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) 1995-2016 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 #define IN_MODULE PASTE_NAME (MODULE_, MODULE_NAME)
  24 #define IS_IN(lib) (IN_MODULE == MODULE_##lib)
  25
  26 /* Returns true if the current module is a versioned library.  Versioned
  27    library names culled from shlib-versions files are assigned a MODULE_*
  28    value lower than MODULE_LIBS_BEGIN.  */
  29 #define IS_IN_LIB (IN_MODULE > MODULE_LIBS_BEGIN)
  30
  31 #define PASTE_NAME(a,b)      PASTE_NAME1 (a,b)
  32 #define PASTE_NAME1(a,b)     a##b
  33
  34 /* This file's macros are included implicitly in the compilation of every
  35    file in the C library by -imacros.
  36
  37    We include config.h which is generated by configure.
  38    It should define for us the following symbol:
  39
  40    * HAVE_ASM_SET_DIRECTIVE if we have `.set B, A' instead of `A = B'.
  41
  42    */
  43
  44 /* This is defined for the compilation of all C library code.  features.h
  45    tests this to avoid inclusion of stubs.h while compiling the library,
  46    before stubs.h has been generated.  Some library code that is shared
  47    with other packages also tests this symbol to see if it is being
  48    compiled as part of the C library.  We must define this before including
  49    config.h, because it makes some definitions conditional on whether libc
  50    itself is being compiled, or just some generator program.  */
  51 #define _LIBC   1
  52
  53 /* Enable declarations of GNU extensions, since we are compiling them.  */
  54 #define _GNU_SOURCE     1
  55
  56 #include <config.h>
  57
  58 /* Define this for the benefit of portable GNU code that wants to check it.
  59    Code that checks with #if will not #include <config.h> again, since we've
  60    already done it (and this file is implicitly included in every compile,
  61    via -include).  Code that checks with #ifdef will #include <config.h>,
  62    but that file should always be idempotent (i.e., it's just #define/#undef
  63    and nothing else anywhere should be changing the macro state it touches),
  64    so it's harmless.  */
  65 #define HAVE_CONFIG_H   0
  66
  67 /* Define these macros for the benefit of portable GNU code that wants to check
  68    them.  Of course, STDC_HEADERS is never false when building libc!  */
  69 #define STDC_HEADERS    1
  70 #define HAVE_MBSTATE_T  1
  71 #define HAVE_MBSRTOWCS  1
  72 #define HAVE_LIBINTL_H  1
  73 #define HAVE_WCTYPE_H   1
  74 #define HAVE_ISWCTYPE   1
  75 #define ENABLE_NLS      1
  76
  77 /* The symbols in all the user (non-_) macros are C symbols.  */
  78
  79 #ifndef __SYMBOL_PREFIX
  80 # define __SYMBOL_PREFIX
  81 #endif
  82
  83 #ifndef C_SYMBOL_NAME
  84 # define C_SYMBOL_NAME(name) name
  85 #endif
  86
  87 #ifndef ASM_LINE_SEP
  88 # define ASM_LINE_SEP ;
  89 #endif
  90
  91 #ifndef __ASSEMBLER__
  92 /* GCC understands weak symbols and aliases; use its interface where
  93    possible, instead of embedded assembly language.  */
  94
  95 /* Define ALIASNAME as a strong alias for NAME.  */
  96 # define strong_alias(name, aliasname) _strong_alias(name, aliasname)
  97 # define _strong_alias(name, aliasname) \
  98   extern __typeof (name) aliasname __attribute__ ((alias (#name)));
  99
 100 /* This comes between the return type and function name in
 101    a function definition to make that definition weak.  */
 102 # define weak_function __attribute__ ((weak))
 103 # define weak_const_function __attribute__ ((weak, __const__))
 104
 105 /* Define ALIASNAME as a weak alias for NAME.
