1/* Support macros for making weak and strong aliases for symbols,
2 and for using symbol sets and linker warnings with GNU ld.
3 Copyright (C) 1995-2017 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
19
20#ifndef _LIBC_SYMBOLS_H
21#define _LIBC_SYMBOLS_H 1
22
23/* This file is included implicitly in the compilation of every source file,
24 using -include. It includes config.h. */
25
26/* Enable declarations of GNU extensions, since we are compiling them. */
27#define _GNU_SOURCE 1
28
29#ifdef MODULE_NAME
30
31/* Use `#if IS_IN (module)` to detect what component is being compiled. */
32#define PASTE_NAME1(a,b) a##b
33#define PASTE_NAME(a,b) PASTE_NAME1 (a,b)
34#define IN_MODULE PASTE_NAME (MODULE_, MODULE_NAME)
35#define IS_IN(lib) (IN_MODULE == MODULE_##lib)
36
37/* True if the current module is a versioned library. Versioned
38 library names culled from shlib-versions files are assigned a
39 MODULE_* value greater than MODULE_LIBS_BEGIN. */
40#define IS_IN_LIB (IN_MODULE > MODULE_LIBS_BEGIN)
41
42/* The testsuite, and some other ancillary code, should be compiled against
43 as close an approximation to the installed headers as possible.
44 Defining this symbol disables most internal-use-only declarations
45 provided by this header, and all those provided by other internal
46 wrapper headers. */
47#if IS_IN (testsuite) || defined IS_IN_build || defined __cplusplus
48# define _ISOMAC 1
49#endif
50
51#else
52/* The generation process for a few files created very early in the
53 build (notably libc-modules.h itself) involves preprocessing this
54 header without defining MODULE_NAME. Under these conditions,
55 internal declarations (especially from config.h) must be visible,
56 but IS_IN should always evaluate as false. */
57# define IS_IN(lib) 0
58# define IS_IN_LIB 0
59# define IN_MODULE (-1)
60#endif
61
62#ifndef _ISOMAC
63
64/* This is defined for the compilation of all C library code. features.h
65 tests this to avoid inclusion of stubs.h while compiling the library,
66 before stubs.h has been generated. Some library code that is shared
67 with other packages also tests this symbol to see if it is being
68 compiled as part of the C library. We must define this before including
69 config.h, because it makes some definitions conditional on whether libc
70 itself is being compiled, or just some generator program. */
71#define _LIBC 1
72
73/* Some files must be compiled with optimization on. */
74#if !defined __ASSEMBLER__ && !defined __OPTIMIZE__
75# error "glibc cannot be compiled without optimization"
76#endif
77
78/* -ffast-math cannot be applied to the C library, as it alters the ABI.
79 Some test components that use -ffast-math are currently not part of
80 IS_IN (testsuite) for technical reasons, so we have a secondary override. */
81#if defined __FAST_MATH__ && !defined TEST_FAST_MATH
82# error "glibc must not be compiled with -ffast-math"
83#endif
84
85#include <config.h>
86
87/* Define this for the benefit of portable GNU code that wants to check it.
88 Code that checks with #if will not #include <config.h> again, since we've
89 already done it (and this file is implicitly included in every compile,
90 via -include). Code that checks with #ifdef will #include <config.h>,
91 but that file should always be idempotent (i.e., it's just #define/#undef
92 and nothing else anywhere should be changing the macro state it touches),
93 so it's harmless. */
94#define HAVE_CONFIG_H 0
95
96/* Define these macros for the benefit of portable GNU code that wants to check
97 them. Of course, STDC_HEADERS is never false when building libc! */
98#define STDC_HEADERS 1
99#define HAVE_MBSTATE_T 1
100#define HAVE_MBSRTOWCS 1
101#define HAVE_LIBINTL_H 1
102#define HAVE_WCTYPE_H 1
103#define HAVE_ISWCTYPE 1
104#define ENABLE_NLS 1
105
106/* The symbols in all the user (non-_) macros are C symbols. */
107
108#ifndef __SYMBOL_PREFIX
109# define __SYMBOL_PREFIX
110#endif
111
112#ifndef C_SYMBOL_NAME
113# define C_SYMBOL_NAME(name) name
114#endif
115
116#ifndef ASM_LINE_SEP
117# define ASM_LINE_SEP ;
118#endif
119
120#ifndef __ASSEMBLER__
121/* GCC understands weak symbols and aliases; use its interface where
122 possible, instead of embedded assembly language. */
123
124/* Define ALIASNAME as a strong alias for NAME. */
125# define strong_alias(name, aliasname) _strong_alias(name, aliasname)
126# define _strong_alias(name, aliasname) \
127 extern __typeof (name) aliasname __attribute__ ((alias (#name)));
128
129/* This comes between the return type and function name in
130 a function definition to make that definition weak. */
131# define weak_function __attribute__ ((weak))
132# define weak_const_function __attribute__ ((weak, __const__))
133
134/* Define ALIASNAME as a weak alias for NAME.
