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 #ifdef __ASSUME_CORRECT_SI_PID
  68   /* Determine the process ID.  It might be negative if the thread is
  69      in the middle of a fork() call.  */
  70   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
  71   if (__builtin_expect (pid < 0, 0))
  72     pid = -pid;
  73 #endif
  74
  75   /* Safety check.  It would be possible to call this function for
  76      other signals and send a signal from another process.  This is not
  77      correct and might even be a security problem.  Try to catch as
  78      many incorrect invocations as possible.  */
  79   if (sig != SIGCANCEL
  80 #ifdef __ASSUME_CORRECT_SI_PID
  81       /* Kernels before 2.5.75 stored the thread ID and not the process
  82          ID in si_pid so we skip this test.  */
  83       || si->si_pid != pid
  84 #endif
  85       || si->si_code != SI_TKILL)
  86     return;
  87
  88   struct pthread *self = THREAD_SELF;
  89
  90   int oldval = THREAD_GETMEM (self, cancelhandling);
  91   while (1)
  92     {
  93       /* We are canceled now.  When canceled by another thread this flag
  94          is already set but if the signal is directly send (internally or
  95          from another process) is has to be done here.  */
  96       int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
  97
  98       if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
  99         /* Already canceled or exiting.  */
 100         break;
 101
 102       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
 103                                               oldval);
 104       if (curval == oldval)
 105         {
 106           /* Set the return value.  */
 107           THREAD_SETMEM (self, result, PTHREAD_CANCELED);
 108
 109           /* Make sure asynchronous cancellation is still enabled.  */
 110           if ((newval & CANCELTYPE_BITMASK) != 0)
 111             /* Run the registered destructors and terminate the thread.  */
 112             __do_cancel ();
 113
 114           break;
 115         }
 116
 117       oldval = curval;
 118     }
 119 }
 120
 121
 122 struct xid_command *__xidcmd attribute_hidden;
 123
 124 /* For asynchronous cancellation we use a signal.  This is the handler.  */
 125 static void
 126 sighandler_setxid (int sig, siginfo_t *si, void *ctx)
 127 {
 128 #ifdef __ASSUME_CORRECT_SI_PID
 129   /* Determine the process ID.  It might be negative if the thread is
 130      in the middle of a fork() call.  */
 131   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
 132   if (__builtin_expect (pid < 0, 0))
 133     pid = -pid;
 134 #endif
 135
 136   /* Safety check.  It would be possible to call this function for
 137      other signals and send a signal from another process.  This is not
 138      correct and might even be a security problem.  Try to catch as
 139      many incorrect invocations as possible.  */
 140   if (sig != SIGSETXID
 141 #ifdef __ASSUME_CORRECT_SI_PID
 142       /* Kernels before 2.5.75 stored the thread ID and not the process
 143          ID in si_pid so we skip this test.  */
 144       || si->si_pid != pid
 145 #endif
 146       || si->si_code != SI_TKILL)
 147     return;
 148
 149   INTERNAL_SYSCALL_DECL (err);
 150   INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
 151                         __xidcmd->id[1], __xidcmd->id[2]);
 152
 153   /* Reset the SETXID flag.  */
 154   struct pthread *self = THREAD_SELF;
 155   int flags, newval;
 156   do
 157     {
 158       flags = THREAD_GETMEM (self, cancelhandling);
 159       newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
 160                                           flags & ~SETXID_BITMASK, flags);
 161     }
 162   while (flags != newval);
 163
 164   /* And release the futex.  */
