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/* 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 __attribute_copy__
129/* Provide an empty definition when cdefs.h is not included. */
130# define __attribute_copy__(arg)
131#endif
132
133#ifndef __ASSEMBLER__
134/* GCC understands weak symbols and aliases; use its interface where
135 possible, instead of embedded assembly language. */
136
137/* Define ALIASNAME as a strong alias for NAME. */
138# define strong_alias(name, aliasname) _strong_alias(name, aliasname)
139# define _strong_alias(name, aliasname) \
140 extern __typeof (name) aliasname __attribute__ ((alias (#name))) \
141 __attribute_copy__ (name);
142
143/* This comes between the return type and function name in
144 a function definition to make that definition weak. */
145# define weak_function __attribute__ ((weak))
146# define weak_const_function __attribute__ ((weak, __const__))
147
148/* Define ALIASNAME as a weak alias for NAME.
149 If weak aliases are not available, this defines a strong alias. */
150# define weak_alias(name, aliasname) _weak_alias (name, aliasname)
151# define _weak_alias(name, aliasname) \
152 extern __typeof (name) aliasname __attribute__ ((weak, alias (#name))) \
153 __attribute_copy__ (name);
154
155/* Same as WEAK_ALIAS, but mark symbol as hidden. */
156# define weak_hidden_alias(name, aliasname) \
157 _weak_hidden_alias (name, aliasname)
158# define _weak_hidden_alias(name, aliasname) \
159 extern __typeof (name) aliasname \
160 __attribute__ ((weak, alias (#name), __visibility__ ("hidden"))) \
161 __attribute_copy__ (name);
162
163/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */
164# define weak_extern(symbol) _weak_extern (weak symbol)
165# define _weak_extern(expr) _Pragma (#expr)
166
167/* In shared builds, the expression call_function_static_weak
168 (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
169 identifier) unconditionally, with the (potentially empty) argument
170 list ARGUMENTS. In static builds, if FUNCTION-SYMBOL has a
171 definition, the function is invoked as before; if FUNCTION-SYMBOL
172 is NULL, no call is performed. */
173# ifdef SHARED
174# define call_function_static_weak(func, ...) func (__VA_ARGS__)
175# else /* !SHARED */
176# define call_function_static_weak(func, ...) \
177 ({ \
178 extern __typeof__ (func) func weak_function; \
179 (func != NULL ? func (__VA_ARGS__) : (void)0); \
180 })
181# endif
182
183#else /* __ASSEMBLER__ */
184
185# ifdef HAVE_ASM_SET_DIRECTIVE
186# define strong_alias(original, alias) \
187 .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
188 .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
189# define strong_data_alias(original, alias) strong_alias(original, alias)
190# else
191# define strong_alias(original, alias) \
192 .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
193 C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
194# define strong_data_alias(original, alias) strong_alias(original, alias)
195# endif
196
197# define weak_alias(original, alias) \
198 .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP \
199 C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
200
201# define weak_extern(symbol) \
202 .weak C_SYMBOL_NAME (symbol)
203
204#endif /* __ASSEMBLER__ */
205
206/* Determine the return address. */
207#define RETURN_ADDRESS(nr) \
208 __builtin_extract_return_addr (__builtin_return_address (nr))
209
210/* When a reference to SYMBOL is encountered, the linker will emit a
211 warning message MSG. */
212/* We want the .gnu.warning.SYMBOL section to be unallocated. */
213#define __make_section_unallocated(section_string) \
214 asm (".section " section_string "\n\t.previous");
215
216/* Tacking on "\n\t#" to the section name makes gcc put it's bogus
217 section attributes on what looks like a comment to the assembler. */
218#ifdef HAVE_SECTION_QUOTES
219# define __sec_comment "\"\n\t#\""
220#else
221# define __sec_comment "\n\t#"
222#endif
223#define link_warning(symbol, msg) \
224 __make_section_unallocated (".gnu.warning." #symbol) \
225 static const char __evoke_link_warning_##symbol[] \
226 __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
227 = msg;
228
229/* A canned warning for sysdeps/stub functions. */
230#define stub_warning(name) \
231 __make_section_unallocated (".gnu.glibc-stub." #name) \
232 link_warning (name, #name " is not implemented and will always fail")
233
234/* Warning for linking functions calling dlopen into static binaries. */
235#ifdef SHARED
236#define static_link_warning(name)
237#else
238#define static_link_warning(name) static_link_warning1(name)
239#define static_link_warning1(name) \
240 link_warning(name, "Using '" #name "' in statically linked applications \
241requires at runtime the shared libraries from the glibc version used \
242for linking")
243#endif
244
245/* Resource Freeing Hooks:
246
247 Normally a process exits and the OS cleans up any allocated
248 memory. However, when tooling like mtrace or valgrind is monitoring
249 the process we need to free all resources that are part of the
250 process in order to provide the consistency required to track
251 memory leaks.
