glibc/sysdeps/nptl/dl-tls_init_tp.c

/* Completion of TCB initialization after TLS_INIT_TP.  NPTL version.
   Copyright (C) 2020-2025 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <kernel-features.h>
#include <ldsodefs.h>
#include <list.h>
#include <pthreadP.h>
#include <tls.h>
#include <rseq-internal.h>
#include <thread_pointer.h>

#define TUNABLE_NAMESPACE pthread
#include <dl-tunables.h>

#ifndef __ASSUME_SET_ROBUST_LIST
bool __nptl_set_robust_list_avail;
rtld_hidden_data_def (__nptl_set_robust_list_avail)
#endif

bool __nptl_initial_report_events;
rtld_hidden_def (__nptl_initial_report_events)

#ifdef SHARED
/* Dummy implementation.  See __rtld_mutex_init.  */
static int
rtld_mutex_dummy (pthread_mutex_t *lock)
{
  return 0;
}
#endif

const unsigned int __rseq_flags;

size_t _rseq_align attribute_hidden;

void
__tls_pre_init_tp (void)
{
  /* The list data structures are not consistent until
     initialized.  */
  INIT_LIST_HEAD (&GL (dl_stack_used));
  INIT_LIST_HEAD (&GL (dl_stack_user));
  INIT_LIST_HEAD (&GL (dl_stack_cache));

#ifdef SHARED
  ___rtld_mutex_lock = rtld_mutex_dummy;
  ___rtld_mutex_unlock = rtld_mutex_dummy;
#endif
}

void
__tls_init_tp (void)
{
  struct pthread *pd = THREAD_SELF;

  /* Set up thread stack list management.  */
  list_add (&pd->list, &GL (dl_stack_user));

   /* Early initialization of the TCB.   */
   pd->tid = INTERNAL_SYSCALL_CALL (set_tid_address, &pd->tid);
   THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
   THREAD_SETMEM (pd, stack_mode, ALLOCATE_GUARD_USER);

  /* Before initializing GL (dl_stack_user), the debugger could not
     find us and had to set __nptl_initial_report_events.  Propagate
     its setting.  */
  THREAD_SETMEM (pd, report_events, __nptl_initial_report_events);

  /* Initialize the robust mutex data.  */
  {
#if __PTHREAD_MUTEX_HAVE_PREV
    pd->robust_prev = &pd->robust_head;
#endif
    pd->robust_head.list = &pd->robust_head;
    pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
                                    - offsetof (pthread_mutex_t,
                                                __data.__list.__next));
    int res = INTERNAL_SYSCALL_CALL (set_robust_list, &pd->robust_head,
                                     sizeof (struct robust_list_head));
    if (!INTERNAL_SYSCALL_ERROR_P (res))
      {
#ifndef __ASSUME_SET_ROBUST_LIST
        __nptl_set_robust_list_avail = true;
#endif
      }
  }

  {
    /* If the registration fails or is disabled by tunable, the public
       '__rseq_size' will be set to '0' regardless of the feature size of the
       allocated rseq area.  An rseq area of at least 32 bytes is always
       allocated since application code is allowed to check the status of the
       rseq registration by reading the content of the 'cpu_id' field.  */
    bool do_rseq = TUNABLE_GET (rseq, int, NULL);
    if (!rseq_register_current_thread (pd, do_rseq))
      _rseq_size = 0;
  }

  /* Set initial thread's stack block from 0 up to __libc_stack_end.
     It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
     purposes this is good enough.  */
  THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
}