include/libc-symbols.h

   1 /* Support macros for making weak and strong aliases for symbols,
   2    and for using symbol sets and linker warnings with GNU ld.
   3    Copyright (C) 1995-2017 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef _LIBC_SYMBOLS_H
  21 #define _LIBC_SYMBOLS_H 1
  22
  23 /* This file is included implicitly in the compilation of every source file,
  24    using -include.  It includes config.h.  */
  25
  26 /* Enable declarations of GNU extensions, since we are compiling them.  */
  27 #define _GNU_SOURCE 1
  28
  29 #ifdef MODULE_NAME
  30
  31 /* Use `#if IS_IN (module)` to detect what component is being compiled.  */
  32 #define PASTE_NAME1(a,b) a##b
  33 #define PASTE_NAME(a,b)  PASTE_NAME1 (a,b)
  34 #define IN_MODULE        PASTE_NAME (MODULE_, MODULE_NAME)
  35 #define IS_IN(lib)       (IN_MODULE == MODULE_##lib)
  36
  37 /* True if the current module is a versioned library.  Versioned
  38    library names culled from shlib-versions files are assigned a
  39    MODULE_* value greater than MODULE_LIBS_BEGIN.  */
  40 #define IS_IN_LIB        (IN_MODULE > MODULE_LIBS_BEGIN)
  41
  42 /* The testsuite, and some other ancillary code, should be compiled against
  43    as close an approximation to the installed headers as possible.
  44    Defining this symbol disables most internal-use-only declarations
  45    provided by this header, and all those provided by other internal
  46    wrapper headers.  */
  47 #if IS_IN (testsuite) || defined IS_IN_build || defined __cplusplus
  48 # define _ISOMAC 1
  49 #endif
  50
  51 #else
  52 /* The generation process for a few files created very early in the
  53    build (notably libc-modules.h itself) involves preprocessing this
  54    header without defining MODULE_NAME.  Under these conditions,
  55    internal declarations (especially from config.h) must be visible,
  56    but IS_IN should always evaluate as false.  */
  57 # define IS_IN(lib) 0
  58 # define IS_IN_LIB 0
  59 # define IN_MODULE (-1)
  60 #endif
  61
  62 #ifndef _ISOMAC
  63
  64 /* This is defined for the compilation of all C library code.  features.h
  65    tests this to avoid inclusion of stubs.h while compiling the library,
  66    before stubs.h has been generated.  Some library code that is shared
  67    with other packages also tests this symbol to see if it is being
  68    compiled as part of the C library.  We must define this before including
  69    config.h, because it makes some definitions conditional on whether libc
  70    itself is being compiled, or just some generator program.  */
  71 #define _LIBC   1
  72
  73 /* Some files must be compiled with optimization on.  */
  74 #if !defined __ASSEMBLER__ && !defined __OPTIMIZE__
  75 # error "glibc cannot be compiled without optimization"
  76 #endif
  77
  78 /* -ffast-math cannot be applied to the C library, as it alters the ABI.
  79    Some test components that use -ffast-math are currently not part of
  80    IS_IN (testsuite) for technical reasons, so we have a secondary override.  */
  81 #if defined __FAST_MATH__ && !defined TEST_FAST_MATH
  82 # error "glibc must not be compiled with -ffast-math"
  83 #endif
  84
  85 #include <config.h>
  86
  87 /* When PIC is defined and SHARED isn't defined, we are building PIE
  88    by default.  */
  89 #if defined PIC && !defined SHARED
  90 # define BUILD_PIE_DEFAULT 1
  91 #else
  92 # define BUILD_PIE_DEFAULT 0
  93 #endif
  94
  95 /* Define this for the benefit of portable GNU code that wants to check it.
  96    Code that checks with #if will not #include <config.h> again, since we've
  97    already done it (and this file is implicitly included in every compile,
  98    via -include).  Code that checks with #ifdef will #include <config.h>,
  99    but that file should always be idempotent (i.e., it's just #define/#undef
 100    and nothing else anywhere should be changing the macro state it touches),
 101    so it's harmless.  */
 102 #define HAVE_CONFIG_H   0
 103
 104 /* Define these macros for the benefit of portable GNU code that wants to check
 105    them.  Of course, STDC_HEADERS is never false when building libc!  */
 106 #define STDC_HEADERS    1
 107 #define HAVE_MBSTATE_T  1
 108 #define HAVE_MBSRTOWCS  1
 109 #define HAVE_LIBINTL_H  1
 110 #define HAVE_WCTYPE_H   1
 111 #define HAVE_ISWCTYPE   1
 112 #define ENABLE_NLS      1
 113
 114 /* The symbols in all the user (non-_) macros are C symbols.  */
 115
 116 #ifndef __SYMBOL_PREFIX
 117 # define __SYMBOL_PREFIX
 118 #endif
 119
 120 #ifndef C_SYMBOL_NAME
 121 # define C_SYMBOL_NAME(name) name
 122 #endif
 123
 124 #ifndef ASM_LINE_SEP
 125 # define ASM_LINE_SEP ;
 126 #endif
 127
 128 #ifndef __ASSEMBLER__
 129 /* GCC understands weak symbols and aliases; use its interface where
 130    possible, instead of embedded assembly language.  */
 131
 132 /* Define ALIASNAME as a strong alias for NAME.  */
 133 # define strong_alias(name, aliasname) _strong_alias(name, aliasname)
 134 # define _strong_alias(name, aliasname) \
 135   extern __typeof (name) aliasname __attribute__ ((alias (#name)));
 136
 137 /* This comes between the return type and function name in
 138    a function definition to make that definition weak.  */
 139 # define weak_function __attribute__ ((weak))
 140 # define weak_const_function __attribute__ ((weak, __const__))
 141
 142 /* Define ALIASNAME as a weak alias for NAME.