252
253 A single public API exists and is __libc_freeres(), and this is used
254 by applications like valgrind to freee resouces.
255
256 There are 3 cases:
257
258 (a) __libc_freeres
259
260 In this case all you need to do is define the freeing routine:
261
262 foo.c:
263 libfoo_freeres_fn (foo_freeres)
264 {
265 complex_free (mem);
266 }
267
268 This ensures the function is called at the right point to free
269 resources.
270
271 (b) __libc_freeres_ptr
272
273 The framework for (a) iterates over the list of pointers-to-free
274 in (b) and frees them.
275
276 foo.c:
277 libc_freeres_ptr (static char *foo_buffer);
278
279 Freeing these resources alaways happens last and is equivalent
280 to registering a function that does 'free (foo_buffer)'.
281
282 (c) Explicit lists of free routines to call or objects to free.
283
284 It is the intended goal to remove (a) and (b) which have some
285 non-determinism based on link order, and instead use explicit
286 lists of functions and frees to resolve cleanup ordering issues
287 and make it easy to debug and maintain.
288
289 As of today the following subsystems use (c):
290
291 Per-thread cleanup:
292 * malloc/thread-freeres.c
293
294 libdl cleanup:
295 * dlfcn/dlfreeres.c
296
297 libpthread cleanup:
298 * nptl/nptlfreeres.c
299
300 So if you need any shutdown routines to run you should add them
301 directly to the appropriate subsystem's shutdown list. */
302
303/* Resource pointers to free in libc.so. */
304#define libc_freeres_ptr(decl) \
305 __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
306 decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
307
308/* Resource freeing functions from libc.so go in this section. */
309#define __libc_freeres_fn_section \
310 __attribute__ ((__used__, section ("__libc_freeres_fn")))
311
312/* Resource freeing functions for libc.so. */
313#define libc_freeres_fn(name) \
314 static void name (void) __attribute_used__ __libc_freeres_fn_section; \
315 text_set_element (__libc_subfreeres, name); \
316 static void name (void)
317
318/* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
319 alias to ORIGINAL, when the assembler supports such declarations
320 (such as in ELF).
321 This is only necessary when defining something in assembly, or playing
322 funny alias games where the size should be other than what the compiler
323 thinks it is. */
324#define declare_symbol_alias(symbol, original, type, size) \
325 declare_symbol_alias_1 (symbol, original, type, size)
326#ifdef __ASSEMBLER__
327# define declare_symbol_alias_1(symbol, original, type, size) \
328 strong_alias (original, symbol); \
329 .type C_SYMBOL_NAME (symbol), %##type; \
330 .size C_SYMBOL_NAME (symbol), size
331#else /* Not __ASSEMBLER__. */
332# define declare_symbol_alias_1(symbol, original, type, size) \
333 asm (".globl " __SYMBOL_PREFIX #symbol \
334 "\n\t" declare_symbol_alias_1_alias (symbol, original) \
335 "\n\t.type " __SYMBOL_PREFIX #symbol ", " \
336 "%" #type \
337 "\n\t.size " __SYMBOL_PREFIX #symbol ", " #size);
338# ifdef HAVE_ASM_SET_DIRECTIVE
339# define declare_symbol_alias_1_alias(symbol, original) \
340 ".set " __SYMBOL_PREFIX #symbol ", " __SYMBOL_PREFIX #original
341# else
342# define declare_symbol_alias_1_alias(symbol, original) \
343 __SYMBOL_PREFIX #symbol " = " __SYMBOL_PREFIX #original
344# endif /* HAVE_ASM_SET_DIRECTIVE */
345#endif /* __ASSEMBLER__ */
346
347
348/*
349
350*/
351
352/* Symbol set support macros. */
353
354/* Make SYMBOL, which is in the text segment, an element of SET. */
355#define text_set_element(set, symbol) _elf_set_element(set, symbol)
356/* Make SYMBOL, which is in the data segment, an element of SET. */
357#define data_set_element(set, symbol) _elf_set_element(set, symbol)
358/* Make SYMBOL, which is in the bss segment, an element of SET. */
359#define bss_set_element(set, symbol) _elf_set_element(set, symbol)
360
361/* These are all done the same way in ELF.
362 There is a new section created for each set. */
363#ifdef SHARED
364/* When building a shared library, make the set section writable,
365 because it will need to be relocated at run time anyway. */
366# define _elf_set_element(set, symbol) \
367 static const void *__elf_set_##set##_element_##symbol##__ \
368 __attribute__ ((used, section (#set))) = &(symbol)
369#else
370# define _elf_set_element(set, symbol) \
371 static const void *const __elf_set_##set##_element_##symbol##__ \
372 __attribute__ ((used, section (#set))) = &(symbol)
373#endif
374
375/* Define SET as a symbol set. This may be required (it is in a.out) to
376 be able to use the set's contents. */
377#define symbol_set_define(set) symbol_set_declare(set)
378
379/* Declare SET for use in this module, if defined in another module.
