mirror of
https://sourceware.org/git/glibc.git
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de6591238b
When dynamically linking, ifunc resolvers are called before TLS is
initialized, so they cannot be safely stack-protected.
We avoid disabling stack-protection on large numbers of files by
using __attribute__ ((__optimize__ ("-fno-stack-protector")))
to turn it off just for the resolvers themselves. (We provide
the attribute even when statically linking, because we will later
use it elsewhere too.)
891 lines
34 KiB
C
891 lines
34 KiB
C
/* Support macros for making weak and strong aliases for symbols,
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and for using symbol sets and linker warnings with GNU ld.
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Copyright (C) 1995-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _LIBC_SYMBOLS_H
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#define _LIBC_SYMBOLS_H 1
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#define IN_MODULE PASTE_NAME (MODULE_, MODULE_NAME)
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#define IS_IN(lib) (IN_MODULE == MODULE_##lib)
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/* Returns true if the current module is a versioned library. Versioned
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library names culled from shlib-versions files are assigned a MODULE_*
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value lower than MODULE_LIBS_BEGIN. */
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#define IS_IN_LIB (IN_MODULE > MODULE_LIBS_BEGIN)
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#define PASTE_NAME(a,b) PASTE_NAME1 (a,b)
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#define PASTE_NAME1(a,b) a##b
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/* This file's macros are included implicitly in the compilation of every
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file in the C library by -imacros.
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We include config.h which is generated by configure.
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It should define for us the following symbol:
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* HAVE_ASM_SET_DIRECTIVE if we have `.set B, A' instead of `A = B'.
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*/
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/* This is defined for the compilation of all C library code. features.h
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tests this to avoid inclusion of stubs.h while compiling the library,
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before stubs.h has been generated. Some library code that is shared
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with other packages also tests this symbol to see if it is being
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compiled as part of the C library. We must define this before including
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config.h, because it makes some definitions conditional on whether libc
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itself is being compiled, or just some generator program. */
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#define _LIBC 1
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/* Enable declarations of GNU extensions, since we are compiling them. */
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#define _GNU_SOURCE 1
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#include <config.h>
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/* Define this for the benefit of portable GNU code that wants to check it.
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Code that checks with #if will not #include <config.h> again, since we've
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already done it (and this file is implicitly included in every compile,
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via -include). Code that checks with #ifdef will #include <config.h>,
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but that file should always be idempotent (i.e., it's just #define/#undef
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and nothing else anywhere should be changing the macro state it touches),
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so it's harmless. */
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#define HAVE_CONFIG_H 0
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/* Define these macros for the benefit of portable GNU code that wants to check
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them. Of course, STDC_HEADERS is never false when building libc! */
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#define STDC_HEADERS 1
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#define HAVE_MBSTATE_T 1
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#define HAVE_MBSRTOWCS 1
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#define HAVE_LIBINTL_H 1
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#define HAVE_WCTYPE_H 1
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#define HAVE_ISWCTYPE 1
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#define ENABLE_NLS 1
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/* The symbols in all the user (non-_) macros are C symbols. */
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#ifndef __SYMBOL_PREFIX
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# define __SYMBOL_PREFIX
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#endif
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#ifndef C_SYMBOL_NAME
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# define C_SYMBOL_NAME(name) name
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#endif
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#ifndef ASM_LINE_SEP
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# define ASM_LINE_SEP ;
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#endif
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#ifndef __ASSEMBLER__
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/* GCC understands weak symbols and aliases; use its interface where
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possible, instead of embedded assembly language. */
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/* Define ALIASNAME as a strong alias for NAME. */
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# define strong_alias(name, aliasname) _strong_alias(name, aliasname)
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# define _strong_alias(name, aliasname) \
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extern __typeof (name) aliasname __attribute__ ((alias (#name)));
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/* This comes between the return type and function name in
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a function definition to make that definition weak. */
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# define weak_function __attribute__ ((weak))
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# define weak_const_function __attribute__ ((weak, __const__))
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/* Define ALIASNAME as a weak alias for NAME.
