ldso/include/tlsdeschtab.h

   1 /* Hash table for TLS descriptors.
   2    Copyright (C) 2005-2013 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Alexandre Oliva  <aoliva@redhat.com>
   5
   6    uClibc port by Baruch Siach <baruch@tkos.co.il>
   7
   8    The GNU C Library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU Lesser General Public
  10    License as published by the Free Software Foundation; either
  11    version 2.1 of the License, or (at your option) any later version.
  12
  13    The GNU C Library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    Lesser General Public License for more details.
  17
  18    You should have received a copy of the GNU Lesser General Public
  19    License along with the GNU C Library; if not, see
  20    <http://www.gnu.org/licenses/>.  */
  21
  22 #ifndef TLSDESCHTAB_H
  23 # define TLSDESCHTAB_H 1
  24
  25 # ifdef SHARED
  26
  27 #  include <inline-hashtab.h>
  28
  29 inline static int
  30 hash_tlsdesc (void *p)
  31 {
  32   struct tlsdesc_dynamic_arg *td = p;
  33
  34   /* We know all entries are for the same module, so ti_offset is the
  35      only distinguishing entry.  */
  36   return td->tlsinfo.ti_offset;
  37 }
  38
  39 inline static int
  40 eq_tlsdesc (void *p, void *q)
  41 {
  42   struct tlsdesc_dynamic_arg *tdp = p, *tdq = q;
  43
  44   return tdp->tlsinfo.ti_offset == tdq->tlsinfo.ti_offset;
  45 }
  46
  47 inline static int
  48 map_generation (struct link_map *map)
  49 {
  50   size_t idx = map->l_tls_modid;
  51   struct dtv_slotinfo_list *listp = GL(dl_tls_dtv_slotinfo_list);
  52
  53   /* Find the place in the dtv slotinfo list.  */
  54   do
  55     {
  56       /* Does it fit in the array of this list element?  */
  57       if (idx < listp->len)
  58         {
  59           /* We should never get here for a module in static TLS, so
  60              we can assume that, if the generation count is zero, we
  61              still haven't determined the generation count for this
  62              module.  */
  63           if (listp->slotinfo[idx].gen)
  64             return listp->slotinfo[idx].gen;
  65           else
  66             break;
  67         }
  68       idx -= listp->len;
  69       listp = listp->next;
  70     }
  71   while (listp != NULL);
  72
  73   /* If we get to this point, the module still hasn't been assigned an
  74      entry in the dtv slotinfo data structures, and it will when we're
  75      done with relocations.  At that point, the module will get a
  76      generation number that is one past the current generation, so
  77      return exactly that.  */
  78   return GL(dl_tls_generation) + 1;
  79 }
  80
  81 void *
  82 internal_function
  83 _dl_make_tlsdesc_dynamic (struct link_map *map, size_t ti_offset)
  84 {
  85   struct funcdesc_ht *ht;
  86   void **entry;
  87   struct tlsdesc_dynamic_arg *td, test;
  88
  89   ht = map->l_tlsdesc_table;
  90   if (! ht)
  91     {
  92       ht = htab_create ();
  93       if (! ht)
  94           return 0;
  95       map->l_tlsdesc_table = ht;
  96     }
  97
  98   test.tlsinfo.ti_module = map->l_tls_modid;
  99   test.tlsinfo.ti_offset = ti_offset;
 100   entry = htab_find_slot (ht, &test, 1, hash_tlsdesc, eq_tlsdesc);
 101   if (entry == NULL)
 102     _dl_exit(1);
 103   if (*entry)
 104     {
 105       td = *entry;
 106       return td;
 107     }
 108
 109   *entry = td = _dl_malloc (sizeof (struct tlsdesc_dynamic_arg));
 110   /* This may be higher than the map's generation, but it doesn't
 111      matter much.  Worst case, we'll have one extra DTV update per
 112      thread.  */
 113   td->gen_count = map_generation (map);
 114   td->tlsinfo = test.tlsinfo;
 115
 116   return td;
 117 }
 118
 119 # endif /* SHARED */
 120
 121 #endif