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) 1995-2021 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/* Same as WEAK_ALIAS, but mark symbol as hidden. */
159# define weak_hidden_alias(name, aliasname) \
160 _weak_hidden_alias (name, aliasname)
161# define _weak_hidden_alias(name, aliasname) \
162 extern __typeof (name) aliasname \
163 __attribute__ ((weak, alias (#name), __visibility__ ("hidden"))) \
164 __attribute_copy__ (name);
165
166/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */
167# define weak_extern(symbol) _weak_extern (weak symbol)
168# define _weak_extern(expr) _Pragma (#expr)
169
170/* In shared builds, the expression call_function_static_weak
171 (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
172 identifier) unconditionally, with the (potentially empty) argument
173 list ARGUMENTS. In static builds, if FUNCTION-SYMBOL has a
174 definition, the function is invoked as before; if FUNCTION-SYMBOL
175 is NULL, no call is performed. */
176# ifdef SHARED
177# define call_function_static_weak(func, ...) func (__VA_ARGS__)
178# else /* !SHARED */
179# define call_function_static_weak(func, ...) \
180 ({ \
181 extern __typeof__ (func) func weak_function; \
182 (func != NULL ? func (__VA_ARGS__) : (void)0); \
183 })
184# endif
185
186#else /* __ASSEMBLER__ */
187
188# ifdef HAVE_ASM_SET_DIRECTIVE
189# define strong_alias(original, alias) \
190 .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
191 .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
192# define strong_data_alias(original, alias) strong_alias(original, alias)
193# else
194# define strong_alias(original, alias) \
195 .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
196 C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
197# define strong_data_alias(original, alias) strong_alias(original, alias)
198# endif
199
200# define weak_alias(original, alias) \
201 .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP \
202 C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
203
204# define weak_extern(symbol) \
205 .weak C_SYMBOL_NAME (symbol)
206
207#endif /* __ASSEMBLER__ */
208
209/* Determine the return address. */
210#define RETURN_ADDRESS(nr) \
211 __builtin_extract_return_addr (__builtin_return_address (nr))
212
213/* When a reference to SYMBOL is encountered, the linker will emit a
214 warning message MSG. */
215/* We want the .gnu.warning.SYMBOL section to be unallocated. */
216#define __make_section_unallocated(section_string) \
217 asm (".section " section_string "\n\t.previous");
218
219/* Tacking on "\n\t#" to the section name makes gcc put it's bogus
220 section attributes on what looks like a comment to the assembler. */
221#ifdef HAVE_SECTION_QUOTES
222# define __sec_comment "\"\n\t#\""
223#else
224# define __sec_comment "\n\t#"
225#endif
226#define link_warning(symbol, msg) \
227 __make_section_unallocated (".gnu.warning." #symbol) \
228 static const char __evoke_link_warning_##symbol[] \
229 __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
230 = msg;
231
232/* A canned warning for sysdeps/stub functions. */
233#define stub_warning(name) \
234 __make_section_unallocated (".gnu.glibc-stub." #name) \
235 link_warning (name, #name " is not implemented and will always fail")
236
237/* Warning for linking functions calling dlopen into static binaries. */
238#ifdef SHARED
239#define static_link_warning(name)
240#else
241#define static_link_warning(name) static_link_warning1(name)
242#define static_link_warning1(name) \
243 link_warning(name, "Using '" #name "' in statically linked applications \
244requires at runtime the shared libraries from the glibc version used \
245for linking")
246#endif
247
248/* Resource Freeing Hooks:
249
250 Normally a process exits and the OS cleans up any allocated
251 memory. However, when tooling like mtrace or valgrind is monitoring
252 the process we need to free all resources that are part of the
253 process in order to provide the consistency required to track
254 memory leaks.
255
256 A single public API exists and is __libc_freeres(), and this is used
257 by applications like valgrind to freee resouces.
258
259 There are 3 cases:
260
261 (a) __libc_freeres
262
263 In this case all you need to do is define the freeing routine:
264
265 foo.c:
266 libfoo_freeres_fn (foo_freeres)
267 {
268 complex_free (mem);
269 }
270
271 This ensures the function is called at the right point to free
272 resources.
273
274 (b) __libc_freeres_ptr
275
276 The framework for (a) iterates over the list of pointers-to-free
277 in (b) and frees them.
278
279 foo.c:
280 libc_freeres_ptr (static char *foo_buffer);
281
282 Freeing these resources alaways happens last and is equivalent
283 to registering a function that does 'free (foo_buffer)'.
284
285 (c) Explicit lists of free routines to call or objects to free.