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If weak aliases are not available, this defines a strong alias. */
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# define weak_alias(name, aliasname) _weak_alias (name, aliasname)
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# define _weak_alias(name, aliasname) \
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extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
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/* Same as WEAK_ALIAS, but mark symbol as hidden. */
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# define weak_hidden_alias(name, aliasname) \
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_weak_hidden_alias (name, aliasname)
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# define _weak_hidden_alias(name, aliasname) \
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extern __typeof (name) aliasname \
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__attribute__ ((weak, alias (#name), __visibility__ ("hidden")));
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/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */
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# define weak_extern(symbol) _weak_extern (weak symbol)
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# define _weak_extern(expr) _Pragma (#expr)
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/* In shared builds, the expression call_function_static_weak
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(FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
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identifier) unconditionally, with the (potentially empty) argument
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list ARGUMENTS. In static builds, if FUNCTION-SYMBOL has a
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definition, the function is invoked as before; if FUNCTION-SYMBOL
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is NULL, no call is performed. */
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# ifdef SHARED
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# define call_function_static_weak(func, ...) func (__VA_ARGS__)
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# else /* !SHARED */
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# define call_function_static_weak(func, ...) \
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({ \
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extern __typeof__ (func) func weak_function; \
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(func != NULL ? func (__VA_ARGS__) : (void)0); \
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})
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# endif
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#else /* __ASSEMBLER__ */
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# ifdef HAVE_ASM_SET_DIRECTIVE
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# define strong_alias(original, alias) \
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.globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
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.set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
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# define strong_data_alias(original, alias) strong_alias(original, alias)
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# else
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# define strong_alias(original, alias) \
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.globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \
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C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
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# define strong_data_alias(original, alias) strong_alias(original, alias)
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# endif
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# define weak_alias(original, alias) \
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.weak C_SYMBOL_NAME (alias) ASM_LINE_SEP \
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C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
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# define weak_extern(symbol) \
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.weak C_SYMBOL_NAME (symbol)
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#endif /* __ASSEMBLER__ */
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/* On some platforms we can make internal function calls (i.e., calls of
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functions not exported) a bit faster by using a different calling
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convention. */
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#ifndef internal_function
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# define internal_function /* empty */
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#endif
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/* Determine the return address. */
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#define RETURN_ADDRESS(nr) \
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__builtin_extract_return_addr (__builtin_return_address (nr))
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/* When a reference to SYMBOL is encountered, the linker will emit a
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warning message MSG. */
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/* We want the .gnu.warning.SYMBOL section to be unallocated. */
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#define __make_section_unallocated(section_string) \
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asm (".section " section_string "\n\t.previous");
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/* Tacking on "\n\t#" to the section name makes gcc put it's bogus
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section attributes on what looks like a comment to the assembler. */
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#ifdef HAVE_SECTION_QUOTES
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# define __sec_comment "\"\n\t#\""
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#else
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# define __sec_comment "\n\t#"
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#endif
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#define link_warning(symbol, msg) \
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__make_section_unallocated (".gnu.warning." #symbol) \
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static const char __evoke_link_warning_##symbol[] \
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__attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
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= msg;
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#define libc_freeres_ptr(decl) \
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__make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
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decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
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#define __libc_freeres_fn_section \
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__attribute__ ((section ("__libc_freeres_fn")))
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#define libc_freeres_fn(name) \
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static void name (void) __attribute_used__ __libc_freeres_fn_section; \
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text_set_element (__libc_subfreeres, name); \
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static void name (void)
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/* A canned warning for sysdeps/stub functions. */
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#define stub_warning(name) \
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__make_section_unallocated (".gnu.glibc-stub." #name) \
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link_warning (name, #name " is not implemented and will always fail")
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/* Warning for linking functions calling dlopen into static binaries. */
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#ifdef SHARED
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#define static_link_warning(name)
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#else
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#define static_link_warning(name) static_link_warning1(name)
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#define static_link_warning1(name) \
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link_warning(name, "Using '" #name "' in statically linked applications \
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requires at runtime the shared libraries from the glibc version used \
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for linking")
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#endif
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/* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
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alias to ORIGINAL, when the assembler supports such declarations
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(such as in ELF).
