aboutsummaryrefslogtreecommitdiff
path: root/elf/dl-tls.c
blob: e234a0a82ab3e970fb2a13a4d21e1de4cb13aec0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
/* Thread-local storage handling in the ELF dynamic linker.  Generic version.
   Copyright (C) 2002,2003,2004,2005,2006,2008 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <assert.h>
#include <errno.h>
#include <libintl.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/param.h>

#include <tls.h>
#include <dl-tls.h>
#include <ldsodefs.h>

/* Amount of excess space to allocate in the static TLS area
   to allow dynamic loading of modules defining IE-model TLS data.  */
#define TLS_STATIC_SURPLUS	64 + DL_NNS * 100

/* Value used for dtv entries for which the allocation is delayed.  */
#define TLS_DTV_UNALLOCATED	((void *) -1l)


/* Out-of-memory handler.  */
#ifdef SHARED
static void
__attribute__ ((__noreturn__))
oom (void)
{
  _dl_fatal_printf ("cannot allocate memory for thread-local data: ABORT\n");
}
#endif


size_t
internal_function
_dl_next_tls_modid (void)
{
  size_t result;

  if (__builtin_expect (GL(dl_tls_dtv_gaps), false))
    {
      size_t disp = 0;
      struct dtv_slotinfo_list *runp = GL(dl_tls_dtv_slotinfo_list);

      /* Note that this branch will never be executed during program
	 start since there are no gaps at that time.  Therefore it
	 does not matter that the dl_tls_dtv_slotinfo is not allocated
	 yet when the function is called for the first times.

	 NB: the offset +1 is due to the fact that DTV[0] is used
	 for something else.  */
      result = GL(dl_tls_static_nelem) + 1;
      if (result <= GL(dl_tls_max_dtv_idx))
	do
	  {
	    while (result - disp < runp->len)
	      {
		if (runp->slotinfo[result - disp].map == NULL)
		  break;

		++result;
		assert (result <= GL(dl_tls_max_dtv_idx) + 1);
	      }

	    if (result - disp < runp->len)
	      break;

	    disp += runp->len;
	  }
	while ((runp = runp->next) != NULL);

      if (result > GL(dl_tls_max_dtv_idx))
	{
	  /* The new index must indeed be exactly one higher than the
	     previous high.  */
	  assert (result == GL(dl_tls_max_dtv_idx) + 1);
	  /* There is no gap anymore.  */
	  GL(dl_tls_dtv_gaps) = false;

	  goto nogaps;
	}
    }
  else
    {
      /* No gaps, allocate a new entry.  */
    nogaps:

      result = ++GL(dl_tls_max_dtv_idx);
    }

  return result;
}


#ifdef SHARED
void
internal_function
_dl_determine_tlsoffset (void)
{
  size_t max_align = TLS_TCB_ALIGN;
  size_t freetop = 0;
  size_t freebottom = 0;

  /* The first element of the dtv slot info list is allocated.  */
  assert (GL(dl_tls_dtv_slotinfo_list) != NULL);
  /* There is at this point only one element in the
     dl_tls_dtv_slotinfo_list list.  */
  assert (GL(dl_tls_dtv_slotinfo_list)->next == NULL);

  struct dtv_slotinfo *slotinfo = GL(dl_tls_dtv_slotinfo_list)->slotinfo;

  /* Determining the offset of the various parts of the static TLS
     block has several dependencies.  In addition we have to work
     around bugs in some toolchains.

     Each TLS block from the objects available at link time has a size
     and an alignment requirement.  The GNU ld computes the alignment
     requirements for the data at the positions *in the file*, though.
     I.e, it is not simply possible to allocate a block with the size
     of the TLS program header entry.  The data is layed out assuming
     that the first byte of the TLS block fulfills

       p_vaddr mod p_align == &TLS_BLOCK mod p_align

     This means we have to add artificial padding at the beginning of
     the TLS block.  These bytes are never used for the TLS data in
     this module but the first byte allocated must be aligned
     according to mod p_align == 0 so that the first byte of the TLS
     block is aligned according to p_vaddr mod p_align.  This is ugly
     and the linker can help by computing the offsets in the TLS block
     assuming the first byte of the TLS block is aligned according to
     p_align.

