summaryrefslogtreecommitdiff
path: root/include/libc-symbols.h
blob: 18f26b2e61af72dcdaed5d8f524d4845d844f311 (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
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
/* Support macros for making weak and strong aliases for symbols,
   and for using symbol sets and linker warnings with GNU ld.
   Copyright (C) 1995-2017 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, see
   <http://www.gnu.org/licenses/>.  */

#ifndef _LIBC_SYMBOLS_H
#define _LIBC_SYMBOLS_H	1

#define IN_MODULE PASTE_NAME (MODULE_, MODULE_NAME)
#define IS_IN(lib) (IN_MODULE == MODULE_##lib)

/* Returns true if the current module is a versioned library.  Versioned
   library names culled from shlib-versions files are assigned a MODULE_*
   value lower than MODULE_LIBS_BEGIN.  */
#define IS_IN_LIB (IN_MODULE > MODULE_LIBS_BEGIN)

#define PASTE_NAME(a,b)      PASTE_NAME1 (a,b)
#define PASTE_NAME1(a,b)     a##b

/* This file's macros are included implicitly in the compilation of every
   file in the C library by -imacros.

   We include config.h which is generated by configure.
   It should define for us the following symbol:

   * HAVE_ASM_SET_DIRECTIVE if we have `.set B, A' instead of `A = B'.

   */

/* This is defined for the compilation of all C library code.  features.h
   tests this to avoid inclusion of stubs.h while compiling the library,
   before stubs.h has been generated.  Some library code that is shared
   with other packages also tests this symbol to see if it is being
   compiled as part of the C library.  We must define this before including
   config.h, because it makes some definitions conditional on whether libc
   itself is being compiled, or just some generator program.  */
#define _LIBC	1

/* Enable declarations of GNU extensions, since we are compiling them.  */
#define _GNU_SOURCE	1

#include <config.h>

/* Define this for the benefit of portable GNU code that wants to check it.
   Code that checks with #if will not #include <config.h> again, since we've
   already done it (and this file is implicitly included in every compile,
   via -include).  Code that checks with #ifdef will #include <config.h>,
   but that file should always be idempotent (i.e., it's just #define/#undef
   and nothing else anywhere should be changing the macro state it touches),
   so it's harmless.  */
#define HAVE_CONFIG_H	0

/* Define these macros for the benefit of portable GNU code that wants to check
   them.  Of course, STDC_HEADERS is never false when building libc!  */
#define STDC_HEADERS	1
#define HAVE_MBSTATE_T	1
#define HAVE_MBSRTOWCS	1
#define HAVE_LIBINTL_H	1
#define HAVE_WCTYPE_H	1
#define HAVE_ISWCTYPE	1
#define ENABLE_NLS	1

/* The symbols in all the user (non-_) macros are C symbols.  */

#ifndef __SYMBOL_PREFIX
# define __SYMBOL_PREFIX
#endif

#ifndef C_SYMBOL_NAME
# define C_SYMBOL_NAME(name) name
#endif

#ifndef ASM_LINE_SEP
# define ASM_LINE_SEP ;
#endif

#ifndef __ASSEMBLER__
/* GCC understands weak symbols and aliases; use its interface where
   possible, instead of embedded assembly language.  */

/* Define ALIASNAME as a strong alias for NAME.  */
# define strong_alias(name, aliasname) _strong_alias(name, aliasname)
# define _strong_alias(name, aliasname) \
  extern __typeof (name) aliasname __attribute__ ((alias (#name)));

/* This comes between the return type and function name in
   a function definition to make that definition weak.  */
# define weak_function __attribute__ ((weak))
# define weak_const_function __attribute__ ((weak, __const__))

/* Define ALIASNAME as a weak alias for NAME.
   If weak aliases are not available, this defines a strong alias.  */
# define weak_alias(name, aliasname) _weak_alias (name, aliasname)
# define _weak_alias(name, aliasname) \
  extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));

/* Same as WEAK_ALIAS, but mark symbol as hidden.  */
# define weak_hidden_alias(name, aliasname) \
  _weak_hidden_alias (name, aliasname)
# define _weak_hidden_alias(name, aliasname) \
  extern __typeof (name) aliasname \
    __attribute__ ((weak, alias (#name), __visibility__ ("hidden")));

/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined).  */
# define weak_extern(symbol) _weak_extern (weak symbol)
# define _weak_extern(expr) _Pragma (#expr)

