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glibc  2.9
init.c
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00001 /* Copyright (C) 2002,2003,2004,2005,2006,2007 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <assert.h>
00021 #include <limits.h>
00022 #include <signal.h>
00023 #include <stdlib.h>
00024 #include <unistd.h>
00025 #include <sys/param.h>
00026 #include <sys/resource.h>
00027 #include <pthreadP.h>
00028 #include <atomic.h>
00029 #include <ldsodefs.h>
00030 #include <tls.h>
00031 #include <fork.h>
00032 #include <version.h>
00033 #include <shlib-compat.h>
00034 #include <smp.h>
00035 #include <lowlevellock.h>
00036 #include <kernel-features.h>
00037 
00038 
00039 /* Size and alignment of static TLS block.  */
00040 size_t __static_tls_size;
00041 size_t __static_tls_align_m1;
00042 
00043 #ifndef __ASSUME_SET_ROBUST_LIST
00044 /* Negative if we do not have the system call and we can use it.  */
00045 int __set_robust_list_avail;
00046 # define set_robust_list_not_avail() \
00047   __set_robust_list_avail = -1
00048 #else
00049 # define set_robust_list_not_avail() do { } while (0)
00050 #endif
00051 
00052 /* Version of the library, used in libthread_db to detect mismatches.  */
00053 static const char nptl_version[] __attribute_used__ = VERSION;
00054 
00055 
00056 #ifndef SHARED
00057 extern void __libc_setup_tls (size_t tcbsize, size_t tcbalign);
00058 #endif
00059 
00060 
00061 #ifdef SHARED
00062 static const struct pthread_functions pthread_functions =
00063   {
00064     .ptr_pthread_attr_destroy = __pthread_attr_destroy,
00065 # if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
00066     .ptr___pthread_attr_init_2_0 = __pthread_attr_init_2_0,
00067 # endif
00068     .ptr___pthread_attr_init_2_1 = __pthread_attr_init_2_1,
00069     .ptr_pthread_attr_getdetachstate = __pthread_attr_getdetachstate,
00070     .ptr_pthread_attr_setdetachstate = __pthread_attr_setdetachstate,
00071     .ptr_pthread_attr_getinheritsched = __pthread_attr_getinheritsched,
00072     .ptr_pthread_attr_setinheritsched = __pthread_attr_setinheritsched,
00073     .ptr_pthread_attr_getschedparam = __pthread_attr_getschedparam,
00074     .ptr_pthread_attr_setschedparam = __pthread_attr_setschedparam,
00075     .ptr_pthread_attr_getschedpolicy = __pthread_attr_getschedpolicy,
00076     .ptr_pthread_attr_setschedpolicy = __pthread_attr_setschedpolicy,
00077     .ptr_pthread_attr_getscope = __pthread_attr_getscope,
00078     .ptr_pthread_attr_setscope = __pthread_attr_setscope,
00079     .ptr_pthread_condattr_destroy = __pthread_condattr_destroy,
00080     .ptr_pthread_condattr_init = __pthread_condattr_init,
00081     .ptr___pthread_cond_broadcast = __pthread_cond_broadcast,
00082     .ptr___pthread_cond_destroy = __pthread_cond_destroy,
00083     .ptr___pthread_cond_init = __pthread_cond_init,
00084     .ptr___pthread_cond_signal = __pthread_cond_signal,
00085     .ptr___pthread_cond_wait = __pthread_cond_wait,
00086     .ptr___pthread_cond_timedwait = __pthread_cond_timedwait,
00087 # if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_3_2)
00088     .ptr___pthread_cond_broadcast_2_0 = __pthread_cond_broadcast_2_0,
00089     .ptr___pthread_cond_destroy_2_0 = __pthread_cond_destroy_2_0,
00090     .ptr___pthread_cond_init_2_0 = __pthread_cond_init_2_0,
00091     .ptr___pthread_cond_signal_2_0 = __pthread_cond_signal_2_0,
00092     .ptr___pthread_cond_wait_2_0 = __pthread_cond_wait_2_0,
00093     .ptr___pthread_cond_timedwait_2_0 = __pthread_cond_timedwait_2_0,
00094 # endif
00095     .ptr_pthread_equal = __pthread_equal,
00096     .ptr___pthread_exit = __pthread_exit,
00097     .ptr_pthread_getschedparam = __pthread_getschedparam,
00098     .ptr_pthread_setschedparam = __pthread_setschedparam,
00099     .ptr_pthread_mutex_destroy = INTUSE(__pthread_mutex_destroy),
00100     .ptr_pthread_mutex_init = INTUSE(__pthread_mutex_init),
00101     .ptr_pthread_mutex_lock = INTUSE(__pthread_mutex_lock),
00102     .ptr_pthread_mutex_unlock = INTUSE(__pthread_mutex_unlock),
00103     .ptr_pthread_self = __pthread_self,
