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) 1995-2018 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/* When PIC is defined and SHARED isn't defined, we are building PIE
88 by default. */
89#if defined PIC && !defined SHARED
90# define BUILD_PIE_DEFAULT 1
91#else
92# define BUILD_PIE_DEFAULT 0
93#endif
94
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),
101 so it's harmless. */
102#define HAVE_CONFIG_H 0
103
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
112#define ENABLE_NLS 1
113
114/* The symbols in all the user (non-_) macros are C symbols. */
115
116#ifndef __SYMBOL_PREFIX
117# define __SYMBOL_PREFIX
118#endif
119
120#ifndef C_SYMBOL_NAME
121# define C_SYMBOL_NAME(name) name
122#endif
123
124#ifndef ASM_LINE_SEP
125# define ASM_LINE_SEP ;
126#endif
127
128#ifndef __ASSEMBLER__
129/* GCC understands weak symbols and aliases; use its interface where
130 possible, instead of embedded assembly language. */
131
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)));
136
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__))
141
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)));
147
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")));
154
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)
158
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. */
165# ifdef SHARED
166# define call_function_static_weak(func, ...) func (__VA_ARGS__)
167# else /* !SHARED */
168# define call_function_static_weak(func, ...) \
169 ({ \
170 extern __typeof__ (func) func weak_function; \
171 (func != NULL ? func (__VA_ARGS__) : (void)0); \
172 })
173# endif
174
175#else /* __ASSEMBLER__ */
176
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)
182# else
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)
187# endif
188
189# define weak_alias(original, alias) \
190 .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP \
191 C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
192
193# define weak_extern(symbol) \
194 .weak C_SYMBOL_NAME (symbol)
195
196#endif /* __ASSEMBLER__ */
197
198/* Determine the return address. */
199#define RETURN_ADDRESS(nr) \
200 __builtin_extract_return_addr (__builtin_return_address (nr))
201
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");
207
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#\""
212#else
213# define __sec_comment "\n\t#"
214#endif
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))) \
219 = msg;
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")))
225
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)
230
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")
235
236/* Warning for linking functions calling dlopen into static binaries. */
237#ifdef SHARED
238#define static_link_warning(name)
239#else
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 \
243requires at runtime the shared libraries from the glibc version used \
244for linking")
245#endif
246
247/* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
248 alias to ORIGINAL, when the assembler supports such declarations
249 (such as in ELF).
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
252 thinks it is. */
253#define declare_symbol_alias(symbol, original, type, size) \
254 declare_symbol_alias_1 (symbol, original, type, size)
255#ifdef __ASSEMBLER__
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 ", " \
265 "%" #type \
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
270# else
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__ */
275
276
277/*
278
279*/
280
281/* Symbol set support macros. */
282
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)
289
290/* These are all done the same way in ELF.
291 There is a new section created for each set. */
292#ifdef SHARED
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)
298#else
299# define _elf_set_element(set, symbol) \
300 static const void *const __elf_set_##set##_element_##symbol##__ \
301 __attribute__ ((used, section (#set))) = &(symbol)
302#endif
303
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)
307
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
311 weak references. */
312#define symbol_set_declare(set) \
313 extern char const __start_##set[] __symbol_set_attribute; \
314 extern char const __stop_##set[] __symbol_set_attribute;
315#ifdef SHARED
316# define __symbol_set_attribute attribute_hidden
317#else
318# define __symbol_set_attribute __attribute__ ((weak))
319#endif
320
321/* Return a pointer (void *const *) to the first element of SET. */
322#define symbol_set_first_element(set) ((void *const *) (&__start_##set))
323
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)
327
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
332 builds. */
333#ifdef __ASSEMBLER__
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)
339#endif
340
341#ifdef SHARED
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
349# else
350# define _default_symbol_version(real, name, version) \
351 __asm__ (".symver " #real "," #name "@@" #version)
352# endif
353#else
354# define symbol_version(real, name, version)
