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) 1995-2022 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 <https://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/* Obtain the definition of symbol_version_reference. */
88#include <libc-symver.h>
89
90/* When PIC is defined and SHARED isn't defined, we are building PIE
91 by default. */
92#if defined PIC && !defined SHARED
93# define BUILD_PIE_DEFAULT 1
94#else
95# define BUILD_PIE_DEFAULT 0
96#endif
97
98/* Define this for the benefit of portable GNU code that wants to check it.
99 Code that checks with #if will not #include <config.h> again, since we've
100 already done it (and this file is implicitly included in every compile,
101 via -include). Code that checks with #ifdef will #include <config.h>,
102 but that file should always be idempotent (i.e., it's just #define/#undef
103 and nothing else anywhere should be changing the macro state it touches),
104 so it's harmless. */
105#define HAVE_CONFIG_H 0
106
107/* Define these macros for the benefit of portable GNU code that wants to check
108 them. Of course, STDC_HEADERS is never false when building libc! */
109#define STDC_HEADERS 1
110#define HAVE_MBSTATE_T 1
111#define HAVE_MBSRTOWCS 1
112#define HAVE_LIBINTL_H 1
113#define HAVE_WCTYPE_H 1
114#define HAVE_ISWCTYPE 1
115#define ENABLE_NLS 1
116
117/* The symbols in all the user (non-_) macros are C symbols. */
118
119#ifndef __SYMBOL_PREFIX
120# define __SYMBOL_PREFIX
121#endif
122
123#ifndef C_SYMBOL_NAME
124# define C_SYMBOL_NAME(name) name
125#endif
126
127#ifndef ASM_LINE_SEP
128# define ASM_LINE_SEP ;
129#endif
130
131#ifndef __attribute_copy__
132/* Provide an empty definition when cdefs.h is not included. */
133# define __attribute_copy__(arg)
134#endif
135
136#ifndef __ASSEMBLER__
137/* GCC understands weak symbols and aliases; use its interface where
138 possible, instead of embedded assembly language. */
139
140/* Define ALIASNAME as a strong alias for NAME. */
141# define strong_alias(name, aliasname) _strong_alias(name, aliasname)
142# define _strong_alias(name, aliasname) \
143 extern __typeof (name) aliasname __attribute__ ((alias (#name))) \
144 __attribute_copy__ (name);
145
146/* This comes between the return type and function name in
147 a function definition to make that definition weak. */
148# define weak_function __attribute__ ((weak))
149# define weak_const_function __attribute__ ((weak, __const__))
150
151/* Define ALIASNAME as a weak alias for NAME.
152 If weak aliases are not available, this defines a strong alias. */
153# define weak_alias(name, aliasname) _weak_alias (name, aliasname)
154# define _weak_alias(name, aliasname) \
155 extern __typeof (name) aliasname __attribute__ ((weak, alias (#name))) \
156 __attribute_copy__ (name);
157
158/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */
159# define weak_extern(symbol) _weak_extern (weak symbol)
160# define _weak_extern(expr) _Pragma (#expr)
161
162/* In shared builds, the expression call_function_static_weak
163 (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
164 identifier) unconditionally, with the (potentially empty) argument
165 list ARGUMENTS. In static builds, if FUNCTION-SYMBOL has a
166 definition, the function is invoked as before; if FUNCTION-SYMBOL
167 is NULL, no call is performed. */
168# ifdef SHARED
169# define call_function_static_weak(func, ...) func (__VA_ARGS__)
170# else /* !SHARED */
171# define call_function_static_weak(func, ...) \
172 ({ \
173 extern __typeof__ (func) func weak_function; \
174 (func != NULL ? func (__VA_ARGS__) : (void)0); \
175 })
176# endif
177
178#else /* __ASSEMBLER__ */
179
180# ifdef HAVE_ASM_SET_DIRECTIVE
181# define strong_alias(original, alias) \
182 .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
183 .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
184# define strong_data_alias(original, alias) strong_alias(original, alias)
185# else
186# define strong_alias(original, alias) \
187 .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
188 C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
189# define strong_data_alias(original, alias) strong_alias(original, alias)
190# endif
191
192# define weak_alias(original, alias) \
193 .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP \
194 C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
195
196# define weak_extern(symbol) \
197 .weak C_SYMBOL_NAME (symbol)
198
199#endif /* __ASSEMBLER__ */
200
201/* Determine the return address. */
202#define RETURN_ADDRESS(nr) \
203 __builtin_extract_return_addr (__builtin_return_address (nr))
204
205/* When a reference to SYMBOL is encountered, the linker will emit a
206 warning message MSG. */
207/* We want the .gnu.warning.SYMBOL section to be unallocated. */
208#define __make_section_unallocated(section_string) \
209 asm (".section " section_string "\n\t.previous");
210
211/* Tacking on "\n\t#" to the section name makes gcc put it's bogus
212 section attributes on what looks like a comment to the assembler. */
213#ifdef HAVE_SECTION_QUOTES
214# define __sec_comment "\"\n\t#\""
215#else
216# define __sec_comment "\n\t#"
217#endif
218#define link_warning(symbol, msg) \
219 __make_section_unallocated (".gnu.warning." #symbol) \
220 static const char __evoke_link_warning_##symbol[] \
221 __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
222 = msg;
223
224/* A canned warning for sysdeps/stub functions. */
225#define stub_warning(name) \
226 __make_section_unallocated (".gnu.glibc-stub." #name) \
227 link_warning (name, #name " is not implemented and will always fail")
228
229/* Warning for linking functions calling dlopen into static binaries. */
230#ifdef SHARED
231#define static_link_warning(name)
232#else
233#define static_link_warning(name) static_link_warning1(name)
234#define static_link_warning1(name) \
235 link_warning(name, "Using '" #name "' in statically linked applications \
236requires at runtime the shared libraries from the glibc version used \
237for linking")
238#endif
239
240/* Resource Freeing Hooks:
241
242 Normally a process exits and the OS cleans up any allocated
243 memory. However, when tooling like mtrace or valgrind is monitoring
244 the process we need to free all resources that are part of the
245 process in order to provide the consistency required to track
246 memory leaks.
247
248 A single public API exists and is __libc_freeres(), and this is used
249 by applications like valgrind to freee resouces.
250
251 There are 3 cases:
252
253 (a) __libc_freeres
254
255 In this case all you need to do is define the freeing routine:
256
257 foo.c:
258 libfoo_freeres_fn (foo_freeres)
259 {
260 complex_free (mem);
261 }
262
263 This ensures the function is called at the right point to free
264 resources.
265
266 (b) __libc_freeres_ptr
267
268 The framework for (a) iterates over the list of pointers-to-free
269 in (b) and frees them.
270
271 foo.c:
272 libc_freeres_ptr (static char *foo_buffer);
273
274 Freeing these resources alaways happens last and is equivalent
275 to registering a function that does 'free (foo_buffer)'.
276
277 (c) Explicit lists of free routines to call or objects to free.
278
279 It is the intended goal to remove (a) and (b) which have some
280 non-determinism based on link order, and instead use explicit
281 lists of functions and frees to resolve cleanup ordering issues
282 and make it easy to debug and maintain.
283
284 As of today the following subsystems use (c):
285
286 Per-thread cleanup:
287 * malloc/thread-freeres.c
288
289 libdl cleanup:
290 * dlfcn/dlfreeres.c
291
292 libpthread cleanup:
293 * nptl/nptlfreeres.c
294
295 So if you need any shutdown routines to run you should add them
296 directly to the appropriate subsystem's shutdown list. */
297
298/* Resource pointers to free in libc.so. */
299#define libc_freeres_ptr(decl) \
300 __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
301 decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
302
303/* Resource freeing functions from libc.so go in this section. */
304#define __libc_freeres_fn_section \
305 __attribute__ ((__used__, section ("__libc_freeres_fn")))
306
307/* Resource freeing functions for libc.so. */
308#define libc_freeres_fn(name) \
309 static void name (void) __attribute_used__ __libc_freeres_fn_section; \
310 text_set_element (__libc_subfreeres, name); \
311 static void name (void)
312
313/* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
314 alias to ORIGINAL, when the assembler supports such declarations
315 (such as in ELF).