 143    If weak aliases are not available, this defines a strong alias.  */
 144 # define weak_alias(name, aliasname) _weak_alias (name, aliasname)
 145 # define _weak_alias(name, aliasname) \
 146   extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
 147
 148 /* Same as WEAK_ALIAS, but mark symbol as hidden.  */
 149 # define weak_hidden_alias(name, aliasname) \
 150   _weak_hidden_alias (name, aliasname)
 151 # define _weak_hidden_alias(name, aliasname) \
 152   extern __typeof (name) aliasname \
 153     __attribute__ ((weak, alias (#name), __visibility__ ("hidden")));
 154
 155 /* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined).  */
 156 # define weak_extern(symbol) _weak_extern (weak symbol)
 157 # define _weak_extern(expr) _Pragma (#expr)
 158
 159 /* In shared builds, the expression call_function_static_weak
 160    (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
 161    identifier) unconditionally, with the (potentially empty) argument
 162    list ARGUMENTS.  In static builds, if FUNCTION-SYMBOL has a
 163    definition, the function is invoked as before; if FUNCTION-SYMBOL
 164    is NULL, no call is performed.  */
 165 # ifdef SHARED
 166 #  define call_function_static_weak(func, ...) func (__VA_ARGS__)
 167 # else  /* !SHARED */
 168 #  define call_function_static_weak(func, ...)          \
 169   ({                                                    \
 170     extern __typeof__ (func) func weak_function;        \
 171     (func != NULL ? func (__VA_ARGS__) : (void)0);      \
 172   })
 173 # endif
 174
 175 #else /* __ASSEMBLER__ */
 176
 177 # ifdef HAVE_ASM_SET_DIRECTIVE
 178 #  define strong_alias(original, alias)                         \
 179   .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP             \
 180   .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
 181 #  define strong_data_alias(original, alias) strong_alias(original, alias)
 182 # else
 183 #  define strong_alias(original, alias)                         \
 184   .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP             \
 185   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 186 #  define strong_data_alias(original, alias) strong_alias(original, alias)
 187 # endif
 188
 189 # define weak_alias(original, alias)                                    \
 190   .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP                              \
 191   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 192
 193 # define weak_extern(symbol)                                            \
 194   .weak C_SYMBOL_NAME (symbol)
 195
 196 #endif /* __ASSEMBLER__ */
 197
 198 /* Determine the return address.  */
 199 #define RETURN_ADDRESS(nr) \
 200   __builtin_extract_return_addr (__builtin_return_address (nr))
 201
 202 /* When a reference to SYMBOL is encountered, the linker will emit a
 203    warning message MSG.  */
 204 /* We want the .gnu.warning.SYMBOL section to be unallocated.  */
 205 #define __make_section_unallocated(section_string)      \
 206   asm (".section " section_string "\n\t.previous");
 207
 208 /* Tacking on "\n\t#" to the section name makes gcc put it's bogus
 209    section attributes on what looks like a comment to the assembler.  */
 210 #ifdef HAVE_SECTION_QUOTES
 211 # define __sec_comment "\"\n\t#\""
 212 #else
 213 # define __sec_comment "\n\t#"
 214 #endif
 215 #define link_warning(symbol, msg) \
 216   __make_section_unallocated (".gnu.warning." #symbol) \
 217   static const char __evoke_link_warning_##symbol[]     \
 218     __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
 219     = msg;
 220 #define libc_freeres_ptr(decl) \
 221   __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
 222   decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
 223 #define __libc_freeres_fn_section \
 224   __attribute__ ((section ("__libc_freeres_fn")))
 225
 226 #define libc_freeres_fn(name)   \
 227   static void name (void) __attribute_used__ __libc_freeres_fn_section; \
 228   text_set_element (__libc_subfreeres, name);                           \
 229   static void name (void)
 230
 231 /* A canned warning for sysdeps/stub functions.  */
 232 #define stub_warning(name) \
 233   __make_section_unallocated (".gnu.glibc-stub." #name) \
 234   link_warning (name, #name " is not implemented and will always fail")
 235
 236 /* Warning for linking functions calling dlopen into static binaries.  */
 237 #ifdef SHARED
 238 #define static_link_warning(name)
 239 #else
 240 #define static_link_warning(name) static_link_warning1(name)
 241 #define static_link_warning1(name) \
 242   link_warning(name, "Using '" #name "' in statically linked applications \
 243 requires at runtime the shared libraries from the glibc version used \
 244 for linking")
 245 #endif
 246
 247 /* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
 248    alias to ORIGINAL, when the assembler supports such declarations
 249    (such as in ELF).