 106    If weak aliases are not available, this defines a strong alias.  */
 107 # define weak_alias(name, aliasname) _weak_alias (name, aliasname)
 108 # define _weak_alias(name, aliasname) \
 109   extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
 110
 111 /* Same as WEAK_ALIAS, but mark symbol as hidden.  */
 112 # define weak_hidden_alias(name, aliasname) \
 113   _weak_hidden_alias (name, aliasname)
 114 # define _weak_hidden_alias(name, aliasname) \
 115   extern __typeof (name) aliasname \
 116     __attribute__ ((weak, alias (#name), __visibility__ ("hidden")));
 117
 118 /* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined).  */
 119 # define weak_extern(symbol) _weak_extern (weak symbol)
 120 # define _weak_extern(expr) _Pragma (#expr)
 121
 122 /* In shared builds, the expression call_function_static_weak
 123    (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
 124    identifier) unconditionally, with the (potentially empty) argument
 125    list ARGUMENTS.  In static builds, if FUNCTION-SYMBOL has a
 126    definition, the function is invoked as before; if FUNCTION-SYMBOL
 127    is NULL, no call is performed.  */
 128 # ifdef SHARED
 129 #  define call_function_static_weak(func, ...) func (__VA_ARGS__)
 130 # else  /* !SHARED */
 131 #  define call_function_static_weak(func, ...)          \
 132   ({                                                    \
 133     extern __typeof__ (func) func weak_function;        \
 134     (func != NULL ? func (__VA_ARGS__) : (void)0);      \
 135   })
 136 # endif
 137
 138 #else /* __ASSEMBLER__ */
 139
 140 # ifdef HAVE_ASM_SET_DIRECTIVE
 141 #  define strong_alias(original, alias)                         \
 142   .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP             \
 143   .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
 144 #  define strong_data_alias(original, alias) strong_alias(original, alias)
 145 # else
 146 #  define strong_alias(original, alias)                         \
 147   .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP             \
 148   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 149 #  define strong_data_alias(original, alias) strong_alias(original, alias)
 150 # endif
 151
 152 # define weak_alias(original, alias)                                    \
 153   .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP                              \
 154   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 155
 156 # define weak_extern(symbol)                                            \
 157   .weak C_SYMBOL_NAME (symbol)
 158
 159 #endif /* __ASSEMBLER__ */
 160
 161 /* On some platforms we can make internal function calls (i.e., calls of
 162    functions not exported) a bit faster by using a different calling
 163    convention.  */
 164 #ifndef internal_function
 165 # define internal_function      /* empty */
 166 #endif
 167
 168 /* Determine the return address.  */
 169 #define RETURN_ADDRESS(nr) \
 170   __builtin_extract_return_addr (__builtin_return_address (nr))
 171
 172 /* When a reference to SYMBOL is encountered, the linker will emit a
 173    warning message MSG.  */
 174 /* We want the .gnu.warning.SYMBOL section to be unallocated.  */
 175 #define __make_section_unallocated(section_string)      \
 176   asm (".section " section_string "\n\t.previous");
 177
 178 /* Tacking on "\n\t#" to the section name makes gcc put it's bogus
 179    section attributes on what looks like a comment to the assembler.  */
 180 #ifdef HAVE_SECTION_QUOTES
 181 # define __sec_comment "\"\n\t#\""
 182 #else
 183 # define __sec_comment "\n\t#"
 184 #endif
 185 #define link_warning(symbol, msg) \
 186   __make_section_unallocated (".gnu.warning." #symbol) \
 187   static const char __evoke_link_warning_##symbol[]     \
 188     __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
 189     = msg;
 190 #define libc_freeres_ptr(decl) \
 191   __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
 192   decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
 193 #define __libc_freeres_fn_section \
 194   __attribute__ ((section ("__libc_freeres_fn")))
 195
 196 #define libc_freeres_fn(name)   \
 197   static void name (void) __attribute_used__ __libc_freeres_fn_section; \
 198   text_set_element (__libc_subfreeres, name);                           \
 199   static void name (void)
 200
 201 /* A canned warning for sysdeps/stub functions.  */
 202 #define stub_warning(name) \
 203   __make_section_unallocated (".gnu.glibc-stub." #name) \
 204   link_warning (name, #name " is not implemented and will always fail")
 205
 206 /* Warning for linking functions calling dlopen into static binaries.  */
 207 #ifdef SHARED
 208 #define static_link_warning(name)
 209 #else
 210 #define static_link_warning(name) static_link_warning1(name)
 211 #define static_link_warning1(name) \
 212   link_warning(name, "Using '" #name "' in statically linked applications \
 213 requires at runtime the shared libraries from the glibc version used \
 214 for linking")
 215 #endif
 216
 217 /* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
 218    alias to ORIGINAL, when the assembler supports such declarations
 219    (such as in ELF).