355# define default_symbol_version(real, name, version) \
356 strong_alias(real, name)
357#endif
358
359#if defined SHARED || defined LIBC_NONSHARED \
360 || (BUILD_PIE_DEFAULT && IS_IN (libc))
361# define attribute_hidden __attribute__ ((visibility ("hidden")))
362#else
363# define attribute_hidden
364#endif
365
366#define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
367
368#define attribute_relro __attribute__ ((section (".data.rel.ro")))
369
370
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")))
376#else
377# define inhibit_stack_protector
378#endif
379
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,
383 say in foo/foo.h:
384
385 int foo (int __bar);
386
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:
389
390 libc_hidden_proto (foo)
391
392 line and after the foo function definition:
393
394 int foo (int __bar)
395 {
396 return __bar;
397 }
398 libc_hidden_def (foo)
399
400 or
401
402 int foo (int __bar)
403 {
404 return __bar;
405 }
406 libc_hidden_weak (foo)
407
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:
410
411 libc_hidden_proto (foo)
412
413 line and after foo's definition:
414
415 int foo = INITIAL_FOO_VALUE;
416 libc_hidden_data_def (foo)
417
418 or
419
420 int foo = INITIAL_FOO_VALUE;
421 libc_hidden_data_weak (foo)
422
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
425 or libc_hidden_weak:
426
427 int baz (int __bar)
428 {
429 return __bar;
430 }
431 strong_alias (baz, foo)
432 libc_hidden_weak (foo)
433
434 If the function should be internal to multiple objects, say ld.so and
435 libc.so, the best way is to use:
436
437 #if IS_IN (libc) || IS_IN (rtld)
438 hidden_proto (foo)
439 #endif
440
441 in include/foo.h and the normal macros at all function definitions
442 depending on what DSO they belong to.
443
444 If versioned_symbol macro is used to define foo,
445 libc_hidden_ver macro should be used, as in:
446
447 int __real_foo (int __bar)
448 {
449 return __bar;
450 }
451 versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
452 libc_hidden_ver (__real_foo, foo) */
453
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);
489# else
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
506# endif
507#else
508# ifndef __ASSEMBLER__
509# if !defined SHARED && IS_IN (libc) && !defined LIBC_NONSHARED \
510 && (!defined PIC || !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE) \
511 && !defined NO_HIDDEN
512# define __hidden_proto_hiddenattr(attrs...) \
513 __attribute__ ((visibility ("hidden"), ##attrs))
514# define hidden_proto(name, attrs...) \
515 __hidden_proto (name, , name, ##attrs)
516# define hidden_tls_proto(name, attrs...) \
517 __hidden_proto (name, __thread, name, ##attrs)
518# define __hidden_proto(name, thread, internal, attrs...) \
519 extern thread __typeof (name) name __hidden_proto_hiddenattr (attrs);
520# else
521# define hidden_proto(name, attrs...)
522# define hidden_tls_proto(name, attrs...)
523# endif
524# else
525# define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
526# endif /* Not __ASSEMBLER__ */
527# define hidden_weak(name)
528# define hidden_def(name)
529# define hidden_ver(local, name)
530# define hidden_data_weak(name)
531# define hidden_data_def(name)
532# define hidden_data_ver(local, name)
533# define hidden_nolink(name, lib, version)
534#endif
535
536#if IS_IN (libc)
537# define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
538# define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
539# define libc_hidden_def(name) hidden_def (name)
540# define libc_hidden_weak(name) hidden_weak (name)
541# ifdef LINK_OBSOLETE_RPC
542 /* libc_hidden_nolink_sunrpc should only get used in sunrpc code. */
543# define libc_hidden_nolink_sunrpc(name, version) hidden_def (name)
544# else
545# define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
546# endif
547# define libc_hidden_ver(local, name) hidden_ver (local, name)
548# define libc_hidden_data_def(name) hidden_data_def (name)
549# define libc_hidden_data_weak(name) hidden_data_weak (name)
550# define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
551#else
552# define libc_hidden_proto(name, attrs...)
553# define libc_hidden_tls_proto(name, attrs...)
554# define libc_hidden_def(name)
555# define libc_hidden_weak(name)
556# define libc_hidden_ver(local, name)
557# define libc_hidden_data_def(name)
558# define libc_hidden_data_weak(name)
559# define libc_hidden_data_ver(local, name)
560#endif
561
562#if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
563# define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
564# define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
565# define rtld_hidden_def(name) hidden_def (name)
566# define rtld_hidden_weak(name) hidden_weak (name)
567# define rtld_hidden_ver(local, name) hidden_ver (local, name)
568# define rtld_hidden_data_def(name) hidden_data_def (name)
569# define rtld_hidden_data_weak(name) hidden_data_weak (name)
570# define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
571#else
572# define rtld_hidden_proto(name, attrs...)