     The extra space which might be allocated before the first byte of
     the TLS block need not go unused.  The code below tries to use
     that memory for the next TLS block.  This can work if the total
     memory requirement for the next TLS block is smaller than the
     gap.  */

#if TLS_TCB_AT_TP
  /* We simply start with zero.  */
  size_t offset = 0;

  for (size_t cnt = 0; slotinfo[cnt].map != NULL; ++cnt)
    {
      assert (cnt < GL(dl_tls_dtv_slotinfo_list)->len);

      size_t firstbyte = (-slotinfo[cnt].map->l_tls_firstbyte_offset
			  & (slotinfo[cnt].map->l_tls_align - 1));
      size_t off;
      max_align = MAX (max_align, slotinfo[cnt].map->l_tls_align);

      if (freebottom - freetop >= slotinfo[cnt].map->l_tls_blocksize)
	{
	  off = roundup (freetop + slotinfo[cnt].map->l_tls_blocksize
			 - firstbyte, slotinfo[cnt].map->l_tls_align)
		+ firstbyte;
	  if (off <= freebottom)
	    {
	      freetop = off;

	      /* XXX For some architectures we perhaps should store the
		 negative offset.  */
	      slotinfo[cnt].map->l_tls_offset = off;
	      continue;
	    }
	}

      off = roundup (offset + slotinfo[cnt].map->l_tls_blocksize - firstbyte,
		     slotinfo[cnt].map->l_tls_align) + firstbyte;
      if (off > offset + slotinfo[cnt].map->l_tls_blocksize
		+ (freebottom - freetop))
	{
	  freetop = offset;
	  freebottom = off - slotinfo[cnt].map->l_tls_blocksize;
	}
      offset = off;

      /* XXX For some architectures we perhaps should store the
	 negative offset.  */
      slotinfo[cnt].map->l_tls_offset = off;
    }

  GL(dl_tls_static_used) = offset;
  GL(dl_tls_static_size) = (roundup (offset + TLS_STATIC_SURPLUS, max_align)
			    + TLS_TCB_SIZE);
#elif TLS_DTV_AT_TP
  /* The TLS blocks start right after the TCB.  */
  size_t offset = TLS_TCB_SIZE;

  for (size_t cnt = 0; slotinfo[cnt].map != NULL; ++cnt)
    {
      assert (cnt < GL(dl_tls_dtv_slotinfo_list)->len);

      size_t firstbyte = (-slotinfo[cnt].map->l_tls_firstbyte_offset
			  & (slotinfo[cnt].map->l_tls_align - 1));
      size_t off;
      max_align = MAX (max_align, slotinfo[cnt].map->l_tls_align);

      if (slotinfo[cnt].map->l_tls_blocksize <= freetop - freebottom)
	{
	  off = roundup (freebottom, slotinfo[cnt].map->l_tls_align);
	  if (off - freebottom < firstbyte)
	    off += slotinfo[cnt].map->l_tls_align;
	  if (off + slotinfo[cnt].map->l_tls_blocksize - firstbyte <= freetop)
	    {
	      slotinfo[cnt].map->l_tls_offset = off - firstbyte;
	      freebottom = (off + slotinfo[cnt].map->l_tls_blocksize
			    - firstbyte);
	      continue;
	    }
	}

      off = roundup (offset, slotinfo[cnt].map->l_tls_align);
      if (off - offset < firstbyte)
	off += slotinfo[cnt].map->l_tls_align;

      slotinfo[cnt].map->l_tls_offset = off - firstbyte;
      if (off - firstbyte - offset > freetop - freebottom)
	{
	  freebottom = offset;
	  freetop = off - firstbyte;
	}

      offset = off + slotinfo[cnt].map->l_tls_blocksize - firstbyte;
    }

  GL(dl_tls_static_used) = offset;
  GL(dl_tls_static_size) = roundup (offset + TLS_STATIC_SURPLUS,
				    TLS_TCB_ALIGN);
#else
# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
#endif

  /* The alignment requirement for the static TLS block.  */
  GL(dl_tls_static_align) = max_align;
}