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This is only necessary when defining something in assembly, or playing
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funny alias games where the size should be other than what the compiler
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thinks it is. */
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#define declare_symbol_alias(symbol, original, type, size) \
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declare_symbol_alias_1 (symbol, original, type, size)
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#ifdef __ASSEMBLER__
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# define declare_symbol_alias_1(symbol, original, type, size) \
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strong_alias (original, symbol); \
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.type C_SYMBOL_NAME (symbol), %##type; \
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.size C_SYMBOL_NAME (symbol), size
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#else /* Not __ASSEMBLER__. */
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# define declare_symbol_alias_1(symbol, original, type, size) \
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asm (".globl " __SYMBOL_PREFIX #symbol \
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"\n\t" declare_symbol_alias_1_alias (symbol, original) \
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"\n\t.type " __SYMBOL_PREFIX #symbol ", " \
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"%" #type \
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"\n\t.size " __SYMBOL_PREFIX #symbol ", " #size);
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# ifdef HAVE_ASM_SET_DIRECTIVE
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# define declare_symbol_alias_1_alias(symbol, original) \
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".set " __SYMBOL_PREFIX #symbol ", " __SYMBOL_PREFIX #original
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# else
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# define declare_symbol_alias_1_alias(symbol, original) \
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__SYMBOL_PREFIX #symbol " = " __SYMBOL_PREFIX #original
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# endif /* HAVE_ASM_SET_DIRECTIVE */
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#endif /* __ASSEMBLER__ */
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/*
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*/
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/* Symbol set support macros. */
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/* Make SYMBOL, which is in the text segment, an element of SET. */
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#define text_set_element(set, symbol) _elf_set_element(set, symbol)
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/* Make SYMBOL, which is in the data segment, an element of SET. */
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#define data_set_element(set, symbol) _elf_set_element(set, symbol)
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/* Make SYMBOL, which is in the bss segment, an element of SET. */
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#define bss_set_element(set, symbol) _elf_set_element(set, symbol)
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/* These are all done the same way in ELF.
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There is a new section created for each set. */
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#ifdef SHARED
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/* When building a shared library, make the set section writable,
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because it will need to be relocated at run time anyway. */
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# define _elf_set_element(set, symbol) \
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static const void *__elf_set_##set##_element_##symbol##__ \
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__attribute__ ((used, section (#set))) = &(symbol)
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#else
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# define _elf_set_element(set, symbol) \
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static const void *const __elf_set_##set##_element_##symbol##__ \
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__attribute__ ((used, section (#set))) = &(symbol)
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#endif
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/* Define SET as a symbol set. This may be required (it is in a.out) to
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be able to use the set's contents. */
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#define symbol_set_define(set) symbol_set_declare(set)
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/* Declare SET for use in this module, if defined in another module.
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In a shared library, this is always local to that shared object.
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For static linking, the set might be wholly absent and so we use
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weak references. */
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#define symbol_set_declare(set) \
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extern char const __start_##set[] __symbol_set_attribute; \
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extern char const __stop_##set[] __symbol_set_attribute;
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#ifdef SHARED
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# define __symbol_set_attribute attribute_hidden
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#else
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# define __symbol_set_attribute __attribute__ ((weak))
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#endif
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/* Return a pointer (void *const *) to the first element of SET. */
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#define symbol_set_first_element(set) ((void *const *) (&__start_##set))
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/* Return true iff PTR (a void *const *) has been incremented
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past the last element in SET. */
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#define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
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/* Use symbol_version_reference to specify the version a symbol
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reference should link to. Use symbol_version or
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default_symbol_version for the definition of a versioned symbol.
