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) 1995-2018 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef _LIBC_SYMBOLS_H
  21 #define _LIBC_SYMBOLS_H 1
  22
  23 /* This file is included implicitly in the compilation of every source file,
  24    using -include.  It includes config.h.  */
  25
  26 /* Enable declarations of GNU extensions, since we are compiling them.  */
  27 #define _GNU_SOURCE 1
  28
  29 #ifdef MODULE_NAME
  30
  31 /* Use `#if IS_IN (module)` to detect what component is being compiled.  */
  32 #define PASTE_NAME1(a,b) a##b
  33 #define PASTE_NAME(a,b)  PASTE_NAME1 (a,b)
  34 #define IN_MODULE        PASTE_NAME (MODULE_, MODULE_NAME)
  35 #define IS_IN(lib)       (IN_MODULE == MODULE_##lib)
  36
  37 /* True if the current module is a versioned library.  Versioned
  38    library names culled from shlib-versions files are assigned a
  39    MODULE_* value greater than MODULE_LIBS_BEGIN.  */
  40 #define IS_IN_LIB        (IN_MODULE > MODULE_LIBS_BEGIN)
  41
  42 /* The testsuite, and some other ancillary code, should be compiled against
  43    as close an approximation to the installed headers as possible.
  44    Defining this symbol disables most internal-use-only declarations
  45    provided by this header, and all those provided by other internal
  46    wrapper headers.  */
  47 #if IS_IN (testsuite) || defined IS_IN_build || defined __cplusplus
  48 # define _ISOMAC 1
  49 #endif
  50
  51 #else
  52 /* The generation process for a few files created very early in the
  53    build (notably libc-modules.h itself) involves preprocessing this
  54    header without defining MODULE_NAME.  Under these conditions,
  55    internal declarations (especially from config.h) must be visible,
  56    but IS_IN should always evaluate as false.  */
  57 # define IS_IN(lib) 0
  58 # define IS_IN_LIB 0
  59 # define IN_MODULE (-1)
  60 #endif
  61
  62 #ifndef _ISOMAC
  63
  64 /* This is defined for the compilation of all C library code.  features.h
  65    tests this to avoid inclusion of stubs.h while compiling the library,
  66    before stubs.h has been generated.  Some library code that is shared
  67    with other packages also tests this symbol to see if it is being
  68    compiled as part of the C library.  We must define this before including
  69    config.h, because it makes some definitions conditional on whether libc
  70    itself is being compiled, or just some generator program.  */
  71 #define _LIBC   1
  72
  73 /* Some files must be compiled with optimization on.  */
  74 #if !defined __ASSEMBLER__ && !defined __OPTIMIZE__
  75 # error "glibc cannot be compiled without optimization"
  76 #endif
  77
  78 /* -ffast-math cannot be applied to the C library, as it alters the ABI.
  79    Some test components that use -ffast-math are currently not part of
  80    IS_IN (testsuite) for technical reasons, so we have a secondary override.  */
  81 #if defined __FAST_MATH__ && !defined TEST_FAST_MATH
  82 # error "glibc must not be compiled with -ffast-math"
  83 #endif
  84
  85 #include <config.h>
  86
  87 /* When PIC is defined and SHARED isn't defined, we are building PIE
  88    by default.  */
  89 #if defined PIC && !defined SHARED
  90 # define BUILD_PIE_DEFAULT 1
  91 #else
  92 # define BUILD_PIE_DEFAULT 0
  93 #endif
  94
  95 /* Define this for the benefit of portable GNU code that wants to check it.