 220    This is only necessary when defining something in assembly, or playing
 221    funny alias games where the size should be other than what the compiler
 222    thinks it is.  */
 223 #define declare_symbol_alias(symbol, original, type, size) \
 224   declare_symbol_alias_1 (symbol, original, type, size)
 225 #ifdef __ASSEMBLER__
 226 # define declare_symbol_alias_1(symbol, original, type, size) \
 227    strong_alias (original, symbol); \
 228    .type C_SYMBOL_NAME (symbol), %##type; \
 229    .size C_SYMBOL_NAME (symbol), size
 230 #else /* Not __ASSEMBLER__.  */
 231 # define declare_symbol_alias_1(symbol, original, type, size) \
 232    asm (".globl " __SYMBOL_PREFIX #symbol \
 233         "\n\t" declare_symbol_alias_1_alias (symbol, original) \
 234         "\n\t.type " __SYMBOL_PREFIX #symbol ", " \
 235         "%" #type \
 236         "\n\t.size " __SYMBOL_PREFIX #symbol ", " #size);
 237 # ifdef HAVE_ASM_SET_DIRECTIVE
 238 #  define declare_symbol_alias_1_alias(symbol, original) \
 239      ".set " __SYMBOL_PREFIX #symbol ", " __SYMBOL_PREFIX #original
 240 # else
 241 #  define declare_symbol_alias_1_alias(symbol, original) \
 242      __SYMBOL_PREFIX #symbol " = " __SYMBOL_PREFIX #original
 243 # endif /* HAVE_ASM_SET_DIRECTIVE */
 244 #endif /* __ASSEMBLER__ */
 245
 246
 247 /*
 248 \f
 249 */
 250
 251 /* Symbol set support macros.  */
 252
 253 /* Make SYMBOL, which is in the text segment, an element of SET.  */
 254 #define text_set_element(set, symbol)   _elf_set_element(set, symbol)
 255 /* Make SYMBOL, which is in the data segment, an element of SET.  */
 256 #define data_set_element(set, symbol)   _elf_set_element(set, symbol)
 257 /* Make SYMBOL, which is in the bss segment, an element of SET.  */
 258 #define bss_set_element(set, symbol)    _elf_set_element(set, symbol)
 259
 260 /* These are all done the same way in ELF.
 261    There is a new section created for each set.  */
 262 #ifdef SHARED
 263 /* When building a shared library, make the set section writable,
 264    because it will need to be relocated at run time anyway.  */
 265 # define _elf_set_element(set, symbol) \
 266   static const void *__elf_set_##set##_element_##symbol##__ \
 267     __attribute__ ((used, section (#set))) = &(symbol)
 268 #else
 269 # define _elf_set_element(set, symbol) \
 270   static const void *const __elf_set_##set##_element_##symbol##__ \
 271     __attribute__ ((used, section (#set))) = &(symbol)
 272 #endif
 273
 274 /* Define SET as a symbol set.  This may be required (it is in a.out) to
 275    be able to use the set's contents.  */
 276 #define symbol_set_define(set)  symbol_set_declare(set)
 277
 278 /* Declare SET for use in this module, if defined in another module.
 279    In a shared library, this is always local to that shared object.
 280    For static linking, the set might be wholly absent and so we use
 281    weak references.  */
 282 #define symbol_set_declare(set) \
 283   extern char const __start_##set[] __symbol_set_attribute; \
 284   extern char const __stop_##set[] __symbol_set_attribute;
 285 #ifdef SHARED
 286 # define __symbol_set_attribute attribute_hidden
 287 #else
 288 # define __symbol_set_attribute __attribute__ ((weak))
 289 #endif
 290
 291 /* Return a pointer (void *const *) to the first element of SET.  */
 292 #define symbol_set_first_element(set)   ((void *const *) (&__start_##set))
 293
 294 /* Return true iff PTR (a void *const *) has been incremented
 295    past the last element in SET.  */
 296 #define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
 297
 298 /* Use symbol_version_reference to specify the version a symbol
 299    reference should link to.  Use symbol_version or
 300    default_symbol_version for the definition of a versioned symbol.
 301    The difference is that the latter is a no-op in non-shared
 302    builds.  */
 303 #ifdef __ASSEMBLER__
 304 # define symbol_version_reference(real, name, version) \
 305      .symver real, name##@##version
 306 #else  /* !__ASSEMBLER__ */
 307 # define symbol_version_reference(real, name, version) \
 308   __asm__ (".symver " #real "," #name "@" #version)
 309 #endif
 310
 311 #ifdef SHARED
 312 # define symbol_version(real, name, version) \
 313   symbol_version_reference(real, name, version)
 314 # define default_symbol_version(real, name, version) \
 315      _default_symbol_version(real, name, version)
 316 # ifdef __ASSEMBLER__
 317 #  define _default_symbol_version(real, name, version) \
 318      .symver real, name##@##@##version
 319 # else
 320 #  define _default_symbol_version(real, name, version) \
 321      __asm__ (".symver " #real "," #name "@@" #version)
 322 # endif
 323 #else
 324 # define symbol_version(real, name, version)
 325 # define default_symbol_version(real, name, version) \
 326   strong_alias(real, name)
 327 #endif
 328
 329 #if defined SHARED || defined LIBC_NONSHARED
 330 # define attribute_hidden __attribute__ ((visibility ("hidden")))
 331 #else
 332 # define attribute_hidden
 333 #endif
 334
 335 #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
 336
 337 #define attribute_relro __attribute__ ((section (".data.rel.ro")))
 338
 339 /* The following macros are used for PLT bypassing within libc.so
 340    (and if needed other libraries similarly).