/* In shared builds, the expression call_function_static_weak
   (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
   identifier) unconditionally, with the (potentially empty) argument
   list ARGUMENTS.  In static builds, if FUNCTION-SYMBOL has a
   definition, the function is invoked as before; if FUNCTION-SYMBOL
   is NULL, no call is performed.  */
# ifdef SHARED
#  define call_function_static_weak(func, ...) func (__VA_ARGS__)
# else	/* !SHARED */
#  define call_function_static_weak(func, ...)		\
  ({							\
    extern __typeof__ (func) func weak_function;	\
    (func != NULL ? func (__VA_ARGS__) : (void)0);	\
  })
# endif

#else /* __ASSEMBLER__ */

# ifdef HAVE_ASM_SET_DIRECTIVE
#  define strong_alias(original, alias)				\
  .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP		\
  .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
#  define strong_data_alias(original, alias) strong_alias(original, alias)
# else
#  define strong_alias(original, alias)				\
  .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP		\
  C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
#  define strong_data_alias(original, alias) strong_alias(original, alias)
# endif

# define weak_alias(original, alias)					\
  .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP				\
  C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)

# define weak_extern(symbol)						\
  .weak C_SYMBOL_NAME (symbol)

#endif /* __ASSEMBLER__ */

/* On some platforms we can make internal function calls (i.e., calls of
   functions not exported) a bit faster by using a different calling
   convention.  */
#ifndef internal_function
# define internal_function	/* empty */
#endif

/* Determine the return address.  */
#define RETURN_ADDRESS(nr) \
  __builtin_extract_return_addr (__builtin_return_address (nr))

/* When a reference to SYMBOL is encountered, the linker will emit a
   warning message MSG.  */
/* We want the .gnu.warning.SYMBOL section to be unallocated.  */
#define __make_section_unallocated(section_string)	\
  asm (".section " section_string "\n\t.previous");

/* Tacking on "\n\t#" to the section name makes gcc put it's bogus
   section attributes on what looks like a comment to the assembler.  */
#ifdef HAVE_SECTION_QUOTES
# define __sec_comment "\"\n\t#\""
#else
# define __sec_comment "\n\t#"
#endif
#define link_warning(symbol, msg) \
  __make_section_unallocated (".gnu.warning." #symbol) \
  static const char __evoke_link_warning_##symbol[]	\
    __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
    = msg;
#define libc_freeres_ptr(decl) \
  __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
  decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
#define __libc_freeres_fn_section \
  __attribute__ ((section ("__libc_freeres_fn")))

#define libc_freeres_fn(name)	\
  static void name (void) __attribute_used__ __libc_freeres_fn_section;	\
  text_set_element (__libc_subfreeres, name);				\
  static void name (void)

/* A canned warning for sysdeps/stub functions.  */
#define	stub_warning(name) \
  __make_section_unallocated (".gnu.glibc-stub." #name) \
  link_warning (name, #name " is not implemented and will always fail")

/* Warning for linking functions calling dlopen into static binaries.  */
#ifdef SHARED
#define static_link_warning(name)
#else
#define static_link_warning(name) static_link_warning1(name)
#define static_link_warning1(name) \
  link_warning(name, "Using '" #name "' in statically linked applications \
requires at runtime the shared libraries from the glibc version used \
for linking")
#endif

/* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
   alias to ORIGINAL, when the assembler supports such declarations
   (such as in ELF).
   This is only necessary when defining something in assembly, or playing
   funny alias games where the size should be other than what the compiler
   thinks it is.  */
#define declare_symbol_alias(symbol, original, type, size) \
  declare_symbol_alias_1 (symbol, original, type, size)
#ifdef __ASSEMBLER__
# define declare_symbol_alias_1(symbol, original, type, size) \
   strong_alias (original, symbol); \
   .type C_SYMBOL_NAME (symbol), %##type; \
   .size C_SYMBOL_NAME (symbol), size
#else /* Not __ASSEMBLER__.  */
# define declare_symbol_alias_1(symbol, original, type, size) \
   asm (".globl " __SYMBOL_PREFIX #symbol \
	"\n\t" declare_symbol_alias_1_alias (symbol, original) \
	"\n\t.type " __SYMBOL_PREFIX #symbol ", " \
	"%" #type \
	"\n\t.size " __SYMBOL_PREFIX #symbol ", " #size);
# ifdef HAVE_ASM_SET_DIRECTIVE
#  define declare_symbol_alias_1_alias(symbol, original) \
     ".set " __SYMBOL_PREFIX #symbol ", " __SYMBOL_PREFIX #original
# else
#  define declare_symbol_alias_1_alias(symbol, original) \
     __SYMBOL_PREFIX #symbol " = " __SYMBOL_PREFIX #original
# endif /* HAVE_ASM_SET_DIRECTIVE */
#endif /* __ASSEMBLER__ */


