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 /* And we also need the data for the reentrant functions.  */
  56 #define _REENTRANT      1
  57
  58 #include <config.h>
  59
  60 /* Define this for the benefit of portable GNU code that wants to check it.
  61    Code that checks with #if will not #include <config.h> again, since we've
  62    already done it (and this file is implicitly included in every compile,
  63    via -include).  Code that checks with #ifdef will #include <config.h>,
  64    but that file should always be idempotent (i.e., it's just #define/#undef
  65    and nothing else anywhere should be changing the macro state it touches),
  66    so it's harmless.  */
  67 #define HAVE_CONFIG_H   0
  68
  69 /* Define these macros for the benefit of portable GNU code that wants to check
  70    them.  Of course, STDC_HEADERS is never false when building libc!  */
  71 #define STDC_HEADERS    1
  72 #define HAVE_MBSTATE_T  1
  73 #define HAVE_MBSRTOWCS  1
  74 #define HAVE_LIBINTL_H  1
  75 #define HAVE_WCTYPE_H   1
  76 #define HAVE_ISWCTYPE   1
  77 #define ENABLE_NLS      1
  78
  79 /* The symbols in all the user (non-_) macros are C symbols.  */
  80
  81 #ifndef __SYMBOL_PREFIX
  82 # define __SYMBOL_PREFIX
  83 #endif
  84
  85 #ifndef C_SYMBOL_NAME
  86 # define C_SYMBOL_NAME(name) name
  87 #endif
  88
  89 #ifndef ASM_LINE_SEP
  90 # define ASM_LINE_SEP ;
  91 #endif
  92
  93 #ifndef __ASSEMBLER__
  94 /* GCC understands weak symbols and aliases; use its interface where
  95    possible, instead of embedded assembly language.  */
  96
  97 /* Define ALIASNAME as a strong alias for NAME.  */
  98 # define strong_alias(name, aliasname) _strong_alias(name, aliasname)
  99 # define _strong_alias(name, aliasname) \
 100   extern __typeof (name) aliasname __attribute__ ((alias (#name)));
 101
 102 /* This comes between the return type and function name in
 103    a function definition to make that definition weak.  */
 104 # define weak_function __attribute__ ((weak))
 105 # define weak_const_function __attribute__ ((weak, __const__))
 106
 107 /* Define ALIASNAME as a weak alias for NAME.
 108    If weak aliases are not available, this defines a strong alias.  */
 109 # define weak_alias(name, aliasname) _weak_alias (name, aliasname)
 110 # define _weak_alias(name, aliasname) \
 111   extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
 112
 113 /* Same as WEAK_ALIAS, but mark symbol as hidden.  */
 114 # define weak_hidden_alias(name, aliasname) \
 115   _weak_hidden_alias (name, aliasname)
 116 # define _weak_hidden_alias(name, aliasname) \
 117   extern __typeof (name) aliasname \
 118     __attribute__ ((weak, alias (#name), __visibility__ ("hidden")));
 119
 120 /* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined).  */
 121 # define weak_extern(symbol) _weak_extern (weak symbol)
 122 # define _weak_extern(expr) _Pragma (#expr)
 123
 124 /* In shared builds, the expression call_function_static_weak
 125    (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
 126    identifier) unconditionally, with the (potentially empty) argument
 127    list ARGUMENTS.  In static builds, if FUNCTION-SYMBOL has a
 128    definition, the function is invoked as before; if FUNCTION-SYMBOL
 129    is NULL, no call is performed.  */
 130 # ifdef SHARED
 131 #  define call_function_static_weak(func, ...) func (__VA_ARGS__)
 132 # else  /* !SHARED */
 133 #  define call_function_static_weak(func, ...)          \
 134   ({                                                    \
 135     extern __typeof__ (func) func weak_function;        \
 136     (func != NULL ? func (__VA_ARGS__) : (void)0);      \
 137   })
 138 # endif
 139
 140 #else /* __ASSEMBLER__ */
 141
 142 # ifdef HAVE_ASM_SET_DIRECTIVE
 143 #  define strong_alias(original, alias)                         \
 144   .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP             \
 145   .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
 146 #  define strong_data_alias(original, alias) strong_alias(original, alias)
 147 # else
 148 #  define strong_alias(original, alias)                         \
 149   .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP             \
 150   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 151 #  define strong_data_alias(original, alias) strong_alias(original, alias)
 152 # endif
 153
 154 # define weak_alias(original, alias)                                    \
 155   .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP                              \
 156   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 157