286
287 It is the intended goal to remove (a) and (b) which have some
288 non-determinism based on link order, and instead use explicit
289 lists of functions and frees to resolve cleanup ordering issues
290 and make it easy to debug and maintain.
291
292 As of today the following subsystems use (c):
293
294 Per-thread cleanup:
295 * malloc/thread-freeres.c
296
297 libdl cleanup:
298 * dlfcn/dlfreeres.c
299
300 libpthread cleanup:
301 * nptl/nptlfreeres.c
302
303 So if you need any shutdown routines to run you should add them
304 directly to the appropriate subsystem's shutdown list. */
305
306/* Resource pointers to free in libc.so. */
307#define libc_freeres_ptr(decl) \
308 __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
309 decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
310
311/* Resource freeing functions from libc.so go in this section. */
312#define __libc_freeres_fn_section \
313 __attribute__ ((__used__, section ("__libc_freeres_fn")))
314
315/* Resource freeing functions for libc.so. */
316#define libc_freeres_fn(name) \
317 static void name (void) __attribute_used__ __libc_freeres_fn_section; \
318 text_set_element (__libc_subfreeres, name); \
319 static void name (void)
320
321/* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
322 alias to ORIGINAL, when the assembler supports such declarations
323 (such as in ELF).
324 This is only necessary when defining something in assembly, or playing
325 funny alias games where the size should be other than what the compiler
326 thinks it is. */
327#define declare_symbol_alias(symbol, original, type, size) \
328 declare_symbol_alias_1 (symbol, original, type, size)
329#ifdef __ASSEMBLER__
330# define declare_symbol_alias_1(symbol, original, type, size) \
331 strong_alias (original, symbol); \
332 .type C_SYMBOL_NAME (symbol), %##type; \
333 .size C_SYMBOL_NAME (symbol), size
334#else /* Not __ASSEMBLER__. */
335# define declare_symbol_alias_1(symbol, original, type, size) \
336 asm (".globl " __SYMBOL_PREFIX #symbol \
337 "\n\t" declare_symbol_alias_1_alias (symbol, original) \
338 "\n\t.type " __SYMBOL_PREFIX #symbol ", " \
339 "%" #type \
340 "\n\t.size " __SYMBOL_PREFIX #symbol ", " #size);
341# ifdef HAVE_ASM_SET_DIRECTIVE
342# define declare_symbol_alias_1_alias(symbol, original) \
343 ".set " __SYMBOL_PREFIX #symbol ", " __SYMBOL_PREFIX #original
344# else
345# define declare_symbol_alias_1_alias(symbol, original) \
346 __SYMBOL_PREFIX #symbol " = " __SYMBOL_PREFIX #original
347# endif /* HAVE_ASM_SET_DIRECTIVE */
348#endif /* __ASSEMBLER__ */
349
350
351/*
352
353*/
354
355#ifdef HAVE_GNU_RETAIN
356# define attribute_used_retain __attribute__ ((__used__, __retain__))
357#else
358# define attribute_used_retain __attribute__ ((__used__))
359#endif
360
361/* Symbol set support macros. */
362
363/* Make SYMBOL, which is in the text segment, an element of SET. */
364#define text_set_element(set, symbol) _elf_set_element(set, symbol)
365/* Make SYMBOL, which is in the data segment, an element of SET. */
366#define data_set_element(set, symbol) _elf_set_element(set, symbol)
367/* Make SYMBOL, which is in the bss segment, an element of SET. */
368#define bss_set_element(set, symbol) _elf_set_element(set, symbol)
369
370/* These are all done the same way in ELF.
371 There is a new section created for each set. */
372#ifdef SHARED
373/* When building a shared library, make the set section writable,
374 because it will need to be relocated at run time anyway. */
375# define _elf_set_element(set, symbol) \
376 static const void *__elf_set_##set##_element_##symbol##__ \
377 attribute_used_retain __attribute__ ((section (#set))) = &(symbol)
378#else
379# define _elf_set_element(set, symbol) \
380 static const void *const __elf_set_##set##_element_##symbol##__ \
381 attribute_used_retain __attribute__ ((section (#set))) = &(symbol)
382#endif
383
384/* Define SET as a symbol set. This may be required (it is in a.out) to
385 be able to use the set's contents. */
386#define symbol_set_define(set) symbol_set_declare(set)
387
388/* Declare SET for use in this module, if defined in another module.
