csu/libc-tls.c

   1 /* Initialization code for TLS in statically linked application.
   2    Copyright (C) 2002, 2003, 2004, 2005, 2006 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <ldsodefs.h>
  22 #include <tls.h>
  23 #include <unistd.h>
  24 #include <stdio.h>
  25 #include <sys/param.h>
  26
  27
  28 #ifdef SHARED
  29  #error makefile bug, this file is for static only
  30 #endif
  31
  32 extern ElfW(Phdr) *_dl_phdr;
  33 extern size_t _dl_phnum;
  34
  35
  36 static dtv_t static_dtv[2 + TLS_SLOTINFO_SURPLUS];
  37
  38
  39 static struct
  40 {
  41   struct dtv_slotinfo_list si;
  42   /* The dtv_slotinfo_list data structure does not include the actual
  43      information since it is defined as an array of size zero.  We define
  44      here the necessary entries.  Note that it is not important whether
  45      there is padding or not since we will always access the information
  46      through the 'si' element.  */
  47   struct dtv_slotinfo info[2 + TLS_SLOTINFO_SURPLUS];
  48 } static_slotinfo;
  49
  50 /* Fake link map for the application.  */
  51 static struct link_map static_map;
  52
  53
  54 /* Highest dtv index currently needed.  */
  55 size_t _dl_tls_max_dtv_idx;
  56 /* Flag signalling whether there are gaps in the module ID allocation.  */
  57 bool _dl_tls_dtv_gaps;
  58 /* Information about the dtv slots.  */
  59 struct dtv_slotinfo_list *_dl_tls_dtv_slotinfo_list;
  60 /* Number of modules in the static TLS block.  */
  61 size_t _dl_tls_static_nelem;
  62 /* Size of the static TLS block.  Giving this initialized value
  63    preallocates some surplus bytes in the static TLS area.  */
  64 size_t _dl_tls_static_size = 2048;
  65 /* Size actually allocated in the static TLS block.  */
  66 size_t _dl_tls_static_used;
  67 /* Alignment requirement of the static TLS block.  */
  68 size_t _dl_tls_static_align;
  69
  70 /* Generation counter for the dtv.  */
  71 size_t _dl_tls_generation;
  72
  73
  74 /* Additional definitions needed by TLS initialization.  */
  75 #ifdef TLS_INIT_HELPER
  76 TLS_INIT_HELPER
  77 #endif
  78
  79 static inline void
  80 init_slotinfo (void)
  81 {
  82   /* Create the slotinfo list.  */
  83   static_slotinfo.si.len = (((char *) (&static_slotinfo + 1)
  84                              - (char *) &static_slotinfo.si.slotinfo[0])
  85                             / sizeof static_slotinfo.si.slotinfo[0]);
  86   // static_slotinfo.si.next = NULL;    already zero
  87
  88   /* The slotinfo list.  Will be extended by the code doing dynamic
  89      linking.  */
  90   GL(dl_tls_max_dtv_idx) = 1;
  91   GL(dl_tls_dtv_slotinfo_list) = &static_slotinfo.si;
  92 }
  93
  94 static inline void
  95 init_static_tls (size_t memsz, size_t align)
  96 {
  97   /* That is the size of the TLS memory for this object.  The initialized
  98      value of _dl_tls_static_size is provided by dl-open.c to request some
  99      surplus that permits dynamic loading of modules with IE-model TLS.  */
 100   GL(dl_tls_static_size) = roundup (memsz + GL(dl_tls_static_size),
 101                                     TLS_TCB_ALIGN);
 102   GL(dl_tls_static_used) = memsz;
 103   /* The alignment requirement for the static TLS block.  */
 104   GL(dl_tls_static_align) = align;
 105   /* Number of elements in the static TLS block.  */
 106   GL(dl_tls_static_nelem) = GL(dl_tls_max_dtv_idx);
 107 }
 108
 109 void *__tls_template_start;
 110 void *__tls_template_tdata_end;
 111 void *__tls_template_end;
 112
 113 __asm__(".global __gnacl_tls_init; __gnacl_tls_init = 0x1a40 ");
 114 int __gnacl_tls_init(void const *buf, size_t size);
 115
 116 void
 117 __libc_setup_tls (size_t tcbsize, size_t tcbalign)
 118 {
 119   void *tlsblock;
 120   size_t memsz = 0;
 121   size_t filesz = 0;
 122   void *initimage = NULL;
 123   size_t align = 0;
 124   size_t max_align = tcbalign;
 125   size_t tcb_offset;
 126   ElfW(Phdr) *phdr;
 127
 128 #if 0
 129   /* Look through the TLS segment if there is any.  */
 130   if (_dl_phdr != NULL)
 131     for (phdr = _dl_phdr; phdr < &_dl_phdr[_dl_phnum]; ++phdr)
 132       if (phdr->p_type == PT_TLS)
 133         {
 134           /* Remember the values we need.  */
 135           memsz = phdr->p_memsz;
 136           filesz = phdr->p_filesz;
 137           initimage = (void *) phdr->p_vaddr;
 138           align = phdr->p_align;
 139           if (phdr->p_align > max_align)
 140             max_align = phdr->p_align;
 141           break;
 142         }
 143 #endif
 144   initimage = (void *) &__tls_template_start;
 145   memsz = (size_t) &__tls_template_end - (size_t) &__tls_template_start;
 146   filesz = (size_t) &__tls_template_tdata_end - (size_t) &__tls_template_start;
 147   align = 4;
 148
 149   /* We have to set up the TCB block which also (possibly) contains
 150      'errno'.  Therefore we avoid 'malloc' which might touch 'errno'.
