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.
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.
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.
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/>. */
20 #ifndef _LIBC_SYMBOLS_H
21 #define _LIBC_SYMBOLS_H 1
23 /* This file is included implicitly in the compilation of every source file,
24 using -include. It includes config.h. */
26 /* Enable declarations of GNU extensions, since we are compiling them. */
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)
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)
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
47 #if IS_IN (testsuite) || defined IS_IN_build || defined __cplusplus
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. */
59 # define IN_MODULE (-1)
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. */
73 /* Some files must be compiled with optimization on. */
74 #if !defined __ASSEMBLER__ && !defined __OPTIMIZE__
75 # error "glibc cannot be compiled without optimization"
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"
87 /* When PIC is defined and SHARED isn't defined, we are building PIE
89 #if defined PIC && !defined SHARED
90 # define BUILD_PIE_DEFAULT 1
92 # define BUILD_PIE_DEFAULT 0
95 /* Define this for the benefit of portable GNU code that wants to check it.
96 Code that checks with #if will not #include <config.h> again, since we've
97 already done it (and this file is implicitly included in every compile,
98 via -include). Code that checks with #ifdef will #include <config.h>,
99 but that file should always be idempotent (i.e., it's just #define/#undef
100 and nothing else anywhere should be changing the macro state it touches),
102 #define HAVE_CONFIG_H 0
104 /* Define these macros for the benefit of portable GNU code that wants to check
105 them. Of course, STDC_HEADERS is never false when building libc! */
106 #define STDC_HEADERS 1
107 #define HAVE_MBSTATE_T 1
108 #define HAVE_MBSRTOWCS 1
109 #define HAVE_LIBINTL_H 1
110 #define HAVE_WCTYPE_H 1
111 #define HAVE_ISWCTYPE 1
114 /* The symbols in all the user (non-_) macros are C symbols. */
116 #ifndef __SYMBOL_PREFIX
117 # define __SYMBOL_PREFIX
120 #ifndef C_SYMBOL_NAME
121 # define C_SYMBOL_NAME(name) name
125 # define ASM_LINE_SEP ;
128 #ifndef __ASSEMBLER__
129 /* GCC understands weak symbols and aliases; use its interface where
130 possible, instead of embedded assembly language. */
132 /* Define ALIASNAME as a strong alias for NAME. */
133 # define strong_alias(name, aliasname) _strong_alias(name, aliasname)
134 # define _strong_alias(name, aliasname) \
135 extern __typeof (name) aliasname __attribute__ ((alias (#name)));
137 /* This comes between the return type and function name in
138 a function definition to make that definition weak. */
139 # define weak_function __attribute__ ((weak))
140 # define weak_const_function __attribute__ ((weak, __const__))
142 /* Define ALIASNAME as a weak alias for NAME.
143 If weak aliases are not available, this defines a strong alias. */
144 # define weak_alias(name, aliasname) _weak_alias (name, aliasname)
145 # define _weak_alias(name, aliasname) \
146 extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
148 /* Same as WEAK_ALIAS, but mark symbol as hidden. */
149 # define weak_hidden_alias(name, aliasname) \
150 _weak_hidden_alias (name, aliasname)
151 # define _weak_hidden_alias(name, aliasname) \
152 extern __typeof (name) aliasname \
153 __attribute__ ((weak, alias (#name), __visibility__ ("hidden")));
155 /* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */
156 # define weak_extern(symbol) _weak_extern (weak symbol)
157 # define _weak_extern(expr) _Pragma (#expr)
159 /* In shared builds, the expression call_function_static_weak
160 (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
161 identifier) unconditionally, with the (potentially empty) argument
162 list ARGUMENTS. In static builds, if FUNCTION-SYMBOL has a
163 definition, the function is invoked as before; if FUNCTION-SYMBOL
164 is NULL, no call is performed. */
166 # define call_function_static_weak(func, ...) func (__VA_ARGS__)
168 # define call_function_static_weak(func, ...) \
170 extern __typeof__ (func) func weak_function; \
171 (func != NULL ? func (__VA_ARGS__) : (void)0); \
175 #else /* __ASSEMBLER__ */
177 # ifdef HAVE_ASM_SET_DIRECTIVE
178 # define strong_alias(original, alias) \