 341    First of all, you need to have the function prototyped somewhere,
 342    say in foo/foo.h:
 343
 344    int foo (int __bar);
 345
 346    If calls to foo within libc.so should always go to foo defined in libc.so,
 347    then in include/foo.h you add:
 348
 349    libc_hidden_proto (foo)
 350
 351    line and after the foo function definition:
 352
 353    int foo (int __bar)
 354    {
 355      return __bar;
 356    }
 357    libc_hidden_def (foo)
 358
 359    or
 360
 361    int foo (int __bar)
 362    {
 363      return __bar;
 364    }
 365    libc_hidden_weak (foo)
 366
 367    Similarly for global data.  If references to foo within libc.so should
 368    always go to foo defined in libc.so, then in include/foo.h you add:
 369
 370    libc_hidden_proto (foo)
 371
 372    line and after foo's definition:
 373
 374    int foo = INITIAL_FOO_VALUE;
 375    libc_hidden_data_def (foo)
 376
 377    or
 378
 379    int foo = INITIAL_FOO_VALUE;
 380    libc_hidden_data_weak (foo)
 381
 382    If foo is normally just an alias (strong or weak) to some other function,
 383    you should use the normal strong_alias first, then add libc_hidden_def
 384    or libc_hidden_weak:
 385
 386    int baz (int __bar)
 387    {
 388      return __bar;
 389    }
 390    strong_alias (baz, foo)
 391    libc_hidden_weak (foo)
 392
 393    If the function should be internal to multiple objects, say ld.so and
 394    libc.so, the best way is to use:
 395
 396    #if IS_IN (libc) || IS_IN (rtld)
 397    hidden_proto (foo)
 398    #endif
 399
 400    in include/foo.h and the normal macros at all function definitions
 401    depending on what DSO they belong to.
 402
 403    If versioned_symbol macro is used to define foo,
 404    libc_hidden_ver macro should be used, as in:
 405
 406    int __real_foo (int __bar)
 407    {
 408      return __bar;
 409    }
 410    versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
 411    libc_hidden_ver (__real_foo, foo)  */
 412
 413 #if defined SHARED && !defined NO_HIDDEN
 414 # ifndef __ASSEMBLER__
 415 #  define __hidden_proto_hiddenattr(attrs...) \
 416   __attribute__ ((visibility ("hidden"), ##attrs))
 417 #  define hidden_proto(name, attrs...) \
 418   __hidden_proto (name, , __GI_##name, ##attrs)
 419 #  define hidden_tls_proto(name, attrs...) \
 420   __hidden_proto (name, __thread, __GI_##name, ##attrs)
 421 #  define __hidden_proto(name, thread, internal, attrs...)           \
 422   extern thread __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
 423   __hidden_proto_hiddenattr (attrs);
 424 #  define __hidden_asmname(name) \
 425   __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
 426 #  define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
 427 #  define __hidden_asmname2(prefix, name) #prefix name
 428 #  define __hidden_ver1(local, internal, name) \
 429   extern __typeof (name) __EI_##name __asm__(__hidden_asmname (#internal)); \
 430   extern __typeof (name) __EI_##name \
 431         __attribute__((alias (__hidden_asmname (#local))))
 432 #  define hidden_ver(local, name)       __hidden_ver1(local, __GI_##name, name);
 433 #  define hidden_data_ver(local, name)  hidden_ver(local, name)
 434 #  define hidden_def(name)              __hidden_ver1(__GI_##name, name, name);
 435 #  define hidden_data_def(name)         hidden_def(name)
 436 #  define hidden_weak(name) \
 437         __hidden_ver1(__GI_##name, name, name) __attribute__((weak));
 438 #  define hidden_data_weak(name)        hidden_weak(name)
 439 #  define hidden_nolink(name, lib, version) \
 440   __hidden_nolink1 (__GI_##name, __EI_##name, name, VERSION_##lib##_##version)
 441 #  define __hidden_nolink1(local, internal, name, version) \
 442   __hidden_nolink2 (local, internal, name, version)
 443 #  define __hidden_nolink2(local, internal, name, version) \
 444   extern __typeof (name) internal __attribute__ ((alias (#local))); \
 445   __hidden_nolink3 (local, internal, #name "@" #version)
 446 #  define __hidden_nolink3(local, internal, vername) \
 447   __asm__ (".symver " #internal ", " vername);
 448 # else
 449 /* For assembly, we need to do the opposite of what we do in C:
 450    in assembly gcc __REDIRECT stuff is not in place, so functions
 451    are defined by its normal name and we need to create the
 452    __GI_* alias to it, in C __REDIRECT causes the function definition
 453    to use __GI_* name and we need to add alias to the real name.
 454    There is no reason to use hidden_weak over hidden_def in assembly,
 455    but we provide it for consistency with the C usage.
 456    hidden_proto doesn't make sense for assembly but the equivalent
 457    is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET.  */
 458 #  define hidden_def(name)      strong_alias (name, __GI_##name)
 459 #  define hidden_weak(name)     hidden_def (name)
 460 #  define hidden_ver(local, name) strong_alias (local, __GI_##name)
 461 #  define hidden_data_def(name) strong_data_alias (name, __GI_##name)
 462 #  define hidden_data_weak(name)        hidden_data_def (name)
 463 #  define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
 464 #  define HIDDEN_JUMPTARGET(name) __GI_##name
 465 # endif
 466 #else
 467 # ifndef __ASSEMBLER__
 468 #  define hidden_proto(name, attrs...)