 151      Instead we use 'sbrk' which would only uses 'errno' if it fails.
 152      In this case we are right away out of memory and the user gets
 153      what she/he deserves.
 154
 155      The initialized value of _dl_tls_static_size is provided by dl-open.c
 156      to request some surplus that permits dynamic loading of modules with
 157      IE-model TLS.  */
 158 #if TLS_TCB_AT_TP
 159   tcb_offset = roundup (memsz + GL(dl_tls_static_size), tcbalign);
 160   tlsblock = __sbrk (tcb_offset + tcbsize + max_align);
 161 #elif TLS_DTV_AT_TP
 162   tcb_offset = roundup (tcbsize, align ?: 1);
 163   tlsblock = __sbrk (tcb_offset + memsz + max_align
 164                      + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size));
 165   tlsblock += TLS_PRE_TCB_SIZE;
 166 #else
 167   /* In case a model with a different layout for the TCB and DTV
 168      is defined add another #elif here and in the following #ifs.  */
 169 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
 170 #endif
 171
 172   /* Align the TLS block.  */
 173   tlsblock = (void *) (((uintptr_t) tlsblock + max_align - 1)
 174                        & ~(max_align - 1));
 175
 176   /* Initialize the dtv.  [0] is the length, [1] the generation counter.  */
 177   static_dtv[0].counter = (sizeof (static_dtv) / sizeof (static_dtv[0])) - 2;
 178   // static_dtv[1].counter = 0;         would be needed if not already done
 179
 180   /* Initialize the TLS block.  */
 181 #if TLS_TCB_AT_TP
 182   static_dtv[2].pointer.val = ((char *) tlsblock + tcb_offset
 183                                - roundup (memsz, align ?: 1));
 184   static_map.l_tls_offset = roundup (memsz, align ?: 1);
 185 #elif TLS_DTV_AT_TP
 186   static_dtv[2].pointer.val = (char *) tlsblock + tcb_offset;
 187   static_map.l_tls_offset = tcb_offset;
 188 #else
 189 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
 190 #endif
 191   static_dtv[2].pointer.is_static = true;
 192   /* sbrk gives us zero'd memory, so we don't need to clear the remainder.  */
 193   memcpy (static_dtv[2].pointer.val, initimage, filesz);
 194
 195   /* Install the pointer to the dtv.  */
 196
 197   /* Initialize the thread pointer.  */
 198 #if TLS_TCB_AT_TP
 199   INSTALL_DTV ((char *) tlsblock + tcb_offset, static_dtv);
 200
 201   //const char *lossage = TLS_INIT_TP ((char *) tlsblock + tcb_offset, 0);
 202   __gnacl_tls_init (tlsblock + tcb_offset, 100);
 203   tcbhead_t *head = (void *) tlsblock + tcb_offset;
 204   head->tcb = head;
 205   head->self = head;
 206   const char *lossage = NULL;
 207 #elif TLS_DTV_AT_TP
 208 # error "not supported"
 209   INSTALL_DTV (tlsblock, static_dtv);
 210   const char *lossage = TLS_INIT_TP (tlsblock, 0);
 211 #else
 212 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
 213 #endif
 214   if (__builtin_expect (lossage != NULL, 0))
 215     __libc_fatal (lossage);
 216
 217   /* We have to create a fake link map which normally would be created
 218      by the dynamic linker.  It just has to have enough information to
 219      make the TLS routines happy.  */
 220   static_map.l_tls_align = align;
 221   static_map.l_tls_blocksize = memsz;
 222   static_map.l_tls_initimage = initimage;
 223   static_map.l_tls_initimage_size = filesz;
 224   static_map.l_type = lt_executable;
 225   static_map.l_tls_modid = 1;
 226
 227   init_slotinfo ();
 228   // static_slotinfo.si.slotinfo[1].gen = 0; already zero
 229   static_slotinfo.si.slotinfo[1].map = &static_map;
 230
 231   memsz = roundup (memsz, align ?: 1);
 232
 233 #if TLS_TCB_AT_TP
 234   memsz += tcbsize;
 235 #elif TLS_DTV_AT_TP
 236   memsz += tcb_offset;
 237 #endif
 238
 239   init_static_tls (memsz, MAX (TLS_TCB_ALIGN, max_align));
 240 }
 241
 242 /* This is called only when the data structure setup was skipped at startup,
 243    when there was no need for it then.  Now we have dynamically loaded
 244    something needing TLS, or libpthread needs it.  */
 245 int
 246 internal_function
 247 _dl_tls_setup (void)
 248 {
 249   init_slotinfo ();
 250   init_static_tls (
 251 #if TLS_TCB_AT_TP
 252                    TLS_TCB_SIZE,
 253 #else
 254                    0,
 255 #endif
 256                    TLS_TCB_ALIGN);
 257   return 0;
 258 }
 259
 260
 261 /* This is the minimal initialization function used when libpthread is
 262    not used.  */
 263 void
 264 __attribute__ ((weak))
 265 __pthread_initialize_minimal (void)
 266 {
 267   __libc_setup_tls (TLS_INIT_TCB_SIZE, TLS_INIT_TCB_ALIGN);
 268 }