 158 # define weak_extern(symbol)                                            \
 159   .weak C_SYMBOL_NAME (symbol)
 160
 161 #endif /* __ASSEMBLER__ */
 162
 163 /* On some platforms we can make internal function calls (i.e., calls of
 164    functions not exported) a bit faster by using a different calling
 165    convention.  */
 166 #ifndef internal_function
 167 # define internal_function      /* empty */
 168 #endif
 169
 170 /* Determine the return address.  */
 171 #define RETURN_ADDRESS(nr) \
 172   __builtin_extract_return_addr (__builtin_return_address (nr))
 173
 174 /* When a reference to SYMBOL is encountered, the linker will emit a
 175    warning message MSG.  */
 176 /* We want the .gnu.warning.SYMBOL section to be unallocated.  */
 177 #define __make_section_unallocated(section_string)      \
 178   asm (".section " section_string "\n\t.previous");
 179
 180 /* Tacking on "\n\t#" to the section name makes gcc put it's bogus
 181    section attributes on what looks like a comment to the assembler.  */
 182 #ifdef HAVE_SECTION_QUOTES
 183 # define __sec_comment "\"\n\t#\""
 184 #else
 185 # define __sec_comment "\n\t#"
 186 #endif
 187 #define link_warning(symbol, msg) \
 188   __make_section_unallocated (".gnu.warning." #symbol) \
 189   static const char __evoke_link_warning_##symbol[]     \
 190     __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
 191     = msg;
 192 #define libc_freeres_ptr(decl) \
 193   __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
 194   decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
 195 #define __libc_freeres_fn_section \
 196   __attribute__ ((section ("__libc_freeres_fn")))
 197
 198 #define libc_freeres_fn(name)   \
 199   static void name (void) __attribute_used__ __libc_freeres_fn_section; \
 200   text_set_element (__libc_subfreeres, name);                           \
 201   static void name (void)
 202
 203 /* A canned warning for sysdeps/stub functions.  */
 204 #define stub_warning(name) \
 205   __make_section_unallocated (".gnu.glibc-stub." #name) \
 206   link_warning (name, #name " is not implemented and will always fail")
 207
 208 /* Warning for linking functions calling dlopen into static binaries.  */
 209 #ifdef SHARED
 210 #define static_link_warning(name)
 211 #else
 212 #define static_link_warning(name) static_link_warning1(name)
 213 #define static_link_warning1(name) \
 214   link_warning(name, "Using '" #name "' in statically linked applications \
 215 requires at runtime the shared libraries from the glibc version used \
 216 for linking")
 217 #endif
 218
 219 /* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
 220    alias to ORIGINAL, when the assembler supports such declarations
 221    (such as in ELF).
 222    This is only necessary when defining something in assembly, or playing
 223    funny alias games where the size should be other than what the compiler
 224    thinks it is.  */
 225 #define declare_symbol_alias(symbol, original, type, size) \
 226   declare_symbol_alias_1 (symbol, original, type, size)
 227 #ifdef __ASSEMBLER__
 228 # define declare_symbol_alias_1(symbol, original, type, size) \
 229    strong_alias (original, symbol); \
 230    .type C_SYMBOL_NAME (symbol), %##type; \
 231    .size C_SYMBOL_NAME (symbol), size
 232 #else /* Not __ASSEMBLER__.  */
 233 # define declare_symbol_alias_1(symbol, original, type, size) \
 234    asm (".globl " __SYMBOL_PREFIX #symbol \
 235         "\n\t" declare_symbol_alias_1_alias (symbol, original) \
 236         "\n\t.type " __SYMBOL_PREFIX #symbol ", " \
 237         "%" #type \
 238         "\n\t.size " __SYMBOL_PREFIX #symbol ", " #size);
 239 # ifdef HAVE_ASM_SET_DIRECTIVE
 240 #  define declare_symbol_alias_1_alias(symbol, original) \
 241      ".set " __SYMBOL_PREFIX #symbol ", " __SYMBOL_PREFIX #original
 242 # else
 243 #  define declare_symbol_alias_1_alias(symbol, original) \
 244      __SYMBOL_PREFIX #symbol " = " __SYMBOL_PREFIX #original
 245 # endif /* HAVE_ASM_SET_DIRECTIVE */
 246 #endif /* __ASSEMBLER__ */
 247
 248
 249 /*
 250 \f
 251 */
 252
 253 /* Symbol set support macros.  */
 254
 255 /* Make SYMBOL, which is in the text segment, an element of SET.  */
 256 #define text_set_element(set, symbol)   _elf_set_element(set, symbol)
 257 /* Make SYMBOL, which is in the data segment, an element of SET.  */
 258 #define data_set_element(set, symbol)   _elf_set_element(set, symbol)
 259 /* Make SYMBOL, which is in the bss segment, an element of SET.  */
 260 #define bss_set_element(set, symbol)    _elf_set_element(set, symbol)
 261
 262 /* These are all done the same way in ELF.