380 In a shared library, this is always local to that shared object.
381 For static linking, the set might be wholly absent and so we use
382 weak references. */
383#define symbol_set_declare(set) \
384 extern char const __start_##set[] __symbol_set_attribute; \
385 extern char const __stop_##set[] __symbol_set_attribute;
386#ifdef SHARED
387# define __symbol_set_attribute attribute_hidden
388#else
389# define __symbol_set_attribute __attribute__ ((weak))
390#endif
391
392/* Return a pointer (void *const *) to the first element of SET. */
393#define symbol_set_first_element(set) ((void *const *) (&__start_##set))
394
395/* Return true iff PTR (a void *const *) has been incremented
396 past the last element in SET. */
397#define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
398
399/* Use symbol_version_reference to specify the version a symbol
400 reference should link to. Use symbol_version or
401 default_symbol_version for the definition of a versioned symbol.
402 The difference is that the latter is a no-op in non-shared
403 builds. */
404#ifdef __ASSEMBLER__
405# define symbol_version_reference(real, name, version) \
406 .symver real, name##@##version
407#else /* !__ASSEMBLER__ */
408# define symbol_version_reference(real, name, version) \
409 __asm__ (".symver " #real "," #name "@" #version)
410#endif
411
412#ifdef SHARED
413# define symbol_version(real, name, version) \
414 symbol_version_reference(real, name, version)
415# define default_symbol_version(real, name, version) \
416 _default_symbol_version(real, name, version)
417# ifdef __ASSEMBLER__
418# define _default_symbol_version(real, name, version) \
419 .symver real, name##@##@##version
420# else
421# define _default_symbol_version(real, name, version) \
422 __asm__ (".symver " #real "," #name "@@" #version)
423# endif
424
425/* Evalutes to a string literal for VERSION in LIB. */
426# define symbol_version_string(lib, version) \
427 _symbol_version_stringify_1 (VERSION_##lib##_##version)
428# define _symbol_version_stringify_1(arg) _symbol_version_stringify_2 (arg)
429# define _symbol_version_stringify_2(arg) #arg
430
431#else /* !SHARED */
432# define symbol_version(real, name, version)
433# define default_symbol_version(real, name, version) \
434 strong_alias(real, name)
435#endif
436
437#if defined SHARED || defined LIBC_NONSHARED \
438 || (BUILD_PIE_DEFAULT && IS_IN (libc))
439# define attribute_hidden __attribute__ ((visibility ("hidden")))
440#else
441# define attribute_hidden
442#endif
443
444#define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
445
446#define attribute_relro __attribute__ ((section (".data.rel.ro")))
447
448
449/* Used to disable stack protection in sensitive places, like ifunc
450 resolvers and early static TLS init. */
451#ifdef HAVE_CC_NO_STACK_PROTECTOR
452# define inhibit_stack_protector \
453 __attribute__ ((__optimize__ ("-fno-stack-protector")))
454#else
455# define inhibit_stack_protector
456#endif
457
458/* The following macros are used for PLT bypassing within libc.so
459 (and if needed other libraries similarly).
460 First of all, you need to have the function prototyped somewhere,
461 say in foo/foo.h:
462
463 int foo (int __bar);
464
465 If calls to foo within libc.so should always go to foo defined in libc.so,
466 then in include/foo.h you add:
467
468 libc_hidden_proto (foo)
469
470 line and after the foo function definition:
471
472 int foo (int __bar)
473 {
474 return __bar;
475 }
476 libc_hidden_def (foo)
477
478 or
479
480 int foo (int __bar)
481 {
482 return __bar;
483 }
484 libc_hidden_weak (foo)
485
486 Similarly for global data. If references to foo within libc.so should
487 always go to foo defined in libc.so, then in include/foo.h you add:
488
489 libc_hidden_proto (foo)
490
491 line and after foo's definition:
492
493 int foo = INITIAL_FOO_VALUE;
494 libc_hidden_data_def (foo)
495
496 or
497
498 int foo = INITIAL_FOO_VALUE;
499 libc_hidden_data_weak (foo)
500
501 If foo is normally just an alias (strong or weak) to some other function,
502 you should use the normal strong_alias first, then add libc_hidden_def
503 or libc_hidden_weak:
504
505 int baz (int __bar)
506 {
507 return __bar;
508 }
509 strong_alias (baz, foo)
510 libc_hidden_weak (foo)
511
512 If the function should be internal to multiple objects, say ld.so and
513 libc.so, the best way is to use:
514
515 #if IS_IN (libc) || IS_IN (rtld)
516 hidden_proto (foo)
517 #endif
518
519 in include/foo.h and the normal macros at all function definitions
520 depending on what DSO they belong to.
