sysdeps/nptl/dl-tls_init_tp.c

   1 /* Completion of TCB initialization after TLS_INIT_TP.  NPTL version.
   2    Copyright (C) 2020-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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 <kernel-features.h>
  20 #include <ldsodefs.h>
  21 #include <list.h>
  22 #include <pthreadP.h>
  23 #include <tls.h>
  24 #include <rseq-internal.h>
  25 #include <thread_pointer.h>
  26
  27 #define TUNABLE_NAMESPACE pthread
  28 #include <dl-tunables.h>
  29
  30 #ifndef __ASSUME_SET_ROBUST_LIST
  31 bool __nptl_set_robust_list_avail;
  32 rtld_hidden_data_def (__nptl_set_robust_list_avail)
  33 #endif
  34
  35 bool __nptl_initial_report_events;
  36 rtld_hidden_def (__nptl_initial_report_events)
  37
  38 #ifdef SHARED
  39 /* Dummy implementation.  See __rtld_mutex_init.  */
  40 static int
  41 rtld_mutex_dummy (pthread_mutex_t *lock)
  42 {
  43   return 0;
  44 }
  45 #endif
  46
  47 const unsigned int __rseq_flags;
  48 const unsigned int __rseq_size attribute_relro;
  49 const ptrdiff_t __rseq_offset attribute_relro;
  50
  51 void
  52 __tls_pre_init_tp (void)
  53 {
  54   /* The list data structures are not consistent until
  55      initialized.  */
  56   INIT_LIST_HEAD (&GL (dl_stack_used));
  57   INIT_LIST_HEAD (&GL (dl_stack_user));
  58   INIT_LIST_HEAD (&GL (dl_stack_cache));
  59
  60 #ifdef SHARED
  61   ___rtld_mutex_lock = rtld_mutex_dummy;
  62   ___rtld_mutex_unlock = rtld_mutex_dummy;
  63 #endif
  64 }
  65
  66 void
  67 __tls_init_tp (void)
  68 {
  69   struct pthread *pd = THREAD_SELF;
  70
  71   /* Set up thread stack list management.  */
  72   list_add (&pd->list, &GL (dl_stack_user));
  73
  74    /* Early initialization of the TCB.   */
  75    pd->tid = INTERNAL_SYSCALL_CALL (set_tid_address, &pd->tid);
  76    THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
  77    THREAD_SETMEM (pd, user_stack, true);
  78
  79   /* Before initializing GL (dl_stack_user), the debugger could not
  80      find us and had to set __nptl_initial_report_events.  Propagate
  81      its setting.  */
  82   THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);
  83
  84   /* Initialize the robust mutex data.  */
  85   {
  86 #if __PTHREAD_MUTEX_HAVE_PREV
  87     pd->robust_prev = &pd->robust_head;
  88 #endif
  89     pd->robust_head.list = &pd->robust_head;
  90     pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
  91                                     - offsetof (pthread_mutex_t,
  92                                                 __data.__list.__next));
  93     int res = INTERNAL_SYSCALL_CALL (set_robust_list, &pd->robust_head,
  94                                      sizeof (struct robust_list_head));
  95     if (!INTERNAL_SYSCALL_ERROR_P (res))
  96       {
  97 #ifndef __ASSUME_SET_ROBUST_LIST
  98         __nptl_set_robust_list_avail = true;
  99 #endif
 100       }
 101   }
 102
 103   {
 104     bool do_rseq = true;
 105     do_rseq = TUNABLE_GET (rseq, int, NULL);
 106     if (rseq_register_current_thread (pd, do_rseq))
 107       {
 108         /* We need a writable view of the variables.  They are in
 109            .data.relro and are not yet write-protected.  */
 110         extern unsigned int size __asm__ ("__rseq_size");
 111         size = sizeof (pd->rseq_area);
 112       }
 113
 114 #ifdef RSEQ_SIG
 115     /* This should be a compile-time constant, but the current
 116        infrastructure makes it difficult to determine its value.  Not
 117        all targets support __thread_pointer, so set __rseq_offset only
 118        if the rseq registration may have happened because RSEQ_SIG is
 119        defined.  */
 120     extern ptrdiff_t offset __asm__ ("__rseq_offset");
 121     offset = (char *) &pd->rseq_area - (char *) __thread_pointer ();
 122 #endif
 123   }
 124
 125   /* Set initial thread's stack block from 0 up to __libc_stack_end.
 126      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
 127      purposes this is good enough.  */
 128   THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
 129 }