 165   self->setxid_futex = 1;
 166   lll_futex_wake (&self->setxid_futex, 1, LLL_PRIVATE);
 167
 168   if (atomic_decrement_val (&__xidcmd->cntr) == 0)
 169     lll_futex_wake (&__xidcmd->cntr, 1, LLL_PRIVATE);
 170 }
 171
 172
 173 /* When using __thread for this, we do it in libc so as not
 174    to give libpthread its own TLS segment just for this.  */
 175 extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
 176
 177
 178 /* This can be set by the debugger before initialization is complete.  */
 179 static bool __nptl_initial_report_events __attribute_used__;
 180
 181 void __pthread_initialize_minimal_internal (void) attribute_hidden;
 182 void
 183 __pthread_initialize_minimal_internal (void)
 184 {
 185   static int initialized = 0;
 186
 187   if (initialized)
 188     return;
 189   initialized = 1;
 190
 191   /* Minimal initialization of the thread descriptor.  */
 192   struct pthread *pd = THREAD_SELF;
 193   INTERNAL_SYSCALL_DECL (err);
 194   pd->pid = pd->tid = INTERNAL_SYSCALL (set_tid_address, err, 1, &pd->tid);
 195   THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
 196   THREAD_SETMEM (pd, user_stack, true);
 197   if (LLL_LOCK_INITIALIZER != 0)
 198     THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
 199 #if HP_TIMING_AVAIL
 200   THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
 201 #endif
 202
 203   /* Initialize the robust mutex data.  */
 204 #ifdef __PTHREAD_MUTEX_HAVE_PREV
 205   pd->robust_prev = &pd->robust_head;
 206 #endif
 207   pd->robust_head.list = &pd->robust_head;
 208 #ifdef __NR_set_robust_list
 209   pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
 210                                   - offsetof (pthread_mutex_t,
 211                                               __data.__list.__next));
 212   int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
 213                               sizeof (struct robust_list_head));
 214   if (INTERNAL_SYSCALL_ERROR_P (res, err))
 215 #endif
 216     set_robust_list_not_avail ();
 217
 218 #ifndef __ASSUME_PRIVATE_FUTEX
 219   /* Private futexes are always used (at least internally) so that
 220      doing the test once this early is beneficial.  */
 221   {
 222     int word = 0;
 223     word = INTERNAL_SYSCALL (futex, err, 3, &word,
 224                             FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1);
 225     if (!INTERNAL_SYSCALL_ERROR_P (word, err))
 226       THREAD_SETMEM (pd, header.private_futex, FUTEX_PRIVATE_FLAG);
 227   }
 228
 229   /* Private futexes have been introduced earlier than the
 230      FUTEX_CLOCK_REALTIME flag.  We don't have to run the test if we
 231      know the former are not supported.  This also means we know the
 232      kernel will return ENOSYS for unknown operations.  */
 233   if (THREAD_GETMEM (pd, header.private_futex) != 0)
 234 #endif
 235 #ifndef __ASSUME_FUTEX_CLOCK_REALTIME
 236     {
 237       int word = 0;
 238       /* NB: the syscall actually takes six parameters.  The last is the
 239          bit mask.  But since we will not actually wait at all the value
 240          is irrelevant.  Given that passing six parameters is difficult
 241          on some architectures we just pass whatever random value the
 242          calling convention calls for to the kernel.  It causes no harm.  */
 243       word = INTERNAL_SYSCALL (futex, err, 5, &word,
 244                                FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME
 245                                | FUTEX_PRIVATE_FLAG, 1, NULL, 0);
 246       assert (INTERNAL_SYSCALL_ERROR_P (word, err));
 247       if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS)
 248         __set_futex_clock_realtime ();
 249     }
 250 #endif
 251
 252   /* Set initial thread's stack block from 0 up to __libc_stack_end.
