libpthread/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, 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 <fork.h>
  32 #include <version.h>
  33 #include <smp.h>
  34 #include <lowlevellock.h>
  35 #include <bits/kernel-features.h>
  36 #include <stdio.h>
  37
  38 /* Size and alignment of static TLS block.  */
  39 size_t __static_tls_size;
  40 size_t __static_tls_align_m1;
  41
  42 #ifndef __ASSUME_SET_ROBUST_LIST
  43 /* Negative if we do not have the system call and we can use it.  */
  44 int __set_robust_list_avail;
  45 # define set_robust_list_not_avail() \
  46   __set_robust_list_avail = -1
  47 #else
  48 # define set_robust_list_not_avail() do { } while (0)
  49 #endif
  50
  51 #ifndef __ASSUME_FUTEX_CLOCK_REALTIME
  52 /* Nonzero if we do not have FUTEX_CLOCK_REALTIME.  */
  53 int __have_futex_clock_realtime;
  54 # define __set_futex_clock_realtime() \
  55   __have_futex_clock_realtime = 1
  56 #else
  57 #define __set_futex_clock_realtime() do { } while (0)
  58 #endif
  59
  60 /* Version of the library, used in libthread_db to detect mismatches.  */
  61 static const char nptl_version[] __attribute_used__ = VERSION;
  62
  63 /* For asynchronous cancellation we use a signal.  This is the handler.  */
  64 static void
  65 sigcancel_handler (int sig, siginfo_t *si, void *ctx)
  66 {
  67
  68   /* Safety check.  It would be possible to call this function for
  69      other signals and send a signal from another process.  This is not
  70      correct and might even be a security problem.  Try to catch as
  71      many incorrect invocations as possible.  */
  72   if (sig != SIGCANCEL
  73       || si->si_pid != getpid()
  74       || si->si_code != SI_TKILL)
  75     return;
  76
  77   struct pthread *self = THREAD_SELF;
  78
  79   int oldval = THREAD_GETMEM (self, cancelhandling);
  80   while (1)
  81     {
  82       /* We are canceled now.  When canceled by another thread this flag
  83          is already set but if the signal is directly send (internally or
  84          from another process) is has to be done here.  */
  85       int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
  86
  87       if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
  88         /* Already canceled or exiting.  */
  89         break;
  90
  91       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
  92                                               oldval);
  93       if (curval == oldval)
  94         {
  95           /* Set the return value.  */
  96           THREAD_SETMEM (self, result, PTHREAD_CANCELED);
  97
  98           /* Make sure asynchronous cancellation is still enabled.  */
  99           if ((newval & CANCELTYPE_BITMASK) != 0)
 100             /* Run the registered destructors and terminate the thread.  */
 101             __do_cancel ();
 102
 103           break;
 104         }
 105
 106       oldval = curval;
 107     }
 108 }
 109
 110
 111 struct xid_command *__xidcmd attribute_hidden;
 112
 113 /* For asynchronous cancellation we use a signal.  This is the handler.  */
 114 static void
 115 sighandler_setxid (int sig, siginfo_t *si, void *ctx)
 116 {
 117
 118   /* Safety check.  It would be possible to call this function for
 119      other signals and send a signal from another process.  This is not
 120      correct and might even be a security problem.  Try to catch as
 121      many incorrect invocations as possible.  */
 122   if (sig != SIGSETXID
 123       || si->si_pid != getpid()
 124       || si->si_code != SI_TKILL)
 125     return;
 126
 127   INTERNAL_SYSCALL_DECL (err);
 128   INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
 129                         __xidcmd->id[1], __xidcmd->id[2]);
 130
 131   /* Reset the SETXID flag.  */
 132   struct pthread *self = THREAD_SELF;
 133   int flags, newval;
 134   do
 135     {
 136       flags = THREAD_GETMEM (self, cancelhandling);
 137       newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