 250    This is only necessary when defining something in assembly, or playing
 251    funny alias games where the size should be other than what the compiler
 252    thinks it is.  */
 253 #define declare_symbol_alias(symbol, original, type, size) \
 254   declare_symbol_alias_1 (symbol, original, type, size)
 255 #ifdef __ASSEMBLER__
 256 # define declare_symbol_alias_1(symbol, original, type, size) \
 257    strong_alias (original, symbol); \
 258    .type C_SYMBOL_NAME (symbol), %##type; \
 259    .size C_SYMBOL_NAME (symbol), size
 260 #else /* Not __ASSEMBLER__.  */
 261 # define declare_symbol_alias_1(symbol, original, type, size) \
 262    asm (".globl " __SYMBOL_PREFIX #symbol \
 263         "\n\t" declare_symbol_alias_1_alias (symbol, original) \
 264         "\n\t.type " __SYMBOL_PREFIX #symbol ", " \
 265         "%" #type \
 266         "\n\t.size " __SYMBOL_PREFIX #symbol ", " #size);
 267 # ifdef HAVE_ASM_SET_DIRECTIVE
 268 #  define declare_symbol_alias_1_alias(symbol, original) \
 269      ".set " __SYMBOL_PREFIX #symbol ", " __SYMBOL_PREFIX #original
 270 # else
 271 #  define declare_symbol_alias_1_alias(symbol, original) \
 272      __SYMBOL_PREFIX #symbol " = " __SYMBOL_PREFIX #original
 273 # endif /* HAVE_ASM_SET_DIRECTIVE */
 274 #endif /* __ASSEMBLER__ */
 275
 276
 277 /*
 278 \f
 279 */
 280
 281 /* Symbol set support macros.  */
 282
 283 /* Make SYMBOL, which is in the text segment, an element of SET.  */
 284 #define text_set_element(set, symbol)   _elf_set_element(set, symbol)
 285 /* Make SYMBOL, which is in the data segment, an element of SET.  */
 286 #define data_set_element(set, symbol)   _elf_set_element(set, symbol)
 287 /* Make SYMBOL, which is in the bss segment, an element of SET.  */
 288 #define bss_set_element(set, symbol)    _elf_set_element(set, symbol)
 289
 290 /* These are all done the same way in ELF.
 291    There is a new section created for each set.  */
 292 #ifdef SHARED
 293 /* When building a shared library, make the set section writable,
 294    because it will need to be relocated at run time anyway.  */
 295 # define _elf_set_element(set, symbol) \
 296   static const void *__elf_set_##set##_element_##symbol##__ \
 297     __attribute__ ((used, section (#set))) = &(symbol)
 298 #else
 299 # define _elf_set_element(set, symbol) \
 300   static const void *const __elf_set_##set##_element_##symbol##__ \
 301     __attribute__ ((used, section (#set))) = &(symbol)
 302 #endif
 303
 304 /* Define SET as a symbol set.  This may be required (it is in a.out) to
 305    be able to use the set's contents.  */
 306 #define symbol_set_define(set)  symbol_set_declare(set)
 307
 308 /* Declare SET for use in this module, if defined in another module.
 309    In a shared library, this is always local to that shared object.
 310    For static linking, the set might be wholly absent and so we use
 311    weak references.  */
 312 #define symbol_set_declare(set) \
 313   extern char const __start_##set[] __symbol_set_attribute; \
 314   extern char const __stop_##set[] __symbol_set_attribute;
 315 #ifdef SHARED
 316 # define __symbol_set_attribute attribute_hidden
 317 #else
 318 # define __symbol_set_attribute __attribute__ ((weak))
 319 #endif
 320
 321 /* Return a pointer (void *const *) to the first element of SET.  */
 322 #define symbol_set_first_element(set)   ((void *const *) (&__start_##set))
 323
 324 /* Return true iff PTR (a void *const *) has been incremented
 325    past the last element in SET.  */
 326 #define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
 327
 328 /* Use symbol_version_reference to specify the version a symbol
 329    reference should link to.  Use symbol_version or
 330    default_symbol_version for the definition of a versioned symbol.
 331    The difference is that the latter is a no-op in non-shared
 332    builds.  */
 333 #ifdef __ASSEMBLER__
 334 # define symbol_version_reference(real, name, version) \
 335      .symver real, name##@##version
 336 #else  /* !__ASSEMBLER__ */
 337 # define symbol_version_reference(real, name, version) \
 338   __asm__ (".symver " #real "," #name "@" #version)
 339 #endif
 340
 341 #ifdef SHARED
 342 # define symbol_version(real, name, version) \
 343   symbol_version_reference(real, name, version)
 344 # define default_symbol_version(real, name, version) \
 345      _default_symbol_version(real, name, version)
 346 # ifdef __ASSEMBLER__
 347 #  define _default_symbol_version(real, name, version) \
 348      .symver real, name##@##@##version
 349 # else
 350 #  define _default_symbol_version(real, name, version) \
 351      __asm__ (".symver " #real "," #name "@@" #version)
 352 # endif
 353 #else
 354 # define symbol_version(real, name, version)
 355 # define default_symbol_version(real, name, version) \
 356   strong_alias(real, name)
 357 #endif
 358
 359 #if defined SHARED || defined LIBC_NONSHARED \
 360   || (BUILD_PIE_DEFAULT && IS_IN (libc))
 361 # define attribute_hidden __attribute__ ((visibility ("hidden")))
 362 #else
 363 # define attribute_hidden
 364 #endif
 365
 366 #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
 367
 368 #define attribute_relro __attribute__ ((section (".data.rel.ro")))
 369
 370
 371 /* Used to disable stack protection in sensitive places, like ifunc
 372    resolvers and early static TLS init.  */
 373 #ifdef HAVE_CC_NO_STACK_PROTECTOR
 374 # define inhibit_stack_protector \
 375     __attribute__ ((__optimize__ ("-fno-stack-protector")))
 376 #else
 377 # define inhibit_stack_protector
 378 #endif
 379
 380 /* The following macros are used for PLT bypassing within libc.so
 381    (and if needed other libraries similarly).