/*

*/

/* Symbol set support macros.  */

/* Make SYMBOL, which is in the text segment, an element of SET.  */
#define text_set_element(set, symbol)	_elf_set_element(set, symbol)
/* Make SYMBOL, which is in the data segment, an element of SET.  */
#define data_set_element(set, symbol)	_elf_set_element(set, symbol)
/* Make SYMBOL, which is in the bss segment, an element of SET.  */
#define bss_set_element(set, symbol)	_elf_set_element(set, symbol)

/* These are all done the same way in ELF.
   There is a new section created for each set.  */
#ifdef SHARED
/* When building a shared library, make the set section writable,
   because it will need to be relocated at run time anyway.  */
# define _elf_set_element(set, symbol) \
  static const void *__elf_set_##set##_element_##symbol##__ \
    __attribute__ ((used, section (#set))) = &(symbol)
#else
# define _elf_set_element(set, symbol) \
  static const void *const __elf_set_##set##_element_##symbol##__ \
    __attribute__ ((used, section (#set))) = &(symbol)
#endif

/* Define SET as a symbol set.  This may be required (it is in a.out) to
   be able to use the set's contents.  */
#define symbol_set_define(set)	symbol_set_declare(set)

/* Declare SET for use in this module, if defined in another module.
   In a shared library, this is always local to that shared object.
   For static linking, the set might be wholly absent and so we use
   weak references.  */
#define symbol_set_declare(set) \
  extern char const __start_##set[] __symbol_set_attribute; \
  extern char const __stop_##set[] __symbol_set_attribute;
#ifdef SHARED
# define __symbol_set_attribute attribute_hidden
#else
# define __symbol_set_attribute __attribute__ ((weak))
#endif

/* Return a pointer (void *const *) to the first element of SET.  */
#define symbol_set_first_element(set)	((void *const *) (&__start_##set))

/* Return true iff PTR (a void *const *) has been incremented
   past the last element in SET.  */
#define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)

/* Use symbol_version_reference to specify the version a symbol
   reference should link to.  Use symbol_version or
   default_symbol_version for the definition of a versioned symbol.
   The difference is that the latter is a no-op in non-shared
   builds.  */
#ifdef __ASSEMBLER__
# define symbol_version_reference(real, name, version) \
     .symver real, name##@##version
#else  /* !__ASSEMBLER__ */
# define symbol_version_reference(real, name, version) \
  __asm__ (".symver " #real "," #name "@" #version)
#endif

#ifdef SHARED
# define symbol_version(real, name, version) \
  symbol_version_reference(real, name, version)
# define default_symbol_version(real, name, version) \
     _default_symbol_version(real, name, version)
# ifdef __ASSEMBLER__
#  define _default_symbol_version(real, name, version) \
     .symver real, name##@##@##version
# else
#  define _default_symbol_version(real, name, version) \
     __asm__ (".symver " #real "," #name "@@" #version)
# endif
#else
# define symbol_version(real, name, version)
# define default_symbol_version(real, name, version) \
  strong_alias(real, name)
#endif

#if defined SHARED || defined LIBC_NONSHARED
# define attribute_hidden __attribute__ ((visibility ("hidden")))
#else
# define attribute_hidden
#endif

#define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))

#define attribute_relro __attribute__ ((section (".data.rel.ro")))


/* Used to disable stack protection in sensitive places, like ifunc
   resolvers and early static TLS init.  */
#ifdef HAVE_CC_NO_STACK_PROTECTOR
# define inhibit_stack_protector \
    __attribute__ ((__optimize__ ("-fno-stack-protector")))
#else
# define inhibit_stack_protector
#endif

/* The following macros are used for PLT bypassing within libc.so
   (and if needed other libraries similarly).
   First of all, you need to have the function prototyped somewhere,
   say in foo/foo.h:

   int foo (int __bar);

   If calls to foo within libc.so should always go to foo defined in libc.so,
   then in include/foo.h you add:

   libc_hidden_proto (foo)

   line and after the foo function definition:

   int foo (int __bar)
   {
     return __bar;
   }
   libc_hidden_def (foo)

   or

   int foo (int __bar)
   {
     return __bar;
   }
   libc_hidden_weak (foo)