573# define rtld_hidden_tls_proto(name, attrs...)
574# define rtld_hidden_def(name)
575# define rtld_hidden_weak(name)
576# define rtld_hidden_ver(local, name)
577# define rtld_hidden_data_def(name)
578# define rtld_hidden_data_weak(name)
579# define rtld_hidden_data_ver(local, name)
580#endif
581
582#if IS_IN (libm)
583# define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
584# define libm_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
585# define libm_hidden_def(name) hidden_def (name)
586# define libm_hidden_weak(name) hidden_weak (name)
587# define libm_hidden_ver(local, name) hidden_ver (local, name)
588# define libm_hidden_data_def(name) hidden_data_def (name)
589# define libm_hidden_data_weak(name) hidden_data_weak (name)
590# define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
591#else
592# define libm_hidden_proto(name, attrs...)
593# define libm_hidden_tls_proto(name, attrs...)
594# define libm_hidden_def(name)
595# define libm_hidden_weak(name)
596# define libm_hidden_ver(local, name)
597# define libm_hidden_data_def(name)
598# define libm_hidden_data_weak(name)
599# define libm_hidden_data_ver(local, name)
600#endif
601
602#if IS_IN (libmvec)
603# define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
604# define libmvec_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
605# define libmvec_hidden_def(name) hidden_def (name)
606# define libmvec_hidden_weak(name) hidden_weak (name)
607# define libmvec_hidden_ver(local, name) hidden_ver (local, name)
608# define libmvec_hidden_data_def(name) hidden_data_def (name)
609# define libmvec_hidden_data_weak(name) hidden_data_weak (name)
610# define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
611#else
612# define libmvec_hidden_proto(name, attrs...)
613# define libmvec_hidden_tls_proto(name, attrs...)
614# define libmvec_hidden_def(name)
615# define libmvec_hidden_weak(name)
616# define libmvec_hidden_ver(local, name)
617# define libmvec_hidden_data_def(name)
618# define libmvec_hidden_data_weak(name)
619# define libmvec_hidden_data_ver(local, name)
620#endif
621
622#if IS_IN (libresolv)
623# define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
624# define libresolv_hidden_tls_proto(name, attrs...) \
625 hidden_tls_proto (name, ##attrs)
626# define libresolv_hidden_def(name) hidden_def (name)
627# define libresolv_hidden_weak(name) hidden_weak (name)
628# define libresolv_hidden_ver(local, name) hidden_ver (local, name)
629# define libresolv_hidden_data_def(name) hidden_data_def (name)
630# define libresolv_hidden_data_weak(name) hidden_data_weak (name)
631# define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
632#else
633# define libresolv_hidden_proto(name, attrs...)
634# define libresolv_hidden_tls_proto(name, attrs...)
635# define libresolv_hidden_def(name)
636# define libresolv_hidden_weak(name)
637# define libresolv_hidden_ver(local, name)
638# define libresolv_hidden_data_def(name)
639# define libresolv_hidden_data_weak(name)
640# define libresolv_hidden_data_ver(local, name)
641#endif
642
643#if IS_IN (librt)
644# define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
645# define librt_hidden_tls_proto(name, attrs...) \
646 hidden_tls_proto (name, ##attrs)
647# define librt_hidden_def(name) hidden_def (name)
648# define librt_hidden_weak(name) hidden_weak (name)
649# define librt_hidden_ver(local, name) hidden_ver (local, name)
650# define librt_hidden_data_def(name) hidden_data_def (name)
651# define librt_hidden_data_weak(name) hidden_data_weak (name)
652# define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
653#else
654# define librt_hidden_proto(name, attrs...)
655# define librt_hidden_tls_proto(name, attrs...)
656# define librt_hidden_def(name)
657# define librt_hidden_weak(name)
658# define librt_hidden_ver(local, name)
659# define librt_hidden_data_def(name)
660# define librt_hidden_data_weak(name)
661# define librt_hidden_data_ver(local, name)
662#endif
663
664#if IS_IN (libdl)
665# define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
666# define libdl_hidden_tls_proto(name, attrs...) \
667 hidden_tls_proto (name, ##attrs)
668# define libdl_hidden_def(name) hidden_def (name)
669# define libdl_hidden_weak(name) hidden_weak (name)
670# define libdl_hidden_ver(local, name) hidden_ver (local, name)
671# define libdl_hidden_data_def(name) hidden_data_def (name)
672# define libdl_hidden_data_weak(name) hidden_data_weak (name)
673# define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
674#else
675# define libdl_hidden_proto(name, attrs...)