179 .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
180 .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
181 # define strong_data_alias(original, alias) strong_alias(original, alias)
183 # define strong_alias(original, alias) \
184 .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
185 C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
186 # define strong_data_alias(original, alias) strong_alias(original, alias)
189 # define weak_alias(original, alias) \
190 .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP \
191 C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
193 # define weak_extern(symbol) \
194 .weak C_SYMBOL_NAME (symbol)
196 #endif /* __ASSEMBLER__ */
198 /* Determine the return address. */
199 #define RETURN_ADDRESS(nr) \
200 __builtin_extract_return_addr (__builtin_return_address (nr))
202 /* When a reference to SYMBOL is encountered, the linker will emit a
203 warning message MSG. */
204 /* We want the .gnu.warning.SYMBOL section to be unallocated. */
205 #define __make_section_unallocated(section_string) \
206 asm (".section " section_string "\n\t.previous");
208 /* Tacking on "\n\t#" to the section name makes gcc put it's bogus
209 section attributes on what looks like a comment to the assembler. */
210 #ifdef HAVE_SECTION_QUOTES
211 # define __sec_comment "\"\n\t#\""
213 # define __sec_comment "\n\t#"
215 #define link_warning(symbol, msg) \
216 __make_section_unallocated (".gnu.warning." #symbol) \
217 static const char __evoke_link_warning_##symbol[] \
218 __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
220 #define libc_freeres_ptr(decl) \
221 __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
222 decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
223 #define __libc_freeres_fn_section \
224 __attribute__ ((section ("__libc_freeres_fn")))
226 #define libc_freeres_fn(name) \
227 static void name (void) __attribute_used__ __libc_freeres_fn_section; \
228 text_set_element (__libc_subfreeres, name); \
229 static void name (void)
231 /* A canned warning for sysdeps/stub functions. */
232 #define stub_warning(name) \
233 __make_section_unallocated (".gnu.glibc-stub." #name) \
234 link_warning (name, #name " is not implemented and will always fail")
236 /* Warning for linking functions calling dlopen into static binaries. */
238 #define static_link_warning(name)
240 #define static_link_warning(name) static_link_warning1(name)
241 #define static_link_warning1(name) \
242 link_warning(name, "Using '" #name "' in statically linked applications \
243 requires at runtime the shared libraries from the glibc version used \
247 /* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
248 alias to ORIGINAL, when the assembler supports such declarations
250 This is only necessary when defining something in assembly, or playing
251 funny alias games where the size should be other than what the compiler
253 #define declare_symbol_alias(symbol, original, type, size) \
254 declare_symbol_alias_1 (symbol, original, type, size)
256 # define declare_symbol_alias_1(symbol, original, type, size) \
257 strong_alias (original, symbol); \
258 .type C_SYMBOL_NAME (symbol), %##type; \
259 .size C_SYMBOL_NAME (symbol), size
260 #else /* Not __ASSEMBLER__. */
261 # define declare_symbol_alias_1(symbol, original, type, size) \
262 asm (".globl " __SYMBOL_PREFIX #symbol \
263 "\n\t" declare_symbol_alias_1_alias (symbol, original) \
264 "\n\t.type " __SYMBOL_PREFIX #symbol ", " \
266 "\n\t.size " __SYMBOL_PREFIX #symbol ", " #size);
267 # ifdef HAVE_ASM_SET_DIRECTIVE
268 # define declare_symbol_alias_1_alias(symbol, original) \
269 ".set " __SYMBOL_PREFIX #symbol ", " __SYMBOL_PREFIX #original
271 # define declare_symbol_alias_1_alias(symbol, original) \
272 __SYMBOL_PREFIX #symbol " = " __SYMBOL_PREFIX #original
273 # endif /* HAVE_ASM_SET_DIRECTIVE */
274 #endif /* __ASSEMBLER__ */
281 /* Symbol set support macros. */
283 /* Make SYMBOL, which is in the text segment, an element of SET. */
284 #define text_set_element(set, symbol) _elf_set_element(set, symbol)
285 /* Make SYMBOL, which is in the data segment, an element of SET. */
286 #define data_set_element(set, symbol) _elf_set_element(set, symbol)
287 /* Make SYMBOL, which is in the bss segment, an element of SET. */
288 #define bss_set_element(set, symbol) _elf_set_element(set, symbol)
290 /* These are all done the same way in ELF.