316 This is only necessary when defining something in assembly, or playing
317 funny alias games where the size should be other than what the compiler
318 thinks it is. */
319#ifdef __ASSEMBLER__
320# define declare_object_symbol_alias(symbol, original, size) \
321 declare_object_symbol_alias_1 (symbol, original, size)
322# define declare_object_symbol_alias_1(symbol, original, s_size) \
323 strong_alias (original, symbol) ASM_LINE_SEP \
324 .type C_SYMBOL_NAME (symbol), %object ASM_LINE_SEP \
325 .size C_SYMBOL_NAME (symbol), s_size ASM_LINE_SEP
326#else /* Not __ASSEMBLER__. */
327# ifdef HAVE_ASM_SET_DIRECTIVE
328# define declare_symbol_alias_1_alias(symbol, original) \
329 ".set " __SYMBOL_PREFIX #symbol ", " __SYMBOL_PREFIX #original
330# else
331# define declare_symbol_alias_1_alias(symbol, original) \
332 __SYMBOL_PREFIX #symbol " = " __SYMBOL_PREFIX #original
333# endif /* HAVE_ASM_SET_DIRECTIVE */
334#endif /* __ASSEMBLER__ */
335
336
337/*
338
339*/
340
341#ifdef HAVE_GNU_RETAIN
342# define attribute_used_retain __attribute__ ((__used__, __retain__))
343#else
344# define attribute_used_retain __attribute__ ((__used__))
345#endif
346
347/* Symbol set support macros. */
348
349/* Make SYMBOL, which is in the text segment, an element of SET. */
350#define text_set_element(set, symbol) _elf_set_element(set, symbol)
351/* Make SYMBOL, which is in the data segment, an element of SET. */
352#define data_set_element(set, symbol) _elf_set_element(set, symbol)
353/* Make SYMBOL, which is in the bss segment, an element of SET. */
354#define bss_set_element(set, symbol) _elf_set_element(set, symbol)
355
356/* These are all done the same way in ELF.
357 There is a new section created for each set. */
358#ifdef SHARED
359/* When building a shared library, make the set section writable,
360 because it will need to be relocated at run time anyway. */
361# define _elf_set_element(set, symbol) \
362 static const void *__elf_set_##set##_element_##symbol##__ \
363 attribute_used_retain __attribute__ ((section (#set))) = &(symbol)
364#else
365# define _elf_set_element(set, symbol) \
366 static const void *const __elf_set_##set##_element_##symbol##__ \
367 attribute_used_retain __attribute__ ((section (#set))) = &(symbol)
368#endif
369
370/* Define SET as a symbol set. This may be required (it is in a.out) to
371 be able to use the set's contents. */
372#define symbol_set_define(set) symbol_set_declare(set)
373
374/* Declare SET for use in this module, if defined in another module.