676# define libdl_hidden_tls_proto(name, attrs...)
677# define libdl_hidden_def(name)
678# define libdl_hidden_weak(name)
679# define libdl_hidden_ver(local, name)
680# define libdl_hidden_data_def(name)
681# define libdl_hidden_data_weak(name)
682# define libdl_hidden_data_ver(local, name)
683#endif
684
685#if IS_IN (libnss_files)
686# define libnss_files_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
687# define libnss_files_hidden_tls_proto(name, attrs...) \
688 hidden_tls_proto (name, ##attrs)
689# define libnss_files_hidden_def(name) hidden_def (name)
690# define libnss_files_hidden_weak(name) hidden_weak (name)
691# define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
692# define libnss_files_hidden_data_def(name) hidden_data_def (name)
693# define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
694# define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
695#else
696# define libnss_files_hidden_proto(name, attrs...)
697# define libnss_files_hidden_tls_proto(name, attrs...)
698# define libnss_files_hidden_def(name)
699# define libnss_files_hidden_weak(name)
700# define libnss_files_hidden_ver(local, name)
701# define libnss_files_hidden_data_def(name)
702# define libnss_files_hidden_data_weak(name)
703# define libnss_files_hidden_data_ver(local, name)
704#endif
705
706#if IS_IN (libnsl)
707# define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
708# define libnsl_hidden_tls_proto(name, attrs...) \
709 hidden_tls_proto (name, ##attrs)
710# ifdef LINK_OBSOLETE_NSL
711 /* libnsl_hidden_nolink should only get used in libnsl code. */
712# define libnsl_hidden_nolink_def(name, version) libnsl_hidden_def (name)
713# else
714# define libnsl_hidden_nolink_def(name, version) hidden_nolink (name, libnsl, version)
715# endif
716# define libnsl_hidden_def(name) hidden_def (name)
717# define libnsl_hidden_weak(name) hidden_weak (name)
718# define libnsl_hidden_ver(local, name) hidden_ver (local, name)
719# define libnsl_hidden_data_def(name) hidden_data_def (name)
720# define libnsl_hidden_data_weak(name) hidden_data_weak (name)
721# define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
722#else
723# define libnsl_hidden_proto(name, attrs...)
724# define libnsl_hidden_tls_proto(name, attrs...)
725# define libnsl_hidden_def(name)
726# define libnsl_hidden_weak(name)
727# define libnsl_hidden_ver(local, name)
728# define libnsl_hidden_data_def(name)
729# define libnsl_hidden_data_weak(name)
730# define libnsl_hidden_data_ver(local, name)
731#endif
732
733#if IS_IN (libnss_nisplus)
734# define libnss_nisplus_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
735# define libnss_nisplus_hidden_tls_proto(name, attrs...) \
736 hidden_tls_proto (name, ##attrs)
737# define libnss_nisplus_hidden_def(name) hidden_def (name)
738# define libnss_nisplus_hidden_weak(name) hidden_weak (name)
739# define libnss_nisplus_hidden_ver(local, name) hidden_ver (local, name)
740# define libnss_nisplus_hidden_data_def(name) hidden_data_def (name)
741# define libnss_nisplus_hidden_data_weak(name) hidden_data_weak (name)
742# define libnss_nisplus_hidden_data_ver(local, name) hidden_data_ver (local, name)
743#else
744# define libnss_nisplus_hidden_proto(name, attrs...)
745# define libnss_nisplus_hidden_tls_proto(name, attrs...)
746# define libnss_nisplus_hidden_def(name)
747# define libnss_nisplus_hidden_weak(name)
748# define libnss_nisplus_hidden_ver(local, name)
749# define libnss_nisplus_hidden_data_def(name)
750# define libnss_nisplus_hidden_data_weak(name)
751# define libnss_nisplus_hidden_data_ver(local, name)
752#endif
753
754#define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
755#define libc_hidden_builtin_def(name) libc_hidden_def (name)
756#define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
757#define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
758#ifdef __ASSEMBLER__
759# define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
760#endif
761
762#if IS_IN (libutil)
763# define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
764# define libutil_hidden_tls_proto(name, attrs...) \
765 hidden_tls_proto (name, ##attrs)
766# define libutil_hidden_def(name) hidden_def (name)
767# define libutil_hidden_weak(name) hidden_weak (name)
768# define libutil_hidden_ver(local, name) hidden_ver (local, name)
769# define libutil_hidden_data_def(name) hidden_data_def (name)
770# define libutil_hidden_data_weak(name) hidden_data_weak (name)
771# define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
772#else
773# define libutil_hidden_proto(name, attrs...)