291 There is a new section created for each set. */
293 /* When building a shared library, make the set section writable,
294 because it will need to be relocated at run time anyway. */
295 # define _elf_set_element(set, symbol) \
296 static const void *__elf_set_##set##_element_##symbol##__ \
297 __attribute__ ((used, section (#set))) = &(symbol)
299 # define _elf_set_element(set, symbol) \
300 static const void *const __elf_set_##set##_element_##symbol##__ \
301 __attribute__ ((used, section (#set))) = &(symbol)
304 /* Define SET as a symbol set. This may be required (it is in a.out) to
305 be able to use the set's contents. */
306 #define symbol_set_define(set) symbol_set_declare(set)
308 /* Declare SET for use in this module, if defined in another module.
309 In a shared library, this is always local to that shared object.
310 For static linking, the set might be wholly absent and so we use
312 #define symbol_set_declare(set) \
313 extern char const __start_##set[] __symbol_set_attribute; \
314 extern char const __stop_##set[] __symbol_set_attribute;
316 # define __symbol_set_attribute attribute_hidden
318 # define __symbol_set_attribute __attribute__ ((weak))
321 /* Return a pointer (void *const *) to the first element of SET. */
322 #define symbol_set_first_element(set) ((void *const *) (&__start_##set))
324 /* Return true iff PTR (a void *const *) has been incremented
325 past the last element in SET. */
326 #define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
328 /* Use symbol_version_reference to specify the version a symbol
329 reference should link to. Use symbol_version or
330 default_symbol_version for the definition of a versioned symbol.
331 The difference is that the latter is a no-op in non-shared
334 # define symbol_version_reference(real, name, version) \
335 .symver real, name##@##version
336 #else /* !__ASSEMBLER__ */
337 # define symbol_version_reference(real, name, version) \
338 __asm__ (".symver " #real "," #name "@" #version)
342 # define symbol_version(real, name, version) \
343 symbol_version_reference(real, name, version)
344 # define default_symbol_version(real, name, version) \
345 _default_symbol_version(real, name, version)
346 # ifdef __ASSEMBLER__
347 # define _default_symbol_version(real, name, version) \
348 .symver real, name##@##@##version
350 # define _default_symbol_version(real, name, version) \
351 __asm__ (".symver " #real "," #name "@@" #version)
354 # define symbol_version(real, name, version)
355 # define default_symbol_version(real, name, version) \
356 strong_alias(real, name)
359 #if defined SHARED || defined LIBC_NONSHARED \
360 || (BUILD_PIE_DEFAULT && IS_IN (libc))
361 # define attribute_hidden __attribute__ ((visibility ("hidden")))
363 # define attribute_hidden
366 #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
368 #define attribute_relro __attribute__ ((section (".data.rel.ro")))
371 /* Used to disable stack protection in sensitive places, like ifunc
372 resolvers and early static TLS init. */
373 #ifdef HAVE_CC_NO_STACK_PROTECTOR
374 # define inhibit_stack_protector \
375 __attribute__ ((__optimize__ ("-fno-stack-protector")))
377 # define inhibit_stack_protector
380 /* The following macros are used for PLT bypassing within libc.so
381 (and if needed other libraries similarly).
382 First of all, you need to have the function prototyped somewhere,
387 If calls to foo within libc.so should always go to foo defined in libc.so,
388 then in include/foo.h you add:
390 libc_hidden_proto (foo)
392 line and after the foo function definition:
398 libc_hidden_def (foo)
406 libc_hidden_weak (foo)
408 Similarly for global data. If references to foo within libc.so should
409 always go to foo defined in libc.so, then in include/foo.h you add:
411 libc_hidden_proto (foo)
413 line and after foo's definition:
415 int foo = INITIAL_FOO_VALUE;
416 libc_hidden_data_def (foo)
420 int foo = INITIAL_FOO_VALUE;
421 libc_hidden_data_weak (foo)
423 If foo is normally just an alias (strong or weak) to some other function,
424 you should use the normal strong_alias first, then add libc_hidden_def
431 strong_alias (baz, foo)
432 libc_hidden_weak (foo)
434 If the function should be internal to multiple objects, say ld.so and
435 libc.so, the best way is to use:
437 #if IS_IN (libc) || IS_IN (rtld)
441 in include/foo.h and the normal macros at all function definitions
442 depending on what DSO they belong to.
