  78     .ptr_pthread_attr_getschedpolicy = __pthread_attr_getschedpolicy,
  79     .ptr_pthread_attr_setschedpolicy = __pthread_attr_setschedpolicy,
  80     .ptr_pthread_attr_getscope = __pthread_attr_getscope,
  81     .ptr_pthread_attr_setscope = __pthread_attr_setscope,
  82     .ptr_pthread_condattr_destroy = __pthread_condattr_destroy,
  83     .ptr_pthread_condattr_init = __pthread_condattr_init,
  84     .ptr___pthread_cond_broadcast = __pthread_cond_broadcast,
  85     .ptr___pthread_cond_destroy = __pthread_cond_destroy,
  86     .ptr___pthread_cond_init = __pthread_cond_init,
  87     .ptr___pthread_cond_signal = __pthread_cond_signal,
  88     .ptr___pthread_cond_wait = __pthread_cond_wait,
  89     .ptr___pthread_cond_timedwait = __pthread_cond_timedwait,
  90 # if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_3_2)
  91     .ptr___pthread_cond_broadcast_2_0 = __pthread_cond_broadcast_2_0,
  92     .ptr___pthread_cond_destroy_2_0 = __pthread_cond_destroy_2_0,
  93     .ptr___pthread_cond_init_2_0 = __pthread_cond_init_2_0,
  94     .ptr___pthread_cond_signal_2_0 = __pthread_cond_signal_2_0,
  95     .ptr___pthread_cond_wait_2_0 = __pthread_cond_wait_2_0,
  96     .ptr___pthread_cond_timedwait_2_0 = __pthread_cond_timedwait_2_0,
  97 # endif
  98     .ptr___pthread_exit = __pthread_exit,
  99     .ptr_pthread_getschedparam = __pthread_getschedparam,
 100     .ptr_pthread_setschedparam = __pthread_setschedparam,
 101     .ptr_pthread_mutex_destroy = __pthread_mutex_destroy,
 102     .ptr_pthread_mutex_init = __pthread_mutex_init,
 103     .ptr_pthread_mutex_lock = __pthread_mutex_lock,
 104     .ptr_pthread_mutex_unlock = __pthread_mutex_unlock,
 105     .ptr___pthread_setcancelstate = __pthread_setcancelstate,
 106     .ptr_pthread_setcanceltype = __pthread_setcanceltype,
 107     .ptr___pthread_cleanup_upto = __pthread_cleanup_upto,
 108     .ptr___pthread_once = __pthread_once,
 109     .ptr___pthread_rwlock_rdlock = __pthread_rwlock_rdlock,
 110     .ptr___pthread_rwlock_wrlock = __pthread_rwlock_wrlock,
 111     .ptr___pthread_rwlock_unlock = __pthread_rwlock_unlock,
 112     .ptr___pthread_key_create = __pthread_key_create,
 113     .ptr___pthread_getspecific = __pthread_getspecific,
 114     .ptr___pthread_setspecific = __pthread_setspecific,
 115     .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer,
 116     .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore,
 117     .ptr_nthreads = &__nptl_nthreads,
 118     .ptr___pthread_unwind = &__pthread_unwind,
 119     .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd,
 120 # ifdef SIGSETXID
 121     .ptr__nptl_setxid = __nptl_setxid,
 122 # endif
 123     .ptr_set_robust = __nptl_set_robust
 124   };
 125 # define ptr_pthread_functions &pthread_functions
 126 #else
 127 # define ptr_pthread_functions NULL
 128 #endif
 129
 130
 131 #ifdef SHARED
 132 static
 133 #endif
 134 void
 135 __nptl_set_robust (struct pthread *self)
 136 {
 137 #ifdef __NR_set_robust_list
 138   INTERNAL_SYSCALL_DECL (err);
 139   INTERNAL_SYSCALL (set_robust_list, err, 2, &self->robust_head,
 140                     sizeof (struct robust_list_head));
 141 #endif
 142 }
 143
 144
 145 #ifdef SIGCANCEL
 146 /* For asynchronous cancellation we use a signal.  This is the handler.  */
 147 static void
 148 sigcancel_handler (int sig, siginfo_t *si, void *ctx)
 149 {
 150   /* Safety check.  It would be possible to call this function for
 151      other signals and send a signal from another process.  This is not
 152      correct and might even be a security problem.  Try to catch as
 153      many incorrect invocations as possible.  */
 154   if (sig != SIGCANCEL
 155       || si->si_pid != __getpid()
 156       || si->si_code != SI_TKILL)
 157     return;
 158
 159   struct pthread *self = THREAD_SELF;
 160
 161   int oldval = THREAD_GETMEM (self, cancelhandling);
 162   while (1)
 163     {
 164       /* We are canceled now.  When canceled by another thread this flag
 165          is already set but if the signal is directly send (internally or
 166          from another process) is has to be done here.  */