  96    Code that checks with #if will not #include <config.h> again, since we've
  97    already done it (and this file is implicitly included in every compile,
  98    via -include).  Code that checks with #ifdef will #include <config.h>,
  99    but that file should always be idempotent (i.e., it's just #define/#undef
 100    and nothing else anywhere should be changing the macro state it touches),
 101    so it's harmless.  */
 102 #define HAVE_CONFIG_H   0
 103
 104 /* Define these macros for the benefit of portable GNU code that wants to check
 105    them.  Of course, STDC_HEADERS is never false when building libc!  */
 106 #define STDC_HEADERS    1
 107 #define HAVE_MBSTATE_T  1
 108 #define HAVE_MBSRTOWCS  1
 109 #define HAVE_LIBINTL_H  1
 110 #define HAVE_WCTYPE_H   1
 111 #define HAVE_ISWCTYPE   1
 112 #define ENABLE_NLS      1
 113
 114 /* The symbols in all the user (non-_) macros are C symbols.  */
 115
 116 #ifndef __SYMBOL_PREFIX
 117 # define __SYMBOL_PREFIX
 118 #endif
 119
 120 #ifndef C_SYMBOL_NAME
 121 # define C_SYMBOL_NAME(name) name
 122 #endif
 123
 124 #ifndef ASM_LINE_SEP
 125 # define ASM_LINE_SEP ;
 126 #endif
 127
 128 #ifndef __ASSEMBLER__
 129 /* GCC understands weak symbols and aliases; use its interface where
 130    possible, instead of embedded assembly language.  */
 131
 132 /* Define ALIASNAME as a strong alias for NAME.  */
 133 # define strong_alias(name, aliasname) _strong_alias(name, aliasname)
 134 # define _strong_alias(name, aliasname) \
 135   extern __typeof (name) aliasname __attribute__ ((alias (#name)));
 136
 137 /* This comes between the return type and function name in
 138    a function definition to make that definition weak.  */
 139 # define weak_function __attribute__ ((weak))
 140 # define weak_const_function __attribute__ ((weak, __const__))
 141
 142 /* Define ALIASNAME as a weak alias for NAME.
 143    If weak aliases are not available, this defines a strong alias.  */
 144 # define weak_alias(name, aliasname) _weak_alias (name, aliasname)
 145 # define _weak_alias(name, aliasname) \
 146   extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
 147
 148 /* Same as WEAK_ALIAS, but mark symbol as hidden.  */
 149 # define weak_hidden_alias(name, aliasname) \
 150   _weak_hidden_alias (name, aliasname)
 151 # define _weak_hidden_alias(name, aliasname) \
 152   extern __typeof (name) aliasname \
 153     __attribute__ ((weak, alias (#name), __visibility__ ("hidden")));
 154
 155 /* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined).  */
 156 # define weak_extern(symbol) _weak_extern (weak symbol)
 157 # define _weak_extern(expr) _Pragma (#expr)
 158
 159 /* In shared builds, the expression call_function_static_weak
 160    (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
 161    identifier) unconditionally, with the (potentially empty) argument
 162    list ARGUMENTS.  In static builds, if FUNCTION-SYMBOL has a
 163    definition, the function is invoked as before; if FUNCTION-SYMBOL
 164    is NULL, no call is performed.  */
 165 # ifdef SHARED
 166 #  define call_function_static_weak(func, ...) func (__VA_ARGS__)
 167 # else  /* !SHARED */
 168 #  define call_function_static_weak(func, ...)          \
 169   ({                                                    \
 170     extern __typeof__ (func) func weak_function;        \
 171     (func != NULL ? func (__VA_ARGS__) : (void)0);      \
 172   })
 173 # endif
 174
 175 #else /* __ASSEMBLER__ */
 176
 177 # ifdef HAVE_ASM_SET_DIRECTIVE
 178 #  define strong_alias(original, alias)                         \
 179   .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP             \
 180   .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
 181 #  define strong_data_alias(original, alias) strong_alias(original, alias)
 182 # else
 183 #  define strong_alias(original, alias)                         \
 184   .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP             \
 185   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 186 #  define strong_data_alias(original, alias) strong_alias(original, alias)
 187 # endif
 188
 189 # define weak_alias(original, alias)                                    \
 190   .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP                              \
