sysdeps/x86_64/dl-tls.c

   1 /* Thread-local storage handling in the ELF dynamic linker.  x86-64 version.
   2    Copyright (C) 2017-2024 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 #ifdef SHARED
  20 /* Work around GCC PR58066, due to which __tls_get_addr may be called
  21    with an unaligned stack.  The compat implementation is in
  22    tls_get_addr-compat.S.  */
  23
  24 # include <dl-tls.h>
  25
  26 /* Define __tls_get_addr within elf/dl-tls.c under a different
  27    name.  */
  28 extern __typeof__ (__tls_get_addr) ___tls_get_addr;
  29
  30 # define __tls_get_addr ___tls_get_addr
  31 # include <elf/dl-tls.c>
  32 # undef __tls_get_addr
  33
  34 hidden_ver (___tls_get_addr, __tls_get_addr)
  35
  36 /* Only handle slow paths for __tls_get_addr.  */
  37 attribute_hidden
  38 void *
  39 __tls_get_addr_slow (GET_ADDR_ARGS)
  40 {
  41   dtv_t *dtv = THREAD_DTV ();
  42
  43   size_t gen = atomic_load_acquire (&GL(dl_tls_generation));
  44   if (__glibc_unlikely (dtv[0].counter != gen)
  45       /* See comment in __tls_get_addr in elf/dl-tls.c.  */
  46       && !(_dl_tls_allocate_active ()
  47            && GET_ADDR_MODULE < _dl_tls_initial_modid_limit))
  48     return update_get_addr (GET_ADDR_PARAM, gen);
  49
  50   return tls_get_addr_tail (GET_ADDR_PARAM, dtv, NULL);
  51 }
  52 #else
  53
  54 /* No compatibility symbol needed.  */
  55 # include <elf/dl-tls.c>
  56
  57 #endif