sysdeps/x86_64/dl-tlsdesc.h

   1 /* Thread-local storage descriptor handling in the ELF dynamic linker.
   2    x86_64 version.
   3    Copyright (C) 2005-2023 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <stdint.h>
  21
  22 #ifndef _X86_64_DL_TLSDESC_H
  23 # define _X86_64_DL_TLSDESC_H 1
  24
  25 /* Type used to represent a TLS descriptor in the GOT.  */
  26 struct tlsdesc
  27 {
  28   /* Anonymous union is used here to ensure that GOT entry slot is always
  29      8 bytes for both x32 and x86-64.  */
  30   union
  31     {
  32       ptrdiff_t (*entry) (struct tlsdesc *on_rax);
  33       uint64_t entry_slot;
  34     };
  35   union
  36     {
  37       void *arg;
  38       uint64_t arg_slot;
  39     };
  40 };
  41
  42 typedef struct dl_tls_index
  43 {
  44   uint64_t ti_module;
  45   uint64_t ti_offset;
  46 } tls_index;
  47
  48 /* Type used as the argument in a TLS descriptor for a symbol that
  49    needs dynamic TLS offsets.  */
  50 struct tlsdesc_dynamic_arg
  51 {
  52   tls_index tlsinfo;
  53   size_t gen_count;
  54 };
  55
  56 extern ptrdiff_t attribute_hidden
  57   _dl_tlsdesc_return(struct tlsdesc *on_rax),
  58   _dl_tlsdesc_undefweak(struct tlsdesc *on_rax);
  59
  60 # ifdef SHARED
  61 extern void *_dl_make_tlsdesc_dynamic (struct link_map *map,
  62                                        size_t ti_offset)
  63   attribute_hidden;
  64
  65 extern ptrdiff_t attribute_hidden _dl_tlsdesc_dynamic(struct tlsdesc *);
  66 # endif
  67
  68 #endif