389 In a shared library, this is always local to that shared object.
390 For static linking, the set might be wholly absent and so we use
391 weak references. */
392#define symbol_set_declare(set) \
393 extern char const __start_##set[] __symbol_set_attribute; \
394 extern char const __stop_##set[] __symbol_set_attribute;
395#ifdef SHARED
396# define __symbol_set_attribute attribute_hidden
397#else
398# define __symbol_set_attribute __attribute__ ((weak))
399#endif
400
401/* Return a pointer (void *const *) to the first element of SET. */
402#define symbol_set_first_element(set) ((void *const *) (&__start_##set))
403
404/* Return true iff PTR (a void *const *) has been incremented
405 past the last element in SET. */
406#define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
407
408#ifdef SHARED
409# define symbol_version(real, name, version) \
410 symbol_version_reference(real, name, version)
411# define default_symbol_version(real, name, version) \
412 _default_symbol_version(real, name, version)
413/* See <libc-symver.h>. */
414# ifdef __ASSEMBLER__
415# define _default_symbol_version(real, name, version) \
416 _set_symbol_version (real, name@@version)
417# else
418# define _default_symbol_version(real, name, version) \
419 _set_symbol_version (real, #name "@@" #version)
420# endif
421
422/* Evalutes to a string literal for VERSION in LIB. */
423# define symbol_version_string(lib, version) \
424 _symbol_version_stringify_1 (VERSION_##lib##_##version)
425# define _symbol_version_stringify_1(arg) _symbol_version_stringify_2 (arg)
426# define _symbol_version_stringify_2(arg) #arg
427
428#else /* !SHARED */
429# define symbol_version(real, name, version)
430# define default_symbol_version(real, name, version) \
431 strong_alias(real, name)
432#endif
433
434#if defined SHARED || defined LIBC_NONSHARED \
435 || (BUILD_PIE_DEFAULT && IS_IN (libc))
436# define attribute_hidden __attribute__ ((visibility ("hidden")))
437#else
438# define attribute_hidden
439#endif
440
441#define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
442
443#define attribute_relro __attribute__ ((section (".data.rel.ro")))
444
445
446/* Used to disable stack protection in sensitive places, like ifunc
447 resolvers and early static TLS init. */
448#ifdef HAVE_CC_NO_STACK_PROTECTOR
449# define inhibit_stack_protector \
450 __attribute__ ((__optimize__ ("-fno-stack-protector")))
451#else
452# define inhibit_stack_protector
453#endif
454
455/* The following macros are used for PLT bypassing within libc.so
456 (and if needed other libraries similarly).
457 First of all, you need to have the function prototyped somewhere,
458 say in foo/foo.h:
459
460 int foo (int __bar);
461
462 If calls to foo within libc.so should always go to foo defined in libc.so,
463 then in include/foo.h you add:
464
465 libc_hidden_proto (foo)
466
467 line and after the foo function definition:
468
469 int foo (int __bar)
470 {
471 return __bar;
472 }
473 libc_hidden_def (foo)
474
475 or
476
477 int foo (int __bar)
478 {
479 return __bar;
480 }
481 libc_hidden_weak (foo)
482
483 Similarly for global data. If references to foo within libc.so should
484 always go to foo defined in libc.so, then in include/foo.h you add:
485
486 libc_hidden_proto (foo)
487
488 line and after foo's definition:
489
490 int foo = INITIAL_FOO_VALUE;
491 libc_hidden_data_def (foo)
492
493 or
494
495 int foo = INITIAL_FOO_VALUE;
496 libc_hidden_data_weak (foo)
497
498 If foo is normally just an alias (strong or weak) to some other function,
499 you should use the normal strong_alias first, then add libc_hidden_def
500 or libc_hidden_weak:
501
502 int baz (int __bar)
503 {
504 return __bar;
505 }
506 strong_alias (baz, foo)
507 libc_hidden_weak (foo)
508
509 If the function should be internal to multiple objects, say ld.so and
510 libc.so, the best way is to use:
511
512 #if IS_IN (libc) || IS_IN (rtld)
513 hidden_proto (foo)
514 #endif
515
516 in include/foo.h and the normal macros at all function definitions
517 depending on what DSO they belong to.