135 If weak aliases are not available, this defines a strong alias. */
136# define weak_alias(name, aliasname) _weak_alias (name, aliasname)
137# define _weak_alias(name, aliasname) \
138 extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
139
140/* Same as WEAK_ALIAS, but mark symbol as hidden. */
141# define weak_hidden_alias(name, aliasname) \
142 _weak_hidden_alias (name, aliasname)
143# define _weak_hidden_alias(name, aliasname) \
144 extern __typeof (name) aliasname \
145 __attribute__ ((weak, alias (#name), __visibility__ ("hidden")));
146
147/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */
148# define weak_extern(symbol) _weak_extern (weak symbol)
149# define _weak_extern(expr) _Pragma (#expr)
150
151/* In shared builds, the expression call_function_static_weak
152 (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
153 identifier) unconditionally, with the (potentially empty) argument
154 list ARGUMENTS. In static builds, if FUNCTION-SYMBOL has a
155 definition, the function is invoked as before; if FUNCTION-SYMBOL
156 is NULL, no call is performed. */
157# ifdef SHARED
158# define call_function_static_weak(func, ...) func (__VA_ARGS__)
159# else /* !SHARED */
160# define call_function_static_weak(func, ...) \
161 ({ \
162 extern __typeof__ (func) func weak_function; \
163 (func != NULL ? func (__VA_ARGS__) : (void)0); \
164 })
165# endif
166
167#else /* __ASSEMBLER__ */
168
169# ifdef HAVE_ASM_SET_DIRECTIVE
170# define strong_alias(original, alias) \
171 .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
172 .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
173# define strong_data_alias(original, alias) strong_alias(original, alias)
174# else
175# define strong_alias(original, alias) \
176 .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
177 C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
178# define strong_data_alias(original, alias) strong_alias(original, alias)
179# endif
180
181# define weak_alias(original, alias) \
182 .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP \
183 C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
184
185# define weak_extern(symbol) \
186 .weak C_SYMBOL_NAME (symbol)
187
188#endif /* __ASSEMBLER__ */
189
190/* On some platforms we can make internal function calls (i.e., calls of
191 functions not exported) a bit faster by using a different calling
192 convention. */
193#ifndef internal_function
194# define internal_function /* empty */
195#endif
196
197/* Determine the return address. */
198#define RETURN_ADDRESS(nr) \
199 __builtin_extract_return_addr (__builtin_return_address (nr))
200
201/* When a reference to SYMBOL is encountered, the linker will emit a
202 warning message MSG. */
203/* We want the .gnu.warning.SYMBOL section to be unallocated. */
204#define __make_section_unallocated(section_string) \
205 asm (".section " section_string "\n\t.previous");
206
207/* Tacking on "\n\t#" to the section name makes gcc put it's bogus
208 section attributes on what looks like a comment to the assembler. */
209#ifdef HAVE_SECTION_QUOTES
210# define __sec_comment "\"\n\t#\""
211#else
212# define __sec_comment "\n\t#"
213#endif
214#define link_warning(symbol, msg) \
215 __make_section_unallocated (".gnu.warning." #symbol) \
216 static const char __evoke_link_warning_##symbol[] \
217 __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
218 = msg;
219#define libc_freeres_ptr(decl) \
220 __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
221 decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
222#define __libc_freeres_fn_section \
223 __attribute__ ((section ("__libc_freeres_fn")))
224
225#define libc_freeres_fn(name) \
226 static void name (void) __attribute_used__ __libc_freeres_fn_section; \
227 text_set_element (__libc_subfreeres, name); \
228 static void name (void)
229
230/* A canned warning for sysdeps/stub functions. */
231#define stub_warning(name) \
232 __make_section_unallocated (".gnu.glibc-stub." #name) \
233 link_warning (name, #name " is not implemented and will always fail")
234
235/* Warning for linking functions calling dlopen into static binaries. */
236#ifdef SHARED
237#define static_link_warning(name)
238#else
239#define static_link_warning(name) static_link_warning1(name)
240#define static_link_warning1(name) \
241 link_warning(name, "Using '" #name "' in statically linked applications \
242requires at runtime the shared libraries from the glibc version used \
243for linking")
244#endif
245
246/* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
247 alias to ORIGINAL, when the assembler supports such declarations
248 (such as in ELF).