/* This is called only when the data structure setup was skipped at startup,
   when there was no need for it then.  Now we have dynamically loaded
   something needing TLS, or libpthread needs it.  */
int
internal_function
_dl_tls_setup (void)
{
  assert (GL(dl_tls_dtv_slotinfo_list) == NULL);
  assert (GL(dl_tls_max_dtv_idx) == 0);

  const size_t nelem = 2 + TLS_SLOTINFO_SURPLUS;

  GL(dl_tls_dtv_slotinfo_list)
    = calloc (1, (sizeof (struct dtv_slotinfo_list)
		  + nelem * sizeof (struct dtv_slotinfo)));
  if (GL(dl_tls_dtv_slotinfo_list) == NULL)
    return -1;

  GL(dl_tls_dtv_slotinfo_list)->len = nelem;

  /* Number of elements in the static TLS block.  It can't be zero
     because of various assumptions.  The one element is null.  */
  GL(dl_tls_static_nelem) = GL(dl_tls_max_dtv_idx) = 1;

  /* This initializes more variables for us.  */
  _dl_determine_tlsoffset ();

  return 0;
}
rtld_hidden_def (_dl_tls_setup)
#endif

static void *
internal_function
allocate_dtv (void *result)
{
  dtv_t *dtv;
  size_t dtv_length;

  /* We allocate a few more elements in the dtv than are needed for the
     initial set of modules.  This should avoid in most cases expansions
     of the dtv.  */
  dtv_length = GL(dl_tls_max_dtv_idx) + DTV_SURPLUS;
  dtv = calloc (dtv_length + 2, sizeof (dtv_t));
  if (dtv != NULL)
    {
      /* This is the initial length of the dtv.  */
      dtv[0].counter = dtv_length;

      /* The rest of the dtv (including the generation counter) is
	 Initialize with zero to indicate nothing there.  */

      /* Add the dtv to the thread data structures.  */
      INSTALL_DTV (result, dtv);
    }
  else
    result = NULL;

  return result;
}


/* Get size and alignment requirements of the static TLS block.  */
void
internal_function
_dl_get_tls_static_info (size_t *sizep, size_t *alignp)
{
  *sizep = GL(dl_tls_static_size);
  *alignp = GL(dl_tls_static_align);
}


void *
internal_function
_dl_allocate_tls_storage (void)
{
  void *result;
  size_t size = GL(dl_tls_static_size);

#if TLS_DTV_AT_TP
  /* Memory layout is:
     [ TLS_PRE_TCB_SIZE ] [ TLS_TCB_SIZE ] [ TLS blocks ]
			  ^ This should be returned.  */
  size += (TLS_PRE_TCB_SIZE + GL(dl_tls_static_align) - 1)
	  & ~(GL(dl_tls_static_align) - 1);
#endif

  /* Allocate a correctly aligned chunk of memory.  */
  result = __libc_memalign (GL(dl_tls_static_align), size);
  if (__builtin_expect (result != NULL, 1))
    {
      /* Allocate the DTV.  */
      void *allocated = result;

#if TLS_TCB_AT_TP
      /* The TCB follows the TLS blocks.  */
      result = (char *) result + size - TLS_TCB_SIZE;

      /* Clear the TCB data structure.  We can't ask the caller (i.e.
	 libpthread) to do it, because we will initialize the DTV et al.  */
      memset (result, '\0', TLS_TCB_SIZE);
#elif TLS_DTV_AT_TP
      result = (char *) result + size - GL(dl_tls_static_size);

      /* Clear the TCB data structure and TLS_PRE_TCB_SIZE bytes before it.
	 We can't ask the caller (i.e. libpthread) to do it, because we will
	 initialize the DTV et al.  */
      memset ((char *) result - TLS_PRE_TCB_SIZE, '\0',
	      TLS_PRE_TCB_SIZE + TLS_TCB_SIZE);
#endif

      result = allocate_dtv (result);
      if (result == NULL)
	free (allocated);
    }

  return result;
}


void *
internal_function
_dl_allocate_tls_init (void *result)
{
  if (result == NULL)
    /* The memory allocation failed.  */
    return NULL;

  dtv_t *dtv = GET_DTV (result);
  struct dtv_slotinfo_list *listp;
  size_t total = 0;
  size_t maxgen = 0;