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The difference is that the latter is a no-op in non-shared
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builds. */
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#ifdef __ASSEMBLER__
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# define symbol_version_reference(real, name, version) \
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.symver real, name##@##version
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#else /* !__ASSEMBLER__ */
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# define symbol_version_reference(real, name, version) \
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__asm__ (".symver " #real "," #name "@" #version)
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#endif
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#ifdef SHARED
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# define symbol_version(real, name, version) \
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symbol_version_reference(real, name, version)
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# define default_symbol_version(real, name, version) \
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_default_symbol_version(real, name, version)
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# ifdef __ASSEMBLER__
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# define _default_symbol_version(real, name, version) \
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.symver real, name##@##@##version
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# else
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# define _default_symbol_version(real, name, version) \
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__asm__ (".symver " #real "," #name "@@" #version)
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# endif
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#else
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# define symbol_version(real, name, version)
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# define default_symbol_version(real, name, version) \
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strong_alias(real, name)
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#endif
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#if defined SHARED || defined LIBC_NONSHARED
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# define attribute_hidden __attribute__ ((visibility ("hidden")))
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#else
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# define attribute_hidden
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#endif
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#define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
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#define attribute_relro __attribute__ ((section (".data.rel.ro")))
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/* Used to disable stack protection in sensitive places, like ifunc
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resolvers and early static TLS init. */
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#ifdef HAVE_CC_NO_STACK_PROTECTOR
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# define inhibit_stack_protector \
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__attribute__ ((__optimize__ ("-fno-stack-protector")))
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#else
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# define inhibit_stack_protector
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#endif
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/* The following macros are used for PLT bypassing within libc.so
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(and if needed other libraries similarly).
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First of all, you need to have the function prototyped somewhere,
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say in foo/foo.h:
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int foo (int __bar);
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If calls to foo within libc.so should always go to foo defined in libc.so,
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then in include/foo.h you add:
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libc_hidden_proto (foo)
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line and after the foo function definition:
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int foo (int __bar)
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{
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return __bar;
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}
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libc_hidden_def (foo)
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or
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int foo (int __bar)
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{
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return __bar;
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}
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libc_hidden_weak (foo)
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Similarly for global data. If references to foo within libc.so should
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always go to foo defined in libc.so, then in include/foo.h you add:
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libc_hidden_proto (foo)
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line and after foo's definition:
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int foo = INITIAL_FOO_VALUE;
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libc_hidden_data_def (foo)
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or
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int foo = INITIAL_FOO_VALUE;
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libc_hidden_data_weak (foo)
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If foo is normally just an alias (strong or weak) to some other function,
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you should use the normal strong_alias first, then add libc_hidden_def
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or libc_hidden_weak:
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int baz (int __bar)
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{
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return __bar;
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}
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strong_alias (baz, foo)
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libc_hidden_weak (foo)
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If the function should be internal to multiple objects, say ld.so and
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libc.so, the best way is to use:
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#if IS_IN (libc) || IS_IN (rtld)
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hidden_proto (foo)
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#endif
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in include/foo.h and the normal macros at all function definitions
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depending on what DSO they belong to.
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If versioned_symbol macro is used to define foo,
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libc_hidden_ver macro should be used, as in:
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int __real_foo (int __bar)
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{
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return __bar;
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}
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versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
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libc_hidden_ver (__real_foo, foo) */
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#if defined SHARED && !defined NO_HIDDEN
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# ifndef __ASSEMBLER__
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# define __hidden_proto_hiddenattr(attrs...) \
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__attribute__ ((visibility ("hidden"), ##attrs))
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# define hidden_proto(name, attrs...) \
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__hidden_proto (name, , __GI_##name, ##attrs)
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# define hidden_tls_proto(name, attrs...) \
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__hidden_proto (name, __thread, __GI_##name, ##attrs)
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# define __hidden_proto(name, thread, internal, attrs...) \
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extern thread __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
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__hidden_proto_hiddenattr (attrs);
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# define __hidden_asmname(name) \
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__hidden_asmname1 (__USER_LABEL_PREFIX__, name)
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# define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
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# define __hidden_asmname2(prefix, name) #prefix name
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# define __hidden_ver1(local, internal, name) \
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extern __typeof (name) __EI_##name __asm__(__hidden_asmname (#internal)); \
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extern __typeof (name) __EI_##name \
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__attribute__((alias (__hidden_asmname (#local))))
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# define hidden_ver(local, name) __hidden_ver1(local, __GI_##name, name);
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# define hidden_data_ver(local, name) hidden_ver(local, name)
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# define hidden_def(name) __hidden_ver1(__GI_##name, name, name);
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# define hidden_data_def(name) hidden_def(name)
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# define hidden_weak(name) \
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__hidden_ver1(__GI_##name, name, name) __attribute__((weak));
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# define hidden_data_weak(name) hidden_weak(name)
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# define hidden_nolink(name, lib, version) \
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__hidden_nolink1 (__GI_##name, __EI_##name, name, VERSION_##lib##_##version)
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# define __hidden_nolink1(local, internal, name, version) \
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__hidden_nolink2 (local, internal, name, version)
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||
# define __hidden_nolink2(local, internal, name, version) \
|
||
extern __typeof (name) internal __attribute__ ((alias (#local))); \
|
||
__hidden_nolink3 (local, internal, #name "@" #version)
|
||
# define __hidden_nolink3(local, internal, vername) \
|
||
__asm__ (".symver " #internal ", " vername);
|
||
# else
|
||
/* For assembly, we need to do the opposite of what we do in C:
|
||
in assembly gcc __REDIRECT stuff is not in place, so functions
|
||
are defined by its normal name and we need to create the
|
||
__GI_* alias to it, in C __REDIRECT causes the function definition
|
||
to use __GI_* name and we need to add alias to the real name.