521
522 If versioned_symbol macro is used to define foo,
523 libc_hidden_ver macro should be used, as in:
524
525 int __real_foo (int __bar)
526 {
527 return __bar;
528 }
529 versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
530 libc_hidden_ver (__real_foo, foo) */
531
532#if defined SHARED && !defined NO_HIDDEN
533# ifndef __ASSEMBLER__
534# define __hidden_proto_hiddenattr(attrs...) \
535 __attribute__ ((visibility ("hidden"), ##attrs))
536# define hidden_proto(name, attrs...) \
537 __hidden_proto (name, , __GI_##name, ##attrs)
538# define hidden_tls_proto(name, attrs...) \
539 __hidden_proto (name, __thread, __GI_##name, ##attrs)
540# define __hidden_proto(name, thread, internal, attrs...) \
541 extern thread __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
542 __hidden_proto_hiddenattr (attrs);
543# define __hidden_asmname(name) \
544 __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
545# define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
546# define __hidden_asmname2(prefix, name) #prefix name
547# define __hidden_ver1(local, internal, name) \
548 __hidden_ver2 (, local, internal, name)
549# define __hidden_ver2(thread, local, internal, name) \
550 extern thread __typeof (name) __EI_##name \
551 __asm__(__hidden_asmname (#internal)); \
552 extern thread __typeof (name) __EI_##name \
553 __attribute__((alias (__hidden_asmname (#local)))) \
554 __attribute_copy__ (name)
555# define hidden_ver(local, name) __hidden_ver1(local, __GI_##name, name);
556# define hidden_data_ver(local, name) hidden_ver(local, name)
557# define hidden_def(name) __hidden_ver1(__GI_##name, name, name);
558# define hidden_data_def(name) hidden_def(name)
559# define hidden_tls_def(name) \
560 __hidden_ver2 (__thread, __GI_##name, name, name);
561# define hidden_weak(name) \
562 __hidden_ver1(__GI_##name, name, name) __attribute__((weak));
563# define hidden_data_weak(name) hidden_weak(name)
564# define hidden_nolink(name, lib, version) \
565 __hidden_nolink1 (__GI_##name, __EI_##name, name, VERSION_##lib##_##version)
566# define __hidden_nolink1(local, internal, name, version) \
567 __hidden_nolink2 (local, internal, name, version)
568# define __hidden_nolink2(local, internal, name, version) \
569 extern __typeof (name) internal __attribute__ ((alias (#local))) \
570 __attribute_copy__ (name); \
571 __hidden_nolink3 (local, internal, #name "@" #version)
572# define __hidden_nolink3(local, internal, vername) \
573 __asm__ (".symver " #internal ", " vername);
574# else
575/* For assembly, we need to do the opposite of what we do in C:
576 in assembly gcc __REDIRECT stuff is not in place, so functions
577 are defined by its normal name and we need to create the
578 __GI_* alias to it, in C __REDIRECT causes the function definition
579 to use __GI_* name and we need to add alias to the real name.
580 There is no reason to use hidden_weak over hidden_def in assembly,
581 but we provide it for consistency with the C usage.
582 hidden_proto doesn't make sense for assembly but the equivalent
583 is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET. */
584# define hidden_def(name) strong_alias (name, __GI_##name)
585# define hidden_weak(name) hidden_def (name)
586# define hidden_ver(local, name) strong_alias (local, __GI_##name)
587# define hidden_data_def(name) strong_data_alias (name, __GI_##name)
588# define hidden_tls_def(name) hidden_data_def (name)
589# define hidden_data_weak(name) hidden_data_def (name)
590# define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
591# define HIDDEN_JUMPTARGET(name) __GI_##name
592# endif
593#else
594# ifndef __ASSEMBLER__
595# if !defined SHARED && IS_IN (libc) && !defined LIBC_NONSHARED \
596 && (!defined PIC || !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE) \
597 && !defined NO_HIDDEN
598# define __hidden_proto_hiddenattr(attrs...) \
599 __attribute__ ((visibility ("hidden"), ##attrs))
600# define hidden_proto(name, attrs...) \
601 __hidden_proto (name, , name, ##attrs)
602# define hidden_tls_proto(name, attrs...) \
603 __hidden_proto (name, __thread, name, ##attrs)
604# define __hidden_proto(name, thread, internal, attrs...) \
605 extern thread __typeof (name) name __hidden_proto_hiddenattr (attrs);
606# else
607# define hidden_proto(name, attrs...)
608# define hidden_tls_proto(name, attrs...)
609# endif
610# else
611# define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
612# endif /* Not __ASSEMBLER__ */
613# define hidden_weak(name)
614# define hidden_def(name)
615# define hidden_ver(local, name)
616# define hidden_data_weak(name)
617# define hidden_data_def(name)
618# define hidden_tls_def(name)
619# define hidden_data_ver(local, name)
620# define hidden_nolink(name, lib, version)
621#endif
622
623#if IS_IN (libc)
624# define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
625# define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
626# define libc_hidden_def(name) hidden_def (name)
627# define libc_hidden_weak(name) hidden_weak (name)
628# define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
629# define libc_hidden_ver(local, name) hidden_ver (local, name)
630# define libc_hidden_data_def(name) hidden_data_def (name)
631# define libc_hidden_tls_def(name) hidden_tls_def (name)
632# define libc_hidden_data_weak(name) hidden_data_weak (name)
633# define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
634#else
635# define libc_hidden_proto(name, attrs...)