  /* We have to prepare the dtv for all currently loaded modules using
     TLS.  For those which are dynamically loaded we add the values
     indicating deferred allocation.  */
  listp = GL(dl_tls_dtv_slotinfo_list);
  while (1)
    {
      size_t cnt;

      for (cnt = total == 0 ? 1 : 0; cnt < listp->len; ++cnt)
	{
	  struct link_map *map;
	  void *dest;

	  /* Check for the total number of used slots.  */
	  if (total + cnt > GL(dl_tls_max_dtv_idx))
	    break;

	  map = listp->slotinfo[cnt].map;
	  if (map == NULL)
	    /* Unused entry.  */
	    continue;

	  /* Keep track of the maximum generation number.  This might
	     not be the generation counter.  */
	  maxgen = MAX (maxgen, listp->slotinfo[cnt].gen);

	  if (map->l_tls_offset == NO_TLS_OFFSET
	      || map->l_tls_offset == FORCED_DYNAMIC_TLS_OFFSET)
	    {
	      /* For dynamically loaded modules we simply store
		 the value indicating deferred allocation.  */
	      dtv[map->l_tls_modid].pointer.val = TLS_DTV_UNALLOCATED;
	      dtv[map->l_tls_modid].pointer.is_static = false;
	      continue;
	    }

	  assert (map->l_tls_modid == cnt);
	  assert (map->l_tls_blocksize >= map->l_tls_initimage_size);
#if TLS_TCB_AT_TP
	  assert ((size_t) map->l_tls_offset >= map->l_tls_blocksize);
	  dest = (char *) result - map->l_tls_offset;
#elif TLS_DTV_AT_TP
	  dest = (char *) result + map->l_tls_offset;
#else
# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
#endif

	  /* Copy the initialization image and clear the BSS part.  */
	  dtv[map->l_tls_modid].pointer.val = dest;
	  dtv[map->l_tls_modid].pointer.is_static = true;
	  memset (__mempcpy (dest, map->l_tls_initimage,
			     map->l_tls_initimage_size), '\0',
		  map->l_tls_blocksize - map->l_tls_initimage_size);
	}

      total += cnt;
      if (total >= GL(dl_tls_max_dtv_idx))
	break;

      listp = listp->next;
      assert (listp != NULL);
    }

  /* The DTV version is up-to-date now.  */
  dtv[0].counter = maxgen;

  return result;
}
rtld_hidden_def (_dl_allocate_tls_init)

void *
internal_function
_dl_allocate_tls (void *mem)
{
  return _dl_allocate_tls_init (mem == NULL
				? _dl_allocate_tls_storage ()
				: allocate_dtv (mem));
}
rtld_hidden_def (_dl_allocate_tls)


void
internal_function
_dl_deallocate_tls (void *tcb, bool dealloc_tcb)
{
  dtv_t *dtv = GET_DTV (tcb);

  /* We need to free the memory allocated for non-static TLS.  */
  for (size_t cnt = 0; cnt < dtv[-1].counter; ++cnt)
    if (! dtv[1 + cnt].pointer.is_static
	&& dtv[1 + cnt].pointer.val != TLS_DTV_UNALLOCATED)
      free (dtv[1 + cnt].pointer.val);

  /* The array starts with dtv[-1].  */
#ifdef SHARED
  if (dtv != GL(dl_initial_dtv))
#endif
    free (dtv - 1);

  if (dealloc_tcb)
    {
#if TLS_TCB_AT_TP
      /* The TCB follows the TLS blocks.  Back up to free the whole block.  */
      tcb -= GL(dl_tls_static_size) - TLS_TCB_SIZE;
#elif TLS_DTV_AT_TP
      /* Back up the TLS_PRE_TCB_SIZE bytes.  */
      tcb -= (TLS_PRE_TCB_SIZE + GL(dl_tls_static_align) - 1)
	     & ~(GL(dl_tls_static_align) - 1);
#endif
      free (tcb);
    }
}
rtld_hidden_def (_dl_deallocate_tls)