375 In a shared library, this is always local to that shared object.
376 For static linking, the set might be wholly absent and so we use
377 weak references. */
378#define symbol_set_declare(set) \
379 extern char const __start_##set[] __symbol_set_attribute; \
380 extern char const __stop_##set[] __symbol_set_attribute;
381#ifdef SHARED
382# define __symbol_set_attribute attribute_hidden
383#else
384# define __symbol_set_attribute __attribute__ ((weak))
385#endif
386
387/* Return a pointer (void *const *) to the first element of SET. */
388#define symbol_set_first_element(set) ((void *const *) (&__start_##set))
389
390/* Return true iff PTR (a void *const *) has been incremented
391 past the last element in SET. */
392#define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
393
394#ifdef SHARED
395# define symbol_version(real, name, version) \
396 symbol_version_reference(real, name, version)
397# define default_symbol_version(real, name, version) \
398 _default_symbol_version(real, name, version)
399/* See <libc-symver.h>. */
400# ifdef __ASSEMBLER__
401# define _default_symbol_version(real, name, version) \
402 _set_symbol_version (real, name@@version)
403# else
404# define _default_symbol_version(real, name, version) \
405 _set_symbol_version (real, #name "@@" #version)
406# endif
407
408/* Evalutes to a string literal for VERSION in LIB. */
409# define symbol_version_string(lib, version) \
410 _symbol_version_stringify_1 (VERSION_##lib##_##version)
411# define _symbol_version_stringify_1(arg) _symbol_version_stringify_2 (arg)
412# define _symbol_version_stringify_2(arg) #arg
413
414#else /* !SHARED */
415# define symbol_version(real, name, version)
416# define default_symbol_version(real, name, version) \
417 strong_alias(real, name)
418#endif
419
420#if defined SHARED || defined LIBC_NONSHARED \
421 || (BUILD_PIE_DEFAULT && IS_IN (libc))
422# define attribute_hidden __attribute__ ((visibility ("hidden")))
423#else
424# define attribute_hidden
425#endif
426
427#define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
428
429#define attribute_relro __attribute__ ((section (".data.rel.ro")))
430
431
432/* Used to disable stack protection in sensitive places, like ifunc
433 resolvers and early static TLS init. */
434#ifdef HAVE_CC_NO_STACK_PROTECTOR
435# define inhibit_stack_protector \
436 __attribute__ ((__optimize__ ("-fno-stack-protector")))
437#else
438# define inhibit_stack_protector
439#endif
440
441/* The following macros are used for PLT bypassing within libc.so
442 (and if needed other libraries similarly).
443 First of all, you need to have the function prototyped somewhere,
444 say in foo/foo.h:
445
446 int foo (int __bar);
447
448 If calls to foo within libc.so should always go to foo defined in libc.so,
449 then in include/foo.h you add:
450
451 libc_hidden_proto (foo)
452
453 line and after the foo function definition:
454
455 int foo (int __bar)
456 {
457 return __bar;
458 }
459 libc_hidden_def (foo)
460
461 or
462
463 int foo (int __bar)
464 {
465 return __bar;
466 }
467 libc_hidden_weak (foo)
468
469 Similarly for global data. If references to foo within libc.so should
470 always go to foo defined in libc.so, then in include/foo.h you add:
471
472 libc_hidden_proto (foo)
473
474 line and after foo's definition:
475
476 int foo = INITIAL_FOO_VALUE;
477 libc_hidden_data_def (foo)
478
479 or
480
481 int foo = INITIAL_FOO_VALUE;
482 libc_hidden_data_weak (foo)
483
484 If foo is normally just an alias (strong or weak) to some other function,
485 you should use the normal strong_alias first, then add libc_hidden_def
486 or libc_hidden_weak:
487
488 int baz (int __bar)
489 {
490 return __bar;
491 }
492 strong_alias (baz, foo)
493 libc_hidden_weak (foo)
494
495 If the function should be internal to multiple objects, say ld.so and
496 libc.so, the best way is to use:
497
498 #if IS_IN (libc) || IS_IN (rtld)
499 hidden_proto (foo)
500 #endif
501
502 in include/foo.h and the normal macros at all function definitions
503 depending on what DSO they belong to.