636# define libc_hidden_tls_proto(name, attrs...)
637# define libc_hidden_def(name)
638# define libc_hidden_weak(name)
639# define libc_hidden_ver(local, name)
640# define libc_hidden_data_def(name)
641# define libc_hidden_tls_def(name)
642# define libc_hidden_data_weak(name)
643# define libc_hidden_data_ver(local, name)
644#endif
645
646#if IS_IN (rtld)
647# define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
648# define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
649# define rtld_hidden_def(name) hidden_def (name)
650# define rtld_hidden_weak(name) hidden_weak (name)
651# define rtld_hidden_ver(local, name) hidden_ver (local, name)
652# define rtld_hidden_data_def(name) hidden_data_def (name)
653# define rtld_hidden_tls_def(name) hidden_tls_def (name)
654# define rtld_hidden_data_weak(name) hidden_data_weak (name)
655# define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
656#else
657# define rtld_hidden_proto(name, attrs...)
658# define rtld_hidden_tls_proto(name, attrs...)
659# define rtld_hidden_def(name)
660# define rtld_hidden_weak(name)
661# define rtld_hidden_ver(local, name)
662# define rtld_hidden_data_def(name)
663# define rtld_hidden_tls_def(name)
664# define rtld_hidden_data_weak(name)
665# define rtld_hidden_data_ver(local, name)
666#endif
667
668#if IS_IN (libm)
669# define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
670# define libm_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
671# define libm_hidden_def(name) hidden_def (name)
672# define libm_hidden_weak(name) hidden_weak (name)
673# define libm_hidden_ver(local, name) hidden_ver (local, name)
674# define libm_hidden_data_def(name) hidden_data_def (name)
675# define libm_hidden_tls_def(name) hidden_tls_def (name)
676# define libm_hidden_data_weak(name) hidden_data_weak (name)
677# define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
678#else
679# define libm_hidden_proto(name, attrs...)
680# define libm_hidden_tls_proto(name, attrs...)
681# define libm_hidden_def(name)
682# define libm_hidden_weak(name)
683# define libm_hidden_ver(local, name)
684# define libm_hidden_data_def(name)
685# define libm_hidden_tls_def(name)
686# define libm_hidden_data_weak(name)
687# define libm_hidden_data_ver(local, name)
688#endif
689
690#if IS_IN (libmvec)
691# define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
692# define libmvec_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
693# define libmvec_hidden_def(name) hidden_def (name)
694# define libmvec_hidden_weak(name) hidden_weak (name)
695# define libmvec_hidden_ver(local, name) hidden_ver (local, name)
696# define libmvec_hidden_data_def(name) hidden_data_def (name)
697# define libmvec_hidden_tls_def(name) hidden_tls_def (name)
698# define libmvec_hidden_data_weak(name) hidden_data_weak (name)
699# define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
700#else
701# define libmvec_hidden_proto(name, attrs...)
702# define libmvec_hidden_tls_proto(name, attrs...)
703# define libmvec_hidden_def(name)
704# define libmvec_hidden_weak(name)
705# define libmvec_hidden_ver(local, name)
706# define libmvec_hidden_data_def(name)
707# define libmvec_hidden_tls_def(name)
708# define libmvec_hidden_data_weak(name)
709# define libmvec_hidden_data_ver(local, name)
710#endif
711
712#if IS_IN (libresolv)
713# define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
714# define libresolv_hidden_tls_proto(name, attrs...) \
715 hidden_tls_proto (name, ##attrs)
716# define libresolv_hidden_def(name) hidden_def (name)
717# define libresolv_hidden_weak(name) hidden_weak (name)
718# define libresolv_hidden_ver(local, name) hidden_ver (local, name)
719# define libresolv_hidden_data_def(name) hidden_data_def (name)
720# define libresolv_hidden_tls_def(name) hidden_tls_def (name)
721# define libresolv_hidden_data_weak(name) hidden_data_weak (name)
722# define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
723#else
724# define libresolv_hidden_proto(name, attrs...)
725# define libresolv_hidden_tls_proto(name, attrs...)