518
519 If versioned_symbol macro is used to define foo,
520 libc_hidden_ver macro should be used, as in:
521
522 int __real_foo (int __bar)
523 {
524 return __bar;
525 }
526 versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
527 libc_hidden_ver (__real_foo, foo) */
528
529#if defined SHARED && !defined NO_HIDDEN
530# ifndef __ASSEMBLER__
531# define __hidden_proto_hiddenattr(attrs...) \
532 __attribute__ ((visibility ("hidden"), ##attrs))
533# define hidden_proto(name, attrs...) \
534 __hidden_proto (name, , __GI_##name, ##attrs)
535# define hidden_tls_proto(name, attrs...) \
536 __hidden_proto (name, __thread, __GI_##name, ##attrs)
537# define __hidden_proto(name, thread, internal, attrs...) \
538 extern thread __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
539 __hidden_proto_hiddenattr (attrs);
540# define __hidden_asmname(name) \
541 __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
542# define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
543# define __hidden_asmname2(prefix, name) #prefix name
544# define __hidden_ver1(local, internal, name) \
545 __hidden_ver2 (, local, internal, name)
546# define __hidden_ver2(thread, local, internal, name) \
547 extern thread __typeof (name) __EI_##name \
548 __asm__(__hidden_asmname (#internal)); \
549 extern thread __typeof (name) __EI_##name \
550 __attribute__((alias (__hidden_asmname (#local)))) \
551 __attribute_copy__ (name)
552# define hidden_ver(local, name) __hidden_ver1(local, __GI_##name, name);
553# define hidden_data_ver(local, name) hidden_ver(local, name)
554# define hidden_def(name) __hidden_ver1(__GI_##name, name, name);
555# define hidden_data_def(name) hidden_def(name)
556# define hidden_tls_def(name) \
557 __hidden_ver2 (__thread, __GI_##name, name, name);
558# define hidden_weak(name) \
559 __hidden_ver1(__GI_##name, name, name) __attribute__((weak));
560# define hidden_data_weak(name) hidden_weak(name)
561# define hidden_nolink(name, lib, version) \
562 __hidden_nolink1 (__GI_##name, __EI_##name, name, VERSION_##lib##_##version)
563# define __hidden_nolink1(local, internal, name, version) \
564 __hidden_nolink2 (local, internal, name, version)
565# define __hidden_nolink2(local, internal, name, version) \
566 extern __typeof (name) internal __attribute__ ((alias (#local))) \
567 __attribute_copy__ (name); \
568 __hidden_nolink3 (local, internal, #name "@" #version)
569# define __hidden_nolink3(local, internal, vername) \
570 __asm__ (".symver " #internal ", " vername);
571# else
572/* For assembly, we need to do the opposite of what we do in C:
573 in assembly gcc __REDIRECT stuff is not in place, so functions
574 are defined by its normal name and we need to create the
575 __GI_* alias to it, in C __REDIRECT causes the function definition
576 to use __GI_* name and we need to add alias to the real name.
577 There is no reason to use hidden_weak over hidden_def in assembly,
578 but we provide it for consistency with the C usage.
579 hidden_proto doesn't make sense for assembly but the equivalent
580 is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET. */
581# define hidden_def(name) strong_alias (name, __GI_##name)
582# define hidden_weak(name) hidden_def (name)
583# define hidden_ver(local, name) strong_alias (local, __GI_##name)
584# define hidden_data_def(name) strong_data_alias (name, __GI_##name)
585# define hidden_tls_def(name) hidden_data_def (name)
586# define hidden_data_weak(name) hidden_data_def (name)
587# define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
588# define HIDDEN_JUMPTARGET(name) __GI_##name
589# endif
590#else
591# ifndef __ASSEMBLER__
592# if !defined SHARED && IS_IN (libc) && !defined LIBC_NONSHARED \
593 && (!defined PIC || !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE) \
594 && !defined NO_HIDDEN
595# define __hidden_proto_hiddenattr(attrs...) \
596 __attribute__ ((visibility ("hidden"), ##attrs))
597# define hidden_proto(name, attrs...) \
598 __hidden_proto (name, , name, ##attrs)
599# define hidden_tls_proto(name, attrs...) \
600 __hidden_proto (name, __thread, name, ##attrs)
601# define __hidden_proto(name, thread, internal, attrs...) \
602 extern thread __typeof (name) name __hidden_proto_hiddenattr (attrs);
603# else
604# define hidden_proto(name, attrs...)
605# define hidden_tls_proto(name, attrs...)
606# endif
607# else
608# define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
609# endif /* Not __ASSEMBLER__ */
610# define hidden_weak(name)
611# define hidden_def(name)
612# define hidden_ver(local, name)
613# define hidden_data_weak(name)
614# define hidden_data_def(name)
615# define hidden_tls_def(name)
616# define hidden_data_ver(local, name)
617# define hidden_nolink(name, lib, version)
618#endif
619
620#if IS_IN (libc)
621# define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
622# define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
623# define libc_hidden_def(name) hidden_def (name)
624# define libc_hidden_weak(name) hidden_weak (name)
625# define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
626# define libc_hidden_ver(local, name) hidden_ver (local, name)
627# define libc_hidden_data_def(name) hidden_data_def (name)
628# define libc_hidden_tls_def(name) hidden_tls_def (name)
629# define libc_hidden_data_weak(name) hidden_data_weak (name)
630# define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
631#else
632# define libc_hidden_proto(name, attrs...)