#ifdef SHARED
/* The __tls_get_addr function has two basic forms which differ in the
   arguments.  The IA-64 form takes two parameters, the module ID and
   offset.  The form used, among others, on IA-32 takes a reference to
   a special structure which contain the same information.  The second
   form seems to be more often used (in the moment) so we default to
   it.  Users of the IA-64 form have to provide adequate definitions
   of the following macros.  */
# ifndef GET_ADDR_ARGS
#  define GET_ADDR_ARGS tls_index *ti
# endif
# ifndef GET_ADDR_MODULE
#  define GET_ADDR_MODULE ti->ti_module
# endif
# ifndef GET_ADDR_OFFSET
#  define GET_ADDR_OFFSET ti->ti_offset
# endif


static void *
allocate_and_init (struct link_map *map)
{
  void *newp;

  newp = __libc_memalign (map->l_tls_align, map->l_tls_blocksize);
  if (newp == NULL)
    oom ();

  /* Initialize the memory.  */
  memset (__mempcpy (newp, map->l_tls_initimage, map->l_tls_initimage_size),
	  '\0', map->l_tls_blocksize - map->l_tls_initimage_size);

  return newp;
}


struct link_map *
_dl_update_slotinfo (unsigned long int req_modid)
{
  struct link_map *the_map = NULL;
  dtv_t *dtv = THREAD_DTV ();

  /* The global dl_tls_dtv_slotinfo array contains for each module
     index the generation counter current when the entry was created.
     This array never shrinks so that all module indices which were
     valid at some time can be used to access it.  Before the first
     use of a new module index in this function the array was extended
     appropriately.  Access also does not have to be guarded against
     modifications of the array.  It is assumed that pointer-size
     values can be read atomically even in SMP environments.  It is
     possible that other threads at the same time dynamically load
     code and therefore add to the slotinfo list.  This is a problem
     since we must not pick up any information about incomplete work.
     The solution to this is to ignore all dtv slots which were
     created after the one we are currently interested.  We know that
     dynamic loading for this module is completed and this is the last
     load operation we know finished.  */
  unsigned long int idx = req_modid;
  struct dtv_slotinfo_list *listp = GL(dl_tls_dtv_slotinfo_list);

  while (idx >= listp->len)
    {
      idx -= listp->len;
      listp = listp->next;
    }

  if (dtv[0].counter < listp->slotinfo[idx].gen)
    {
      /* The generation counter for the slot is higher than what the
	 current dtv implements.  We have to update the whole dtv but
	 only those entries with a generation counter <= the one for
	 the entry we need.  */
      size_t new_gen = listp->slotinfo[idx].gen;
      size_t total = 0;

      /* We have to look through the entire dtv slotinfo list.  */
      listp =  GL(dl_tls_dtv_slotinfo_list);
      do
	{
	  for (size_t cnt = total == 0 ? 1 : 0; cnt < listp->len; ++cnt)
	    {
	      size_t gen = listp->slotinfo[cnt].gen;

	      if (gen > new_gen)
		/* This is a slot for a generation younger than the
		   one we are handling now.  It might be incompletely
		   set up so ignore it.  */
		continue;

	      /* If the entry is older than the current dtv layout we
		 know we don't have to handle it.  */
	      if (gen <= dtv[0].counter)
		continue;

	      /* If there is no map this means the entry is empty.  */
	      struct link_map *map = listp->slotinfo[cnt].map;
	      if (map == NULL)
		{
		  /* If this modid was used at some point the memory
		     might still be allocated.  */
		  if (! dtv[total + cnt].pointer.is_static
		      && dtv[total + cnt].pointer.val != TLS_DTV_UNALLOCATED)
		    {
		      free (dtv[total + cnt].pointer.val);
		      dtv[total + cnt].pointer.val = TLS_DTV_UNALLOCATED;
		    }