 263    There is a new section created for each set.  */
 264 #ifdef SHARED
 265 /* When building a shared library, make the set section writable,
 266    because it will need to be relocated at run time anyway.  */
 267 # define _elf_set_element(set, symbol) \
 268   static const void *__elf_set_##set##_element_##symbol##__ \
 269     __attribute__ ((used, section (#set))) = &(symbol)
 270 #else
 271 # define _elf_set_element(set, symbol) \
 272   static const void *const __elf_set_##set##_element_##symbol##__ \
 273     __attribute__ ((used, section (#set))) = &(symbol)
 274 #endif
 275
 276 /* Define SET as a symbol set.  This may be required (it is in a.out) to
 277    be able to use the set's contents.  */
 278 #define symbol_set_define(set)  symbol_set_declare(set)
 279
 280 /* Declare SET for use in this module, if defined in another module.
 281    In a shared library, this is always local to that shared object.
 282    For static linking, the set might be wholly absent and so we use
 283    weak references.  */
 284 #define symbol_set_declare(set) \
 285   extern char const __start_##set[] __symbol_set_attribute; \
 286   extern char const __stop_##set[] __symbol_set_attribute;
 287 #ifdef SHARED
 288 # define __symbol_set_attribute attribute_hidden
 289 #else
 290 # define __symbol_set_attribute __attribute__ ((weak))
 291 #endif
 292
 293 /* Return a pointer (void *const *) to the first element of SET.  */
 294 #define symbol_set_first_element(set)   ((void *const *) (&__start_##set))
 295
 296 /* Return true iff PTR (a void *const *) has been incremented
 297    past the last element in SET.  */
 298 #define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
 299
 300 /* Use symbol_version_reference to specify the version a symbol
 301    reference should link to.  Use symbol_version or
 302    default_symbol_version for the definition of a versioned symbol.
 303    The difference is that the latter is a no-op in non-shared
 304    builds.  */
 305 #ifdef __ASSEMBLER__
 306 # define symbol_version_reference(real, name, version) \
 307      .symver real, name##@##version
 308 #else  /* !__ASSEMBLER__ */
 309 # define symbol_version_reference(real, name, version) \
 310   __asm__ (".symver " #real "," #name "@" #version)
 311 #endif
 312
 313 #ifdef SHARED
 314 # define symbol_version(real, name, version) \
 315   symbol_version_reference(real, name, version)
 316 # define default_symbol_version(real, name, version) \
 317      _default_symbol_version(real, name, version)
 318 # ifdef __ASSEMBLER__
 319 #  define _default_symbol_version(real, name, version) \
 320      .symver real, name##@##@##version
 321 # else
 322 #  define _default_symbol_version(real, name, version) \
 323      __asm__ (".symver " #real "," #name "@@" #version)
 324 # endif
 325 #else
 326 # define symbol_version(real, name, version)
 327 # define default_symbol_version(real, name, version) \
 328   strong_alias(real, name)
 329 #endif
 330
 331 #if defined SHARED || defined LIBC_NONSHARED
 332 # define attribute_hidden __attribute__ ((visibility ("hidden")))
 333 #else
 334 # define attribute_hidden
 335 #endif
 336
 337 #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
 338
 339 #define attribute_relro __attribute__ ((section (".data.rel.ro")))
 340
 341 /* The following macros are used for PLT bypassing within libc.so
 342    (and if needed other libraries similarly).
 343    First of all, you need to have the function prototyped somewhere,
 344    say in foo/foo.h:
 345
 346    int foo (int __bar);
 347
 348    If calls to foo within libc.so should always go to foo defined in libc.so,
 349    then in include/foo.h you add:
 350
 351    libc_hidden_proto (foo)
 352
 353    line and after the foo function definition:
 354
 355    int foo (int __bar)
 356    {
 357      return __bar;
 358    }
 359    libc_hidden_def (foo)
 360
 361    or
 362
 363    int foo (int __bar)
 364    {
 365      return __bar;
 366    }
 367    libc_hidden_weak (foo)
 368
 369    Similarly for global data.  If references to foo within libc.so should
 370    always go to foo defined in libc.so, then in include/foo.h you add:
 371
 372    libc_hidden_proto (foo)
 373
 374    line and after foo's definition:
 375
 376    int foo = INITIAL_FOO_VALUE;
 377    libc_hidden_data_def (foo)
 378
 379    or
 380
 381    int foo = INITIAL_FOO_VALUE;
 382    libc_hidden_data_weak (foo)
 383
 384    If foo is normally just an alias (strong or weak) to some other function,
 385    you should use the normal strong_alias first, then add libc_hidden_def
 386    or libc_hidden_weak:
 387
 388    int baz (int __bar)
 389    {
 390      return __bar;
 391    }
 392    strong_alias (baz, foo)
 393    libc_hidden_weak (foo)
 394
 395    If the function should be internal to multiple objects, say ld.so and
 396    libc.so, the best way is to use:
 397
 398    #if IS_IN (libc) || IS_IN (rtld)
 399    hidden_proto (foo)
 400    #endif
 401
 402    in include/foo.h and the normal macros at all function definitions
 403    depending on what DSO they belong to.