 469 #  define hidden_tls_proto(name, attrs...)
 470 # else
 471 #  define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
 472 # endif /* Not  __ASSEMBLER__ */
 473 # define hidden_weak(name)
 474 # define hidden_def(name)
 475 # define hidden_ver(local, name)
 476 # define hidden_data_weak(name)
 477 # define hidden_data_def(name)
 478 # define hidden_data_ver(local, name)
 479 # define hidden_nolink(name, lib, version)
 480 #endif
 481
 482 #if IS_IN (libc)
 483 # define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 484 # define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 485 # define libc_hidden_def(name) hidden_def (name)
 486 # define libc_hidden_weak(name) hidden_weak (name)
 487 # ifdef LINK_OBSOLETE_RPC
 488    /* libc_hidden_nolink_sunrpc should only get used in sunrpc code.  */
 489 #  define libc_hidden_nolink_sunrpc(name, version) hidden_def (name)
 490 # else
 491 #  define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
 492 # endif
 493 # define libc_hidden_ver(local, name) hidden_ver (local, name)
 494 # define libc_hidden_data_def(name) hidden_data_def (name)
 495 # define libc_hidden_data_weak(name) hidden_data_weak (name)
 496 # define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
 497 #else
 498 # define libc_hidden_proto(name, attrs...)
 499 # define libc_hidden_tls_proto(name, attrs...)
 500 # define libc_hidden_def(name)
 501 # define libc_hidden_weak(name)
 502 # define libc_hidden_ver(local, name)
 503 # define libc_hidden_data_def(name)
 504 # define libc_hidden_data_weak(name)
 505 # define libc_hidden_data_ver(local, name)
 506 #endif
 507
 508 #if IS_IN (rtld)
 509 # define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 510 # define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 511 # define rtld_hidden_def(name) hidden_def (name)
 512 # define rtld_hidden_weak(name) hidden_weak (name)
 513 # define rtld_hidden_ver(local, name) hidden_ver (local, name)
 514 # define rtld_hidden_data_def(name) hidden_data_def (name)
 515 # define rtld_hidden_data_weak(name) hidden_data_weak (name)
 516 # define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
 517 #else
 518 # define rtld_hidden_proto(name, attrs...)
 519 # define rtld_hidden_tls_proto(name, attrs...)
 520 # define rtld_hidden_def(name)
 521 # define rtld_hidden_weak(name)
 522 # define rtld_hidden_ver(local, name)
 523 # define rtld_hidden_data_def(name)
 524 # define rtld_hidden_data_weak(name)
 525 # define rtld_hidden_data_ver(local, name)
 526 #endif
 527
 528 #if IS_IN (libm)
 529 # define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 530 # define libm_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 531 # define libm_hidden_def(name) hidden_def (name)
 532 # define libm_hidden_weak(name) hidden_weak (name)
 533 # define libm_hidden_ver(local, name) hidden_ver (local, name)
 534 # define libm_hidden_data_def(name) hidden_data_def (name)
 535 # define libm_hidden_data_weak(name) hidden_data_weak (name)
 536 # define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
 537 #else
 538 # define libm_hidden_proto(name, attrs...)
 539 # define libm_hidden_tls_proto(name, attrs...)
 540 # define libm_hidden_def(name)
 541 # define libm_hidden_weak(name)
 542 # define libm_hidden_ver(local, name)
 543 # define libm_hidden_data_def(name)
 544 # define libm_hidden_data_weak(name)
 545 # define libm_hidden_data_ver(local, name)
 546 #endif
 547
 548 #if IS_IN (libmvec)
 549 # define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 550 # define libmvec_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 551 # define libmvec_hidden_def(name) hidden_def (name)
 552 # define libmvec_hidden_weak(name) hidden_weak (name)
 553 # define libmvec_hidden_ver(local, name) hidden_ver (local, name)
 554 # define libmvec_hidden_data_def(name) hidden_data_def (name)
 555 # define libmvec_hidden_data_weak(name) hidden_data_weak (name)
 556 # define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
 557 #else
 558 # define libmvec_hidden_proto(name, attrs...)
 559 # define libmvec_hidden_tls_proto(name, attrs...)