 382    First of all, you need to have the function prototyped somewhere,
 383    say in foo/foo.h:
 384
 385    int foo (int __bar);
 386
 387    If calls to foo within libc.so should always go to foo defined in libc.so,
 388    then in include/foo.h you add:
 389
 390    libc_hidden_proto (foo)
 391
 392    line and after the foo function definition:
 393
 394    int foo (int __bar)
 395    {
 396      return __bar;
 397    }
 398    libc_hidden_def (foo)
 399
 400    or
 401
 402    int foo (int __bar)
 403    {
 404      return __bar;
 405    }
 406    libc_hidden_weak (foo)
 407
 408    Similarly for global data.  If references to foo within libc.so should
 409    always go to foo defined in libc.so, then in include/foo.h you add:
 410
 411    libc_hidden_proto (foo)
 412
 413    line and after foo's definition:
 414
 415    int foo = INITIAL_FOO_VALUE;
 416    libc_hidden_data_def (foo)
 417
 418    or
 419
 420    int foo = INITIAL_FOO_VALUE;
 421    libc_hidden_data_weak (foo)
 422
 423    If foo is normally just an alias (strong or weak) to some other function,
 424    you should use the normal strong_alias first, then add libc_hidden_def
 425    or libc_hidden_weak:
 426
 427    int baz (int __bar)
 428    {
 429      return __bar;
 430    }
 431    strong_alias (baz, foo)
 432    libc_hidden_weak (foo)
 433
 434    If the function should be internal to multiple objects, say ld.so and
 435    libc.so, the best way is to use:
 436
 437    #if IS_IN (libc) || IS_IN (rtld)
 438    hidden_proto (foo)
 439    #endif
 440
 441    in include/foo.h and the normal macros at all function definitions
 442    depending on what DSO they belong to.
 443
 444    If versioned_symbol macro is used to define foo,
 445    libc_hidden_ver macro should be used, as in:
 446
 447    int __real_foo (int __bar)
 448    {
 449      return __bar;
 450    }
 451    versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
 452    libc_hidden_ver (__real_foo, foo)  */
 453
 454 #if defined SHARED && !defined NO_HIDDEN
 455 # ifndef __ASSEMBLER__
 456 #  define __hidden_proto_hiddenattr(attrs...) \
 457   __attribute__ ((visibility ("hidden"), ##attrs))
 458 #  define hidden_proto(name, attrs...) \
 459   __hidden_proto (name, , __GI_##name, ##attrs)
 460 #  define hidden_tls_proto(name, attrs...) \
 461   __hidden_proto (name, __thread, __GI_##name, ##attrs)
 462 #  define __hidden_proto(name, thread, internal, attrs...)           \
 463   extern thread __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
 464   __hidden_proto_hiddenattr (attrs);
 465 #  define __hidden_asmname(name) \
 466   __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
 467 #  define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
 468 #  define __hidden_asmname2(prefix, name) #prefix name
 469 #  define __hidden_ver1(local, internal, name) \
 470   extern __typeof (name) __EI_##name __asm__(__hidden_asmname (#internal)); \
 471   extern __typeof (name) __EI_##name \
 472         __attribute__((alias (__hidden_asmname (#local))))
 473 #  define hidden_ver(local, name)       __hidden_ver1(local, __GI_##name, name);
 474 #  define hidden_data_ver(local, name)  hidden_ver(local, name)
 475 #  define hidden_def(name)              __hidden_ver1(__GI_##name, name, name);
 476 #  define hidden_data_def(name)         hidden_def(name)
 477 #  define hidden_weak(name) \
 478         __hidden_ver1(__GI_##name, name, name) __attribute__((weak));
 479 #  define hidden_data_weak(name)        hidden_weak(name)
 480 #  define hidden_nolink(name, lib, version) \
 481   __hidden_nolink1 (__GI_##name, __EI_##name, name, VERSION_##lib##_##version)
 482 #  define __hidden_nolink1(local, internal, name, version) \
 483   __hidden_nolink2 (local, internal, name, version)
 484 #  define __hidden_nolink2(local, internal, name, version) \
 485   extern __typeof (name) internal __attribute__ ((alias (#local))); \
 486   __hidden_nolink3 (local, internal, #name "@" #version)
 487 #  define __hidden_nolink3(local, internal, vername) \
 488   __asm__ (".symver " #internal ", " vername);
 489 # else
 490 /* For assembly, we need to do the opposite of what we do in C:
 491    in assembly gcc __REDIRECT stuff is not in place, so functions
 492    are defined by its normal name and we need to create the
 493    __GI_* alias to it, in C __REDIRECT causes the function definition
 494    to use __GI_* name and we need to add alias to the real name.
 495    There is no reason to use hidden_weak over hidden_def in assembly,
 496    but we provide it for consistency with the C usage.
 497    hidden_proto doesn't make sense for assembly but the equivalent
 498    is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET.  */
 499 #  define hidden_def(name)      strong_alias (name, __GI_##name)
 500 #  define hidden_weak(name)     hidden_def (name)
 501 #  define hidden_ver(local, name) strong_alias (local, __GI_##name)
 502 #  define hidden_data_def(name) strong_data_alias (name, __GI_##name)
 503 #  define hidden_data_weak(name)        hidden_data_def (name)
 504 #  define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
 505 #  define HIDDEN_JUMPTARGET(name) __GI_##name
 506 # endif
 507 #else
 508 # ifndef __ASSEMBLER__
 509 #  if !defined SHARED && IS_IN (libc) && !defined LIBC_NONSHARED \
 510       && !defined NO_HIDDEN
 511 #   define __hidden_proto_hiddenattr(attrs...) \
 512   __attribute__ ((visibility ("hidden"), ##attrs))
 513 #   define hidden_proto(name, attrs...) \
 514   __hidden_proto (name, , name, ##attrs)
 515 #   define hidden_tls_proto(name, attrs...) \
 516   __hidden_proto (name, __thread, name, ##attrs)
 517 #  define __hidden_proto(name, thread, internal, attrs...)           \
 518   extern thread __typeof (name) name __hidden_proto_hiddenattr (attrs);
 519 # else
 520 #   define hidden_proto(name, attrs...)