 404
 405    If versioned_symbol macro is used to define foo,
 406    libc_hidden_ver macro should be used, as in:
 407
 408    int __real_foo (int __bar)
 409    {
 410      return __bar;
 411    }
 412    versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
 413    libc_hidden_ver (__real_foo, foo)  */
 414
 415 #if defined SHARED && !defined NO_HIDDEN
 416 # ifndef __ASSEMBLER__
 417 #  define __hidden_proto_hiddenattr(attrs...) \
 418   __attribute__ ((visibility ("hidden"), ##attrs))
 419 #  define hidden_proto(name, attrs...) \
 420   __hidden_proto (name, , __GI_##name, ##attrs)
 421 #  define hidden_tls_proto(name, attrs...) \
 422   __hidden_proto (name, __thread, __GI_##name, ##attrs)
 423 #  define __hidden_proto(name, thread, internal, attrs...)           \
 424   extern thread __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
 425   __hidden_proto_hiddenattr (attrs);
 426 #  define __hidden_asmname(name) \
 427   __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
 428 #  define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
 429 #  define __hidden_asmname2(prefix, name) #prefix name
 430 #  define __hidden_ver1(local, internal, name) \
 431   extern __typeof (name) __EI_##name __asm__(__hidden_asmname (#internal)); \
 432   extern __typeof (name) __EI_##name \
 433         __attribute__((alias (__hidden_asmname (#local))))
 434 #  define hidden_ver(local, name)       __hidden_ver1(local, __GI_##name, name);
 435 #  define hidden_data_ver(local, name)  hidden_ver(local, name)
 436 #  define hidden_def(name)              __hidden_ver1(__GI_##name, name, name);
 437 #  define hidden_data_def(name)         hidden_def(name)
 438 #  define hidden_weak(name) \
 439         __hidden_ver1(__GI_##name, name, name) __attribute__((weak));
 440 #  define hidden_data_weak(name)        hidden_weak(name)
 441 #  define hidden_nolink(name, lib, version) \
 442   __hidden_nolink1 (__GI_##name, __EI_##name, name, VERSION_##lib##_##version)
 443 #  define __hidden_nolink1(local, internal, name, version) \
 444   __hidden_nolink2 (local, internal, name, version)
 445 #  define __hidden_nolink2(local, internal, name, version) \
 446   extern __typeof (name) internal __attribute__ ((alias (#local))); \
 447   __hidden_nolink3 (local, internal, #name "@" #version)
 448 #  define __hidden_nolink3(local, internal, vername) \
 449   __asm__ (".symver " #internal ", " vername);
 450 # else
 451 /* For assembly, we need to do the opposite of what we do in C:
 452    in assembly gcc __REDIRECT stuff is not in place, so functions
 453    are defined by its normal name and we need to create the
 454    __GI_* alias to it, in C __REDIRECT causes the function definition
 455    to use __GI_* name and we need to add alias to the real name.
 456    There is no reason to use hidden_weak over hidden_def in assembly,
 457    but we provide it for consistency with the C usage.
 458    hidden_proto doesn't make sense for assembly but the equivalent
 459    is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET.  */
 460 #  define hidden_def(name)      strong_alias (name, __GI_##name)
 461 #  define hidden_weak(name)     hidden_def (name)
 462 #  define hidden_ver(local, name) strong_alias (local, __GI_##name)
 463 #  define hidden_data_def(name) strong_data_alias (name, __GI_##name)
 464 #  define hidden_data_weak(name)        hidden_data_def (name)
 465 #  define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
 466 #  define HIDDEN_JUMPTARGET(name) __GI_##name
 467 # endif
 468 #else
 469 # ifndef __ASSEMBLER__
 470 #  define hidden_proto(name, attrs...)
 471 #  define hidden_tls_proto(name, attrs...)
 472 # else
 473 #  define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
 474 # endif /* Not  __ASSEMBLER__ */
 475 # define hidden_weak(name)
 476 # define hidden_def(name)
 477 # define hidden_ver(local, name)
 478 # define hidden_data_weak(name)
 479 # define hidden_data_def(name)
 480 # define hidden_data_ver(local, name)
 481 # define hidden_nolink(name, lib, version)
 482 #endif
 483
 484 #if IS_IN (libc)
 485 # define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 486 # define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 487 # define libc_hidden_def(name) hidden_def (name)
 488 # define libc_hidden_weak(name) hidden_weak (name)
 489 # ifdef LINK_OBSOLETE_RPC
 490    /* libc_hidden_nolink_sunrpc should only get used in sunrpc code.  */
 491 #  define libc_hidden_nolink_sunrpc(name, version) hidden_def (name)
 492 # else
 493 #  define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
 494 # endif
 495 # define libc_hidden_ver(local, name) hidden_ver (local, name)
 496 # define libc_hidden_data_def(name) hidden_data_def (name)
 497 # define libc_hidden_data_weak(name) hidden_data_weak (name)
 498 # define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
 499 #else
 500 # define libc_hidden_proto(name, attrs...)