249 This is only necessary when defining something in assembly, or playing
250 funny alias games where the size should be other than what the compiler
251 thinks it is. */
252#define declare_symbol_alias(symbol, original, type, size) \
253 declare_symbol_alias_1 (symbol, original, type, size)
254#ifdef __ASSEMBLER__
255# define declare_symbol_alias_1(symbol, original, type, size) \
256 strong_alias (original, symbol); \
257 .type C_SYMBOL_NAME (symbol), %##type; \
258 .size C_SYMBOL_NAME (symbol), size
259#else /* Not __ASSEMBLER__. */
260# define declare_symbol_alias_1(symbol, original, type, size) \
261 asm (".globl " __SYMBOL_PREFIX #symbol \
262 "\n\t" declare_symbol_alias_1_alias (symbol, original) \
263 "\n\t.type " __SYMBOL_PREFIX #symbol ", " \
264 "%" #type \
265 "\n\t.size " __SYMBOL_PREFIX #symbol ", " #size);
266# ifdef HAVE_ASM_SET_DIRECTIVE
267# define declare_symbol_alias_1_alias(symbol, original) \
268 ".set " __SYMBOL_PREFIX #symbol ", " __SYMBOL_PREFIX #original
269# else
270# define declare_symbol_alias_1_alias(symbol, original) \
271 __SYMBOL_PREFIX #symbol " = " __SYMBOL_PREFIX #original
272# endif /* HAVE_ASM_SET_DIRECTIVE */
273#endif /* __ASSEMBLER__ */
274
275
276/*
277
278*/
279
280/* Symbol set support macros. */
281
282/* Make SYMBOL, which is in the text segment, an element of SET. */
283#define text_set_element(set, symbol) _elf_set_element(set, symbol)
284/* Make SYMBOL, which is in the data segment, an element of SET. */
285#define data_set_element(set, symbol) _elf_set_element(set, symbol)
286/* Make SYMBOL, which is in the bss segment, an element of SET. */
287#define bss_set_element(set, symbol) _elf_set_element(set, symbol)
288
289/* These are all done the same way in ELF.
290 There is a new section created for each set. */
291#ifdef SHARED
292/* When building a shared library, make the set section writable,
293 because it will need to be relocated at run time anyway. */
294# define _elf_set_element(set, symbol) \
295 static const void *__elf_set_##set##_element_##symbol##__ \
296 __attribute__ ((used, section (#set))) = &(symbol)
297#else
298# define _elf_set_element(set, symbol) \
299 static const void *const __elf_set_##set##_element_##symbol##__ \
300 __attribute__ ((used, section (#set))) = &(symbol)
301#endif
302
303/* Define SET as a symbol set. This may be required (it is in a.out) to
304 be able to use the set's contents. */
305#define symbol_set_define(set) symbol_set_declare(set)
306
307/* Declare SET for use in this module, if defined in another module.
308 In a shared library, this is always local to that shared object.
309 For static linking, the set might be wholly absent and so we use
310 weak references. */
311#define symbol_set_declare(set) \
312 extern char const __start_##set[] __symbol_set_attribute; \
313 extern char const __stop_##set[] __symbol_set_attribute;
314#ifdef SHARED
315# define __symbol_set_attribute attribute_hidden
316#else
317# define __symbol_set_attribute __attribute__ ((weak))
318#endif
319
320/* Return a pointer (void *const *) to the first element of SET. */
321#define symbol_set_first_element(set) ((void *const *) (&__start_##set))
322
323/* Return true iff PTR (a void *const *) has been incremented
324 past the last element in SET. */
325#define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
326
327/* Use symbol_version_reference to specify the version a symbol
328 reference should link to. Use symbol_version or
329 default_symbol_version for the definition of a versioned symbol.
330 The difference is that the latter is a no-op in non-shared
331 builds. */
332#ifdef __ASSEMBLER__
333# define symbol_version_reference(real, name, version) \
334 .symver real, name##@##version
335#else /* !__ASSEMBLER__ */
336# define symbol_version_reference(real, name, version) \
337 __asm__ (".symver " #real "," #name "@" #version)
338#endif
339
340#ifdef SHARED
341# define symbol_version(real, name, version) \
342 symbol_version_reference(real, name, version)
343# define default_symbol_version(real, name, version) \
344 _default_symbol_version(real, name, version)
345# ifdef __ASSEMBLER__
346# define _default_symbol_version(real, name, version) \
347 .symver real, name##@##@##version
348# else
349# define _default_symbol_version(real, name, version) \
350 __asm__ (".symver " #real "," #name "@@" #version)
351# endif
352#else
353# define symbol_version(real, name, version)
354# define default_symbol_version(real, name, version) \
355 strong_alias(real, name)
356#endif
357
358#if defined SHARED || defined LIBC_NONSHARED
359# define attribute_hidden __attribute__ ((visibility ("hidden")))
360#else
361# define attribute_hidden
362#endif
363
364#define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
365
366#define attribute_relro __attribute__ ((section (".data.rel.ro")))
367
368
369/* Used to disable stack protection in sensitive places, like ifunc
370 resolvers and early static TLS init. */
371#ifdef HAVE_CC_NO_STACK_PROTECTOR
372# define inhibit_stack_protector \
373 __attribute__ ((__optimize__ ("-fno-stack-protector")))
374#else
375# define inhibit_stack_protector
376#endif
377
378/* The following macros are used for PLT bypassing within libc.so
379 (and if needed other libraries similarly).