504
505 If versioned_symbol macro is used to define foo,
506 libc_hidden_ver macro should be used, as in:
507
508 int __real_foo (int __bar)
509 {
510 return __bar;
511 }
512 versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
513 libc_hidden_ver (__real_foo, foo) */
514
515#if defined SHARED && !defined NO_HIDDEN
516# ifndef __ASSEMBLER__
517# define __hidden_proto_hiddenattr(attrs...) \
518 __attribute__ ((visibility ("hidden"), ##attrs))
519# define hidden_proto(name, attrs...) \
520 __hidden_proto (name, , __GI_##name, ##attrs)
521# define hidden_proto_alias(name, alias, attrs...) \
522 __hidden_proto_alias (name, , alias, ##attrs)
523# define hidden_tls_proto(name, attrs...) \
524 __hidden_proto (name, __thread, __GI_##name, ##attrs)
525# define __hidden_proto(name, thread, internal, attrs...) \
526 extern thread __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
527 __hidden_proto_hiddenattr (attrs);
528# define __hidden_proto_alias(name, thread, internal, attrs...) \
529 extern thread __typeof (name) internal __hidden_proto_hiddenattr (attrs);
530# define __hidden_asmname(name) \
531 __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
532# define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
533# define __hidden_asmname2(prefix, name) #prefix name
534# define __hidden_ver1(local, internal, name) \
535 __hidden_ver2 (, local, internal, name)
536# define __hidden_ver2(thread, local, internal, name) \
537 extern thread __typeof (name) __EI_##name \
538 __asm__(__hidden_asmname (#internal)); \
539 extern thread __typeof (name) __EI_##name \
540 __attribute__((alias (__hidden_asmname (#local)))) \
541 __attribute_copy__ (name)
542# define hidden_ver(local, name) __hidden_ver1(local, __GI_##name, name);
543# define hidden_def(name) __hidden_ver1(__GI_##name, name, name);
544# define hidden_def_alias(name, internal) \
545 strong_alias (name, internal)
546# define hidden_data_def(name) hidden_def(name)
547# define hidden_data_def_alias(name, alias) hidden_def_alias(name, alias)
548# define hidden_tls_def(name) \
549 __hidden_ver2 (__thread, __GI_##name, name, name);
550# define hidden_weak(name) \
551 __hidden_ver1(__GI_##name, name, name) __attribute__((weak));
552# define hidden_data_weak(name) hidden_weak(name)
553# define hidden_nolink(name, lib, version) \
554 __hidden_nolink1 (__GI_##name, __EI_##name, name, VERSION_##lib##_##version)
555# define __hidden_nolink1(local, internal, name, version) \
556 __hidden_nolink2 (local, internal, name, version)
557# define __hidden_nolink2(local, internal, name, version) \
558 extern __typeof (name) internal __attribute__ ((alias (#local))) \
559 __attribute_copy__ (name); \
560 __hidden_nolink3 (local, internal, #name "@" #version)
561# define __hidden_nolink3(local, internal, vername) \
562 __asm__ (".symver " #internal ", " vername);
563# else
564/* For assembly, we need to do the opposite of what we do in C:
565 in assembly gcc __REDIRECT stuff is not in place, so functions
566 are defined by its normal name and we need to create the
567 __GI_* alias to it, in C __REDIRECT causes the function definition
568 to use __GI_* name and we need to add alias to the real name.
569 There is no reason to use hidden_weak over hidden_def in assembly,
570 but we provide it for consistency with the C usage.
571 hidden_proto doesn't make sense for assembly but the equivalent
572 is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET. */
573# define hidden_def(name) strong_alias (name, __GI_##name)
574# define hidden_def_alias(name, alias) strong_alias (name, alias)
575# define hidden_weak(name) hidden_def (name)
576# define hidden_ver(local, name) strong_alias (local, __GI_##name)
577# define hidden_data_def(name) strong_data_alias (name, __GI_##name)
578# define hidden_data_def_alias(name, alias) strong_data_alias (name, alias)
579# define hidden_tls_def(name) hidden_data_def (name)
580# define hidden_data_weak(name) hidden_data_def (name)
581# define HIDDEN_JUMPTARGET(name) __GI_##name
582# endif
583#else
584# ifndef __ASSEMBLER__
585# if !defined SHARED && IS_IN (libc) && !defined LIBC_NONSHARED \
586 && (!defined PIC || !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE) \
587 && !defined NO_HIDDEN
588# define __hidden_proto_hiddenattr(attrs...) \
589 __attribute__ ((visibility ("hidden"), ##attrs))
590# define hidden_proto(name, attrs...) \
591 __hidden_proto (name, , name, ##attrs)
592# define hidden_proto_alias(name, alias, attrs...) \
593 __hidden_proto_alias (name, , alias, ##attrs)
594# define hidden_tls_proto(name, attrs...) \
595 __hidden_proto (name, __thread, name, ##attrs)
596# define __hidden_proto(name, thread, internal, attrs...) \
597 extern thread __typeof (name) name __hidden_proto_hiddenattr (attrs);
598# define __hidden_proto_alias(name, thread, internal, attrs...) \
599 extern thread __typeof (name) internal __hidden_proto_hiddenattr (attrs);
600# else
601# define hidden_proto(name, attrs...)