|
||
There is no reason to use hidden_weak over hidden_def in assembly,
|
||
but we provide it for consistency with the C usage.
|
||
hidden_proto doesn't make sense for assembly but the equivalent
|
||
is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET. */
|
||
# define hidden_def(name) strong_alias (name, __GI_##name)
|
||
# define hidden_weak(name) hidden_def (name)
|
||
# define hidden_ver(local, name) strong_alias (local, __GI_##name)
|
||
# define hidden_data_def(name) strong_data_alias (name, __GI_##name)
|
||
# define hidden_data_weak(name) hidden_data_def (name)
|
||
# define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
|
||
# define HIDDEN_JUMPTARGET(name) __GI_##name
|
||
# endif
|
||
#else
|
||
# ifndef __ASSEMBLER__
|
||
# define hidden_proto(name, attrs...)
|
||
# define hidden_tls_proto(name, attrs...)
|
||
# else
|
||
# define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
|
||
# endif /* Not __ASSEMBLER__ */
|
||
# define hidden_weak(name)
|
||
# define hidden_def(name)
|
||
# define hidden_ver(local, name)
|
||
# define hidden_data_weak(name)
|
||
# define hidden_data_def(name)
|
||
# define hidden_data_ver(local, name)
|
||
# define hidden_nolink(name, lib, version)
|
||
#endif
|
||
|
||
#if IS_IN (libc)
|
||
# define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
|
||
# define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
|
||
# define libc_hidden_def(name) hidden_def (name)
|
||
# define libc_hidden_weak(name) hidden_weak (name)
|
||
# ifdef LINK_OBSOLETE_RPC
|
||
/* libc_hidden_nolink_sunrpc should only get used in sunrpc code. */
|
||
# define libc_hidden_nolink_sunrpc(name, version) hidden_def (name)
|
||
# else
|
||
# define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version)
|
||
# endif
|
||
# define libc_hidden_ver(local, name) hidden_ver (local, name)
|
||
# define libc_hidden_data_def(name) hidden_data_def (name)
|
||
# define libc_hidden_data_weak(name) hidden_data_weak (name)
|
||
# define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
|
||
#else
|
||
# define libc_hidden_proto(name, attrs...)
|
||
# define libc_hidden_tls_proto(name, attrs...)
|
||
# define libc_hidden_def(name)
|
||
# define libc_hidden_weak(name)
|
||
# define libc_hidden_ver(local, name)
|
||
# define libc_hidden_data_def(name)
|
||
# define libc_hidden_data_weak(name)
|
||
# define libc_hidden_data_ver(local, name)
|
||
#endif
|
||
|
||
#if IS_IN (rtld)