   Similarly for global data.  If references to foo within libc.so should
   always go to foo defined in libc.so, then in include/foo.h you add:

   libc_hidden_proto (foo)

   line and after foo's definition:

   int foo = INITIAL_FOO_VALUE;
   libc_hidden_data_def (foo)

   or

   int foo = INITIAL_FOO_VALUE;
   libc_hidden_data_weak (foo)

   If foo is normally just an alias (strong or weak) to some other function,
   you should use the normal strong_alias first, then add libc_hidden_def
   or libc_hidden_weak:

   int baz (int __bar)
   {
     return __bar;
   }
   strong_alias (baz, foo)
   libc_hidden_weak (foo)

   If the function should be internal to multiple objects, say ld.so and
   libc.so, the best way is to use:

   #if IS_IN (libc) || IS_IN (rtld)
   hidden_proto (foo)
   #endif

   in include/foo.h and the normal macros at all function definitions
   depending on what DSO they belong to.

   If versioned_symbol macro is used to define foo,
   libc_hidden_ver macro should be used, as in:

   int __real_foo (int __bar)
   {
     return __bar;
   }
   versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
   libc_hidden_ver (__real_foo, foo)  */

#if defined SHARED && !defined NO_HIDDEN
# ifndef __ASSEMBLER__
#  define __hidden_proto_hiddenattr(attrs...) \
  __attribute__ ((visibility ("hidden"), ##attrs))
#  define hidden_proto(name, attrs...) \
  __hidden_proto (name, , __GI_##name, ##attrs)
#  define hidden_tls_proto(name, attrs...) \
  __hidden_proto (name, __thread, __GI_##name, ##attrs)
#  define __hidden_proto(name, thread, internal, attrs...)	     \
  extern thread __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
  __hidden_proto_hiddenattr (attrs);
#  define __hidden_asmname(name) \
  __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
#  define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
#  define __hidden_asmname2(prefix, name) #prefix name
#  define __hidden_ver1(local, internal, name) \
  extern __typeof (name) __EI_##name __asm__(__hidden_asmname (#internal)); \
  extern __typeof (name) __EI_##name \
	__attribute__((alias (__hidden_asmname (#local))))
#  define hidden_ver(local, name)	__hidden_ver1(local, __GI_##name, name);
#  define hidden_data_ver(local, name)	hidden_ver(local, name)
#  define hidden_def(name)		__hidden_ver1(__GI_##name, name, name);
#  define hidden_data_def(name)		hidden_def(name)
#  define hidden_weak(name) \
	__hidden_ver1(__GI_##name, name, name) __attribute__((weak));
#  define hidden_data_weak(name)	hidden_weak(name)
#  define hidden_nolink(name, lib, version) \
  __hidden_nolink1 (__GI_##name, __EI_##name, name, VERSION_##lib##_##version)
#  define __hidden_nolink1(local, internal, name, version) \
  __hidden_nolink2 (local, internal, name, version)
#  define __hidden_nolink2(local, internal, name, version) \
  extern __typeof (name) internal __attribute__ ((alias (#local))); \
  __hidden_nolink3 (local, internal, #name "@" #version)
#  define __hidden_nolink3(local, internal, vername) \
  __asm__ (".symver " #internal ", " vername);
# else
/* For assembly, we need to do the opposite of what we do in C:
   in assembly gcc __REDIRECT stuff is not in place, so functions
   are defined by its normal name and we need to create the
   __GI_* alias to it, in C __REDIRECT causes the function definition
   to use __GI_* name and we need to add alias to the real name.
   There is no reason to use hidden_weak over hidden_def in assembly,
   but we provide it for consistency with the C usage.
   hidden_proto doesn't make sense for assembly but the equivalent
   is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET.  */
#  define hidden_def(name)	strong_alias (name, __GI_##name)
#  define hidden_weak(name)	hidden_def (name)
#  define hidden_ver(local, name) strong_alias (local, __GI_##name)
#  define hidden_data_def(name)	strong_data_alias (name, __GI_##name)
#  define hidden_data_weak(name)	hidden_data_def (name)
#  define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
#  define HIDDEN_JUMPTARGET(name) __GI_##name
# endif
#else
# ifndef __ASSEMBLER__
#  define hidden_proto(name, attrs...)
#  define hidden_tls_proto(name, attrs...)
# else
#  define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
# endif /* Not  __ASSEMBLER__ */
# define hidden_weak(name)
# define hidden_def(name)
# define hidden_ver(local, name)
# define hidden_data_weak(name)
# define hidden_data_def(name)
# define hidden_data_ver(local, name)
# define hidden_nolink(name, lib, version)
#endif