602# define hidden_proto_alias(name, alias, attrs...)
603# define hidden_tls_proto(name, attrs...)
604# endif
605# else
606# define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
607# endif /* Not __ASSEMBLER__ */
608# define hidden_weak(name)
609# define hidden_def(name)
610# define hidden_def_alias(name, alias)
611# define hidden_ver(local, name)
612# define hidden_data_weak(name)
613# define hidden_data_def(name)
614# define hidden_data_def_alias(name, alias)
615# define hidden_tls_def(name)
616# define hidden_nolink(name, lib, version)
617#endif
618
619#if IS_IN (libc)
620# define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
621# define libc_hidden_proto_alias(name, alias, attrs...) \
622 hidden_proto_alias (name, alias, ##attrs)
623# define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
624# define libc_hidden_def(name) hidden_def (name)
625# define libc_hidden_weak(name) hidden_weak (name)
626# define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
627# define libc_hidden_ver(local, name) hidden_ver (local, name)
628# define libc_hidden_data_def(name) hidden_data_def (name)
629# define libc_hidden_data_def_alias(name, alias) hidden_data_def_alias (name, alias)
630# define libc_hidden_tls_def(name) hidden_tls_def (name)
631# define libc_hidden_data_weak(name) hidden_data_weak (name)
632#else
633# define libc_hidden_proto(name, attrs...)
634# define libc_hidden_proto_alias(name, alias, attrs...)
635# define libc_hidden_tls_proto(name, attrs...)
636# define libc_hidden_def(name)
637# define libc_hidden_weak(name)
638# define libc_hidden_ver(local, name)
639# define libc_hidden_data_def(name)
640# define libc_hidden_data_def_alias(name, alias)
641# define libc_hidden_tls_def(name)
642# define libc_hidden_data_weak(name)
643#endif
644
645#if IS_IN (rtld)
646# define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
647# define rtld_hidden_def(name) hidden_def (name)
648# define rtld_hidden_weak(name) hidden_weak (name)
649# define rtld_hidden_data_def(name) hidden_data_def (name)
650#else
651# define rtld_hidden_proto(name, attrs...)
652# define rtld_hidden_def(name)
653# define rtld_hidden_weak(name)
654# define rtld_hidden_data_def(name)
655#endif
656
657#if IS_IN (libm)
658# define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
659# define libm_hidden_def(name) hidden_def (name)
660# define libm_hidden_weak(name) hidden_weak (name)
661# define libm_hidden_ver(local, name) hidden_ver (local, name)
662#else
663# define libm_hidden_proto(name, attrs...)
664# define libm_hidden_def(name)
665# define libm_hidden_weak(name)
666# define libm_hidden_ver(local, name)
667#endif
668
669#if IS_IN (libmvec)
670# define libmvec_hidden_def(name) hidden_def (name)
671#else
672# define libmvec_hidden_def(name)
673#endif
674
675#if IS_IN (libresolv)
676# define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
677# define libresolv_hidden_def(name) hidden_def (name)
678# define libresolv_hidden_data_def(name) hidden_data_def (name)
679#else
680# define libresolv_hidden_proto(name, attrs...)
681# define libresolv_hidden_def(name)
682# define libresolv_hidden_data_def(name)
683#endif
684
685#if IS_IN (libpthread)
686# define libpthread_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
687# define libpthread_hidden_def(name) hidden_def (name)
688#else
689# define libpthread_hidden_proto(name, attrs...)
690# define libpthread_hidden_def(name)
691#endif
692
693#if IS_IN (librt)
694# define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
695# define librt_hidden_ver(local, name) hidden_ver (local, name)
696#else
697# define librt_hidden_proto(name, attrs...)