 191   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 192
 193 # define weak_extern(symbol)                                            \
 194   .weak C_SYMBOL_NAME (symbol)
 195
 196 #endif /* __ASSEMBLER__ */
 197
 198 /* Determine the return address.  */
 199 #define RETURN_ADDRESS(nr) \
 200   __builtin_extract_return_addr (__builtin_return_address (nr))
 201
 202 /* When a reference to SYMBOL is encountered, the linker will emit a
 203    warning message MSG.  */
 204 /* We want the .gnu.warning.SYMBOL section to be unallocated.  */
 205 #define __make_section_unallocated(section_string)      \
 206   asm (".section " section_string "\n\t.previous");
 207
 208 /* Tacking on "\n\t#" to the section name makes gcc put it's bogus
 209    section attributes on what looks like a comment to the assembler.  */
 210 #ifdef HAVE_SECTION_QUOTES
 211 # define __sec_comment "\"\n\t#\""
 212 #else
 213 # define __sec_comment "\n\t#"
 214 #endif
 215 #define link_warning(symbol, msg) \
 216   __make_section_unallocated (".gnu.warning." #symbol) \
 217   static const char __evoke_link_warning_##symbol[]     \
 218     __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
 219     = msg;
 220 #define libc_freeres_ptr(decl) \
 221   __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
 222   decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
 223 #define __libc_freeres_fn_section \
 224   __attribute__ ((section ("__libc_freeres_fn")))
 225
 226 #define libc_freeres_fn(name)   \
 227   static void name (void) __attribute_used__ __libc_freeres_fn_section; \
 228   text_set_element (__libc_subfreeres, name);                           \
 229   static void name (void)
 230
 231 /* A canned warning for sysdeps/stub functions.  */
 232 #define stub_warning(name) \
 233   __make_section_unallocated (".gnu.glibc-stub." #name) \
 234   link_warning (name, #name " is not implemented and will always fail")
 235
 236 /* Warning for linking functions calling dlopen into static binaries.  */
 237 #ifdef SHARED
 238 #define static_link_warning(name)
 239 #else
 240 #define static_link_warning(name) static_link_warning1(name)
 241 #define static_link_warning1(name) \
 242   link_warning(name, "Using '" #name "' in statically linked applications \
 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 PIC || !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE) \
 511       && !defined NO_HIDDEN
 512 #   define __hidden_proto_hiddenattr(attrs...) \
 513   __attribute__ ((visibility ("hidden"), ##attrs))
 514 #   define hidden_proto(name, attrs...) \
 515   __hidden_proto (name, , name, ##attrs)
 516 #   define hidden_tls_proto(name, attrs...) \
 517   __hidden_proto (name, __thread, name, ##attrs)
 518 #  define __hidden_proto(name, thread, internal, attrs...)           \
 519   extern thread __typeof (name) name __hidden_proto_hiddenattr (attrs);
 520 # else
 521 #   define hidden_proto(name, attrs...)
 522 #   define hidden_tls_proto(name, attrs...)
 523 # endif
 524 # else
 525 #  define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
 526 # endif /* Not  __ASSEMBLER__ */
 527 # define hidden_weak(name)
 528 # define hidden_def(name)
 529 # define hidden_ver(local, name)
 530 # define hidden_data_weak(name)
 531 # define hidden_data_def(name)
 532 # define hidden_data_ver(local, name)
 533 # define hidden_nolink(name, lib, version)
 534 #endif
 535
 536 #if IS_IN (libc)
 537 # define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 538 # define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 539 # define libc_hidden_def(name) hidden_def (name)
 540 # define libc_hidden_weak(name) hidden_weak (name)
 541 # ifdef LINK_OBSOLETE_RPC
 542    /* libc_hidden_nolink_sunrpc should only get used in sunrpc code.  */
 543 #  define libc_hidden_nolink_sunrpc(name, version) hidden_def (name)
 544 # else
 545 #  define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
 546 # endif
 547 # define libc_hidden_ver(local, name) hidden_ver (local, name)
 548 # define libc_hidden_data_def(name) hidden_data_def (name)
 549 # define libc_hidden_data_weak(name) hidden_data_weak (name)
 550 # define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
 551 #else
 552 # define libc_hidden_proto(name, attrs...)