726# define libresolv_hidden_def(name)
727# define libresolv_hidden_weak(name)
728# define libresolv_hidden_ver(local, name)
729# define libresolv_hidden_data_def(name)
730# define libresolv_hidden_tls_def(name)
731# define libresolv_hidden_data_weak(name)
732# define libresolv_hidden_data_ver(local, name)
733#endif
734
735#if IS_IN (libpthread)
736# define libpthread_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
737# define libpthread_hidden_tls_proto(name, attrs...) \
738 hidden_tls_proto (name, ##attrs)
739# define libpthread_hidden_def(name) hidden_def (name)
740# define libpthread_hidden_weak(name) hidden_weak (name)
741# define libpthread_hidden_ver(local, name) hidden_ver (local, name)
742# define libpthread_hidden_data_def(name) hidden_data_def (name)
743# define libpthread_hidden_tls_def(name) hidden_tls_def (name)
744# define libpthread_hidden_data_weak(name) hidden_data_weak (name)
745# define libpthread_hidden_data_ver(local, name) hidden_data_ver (local, name)
746#else
747# define libpthread_hidden_proto(name, attrs...)
748# define libpthread_hidden_tls_proto(name, attrs...)
749# define libpthread_hidden_def(name)
750# define libpthread_hidden_weak(name)
751# define libpthread_hidden_ver(local, name)
752# define libpthread_hidden_data_def(name)
753# define libpthread_hidden_tls_def(name)
754# define libpthread_hidden_data_weak(name)
755# define libpthread_hidden_data_ver(local, name)
756#endif
757
758#if IS_IN (librt)
759# define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
760# define librt_hidden_tls_proto(name, attrs...) \
761 hidden_tls_proto (name, ##attrs)
762# define librt_hidden_def(name) hidden_def (name)
763# define librt_hidden_weak(name) hidden_weak (name)
764# define librt_hidden_ver(local, name) hidden_ver (local, name)
765# define librt_hidden_data_def(name) hidden_data_def (name)
766# define librt_hidden_tls_def(name) hidden_tls_def (name)
767# define librt_hidden_data_weak(name) hidden_data_weak (name)
768# define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
769#else
770# define librt_hidden_proto(name, attrs...)
771# define librt_hidden_tls_proto(name, attrs...)
772# define librt_hidden_def(name)
773# define librt_hidden_weak(name)
774# define librt_hidden_ver(local, name)
775# define librt_hidden_data_def(name)
776# define librt_hidden_tls_def(name)
777# define librt_hidden_data_weak(name)
778# define librt_hidden_data_ver(local, name)
779#endif
780
781#if IS_IN (libdl)
782# define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
783# define libdl_hidden_tls_proto(name, attrs...) \
784 hidden_tls_proto (name, ##attrs)
785# define libdl_hidden_def(name) hidden_def (name)
786# define libdl_hidden_weak(name) hidden_weak (name)
787# define libdl_hidden_ver(local, name) hidden_ver (local, name)
788# define libdl_hidden_data_def(name) hidden_data_def (name)
789# define libdl_hidden_tls_def(name) hidden_tls_def (name)
790# define libdl_hidden_data_weak(name) hidden_data_weak (name)
791# define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
792#else
793# define libdl_hidden_proto(name, attrs...)
794# define libdl_hidden_tls_proto(name, attrs...)
795# define libdl_hidden_def(name)
796# define libdl_hidden_weak(name)
797# define libdl_hidden_ver(local, name)
798# define libdl_hidden_data_def(name)
799# define libdl_hidden_tls_def(name)
800# define libdl_hidden_data_weak(name)
801# define libdl_hidden_data_ver(local, name)
802#endif
803
804#if IS_IN (libnss_files)
805# define libnss_files_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
806# define libnss_files_hidden_tls_proto(name, attrs...) \
807 hidden_tls_proto (name, ##attrs)
808# define libnss_files_hidden_def(name) hidden_def (name)
809# define libnss_files_hidden_weak(name) hidden_weak (name)
810# define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
811# define libnss_files_hidden_data_def(name) hidden_data_def (name)
812# define libnss_files_hidden_tls_def(name) hidden_tls_def (name)
813# define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
814# define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
815#else
816# define libnss_files_hidden_proto(name, attrs...)
817# define libnss_files_hidden_tls_proto(name, attrs...)
818# define libnss_files_hidden_def(name)
819# define libnss_files_hidden_weak(name)
820# define libnss_files_hidden_ver(local, name)
821# define libnss_files_hidden_data_def(name)
822# define libnss_files_hidden_tls_def(name)
823# define libnss_files_hidden_data_weak(name)
824# define libnss_files_hidden_data_ver(local, name)
825#endif
826
827#if IS_IN (libnsl)
828# define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
829# define libnsl_hidden_tls_proto(name, attrs...) \
830 hidden_tls_proto (name, ##attrs)
831# define libnsl_hidden_nolink_def(name, version) hidden_nolink (name, libnsl, version)
832# define libnsl_hidden_weak(name) hidden_weak (name)
833# define libnsl_hidden_ver(local, name) hidden_ver (local, name)
834# define libnsl_hidden_data_def(name) hidden_data_def (name)
835# define libnsl_hidden_tls_def(name) hidden_tls_def (name)
836# define libnsl_hidden_data_weak(name) hidden_data_weak (name)
837# define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
838#else
839# define libnsl_hidden_proto(name, attrs...)
840# define libnsl_hidden_tls_proto(name, attrs...)