 521 #   define hidden_tls_proto(name, attrs...)
 522 # endif
 523 # else
 524 #  define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
 525 # endif /* Not  __ASSEMBLER__ */
 526 # define hidden_weak(name)
 527 # define hidden_def(name)
 528 # define hidden_ver(local, name)
 529 # define hidden_data_weak(name)
 530 # define hidden_data_def(name)
 531 # define hidden_data_ver(local, name)
 532 # define hidden_nolink(name, lib, version)
 533 #endif
 534
 535 #if IS_IN (libc)
 536 # define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 537 # define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 538 # define libc_hidden_def(name) hidden_def (name)
 539 # define libc_hidden_weak(name) hidden_weak (name)
 540 # ifdef LINK_OBSOLETE_RPC
 541    /* libc_hidden_nolink_sunrpc should only get used in sunrpc code.  */
 542 #  define libc_hidden_nolink_sunrpc(name, version) hidden_def (name)
 543 # else
 544 #  define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
 545 # endif
 546 # define libc_hidden_ver(local, name) hidden_ver (local, name)
 547 # define libc_hidden_data_def(name) hidden_data_def (name)
 548 # define libc_hidden_data_weak(name) hidden_data_weak (name)
 549 # define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
 550 #else
 551 # define libc_hidden_proto(name, attrs...)
 552 # define libc_hidden_tls_proto(name, attrs...)
 553 # define libc_hidden_def(name)
 554 # define libc_hidden_weak(name)
 555 # define libc_hidden_ver(local, name)
 556 # define libc_hidden_data_def(name)
 557 # define libc_hidden_data_weak(name)
 558 # define libc_hidden_data_ver(local, name)
 559 #endif
 560
 561 #if IS_IN (rtld)
 562 # define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 563 # define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 564 # define rtld_hidden_def(name) hidden_def (name)
 565 # define rtld_hidden_weak(name) hidden_weak (name)
 566 # define rtld_hidden_ver(local, name) hidden_ver (local, name)
 567 # define rtld_hidden_data_def(name) hidden_data_def (name)
 568 # define rtld_hidden_data_weak(name) hidden_data_weak (name)
 569 # define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
 570 #else
 571 # define rtld_hidden_proto(name, attrs...)
 572 # define rtld_hidden_tls_proto(name, attrs...)
 573 # define rtld_hidden_def(name)
 574 # define rtld_hidden_weak(name)
 575 # define rtld_hidden_ver(local, name)
 576 # define rtld_hidden_data_def(name)
 577 # define rtld_hidden_data_weak(name)
 578 # define rtld_hidden_data_ver(local, name)
 579 #endif
 580
 581 #if IS_IN (libm)
 582 # define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 583 # define libm_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 584 # define libm_hidden_def(name) hidden_def (name)
 585 # define libm_hidden_weak(name) hidden_weak (name)
 586 # define libm_hidden_ver(local, name) hidden_ver (local, name)
 587 # define libm_hidden_data_def(name) hidden_data_def (name)
 588 # define libm_hidden_data_weak(name) hidden_data_weak (name)
 589 # define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
 590 #else
 591 # define libm_hidden_proto(name, attrs...)
 592 # define libm_hidden_tls_proto(name, attrs...)
 593 # define libm_hidden_def(name)
 594 # define libm_hidden_weak(name)
 595 # define libm_hidden_ver(local, name)
 596 # define libm_hidden_data_def(name)
 597 # define libm_hidden_data_weak(name)
 598 # define libm_hidden_data_ver(local, name)
 599 #endif
 600
 601 #if IS_IN (libmvec)
 602 # define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 603 # define libmvec_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 604 # define libmvec_hidden_def(name) hidden_def (name)
 605 # define libmvec_hidden_weak(name) hidden_weak (name)
 606 # define libmvec_hidden_ver(local, name) hidden_ver (local, name)
 607 # define libmvec_hidden_data_def(name) hidden_data_def (name)
 608 # define libmvec_hidden_data_weak(name) hidden_data_weak (name)
 609 # define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
 610 #else
 611 # define libmvec_hidden_proto(name, attrs...)
 612 # define libmvec_hidden_tls_proto(name, attrs...)
 613 # define libmvec_hidden_def(name)
 614 # define libmvec_hidden_weak(name)
 615 # define libmvec_hidden_ver(local, name)
 616 # define libmvec_hidden_data_def(name)
 617 # define libmvec_hidden_data_weak(name)
 618 # define libmvec_hidden_data_ver(local, name)
 619 #endif
 620
 621 #if IS_IN (libresolv)
 622 # define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 623 # define libresolv_hidden_tls_proto(name, attrs...) \
 624   hidden_tls_proto (name, ##attrs)
 625 # define libresolv_hidden_def(name) hidden_def (name)
 626 # define libresolv_hidden_weak(name) hidden_weak (name)
 627 # define libresolv_hidden_ver(local, name) hidden_ver (local, name)
 628 # define libresolv_hidden_data_def(name) hidden_data_def (name)
 629 # define libresolv_hidden_data_weak(name) hidden_data_weak (name)
 630 # define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
 631 #else
 632 # define libresolv_hidden_proto(name, attrs...)