 553 # define libc_hidden_tls_proto(name, attrs...)
 554 # define libc_hidden_def(name)
 555 # define libc_hidden_weak(name)
 556 # define libc_hidden_ver(local, name)
 557 # define libc_hidden_data_def(name)
 558 # define libc_hidden_data_weak(name)
 559 # define libc_hidden_data_ver(local, name)
 560 #endif
 561
 562 #if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
 563 # define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 564 # define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 565 # define rtld_hidden_def(name) hidden_def (name)
 566 # define rtld_hidden_weak(name) hidden_weak (name)
 567 # define rtld_hidden_ver(local, name) hidden_ver (local, name)
 568 # define rtld_hidden_data_def(name) hidden_data_def (name)
 569 # define rtld_hidden_data_weak(name) hidden_data_weak (name)
 570 # define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
 571 #else
 572 # define rtld_hidden_proto(name, attrs...)
 573 # define rtld_hidden_tls_proto(name, attrs...)
 574 # define rtld_hidden_def(name)
 575 # define rtld_hidden_weak(name)
 576 # define rtld_hidden_ver(local, name)
 577 # define rtld_hidden_data_def(name)
 578 # define rtld_hidden_data_weak(name)
 579 # define rtld_hidden_data_ver(local, name)
 580 #endif
 581
 582 #if IS_IN (libm)
 583 # define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 584 # define libm_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 585 # define libm_hidden_def(name) hidden_def (name)
 586 # define libm_hidden_weak(name) hidden_weak (name)
 587 # define libm_hidden_ver(local, name) hidden_ver (local, name)
 588 # define libm_hidden_data_def(name) hidden_data_def (name)
 589 # define libm_hidden_data_weak(name) hidden_data_weak (name)
 590 # define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
 591 #else
 592 # define libm_hidden_proto(name, attrs...)
 593 # define libm_hidden_tls_proto(name, attrs...)
 594 # define libm_hidden_def(name)
 595 # define libm_hidden_weak(name)
 596 # define libm_hidden_ver(local, name)
 597 # define libm_hidden_data_def(name)
 598 # define libm_hidden_data_weak(name)
 599 # define libm_hidden_data_ver(local, name)
 600 #endif
 601
 602 #if IS_IN (libmvec)
 603 # define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 604 # define libmvec_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 605 # define libmvec_hidden_def(name) hidden_def (name)
 606 # define libmvec_hidden_weak(name) hidden_weak (name)
 607 # define libmvec_hidden_ver(local, name) hidden_ver (local, name)
 608 # define libmvec_hidden_data_def(name) hidden_data_def (name)
 609 # define libmvec_hidden_data_weak(name) hidden_data_weak (name)
 610 # define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
 611 #else
 612 # define libmvec_hidden_proto(name, attrs...)
 613 # define libmvec_hidden_tls_proto(name, attrs...)
 614 # define libmvec_hidden_def(name)
 615 # define libmvec_hidden_weak(name)
 616 # define libmvec_hidden_ver(local, name)
 617 # define libmvec_hidden_data_def(name)
 618 # define libmvec_hidden_data_weak(name)
 619 # define libmvec_hidden_data_ver(local, name)
 620 #endif
 621
 622 #if IS_IN (libresolv)
 623 # define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 624 # define libresolv_hidden_tls_proto(name, attrs...) \
 625   hidden_tls_proto (name, ##attrs)
 626 # define libresolv_hidden_def(name) hidden_def (name)
 627 # define libresolv_hidden_weak(name) hidden_weak (name)
 628 # define libresolv_hidden_ver(local, name) hidden_ver (local, name)
 629 # define libresolv_hidden_data_def(name) hidden_data_def (name)
 630 # define libresolv_hidden_data_weak(name) hidden_data_weak (name)
 631 # define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
 632 #else
 633 # define libresolv_hidden_proto(name, attrs...)
 634 # define libresolv_hidden_tls_proto(name, attrs...)