841# define libnsl_hidden_weak(name)
842# define libnsl_hidden_ver(local, name)
843# define libnsl_hidden_data_def(name)
844# define libnsl_hidden_tls_def(name)
845# define libnsl_hidden_data_weak(name)
846# define libnsl_hidden_data_ver(local, name)
847#endif
848
849#define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
850#define libc_hidden_builtin_def(name) libc_hidden_def (name)
851#define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
852#define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
853
854#define libc_hidden_ldbl_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
855#ifdef __ASSEMBLER__
856# define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
857#endif
858
859#if IS_IN (libutil)
860# define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
861# define libutil_hidden_tls_proto(name, attrs...) \
862 hidden_tls_proto (name, ##attrs)
863# define libutil_hidden_def(name) hidden_def (name)
864# define libutil_hidden_weak(name) hidden_weak (name)
865# define libutil_hidden_ver(local, name) hidden_ver (local, name)
866# define libutil_hidden_data_def(name) hidden_data_def (name)
867# define libutil_hidden_tls_def(name) hidden_tls_def (name)
868# define libutil_hidden_data_weak(name) hidden_data_weak (name)
869# define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
870#else
871# define libutil_hidden_proto(name, attrs...)
872# define libutil_hidden_tls_proto(name, attrs...)
873# define libutil_hidden_def(name)
874# define libutil_hidden_weak(name)
875# define libutil_hidden_ver(local, name)
876# define libutil_hidden_data_def(name)
877# define libutil_hidden_tls_def(name)
878# define libutil_hidden_data_weak(name)
879# define libutil_hidden_data_ver(local, name)
880#endif
881
882#if IS_IN (libanl)
883# define libanl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
884# define libanl_hidden_def(name) hidden_def (name)
885#else
886# define libanl_hidden_proto(name, attrs...)
887# define libanl_hidden_def(name)
888#endif
889
890/* Get some dirty hacks. */
891#include <symbol-hacks.h>
892
893/* Move compatibility symbols out of the way by placing them all in a
894 special section. */
895#ifndef __ASSEMBLER__
896# define attribute_compat_text_section \
897 __attribute__ ((section (".text.compat")))
898# define attribute_compat_data_section \
899 __attribute__ ((section (".data.compat")))
900#else
901# define compat_text_section .section ".text.compat", "ax";
902# define compat_data_section .section ".data.compat", "aw";
903#endif
904
905/* Helper / base macros for indirect function symbols. */
906#define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \
907 classifier inhibit_stack_protector \
908 __typeof (type_name) *name##_ifunc (arg) \
909 { \
910 init (); \
911 __typeof (type_name) *res = expr; \
912 return res; \
913 }
914
915#ifdef HAVE_GCC_IFUNC
916# define __ifunc(type_name, name, expr, arg, init) \
917 extern __typeof (type_name) name __attribute__ \
918 ((ifunc (#name "_ifunc"))); \
919 __ifunc_resolver (type_name, name, expr, arg, init, static)
920
921# define __ifunc_hidden(type_name, name, expr, arg, init) \
922 __ifunc (type_name, name, expr, arg, init)
923#else
924/* Gcc does not support __attribute__ ((ifunc (...))). Use the old behaviour
925 as fallback. But keep in mind that the debug information for the ifunc
926 resolver functions is not correct. It contains the ifunc'ed function as
927 DW_AT_linkage_name. E.g. lldb uses this field and an inferior function
928 call of the ifunc'ed function will fail due to "no matching function for
929 call to ..." because the ifunc'ed function and the resolver function have
930 different signatures. (Gcc support is disabled at least on a ppc64le
931 Ubuntu 14.04 system.) */
932
933# define __ifunc(type_name, name, expr, arg, init) \
934 extern __typeof (type_name) name; \
935 __typeof (type_name) *name##_ifunc (arg) __asm__ (#name); \
936 __ifunc_resolver (type_name, name, expr, arg, init,) \
937 __asm__ (".type " #name ", %gnu_indirect_function");
938
939# define __ifunc_hidden(type_name, name, expr, arg, init) \
940 extern __typeof (type_name) __libc_##name; \
941 __ifunc (type_name, __libc_##name, expr, arg, init) \
942 strong_alias (__libc_##name, name);
943#endif /* !HAVE_GCC_IFUNC */
944
945/* The following macros are used for indirect function symbols in libc.so.
946 First of all, you need to have the function prototyped somewhere,
947 say in foo.h:
948
949 int foo (int __bar);
950
951 If you have an implementation for foo which e.g. uses a special hardware
952 feature which isn't available on all machines where this libc.so will be
953 used but decideable if available at runtime e.g. via hwcaps, you can provide
954 two or multiple implementations of foo:
955
956 int __foo_default (int __bar)
957 {
958 return __bar;
959 }
960
961 int __foo_special (int __bar)
962 {
963 return __bar;
964 }
965
966 If your function foo has no libc_hidden_proto (foo) defined for PLT
967 bypassing, you can use:
968
969 #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
970
971 libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
972
973 This will define a resolver function for foo which returns __foo_special or
974 __foo_default depending on your specified expression. Please note that you
975 have to define a macro function INIT_ARCH before using libc_ifunc macro as
976 it is called by the resolver function before evaluating the specified
977 expression. In this example it is used to prepare the hwcap variable.