 138                                           flags & ~SETXID_BITMASK, flags);
 139     }
 140   while (flags != newval);
 141
 142   /* And release the futex.  */
 143   self->setxid_futex = 1;
 144   lll_futex_wake (&self->setxid_futex, 1, LLL_PRIVATE);
 145
 146   if (atomic_decrement_val (&__xidcmd->cntr) == 0)
 147     lll_futex_wake (&__xidcmd->cntr, 1, LLL_PRIVATE);
 148 }
 149
 150
 151 /* When using __thread for this, we do it in libc so as not
 152    to give libpthread its own TLS segment just for this.  */
 153 extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
 154
 155
 156 /* This can be set by the debugger before initialization is complete.  */
 157 static bool __nptl_initial_report_events __attribute_used__;
 158
 159 void __pthread_initialize_minimal_internal (void) attribute_hidden;
 160 void
 161 __pthread_initialize_minimal_internal (void)
 162 {
 163   static int initialized = 0;
 164
 165   if (initialized)
 166     return;
 167   initialized = 1;
 168
 169   /* Minimal initialization of the thread descriptor.  */
 170   struct pthread *pd = THREAD_SELF;
 171   INTERNAL_SYSCALL_DECL (err);
 172   pd->tid = INTERNAL_SYSCALL (set_tid_address, err, 1, &pd->tid);
 173   THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
 174   THREAD_SETMEM (pd, user_stack, true);
 175   if (LLL_LOCK_INITIALIZER != 0)
 176     THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
 177 #if HP_TIMING_AVAIL
 178   THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
 179 #endif
 180
 181   /* Initialize the robust mutex data.  */
 182 #ifdef __PTHREAD_MUTEX_HAVE_PREV
 183   pd->robust_prev = &pd->robust_head;
 184 #endif
 185   pd->robust_head.list = &pd->robust_head;
 186 #ifdef __NR_set_robust_list
 187   pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
 188                                   - offsetof (pthread_mutex_t,
 189                                               __data.__list.__next));
 190   int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
 191                               sizeof (struct robust_list_head));
 192   if (INTERNAL_SYSCALL_ERROR_P (res, err))
 193 #endif
 194     set_robust_list_not_avail ();
 195
 196 #ifndef __ASSUME_PRIVATE_FUTEX
 197   /* Private futexes are always used (at least internally) so that
 198      doing the test once this early is beneficial.  */
 199   {
 200     int word = 0;
 201     word = INTERNAL_SYSCALL (futex, err, 3, &word,
 202                             FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1);
 203     if (!INTERNAL_SYSCALL_ERROR_P (word, err))
 204       THREAD_SETMEM (pd, header.private_futex, FUTEX_PRIVATE_FLAG);
 205   }
 206
 207   /* Private futexes have been introduced earlier than the
 208      FUTEX_CLOCK_REALTIME flag.  We don't have to run the test if we
 209      know the former are not supported.  This also means we know the
 210      kernel will return ENOSYS for unknown operations.  */
 211   if (THREAD_GETMEM (pd, header.private_futex) != 0)
 212 #endif
 213 #ifndef __ASSUME_FUTEX_CLOCK_REALTIME
 214     {
 215       int word = 0;
 216       /* NB: the syscall actually takes six parameters.  The last is the
 217          bit mask.  But since we will not actually wait at all the value
 218          is irrelevant.  Given that passing six parameters is difficult
 219          on some architectures we just pass whatever random value the
 220          calling convention calls for to the kernel.  It causes no harm.  */
 221       word = INTERNAL_SYSCALL (futex, err, 5, &word,
 222                                FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME
 223                                | FUTEX_PRIVATE_FLAG, 1, NULL, 0);
 224       assert (INTERNAL_SYSCALL_ERROR_P (word, err));
 225       if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS)
 226         __set_futex_clock_realtime ();
 227     }
 228 #endif
 229
 230   /* Set initial thread's stack block from 0 up to __libc_stack_end.