 635 # define libresolv_hidden_def(name)
 636 # define libresolv_hidden_weak(name)
 637 # define libresolv_hidden_ver(local, name)
 638 # define libresolv_hidden_data_def(name)
 639 # define libresolv_hidden_data_weak(name)
 640 # define libresolv_hidden_data_ver(local, name)
 641 #endif
 642
 643 #if IS_IN (librt)
 644 # define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 645 # define librt_hidden_tls_proto(name, attrs...) \
 646   hidden_tls_proto (name, ##attrs)
 647 # define librt_hidden_def(name) hidden_def (name)
 648 # define librt_hidden_weak(name) hidden_weak (name)
 649 # define librt_hidden_ver(local, name) hidden_ver (local, name)
 650 # define librt_hidden_data_def(name) hidden_data_def (name)
 651 # define librt_hidden_data_weak(name) hidden_data_weak (name)
 652 # define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
 653 #else
 654 # define librt_hidden_proto(name, attrs...)
 655 # define librt_hidden_tls_proto(name, attrs...)
 656 # define librt_hidden_def(name)
 657 # define librt_hidden_weak(name)
 658 # define librt_hidden_ver(local, name)
 659 # define librt_hidden_data_def(name)
 660 # define librt_hidden_data_weak(name)
 661 # define librt_hidden_data_ver(local, name)
 662 #endif
 663
 664 #if IS_IN (libdl)
 665 # define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 666 # define libdl_hidden_tls_proto(name, attrs...) \
 667   hidden_tls_proto (name, ##attrs)
 668 # define libdl_hidden_def(name) hidden_def (name)
 669 # define libdl_hidden_weak(name) hidden_weak (name)
 670 # define libdl_hidden_ver(local, name) hidden_ver (local, name)
 671 # define libdl_hidden_data_def(name) hidden_data_def (name)
 672 # define libdl_hidden_data_weak(name) hidden_data_weak (name)
 673 # define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
 674 #else
 675 # define libdl_hidden_proto(name, attrs...)
 676 # define libdl_hidden_tls_proto(name, attrs...)
 677 # define libdl_hidden_def(name)
 678 # define libdl_hidden_weak(name)
 679 # define libdl_hidden_ver(local, name)
 680 # define libdl_hidden_data_def(name)
 681 # define libdl_hidden_data_weak(name)
 682 # define libdl_hidden_data_ver(local, name)
 683 #endif
 684
 685 #if IS_IN (libnss_files)
 686 # define libnss_files_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 687 # define libnss_files_hidden_tls_proto(name, attrs...) \
 688   hidden_tls_proto (name, ##attrs)
 689 # define libnss_files_hidden_def(name) hidden_def (name)
 690 # define libnss_files_hidden_weak(name) hidden_weak (name)
 691 # define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
 692 # define libnss_files_hidden_data_def(name) hidden_data_def (name)
 693 # define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
 694 # define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
 695 #else
 696 # define libnss_files_hidden_proto(name, attrs...)
 697 # define libnss_files_hidden_tls_proto(name, attrs...)
 698 # define libnss_files_hidden_def(name)
 699 # define libnss_files_hidden_weak(name)
 700 # define libnss_files_hidden_ver(local, name)
 701 # define libnss_files_hidden_data_def(name)
 702 # define libnss_files_hidden_data_weak(name)
 703 # define libnss_files_hidden_data_ver(local, name)
 704 #endif
 705
 706 #if IS_IN (libnsl)
 707 # define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 708 # define libnsl_hidden_tls_proto(name, attrs...) \
 709   hidden_tls_proto (name, ##attrs)
 710 # ifdef LINK_OBSOLETE_NSL
 711    /* libnsl_hidden_nolink should only get used in libnsl code.  */
 712 #  define libnsl_hidden_nolink_def(name, version) libnsl_hidden_def (name)
 713 # else
 714 #  define libnsl_hidden_nolink_def(name, version) hidden_nolink (name, libnsl, version)
 715 # endif
 716 # define libnsl_hidden_def(name) hidden_def (name)
 717 # define libnsl_hidden_weak(name) hidden_weak (name)
 718 # define libnsl_hidden_ver(local, name) hidden_ver (local, name)
 719 # define libnsl_hidden_data_def(name) hidden_data_def (name)
 720 # define libnsl_hidden_data_weak(name) hidden_data_weak (name)
 721 # define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
 722 #else
 723 # define libnsl_hidden_proto(name, attrs...)