 501 # define libc_hidden_tls_proto(name, attrs...)
 502 # define libc_hidden_def(name)
 503 # define libc_hidden_weak(name)
 504 # define libc_hidden_ver(local, name)
 505 # define libc_hidden_data_def(name)
 506 # define libc_hidden_data_weak(name)
 507 # define libc_hidden_data_ver(local, name)
 508 #endif
 509
 510 #if IS_IN (rtld)
 511 # define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 512 # define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 513 # define rtld_hidden_def(name) hidden_def (name)
 514 # define rtld_hidden_weak(name) hidden_weak (name)
 515 # define rtld_hidden_ver(local, name) hidden_ver (local, name)
 516 # define rtld_hidden_data_def(name) hidden_data_def (name)
 517 # define rtld_hidden_data_weak(name) hidden_data_weak (name)
 518 # define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
 519 #else
 520 # define rtld_hidden_proto(name, attrs...)
 521 # define rtld_hidden_tls_proto(name, attrs...)
 522 # define rtld_hidden_def(name)
 523 # define rtld_hidden_weak(name)
 524 # define rtld_hidden_ver(local, name)
 525 # define rtld_hidden_data_def(name)
 526 # define rtld_hidden_data_weak(name)
 527 # define rtld_hidden_data_ver(local, name)
 528 #endif
 529
 530 #if IS_IN (libm)
 531 # define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 532 # define libm_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 533 # define libm_hidden_def(name) hidden_def (name)
 534 # define libm_hidden_weak(name) hidden_weak (name)
 535 # define libm_hidden_ver(local, name) hidden_ver (local, name)
 536 # define libm_hidden_data_def(name) hidden_data_def (name)
 537 # define libm_hidden_data_weak(name) hidden_data_weak (name)
 538 # define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
 539 #else
 540 # define libm_hidden_proto(name, attrs...)
 541 # define libm_hidden_tls_proto(name, attrs...)
 542 # define libm_hidden_def(name)
 543 # define libm_hidden_weak(name)
 544 # define libm_hidden_ver(local, name)
 545 # define libm_hidden_data_def(name)
 546 # define libm_hidden_data_weak(name)
 547 # define libm_hidden_data_ver(local, name)
 548 #endif
 549
 550 #if IS_IN (libmvec)
 551 # define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 552 # define libmvec_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 553 # define libmvec_hidden_def(name) hidden_def (name)
 554 # define libmvec_hidden_weak(name) hidden_weak (name)
 555 # define libmvec_hidden_ver(local, name) hidden_ver (local, name)
 556 # define libmvec_hidden_data_def(name) hidden_data_def (name)
 557 # define libmvec_hidden_data_weak(name) hidden_data_weak (name)
 558 # define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
 559 #else
 560 # define libmvec_hidden_proto(name, attrs...)
 561 # define libmvec_hidden_tls_proto(name, attrs...)
 562 # define libmvec_hidden_def(name)
 563 # define libmvec_hidden_weak(name)
 564 # define libmvec_hidden_ver(local, name)
 565 # define libmvec_hidden_data_def(name)
 566 # define libmvec_hidden_data_weak(name)
 567 # define libmvec_hidden_data_ver(local, name)
 568 #endif
 569
 570 #if IS_IN (libresolv)
 571 # define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 572 # define libresolv_hidden_tls_proto(name, attrs...) \
 573   hidden_tls_proto (name, ##attrs)
 574 # define libresolv_hidden_def(name) hidden_def (name)
 575 # define libresolv_hidden_weak(name) hidden_weak (name)
 576 # define libresolv_hidden_ver(local, name) hidden_ver (local, name)
 577 # define libresolv_hidden_data_def(name) hidden_data_def (name)
 578 # define libresolv_hidden_data_weak(name) hidden_data_weak (name)
 579 # define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
 580 #else
 581 # define libresolv_hidden_proto(name, attrs...)
 582 # define libresolv_hidden_tls_proto(name, attrs...)