633# define libc_hidden_tls_proto(name, attrs...)
634# define libc_hidden_def(name)
635# define libc_hidden_weak(name)
636# define libc_hidden_ver(local, name)
637# define libc_hidden_data_def(name)
638# define libc_hidden_tls_def(name)
639# define libc_hidden_data_weak(name)
640# define libc_hidden_data_ver(local, name)
641#endif
642
643#if IS_IN (rtld)
644# define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
645# define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
646# define rtld_hidden_def(name) hidden_def (name)
647# define rtld_hidden_weak(name) hidden_weak (name)
648# define rtld_hidden_ver(local, name) hidden_ver (local, name)
649# define rtld_hidden_data_def(name) hidden_data_def (name)
650# define rtld_hidden_tls_def(name) hidden_tls_def (name)
651# define rtld_hidden_data_weak(name) hidden_data_weak (name)
652# define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
653#else
654# define rtld_hidden_proto(name, attrs...)
655# define rtld_hidden_tls_proto(name, attrs...)
656# define rtld_hidden_def(name)
657# define rtld_hidden_weak(name)
658# define rtld_hidden_ver(local, name)
659# define rtld_hidden_data_def(name)
660# define rtld_hidden_tls_def(name)
661# define rtld_hidden_data_weak(name)
662# define rtld_hidden_data_ver(local, name)
663#endif
664
665#if IS_IN (libm)
666# define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
667# define libm_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
668# define libm_hidden_def(name) hidden_def (name)
669# define libm_hidden_weak(name) hidden_weak (name)
670# define libm_hidden_ver(local, name) hidden_ver (local, name)
671# define libm_hidden_data_def(name) hidden_data_def (name)
672# define libm_hidden_tls_def(name) hidden_tls_def (name)
673# define libm_hidden_data_weak(name) hidden_data_weak (name)
674# define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
675#else
676# define libm_hidden_proto(name, attrs...)
677# define libm_hidden_tls_proto(name, attrs...)
678# define libm_hidden_def(name)
679# define libm_hidden_weak(name)
680# define libm_hidden_ver(local, name)
681# define libm_hidden_data_def(name)
682# define libm_hidden_tls_def(name)
683# define libm_hidden_data_weak(name)
684# define libm_hidden_data_ver(local, name)
685#endif
686
687#if IS_IN (libmvec)
688# define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
689# define libmvec_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
690# define libmvec_hidden_def(name) hidden_def (name)
691# define libmvec_hidden_weak(name) hidden_weak (name)
692# define libmvec_hidden_ver(local, name) hidden_ver (local, name)
693# define libmvec_hidden_data_def(name) hidden_data_def (name)
694# define libmvec_hidden_tls_def(name) hidden_tls_def (name)
695# define libmvec_hidden_data_weak(name) hidden_data_weak (name)
696# define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
697#else
698# define libmvec_hidden_proto(name, attrs...)
699# define libmvec_hidden_tls_proto(name, attrs...)
700# define libmvec_hidden_def(name)
701# define libmvec_hidden_weak(name)
702# define libmvec_hidden_ver(local, name)
703# define libmvec_hidden_data_def(name)
704# define libmvec_hidden_tls_def(name)
705# define libmvec_hidden_data_weak(name)
706# define libmvec_hidden_data_ver(local, name)
707#endif
708
709#if IS_IN (libresolv)
710# define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
711# define libresolv_hidden_tls_proto(name, attrs...) \
712 hidden_tls_proto (name, ##attrs)
713# define libresolv_hidden_def(name) hidden_def (name)
714# define libresolv_hidden_weak(name) hidden_weak (name)
715# define libresolv_hidden_ver(local, name) hidden_ver (local, name)
716# define libresolv_hidden_data_def(name) hidden_data_def (name)
717# define libresolv_hidden_tls_def(name) hidden_tls_def (name)
718# define libresolv_hidden_data_weak(name) hidden_data_weak (name)
719# define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
720#else
721# define libresolv_hidden_proto(name, attrs...)
722# define libresolv_hidden_tls_proto(name, attrs...)