444 If versioned_symbol macro is used to define foo,
445 libc_hidden_ver macro should be used, as in:
447 int __real_foo (int __bar)
451 versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
452 libc_hidden_ver (__real_foo, foo) */
454 #if defined SHARED && !defined NO_HIDDEN
455 # ifndef __ASSEMBLER__
456 # define __hidden_proto_hiddenattr(attrs...) \
457 __attribute__ ((visibility ("hidden"), ##attrs))
458 # define hidden_proto(name, attrs...) \
459 __hidden_proto (name, , __GI_##name, ##attrs)
460 # define hidden_tls_proto(name, attrs...) \
461 __hidden_proto (name, __thread, __GI_##name, ##attrs)
462 # define __hidden_proto(name, thread, internal, attrs...) \
463 extern thread __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
464 __hidden_proto_hiddenattr (attrs);
465 # define __hidden_asmname(name) \
466 __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
467 # define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
468 # define __hidden_asmname2(prefix, name) #prefix name
469 # define __hidden_ver1(local, internal, name) \
470 extern __typeof (name) __EI_##name __asm__(__hidden_asmname (#internal)); \
471 extern __typeof (name) __EI_##name \
472 __attribute__((alias (__hidden_asmname (#local))))
473 # define hidden_ver(local, name) __hidden_ver1(local, __GI_##name, name);
474 # define hidden_data_ver(local, name) hidden_ver(local, name)
475 # define hidden_def(name) __hidden_ver1(__GI_##name, name, name);
476 # define hidden_data_def(name) hidden_def(name)
477 # define hidden_weak(name) \
478 __hidden_ver1(__GI_##name, name, name) __attribute__((weak));
479 # define hidden_data_weak(name) hidden_weak(name)
480 # define hidden_nolink(name, lib, version) \
481 __hidden_nolink1 (__GI_##name, __EI_##name, name, VERSION_##lib##_##version)
482 # define __hidden_nolink1(local, internal, name, version) \
483 __hidden_nolink2 (local, internal, name, version)
484 # define __hidden_nolink2(local, internal, name, version) \
485 extern __typeof (name) internal __attribute__ ((alias (#local))); \
486 __hidden_nolink3 (local, internal, #name "@" #version)
487 # define __hidden_nolink3(local, internal, vername) \
488 __asm__ (".symver " #internal ", " vername);
490 /* For assembly, we need to do the opposite of what we do in C:
491 in assembly gcc __REDIRECT stuff is not in place, so functions
492 are defined by its normal name and we need to create the
493 __GI_* alias to it, in C __REDIRECT causes the function definition
494 to use __GI_* name and we need to add alias to the real name.
495 There is no reason to use hidden_weak over hidden_def in assembly,
496 but we provide it for consistency with the C usage.
497 hidden_proto doesn't make sense for assembly but the equivalent
498 is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET. */
499 # define hidden_def(name) strong_alias (name, __GI_##name)
500 # define hidden_weak(name) hidden_def (name)
501 # define hidden_ver(local, name) strong_alias (local, __GI_##name)
502 # define hidden_data_def(name) strong_data_alias (name, __GI_##name)
503 # define hidden_data_weak(name) hidden_data_def (name)
504 # define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
505 # define HIDDEN_JUMPTARGET(name) __GI_##name
508 # ifndef __ASSEMBLER__
509 # if !defined SHARED && IS_IN (libc) && !defined LIBC_NONSHARED \
510 && !defined NO_HIDDEN
511 # define __hidden_proto_hiddenattr(attrs...) \
512 __attribute__ ((visibility ("hidden"), ##attrs))
513 # define hidden_proto(name, attrs...) \
514 __hidden_proto (name, , name, ##attrs)
515 # define hidden_tls_proto(name, attrs...) \
516 __hidden_proto (name, __thread, name, ##attrs)
517 # define __hidden_proto(name, thread, internal, attrs...) \
518 extern thread __typeof (name) name __hidden_proto_hiddenattr (attrs);
520 # define hidden_proto(name, attrs...)
521 # define hidden_tls_proto(name, attrs...)
524 # define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
525 # endif /* Not __ASSEMBLER__ */
526 # define hidden_weak(name)
527 # define hidden_def(name)
528 # define hidden_ver(local, name)
529 # define hidden_data_weak(name)
530 # define hidden_data_def(name)
531 # define hidden_data_ver(local, name)
532 # define hidden_nolink(name, lib, version)
536 # define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
537 # define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
538 # define libc_hidden_def(name) hidden_def (name)
539 # define libc_hidden_weak(name) hidden_weak (name)
540 # ifdef LINK_OBSOLETE_RPC
541 /* libc_hidden_nolink_sunrpc should only get used in sunrpc code. */
542 # define libc_hidden_nolink_sunrpc(name, version) hidden_def (name)
544 # define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
546 # define libc_hidden_ver(local, name) hidden_ver (local, name)
547 # define libc_hidden_data_def(name) hidden_data_def (name)
548 # define libc_hidden_data_weak(name) hidden_data_weak (name)
549 # define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
551 # define libc_hidden_proto(name, attrs...)