774# define libutil_hidden_tls_proto(name, attrs...)
775# define libutil_hidden_def(name)
776# define libutil_hidden_weak(name)
777# define libutil_hidden_ver(local, name)
778# define libutil_hidden_data_def(name)
779# define libutil_hidden_data_weak(name)
780# define libutil_hidden_data_ver(local, name)
781#endif
782
783/* Get some dirty hacks. */
784#include <symbol-hacks.h>
785
786/* Move compatibility symbols out of the way by placing them all in a
787 special section. */
788#ifndef __ASSEMBLER__
789# define attribute_compat_text_section \
790 __attribute__ ((section (".text.compat")))
791# define attribute_compat_data_section \
792 __attribute__ ((section (".data.compat")))
793#else
794# define compat_text_section .section ".text.compat", "ax";
795# define compat_data_section .section ".data.compat", "aw";
796#endif
797
798/* Helper / base macros for indirect function symbols. */
799#define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \
800 classifier inhibit_stack_protector \
801 __typeof (type_name) *name##_ifunc (arg) \
802 { \
803 init (); \
804 __typeof (type_name) *res = expr; \
805 return res; \
806 }
807
808#ifdef HAVE_GCC_IFUNC
809# define __ifunc(type_name, name, expr, arg, init) \
810 extern __typeof (type_name) name __attribute__ \
811 ((ifunc (#name "_ifunc"))); \
812 __ifunc_resolver (type_name, name, expr, arg, init, static)
813
814# define __ifunc_hidden(type_name, name, expr, arg, init) \
815 __ifunc (type_name, name, expr, arg, init)
816#else
817/* Gcc does not support __attribute__ ((ifunc (...))). Use the old behaviour
818 as fallback. But keep in mind that the debug information for the ifunc
819 resolver functions is not correct. It contains the ifunc'ed function as
820 DW_AT_linkage_name. E.g. lldb uses this field and an inferior function
821 call of the ifunc'ed function will fail due to "no matching function for
822 call to ..." because the ifunc'ed function and the resolver function have
823 different signatures. (Gcc support is disabled at least on a ppc64le
824 Ubuntu 14.04 system.) */
825
826# define __ifunc(type_name, name, expr, arg, init) \
827 extern __typeof (type_name) name; \
828 __typeof (type_name) *name##_ifunc (arg) __asm__ (#name); \
829 __ifunc_resolver (type_name, name, expr, arg, init,) \
830 __asm__ (".type " #name ", %gnu_indirect_function");
831
832# define __ifunc_hidden(type_name, name, expr, arg, init) \
833 extern __typeof (type_name) __libc_##name; \
834 __ifunc (type_name, __libc_##name, expr, arg, init) \
835 strong_alias (__libc_##name, name);
836#endif /* !HAVE_GCC_IFUNC */
837
838/* The following macros are used for indirect function symbols in libc.so.
839 First of all, you need to have the function prototyped somewhere,
840 say in foo.h:
841
842 int foo (int __bar);
843
844 If you have an implementation for foo which e.g. uses a special hardware
845 feature which isn't available on all machines where this libc.so will be
846 used but decideable if available at runtime e.g. via hwcaps, you can provide
847 two or multiple implementations of foo:
848
849 int __foo_default (int __bar)
850 {
851 return __bar;
852 }
853
854 int __foo_special (int __bar)
855 {
856 return __bar;
857 }
858
859 If your function foo has no libc_hidden_proto (foo) defined for PLT
860 bypassing, you can use:
861
862 #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
863
864 libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
865
866 This will define a resolver function for foo which returns __foo_special or
867 __foo_default depending on your specified expression. Please note that you
868 have to define a macro function INIT_ARCH before using libc_ifunc macro as
869 it is called by the resolver function before evaluating the specified
870 expression. In this example it is used to prepare the hwcap variable.