380 First of all, you need to have the function prototyped somewhere,
381 say in foo/foo.h:
382
383 int foo (int __bar);
384
385 If calls to foo within libc.so should always go to foo defined in libc.so,
386 then in include/foo.h you add:
387
388 libc_hidden_proto (foo)
389
390 line and after the foo function definition:
391
392 int foo (int __bar)
393 {
394 return __bar;
395 }
396 libc_hidden_def (foo)
397
398 or
399
400 int foo (int __bar)
401 {
402 return __bar;
403 }
404 libc_hidden_weak (foo)
405
406 Similarly for global data. If references to foo within libc.so should
407 always go to foo defined in libc.so, then in include/foo.h you add:
408
409 libc_hidden_proto (foo)
410
411 line and after foo's definition:
412
413 int foo = INITIAL_FOO_VALUE;
414 libc_hidden_data_def (foo)
415
416 or
417
418 int foo = INITIAL_FOO_VALUE;
419 libc_hidden_data_weak (foo)
420
421 If foo is normally just an alias (strong or weak) to some other function,
422 you should use the normal strong_alias first, then add libc_hidden_def
423 or libc_hidden_weak:
424
425 int baz (int __bar)
426 {
427 return __bar;
428 }
429 strong_alias (baz, foo)
430 libc_hidden_weak (foo)
431
432 If the function should be internal to multiple objects, say ld.so and
433 libc.so, the best way is to use:
434
435 #if IS_IN (libc) || IS_IN (rtld)
436 hidden_proto (foo)
437 #endif
438
439 in include/foo.h and the normal macros at all function definitions
440 depending on what DSO they belong to.
441
442 If versioned_symbol macro is used to define foo,
443 libc_hidden_ver macro should be used, as in:
444
445 int __real_foo (int __bar)
446 {
447 return __bar;
448 }
449 versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
450 libc_hidden_ver (__real_foo, foo) */
451
452#if defined SHARED && !defined NO_HIDDEN
453# ifndef __ASSEMBLER__
454# define __hidden_proto_hiddenattr(attrs...) \
455 __attribute__ ((visibility ("hidden"), ##attrs))
456# define hidden_proto(name, attrs...) \
457 __hidden_proto (name, , __GI_##name, ##attrs)
458# define hidden_tls_proto(name, attrs...) \
459 __hidden_proto (name, __thread, __GI_##name, ##attrs)
460# define __hidden_proto(name, thread, internal, attrs...) \
461 extern thread __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
462 __hidden_proto_hiddenattr (attrs);
463# define __hidden_asmname(name) \
464 __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
465# define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
466# define __hidden_asmname2(prefix, name) #prefix name
467# define __hidden_ver1(local, internal, name) \
468 extern __typeof (name) __EI_##name __asm__(__hidden_asmname (#internal)); \
469 extern __typeof (name) __EI_##name \
470 __attribute__((alias (__hidden_asmname (#local))))
471# define hidden_ver(local, name) __hidden_ver1(local, __GI_##name, name);
472# define hidden_data_ver(local, name) hidden_ver(local, name)
473# define hidden_def(name) __hidden_ver1(__GI_##name, name, name);
474# define hidden_data_def(name) hidden_def(name)
475# define hidden_weak(name) \
476 __hidden_ver1(__GI_##name, name, name) __attribute__((weak));
477# define hidden_data_weak(name) hidden_weak(name)
478# define hidden_nolink(name, lib, version) \
479 __hidden_nolink1 (__GI_##name, __EI_##name, name, VERSION_##lib##_##version)
480# define __hidden_nolink1(local, internal, name, version) \
481 __hidden_nolink2 (local, internal, name, version)
482# define __hidden_nolink2(local, internal, name, version) \
483 extern __typeof (name) internal __attribute__ ((alias (#local))); \
484 __hidden_nolink3 (local, internal, #name "@" #version)
485# define __hidden_nolink3(local, internal, vername) \
486 __asm__ (".symver " #internal ", " vername);
487# else
488/* For assembly, we need to do the opposite of what we do in C:
489 in assembly gcc __REDIRECT stuff is not in place, so functions
490 are defined by its normal name and we need to create the
491 __GI_* alias to it, in C __REDIRECT causes the function definition
492 to use __GI_* name and we need to add alias to the real name.
493 There is no reason to use hidden_weak over hidden_def in assembly,
494 but we provide it for consistency with the C usage.
495 hidden_proto doesn't make sense for assembly but the equivalent
496 is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET. */
497# define hidden_def(name) strong_alias (name, __GI_##name)
498# define hidden_weak(name) hidden_def (name)
499# define hidden_ver(local, name) strong_alias (local, __GI_##name)
500# define hidden_data_def(name) strong_data_alias (name, __GI_##name)
501# define hidden_data_weak(name) hidden_data_def (name)
502# define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
503# define HIDDEN_JUMPTARGET(name) __GI_##name
504# endif
505#else
506# ifndef __ASSEMBLER__
507# define hidden_proto(name, attrs...)