 560 # define libmvec_hidden_def(name)
 561 # define libmvec_hidden_weak(name)
 562 # define libmvec_hidden_ver(local, name)
 563 # define libmvec_hidden_data_def(name)
 564 # define libmvec_hidden_data_weak(name)
 565 # define libmvec_hidden_data_ver(local, name)
 566 #endif
 567
 568 #if IS_IN (libresolv)
 569 # define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 570 # define libresolv_hidden_tls_proto(name, attrs...) \
 571   hidden_tls_proto (name, ##attrs)
 572 # define libresolv_hidden_def(name) hidden_def (name)
 573 # define libresolv_hidden_weak(name) hidden_weak (name)
 574 # define libresolv_hidden_ver(local, name) hidden_ver (local, name)
 575 # define libresolv_hidden_data_def(name) hidden_data_def (name)
 576 # define libresolv_hidden_data_weak(name) hidden_data_weak (name)
 577 # define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
 578 #else
 579 # define libresolv_hidden_proto(name, attrs...)
 580 # define libresolv_hidden_tls_proto(name, attrs...)
 581 # define libresolv_hidden_def(name)
 582 # define libresolv_hidden_weak(name)
 583 # define libresolv_hidden_ver(local, name)
 584 # define libresolv_hidden_data_def(name)
 585 # define libresolv_hidden_data_weak(name)
 586 # define libresolv_hidden_data_ver(local, name)
 587 #endif
 588
 589 #if IS_IN (librt)
 590 # define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 591 # define librt_hidden_tls_proto(name, attrs...) \
 592   hidden_tls_proto (name, ##attrs)
 593 # define librt_hidden_def(name) hidden_def (name)
 594 # define librt_hidden_weak(name) hidden_weak (name)
 595 # define librt_hidden_ver(local, name) hidden_ver (local, name)
 596 # define librt_hidden_data_def(name) hidden_data_def (name)
 597 # define librt_hidden_data_weak(name) hidden_data_weak (name)
 598 # define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
 599 #else
 600 # define librt_hidden_proto(name, attrs...)
 601 # define librt_hidden_tls_proto(name, attrs...)
 602 # define librt_hidden_def(name)
 603 # define librt_hidden_weak(name)
 604 # define librt_hidden_ver(local, name)
 605 # define librt_hidden_data_def(name)
 606 # define librt_hidden_data_weak(name)
 607 # define librt_hidden_data_ver(local, name)
 608 #endif
 609
 610 #if IS_IN (libdl)
 611 # define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 612 # define libdl_hidden_tls_proto(name, attrs...) \
 613   hidden_tls_proto (name, ##attrs)
 614 # define libdl_hidden_def(name) hidden_def (name)
 615 # define libdl_hidden_weak(name) hidden_weak (name)
 616 # define libdl_hidden_ver(local, name) hidden_ver (local, name)
 617 # define libdl_hidden_data_def(name) hidden_data_def (name)
 618 # define libdl_hidden_data_weak(name) hidden_data_weak (name)
 619 # define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
 620 #else
 621 # define libdl_hidden_proto(name, attrs...)
 622 # define libdl_hidden_tls_proto(name, attrs...)
 623 # define libdl_hidden_def(name)
 624 # define libdl_hidden_weak(name)
 625 # define libdl_hidden_ver(local, name)
 626 # define libdl_hidden_data_def(name)
 627 # define libdl_hidden_data_weak(name)
 628 # define libdl_hidden_data_ver(local, name)
 629 #endif
 630
 631 #if IS_IN (libnss_files)
 632 # define libnss_files_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 633 # define libnss_files_hidden_tls_proto(name, attrs...) \
 634   hidden_tls_proto (name, ##attrs)
 635 # define libnss_files_hidden_def(name) hidden_def (name)
 636 # define libnss_files_hidden_weak(name) hidden_weak (name)
 637 # define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
 638 # define libnss_files_hidden_data_def(name) hidden_data_def (name)
 639 # define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
 640 # define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
 641 #else
 642 # define libnss_files_hidden_proto(name, attrs...)
 643 # define libnss_files_hidden_tls_proto(name, attrs...)
 644 # define libnss_files_hidden_def(name)
 645 # define libnss_files_hidden_weak(name)
 646 # define libnss_files_hidden_ver(local, name)
 647 # define libnss_files_hidden_data_def(name)
 648 # define libnss_files_hidden_data_weak(name)
 649 # define libnss_files_hidden_data_ver(local, name)
 650 #endif
 651
 652 #if IS_IN (libnsl)
 653 # define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 654 # define libnsl_hidden_tls_proto(name, attrs...) \
 655   hidden_tls_proto (name, ##attrs)
 656 # define libnsl_hidden_def(name) hidden_def (name)
 657 # define libnsl_hidden_weak(name) hidden_weak (name)
 658 # define libnsl_hidden_ver(local, name) hidden_ver (local, name)
 659 # define libnsl_hidden_data_def(name) hidden_data_def (name)
 660 # define libnsl_hidden_data_weak(name) hidden_data_weak (name)
 661 # define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
 662 #else
 663 # define libnsl_hidden_proto(name, attrs...)
 664 # define libnsl_hidden_tls_proto(name, attrs...)