871 The resolver function is assigned to an ifunc'ed symbol foo. Calls to foo
872 from inside or outside of libc.so will be indirected by a PLT call.
873
874 If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
875 and calls to foo within libc.so should always go to one specific
876 implementation of foo e.g. __foo_default then you have to add:
877
878 __hidden_ver1 (__foo_default, __GI_foo, __foo_default);
879
880 or a tweaked definition of libc_hidden_def macro after the __foo_default
881 function definition. Calls to foo within libc.so will always go directly to
882 __foo_default. Calls to foo from outside libc.so will be indirected by a
883 PLT call to ifunc'ed symbol foo which you have to define in a separate
884 compile unit:
885
886 #define foo __redirect_foo
887 #include <foo.h>
888 #undef foo
889
890 extern __typeof (__redirect_foo) __foo_default attribute_hidden;
891 extern __typeof (__redirect_foo) __foo_special attribute_hidden;
892
893 libc_ifunc_redirected (__redirect_foo, foo,
894 (hwcap & HWCAP_SPECIAL)
895 ? __foo_special
896 : __foo_default);
897
898 This will define the ifunc'ed symbol foo like above. The redirection of foo
899 in header file is needed to omit an additional defintion of __GI_foo which
900 would end in a linker error while linking libc.so. You have to specify
901 __redirect_foo as first parameter which is used within libc_ifunc_redirected
902 macro in conjunction with typeof to define the ifunc'ed symbol foo.
903
904 If your function foo has a libc_hidden_proto (foo) defined and calls to foo
905 within or from outside libc.so should go via ifunc'ed symbol, then you have
906 to use:
907
908 libc_ifunc_hidden (foo, foo,
909 (hwcap & HWCAP_SPECIAL)
910 ? __foo_special
911 : __foo_default);
912 libc_hidden_def (foo)
913
914 The first parameter foo of libc_ifunc_hidden macro is used in the same way
915 as for libc_ifunc_redirected macro. */
916
917#define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
918
919#define libc_ifunc_redirected(redirected_name, name, expr) \
920 __ifunc (redirected_name, name, expr, void, INIT_ARCH)
921
922#define libc_ifunc_hidden(redirected_name, name, expr) \
923 __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
924
925/* The body of the function is supposed to use __get_cpu_features
926 which will, if necessary, initialize the data first. */
927#define libm_ifunc_init()
928#define libm_ifunc(name, expr) \
929 __ifunc (name, name, expr, void, libm_ifunc_init)
930
931/* Add the compiler optimization to inhibit loop transformation to library
932 calls. This is used to avoid recursive calls in memset and memmove
933 default implementations. */
934#ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
935# define inhibit_loop_to_libcall \
936 __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
937#else
938# define inhibit_loop_to_libcall
939#endif
940
941/* These macros facilitate sharing source files with gnulib.
942
943 They are here instead of sys/cdefs.h because they should not be
944 used in public header files.
945
946 Their definitions should be kept consistent with the definitions in
947 gnulib-common.m4, but it is not necessary to cater to old non-GCC
948 compilers, since they will only be used while building glibc itself.
949 (Note that _GNUC_PREREQ cannot be used in this file.) */
950
951/* Define as a marker that can be attached to declarations that might not
952 be used. This helps to reduce warnings, such as from
953 GCC -Wunused-parameter. */
954#if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
955# define _GL_UNUSED __attribute__ ((__unused__))
956#else
957# define _GL_UNUSED
958#endif
959
960/* gcc supports the "unused" attribute on possibly unused labels, and
961 g++ has since version 4.5. Note to support C++ as well as C,
962 _GL_UNUSED_LABEL should be used with a trailing ; */
963#if !defined __cplusplus || __GNUC__ > 4 \
964 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
965# define _GL_UNUSED_LABEL _GL_UNUSED
966#else
967# define _GL_UNUSED_LABEL
968#endif
969
970/* The __pure__ attribute was added in gcc 2.96. */
971#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
972# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
973#else
974# define _GL_ATTRIBUTE_PURE /* empty */
975#endif
976
977/* The __const__ attribute was added in gcc 2.95. */
978#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
979# define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
980#else
981# define _GL_ATTRIBUTE_CONST /* empty */
982#endif
983
984#endif /* !_ISOMAC */
985#endif /* libc-symbols.h */
986