 633 # define libresolv_hidden_tls_proto(name, attrs...)
 634 # define libresolv_hidden_def(name)
 635 # define libresolv_hidden_weak(name)
 636 # define libresolv_hidden_ver(local, name)
 637 # define libresolv_hidden_data_def(name)
 638 # define libresolv_hidden_data_weak(name)
 639 # define libresolv_hidden_data_ver(local, name)
 640 #endif
 641
 642 #if IS_IN (librt)
 643 # define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 644 # define librt_hidden_tls_proto(name, attrs...) \
 645   hidden_tls_proto (name, ##attrs)
 646 # define librt_hidden_def(name) hidden_def (name)
 647 # define librt_hidden_weak(name) hidden_weak (name)
 648 # define librt_hidden_ver(local, name) hidden_ver (local, name)
 649 # define librt_hidden_data_def(name) hidden_data_def (name)
 650 # define librt_hidden_data_weak(name) hidden_data_weak (name)
 651 # define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
 652 #else
 653 # define librt_hidden_proto(name, attrs...)
 654 # define librt_hidden_tls_proto(name, attrs...)
 655 # define librt_hidden_def(name)
 656 # define librt_hidden_weak(name)
 657 # define librt_hidden_ver(local, name)
 658 # define librt_hidden_data_def(name)
 659 # define librt_hidden_data_weak(name)
 660 # define librt_hidden_data_ver(local, name)
 661 #endif
 662
 663 #if IS_IN (libdl)
 664 # define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 665 # define libdl_hidden_tls_proto(name, attrs...) \
 666   hidden_tls_proto (name, ##attrs)
 667 # define libdl_hidden_def(name) hidden_def (name)
 668 # define libdl_hidden_weak(name) hidden_weak (name)
 669 # define libdl_hidden_ver(local, name) hidden_ver (local, name)
 670 # define libdl_hidden_data_def(name) hidden_data_def (name)
 671 # define libdl_hidden_data_weak(name) hidden_data_weak (name)
 672 # define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
 673 #else
 674 # define libdl_hidden_proto(name, attrs...)
 675 # define libdl_hidden_tls_proto(name, attrs...)
 676 # define libdl_hidden_def(name)
 677 # define libdl_hidden_weak(name)
 678 # define libdl_hidden_ver(local, name)
 679 # define libdl_hidden_data_def(name)
 680 # define libdl_hidden_data_weak(name)
 681 # define libdl_hidden_data_ver(local, name)
 682 #endif
 683
 684 #if IS_IN (libnss_files)
 685 # define libnss_files_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 686 # define libnss_files_hidden_tls_proto(name, attrs...) \
 687   hidden_tls_proto (name, ##attrs)
 688 # define libnss_files_hidden_def(name) hidden_def (name)
 689 # define libnss_files_hidden_weak(name) hidden_weak (name)
 690 # define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
 691 # define libnss_files_hidden_data_def(name) hidden_data_def (name)
 692 # define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
 693 # define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
 694 #else
 695 # define libnss_files_hidden_proto(name, attrs...)
 696 # define libnss_files_hidden_tls_proto(name, attrs...)
 697 # define libnss_files_hidden_def(name)
 698 # define libnss_files_hidden_weak(name)
 699 # define libnss_files_hidden_ver(local, name)
 700 # define libnss_files_hidden_data_def(name)
 701 # define libnss_files_hidden_data_weak(name)
 702 # define libnss_files_hidden_data_ver(local, name)
 703 #endif
 704
 705 #if IS_IN (libnsl)
 706 # define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 707 # define libnsl_hidden_tls_proto(name, attrs...) \
 708   hidden_tls_proto (name, ##attrs)
 709 # ifdef LINK_OBSOLETE_NSL
 710    /* libnsl_hidden_nolink should only get used in libnsl code.  */
 711 #  define libnsl_hidden_nolink_def(name, version) libnsl_hidden_def (name)
 712 # else
 713 #  define libnsl_hidden_nolink_def(name, version) hidden_nolink (name, libnsl, version)
 714 # endif
 715 # define libnsl_hidden_def(name) hidden_def (name)
 716 # define libnsl_hidden_weak(name) hidden_weak (name)
 717 # define libnsl_hidden_ver(local, name) hidden_ver (local, name)
 718 # define libnsl_hidden_data_def(name) hidden_data_def (name)
 719 # define libnsl_hidden_data_weak(name) hidden_data_weak (name)
 720 # define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
 721 #else
 722 # define libnsl_hidden_proto(name, attrs...)
 723 # define libnsl_hidden_tls_proto(name, attrs...)
 724 # define libnsl_hidden_def(name)
 725 # define libnsl_hidden_weak(name)
 726 # define libnsl_hidden_ver(local, name)
 727 # define libnsl_hidden_data_def(name)
 728 # define libnsl_hidden_data_weak(name)
 729 # define libnsl_hidden_data_ver(local, name)
 730 #endif
 731
 732 #if IS_IN (libnss_nisplus)
 733 # define libnss_nisplus_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 734 # define libnss_nisplus_hidden_tls_proto(name, attrs...) \
 735   hidden_tls_proto (name, ##attrs)
 736 # define libnss_nisplus_hidden_def(name) hidden_def (name)
 737 # define libnss_nisplus_hidden_weak(name) hidden_weak (name)
 738 # define libnss_nisplus_hidden_ver(local, name) hidden_ver (local, name)
 739 # define libnss_nisplus_hidden_data_def(name) hidden_data_def (name)
 740 # define libnss_nisplus_hidden_data_weak(name) hidden_data_weak (name)
 741 # define libnss_nisplus_hidden_data_ver(local, name) hidden_data_ver (local, name)
 742 #else
 743 # define libnss_nisplus_hidden_proto(name, attrs...)