#if IS_IN (libc)
# define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
# define libc_hidden_def(name) hidden_def (name)
# define libc_hidden_weak(name) hidden_weak (name)
# ifdef LINK_OBSOLETE_RPC
   /* libc_hidden_nolink_sunrpc should only get used in sunrpc code.  */
#  define libc_hidden_nolink_sunrpc(name, version) hidden_def (name)
# else
#  define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
# endif
# define libc_hidden_ver(local, name) hidden_ver (local, name)
# define libc_hidden_data_def(name) hidden_data_def (name)
# define libc_hidden_data_weak(name) hidden_data_weak (name)
# define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libc_hidden_proto(name, attrs...)
# define libc_hidden_tls_proto(name, attrs...)
# define libc_hidden_def(name)
# define libc_hidden_weak(name)
# define libc_hidden_ver(local, name)
# define libc_hidden_data_def(name)
# define libc_hidden_data_weak(name)
# define libc_hidden_data_ver(local, name)
#endif

#if IS_IN (rtld)
# define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
# define rtld_hidden_def(name) hidden_def (name)
# define rtld_hidden_weak(name) hidden_weak (name)
# define rtld_hidden_ver(local, name) hidden_ver (local, name)
# define rtld_hidden_data_def(name) hidden_data_def (name)
# define rtld_hidden_data_weak(name) hidden_data_weak (name)
# define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define rtld_hidden_proto(name, attrs...)
# define rtld_hidden_tls_proto(name, attrs...)
# define rtld_hidden_def(name)
# define rtld_hidden_weak(name)
# define rtld_hidden_ver(local, name)
# define rtld_hidden_data_def(name)
# define rtld_hidden_data_weak(name)
# define rtld_hidden_data_ver(local, name)
#endif

#if IS_IN (libm)
# define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libm_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
# define libm_hidden_def(name) hidden_def (name)
# define libm_hidden_weak(name) hidden_weak (name)
# define libm_hidden_ver(local, name) hidden_ver (local, name)
# define libm_hidden_data_def(name) hidden_data_def (name)
# define libm_hidden_data_weak(name) hidden_data_weak (name)
# define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libm_hidden_proto(name, attrs...)
# define libm_hidden_tls_proto(name, attrs...)
# define libm_hidden_def(name)
# define libm_hidden_weak(name)
# define libm_hidden_ver(local, name)
# define libm_hidden_data_def(name)
# define libm_hidden_data_weak(name)
# define libm_hidden_data_ver(local, name)
#endif

#if IS_IN (libmvec)
# define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libmvec_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
# define libmvec_hidden_def(name) hidden_def (name)
# define libmvec_hidden_weak(name) hidden_weak (name)
# define libmvec_hidden_ver(local, name) hidden_ver (local, name)
# define libmvec_hidden_data_def(name) hidden_data_def (name)
# define libmvec_hidden_data_weak(name) hidden_data_weak (name)
# define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libmvec_hidden_proto(name, attrs...)
# define libmvec_hidden_tls_proto(name, attrs...)
# define libmvec_hidden_def(name)
# define libmvec_hidden_weak(name)
# define libmvec_hidden_ver(local, name)
# define libmvec_hidden_data_def(name)
# define libmvec_hidden_data_weak(name)
# define libmvec_hidden_data_ver(local, name)
#endif

#if IS_IN (libresolv)
# define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libresolv_hidden_tls_proto(name, attrs...) \
  hidden_tls_proto (name, ##attrs)
# define libresolv_hidden_def(name) hidden_def (name)
# define libresolv_hidden_weak(name) hidden_weak (name)
# define libresolv_hidden_ver(local, name) hidden_ver (local, name)
# define libresolv_hidden_data_def(name) hidden_data_def (name)
# define libresolv_hidden_data_weak(name) hidden_data_weak (name)
# define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libresolv_hidden_proto(name, attrs...)
# define libresolv_hidden_tls_proto(name, attrs...)
# define libresolv_hidden_def(name)
# define libresolv_hidden_weak(name)
# define libresolv_hidden_ver(local, name)
# define libresolv_hidden_data_def(name)
# define libresolv_hidden_data_weak(name)
# define libresolv_hidden_data_ver(local, name)
#endif