552 # define libc_hidden_tls_proto(name, attrs...)
553 # define libc_hidden_def(name)
554 # define libc_hidden_weak(name)
555 # define libc_hidden_ver(local, name)
556 # define libc_hidden_data_def(name)
557 # define libc_hidden_data_weak(name)
558 # define libc_hidden_data_ver(local, name)
561 #if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
562 # define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
563 # define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
564 # define rtld_hidden_def(name) hidden_def (name)
565 # define rtld_hidden_weak(name) hidden_weak (name)
566 # define rtld_hidden_ver(local, name) hidden_ver (local, name)
567 # define rtld_hidden_data_def(name) hidden_data_def (name)
568 # define rtld_hidden_data_weak(name) hidden_data_weak (name)
569 # define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
571 # define rtld_hidden_proto(name, attrs...)
572 # define rtld_hidden_tls_proto(name, attrs...)
573 # define rtld_hidden_def(name)
574 # define rtld_hidden_weak(name)
575 # define rtld_hidden_ver(local, name)
576 # define rtld_hidden_data_def(name)
577 # define rtld_hidden_data_weak(name)
578 # define rtld_hidden_data_ver(local, name)
582 # define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
583 # define libm_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
584 # define libm_hidden_def(name) hidden_def (name)
585 # define libm_hidden_weak(name) hidden_weak (name)
586 # define libm_hidden_ver(local, name) hidden_ver (local, name)
587 # define libm_hidden_data_def(name) hidden_data_def (name)
588 # define libm_hidden_data_weak(name) hidden_data_weak (name)
589 # define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
591 # define libm_hidden_proto(name, attrs...)
592 # define libm_hidden_tls_proto(name, attrs...)
593 # define libm_hidden_def(name)
594 # define libm_hidden_weak(name)
595 # define libm_hidden_ver(local, name)
596 # define libm_hidden_data_def(name)
597 # define libm_hidden_data_weak(name)
598 # define libm_hidden_data_ver(local, name)
602 # define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
603 # define libmvec_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
604 # define libmvec_hidden_def(name) hidden_def (name)
605 # define libmvec_hidden_weak(name) hidden_weak (name)
606 # define libmvec_hidden_ver(local, name) hidden_ver (local, name)
607 # define libmvec_hidden_data_def(name) hidden_data_def (name)
608 # define libmvec_hidden_data_weak(name) hidden_data_weak (name)
609 # define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
611 # define libmvec_hidden_proto(name, attrs...)
612 # define libmvec_hidden_tls_proto(name, attrs...)
613 # define libmvec_hidden_def(name)
614 # define libmvec_hidden_weak(name)
615 # define libmvec_hidden_ver(local, name)
616 # define libmvec_hidden_data_def(name)
617 # define libmvec_hidden_data_weak(name)
618 # define libmvec_hidden_data_ver(local, name)
621 #if IS_IN (libresolv)
622 # define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
623 # define libresolv_hidden_tls_proto(name, attrs...) \
624 hidden_tls_proto (name, ##attrs)
625 # define libresolv_hidden_def(name) hidden_def (name)
626 # define libresolv_hidden_weak(name) hidden_weak (name)
627 # define libresolv_hidden_ver(local, name) hidden_ver (local, name)
628 # define libresolv_hidden_data_def(name) hidden_data_def (name)
629 # define libresolv_hidden_data_weak(name) hidden_data_weak (name)
630 # define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
632 # define libresolv_hidden_proto(name, attrs...)
633 # define libresolv_hidden_tls_proto(name, attrs...)
634 # define libresolv_hidden_def(name)
635 # define libresolv_hidden_weak(name)
636 # define libresolv_hidden_ver(local, name)
637 # define libresolv_hidden_data_def(name)
638 # define libresolv_hidden_data_weak(name)
639 # define libresolv_hidden_data_ver(local, name)
643 # define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
644 # define librt_hidden_tls_proto(name, attrs...) \
645 hidden_tls_proto (name, ##attrs)
646 # define librt_hidden_def(name) hidden_def (name)
647 # define librt_hidden_weak(name) hidden_weak (name)
648 # define librt_hidden_ver(local, name) hidden_ver (local, name)
649 # define librt_hidden_data_def(name) hidden_data_def (name)
650 # define librt_hidden_data_weak(name) hidden_data_weak (name)
651 # define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
653 # define librt_hidden_proto(name, attrs...)