 724 # define libnsl_hidden_tls_proto(name, attrs...)
 725 # define libnsl_hidden_def(name)
 726 # define libnsl_hidden_weak(name)
 727 # define libnsl_hidden_ver(local, name)
 728 # define libnsl_hidden_data_def(name)
 729 # define libnsl_hidden_data_weak(name)
 730 # define libnsl_hidden_data_ver(local, name)
 731 #endif
 732
 733 #if IS_IN (libnss_nisplus)
 734 # define libnss_nisplus_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 735 # define libnss_nisplus_hidden_tls_proto(name, attrs...) \
 736   hidden_tls_proto (name, ##attrs)
 737 # define libnss_nisplus_hidden_def(name) hidden_def (name)
 738 # define libnss_nisplus_hidden_weak(name) hidden_weak (name)
 739 # define libnss_nisplus_hidden_ver(local, name) hidden_ver (local, name)
 740 # define libnss_nisplus_hidden_data_def(name) hidden_data_def (name)
 741 # define libnss_nisplus_hidden_data_weak(name) hidden_data_weak (name)
 742 # define libnss_nisplus_hidden_data_ver(local, name) hidden_data_ver (local, name)
 743 #else
 744 # define libnss_nisplus_hidden_proto(name, attrs...)
 745 # define libnss_nisplus_hidden_tls_proto(name, attrs...)
 746 # define libnss_nisplus_hidden_def(name)
 747 # define libnss_nisplus_hidden_weak(name)
 748 # define libnss_nisplus_hidden_ver(local, name)
 749 # define libnss_nisplus_hidden_data_def(name)
 750 # define libnss_nisplus_hidden_data_weak(name)
 751 # define libnss_nisplus_hidden_data_ver(local, name)
 752 #endif
 753
 754 #define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
 755 #define libc_hidden_builtin_def(name) libc_hidden_def (name)
 756 #define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
 757 #define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
 758 #ifdef __ASSEMBLER__
 759 # define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
 760 #endif
 761
 762 #if IS_IN (libutil)
 763 # define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 764 # define libutil_hidden_tls_proto(name, attrs...) \
 765   hidden_tls_proto (name, ##attrs)
 766 # define libutil_hidden_def(name) hidden_def (name)
 767 # define libutil_hidden_weak(name) hidden_weak (name)
 768 # define libutil_hidden_ver(local, name) hidden_ver (local, name)
 769 # define libutil_hidden_data_def(name) hidden_data_def (name)
 770 # define libutil_hidden_data_weak(name) hidden_data_weak (name)
 771 # define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
 772 #else
 773 # define libutil_hidden_proto(name, attrs...)
 774 # define libutil_hidden_tls_proto(name, attrs...)