 253      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
 254      purposes this is good enough.  */
 255   THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
 256
 257   /* Initialize the list of all running threads with the main thread.  */
 258   INIT_LIST_HEAD (&__stack_user);
 259   list_add (&pd->list, &__stack_user);
 260
 261   /* Before initializing __stack_user, the debugger could not find us and
 262      had to set __nptl_initial_report_events.  Propagate its setting.  */
 263   THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
 264
 265   /* Install the cancellation signal handler.  If for some reason we
 266      cannot install the handler we do not abort.  Maybe we should, but
 267      it is only asynchronous cancellation which is affected.  */
 268   struct sigaction sa;
 269   sa.sa_sigaction = sigcancel_handler;
 270   sa.sa_flags = SA_SIGINFO;
 271   __sigemptyset (&sa.sa_mask);
 272
 273   (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
 274
 275   /* Install the handle to change the threads' uid/gid.  */
 276   sa.sa_sigaction = sighandler_setxid;
 277   sa.sa_flags = SA_SIGINFO | SA_RESTART;
 278
 279   (void) __libc_sigaction (SIGSETXID, &sa, NULL);
 280
 281   /* The parent process might have left the signals blocked.  Just in
 282      case, unblock it.  We reuse the signal mask in the sigaction
 283      structure.  It is already cleared.  */
 284   __sigaddset (&sa.sa_mask, SIGCANCEL);
 285   __sigaddset (&sa.sa_mask, SIGSETXID);
 286   (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
 287                            NULL, _NSIG / 8);
 288
 289   /* Get the size of the static and alignment requirements for the TLS
 290      block.  */
 291   size_t static_tls_align;
 292   _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
 293
 294   /* Make sure the size takes all the alignments into account.  */
 295   if (STACK_ALIGN > static_tls_align)
 296     static_tls_align = STACK_ALIGN;
 297   __static_tls_align_m1 = static_tls_align - 1;
 298
 299   __static_tls_size = roundup (__static_tls_size, static_tls_align);
 300
 301   /* Determine the default allowed stack size.  This is the size used
 302      in case the user does not specify one.  */
 303   struct rlimit limit;
 304   if (getrlimit (RLIMIT_STACK, &limit) != 0
 305       || limit.rlim_cur == RLIM_INFINITY)
 306     /* The system limit is not usable.  Use an architecture-specific
 307        default.  */
 308     limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
 309   else if (limit.rlim_cur < PTHREAD_STACK_MIN)
 310     /* The system limit is unusably small.
 311        Use the minimal size acceptable.  */
 312     limit.rlim_cur = PTHREAD_STACK_MIN;
 313
 314   /* Do not exceed architecture specific default */
 315   if (limit.rlim_cur > ARCH_STACK_DEFAULT_SIZE)
 316     limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
 317
 318   /* Make sure it meets the minimum size that allocate_stack
 319      (allocatestack.c) will demand, which depends on the page size.  */
 320   const uintptr_t pagesz = sysconf (_SC_PAGESIZE);
 321   const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
 322   if (limit.rlim_cur < minstack)
 323     limit.rlim_cur = minstack;
 324
 325   /* Round the resource limit up to page size.  */
 326   limit.rlim_cur = (limit.rlim_cur + pagesz - 1) & -pagesz;
 327   __default_stacksize = limit.rlim_cur;
 328
 329 #ifdef SHARED
 330   /* Transfer the old value from the dynamic linker's internal location.  */
 331   *__libc_dl_error_tsd () = *(*GL(dl_error_catch_tsd)) ();
 332   GL(dl_error_catch_tsd) = &__libc_dl_error_tsd;
 333
 334 #endif
 335
 336   GL(dl_init_static_tls) = &__pthread_init_static_tls;
 337
 338   /* Register the fork generation counter with the libc.  */
 339 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
 340   __libc_multiple_threads_ptr =
 341 #endif
 342     __libc_pthread_init (&__fork_generation, __reclaim_stacks);
 343
 344   /* Determine whether the machine is SMP or not.  */
 345   __is_smp = is_smp_system ();
 346
 347   /* uClibc-specific stdio initialization for threads. */
 348   {
 349     FILE *fp;
 350     _stdio_user_locking = 0;       /* 2 if threading not initialized */
 351     for (fp = _stdio_openlist; fp != NULL; fp = fp->__nextopen) {
 352       if (fp->__user_locking != 1) {
 353         fp->__user_locking = 0;
 354       }
 355     }
 356   }
 357 }
 358 strong_alias (__pthread_initialize_minimal_internal,
 359               __pthread_initialize_minimal)