654 # define librt_hidden_tls_proto(name, attrs...)
655 # define librt_hidden_def(name)
656 # define librt_hidden_weak(name)
657 # define librt_hidden_ver(local, name)
658 # define librt_hidden_data_def(name)
659 # define librt_hidden_data_weak(name)
660 # define librt_hidden_data_ver(local, name)
664 # define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
665 # define libdl_hidden_tls_proto(name, attrs...) \
666 hidden_tls_proto (name, ##attrs)
667 # define libdl_hidden_def(name) hidden_def (name)
668 # define libdl_hidden_weak(name) hidden_weak (name)
669 # define libdl_hidden_ver(local, name) hidden_ver (local, name)
670 # define libdl_hidden_data_def(name) hidden_data_def (name)
671 # define libdl_hidden_data_weak(name) hidden_data_weak (name)
672 # define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
674 # define libdl_hidden_proto(name, attrs...)
675 # define libdl_hidden_tls_proto(name, attrs...)
676 # define libdl_hidden_def(name)
677 # define libdl_hidden_weak(name)
678 # define libdl_hidden_ver(local, name)
679 # define libdl_hidden_data_def(name)
680 # define libdl_hidden_data_weak(name)
681 # define libdl_hidden_data_ver(local, name)
684 #if IS_IN (libnss_files)
685 # define libnss_files_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
686 # define libnss_files_hidden_tls_proto(name, attrs...) \
687 hidden_tls_proto (name, ##attrs)
688 # define libnss_files_hidden_def(name) hidden_def (name)
689 # define libnss_files_hidden_weak(name) hidden_weak (name)
690 # define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
691 # define libnss_files_hidden_data_def(name) hidden_data_def (name)
692 # define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
693 # define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
695 # define libnss_files_hidden_proto(name, attrs...)
696 # define libnss_files_hidden_tls_proto(name, attrs...)
697 # define libnss_files_hidden_def(name)
698 # define libnss_files_hidden_weak(name)
699 # define libnss_files_hidden_ver(local, name)
700 # define libnss_files_hidden_data_def(name)
701 # define libnss_files_hidden_data_weak(name)
702 # define libnss_files_hidden_data_ver(local, name)
706 # define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
707 # define libnsl_hidden_tls_proto(name, attrs...) \
708 hidden_tls_proto (name, ##attrs)
709 # ifdef LINK_OBSOLETE_NSL
710 /* libnsl_hidden_nolink should only get used in libnsl code. */
711 # define libnsl_hidden_nolink_def(name, version) libnsl_hidden_def (name)
713 # define libnsl_hidden_nolink_def(name, version) hidden_nolink (name, libnsl, version)
715 # define libnsl_hidden_def(name) hidden_def (name)
716 # define libnsl_hidden_weak(name) hidden_weak (name)
717 # define libnsl_hidden_ver(local, name) hidden_ver (local, name)
718 # define libnsl_hidden_data_def(name) hidden_data_def (name)
719 # define libnsl_hidden_data_weak(name) hidden_data_weak (name)
720 # define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
722 # define libnsl_hidden_proto(name, attrs...)
723 # define libnsl_hidden_tls_proto(name, attrs...)
724 # define libnsl_hidden_def(name)
725 # define libnsl_hidden_weak(name)
726 # define libnsl_hidden_ver(local, name)
727 # define libnsl_hidden_data_def(name)
728 # define libnsl_hidden_data_weak(name)
729 # define libnsl_hidden_data_ver(local, name)
732 #if IS_IN (libnss_nisplus)
733 # define libnss_nisplus_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
734 # define libnss_nisplus_hidden_tls_proto(name, attrs...) \
735 hidden_tls_proto (name, ##attrs)
736 # define libnss_nisplus_hidden_def(name) hidden_def (name)
737 # define libnss_nisplus_hidden_weak(name) hidden_weak (name)
738 # define libnss_nisplus_hidden_ver(local, name) hidden_ver (local, name)
739 # define libnss_nisplus_hidden_data_def(name) hidden_data_def (name)
740 # define libnss_nisplus_hidden_data_weak(name) hidden_data_weak (name)
741 # define libnss_nisplus_hidden_data_ver(local, name) hidden_data_ver (local, name)
743 # define libnss_nisplus_hidden_proto(name, attrs...)