 775 # define libutil_hidden_def(name)
 776 # define libutil_hidden_weak(name)
 777 # define libutil_hidden_ver(local, name)
 778 # define libutil_hidden_data_def(name)
 779 # define libutil_hidden_data_weak(name)
 780 # define libutil_hidden_data_ver(local, name)
 781 #endif
 782
 783 /* Get some dirty hacks.  */
 784 #include <symbol-hacks.h>
 785
 786 /* Move compatibility symbols out of the way by placing them all in a
 787    special section.  */
 788 #ifndef __ASSEMBLER__
 789 # define attribute_compat_text_section \
 790     __attribute__ ((section (".text.compat")))
 791 # define attribute_compat_data_section \
 792     __attribute__ ((section (".data.compat")))
 793 #else
 794 # define compat_text_section .section ".text.compat", "ax";
 795 # define compat_data_section .section ".data.compat", "aw";
 796 #endif
 797
 798 /* Helper / base  macros for indirect function symbols.  */
 799 #define __ifunc_resolver(type_name, name, expr, arg, init, classifier)  \
 800   classifier inhibit_stack_protector                                    \
 801   __typeof (type_name) *name##_ifunc (arg)                              \
 802   {                                                                     \
 803     init ();                                                            \
 804     __typeof (type_name) *res = expr;                                   \
 805     return res;                                                         \
 806   }
 807
 808 #ifdef HAVE_GCC_IFUNC
 809 # define __ifunc(type_name, name, expr, arg, init)                      \
 810   extern __typeof (type_name) name __attribute__                        \
 811                               ((ifunc (#name "_ifunc")));               \
 812   __ifunc_resolver (type_name, name, expr, arg, init, static)
 813
 814 # define __ifunc_hidden(type_name, name, expr, arg, init)       \
 815   __ifunc (type_name, name, expr, arg, init)
 816 #else
 817 /* Gcc does not support __attribute__ ((ifunc (...))).  Use the old behaviour
 818    as fallback.  But keep in mind that the debug information for the ifunc
 819    resolver functions is not correct.  It contains the ifunc'ed function as
 820    DW_AT_linkage_name.  E.g. lldb uses this field and an inferior function
 821    call of the ifunc'ed function will fail due to "no matching function for
 822    call to ..." because the ifunc'ed function and the resolver function have
 823    different signatures.  (Gcc support is disabled at least on a ppc64le
 824    Ubuntu 14.04 system.)  */
 825
 826 # define __ifunc(type_name, name, expr, arg, init)                      \
 827   extern __typeof (type_name) name;                                     \
 828   __typeof (type_name) *name##_ifunc (arg) __asm__ (#name);             \
 829   __ifunc_resolver (type_name, name, expr, arg, init,)                  \
 830  __asm__ (".type " #name ", %gnu_indirect_function");
 831
 832 # define __ifunc_hidden(type_name, name, expr, arg, init)               \
 833   extern __typeof (type_name) __libc_##name;                            \
 834   __ifunc (type_name, __libc_##name, expr, arg, init)                   \
 835   strong_alias (__libc_##name, name);
 836 #endif /* !HAVE_GCC_IFUNC  */
 837
 838 /* The following macros are used for indirect function symbols in libc.so.
 839    First of all, you need to have the function prototyped somewhere,
 840    say in foo.h:
 841
 842    int foo (int __bar);
 843
 844    If you have an implementation for foo which e.g. uses a special hardware
 845    feature which isn't available on all machines where this libc.so will be
 846    used but decideable if available at runtime e.g. via hwcaps, you can provide
 847    two or multiple implementations of foo:
 848
 849    int __foo_default (int __bar)
 850    {
 851      return __bar;
 852    }
 853
 854    int __foo_special (int __bar)
 855    {
 856      return __bar;
 857    }
 858
 859    If your function foo has no libc_hidden_proto (foo) defined for PLT
 860    bypassing, you can use:
 861
 862    #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
 863
 864    libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
 865
 866    This will define a resolver function for foo which returns __foo_special or
 867    __foo_default depending on your specified expression.  Please note that you
 868    have to define a macro function INIT_ARCH before using libc_ifunc macro as
 869    it is called by the resolver function before evaluating the specified
 870    expression.  In this example it is used to prepare the hwcap variable.
 871    The resolver function is assigned to an ifunc'ed symbol foo.  Calls to foo
 872    from inside or outside of libc.so will be indirected by a PLT call.