 167       int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
 168
 169       if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
 170         /* Already canceled or exiting.  */
 171         break;
 172
 173       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
 174                                               oldval);
 175       if (curval == oldval)
 176         {
 177           /* Set the return value.  */
 178           THREAD_SETMEM (self, result, PTHREAD_CANCELED);
 179
 180           /* Make sure asynchronous cancellation is still enabled.  */
 181           if ((newval & CANCELTYPE_BITMASK) != 0)
 182             /* Run the registered destructors and terminate the thread.  */
 183             __do_cancel ();
 184
 185           break;
 186         }
 187
 188       oldval = curval;
 189     }
 190 }
 191 #endif
 192
 193
 194 #ifdef SIGSETXID
 195 struct xid_command *__xidcmd attribute_hidden;
 196
 197 /* We use the SIGSETXID signal in the setuid, setgid, etc. implementations to
 198    tell each thread to call the respective setxid syscall on itself.  This is
 199    the handler.  */
 200 static void
 201 sighandler_setxid (int sig, siginfo_t *si, void *ctx)
 202 {
 203   int result;
 204
 205   /* Safety check.  It would be possible to call this function for
 206      other signals and send a signal from another process.  This is not
 207      correct and might even be a security problem.  Try to catch as
 208      many incorrect invocations as possible.  */
 209   if (sig != SIGSETXID
 210       || si->si_pid != __getpid ()
 211       || si->si_code != SI_TKILL)
 212     return;
 213
 214   INTERNAL_SYSCALL_DECL (err);
 215   result = INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
 216                                  __xidcmd->id[1], __xidcmd->id[2]);
 217   int error = 0;
 218   if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
 219     error = INTERNAL_SYSCALL_ERRNO (result, err);
 220   __nptl_setxid_error (__xidcmd, error);
 221
 222   /* Reset the SETXID flag.  */
 223   struct pthread *self = THREAD_SELF;
 224   int flags, newval;
 225   do
 226     {
 227       flags = THREAD_GETMEM (self, cancelhandling);
 228       newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
 229                                           flags & ~SETXID_BITMASK, flags);
 230     }
 231   while (flags != newval);
 232
 233   /* And release the futex.  */
 234   self->setxid_futex = 1;
 235   futex_wake (&self->setxid_futex, 1, FUTEX_PRIVATE);
 236
 237   if (atomic_decrement_val (&__xidcmd->cntr) == 0)
 238     futex_wake ((unsigned int *) &__xidcmd->cntr, 1, FUTEX_PRIVATE);
 239 }
 240 #endif
 241
 242
 243 /* When using __thread for this, we do it in libc so as not
 244    to give libpthread its own TLS segment just for this.  */
 245 extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
 246
 247
 248 /* This can be set by the debugger before initialization is complete.  */
 249 static bool __nptl_initial_report_events __attribute_used__;
 250
 251 void
 252 __pthread_initialize_minimal_internal (void)
 253 {
 254   /* Minimal initialization of the thread descriptor.  */
 255   struct pthread *pd = THREAD_SELF;
 256   __pthread_initialize_pids (pd);
 257   THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
 258   THREAD_SETMEM (pd, user_stack, true);
 259
 260   /* Initialize the robust mutex data.  */
 261   {
 262 #if __PTHREAD_MUTEX_HAVE_PREV
 263     pd->robust_prev = &pd->robust_head;
 264 #endif
 265     pd->robust_head.list = &pd->robust_head;
 266 #ifdef __NR_set_robust_list
 267     pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
 268                                     - offsetof (pthread_mutex_t,
 269                                                 __data.__list.__next));
 270     INTERNAL_SYSCALL_DECL (err);
 271     int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
 272                                 sizeof (struct robust_list_head));
 273     if (INTERNAL_SYSCALL_ERROR_P (res, err))
 274 #endif
 275       set_robust_list_not_avail ();
 276   }
 277
 278   /* Set initial thread's stack block from 0 up to __libc_stack_end.