744 # define libnss_nisplus_hidden_tls_proto(name, attrs...)
745 # define libnss_nisplus_hidden_def(name)
746 # define libnss_nisplus_hidden_weak(name)
747 # define libnss_nisplus_hidden_ver(local, name)
748 # define libnss_nisplus_hidden_data_def(name)
749 # define libnss_nisplus_hidden_data_weak(name)
750 # define libnss_nisplus_hidden_data_ver(local, name)
753 #define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
754 #define libc_hidden_builtin_def(name) libc_hidden_def (name)
755 #define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
756 #define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
758 # define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
762 # define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
763 # define libutil_hidden_tls_proto(name, attrs...) \
764 hidden_tls_proto (name, ##attrs)
765 # define libutil_hidden_def(name) hidden_def (name)
766 # define libutil_hidden_weak(name) hidden_weak (name)
767 # define libutil_hidden_ver(local, name) hidden_ver (local, name)
768 # define libutil_hidden_data_def(name) hidden_data_def (name)
769 # define libutil_hidden_data_weak(name) hidden_data_weak (name)
770 # define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
772 # define libutil_hidden_proto(name, attrs...)
773 # define libutil_hidden_tls_proto(name, attrs...)
774 # define libutil_hidden_def(name)
775 # define libutil_hidden_weak(name)
776 # define libutil_hidden_ver(local, name)
777 # define libutil_hidden_data_def(name)
778 # define libutil_hidden_data_weak(name)
779 # define libutil_hidden_data_ver(local, name)
782 /* Get some dirty hacks. */
783 #include <symbol-hacks.h>
785 /* Move compatibility symbols out of the way by placing them all in a
787 #ifndef __ASSEMBLER__
788 # define attribute_compat_text_section \
789 __attribute__ ((section (".text.compat")))
790 # define attribute_compat_data_section \
791 __attribute__ ((section (".data.compat")))
793 # define compat_text_section .section ".text.compat", "ax";
794 # define compat_data_section .section ".data.compat", "aw";
797 /* Helper / base macros for indirect function symbols. */
798 #define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \
799 classifier inhibit_stack_protector \
800 __typeof (type_name) *name##_ifunc (arg) \
803 __typeof (type_name) *res = expr; \
807 #ifdef HAVE_GCC_IFUNC
808 # define __ifunc(type_name, name, expr, arg, init) \
809 extern __typeof (type_name) name __attribute__ \
810 ((ifunc (#name "_ifunc"))); \
811 __ifunc_resolver (type_name, name, expr, arg, init, static)
813 # define __ifunc_hidden(type_name, name, expr, arg, init) \
814 __ifunc (type_name, name, expr, arg, init)
816 /* Gcc does not support __attribute__ ((ifunc (...))). Use the old behaviour
817 as fallback. But keep in mind that the debug information for the ifunc
818 resolver functions is not correct. It contains the ifunc'ed function as
819 DW_AT_linkage_name. E.g. lldb uses this field and an inferior function
820 call of the ifunc'ed function will fail due to "no matching function for
821 call to ..." because the ifunc'ed function and the resolver function have
822 different signatures. (Gcc support is disabled at least on a ppc64le
823 Ubuntu 14.04 system.) */
825 # define __ifunc(type_name, name, expr, arg, init) \
826 extern __typeof (type_name) name; \
827 __typeof (type_name) *name##_ifunc (arg) __asm__ (#name); \
828 __ifunc_resolver (type_name, name, expr, arg, init,) \
829 __asm__ (".type " #name ", %gnu_indirect_function");
831 # define __ifunc_hidden(type_name, name, expr, arg, init) \
832 extern __typeof (type_name) __libc_##name; \
833 __ifunc (type_name, __libc_##name, expr, arg, init) \
834 strong_alias (__libc_##name, name);
835 #endif /* !HAVE_GCC_IFUNC */
837 /* The following macros are used for indirect function symbols in libc.so.