698# define librt_hidden_ver(local, name)
699#endif
700
701#if IS_IN (libnsl)
702# define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
703# define libnsl_hidden_nolink_def(name, version) hidden_nolink (name, libnsl, version)
704#else
705# define libnsl_hidden_proto(name, attrs...)
706#endif
707
708#define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
709#define libc_hidden_builtin_def(name) libc_hidden_def (name)
710
711#define libc_hidden_ldbl_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
712#ifdef __ASSEMBLER__
713# define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
714#endif
715
716#if IS_IN (libanl)
717# define libanl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
718#else
719# define libanl_hidden_proto(name, attrs...)
720#endif
721
722/* Get some dirty hacks. */
723#include <symbol-hacks.h>
724
725/* Move compatibility symbols out of the way by placing them all in a
726 special section. */
727#ifndef __ASSEMBLER__
728# define attribute_compat_text_section \
729 __attribute__ ((section (".text.compat")))
730#else
731# define compat_text_section .section ".text.compat", "ax";
732#endif
733
734/* Helper / base macros for indirect function symbols. */
735#define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \
736 classifier inhibit_stack_protector \
737 __typeof (type_name) *name##_ifunc (arg) \
738 { \
739 init (); \
740 __typeof (type_name) *res = expr; \
741 return res; \
742 }
743
744#ifdef HAVE_GCC_IFUNC
745# define __ifunc(type_name, name, expr, arg, init) \
746 extern __typeof (type_name) name __attribute__ \
747 ((ifunc (#name "_ifunc"))); \
748 __ifunc_resolver (type_name, name, expr, arg, init, static)
749
750# define __ifunc_hidden(type_name, name, expr, arg, init) \
751 __ifunc (type_name, name, expr, arg, init)
752#else
753/* Gcc does not support __attribute__ ((ifunc (...))). Use the old behaviour
754 as fallback. But keep in mind that the debug information for the ifunc
755 resolver functions is not correct. It contains the ifunc'ed function as
756 DW_AT_linkage_name. E.g. lldb uses this field and an inferior function
757 call of the ifunc'ed function will fail due to "no matching function for
758 call to ..." because the ifunc'ed function and the resolver function have
759 different signatures. (Gcc support is disabled at least on a ppc64le
760 Ubuntu 14.04 system.) */
761
762# define __ifunc(type_name, name, expr, arg, init) \
763 extern __typeof (type_name) name; \
764 __typeof (type_name) *name##_ifunc (arg) __asm__ (#name); \
765 __ifunc_resolver (type_name, name, expr, arg, init,) \
766 __asm__ (".type " #name ", %gnu_indirect_function");
767
768# define __ifunc_hidden(type_name, name, expr, arg, init) \
769 extern __typeof (type_name) __libc_##name; \
770 __ifunc (type_name, __libc_##name, expr, arg, init) \
771 strong_alias (__libc_##name, name);
772#endif /* !HAVE_GCC_IFUNC */
773
774/* The following macros are used for indirect function symbols in libc.so.
775 First of all, you need to have the function prototyped somewhere,
776 say in foo.h:
777
778 int foo (int __bar);
779
780 If you have an implementation for foo which e.g. uses a special hardware
781 feature which isn't available on all machines where this libc.so will be
782 used but decideable if available at runtime e.g. via hwcaps, you can provide
783 two or multiple implementations of foo:
784
785 int __foo_default (int __bar)
786 {
787 return __bar;
788 }
789
790 int __foo_special (int __bar)
791 {
792 return __bar;
793 }
794
795 If your function foo has no libc_hidden_proto (foo) defined for PLT
796 bypassing, you can use:
797
798 #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
799
800 libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
801
802 This will define a resolver function for foo which returns __foo_special or
803 __foo_default depending on your specified expression. Please note that you
804 have to define a macro function INIT_ARCH before using libc_ifunc macro as
805 it is called by the resolver function before evaluating the specified
806 expression. In this example it is used to prepare the hwcap variable.
807 The resolver function is assigned to an ifunc'ed symbol foo. Calls to foo
808 from inside or outside of libc.so will be indirected by a PLT call.