 279      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
 280      purposes this is good enough.  */
 281   THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
 282
 283   /* Initialize the list of all running threads with the main thread.  */
 284   INIT_LIST_HEAD (&__stack_user);
 285   list_add (&pd->list, &__stack_user);
 286
 287   /* Before initializing __stack_user, the debugger could not find us and
 288      had to set __nptl_initial_report_events.  Propagate its setting.  */
 289   THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
 290
 291 #if defined SIGCANCEL || defined SIGSETXID
 292   struct sigaction sa;
 293   __sigemptyset (&sa.sa_mask);
 294
 295 # ifdef SIGCANCEL
 296   /* Install the cancellation signal handler.  If for some reason we
 297      cannot install the handler we do not abort.  Maybe we should, but
 298      it is only asynchronous cancellation which is affected.  */
 299   sa.sa_sigaction = sigcancel_handler;
 300   sa.sa_flags = SA_SIGINFO;
 301   (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
 302 # endif
 303
 304 # ifdef SIGSETXID
 305   /* Install the handle to change the threads' uid/gid.  */
 306   sa.sa_sigaction = sighandler_setxid;
 307   sa.sa_flags = SA_SIGINFO | SA_RESTART;
 308   (void) __libc_sigaction (SIGSETXID, &sa, NULL);
 309 # endif
 310
 311   /* The parent process might have left the signals blocked.  Just in
 312      case, unblock it.  We reuse the signal mask in the sigaction
 313      structure.  It is already cleared.  */
 314 # ifdef SIGCANCEL
 315   __sigaddset (&sa.sa_mask, SIGCANCEL);
 316 # endif
 317 # ifdef SIGSETXID
 318   __sigaddset (&sa.sa_mask, SIGSETXID);
 319 # endif
 320   {
 321     INTERNAL_SYSCALL_DECL (err);
 322     (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
 323                              NULL, _NSIG / 8);
 324   }
 325 #endif
 326
 327   /* Get the size of the static and alignment requirements for the TLS
 328      block.  */
 329   size_t static_tls_align;
 330   _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
 331
 332   /* Make sure the size takes all the alignments into account.  */
 333   if (STACK_ALIGN > static_tls_align)
 334     static_tls_align = STACK_ALIGN;
 335   __static_tls_align_m1 = static_tls_align - 1;
 336
 337   __static_tls_size = roundup (__static_tls_size, static_tls_align);
 338
 339   /* Determine the default allowed stack size.  This is the size used
 340      in case the user does not specify one.  */
 341   struct rlimit limit;
 342   if (__getrlimit (RLIMIT_STACK, &limit) != 0
 343       || limit.rlim_cur == RLIM_INFINITY)
 344     /* The system limit is not usable.  Use an architecture-specific
 345        default.  */
 346     limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
 347   else if (limit.rlim_cur < PTHREAD_STACK_MIN)
 348     /* The system limit is unusably small.
 349        Use the minimal size acceptable.  */
 350     limit.rlim_cur = PTHREAD_STACK_MIN;
 351
 352   /* Make sure it meets the minimum size that allocate_stack
 353      (allocatestack.c) will demand, which depends on the page size.  */
 354   const uintptr_t pagesz = GLRO(dl_pagesize);
 355   const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
 356   if (limit.rlim_cur < minstack)
 357     limit.rlim_cur = minstack;
 358
 359   /* Round the resource limit up to page size.  */
 360   limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz);
 361   lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
 362   __default_pthread_attr.stacksize = limit.rlim_cur;
 363   __default_pthread_attr.guardsize = GLRO (dl_pagesize);
 364   lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
 365
 366 #ifdef SHARED
 367   /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock,
 368      keep the lock count from the ld.so implementation.  */
 369   GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock;
 370   GL(dl_rtld_unlock_recursive) = (void *) __pthread_mutex_unlock;
 371   unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count;
 372   GL(dl_load_lock).mutex.__data.__count = 0;
 373   while (rtld_lock_count-- > 0)
 374     __pthread_mutex_lock (&GL(dl_load_lock).mutex);
 375
 376   GL(dl_make_stack_executable_hook) = &__make_stacks_executable;
 377 #endif
 378
 379   GL(dl_init_static_tls) = &__pthread_init_static_tls;
 380
 381   GL(dl_wait_lookup_done) = &__wait_lookup_done;
 382
 383   /* Register the fork generation counter with the libc.  */
 384 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
 385   __libc_multiple_threads_ptr =
 386 #endif
 387     __libc_pthread_init (&__fork_generation, __reclaim_stacks,
 388                          ptr_pthread_functions);
 389
 390   /* Determine whether the machine is SMP or not.  */
 391   __is_smp = is_smp_system ();
 392
 393 #if HAVE_TUNABLES
 394   __pthread_tunables_init ();
 395 #endif
 396 }
 397 strong_alias (__pthread_initialize_minimal_internal,
 398               __pthread_initialize_minimal)
 399
 400
 401 /* This function is internal (it has a GLIBC_PRIVATE) version, but it
 402    is widely used (either via weak symbol, or dlsym) to obtain the
 403    __static_tls_size value.  This value is then used to adjust the
 404    value of the stack size attribute, so that applications receive the
 405    full requested stack size, not diminished by the TCB and static TLS
 406    allocation on the stack.  Once the TCB is separately allocated,
 407    this function should be removed or renamed (if it is still
 408    necessary at that point).  */
 409 size_t
 410 __pthread_get_minstack (const pthread_attr_t *attr)
 411 {
 412   return GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN;
 413 }