 231      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
 232      purposes this is good enough.  */
 233   THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
 234
 235   /* Initialize the list of all running threads with the main thread.  */
 236   INIT_LIST_HEAD (&__stack_user);
 237   list_add (&pd->list, &__stack_user);
 238
 239   /* Before initializing __stack_user, the debugger could not find us and
 240      had to set __nptl_initial_report_events.  Propagate its setting.  */
 241   THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
 242
 243   /* Install the cancellation signal handler.  If for some reason we
 244      cannot install the handler we do not abort.  Maybe we should, but
 245      it is only asynchronous cancellation which is affected.  */
 246   struct sigaction sa;
 247   sa.sa_sigaction = sigcancel_handler;
 248   sa.sa_flags = SA_SIGINFO;
 249   __sigemptyset (&sa.sa_mask);
 250
 251   (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
 252
 253   /* Install the handle to change the threads' uid/gid.  */
 254   sa.sa_sigaction = sighandler_setxid;
 255   sa.sa_flags = SA_SIGINFO | SA_RESTART;
 256
 257   (void) __libc_sigaction (SIGSETXID, &sa, NULL);
 258
 259   /* The parent process might have left the signals blocked.  Just in
 260      case, unblock it.  We reuse the signal mask in the sigaction
 261      structure.  It is already cleared.  */
 262   __sigaddset (&sa.sa_mask, SIGCANCEL);
 263   __sigaddset (&sa.sa_mask, SIGSETXID);
 264   (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
 265                            NULL, _NSIG / 8);
 266
 267   /* Get the size of the static and alignment requirements for the TLS
 268      block.  */
 269   size_t static_tls_align;
 270   _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
 271
 272   /* Make sure the size takes all the alignments into account.  */
 273   if (STACK_ALIGN > static_tls_align)
 274     static_tls_align = STACK_ALIGN;
 275   __static_tls_align_m1 = static_tls_align - 1;
 276
 277   __static_tls_size = roundup (__static_tls_size, static_tls_align);
 278
 279   /* Determine the default allowed stack size.  This is the size used
 280      in case the user does not specify one.  */
 281   struct rlimit limit;
 282   if (getrlimit (RLIMIT_STACK, &limit) != 0
 283       || limit.rlim_cur == RLIM_INFINITY)
 284     /* The system limit is not usable.  Use an architecture-specific
 285        default.  */
 286     limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
 287   else if (limit.rlim_cur < PTHREAD_STACK_MIN)
 288     /* The system limit is unusably small.
 289        Use the minimal size acceptable.  */
 290     limit.rlim_cur = PTHREAD_STACK_MIN;
 291
 292   /* Do not exceed architecture specific default */
 293   if (limit.rlim_cur > ARCH_STACK_DEFAULT_SIZE)
 294     limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
 295
 296   /* Make sure it meets the minimum size that allocate_stack
 297      (allocatestack.c) will demand, which depends on the page size.  */
 298   const uintptr_t pagesz = sysconf (_SC_PAGESIZE);
 299   const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
 300   if (limit.rlim_cur < minstack)
 301     limit.rlim_cur = minstack;
 302
 303   /* Round the resource limit up to page size.  */
 304   limit.rlim_cur = (limit.rlim_cur + pagesz - 1) & -pagesz;
 305   __default_stacksize = limit.rlim_cur;
 306
 307 #ifdef SHARED
 308   /* Transfer the old value from the dynamic linker's internal location.  */
 309   *__libc_dl_error_tsd () = *(*GL(dl_error_catch_tsd)) ();
 310   GL(dl_error_catch_tsd) = &__libc_dl_error_tsd;
 311
 312 #endif
 313
 314   GL(dl_init_static_tls) = &__pthread_init_static_tls;
 315
 316   /* Register the fork generation counter with the libc.  */
 317 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
 318   __libc_multiple_threads_ptr =
 319 #endif
 320     __libc_pthread_init (&__fork_generation, __reclaim_stacks);
 321
 322   /* Determine whether the machine is SMP or not.  */
 323   __is_smp = is_smp_system ();
 324
 325   /* uClibc-specific stdio initialization for threads. */
 326   {
 327     FILE *fp;
 328     _stdio_user_locking = 0;       /* 2 if threading not initialized */
 329     for (fp = _stdio_openlist; fp != NULL; fp = fp->__nextopen) {
 330       if (fp->__user_locking != 1) {
 331         fp->__user_locking = 0;
 332       }
 333     }
 334   }
 335 }
 336 strong_alias (__pthread_initialize_minimal_internal,
 337               __pthread_initialize_minimal)