508# define hidden_tls_proto(name, attrs...)
509# else
510# define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
511# endif /* Not __ASSEMBLER__ */
512# define hidden_weak(name)
513# define hidden_def(name)
514# define hidden_ver(local, name)
515# define hidden_data_weak(name)
516# define hidden_data_def(name)
517# define hidden_data_ver(local, name)
518# define hidden_nolink(name, lib, version)
519#endif
520
521#if IS_IN (libc)
522# define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
523# define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
524# define libc_hidden_def(name) hidden_def (name)
525# define libc_hidden_weak(name) hidden_weak (name)
526# ifdef LINK_OBSOLETE_RPC
527 /* libc_hidden_nolink_sunrpc should only get used in sunrpc code. */
528# define libc_hidden_nolink_sunrpc(name, version) hidden_def (name)
529# else
530# define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
531# endif
532# define libc_hidden_ver(local, name) hidden_ver (local, name)
533# define libc_hidden_data_def(name) hidden_data_def (name)
534# define libc_hidden_data_weak(name) hidden_data_weak (name)
535# define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
536#else
537# define libc_hidden_proto(name, attrs...)
538# define libc_hidden_tls_proto(name, attrs...)
539# define libc_hidden_def(name)
540# define libc_hidden_weak(name)
541# define libc_hidden_ver(local, name)
542# define libc_hidden_data_def(name)
543# define libc_hidden_data_weak(name)
544# define libc_hidden_data_ver(local, name)
545#endif
546
547#if IS_IN (rtld)
548# define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
549# define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
550# define rtld_hidden_def(name) hidden_def (name)
551# define rtld_hidden_weak(name) hidden_weak (name)
552# define rtld_hidden_ver(local, name) hidden_ver (local, name)
553# define rtld_hidden_data_def(name) hidden_data_def (name)
554# define rtld_hidden_data_weak(name) hidden_data_weak (name)
555# define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
556#else
557# define rtld_hidden_proto(name, attrs...)
558# define rtld_hidden_tls_proto(name, attrs...)
559# define rtld_hidden_def(name)
560# define rtld_hidden_weak(name)
561# define rtld_hidden_ver(local, name)
562# define rtld_hidden_data_def(name)
563# define rtld_hidden_data_weak(name)
564# define rtld_hidden_data_ver(local, name)
565#endif
566
567#if IS_IN (libm)
568# define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
569# define libm_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
570# define libm_hidden_def(name) hidden_def (name)
571# define libm_hidden_weak(name) hidden_weak (name)
572# define libm_hidden_ver(local, name) hidden_ver (local, name)
573# define libm_hidden_data_def(name) hidden_data_def (name)
574# define libm_hidden_data_weak(name) hidden_data_weak (name)
575# define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
576#else
577# define libm_hidden_proto(name, attrs...)
578# define libm_hidden_tls_proto(name, attrs...)
579# define libm_hidden_def(name)
580# define libm_hidden_weak(name)
581# define libm_hidden_ver(local, name)
582# define libm_hidden_data_def(name)
583# define libm_hidden_data_weak(name)
584# define libm_hidden_data_ver(local, name)
585#endif
586
587#if IS_IN (libmvec)
588# define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
589# define libmvec_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
590# define libmvec_hidden_def(name) hidden_def (name)
591# define libmvec_hidden_weak(name) hidden_weak (name)
592# define libmvec_hidden_ver(local, name) hidden_ver (local, name)
593# define libmvec_hidden_data_def(name) hidden_data_def (name)
594# define libmvec_hidden_data_weak(name) hidden_data_weak (name)
595# define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
596#else
597# define libmvec_hidden_proto(name, attrs...)
598# define libmvec_hidden_tls_proto(name, attrs...)
599# define libmvec_hidden_def(name)
600# define libmvec_hidden_weak(name)
601# define libmvec_hidden_ver(local, name)
602# define libmvec_hidden_data_def(name)
603# define libmvec_hidden_data_weak(name)
604# define libmvec_hidden_data_ver(local, name)
605#endif
606
607#if IS_IN (libresolv)
608# define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
609# define libresolv_hidden_tls_proto(name, attrs...) \
610 hidden_tls_proto (name, ##attrs)
611# define libresolv_hidden_def(name) hidden_def (name)
612# define libresolv_hidden_weak(name) hidden_weak (name)
613# define libresolv_hidden_ver(local, name) hidden_ver (local, name)
614# define libresolv_hidden_data_def(name) hidden_data_def (name)
615# define libresolv_hidden_data_weak(name) hidden_data_weak (name)
616# define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
617#else
618# define libresolv_hidden_proto(name, attrs...)