		  continue;
		}

	      /* Check whether the current dtv array is large enough.  */
	      size_t modid = map->l_tls_modid;
	      assert (total + cnt == modid);
	      if (dtv[-1].counter < modid)
		{
		  /* Reallocate the dtv.  */
		  dtv_t *newp;
		  size_t newsize = GL(dl_tls_max_dtv_idx) + DTV_SURPLUS;
		  size_t oldsize = dtv[-1].counter;

		  assert (map->l_tls_modid <= newsize);

		  if (dtv == GL(dl_initial_dtv))
		    {
		      /* This is the initial dtv that was allocated
			 during rtld startup using the dl-minimal.c
			 malloc instead of the real malloc.  We can't
			 free it, we have to abandon the old storage.  */

		      newp = malloc ((2 + newsize) * sizeof (dtv_t));
		      if (newp == NULL)
			oom ();
		      memcpy (newp, &dtv[-1], (2 + oldsize) * sizeof (dtv_t));
		    }
		  else
		    {
		      newp = realloc (&dtv[-1],
				      (2 + newsize) * sizeof (dtv_t));
		      if (newp == NULL)
			oom ();
		    }

		  newp[0].counter = newsize;

		  /* Clear the newly allocated part.  */
		  memset (newp + 2 + oldsize, '\0',
			  (newsize - oldsize) * sizeof (dtv_t));

		  /* Point dtv to the generation counter.  */
		  dtv = &newp[1];

		  /* Install this new dtv in the thread data
		     structures.  */
		  INSTALL_NEW_DTV (dtv);
		}

	      /* If there is currently memory allocate for this
		 dtv entry free it.  */
	      /* XXX Ideally we will at some point create a memory
		 pool.  */
	      if (! dtv[modid].pointer.is_static
		  && dtv[modid].pointer.val != TLS_DTV_UNALLOCATED)
		/* Note that free is called for NULL is well.  We
		   deallocate even if it is this dtv entry we are
		   supposed to load.  The reason is that we call
		   memalign and not malloc.  */
		free (dtv[modid].pointer.val);

	      /* This module is loaded dynamically- We defer memory
		 allocation.  */
	      dtv[modid].pointer.is_static = false;
	      dtv[modid].pointer.val = TLS_DTV_UNALLOCATED;

	      if (modid == req_modid)
		the_map = map;
	    }

	  total += listp->len;
	}
      while ((listp = listp->next) != NULL);

      /* This will be the new maximum generation counter.  */
      dtv[0].counter = new_gen;
    }

  return the_map;
}


static void *
__attribute_noinline__
tls_get_addr_tail (dtv_t *dtv, struct link_map *the_map, size_t module)
{
  /* The allocation was deferred.  Do it now.  */
  if (the_map == NULL)
    {
      /* Find the link map for this module.  */
      size_t idx = module;
      struct dtv_slotinfo_list *listp = GL(dl_tls_dtv_slotinfo_list);

      while (idx >= listp->len)
	{
	  idx -= listp->len;
	  listp = listp->next;
	}

      the_map = listp->slotinfo[idx].map;
    }

 again:
  /* Make sure that, if a dlopen running in parallel forces the
     variable into static storage, we'll wait until the address in the
     static TLS block is set up, and use that.  If we're undecided
     yet, make sure we make the decision holding the lock as well.  */
  if (__builtin_expect (the_map->l_tls_offset
			!= FORCED_DYNAMIC_TLS_OFFSET, 0))
    {
      __rtld_lock_lock_recursive (GL(dl_load_lock));
      if (__builtin_expect (the_map->l_tls_offset == NO_TLS_OFFSET, 1))
	{
	  the_map->l_tls_offset = FORCED_DYNAMIC_TLS_OFFSET;
	  __rtld_lock_unlock_recursive (GL(dl_load_lock));
	}
      else
	{
	  __rtld_lock_unlock_recursive (GL(dl_load_lock));
	  if (__builtin_expect (the_map->l_tls_offset
				!= FORCED_DYNAMIC_TLS_OFFSET, 1))
	    {
	      void *p = dtv[module].pointer.val;
	      if (__builtin_expect (p == TLS_DTV_UNALLOCATED, 0))
		goto again;

	      return p;
	    }
	}
    }
  void *p = dtv[module].pointer.val = allocate_and_init (the_map);
  dtv[module].pointer.is_static = false;