#if IS_IN (librt)
# define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define librt_hidden_tls_proto(name, attrs...) \
  hidden_tls_proto (name, ##attrs)
# define librt_hidden_def(name) hidden_def (name)
# define librt_hidden_weak(name) hidden_weak (name)
# define librt_hidden_ver(local, name) hidden_ver (local, name)
# define librt_hidden_data_def(name) hidden_data_def (name)
# define librt_hidden_data_weak(name) hidden_data_weak (name)
# define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define librt_hidden_proto(name, attrs...)
# define librt_hidden_tls_proto(name, attrs...)
# define librt_hidden_def(name)
# define librt_hidden_weak(name)
# define librt_hidden_ver(local, name)
# define librt_hidden_data_def(name)
# define librt_hidden_data_weak(name)
# define librt_hidden_data_ver(local, name)
#endif

#if IS_IN (libdl)
# define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libdl_hidden_tls_proto(name, attrs...) \
  hidden_tls_proto (name, ##attrs)
# define libdl_hidden_def(name) hidden_def (name)
# define libdl_hidden_weak(name) hidden_weak (name)
# define libdl_hidden_ver(local, name) hidden_ver (local, name)
# define libdl_hidden_data_def(name) hidden_data_def (name)
# define libdl_hidden_data_weak(name) hidden_data_weak (name)
# define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libdl_hidden_proto(name, attrs...)
# define libdl_hidden_tls_proto(name, attrs...)
# define libdl_hidden_def(name)
# define libdl_hidden_weak(name)
# define libdl_hidden_ver(local, name)
# define libdl_hidden_data_def(name)
# define libdl_hidden_data_weak(name)
# define libdl_hidden_data_ver(local, name)
#endif

#if IS_IN (libnss_files)
# define libnss_files_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libnss_files_hidden_tls_proto(name, attrs...) \
  hidden_tls_proto (name, ##attrs)
# define libnss_files_hidden_def(name) hidden_def (name)
# define libnss_files_hidden_weak(name) hidden_weak (name)
# define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
# define libnss_files_hidden_data_def(name) hidden_data_def (name)
# define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
# define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
#else
# define libnss_files_hidden_proto(name, attrs...)
# define libnss_files_hidden_tls_proto(name, attrs...)
# define libnss_files_hidden_def(name)
# define libnss_files_hidden_weak(name)
# define libnss_files_hidden_ver(local, name)
# define libnss_files_hidden_data_def(name)
# define libnss_files_hidden_data_weak(name)
# define libnss_files_hidden_data_ver(local, name)
#endif

#if IS_IN (libnsl)
# define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libnsl_hidden_tls_proto(name, attrs...) \
  hidden_tls_proto (name, ##attrs)
# ifdef LINK_OBSOLETE_NSL
   /* libnsl_hidden_nolink should only get used in libnsl code.  */
#  define libnsl_hidden_nolink_def(name, version) libnsl_hidden_def (name)
# else
#  define libnsl_hidden_nolink_def(name, version) hidden_nolink (name, libnsl, version)
# endif
# define libnsl_hidden_def(name) hidden_def (name)
# define libnsl_hidden_weak(name) hidden_weak (name)
# define libnsl_hidden_ver(local, name) hidden_ver (local, name)
# define libnsl_hidden_data_def(name) hidden_data_def (name)
# define libnsl_hidden_data_weak(name) hidden_data_weak (name)
# define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libnsl_hidden_proto(name, attrs...)
# define libnsl_hidden_tls_proto(name, attrs...)
# define libnsl_hidden_def(name)
# define libnsl_hidden_weak(name)
# define libnsl_hidden_ver(local, name)
# define libnsl_hidden_data_def(name)
# define libnsl_hidden_data_weak(name)
# define libnsl_hidden_data_ver(local, name)
#endif