619# define libresolv_hidden_tls_proto(name, attrs...)
620# define libresolv_hidden_def(name)
621# define libresolv_hidden_weak(name)
622# define libresolv_hidden_ver(local, name)
623# define libresolv_hidden_data_def(name)
624# define libresolv_hidden_data_weak(name)
625# define libresolv_hidden_data_ver(local, name)
626#endif
627
628#if IS_IN (librt)
629# define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
630# define librt_hidden_tls_proto(name, attrs...) \
631 hidden_tls_proto (name, ##attrs)
632# define librt_hidden_def(name) hidden_def (name)
633# define librt_hidden_weak(name) hidden_weak (name)
634# define librt_hidden_ver(local, name) hidden_ver (local, name)
635# define librt_hidden_data_def(name) hidden_data_def (name)
636# define librt_hidden_data_weak(name) hidden_data_weak (name)
637# define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
638#else
639# define librt_hidden_proto(name, attrs...)
640# define librt_hidden_tls_proto(name, attrs...)
641# define librt_hidden_def(name)
642# define librt_hidden_weak(name)
643# define librt_hidden_ver(local, name)
644# define librt_hidden_data_def(name)
645# define librt_hidden_data_weak(name)
646# define librt_hidden_data_ver(local, name)
647#endif
648
649#if IS_IN (libdl)
650# define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
651# define libdl_hidden_tls_proto(name, attrs...) \
652 hidden_tls_proto (name, ##attrs)
653# define libdl_hidden_def(name) hidden_def (name)
654# define libdl_hidden_weak(name) hidden_weak (name)
655# define libdl_hidden_ver(local, name) hidden_ver (local, name)
656# define libdl_hidden_data_def(name) hidden_data_def (name)
657# define libdl_hidden_data_weak(name) hidden_data_weak (name)
658# define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
659#else
660# define libdl_hidden_proto(name, attrs...)
661# define libdl_hidden_tls_proto(name, attrs...)
662# define libdl_hidden_def(name)
663# define libdl_hidden_weak(name)
664# define libdl_hidden_ver(local, name)
665# define libdl_hidden_data_def(name)
666# define libdl_hidden_data_weak(name)
667# define libdl_hidden_data_ver(local, name)
668#endif
669
670#if IS_IN (libnss_files)
671# define libnss_files_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
672# define libnss_files_hidden_tls_proto(name, attrs...) \
673 hidden_tls_proto (name, ##attrs)
674# define libnss_files_hidden_def(name) hidden_def (name)
675# define libnss_files_hidden_weak(name) hidden_weak (name)
676# define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
677# define libnss_files_hidden_data_def(name) hidden_data_def (name)
678# define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
679# define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
680#else
681# define libnss_files_hidden_proto(name, attrs...)
682# define libnss_files_hidden_tls_proto(name, attrs...)
683# define libnss_files_hidden_def(name)
684# define libnss_files_hidden_weak(name)
685# define libnss_files_hidden_ver(local, name)
686# define libnss_files_hidden_data_def(name)
687# define libnss_files_hidden_data_weak(name)
688# define libnss_files_hidden_data_ver(local, name)
689#endif
690
691#if IS_IN (libnsl)
692# define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
693# define libnsl_hidden_tls_proto(name, attrs...) \
694 hidden_tls_proto (name, ##attrs)
695# ifdef LINK_OBSOLETE_NSL
696 /* libnsl_hidden_nolink should only get used in libnsl code. */
697# define libnsl_hidden_nolink_def(name, version) libnsl_hidden_def (name)
698# else
699# define libnsl_hidden_nolink_def(name, version) hidden_nolink (name, libnsl, version)
700# endif
701# define libnsl_hidden_def(name) hidden_def (name)
702# define libnsl_hidden_weak(name) hidden_weak (name)
703# define libnsl_hidden_ver(local, name) hidden_ver (local, name)
704# define libnsl_hidden_data_def(name) hidden_data_def (name)
705# define libnsl_hidden_data_weak(name) hidden_data_weak (name)
706# define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
707#else
708# define libnsl_hidden_proto(name, attrs...)
709# define libnsl_hidden_tls_proto(name, attrs...)
710# define libnsl_hidden_def(name)
711# define libnsl_hidden_weak(name)
712# define libnsl_hidden_ver(local, name)
713# define libnsl_hidden_data_def(name)
714# define libnsl_hidden_data_weak(name)
715# define libnsl_hidden_data_ver(local, name)
716#endif
717
718#if IS_IN (libnss_nisplus)
719# define libnss_nisplus_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
720# define libnss_nisplus_hidden_tls_proto(name, attrs...) \
721 hidden_tls_proto (name, ##attrs)
722# define libnss_nisplus_hidden_def(name) hidden_def (name)
723# define libnss_nisplus_hidden_weak(name) hidden_weak (name)
724# define libnss_nisplus_hidden_ver(local, name) hidden_ver (local, name)
725# define libnss_nisplus_hidden_data_def(name) hidden_data_def (name)
726# define libnss_nisplus_hidden_data_weak(name) hidden_data_weak (name)
727# define libnss_nisplus_hidden_data_ver(local, name) hidden_data_ver (local, name)
728#else
729# define libnss_nisplus_hidden_proto(name, attrs...)