  return p;
}


/* The generic dynamic and local dynamic model cannot be used in
   statically linked applications.  */
void *
__tls_get_addr (GET_ADDR_ARGS)
{
  dtv_t *dtv = THREAD_DTV ();
  struct link_map *the_map = NULL;
  void *p;

  if (__builtin_expect (dtv[0].counter != GL(dl_tls_generation), 0))
    the_map = _dl_update_slotinfo (GET_ADDR_MODULE);

  p = dtv[GET_ADDR_MODULE].pointer.val;

  if (__builtin_expect (p == TLS_DTV_UNALLOCATED, 0))
    p = tls_get_addr_tail (dtv, the_map, GET_ADDR_MODULE);

  return (char *) p + GET_ADDR_OFFSET;
}
#endif


/* Look up the module's TLS block as for __tls_get_addr,
   but never touch anything.  Return null if it's not allocated yet.  */
void *
_dl_tls_get_addr_soft (struct link_map *l)
{
  if (__builtin_expect (l->l_tls_modid == 0, 0))
    /* This module has no TLS segment.  */
    return NULL;

  dtv_t *dtv = THREAD_DTV ();
  if (__builtin_expect (dtv[0].counter != GL(dl_tls_generation), 0))
    {
      /* This thread's DTV is not completely current,
	 but it might already cover this module.  */

      if (l->l_tls_modid >= dtv[-1].counter)
	/* Nope.  */
	return NULL;

      size_t idx = l->l_tls_modid;
      struct dtv_slotinfo_list *listp = GL(dl_tls_dtv_slotinfo_list);
      while (idx >= listp->len)
	{
	  idx -= listp->len;
	  listp = listp->next;
	}

      /* We've reached the slot for this module.
	 If its generation counter is higher than the DTV's,
	 this thread does not know about this module yet.  */
      if (dtv[0].counter < listp->slotinfo[idx].gen)
	return NULL;
    }

  void *data = dtv[l->l_tls_modid].pointer.val;
  if (__builtin_expect (data == TLS_DTV_UNALLOCATED, 0))
    /* The DTV is current, but this thread has not yet needed
       to allocate this module's segment.  */
    data = NULL;

  return data;
}


void
_dl_add_to_slotinfo (struct link_map *l)
{
  /* Now that we know the object is loaded successfully add
     modules containing TLS data to the dtv info table.  We
     might have to increase its size.  */
  struct dtv_slotinfo_list *listp;
  struct dtv_slotinfo_list *prevp;
  size_t idx = l->l_tls_modid;

  /* Find the place in the dtv slotinfo list.  */
  listp = GL(dl_tls_dtv_slotinfo_list);
  prevp = NULL;		/* Needed to shut up gcc.  */
  do
    {
      /* Does it fit in the array of this list element?  */
      if (idx < listp->len)
	break;
      idx -= listp->len;
      prevp = listp;
      listp = listp->next;
    }
  while (listp != NULL);

  if (listp == NULL)
    {
      /* When we come here it means we have to add a new element
	 to the slotinfo list.  And the new module must be in
	 the first slot.  */
      assert (idx == 0);

      listp = prevp->next = (struct dtv_slotinfo_list *)
	malloc (sizeof (struct dtv_slotinfo_list)
		+ TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
      if (listp == NULL)
	{
	  /* We ran out of memory.  We will simply fail this
	     call but don't undo anything we did so far.  The
	     application will crash or be terminated anyway very
	     soon.  */

	  /* We have to do this since some entries in the dtv
	     slotinfo array might already point to this
	     generation.  */
	  ++GL(dl_tls_generation);

	  _dl_signal_error (ENOMEM, "dlopen", NULL, N_("\
cannot create TLS data structures"));
	}

      listp->len = TLS_SLOTINFO_SURPLUS;
      listp->next = NULL;
      memset (listp->slotinfo, '\0',
	      TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
    }

  /* Add the information into the slotinfo data structure.  */
  listp->slotinfo[idx].map = l;
  listp->slotinfo[idx].gen = GL(dl_tls_generation) + 1;
}