#if IS_IN (libnss_nisplus)
# define libnss_nisplus_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libnss_nisplus_hidden_tls_proto(name, attrs...) \
  hidden_tls_proto (name, ##attrs)
# define libnss_nisplus_hidden_def(name) hidden_def (name)
# define libnss_nisplus_hidden_weak(name) hidden_weak (name)
# define libnss_nisplus_hidden_ver(local, name) hidden_ver (local, name)
# define libnss_nisplus_hidden_data_def(name) hidden_data_def (name)
# define libnss_nisplus_hidden_data_weak(name) hidden_data_weak (name)
# define libnss_nisplus_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libnss_nisplus_hidden_proto(name, attrs...)
# define libnss_nisplus_hidden_tls_proto(name, attrs...)
# define libnss_nisplus_hidden_def(name)
# define libnss_nisplus_hidden_weak(name)
# define libnss_nisplus_hidden_ver(local, name)
# define libnss_nisplus_hidden_data_def(name)
# define libnss_nisplus_hidden_data_weak(name)
# define libnss_nisplus_hidden_data_ver(local, name)
#endif

#define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
#define libc_hidden_builtin_def(name) libc_hidden_def (name)
#define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
#define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
#ifdef __ASSEMBLER__
# define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
#endif

#if IS_IN (libutil)
# define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libutil_hidden_tls_proto(name, attrs...) \
  hidden_tls_proto (name, ##attrs)
# define libutil_hidden_def(name) hidden_def (name)
# define libutil_hidden_weak(name) hidden_weak (name)
# define libutil_hidden_ver(local, name) hidden_ver (local, name)
# define libutil_hidden_data_def(name) hidden_data_def (name)
# define libutil_hidden_data_weak(name) hidden_data_weak (name)
# define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libutil_hidden_proto(name, attrs...)
# define libutil_hidden_tls_proto(name, attrs...)
# define libutil_hidden_def(name)
# define libutil_hidden_weak(name)
# define libutil_hidden_ver(local, name)
# define libutil_hidden_data_def(name)
# define libutil_hidden_data_weak(name)
# define libutil_hidden_data_ver(local, name)
#endif

/* Get some dirty hacks.  */
#include <symbol-hacks.h>

/* Move compatibility symbols out of the way by placing them all in a
   special section.  */
#ifndef __ASSEMBLER__
# define attribute_compat_text_section \
    __attribute__ ((section (".text.compat")))
# define attribute_compat_data_section \
    __attribute__ ((section (".data.compat")))
#else
# define compat_text_section .section ".text.compat", "ax";
# define compat_data_section .section ".data.compat", "aw";
#endif

/* Helper / base  macros for indirect function symbols.  */
#define __ifunc_resolver(type_name, name, expr, arg, init, classifier)	\
  classifier inhibit_stack_protector void *name##_ifunc (arg)					\
  {									\
    init ();								\
    __typeof (type_name) *res = expr;					\
    return res;								\
  }

#ifdef HAVE_GCC_IFUNC
# define __ifunc(type_name, name, expr, arg, init)			\
  extern __typeof (type_name) name __attribute__			\
			      ((ifunc (#name "_ifunc")));		\
  __ifunc_resolver (type_name, name, expr, arg, init, static)

# define __ifunc_hidden(type_name, name, expr, arg, init)	\
  __ifunc (type_name, name, expr, arg, init)
#else
/* Gcc does not support __attribute__ ((ifunc (...))).  Use the old behaviour
   as fallback.  But keep in mind that the debug information for the ifunc
   resolver functions is not correct.  It contains the ifunc'ed function as
   DW_AT_linkage_name.  E.g. lldb uses this field and an inferior function
   call of the ifunc'ed function will fail due to "no matching function for
   call to ..." because the ifunc'ed function and the resolver function have
   different signatures.  (Gcc support is disabled at least on a ppc64le
   Ubuntu 14.04 system.)  */

# define __ifunc(type_name, name, expr, arg, init)			\
  extern __typeof (type_name) name;					\
  void *name##_ifunc (arg) __asm__ (#name);				\
  __ifunc_resolver (type_name, name, expr, arg, init,)			\
 __asm__ (".type " #name ", %gnu_indirect_function");

# define __ifunc_hidden(type_name, name, expr, arg, init)		\
  extern __typeof (type_name) __libc_##name;				\
  __ifunc (type_name, __libc_##name, expr, arg, init)			\
  strong_alias (__libc_##name, name);
#endif /* !HAVE_GCC_IFUNC  */

/* The following macros are used for indirect function symbols in libc.so.
   First of all, you need to have the function prototyped somewhere,
   say in foo.h:

   int foo (int __bar);

   If you have an implementation for foo which e.g. uses a special hardware
   feature which isn't available on all machines where this libc.so will be
   used but decideable if available at runtime e.g. via hwcaps, you can provide
   two or multiple implementations of foo:

   int __foo_default (int __bar)
   {
     return __bar;
   }

   int __foo_special (int __bar)
   {
     return __bar;
   }

   If your function foo has no libc_hidden_proto (foo) defined for PLT
   bypassing, you can use:

   #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);

   libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);

   This will define a resolver function for foo which returns __foo_special or
   __foo_default depending on your specified expression.  Please note that you
   have to define a macro function INIT_ARCH before using libc_ifunc macro as
   it is called by the resolver function before evaluating the specified
   expression.  In this example it is used to prepare the hwcap variable.
   The resolver function is assigned to an ifunc'ed symbol foo.  Calls to foo
   from inside or outside of libc.so will be indirected by a PLT call.