 583 # define libresolv_hidden_def(name)
 584 # define libresolv_hidden_weak(name)
 585 # define libresolv_hidden_ver(local, name)
 586 # define libresolv_hidden_data_def(name)
 587 # define libresolv_hidden_data_weak(name)
 588 # define libresolv_hidden_data_ver(local, name)
 589 #endif
 590
 591 #if IS_IN (librt)
 592 # define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 593 # define librt_hidden_tls_proto(name, attrs...) \
 594   hidden_tls_proto (name, ##attrs)
 595 # define librt_hidden_def(name) hidden_def (name)
 596 # define librt_hidden_weak(name) hidden_weak (name)
 597 # define librt_hidden_ver(local, name) hidden_ver (local, name)
 598 # define librt_hidden_data_def(name) hidden_data_def (name)
 599 # define librt_hidden_data_weak(name) hidden_data_weak (name)
 600 # define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
 601 #else
 602 # define librt_hidden_proto(name, attrs...)
 603 # define librt_hidden_tls_proto(name, attrs...)
 604 # define librt_hidden_def(name)
 605 # define librt_hidden_weak(name)
 606 # define librt_hidden_ver(local, name)
 607 # define librt_hidden_data_def(name)
 608 # define librt_hidden_data_weak(name)
 609 # define librt_hidden_data_ver(local, name)
 610 #endif
 611
 612 #if IS_IN (libdl)
 613 # define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 614 # define libdl_hidden_tls_proto(name, attrs...) \
 615   hidden_tls_proto (name, ##attrs)
 616 # define libdl_hidden_def(name) hidden_def (name)
 617 # define libdl_hidden_weak(name) hidden_weak (name)
 618 # define libdl_hidden_ver(local, name) hidden_ver (local, name)
 619 # define libdl_hidden_data_def(name) hidden_data_def (name)
 620 # define libdl_hidden_data_weak(name) hidden_data_weak (name)
 621 # define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
 622 #else
 623 # define libdl_hidden_proto(name, attrs...)
 624 # define libdl_hidden_tls_proto(name, attrs...)
 625 # define libdl_hidden_def(name)
 626 # define libdl_hidden_weak(name)
 627 # define libdl_hidden_ver(local, name)
 628 # define libdl_hidden_data_def(name)
 629 # define libdl_hidden_data_weak(name)
 630 # define libdl_hidden_data_ver(local, name)
 631 #endif
 632
 633 #if IS_IN (libnss_files)
 634 # define libnss_files_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 635 # define libnss_files_hidden_tls_proto(name, attrs...) \
 636   hidden_tls_proto (name, ##attrs)
 637 # define libnss_files_hidden_def(name) hidden_def (name)
 638 # define libnss_files_hidden_weak(name) hidden_weak (name)
 639 # define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
 640 # define libnss_files_hidden_data_def(name) hidden_data_def (name)
 641 # define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
 642 # define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
 643 #else
 644 # define libnss_files_hidden_proto(name, attrs...)
 645 # define libnss_files_hidden_tls_proto(name, attrs...)
 646 # define libnss_files_hidden_def(name)
 647 # define libnss_files_hidden_weak(name)
 648 # define libnss_files_hidden_ver(local, name)
 649 # define libnss_files_hidden_data_def(name)
 650 # define libnss_files_hidden_data_weak(name)
 651 # define libnss_files_hidden_data_ver(local, name)
 652 #endif
 653
 654 #if IS_IN (libnsl)
 655 # define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 656 # define libnsl_hidden_tls_proto(name, attrs...) \
 657   hidden_tls_proto (name, ##attrs)
 658 # define libnsl_hidden_def(name) hidden_def (name)
 659 # define libnsl_hidden_weak(name) hidden_weak (name)
 660 # define libnsl_hidden_ver(local, name) hidden_ver (local, name)
 661 # define libnsl_hidden_data_def(name) hidden_data_def (name)
 662 # define libnsl_hidden_data_weak(name) hidden_data_weak (name)
 663 # define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
 664 #else
 665 # define libnsl_hidden_proto(name, attrs...)
 666 # define libnsl_hidden_tls_proto(name, attrs...)
 667 # define libnsl_hidden_def(name)
 668 # define libnsl_hidden_weak(name)
 669 # define libnsl_hidden_ver(local, name)
 670 # define libnsl_hidden_data_def(name)
 671 # define libnsl_hidden_data_weak(name)
 672 # define libnsl_hidden_data_ver(local, name)
 673 #endif
 674
 675 #if IS_IN (libnss_nisplus)
 676 # define libnss_nisplus_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 677 # define libnss_nisplus_hidden_tls_proto(name, attrs...) \
 678   hidden_tls_proto (name, ##attrs)
 679 # define libnss_nisplus_hidden_def(name) hidden_def (name)
 680 # define libnss_nisplus_hidden_weak(name) hidden_weak (name)
 681 # define libnss_nisplus_hidden_ver(local, name) hidden_ver (local, name)
 682 # define libnss_nisplus_hidden_data_def(name) hidden_data_def (name)
 683 # define libnss_nisplus_hidden_data_weak(name) hidden_data_weak (name)
 684 # define libnss_nisplus_hidden_data_ver(local, name) hidden_data_ver (local, name)
 685 #else
 686 # define libnss_nisplus_hidden_proto(name, attrs...)