730# define libnss_nisplus_hidden_tls_proto(name, attrs...)
731# define libnss_nisplus_hidden_def(name)
732# define libnss_nisplus_hidden_weak(name)
733# define libnss_nisplus_hidden_ver(local, name)
734# define libnss_nisplus_hidden_data_def(name)
735# define libnss_nisplus_hidden_data_weak(name)
736# define libnss_nisplus_hidden_data_ver(local, name)
737#endif
738
739#define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
740#define libc_hidden_builtin_def(name) libc_hidden_def (name)
741#define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
742#define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
743#ifdef __ASSEMBLER__
744# define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
745#endif
746
747#if IS_IN (libutil)
748# define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
749# define libutil_hidden_tls_proto(name, attrs...) \
750 hidden_tls_proto (name, ##attrs)
751# define libutil_hidden_def(name) hidden_def (name)
752# define libutil_hidden_weak(name) hidden_weak (name)
753# define libutil_hidden_ver(local, name) hidden_ver (local, name)
754# define libutil_hidden_data_def(name) hidden_data_def (name)
755# define libutil_hidden_data_weak(name) hidden_data_weak (name)
756# define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
757#else
758# define libutil_hidden_proto(name, attrs...)
759# define libutil_hidden_tls_proto(name, attrs...)
760# define libutil_hidden_def(name)
761# define libutil_hidden_weak(name)
762# define libutil_hidden_ver(local, name)
763# define libutil_hidden_data_def(name)
764# define libutil_hidden_data_weak(name)
765# define libutil_hidden_data_ver(local, name)
766#endif
767
768/* Get some dirty hacks. */
769#include <symbol-hacks.h>
770
771/* Move compatibility symbols out of the way by placing them all in a
772 special section. */
773#ifndef __ASSEMBLER__
774# define attribute_compat_text_section \
775 __attribute__ ((section (".text.compat")))
776# define attribute_compat_data_section \
777 __attribute__ ((section (".data.compat")))
778#else
779# define compat_text_section .section ".text.compat", "ax";
780# define compat_data_section .section ".data.compat", "aw";
781#endif
782
783/* Helper / base macros for indirect function symbols. */
784#define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \
785 classifier inhibit_stack_protector void *name##_ifunc (arg) \
786 { \
787 init (); \
788 __typeof (type_name) *res = expr; \
789 return res; \
790 }
791
792#ifdef HAVE_GCC_IFUNC
793# define __ifunc(type_name, name, expr, arg, init) \
794 extern __typeof (type_name) name __attribute__ \
795 ((ifunc (#name "_ifunc"))); \
796 __ifunc_resolver (type_name, name, expr, arg, init, static)
797
798# define __ifunc_hidden(type_name, name, expr, arg, init) \
799 __ifunc (type_name, name, expr, arg, init)
800#else
801/* Gcc does not support __attribute__ ((ifunc (...))). Use the old behaviour
802 as fallback. But keep in mind that the debug information for the ifunc
803 resolver functions is not correct. It contains the ifunc'ed function as
804 DW_AT_linkage_name. E.g. lldb uses this field and an inferior function
805 call of the ifunc'ed function will fail due to "no matching function for
806 call to ..." because the ifunc'ed function and the resolver function have
807 different signatures. (Gcc support is disabled at least on a ppc64le
808 Ubuntu 14.04 system.) */
809
810# define __ifunc(type_name, name, expr, arg, init) \
811 extern __typeof (type_name) name; \
812 void *name##_ifunc (arg) __asm__ (#name); \
813 __ifunc_resolver (type_name, name, expr, arg, init,) \
814 __asm__ (".type " #name ", %gnu_indirect_function");
815
816# define __ifunc_hidden(type_name, name, expr, arg, init) \
817 extern __typeof (type_name) __libc_##name; \
818 __ifunc (type_name, __libc_##name, expr, arg, init) \
819 strong_alias (__libc_##name, name);
820#endif /* !HAVE_GCC_IFUNC */
821
822/* The following macros are used for indirect function symbols in libc.so.