   If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
   and calls to foo within libc.so should always go to one specific
   implementation of foo e.g. __foo_default then you have to add:

   __hidden_ver1 (__foo_default, __GI_foo, __foo_default);

   or a tweaked definition of libc_hidden_def macro after the __foo_default
   function definition.  Calls to foo within libc.so will always go directly to
   __foo_default.  Calls to foo from outside libc.so will be indirected by a
   PLT call to ifunc'ed symbol foo which you have to define in a separate
   compile unit:

   #define foo __redirect_foo
   #include <foo.h>
   #undef foo

   extern __typeof (__redirect_foo) __foo_default attribute_hidden;
   extern __typeof (__redirect_foo) __foo_special attribute_hidden;

   libc_ifunc_redirected (__redirect_foo, foo,
			  (hwcap & HWCAP_SPECIAL)
			  ? __foo_special
			  : __foo_default);

   This will define the ifunc'ed symbol foo like above.  The redirection of foo
   in header file is needed to omit an additional defintion of __GI_foo which
   would end in a linker error while linking libc.so.  You have to specify
   __redirect_foo as first parameter which is used within libc_ifunc_redirected
   macro in conjunction with typeof to define the ifunc'ed symbol foo.

   If your function foo has a libc_hidden_proto (foo) defined and calls to foo
   within or from outside libc.so should go via ifunc'ed symbol, then you have
   to use:

   libc_ifunc_hidden (foo, foo,
		      (hwcap & HWCAP_SPECIAL)
		      ? __foo_special
		      : __foo_default);
   libc_hidden_def (foo)

   The first parameter foo of libc_ifunc_hidden macro is used in the same way
   as for libc_ifunc_redirected macro.  */

#define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)

#define libc_ifunc_redirected(redirected_name, name, expr)	\
  __ifunc (redirected_name, name, expr, void, INIT_ARCH)

#define libc_ifunc_hidden(redirected_name, name, expr)			\
  __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)

/* The body of the function is supposed to use __get_cpu_features
   which will, if necessary, initialize the data first.  */
#define libm_ifunc_init()
#define libm_ifunc(name, expr)				\
  __ifunc (name, name, expr, void, libm_ifunc_init)

/* Add the compiler optimization to inhibit loop transformation to library
   calls.  This is used to avoid recursive calls in memset and memmove
   default implementations.  */
#ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
# define inhibit_loop_to_libcall \
    __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
#else
# define inhibit_loop_to_libcall
#endif

/* These macros facilitate sharing source files with gnulib.

   They are here instead of sys/cdefs.h because they should not be
   used in public header files.

   Their definitions should be kept consistent with the definitions in
   gnulib-common.m4, but it is not necessary to cater to old non-GCC
   compilers, since they will only be used while building glibc itself.
   (Note that _GNUC_PREREQ cannot be used in this file.)  */

/* Define as a marker that can be attached to declarations that might not
    be used.  This helps to reduce warnings, such as from
    GCC -Wunused-parameter.  */
#if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
# define _GL_UNUSED __attribute__ ((__unused__))
#else
# define _GL_UNUSED
#endif

/* gcc supports the "unused" attribute on possibly unused labels, and
   g++ has since version 4.5.  Note to support C++ as well as C,
   _GL_UNUSED_LABEL should be used with a trailing ;  */
#if !defined __cplusplus || __GNUC__ > 4 \
    || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
# define _GL_UNUSED_LABEL _GL_UNUSED
#else
# define _GL_UNUSED_LABEL
#endif

/* The __pure__ attribute was added in gcc 2.96.  */
#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
#else
# define _GL_ATTRIBUTE_PURE /* empty */
#endif

/* The __const__ attribute was added in gcc 2.95.  */
#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
# define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
#else
# define _GL_ATTRIBUTE_CONST /* empty */
#endif

#endif /* libc-symbols.h */