 687 # define libnss_nisplus_hidden_tls_proto(name, attrs...)
 688 # define libnss_nisplus_hidden_def(name)
 689 # define libnss_nisplus_hidden_weak(name)
 690 # define libnss_nisplus_hidden_ver(local, name)
 691 # define libnss_nisplus_hidden_data_def(name)
 692 # define libnss_nisplus_hidden_data_weak(name)
 693 # define libnss_nisplus_hidden_data_ver(local, name)
 694 #endif
 695
 696 #define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
 697 #define libc_hidden_builtin_def(name) libc_hidden_def (name)
 698 #define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
 699 #define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
 700 #ifdef __ASSEMBLER__
 701 # define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
 702 #endif
 703
 704 #if IS_IN (libutil)
 705 # define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 706 # define libutil_hidden_tls_proto(name, attrs...) \
 707   hidden_tls_proto (name, ##attrs)
 708 # define libutil_hidden_def(name) hidden_def (name)
 709 # define libutil_hidden_weak(name) hidden_weak (name)
 710 # define libutil_hidden_ver(local, name) hidden_ver (local, name)
 711 # define libutil_hidden_data_def(name) hidden_data_def (name)
 712 # define libutil_hidden_data_weak(name) hidden_data_weak (name)
 713 # define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
 714 #else
 715 # define libutil_hidden_proto(name, attrs...)
 716 # define libutil_hidden_tls_proto(name, attrs...)
 717 # define libutil_hidden_def(name)
 718 # define libutil_hidden_weak(name)
 719 # define libutil_hidden_ver(local, name)
 720 # define libutil_hidden_data_def(name)
 721 # define libutil_hidden_data_weak(name)
 722 # define libutil_hidden_data_ver(local, name)
 723 #endif
 724
 725 /* Get some dirty hacks.  */
 726 #include <symbol-hacks.h>
 727
 728 /* Move compatibility symbols out of the way by placing them all in a
 729    special section.  */
 730 #ifndef __ASSEMBLER__
 731 # define attribute_compat_text_section \
 732     __attribute__ ((section (".text.compat")))
 733 # define attribute_compat_data_section \
 734     __attribute__ ((section (".data.compat")))
 735 #else
 736 # define compat_text_section .section ".text.compat", "ax";
 737 # define compat_data_section .section ".data.compat", "aw";
 738 #endif
 739
 740 /* Helper / base  macros for indirect function symbols.  */
 741 #define __ifunc_resolver(type_name, name, expr, arg, init, classifier)  \
 742   classifier void *name##_ifunc (arg)                                   \
 743   {                                                                     \
 744     init ();                                                            \
 745     __typeof (type_name) *res = expr;                                   \
 746     return res;                                                         \
 747   }
 748
 749 #ifdef HAVE_GCC_IFUNC
 750 # define __ifunc(type_name, name, expr, arg, init)                      \
 751   extern __typeof (type_name) name __attribute__                        \
 752                               ((ifunc (#name "_ifunc")));               \
 753   __ifunc_resolver (type_name, name, expr, arg, init, static)
 754
 755 # define __ifunc_hidden(type_name, name, expr, arg, init)       \
 756   __ifunc (type_name, name, expr, arg, init)
 757 #else
 758 /* Gcc does not support __attribute__ ((ifunc (...))).  Use the old behaviour
 759    as fallback.  But keep in mind that the debug information for the ifunc
 760    resolver functions is not correct.  It contains the ifunc'ed function as
 761    DW_AT_linkage_name.  E.g. lldb uses this field and an inferior function
 762    call of the ifunc'ed function will fail due to "no matching function for
 763    call to ..." because the ifunc'ed function and the resolver function have
 764    different signatures.  (Gcc support is disabled at least on a ppc64le
 765    Ubuntu 14.04 system.)  */
 766
 767 # define __ifunc(type_name, name, expr, arg, init)                      \
 768   extern __typeof (type_name) name;                                     \
 769   void *name##_ifunc (arg) __asm__ (#name);                             \
 770   __ifunc_resolver (type_name, name, expr, arg, init,)                  \
 771  __asm__ (".type " #name ", %gnu_indirect_function");
 772
 773 # define __ifunc_hidden(type_name, name, expr, arg, init)               \
 774   extern __typeof (type_name) __libc_##name;                            \
 775   __ifunc (type_name, __libc_##name, expr, arg, init)                   \
 776   strong_alias (__libc_##name, name);
 777 #endif /* !HAVE_GCC_IFUNC  */
 778
 779 /* The following macros are used for indirect function symbols in libc.so.