 665 # define libnsl_hidden_def(name)
 666 # define libnsl_hidden_weak(name)
 667 # define libnsl_hidden_ver(local, name)
 668 # define libnsl_hidden_data_def(name)
 669 # define libnsl_hidden_data_weak(name)
 670 # define libnsl_hidden_data_ver(local, name)
 671 #endif
 672
 673 #if IS_IN (libnss_nisplus)
 674 # define libnss_nisplus_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 675 # define libnss_nisplus_hidden_tls_proto(name, attrs...) \
 676   hidden_tls_proto (name, ##attrs)
 677 # define libnss_nisplus_hidden_def(name) hidden_def (name)
 678 # define libnss_nisplus_hidden_weak(name) hidden_weak (name)
 679 # define libnss_nisplus_hidden_ver(local, name) hidden_ver (local, name)
 680 # define libnss_nisplus_hidden_data_def(name) hidden_data_def (name)
 681 # define libnss_nisplus_hidden_data_weak(name) hidden_data_weak (name)
 682 # define libnss_nisplus_hidden_data_ver(local, name) hidden_data_ver (local, name)
 683 #else
 684 # define libnss_nisplus_hidden_proto(name, attrs...)
 685 # define libnss_nisplus_hidden_tls_proto(name, attrs...)
 686 # define libnss_nisplus_hidden_def(name)
 687 # define libnss_nisplus_hidden_weak(name)
 688 # define libnss_nisplus_hidden_ver(local, name)
 689 # define libnss_nisplus_hidden_data_def(name)
 690 # define libnss_nisplus_hidden_data_weak(name)
 691 # define libnss_nisplus_hidden_data_ver(local, name)
 692 #endif
 693
 694 #define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
 695 #define libc_hidden_builtin_def(name) libc_hidden_def (name)
 696 #define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
 697 #define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
 698 #ifdef __ASSEMBLER__
 699 # define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
 700 #endif
 701
 702 #if IS_IN (libutil)
 703 # define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 704 # define libutil_hidden_tls_proto(name, attrs...) \
 705   hidden_tls_proto (name, ##attrs)
 706 # define libutil_hidden_def(name) hidden_def (name)
 707 # define libutil_hidden_weak(name) hidden_weak (name)
 708 # define libutil_hidden_ver(local, name) hidden_ver (local, name)
 709 # define libutil_hidden_data_def(name) hidden_data_def (name)
 710 # define libutil_hidden_data_weak(name) hidden_data_weak (name)
 711 # define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
 712 #else
 713 # define libutil_hidden_proto(name, attrs...)
 714 # define libutil_hidden_tls_proto(name, attrs...)
 715 # define libutil_hidden_def(name)
 716 # define libutil_hidden_weak(name)
 717 # define libutil_hidden_ver(local, name)
 718 # define libutil_hidden_data_def(name)
 719 # define libutil_hidden_data_weak(name)
 720 # define libutil_hidden_data_ver(local, name)
 721 #endif
 722
 723 /* Get some dirty hacks.  */
 724 #include <symbol-hacks.h>
 725
 726 /* Move compatibility symbols out of the way by placing them all in a
 727    special section.  */
 728 #ifndef __ASSEMBLER__
 729 # define attribute_compat_text_section \
 730     __attribute__ ((section (".text.compat")))
 731 # define attribute_compat_data_section \
 732     __attribute__ ((section (".data.compat")))
 733 #else
 734 # define compat_text_section .section ".text.compat", "ax";
 735 # define compat_data_section .section ".data.compat", "aw";
 736 #endif
 737
 738 /* Helper / base  macros for indirect function symbols.  */
 739 #define __ifunc_resolver(type_name, name, expr, arg, init, classifier)  \
 740   classifier void *name##_ifunc (arg)                                   \
 741   {                                                                     \
 742     init ();                                                            \
 743     __typeof (type_name) *res = expr;                                   \
 744     return res;                                                         \
 745   }
 746
 747 #ifdef HAVE_GCC_IFUNC
 748 # define __ifunc(type_name, name, expr, arg, init)                      \
 749   extern __typeof (type_name) name __attribute__                        \
 750                               ((ifunc (#name "_ifunc")));               \
 751   __ifunc_resolver (type_name, name, expr, arg, init, static)
 752
 753 # define __ifunc_hidden(type_name, name, expr, arg, init)       \
 754   __ifunc (type_name, name, expr, arg, init)
 755 #else
 756 /* Gcc does not support __attribute__ ((ifunc (...))).  Use the old behaviour
 757    as fallback.  But keep in mind that the debug information for the ifunc
 758    resolver functions is not correct.  It contains the ifunc'ed function as
 759    DW_AT_linkage_name.  E.g. lldb uses this field and an inferior function
 760    call of the ifunc'ed function will fail due to "no matching function for
 761    call to ..." because the ifunc'ed function and the resolver function have
 762    different signatures.  (Gcc support is disabled at least on a ppc64le
 763    Ubuntu 14.04 system.)  */
 764
 765 # define __ifunc(type_name, name, expr, arg, init)                      \
 766   extern __typeof (type_name) name;                                     \
 767   void *name##_ifunc (arg) __asm__ (#name);                             \
 768   __ifunc_resolver (type_name, name, expr, arg, init,)                  \
 769  __asm__ (".type " #name ", %gnu_indirect_function");
 770
 771 # define __ifunc_hidden(type_name, name, expr, arg, init)               \
 772   extern __typeof (type_name) __libc_##name;                            \
 773   __ifunc (type_name, __libc_##name, expr, arg, init)                   \
 774   strong_alias (__libc_##name, name);
 775 #endif /* !HAVE_GCC_IFUNC  */
 776
 777 /* The following macros are used for indirect function symbols in libc.so.