00104     .ptr_pthread_setcancelstate = __pthread_setcancelstate,
00105     .ptr_pthread_setcanceltype = __pthread_setcanceltype,
00106     .ptr___pthread_cleanup_upto = __pthread_cleanup_upto,
00107     .ptr___pthread_once = __pthread_once_internal,
00108     .ptr___pthread_rwlock_rdlock = __pthread_rwlock_rdlock_internal,
00109     .ptr___pthread_rwlock_wrlock = __pthread_rwlock_wrlock_internal,
00110     .ptr___pthread_rwlock_unlock = __pthread_rwlock_unlock_internal,
00111     .ptr___pthread_key_create = __pthread_key_create_internal,
00112     .ptr___pthread_getspecific = __pthread_getspecific_internal,
00113     .ptr___pthread_setspecific = __pthread_setspecific_internal,
00114     .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer,
00115     .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore,
00116     .ptr_nthreads = &__nptl_nthreads,
00117     .ptr___pthread_unwind = &__pthread_unwind,
00118     .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd,
00119     .ptr__nptl_setxid = __nptl_setxid,
00120     /* For now only the stack cache needs to be freed.  */
00121     .ptr_freeres = __free_stack_cache
00122   };
00123 # define ptr_pthread_functions &pthread_functions
00124 #else
00125 # define ptr_pthread_functions NULL
00126 #endif
00127 
00128 
00129 /* For asynchronous cancellation we use a signal.  This is the handler.  */
00130 static void
00131 sigcancel_handler (int sig, siginfo_t *si, void *ctx)
00132 {
00133 #ifdef __ASSUME_CORRECT_SI_PID
00134   /* Determine the process ID.  It might be negative if the thread is
00135      in the middle of a fork() call.  */
00136   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
00137   if (__builtin_expect (pid < 0, 0))
00138     pid = -pid;
00139 #endif
00140 
00141   /* Safety check.  It would be possible to call this function for
00142      other signals and send a signal from another process.  This is not
00143      correct and might even be a security problem.  Try to catch as
00144      many incorrect invocations as possible.  */
00145   if (sig != SIGCANCEL
00146 #ifdef __ASSUME_CORRECT_SI_PID
00147       /* Kernels before 2.5.75 stored the thread ID and not the process
00148         ID in si_pid so we skip this test.  */
00149       || si->si_pid != pid
00150 #endif
00151       || si->si_code != SI_TKILL)
00152     return;
00153 
00154   struct pthread *self = THREAD_SELF;
00155 
00156   int oldval = THREAD_GETMEM (self, cancelhandling);
00157   while (1)
00158     {
00159       /* We are canceled now.  When canceled by another thread this flag
00160         is already set but if the signal is directly send (internally or
00161         from another process) is has to be done here.  */
00162       int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
00163 
00164       if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
00165        /* Already canceled or exiting.  */
00166        break;
00167 
00168       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
00169                                          oldval);
00170       if (curval == oldval)
00171        {
00172          /* Set the return value.  */
00173          THREAD_SETMEM (self, result, PTHREAD_CANCELED);
00174 
00175          /* Make sure asynchronous cancellation is still enabled.  */
00176          if ((newval & CANCELTYPE_BITMASK) != 0)
00177            /* Run the registered destructors and terminate the thread.  */
00178            __do_cancel ();
00179 
00180          break;
00181        }
00182 
00183       oldval = curval;
00184     }
00185 }
00186 
00187 
00188 struct xid_command *__xidcmd attribute_hidden;
00189 
00190 /* For asynchronous cancellation we use a signal.  This is the handler.  */
00191 static void
00192 sighandler_setxid (int sig, siginfo_t *si, void *ctx)
00193 {
00194 #ifdef __ASSUME_CORRECT_SI_PID
00195   /* Determine the process ID.  It might be negative if the thread is
00196      in the middle of a fork() call.  */
00197   pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
00198   if (__builtin_expect (pid < 0, 0))