 780    First of all, you need to have the function prototyped somewhere,
 781    say in foo.h:
 782
 783    int foo (int __bar);
 784
 785    If you have an implementation for foo which e.g. uses a special hardware
 786    feature which isn't available on all machines where this libc.so will be
 787    used but decideable if available at runtime e.g. via hwcaps, you can provide
 788    two or multiple implementations of foo:
 789
 790    int __foo_default (int __bar)
 791    {
 792      return __bar;
 793    }
 794
 795    int __foo_special (int __bar)
 796    {
 797      return __bar;
 798    }
 799
 800    If your function foo has no libc_hidden_proto (foo) defined for PLT
 801    bypassing, you can use:
 802
 803    #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
 804
 805    libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
 806
 807    This will define a resolver function for foo which returns __foo_special or
 808    __foo_default depending on your specified expression.  Please note that you
 809    have to define a macro function INIT_ARCH before using libc_ifunc macro as
 810    it is called by the resolver function before evaluating the specified
 811    expression.  In this example it is used to prepare the hwcap variable.
 812    The resolver function is assigned to an ifunc'ed symbol foo.  Calls to foo
 813    from inside or outside of libc.so will be indirected by a PLT call.
 814
 815    If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
 816    and calls to foo within libc.so should always go to one specific
 817    implementation of foo e.g. __foo_default then you have to add:
 818
 819    __hidden_ver1 (__foo_default, __GI_foo, __foo_default);
 820
 821    or a tweaked definition of libc_hidden_def macro after the __foo_default
 822    function definition.  Calls to foo within libc.so will always go directly to
 823    __foo_default.  Calls to foo from outside libc.so will be indirected by a
 824    PLT call to ifunc'ed symbol foo which you have to define in a separate
 825    compile unit:
 826
 827    #define foo __redirect_foo
 828    #include <foo.h>
 829    #undef foo
 830
 831    extern __typeof (__redirect_foo) __foo_default attribute_hidden;
 832    extern __typeof (__redirect_foo) __foo_special attribute_hidden;
 833
 834    libc_ifunc_redirected (__redirect_foo, foo,
 835                           (hwcap & HWCAP_SPECIAL)
 836                           ? __foo_special
 837                           : __foo_default);
 838
 839    This will define the ifunc'ed symbol foo like above.  The redirection of foo
 840    in header file is needed to omit an additional defintion of __GI_foo which
 841    would end in a linker error while linking libc.so.  You have to specify
 842    __redirect_foo as first parameter which is used within libc_ifunc_redirected
 843    macro in conjunction with typeof to define the ifunc'ed symbol foo.
 844
 845    If your function foo has a libc_hidden_proto (foo) defined and calls to foo
 846    within or from outside libc.so should go via ifunc'ed symbol, then you have
 847    to use:
 848
 849    libc_ifunc_hidden (foo, foo,
 850                       (hwcap & HWCAP_SPECIAL)
 851                       ? __foo_special
 852                       : __foo_default);
 853    libc_hidden_def (foo)
 854
 855    The first parameter foo of libc_ifunc_hidden macro is used in the same way
 856    as for libc_ifunc_redirected macro.  */
 857
 858 #define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
 859
 860 #define libc_ifunc_redirected(redirected_name, name, expr)      \
 861   __ifunc (redirected_name, name, expr, void, INIT_ARCH)
 862
 863 #define libc_ifunc_hidden(redirected_name, name, expr)                  \
 864   __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
 865
 866 /* The body of the function is supposed to use __get_cpu_features
 867    which will, if necessary, initialize the data first.  */
 868 #define libm_ifunc_init()
 869 #define libm_ifunc(name, expr)                          \
 870   __ifunc (name, name, expr, void, libm_ifunc_init)
 871
 872 #ifdef HAVE_ASM_SET_DIRECTIVE
 873 # define libc_ifunc_hidden_def1(local, name)                            \
 874     __asm__ (".globl " #local "\n\t"                                    \
 875              ".hidden " #local "\n\t"                                   \
 876              ".set " #local ", " #name);
 877 #else
 878 # define libc_ifunc_hidden_def1(local, name)                            \
 879     __asm__ (".globl " #local "\n\t"                                    \
 880              ".hidden " #local "\n\t"                                   \
 881              #local " = " #name);
 882 #endif
 883
 884 #define libc_ifunc_hidden_def(name) \
 885   libc_ifunc_hidden_def1 (__GI_##name, name)
 886
 887 /* Add the compiler optimization to inhibit loop transformation to library
 888    calls.  This is used to avoid recursive calls in memset and memmove
 889    default implementations.  */
 890 #ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
 891 # define inhibit_loop_to_libcall \
 892     __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
 893 #else
 894 # define inhibit_loop_to_libcall
 895 #endif
 896
 897 #endif /* libc-symbols.h */