 778    First of all, you need to have the function prototyped somewhere,
 779    say in foo.h:
 780
 781    int foo (int __bar);
 782
 783    If you have an implementation for foo which e.g. uses a special hardware
 784    feature which isn't available on all machines where this libc.so will be
 785    used but decideable if available at runtime e.g. via hwcaps, you can provide
 786    two or multiple implementations of foo:
 787
 788    int __foo_default (int __bar)
 789    {
 790      return __bar;
 791    }
 792
 793    int __foo_special (int __bar)
 794    {
 795      return __bar;
 796    }
 797
 798    If your function foo has no libc_hidden_proto (foo) defined for PLT
 799    bypassing, you can use:
 800
 801    #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
 802
 803    libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
 804
 805    This will define a resolver function for foo which returns __foo_special or
 806    __foo_default depending on your specified expression.  Please note that you
 807    have to define a macro function INIT_ARCH before using libc_ifunc macro as
 808    it is called by the resolver function before evaluating the specified
 809    expression.  In this example it is used to prepare the hwcap variable.
 810    The resolver function is assigned to an ifunc'ed symbol foo.  Calls to foo
 811    from inside or outside of libc.so will be indirected by a PLT call.
 812
 813    If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
 814    and calls to foo within libc.so should always go to one specific
 815    implementation of foo e.g. __foo_default then you have to add:
 816
 817    __hidden_ver1 (__foo_default, __GI_foo, __foo_default);
 818
 819    or a tweaked definition of libc_hidden_def macro after the __foo_default
 820    function definition.  Calls to foo within libc.so will always go directly to
 821    __foo_default.  Calls to foo from outside libc.so will be indirected by a
 822    PLT call to ifunc'ed symbol foo which you have to define in a separate
 823    compile unit:
 824
 825    #define foo __redirect_foo
 826    #include <foo.h>
 827    #undef foo
 828
 829    extern __typeof (__redirect_foo) __foo_default attribute_hidden;
 830    extern __typeof (__redirect_foo) __foo_special attribute_hidden;
 831
 832    libc_ifunc_redirected (__redirect_foo, foo,
 833                           (hwcap & HWCAP_SPECIAL)
 834                           ? __foo_special
 835                           : __foo_default);
 836
 837    This will define the ifunc'ed symbol foo like above.  The redirection of foo
 838    in header file is needed to omit an additional defintion of __GI_foo which
 839    would end in a linker error while linking libc.so.  You have to specify
 840    __redirect_foo as first parameter which is used within libc_ifunc_redirected
 841    macro in conjunction with typeof to define the ifunc'ed symbol foo.
 842
 843    If your function foo has a libc_hidden_proto (foo) defined and calls to foo
 844    within or from outside libc.so should go via ifunc'ed symbol, then you have
 845    to use:
 846
 847    libc_ifunc_hidden (foo, foo,
 848                       (hwcap & HWCAP_SPECIAL)
 849                       ? __foo_special
 850                       : __foo_default);
 851    libc_hidden_def (foo)
 852
 853    The first parameter foo of libc_ifunc_hidden macro is used in the same way
 854    as for libc_ifunc_redirected macro.  */
 855
 856 #define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
 857
 858 #define libc_ifunc_redirected(redirected_name, name, expr)      \
 859   __ifunc (redirected_name, name, expr, void, INIT_ARCH)
 860
 861 #define libc_ifunc_hidden(redirected_name, name, expr)                  \
 862   __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
 863
 864 /* The body of the function is supposed to use __get_cpu_features
 865    which will, if necessary, initialize the data first.  */
 866 #define libm_ifunc_init()
 867 #define libm_ifunc(name, expr)                          \
 868   __ifunc (name, name, expr, void, libm_ifunc_init)
 869
 870 /* Add the compiler optimization to inhibit loop transformation to library
 871    calls.  This is used to avoid recursive calls in memset and memmove
 872    default implementations.  */
 873 #ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
 874 # define inhibit_loop_to_libcall \
 875     __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
 876 #else
 877 # define inhibit_loop_to_libcall
 878 #endif
 879
 880 #endif /* libc-symbols.h */