 873
 874    If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
 875    and calls to foo within libc.so should always go to one specific
 876    implementation of foo e.g. __foo_default then you have to add:
 877
 878    __hidden_ver1 (__foo_default, __GI_foo, __foo_default);
 879
 880    or a tweaked definition of libc_hidden_def macro after the __foo_default
 881    function definition.  Calls to foo within libc.so will always go directly to
 882    __foo_default.  Calls to foo from outside libc.so will be indirected by a
 883    PLT call to ifunc'ed symbol foo which you have to define in a separate
 884    compile unit:
 885
 886    #define foo __redirect_foo
 887    #include <foo.h>
 888    #undef foo
 889
 890    extern __typeof (__redirect_foo) __foo_default attribute_hidden;
 891    extern __typeof (__redirect_foo) __foo_special attribute_hidden;
 892
 893    libc_ifunc_redirected (__redirect_foo, foo,
 894                           (hwcap & HWCAP_SPECIAL)
 895                           ? __foo_special
 896                           : __foo_default);
 897
 898    This will define the ifunc'ed symbol foo like above.  The redirection of foo
 899    in header file is needed to omit an additional defintion of __GI_foo which
 900    would end in a linker error while linking libc.so.  You have to specify
 901    __redirect_foo as first parameter which is used within libc_ifunc_redirected
 902    macro in conjunction with typeof to define the ifunc'ed symbol foo.
 903
 904    If your function foo has a libc_hidden_proto (foo) defined and calls to foo
 905    within or from outside libc.so should go via ifunc'ed symbol, then you have
 906    to use:
 907
 908    libc_ifunc_hidden (foo, foo,
 909                       (hwcap & HWCAP_SPECIAL)
 910                       ? __foo_special
 911                       : __foo_default);
 912    libc_hidden_def (foo)
 913
 914    The first parameter foo of libc_ifunc_hidden macro is used in the same way
 915    as for libc_ifunc_redirected macro.  */
 916
 917 #define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
 918
 919 #define libc_ifunc_redirected(redirected_name, name, expr)      \
 920   __ifunc (redirected_name, name, expr, void, INIT_ARCH)
 921
 922 #define libc_ifunc_hidden(redirected_name, name, expr)                  \
 923   __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
 924
 925 /* The body of the function is supposed to use __get_cpu_features
 926    which will, if necessary, initialize the data first.  */
 927 #define libm_ifunc_init()
 928 #define libm_ifunc(name, expr)                          \
 929   __ifunc (name, name, expr, void, libm_ifunc_init)
 930
 931 /* Add the compiler optimization to inhibit loop transformation to library
 932    calls.  This is used to avoid recursive calls in memset and memmove
 933    default implementations.  */
 934 #ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
 935 # define inhibit_loop_to_libcall \
 936     __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
 937 #else
 938 # define inhibit_loop_to_libcall
 939 #endif
 940 \f
 941 /* These macros facilitate sharing source files with gnulib.
 942
 943    They are here instead of sys/cdefs.h because they should not be
 944    used in public header files.
 945
 946    Their definitions should be kept consistent with the definitions in
 947    gnulib-common.m4, but it is not necessary to cater to old non-GCC
 948    compilers, since they will only be used while building glibc itself.
 949    (Note that _GNUC_PREREQ cannot be used in this file.)  */
 950
 951 /* Define as a marker that can be attached to declarations that might not
 952     be used.  This helps to reduce warnings, such as from
 953     GCC -Wunused-parameter.  */
 954 #if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
 955 # define _GL_UNUSED __attribute__ ((__unused__))
 956 #else
 957 # define _GL_UNUSED
 958 #endif
 959
 960 /* gcc supports the "unused" attribute on possibly unused labels, and
 961    g++ has since version 4.5.  Note to support C++ as well as C,
 962    _GL_UNUSED_LABEL should be used with a trailing ;  */
 963 #if !defined __cplusplus || __GNUC__ > 4 \
 964     || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
 965 # define _GL_UNUSED_LABEL _GL_UNUSED
 966 #else
 967 # define _GL_UNUSED_LABEL
 968 #endif
 969
 970 /* The __pure__ attribute was added in gcc 2.96.  */
 971 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
 972 # define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
 973 #else
 974 # define _GL_ATTRIBUTE_PURE /* empty */
 975 #endif
 976
 977 /* The __const__ attribute was added in gcc 2.95.  */
 978 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
 979 # define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
 980 #else
 981 # define _GL_ATTRIBUTE_CONST /* empty */
 982 #endif
 983
 984 #endif /* !_ISOMAC */
 985 #endif /* libc-symbols.h */