838 First of all, you need to have the function prototyped somewhere,
843 If you have an implementation for foo which e.g. uses a special hardware
844 feature which isn't available on all machines where this libc.so will be
845 used but decideable if available at runtime e.g. via hwcaps, you can provide
846 two or multiple implementations of foo:
848 int __foo_default (int __bar)
853 int __foo_special (int __bar)
858 If your function foo has no libc_hidden_proto (foo) defined for PLT
859 bypassing, you can use:
861 #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
863 libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
865 This will define a resolver function for foo which returns __foo_special or
866 __foo_default depending on your specified expression. Please note that you
867 have to define a macro function INIT_ARCH before using libc_ifunc macro as
868 it is called by the resolver function before evaluating the specified
869 expression. In this example it is used to prepare the hwcap variable.
870 The resolver function is assigned to an ifunc'ed symbol foo. Calls to foo
871 from inside or outside of libc.so will be indirected by a PLT call.
873 If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
874 and calls to foo within libc.so should always go to one specific
875 implementation of foo e.g. __foo_default then you have to add:
877 __hidden_ver1 (__foo_default, __GI_foo, __foo_default);
879 or a tweaked definition of libc_hidden_def macro after the __foo_default
880 function definition. Calls to foo within libc.so will always go directly to
881 __foo_default. Calls to foo from outside libc.so will be indirected by a
882 PLT call to ifunc'ed symbol foo which you have to define in a separate
885 #define foo __redirect_foo
889 extern __typeof (__redirect_foo) __foo_default attribute_hidden;
890 extern __typeof (__redirect_foo) __foo_special attribute_hidden;
892 libc_ifunc_redirected (__redirect_foo, foo,
893 (hwcap & HWCAP_SPECIAL)
897 This will define the ifunc'ed symbol foo like above. The redirection of foo
898 in header file is needed to omit an additional defintion of __GI_foo which
899 would end in a linker error while linking libc.so. You have to specify
900 __redirect_foo as first parameter which is used within libc_ifunc_redirected
901 macro in conjunction with typeof to define the ifunc'ed symbol foo.
903 If your function foo has a libc_hidden_proto (foo) defined and calls to foo
904 within or from outside libc.so should go via ifunc'ed symbol, then you have
907 libc_ifunc_hidden (foo, foo,
908 (hwcap & HWCAP_SPECIAL)
911 libc_hidden_def (foo)
913 The first parameter foo of libc_ifunc_hidden macro is used in the same way
914 as for libc_ifunc_redirected macro. */
916 #define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
918 #define libc_ifunc_redirected(redirected_name, name, expr) \
919 __ifunc (redirected_name, name, expr, void, INIT_ARCH)
921 #define libc_ifunc_hidden(redirected_name, name, expr) \
922 __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
924 /* The body of the function is supposed to use __get_cpu_features
925 which will, if necessary, initialize the data first. */
926 #define libm_ifunc_init()
927 #define libm_ifunc(name, expr) \
928 __ifunc (name, name, expr, void, libm_ifunc_init)
930 /* Add the compiler optimization to inhibit loop transformation to library
931 calls. This is used to avoid recursive calls in memset and memmove
932 default implementations. */
933 #ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
934 # define inhibit_loop_to_libcall \
935 __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
937 # define inhibit_loop_to_libcall
940 /* These macros facilitate sharing source files with gnulib.
942 They are here instead of sys/cdefs.h because they should not be
943 used in public header files.
945 Their definitions should be kept consistent with the definitions in
946 gnulib-common.m4, but it is not necessary to cater to old non-GCC
947 compilers, since they will only be used while building glibc itself.
948 (Note that _GNUC_PREREQ cannot be used in this file.) */
950 /* Define as a marker that can be attached to declarations that might not
951 be used. This helps to reduce warnings, such as from
952 GCC -Wunused-parameter. */
953 #if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
954 # define _GL_UNUSED __attribute__ ((__unused__))
959 /* gcc supports the "unused" attribute on possibly unused labels, and
960 g++ has since version 4.5. Note to support C++ as well as C,
961 _GL_UNUSED_LABEL should be used with a trailing ; */
962 #if !defined __cplusplus || __GNUC__ > 4 \
963 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
964 # define _GL_UNUSED_LABEL _GL_UNUSED
966 # define _GL_UNUSED_LABEL
969 /* The __pure__ attribute was added in gcc 2.96. */
970 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
971 # define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
973 # define _GL_ATTRIBUTE_PURE /* empty */
976 /* The __const__ attribute was added in gcc 2.95. */
977 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
978 # define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
980 # define _GL_ATTRIBUTE_CONST /* empty */
983 #endif /* !_ISOMAC */
984 #endif /* libc-symbols.h */