723# define libresolv_hidden_def(name)
724# define libresolv_hidden_weak(name)
725# define libresolv_hidden_ver(local, name)
726# define libresolv_hidden_data_def(name)
727# define libresolv_hidden_tls_def(name)
728# define libresolv_hidden_data_weak(name)
729# define libresolv_hidden_data_ver(local, name)
730#endif
731
732#if IS_IN (libpthread)
733# define libpthread_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
734# define libpthread_hidden_tls_proto(name, attrs...) \
735 hidden_tls_proto (name, ##attrs)
736# define libpthread_hidden_def(name) hidden_def (name)
737# define libpthread_hidden_weak(name) hidden_weak (name)
738# define libpthread_hidden_ver(local, name) hidden_ver (local, name)
739# define libpthread_hidden_data_def(name) hidden_data_def (name)
740# define libpthread_hidden_tls_def(name) hidden_tls_def (name)
741# define libpthread_hidden_data_weak(name) hidden_data_weak (name)
742# define libpthread_hidden_data_ver(local, name) hidden_data_ver (local, name)
743#else
744# define libpthread_hidden_proto(name, attrs...)
745# define libpthread_hidden_tls_proto(name, attrs...)
746# define libpthread_hidden_def(name)
747# define libpthread_hidden_weak(name)
748# define libpthread_hidden_ver(local, name)
749# define libpthread_hidden_data_def(name)
750# define libpthread_hidden_tls_def(name)
751# define libpthread_hidden_data_weak(name)
752# define libpthread_hidden_data_ver(local, name)
753#endif
754
755#if IS_IN (librt)
756# define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
757# define librt_hidden_tls_proto(name, attrs...) \
758 hidden_tls_proto (name, ##attrs)
759# define librt_hidden_def(name) hidden_def (name)
760# define librt_hidden_weak(name) hidden_weak (name)
761# define librt_hidden_ver(local, name) hidden_ver (local, name)
762# define librt_hidden_data_def(name) hidden_data_def (name)
763# define librt_hidden_tls_def(name) hidden_tls_def (name)
764# define librt_hidden_data_weak(name) hidden_data_weak (name)
765# define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
766#else
767# define librt_hidden_proto(name, attrs...)
768# define librt_hidden_tls_proto(name, attrs...)
769# define librt_hidden_def(name)
770# define librt_hidden_weak(name)
771# define librt_hidden_ver(local, name)
772# define librt_hidden_data_def(name)
773# define librt_hidden_tls_def(name)
774# define librt_hidden_data_weak(name)
775# define librt_hidden_data_ver(local, name)
776#endif
777
778#if IS_IN (libdl)
779# define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
780# define libdl_hidden_tls_proto(name, attrs...) \
781 hidden_tls_proto (name, ##attrs)
782# define libdl_hidden_def(name) hidden_def (name)
783# define libdl_hidden_weak(name) hidden_weak (name)
784# define libdl_hidden_ver(local, name) hidden_ver (local, name)
785# define libdl_hidden_data_def(name) hidden_data_def (name)
786# define libdl_hidden_tls_def(name) hidden_tls_def (name)
787# define libdl_hidden_data_weak(name) hidden_data_weak (name)
788# define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
789#else
790# define libdl_hidden_proto(name, attrs...)
791# define libdl_hidden_tls_proto(name, attrs...)
792# define libdl_hidden_def(name)
793# define libdl_hidden_weak(name)
794# define libdl_hidden_ver(local, name)
795# define libdl_hidden_data_def(name)
796# define libdl_hidden_tls_def(name)
797# define libdl_hidden_data_weak(name)
798# define libdl_hidden_data_ver(local, name)
799#endif
800
801#if IS_IN (libnsl)
802# define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
803# define libnsl_hidden_tls_proto(name, attrs...) \
804 hidden_tls_proto (name, ##attrs)
805# define libnsl_hidden_nolink_def(name, version) hidden_nolink (name, libnsl, version)
806# define libnsl_hidden_weak(name) hidden_weak (name)
807# define libnsl_hidden_ver(local, name) hidden_ver (local, name)
808# define libnsl_hidden_data_def(name) hidden_data_def (name)
809# define libnsl_hidden_tls_def(name) hidden_tls_def (name)
810# define libnsl_hidden_data_weak(name) hidden_data_weak (name)
811# define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
812#else
813# define libnsl_hidden_proto(name, attrs...)
814# define libnsl_hidden_tls_proto(name, attrs...)
