nptl/sysdeps/unix/sysv/linux/i386/createthread.c

   1 /* Copyright (C) 2002-2014 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 /* The "thread register" gets initialized from a segment descriptor.
  20    Initialize such a descriptor first.  */
  21 #define PREPARE_CREATE \
  22   union user_desc_init desc;                                                  \
  23                                                                               \
  24   /* Describe the thread-local storage segment.  */                           \
  25                                                                               \
  26   /* The 'entry_number' field.  The first three bits of the segment           \
  27      register value select the GDT, ignore them.  We get the index            \
  28      from the value of the %gs register in the current thread.  */            \
  29   desc.vals[0] = TLS_GET_GS () >> 3;                                          \
  30   /* The 'base_addr' field.  Pointer to the TCB.  */                          \
  31   desc.vals[1] = (unsigned long int) pd;                                      \
  32   /* The 'limit' field.  We use 4GB which is 0xfffff pages.  */               \
  33   desc.vals[2] = 0xfffff;                                                     \
  34   /* Collapsed value of the bitfield:                                         \
  35        .seg_32bit = 1                                                         \
  36        .contents = 0                                                          \
  37        .read_exec_only = 0                                                    \
  38        .limit_in_pages = 1                                                    \
  39        .seg_not_present = 0                                                   \
  40        .useable = 1 */                                                        \
  41   desc.vals[3] = 0x51
  42
  43 /* Value passed to 'clone' for initialization of the thread register.  */
  44 #define TLS_VALUE &desc.desc
  45
  46
  47 /* Get the real implementation.  */
  48 #include <nptl/sysdeps/pthread/createthread.c>