809
810 If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
811 and calls to foo within libc.so should always go to one specific
812 implementation of foo e.g. __foo_default then you have to add:
813
814 __hidden_ver1 (__foo_default, __GI_foo, __foo_default);
815
816 or a tweaked definition of libc_hidden_def macro after the __foo_default
817 function definition. Calls to foo within libc.so will always go directly to
818 __foo_default. Calls to foo from outside libc.so will be indirected by a
819 PLT call to ifunc'ed symbol foo which you have to define in a separate
820 compile unit:
821
822 #define foo __redirect_foo
823 #include <foo.h>
824 #undef foo
825
826 extern __typeof (__redirect_foo) __foo_default attribute_hidden;
827 extern __typeof (__redirect_foo) __foo_special attribute_hidden;
828
829 libc_ifunc_redirected (__redirect_foo, foo,
830 (hwcap & HWCAP_SPECIAL)
831 ? __foo_special
832 : __foo_default);
833
834 This will define the ifunc'ed symbol foo like above. The redirection of foo
835 in header file is needed to omit an additional defintion of __GI_foo which
836 would end in a linker error while linking libc.so. You have to specify
837 __redirect_foo as first parameter which is used within libc_ifunc_redirected
838 macro in conjunction with typeof to define the ifunc'ed symbol foo.
839
840 If your function foo has a libc_hidden_proto (foo) defined and calls to foo
841 within or from outside libc.so should go via ifunc'ed symbol, then you have
842 to use:
843
844 libc_ifunc_hidden (foo, foo,
845 (hwcap & HWCAP_SPECIAL)
846 ? __foo_special
847 : __foo_default);
848 libc_hidden_def (foo)
849
850 The first parameter foo of libc_ifunc_hidden macro is used in the same way
851 as for libc_ifunc_redirected macro. */
852
853#define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
854
855#define libc_ifunc_redirected(redirected_name, name, expr) \
856 __ifunc (redirected_name, name, expr, void, INIT_ARCH)
857
858#define libc_ifunc_hidden(redirected_name, name, expr) \
859 __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
860
861/* The body of the function is supposed to use __get_cpu_features
862 which will, if necessary, initialize the data first. */
863#define libm_ifunc_init()
864#define libm_ifunc(name, expr) \
865 __ifunc (name, name, expr, void, libm_ifunc_init)
866
867/* Add the compiler optimization to inhibit loop transformation to library
868 calls. This is used to avoid recursive calls in memset and memmove
869 default implementations. */
870#ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
871# define inhibit_loop_to_libcall \
872 __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
873#else
874# define inhibit_loop_to_libcall
875#endif
876
877/* These macros facilitate sharing source files with gnulib.
878
879 They are here instead of sys/cdefs.h because they should not be
880 used in public header files.
881
882 Their definitions should be kept consistent with the definitions in
883 gnulib-common.m4, but it is not necessary to cater to old non-GCC
884 compilers, since they will only be used while building glibc itself.
885 (Note that _GNUC_PREREQ cannot be used in this file.) */
886
887/* Define as a marker that can be attached to declarations that might not
888 be used. This helps to reduce warnings, such as from
889 GCC -Wunused-parameter. */
890#if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
891# define _GL_UNUSED __attribute__ ((__unused__))
892#else
893# define _GL_UNUSED
894#endif
895
896/* gcc supports the "unused" attribute on possibly unused labels, and
897 g++ has since version 4.5. Note to support C++ as well as C,
898 _GL_UNUSED_LABEL should be used with a trailing ; */
899#if !defined __cplusplus || __GNUC__ > 4 \
900 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
901# define _GL_UNUSED_LABEL _GL_UNUSED
902#else
903# define _GL_UNUSED_LABEL
904#endif
905
906/* The __pure__ attribute was added in gcc 2.96. */
907#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
908# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
909#else
910# define _GL_ATTRIBUTE_PURE /* empty */
911#endif
912
913/* The __const__ attribute was added in gcc 2.95. */
914#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
915# define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
916#else
917# define _GL_ATTRIBUTE_CONST /* empty */
918#endif
919
920#endif /* !_ISOMAC */
921#endif /* libc-symbols.h */
922