815# define libnsl_hidden_weak(name)
816# define libnsl_hidden_ver(local, name)
817# define libnsl_hidden_data_def(name)
818# define libnsl_hidden_tls_def(name)
819# define libnsl_hidden_data_weak(name)
820# define libnsl_hidden_data_ver(local, name)
821#endif
822
823#define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
824#define libc_hidden_builtin_def(name) libc_hidden_def (name)
825#define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
826#define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
827
828#define libc_hidden_ldbl_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
829#ifdef __ASSEMBLER__
830# define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
831#endif
832
833#if IS_IN (libutil)
834# define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
835# define libutil_hidden_tls_proto(name, attrs...) \
836 hidden_tls_proto (name, ##attrs)
837# define libutil_hidden_def(name) hidden_def (name)
838# define libutil_hidden_weak(name) hidden_weak (name)
839# define libutil_hidden_ver(local, name) hidden_ver (local, name)
840# define libutil_hidden_data_def(name) hidden_data_def (name)
841# define libutil_hidden_tls_def(name) hidden_tls_def (name)
842# define libutil_hidden_data_weak(name) hidden_data_weak (name)
843# define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
844#else
845# define libutil_hidden_proto(name, attrs...)
846# define libutil_hidden_tls_proto(name, attrs...)
847# define libutil_hidden_def(name)
848# define libutil_hidden_weak(name)
849# define libutil_hidden_ver(local, name)
850# define libutil_hidden_data_def(name)
851# define libutil_hidden_tls_def(name)
852# define libutil_hidden_data_weak(name)
853# define libutil_hidden_data_ver(local, name)
854#endif
855
856#if IS_IN (libanl)
857# define libanl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
858# define libanl_hidden_def(name) hidden_def (name)
859#else
860# define libanl_hidden_proto(name, attrs...)
861# define libanl_hidden_def(name)
862#endif
863
864/* Get some dirty hacks. */
865#include <symbol-hacks.h>
866
867/* Move compatibility symbols out of the way by placing them all in a
868 special section. */
869#ifndef __ASSEMBLER__
870# define attribute_compat_text_section \
871 __attribute__ ((section (".text.compat")))
872# define attribute_compat_data_section \
873 __attribute__ ((section (".data.compat")))
874#else
875# define compat_text_section .section ".text.compat", "ax";
876# define compat_data_section .section ".data.compat", "aw";
877#endif
878
879/* Helper / base macros for indirect function symbols. */
880#define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \
881 classifier inhibit_stack_protector \
882 __typeof (type_name) *name##_ifunc (arg) \
883 { \
884 init (); \
885 __typeof (type_name) *res = expr; \
886 return res; \
887 }
888
889#ifdef HAVE_GCC_IFUNC
890# define __ifunc(type_name, name, expr, arg, init) \
891 extern __typeof (type_name) name __attribute__ \
892 ((ifunc (#name "_ifunc"))); \
893 __ifunc_resolver (type_name, name, expr, arg, init, static)
894
895# define __ifunc_hidden(type_name, name, expr, arg, init) \
896 __ifunc (type_name, name, expr, arg, init)
897#else
898/* Gcc does not support __attribute__ ((ifunc (...))). Use the old behaviour
899 as fallback. But keep in mind that the debug information for the ifunc
900 resolver functions is not correct. It contains the ifunc'ed function as
901 DW_AT_linkage_name. E.g. lldb uses this field and an inferior function
902 call of the ifunc'ed function will fail due to "no matching function for
903 call to ..." because the ifunc'ed function and the resolver function have
904 different signatures. (Gcc support is disabled at least on a ppc64le
905 Ubuntu 14.04 system.) */
906
907# define __ifunc(type_name, name, expr, arg, init) \
908 extern __typeof (type_name) name; \
909 __typeof (type_name) *name##_ifunc (arg) __asm__ (#name); \
910 __ifunc_resolver (type_name, name, expr, arg, init,) \
911 __asm__ (".type " #name ", %gnu_indirect_function");
912
913# define __ifunc_hidden(type_name, name, expr, arg, init) \
914 extern __typeof (type_name) __libc_##name; \
915 __ifunc (type_name, __libc_##name, expr, arg, init) \
916 strong_alias (__libc_##name, name);
917#endif /* !HAVE_GCC_IFUNC */
918
919/* The following macros are used for indirect function symbols in libc.so.
920 First of all, you need to have the function prototyped somewhere,
921 say in foo.h:
922
923 int foo (int __bar);
924
925 If you have an implementation for foo which e.g. uses a special hardware
926 feature which isn't available on all machines where this libc.so will be
927 used but decideable if available at runtime e.g. via hwcaps, you can provide
928 two or multiple implementations of foo:
929
930 int __foo_default (int __bar)
931 {
932 return __bar;
933 }
934
935 int __foo_special (int __bar)
936 {
937 return __bar;
938 }
939
940 If your function foo has no libc_hidden_proto (foo) defined for PLT
941 bypassing, you can use:
942
943 #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
944
945 libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
946
947 This will define a resolver function for foo which returns __foo_special or
948 __foo_default depending on your specified expression. Please note that you
949 have to define a macro function INIT_ARCH before using libc_ifunc macro as
950 it is called by the resolver function before evaluating the specified
951 expression. In this example it is used to prepare the hwcap variable.