823 First of all, you need to have the function prototyped somewhere,
824 say in foo.h:
825
826 int foo (int __bar);
827
828 If you have an implementation for foo which e.g. uses a special hardware
829 feature which isn't available on all machines where this libc.so will be
830 used but decideable if available at runtime e.g. via hwcaps, you can provide
831 two or multiple implementations of foo:
832
833 int __foo_default (int __bar)
834 {
835 return __bar;
836 }
837
838 int __foo_special (int __bar)
839 {
840 return __bar;
841 }
842
843 If your function foo has no libc_hidden_proto (foo) defined for PLT
844 bypassing, you can use:
845
846 #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
847
848 libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
849
850 This will define a resolver function for foo which returns __foo_special or
851 __foo_default depending on your specified expression. Please note that you
852 have to define a macro function INIT_ARCH before using libc_ifunc macro as
853 it is called by the resolver function before evaluating the specified
854 expression. In this example it is used to prepare the hwcap variable.
855 The resolver function is assigned to an ifunc'ed symbol foo. Calls to foo
856 from inside or outside of libc.so will be indirected by a PLT call.
857
858 If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
859 and calls to foo within libc.so should always go to one specific
860 implementation of foo e.g. __foo_default then you have to add:
861
862 __hidden_ver1 (__foo_default, __GI_foo, __foo_default);
863
864 or a tweaked definition of libc_hidden_def macro after the __foo_default
865 function definition. Calls to foo within libc.so will always go directly to
866 __foo_default. Calls to foo from outside libc.so will be indirected by a
867 PLT call to ifunc'ed symbol foo which you have to define in a separate
868 compile unit:
869
870 #define foo __redirect_foo
871 #include <foo.h>
872 #undef foo
873
874 extern __typeof (__redirect_foo) __foo_default attribute_hidden;
875 extern __typeof (__redirect_foo) __foo_special attribute_hidden;
876
877 libc_ifunc_redirected (__redirect_foo, foo,
878 (hwcap & HWCAP_SPECIAL)
879 ? __foo_special
880 : __foo_default);
881
882 This will define the ifunc'ed symbol foo like above. The redirection of foo
883 in header file is needed to omit an additional defintion of __GI_foo which
884 would end in a linker error while linking libc.so. You have to specify
885 __redirect_foo as first parameter which is used within libc_ifunc_redirected
886 macro in conjunction with typeof to define the ifunc'ed symbol foo.
887
888 If your function foo has a libc_hidden_proto (foo) defined and calls to foo
889 within or from outside libc.so should go via ifunc'ed symbol, then you have
890 to use:
891
892 libc_ifunc_hidden (foo, foo,
893 (hwcap & HWCAP_SPECIAL)
894 ? __foo_special
895 : __foo_default);
896 libc_hidden_def (foo)
897
898 The first parameter foo of libc_ifunc_hidden macro is used in the same way
899 as for libc_ifunc_redirected macro. */
900
901#define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
902
903#define libc_ifunc_redirected(redirected_name, name, expr) \
904 __ifunc (redirected_name, name, expr, void, INIT_ARCH)
905
906#define libc_ifunc_hidden(redirected_name, name, expr) \
907 __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
908
909/* The body of the function is supposed to use __get_cpu_features
910 which will, if necessary, initialize the data first. */
911#define libm_ifunc_init()
912#define libm_ifunc(name, expr) \
913 __ifunc (name, name, expr, void, libm_ifunc_init)
914
915/* Add the compiler optimization to inhibit loop transformation to library
916 calls. This is used to avoid recursive calls in memset and memmove
917 default implementations. */
918#ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
919# define inhibit_loop_to_libcall \
920 __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
921#else
922# define inhibit_loop_to_libcall
923#endif
924
925/* These macros facilitate sharing source files with gnulib.
926
927 They are here instead of sys/cdefs.h because they should not be
928 used in public header files.
929
930 Their definitions should be kept consistent with the definitions in
931 gnulib-common.m4, but it is not necessary to cater to old non-GCC
932 compilers, since they will only be used while building glibc itself.
933 (Note that _GNUC_PREREQ cannot be used in this file.) */
934
935/* Define as a marker that can be attached to declarations that might not
936 be used. This helps to reduce warnings, such as from
937 GCC -Wunused-parameter. */
938#if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
939# define _GL_UNUSED __attribute__ ((__unused__))
940#else
941# define _GL_UNUSED
942#endif
943
944/* gcc supports the "unused" attribute on possibly unused labels, and
945 g++ has since version 4.5. Note to support C++ as well as C,
946 _GL_UNUSED_LABEL should be used with a trailing ; */
947#if !defined __cplusplus || __GNUC__ > 4 \
948 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
949# define _GL_UNUSED_LABEL _GL_UNUSED
950#else
951# define _GL_UNUSED_LABEL
952#endif
953
954/* The __pure__ attribute was added in gcc 2.96. */
955#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
956# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
957#else
958# define _GL_ATTRIBUTE_PURE /* empty */
959#endif
960
961/* The __const__ attribute was added in gcc 2.95. */
962#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
963# define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
964#else
965# define _GL_ATTRIBUTE_CONST /* empty */
966#endif
967
968#endif /* !_ISOMAC */
969#endif /* libc-symbols.h */
970