00199     pid = -pid;
00200 #endif
00201 
00202   /* Safety check.  It would be possible to call this function for
00203      other signals and send a signal from another process.  This is not
00204      correct and might even be a security problem.  Try to catch as
00205      many incorrect invocations as possible.  */
00206   if (sig != SIGSETXID
00207 #ifdef __ASSUME_CORRECT_SI_PID
00208       /* Kernels before 2.5.75 stored the thread ID and not the process
00209         ID in si_pid so we skip this test.  */
00210       || si->si_pid != pid
00211 #endif
00212       || si->si_code != SI_TKILL)
00213     return;
00214 
00215   INTERNAL_SYSCALL_DECL (err);
00216   INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, err, 3, __xidcmd->id[0],
00217                      __xidcmd->id[1], __xidcmd->id[2]);
00218 
00219   if (atomic_decrement_val (&__xidcmd->cntr) == 0)
00220     lll_futex_wake (&__xidcmd->cntr, 1, LLL_PRIVATE);
00221 
00222   /* Reset the SETXID flag.  */
00223   struct pthread *self = THREAD_SELF;
00224   int flags = THREAD_GETMEM (self, cancelhandling);
00225   THREAD_SETMEM (self, cancelhandling, flags & ~SETXID_BITMASK);
00226 
00227   /* And release the futex.  */
00228   self->setxid_futex = 1;
00229   lll_futex_wake (&self->setxid_futex, 1, LLL_PRIVATE);
00230 }
00231 
00232 
00233 /* When using __thread for this, we do it in libc so as not
00234    to give libpthread its own TLS segment just for this.  */
00235 extern void **__libc_dl_error_tsd (void) __attribute__ ((const));
00236 
00237 
00238 /* This can be set by the debugger before initialization is complete.  */
00239 static bool __nptl_initial_report_events;
00240 
00241 void
00242 __pthread_initialize_minimal_internal (void)
00243 {
00244 #ifndef SHARED
00245   /* Unlike in the dynamically linked case the dynamic linker has not
00246      taken care of initializing the TLS data structures.  */
00247   __libc_setup_tls (TLS_TCB_SIZE, TLS_TCB_ALIGN);
00248 
00249   /* We must prevent gcc from being clever and move any of the
00250      following code ahead of the __libc_setup_tls call.  This function
00251      will initialize the thread register which is subsequently
00252      used.  */
00253   __asm __volatile ("");
00254 #endif
00255 
00256   /* Minimal initialization of the thread descriptor.  */
00257   struct pthread *pd = THREAD_SELF;
00258   INTERNAL_SYSCALL_DECL (err);
00259   pd->pid = pd->tid = INTERNAL_SYSCALL (set_tid_address, err, 1, &pd->tid);
00260   THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
00261   THREAD_SETMEM (pd, user_stack, true);
00262   if (LLL_LOCK_INITIALIZER != 0)
00263     THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
00264 #if HP_TIMING_AVAIL
00265   THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
00266 #endif
00267 
00268   /* Initialize the robust mutex data.  */
00269 #ifdef __PTHREAD_MUTEX_HAVE_PREV
00270   pd->robust_prev = &pd->robust_head;
00271 #endif
00272   pd->robust_head.list = &pd->robust_head;
00273 #ifdef __NR_set_robust_list
00274   pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
00275                               - offsetof (pthread_mutex_t,
00276                                          __data.__list.__next));
00277   int res = INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
00278                            sizeof (struct robust_list_head));
00279   if (INTERNAL_SYSCALL_ERROR_P (res, err))
00280 #endif
00281     set_robust_list_not_avail ();
00282 
00283 #ifndef __ASSUME_PRIVATE_FUTEX
00284   /* Private futexes are always used (at least internally) so that
00285      doing the test once this early is beneficial.  */
00286   {
00287     int word = 0;
00288     word = INTERNAL_SYSCALL (futex, err, 3, &word,
00289                          FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1);
00290     if (!INTERNAL_SYSCALL_ERROR_P (word, err))
00291       THREAD_SETMEM (pd, header.private_futex, FUTEX_PRIVATE_FLAG);
00292   }
00293 #endif
00294 
00295   /* Set initial thread's stack block from 0 up to __libc_stack_end.