952 The resolver function is assigned to an ifunc'ed symbol foo. Calls to foo
953 from inside or outside of libc.so will be indirected by a PLT call.
954
955 If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
956 and calls to foo within libc.so should always go to one specific
957 implementation of foo e.g. __foo_default then you have to add:
958
959 __hidden_ver1 (__foo_default, __GI_foo, __foo_default);
960
961 or a tweaked definition of libc_hidden_def macro after the __foo_default
962 function definition. Calls to foo within libc.so will always go directly to
963 __foo_default. Calls to foo from outside libc.so will be indirected by a
964 PLT call to ifunc'ed symbol foo which you have to define in a separate
965 compile unit:
966
967 #define foo __redirect_foo
968 #include <foo.h>
969 #undef foo
970
971 extern __typeof (__redirect_foo) __foo_default attribute_hidden;
972 extern __typeof (__redirect_foo) __foo_special attribute_hidden;
973
974 libc_ifunc_redirected (__redirect_foo, foo,
975 (hwcap & HWCAP_SPECIAL)
976 ? __foo_special
977 : __foo_default);
978
979 This will define the ifunc'ed symbol foo like above. The redirection of foo
980 in header file is needed to omit an additional defintion of __GI_foo which
981 would end in a linker error while linking libc.so. You have to specify
982 __redirect_foo as first parameter which is used within libc_ifunc_redirected
983 macro in conjunction with typeof to define the ifunc'ed symbol foo.
984
985 If your function foo has a libc_hidden_proto (foo) defined and calls to foo
986 within or from outside libc.so should go via ifunc'ed symbol, then you have
987 to use:
988
989 libc_ifunc_hidden (foo, foo,
990 (hwcap & HWCAP_SPECIAL)
991 ? __foo_special
992 : __foo_default);
993 libc_hidden_def (foo)
994
995 The first parameter foo of libc_ifunc_hidden macro is used in the same way
996 as for libc_ifunc_redirected macro. */
997
998#define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
999
1000#define libc_ifunc_redirected(redirected_name, name, expr) \
1001 __ifunc (redirected_name, name, expr, void, INIT_ARCH)
1002
1003#define libc_ifunc_hidden(redirected_name, name, expr) \
1004 __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
1005
1006/* The body of the function is supposed to use __get_cpu_features
1007 which will, if necessary, initialize the data first. */
1008#define libm_ifunc_init()
1009#define libm_ifunc(name, expr) \
1010 __ifunc (name, name, expr, void, libm_ifunc_init)
1011
1012/* Add the compiler optimization to inhibit loop transformation to library
1013 calls. This is used to avoid recursive calls in memset and memmove
1014 default implementations. */
1015#ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
1016# define inhibit_loop_to_libcall \
1017 __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
1018#else
1019# define inhibit_loop_to_libcall
1020#endif
1021
1022/* These macros facilitate sharing source files with gnulib.
1023
1024 They are here instead of sys/cdefs.h because they should not be
1025 used in public header files.
1026
1027 Their definitions should be kept consistent with the definitions in
1028 gnulib-common.m4, but it is not necessary to cater to old non-GCC
1029 compilers, since they will only be used while building glibc itself.
1030 (Note that _GNUC_PREREQ cannot be used in this file.) */
1031
1032/* Define as a marker that can be attached to declarations that might not
1033 be used. This helps to reduce warnings, such as from
1034 GCC -Wunused-parameter. */
1035#if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
1036# define _GL_UNUSED __attribute__ ((__unused__))
1037#else
1038# define _GL_UNUSED
1039#endif
1040
1041/* gcc supports the "unused" attribute on possibly unused labels, and
1042 g++ has since version 4.5. Note to support C++ as well as C,
1043 _GL_UNUSED_LABEL should be used with a trailing ; */
1044#if !defined __cplusplus || __GNUC__ > 4 \
1045 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
1046# define _GL_UNUSED_LABEL _GL_UNUSED
1047#else
1048# define _GL_UNUSED_LABEL
1049#endif
1050
1051/* The __pure__ attribute was added in gcc 2.96. */
1052#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
1053# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
1054#else
1055# define _GL_ATTRIBUTE_PURE /* empty */
1056#endif
1057
1058/* The __const__ attribute was added in gcc 2.95. */
1059#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
1060# define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
1061#else
1062# define _GL_ATTRIBUTE_CONST /* empty */
1063#endif
1064
1065#endif /* !_ISOMAC */
1066#endif /* libc-symbols.h */
1067