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