 744 # define libnss_nisplus_hidden_tls_proto(name, attrs...)
 745 # define libnss_nisplus_hidden_def(name)
 746 # define libnss_nisplus_hidden_weak(name)
 747 # define libnss_nisplus_hidden_ver(local, name)
 748 # define libnss_nisplus_hidden_data_def(name)
 749 # define libnss_nisplus_hidden_data_weak(name)
 750 # define libnss_nisplus_hidden_data_ver(local, name)
 751 #endif
 752
 753 #define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
 754 #define libc_hidden_builtin_def(name) libc_hidden_def (name)
 755 #define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
 756 #define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
 757 #ifdef __ASSEMBLER__
 758 # define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
 759 #endif
 760
 761 #if IS_IN (libutil)
 762 # define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 763 # define libutil_hidden_tls_proto(name, attrs...) \
 764   hidden_tls_proto (name, ##attrs)
 765 # define libutil_hidden_def(name) hidden_def (name)
 766 # define libutil_hidden_weak(name) hidden_weak (name)
 767 # define libutil_hidden_ver(local, name) hidden_ver (local, name)
 768 # define libutil_hidden_data_def(name) hidden_data_def (name)
 769 # define libutil_hidden_data_weak(name) hidden_data_weak (name)
 770 # define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
 771 #else
 772 # define libutil_hidden_proto(name, attrs...)
 773 # define libutil_hidden_tls_proto(name, attrs...)
 774 # define libutil_hidden_def(name)
 775 # define libutil_hidden_weak(name)
 776 # define libutil_hidden_ver(local, name)
 777 # define libutil_hidden_data_def(name)
 778 # define libutil_hidden_data_weak(name)
 779 # define libutil_hidden_data_ver(local, name)
 780 #endif
 781
 782 /* Get some dirty hacks.  */
 783 #include <symbol-hacks.h>
 784
 785 /* Move compatibility symbols out of the way by placing them all in a
 786    special section.  */
 787 #ifndef __ASSEMBLER__
 788 # define attribute_compat_text_section \
 789     __attribute__ ((section (".text.compat")))
 790 # define attribute_compat_data_section \
 791     __attribute__ ((section (".data.compat")))
 792 #else
 793 # define compat_text_section .section ".text.compat", "ax";
 794 # define compat_data_section .section ".data.compat", "aw";
 795 #endif
 796
 797 /* Helper / base  macros for indirect function symbols.  */
 798 #define __ifunc_resolver(type_name, name, expr, arg, init, classifier)  \
 799   classifier inhibit_stack_protector                                    \
 800   __typeof (type_name) *name##_ifunc (arg)                              \
 801   {                                                                     \
 802     init ();                                                            \
 803     __typeof (type_name) *res = expr;                                   \
 804     return res;                                                         \
 805   }
 806
 807 #ifdef HAVE_GCC_IFUNC
 808 # define __ifunc(type_name, name, expr, arg, init)                      \
 809   extern __typeof (type_name) name __attribute__                        \
 810                               ((ifunc (#name "_ifunc")));               \
 811   __ifunc_resolver (type_name, name, expr, arg, init, static)
 812
 813 # define __ifunc_hidden(type_name, name, expr, arg, init)       \
 814   __ifunc (type_name, name, expr, arg, init)
 815 #else
 816 /* Gcc does not support __attribute__ ((ifunc (...))).  Use the old behaviour
 817    as fallback.  But keep in mind that the debug information for the ifunc
 818    resolver functions is not correct.  It contains the ifunc'ed function as
 819    DW_AT_linkage_name.  E.g. lldb uses this field and an inferior function
 820    call of the ifunc'ed function will fail due to "no matching function for
 821    call to ..." because the ifunc'ed function and the resolver function have
 822    different signatures.  (Gcc support is disabled at least on a ppc64le
 823    Ubuntu 14.04 system.)  */
 824
 825 # define __ifunc(type_name, name, expr, arg, init)                      \
 826   extern __typeof (type_name) name;                                     \
 827   __typeof (type_name) *name##_ifunc (arg) __asm__ (#name);             \
 828   __ifunc_resolver (type_name, name, expr, arg, init,)                  \
 829  __asm__ (".type " #name ", %gnu_indirect_function");
 830
 831 # define __ifunc_hidden(type_name, name, expr, arg, init)               \
 832   extern __typeof (type_name) __libc_##name;                            \
 833   __ifunc (type_name, __libc_##name, expr, arg, init)                   \
 834   strong_alias (__libc_##name, name);
 835 #endif /* !HAVE_GCC_IFUNC  */
 836
 837 /* The following macros are used for indirect function symbols in libc.so.