00296      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
00297      purposes this is good enough.  */
00298   THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
00299 
00300   /* Initialize the list of all running threads with the main thread.  */
00301   INIT_LIST_HEAD (&__stack_user);
00302   list_add (&pd->list, &__stack_user);
00303 
00304   /* Before initializing __stack_user, the debugger could not find us and
00305      had to set __nptl_initial_report_events.  Propagate its setting.  */
00306   THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
00307 
00308   /* Install the cancellation signal handler.  If for some reason we
00309      cannot install the handler we do not abort.  Maybe we should, but
00310      it is only asynchronous cancellation which is affected.  */
00311   struct sigaction sa;
00312   sa.sa_sigaction = sigcancel_handler;
00313   sa.sa_flags = SA_SIGINFO;
00314   __sigemptyset (&sa.sa_mask);
00315 
00316   (void) __libc_sigaction (SIGCANCEL, &sa, NULL);
00317 
00318   /* Install the handle to change the threads' uid/gid.  */
00319   sa.sa_sigaction = sighandler_setxid;
00320   sa.sa_flags = SA_SIGINFO | SA_RESTART;
00321 
00322   (void) __libc_sigaction (SIGSETXID, &sa, NULL);
00323 
00324   /* The parent process might have left the signals blocked.  Just in
00325      case, unblock it.  We reuse the signal mask in the sigaction
00326      structure.  It is already cleared.  */
00327   __sigaddset (&sa.sa_mask, SIGCANCEL);
00328   __sigaddset (&sa.sa_mask, SIGSETXID);
00329   (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &sa.sa_mask,
00330                         NULL, _NSIG / 8);
00331 
00332   /* Get the size of the static and alignment requirements for the TLS
00333      block.  */
00334   size_t static_tls_align;
00335   _dl_get_tls_static_info (&__static_tls_size, &static_tls_align);
00336 
00337   /* Make sure the size takes all the alignments into account.  */
00338   if (STACK_ALIGN > static_tls_align)
00339     static_tls_align = STACK_ALIGN;
00340   __static_tls_align_m1 = static_tls_align - 1;
00341 
00342   __static_tls_size = roundup (__static_tls_size, static_tls_align);
00343 
00344   /* Determine the default allowed stack size.  This is the size used
00345      in case the user does not specify one.  */
00346   struct rlimit limit;
00347   if (getrlimit (RLIMIT_STACK, &limit) != 0
00348       || limit.rlim_cur == RLIM_INFINITY)
00349     /* The system limit is not usable.  Use an architecture-specific
00350        default.  */
00351     limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE;
00352   else if (limit.rlim_cur < PTHREAD_STACK_MIN)
00353     /* The system limit is unusably small.
00354        Use the minimal size acceptable.  */
00355     limit.rlim_cur = PTHREAD_STACK_MIN;
00356 
00357   /* Make sure it meets the minimum size that allocate_stack
00358      (allocatestack.c) will demand, which depends on the page size.  */
00359   const uintptr_t pagesz = __sysconf (_SC_PAGESIZE);
00360   const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK;
00361   if (limit.rlim_cur < minstack)
00362     limit.rlim_cur = minstack;
00363 
00364   /* Round the resource limit up to page size.  */
00365   limit.rlim_cur = (limit.rlim_cur + pagesz - 1) & -pagesz;
00366   __default_stacksize = limit.rlim_cur;
00367 
00368 #ifdef SHARED
00369   /* Transfer the old value from the dynamic linker's internal location.  */
00370   *__libc_dl_error_tsd () = *(*GL(dl_error_catch_tsd)) ();
00371   GL(dl_error_catch_tsd) = &__libc_dl_error_tsd;
00372 
00373   /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock,
00374      keep the lock count from the ld.so implementation.  */
00375   GL(dl_rtld_lock_recursive) = (void *) INTUSE (__pthread_mutex_lock);
00376   GL(dl_rtld_unlock_recursive) = (void *) INTUSE (__pthread_mutex_unlock);
00377   unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count;
00378   GL(dl_load_lock).mutex.__data.__count = 0;
00379   while (rtld_lock_count-- > 0)
00380     INTUSE (__pthread_mutex_lock) (&GL(dl_load_lock).mutex);
00381 
00382   GL(dl_make_stack_executable_hook) = &__make_stacks_executable;
00383 #endif
00384 
00385   GL(dl_init_static_tls) = &__pthread_init_static_tls;
00386 
00387   GL(dl_wait_lookup_done) = &__wait_lookup_done;
00388 
00389   /* Register the fork generation counter with the libc.  */
00390 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
00391   __libc_multiple_threads_ptr =
00392 #endif
00393     __libc_pthread_init (&__fork_generation, __reclaim_stacks,
00394                       ptr_pthread_functions);
00395 
00396   /* Determine whether the machine is SMP or not.  */
00397   __is_smp = is_smp_system ();
00398 }
00399 strong_alias (__pthread_initialize_minimal_internal,
00400              __pthread_initialize_minimal)