978 The resolver function is assigned to an ifunc'ed symbol foo. Calls to foo
979 from inside or outside of libc.so will be indirected by a PLT call.
980
981 If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
982 and calls to foo within libc.so should always go to one specific
983 implementation of foo e.g. __foo_default then you have to add:
984
985 __hidden_ver1 (__foo_default, __GI_foo, __foo_default);
986
987 or a tweaked definition of libc_hidden_def macro after the __foo_default
988 function definition. Calls to foo within libc.so will always go directly to
989 __foo_default. Calls to foo from outside libc.so will be indirected by a
990 PLT call to ifunc'ed symbol foo which you have to define in a separate
991 compile unit:
992
993 #define foo __redirect_foo
994 #include <foo.h>
995 #undef foo
996
997 extern __typeof (__redirect_foo) __foo_default attribute_hidden;
998 extern __typeof (__redirect_foo) __foo_special attribute_hidden;
999
1000 libc_ifunc_redirected (__redirect_foo, foo,
1001 (hwcap & HWCAP_SPECIAL)
1002 ? __foo_special
1003 : __foo_default);
1004
1005 This will define the ifunc'ed symbol foo like above. The redirection of foo
1006 in header file is needed to omit an additional defintion of __GI_foo which
1007 would end in a linker error while linking libc.so. You have to specify
1008 __redirect_foo as first parameter which is used within libc_ifunc_redirected
1009 macro in conjunction with typeof to define the ifunc'ed symbol foo.
1010
1011 If your function foo has a libc_hidden_proto (foo) defined and calls to foo
1012 within or from outside libc.so should go via ifunc'ed symbol, then you have
1013 to use:
1014
1015 libc_ifunc_hidden (foo, foo,
1016 (hwcap & HWCAP_SPECIAL)
1017 ? __foo_special
1018 : __foo_default);
1019 libc_hidden_def (foo)
1020
1021 The first parameter foo of libc_ifunc_hidden macro is used in the same way
1022 as for libc_ifunc_redirected macro. */
1023
1024#define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
1025
1026#define libc_ifunc_redirected(redirected_name, name, expr) \
1027 __ifunc (redirected_name, name, expr, void, INIT_ARCH)
1028
1029#define libc_ifunc_hidden(redirected_name, name, expr) \
1030 __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
1031
1032/* The body of the function is supposed to use __get_cpu_features
1033 which will, if necessary, initialize the data first. */
1034#define libm_ifunc_init()
1035#define libm_ifunc(name, expr) \
1036 __ifunc (name, name, expr, void, libm_ifunc_init)
1037
1038/* Add the compiler optimization to inhibit loop transformation to library
1039 calls. This is used to avoid recursive calls in memset and memmove
1040 default implementations. */
1041#ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
1042# define inhibit_loop_to_libcall \
1043 __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
1044#else
1045# define inhibit_loop_to_libcall
1046#endif
1047
1048/* These macros facilitate sharing source files with gnulib.
1049
1050 They are here instead of sys/cdefs.h because they should not be
1051 used in public header files.
1052
1053 Their definitions should be kept consistent with the definitions in
1054 gnulib-common.m4, but it is not necessary to cater to old non-GCC
1055 compilers, since they will only be used while building glibc itself.
1056 (Note that _GNUC_PREREQ cannot be used in this file.) */
1057
1058/* Define as a marker that can be attached to declarations that might not
1059 be used. This helps to reduce warnings, such as from
1060 GCC -Wunused-parameter. */
1061#if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
1062# define _GL_UNUSED __attribute__ ((__unused__))
1063#else
1064# define _GL_UNUSED
1065#endif
1066
1067/* gcc supports the "unused" attribute on possibly unused labels, and
1068 g++ has since version 4.5. Note to support C++ as well as C,
1069 _GL_UNUSED_LABEL should be used with a trailing ; */
1070#if !defined __cplusplus || __GNUC__ > 4 \
1071 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
1072# define _GL_UNUSED_LABEL _GL_UNUSED
1073#else
1074# define _GL_UNUSED_LABEL
1075#endif
1076
1077/* The __pure__ attribute was added in gcc 2.96. */
1078#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
1079# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
1080#else
1081# define _GL_ATTRIBUTE_PURE /* empty */
1082#endif
1083
1084/* The __const__ attribute was added in gcc 2.95. */
1085#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
1086# define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
1087#else
1088# define _GL_ATTRIBUTE_CONST /* empty */
1089#endif
1090
1091#endif /* !_ISOMAC */
1092#endif /* libc-symbols.h */
1093