 838    First of all, you need to have the function prototyped somewhere,
 839    say in foo.h:
 840
 841    int foo (int __bar);
 842
 843    If you have an implementation for foo which e.g. uses a special hardware
 844    feature which isn't available on all machines where this libc.so will be
 845    used but decideable if available at runtime e.g. via hwcaps, you can provide
 846    two or multiple implementations of foo:
 847
 848    int __foo_default (int __bar)
 849    {
 850      return __bar;
 851    }
 852
 853    int __foo_special (int __bar)
 854    {
 855      return __bar;
 856    }
 857
 858    If your function foo has no libc_hidden_proto (foo) defined for PLT
 859    bypassing, you can use:
 860
 861    #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
 862
 863    libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
 864
 865    This will define a resolver function for foo which returns __foo_special or
 866    __foo_default depending on your specified expression.  Please note that you
 867    have to define a macro function INIT_ARCH before using libc_ifunc macro as
 868    it is called by the resolver function before evaluating the specified
 869    expression.  In this example it is used to prepare the hwcap variable.
 870    The resolver function is assigned to an ifunc'ed symbol foo.  Calls to foo
 871    from inside or outside of libc.so will be indirected by a PLT call.
 872
 873    If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
 874    and calls to foo within libc.so should always go to one specific
 875    implementation of foo e.g. __foo_default then you have to add:
 876
 877    __hidden_ver1 (__foo_default, __GI_foo, __foo_default);
 878
 879    or a tweaked definition of libc_hidden_def macro after the __foo_default
 880    function definition.  Calls to foo within libc.so will always go directly to
 881    __foo_default.  Calls to foo from outside libc.so will be indirected by a
 882    PLT call to ifunc'ed symbol foo which you have to define in a separate
 883    compile unit:
 884
 885    #define foo __redirect_foo
 886    #include <foo.h>
 887    #undef foo
 888
 889    extern __typeof (__redirect_foo) __foo_default attribute_hidden;
 890    extern __typeof (__redirect_foo) __foo_special attribute_hidden;
 891
 892    libc_ifunc_redirected (__redirect_foo, foo,
 893                           (hwcap & HWCAP_SPECIAL)
 894                           ? __foo_special
 895                           : __foo_default);
 896
 897    This will define the ifunc'ed symbol foo like above.  The redirection of foo
 898    in header file is needed to omit an additional defintion of __GI_foo which
 899    would end in a linker error while linking libc.so.  You have to specify
 900    __redirect_foo as first parameter which is used within libc_ifunc_redirected
 901    macro in conjunction with typeof to define the ifunc'ed symbol foo.
 902
 903    If your function foo has a libc_hidden_proto (foo) defined and calls to foo
 904    within or from outside libc.so should go via ifunc'ed symbol, then you have
 905    to use:
 906
 907    libc_ifunc_hidden (foo, foo,
 908                       (hwcap & HWCAP_SPECIAL)
 909                       ? __foo_special
 910                       : __foo_default);
 911    libc_hidden_def (foo)
 912
 913    The first parameter foo of libc_ifunc_hidden macro is used in the same way
 914    as for libc_ifunc_redirected macro.  */
 915
 916 #define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
 917
 918 #define libc_ifunc_redirected(redirected_name, name, expr)      \
 919   __ifunc (redirected_name, name, expr, void, INIT_ARCH)
 920
 921 #define libc_ifunc_hidden(redirected_name, name, expr)                  \
 922   __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
 923
 924 /* The body of the function is supposed to use __get_cpu_features
 925    which will, if necessary, initialize the data first.  */
 926 #define libm_ifunc_init()
 927 #define libm_ifunc(name, expr)                          \
 928   __ifunc (name, name, expr, void, libm_ifunc_init)
 929
 930 /* Add the compiler optimization to inhibit loop transformation to library
 931    calls.  This is used to avoid recursive calls in memset and memmove
 932    default implementations.  */
 933 #ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
 934 # define inhibit_loop_to_libcall \
 935     __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
 936 #else
 937 # define inhibit_loop_to_libcall
 938 #endif
 939 \f
 940 /* These macros facilitate sharing source files with gnulib.
 941
 942    They are here instead of sys/cdefs.h because they should not be
 943    used in public header files.
 944
 945    Their definitions should be kept consistent with the definitions in
 946    gnulib-common.m4, but it is not necessary to cater to old non-GCC
 947    compilers, since they will only be used while building glibc itself.
 948    (Note that _GNUC_PREREQ cannot be used in this file.)  */
 949
 950 /* Define as a marker that can be attached to declarations that might not
 951     be used.  This helps to reduce warnings, such as from
 952     GCC -Wunused-parameter.  */
 953 #if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
 954 # define _GL_UNUSED __attribute__ ((__unused__))
 955 #else
 956 # define _GL_UNUSED
 957 #endif
 958
 959 /* gcc supports the "unused" attribute on possibly unused labels, and
 960    g++ has since version 4.5.  Note to support C++ as well as C,
 961    _GL_UNUSED_LABEL should be used with a trailing ;  */
 962 #if !defined __cplusplus || __GNUC__ > 4 \
 963     || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
 964 # define _GL_UNUSED_LABEL _GL_UNUSED
 965 #else
 966 # define _GL_UNUSED_LABEL
 967 #endif
 968
 969 /* The __pure__ attribute was added in gcc 2.96.  */
 970 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
 971 # define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
 972 #else
 973 # define _GL_ATTRIBUTE_PURE /* empty */
 974 #endif
 975
 976 /* The __const__ attribute was added in gcc 2.95.  */
 977 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
 978 # define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
 979 #else
 980 # define _GL_ATTRIBUTE_CONST /* empty */
 981 #endif
 982
 983 #endif /* !_ISOMAC */
 984 #endif /* libc-symbols.h */