|
||
# define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
|
||
# define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
|
||
# define rtld_hidden_def(name) hidden_def (name)
|
||
# define rtld_hidden_weak(name) hidden_weak (name)
|
||
# define rtld_hidden_ver(local, name) hidden_ver (local, name)
|
||
# define rtld_hidden_data_def(name) hidden_data_def (name)
|
||
# define rtld_hidden_data_weak(name) hidden_data_weak (name)
|
||
# define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
|
||
#else
|
||
# define rtld_hidden_proto(name, attrs...)
|
||
# define rtld_hidden_tls_proto(name, attrs...)
|
||
# define rtld_hidden_def(name)
|
||
# define rtld_hidden_weak(name)
|
||
# define rtld_hidden_ver(local, name)
|
||
# define rtld_hidden_data_def(name)
|
||
# define rtld_hidden_data_weak(name)
|
||
# define rtld_hidden_data_ver(local, name)
|
||
#endif
|
||
|
||
#if IS_IN (libm)
|
||
# define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
|
||
# define libm_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
|
||
# define libm_hidden_def(name) hidden_def (name)
|
||
# define libm_hidden_weak(name) hidden_weak (name)
|
||
# define libm_hidden_ver(local, name) hidden_ver (local, name)
|
||
# define libm_hidden_data_def(name) hidden_data_def (name)
|
||
# define libm_hidden_data_weak(name) hidden_data_weak (name)
|
||
# define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
|
||
#else
|
||
# define libm_hidden_proto(name, attrs...)
|
||
# define libm_hidden_tls_proto(name, attrs...)
|
||
# define libm_hidden_def(name)
|
||
# define libm_hidden_weak(name)
|
||
# define libm_hidden_ver(local, name)
|
||
# define libm_hidden_data_def(name)
|
||
# define libm_hidden_data_weak(name)
|
||
# define libm_hidden_data_ver(local, name)
|
||
#endif
|
||
|
||
#if IS_IN (libmvec)
|
||
# define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
|
||
# define libmvec_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
|
||
# define libmvec_hidden_def(name) hidden_def (name)
|
||
# define libmvec_hidden_weak(name) hidden_weak (name)
|
||
# define libmvec_hidden_ver(local, name) hidden_ver (local, name)
|
||
# define libmvec_hidden_data_def(name) hidden_data_def (name)
|
||
# define libmvec_hidden_data_weak(name) hidden_data_weak (name)
|
||
# define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
|
||
#else
|
||
# define libmvec_hidden_proto(name, attrs...)
|
||
# define libmvec_hidden_tls_proto(name, attrs...)
|
||
# define libmvec_hidden_def(name)
|
||
# define libmvec_hidden_weak(name)
|
||
# define libmvec_hidden_ver(local, name)
|
||
# define libmvec_hidden_data_def(name)
|
||
# define libmvec_hidden_data_weak(name)
|
||
# define libmvec_hidden_data_ver(local, name)
|
||
#endif
|
||
|
||
#if IS_IN (libresolv)
|
||
# define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
|
||
# define libresolv_hidden_tls_proto(name, attrs...) \
|
||
hidden_tls_proto (name, ##attrs)
|
||
# define libresolv_hidden_def(name) hidden_def (name)
|
||
# define libresolv_hidden_weak(name) hidden_weak (name)
|
||
# define libresolv_hidden_ver(local, name) hidden_ver (local, name)
|
||
# define libresolv_hidden_data_def(name) hidden_data_def (name)
|
||
# define libresolv_hidden_data_weak(name) hidden_data_weak (name)
|
||
# define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
|
||
#else
|
||
# define libresolv_hidden_proto(name, attrs...)
|
||
# define libresolv_hidden_tls_proto(name, attrs...)
|
||
# define libresolv_hidden_def(name)
|
||
# define libresolv_hidden_weak(name)
|
||
# define libresolv_hidden_ver(local, name)
|
||
# define libresolv_hidden_data_def(name)
|
||
# define libresolv_hidden_data_weak(name)
|
||
# define libresolv_hidden_data_ver(local, name)
|
||
#endif
|
||
|
||
#if IS_IN (librt)
|
||
# define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
|
||
# define librt_hidden_tls_proto(name, attrs...) \
|
||
hidden_tls_proto (name, ##attrs)
|
||
# define librt_hidden_def(name) hidden_def (name)
|
||
# define librt_hidden_weak(name) hidden_weak (name)
|
||
# define librt_hidden_ver(local, name) hidden_ver (local, name)
|
||
# define librt_hidden_data_def(name) hidden_data_def (name)
|
||
# define librt_hidden_data_weak(name) hidden_data_weak (name)
|
||
# define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
|
||
#else
|
||
# define librt_hidden_proto(name, attrs...)
|
||
# define librt_hidden_tls_proto(name, attrs...)
|
||
# define librt_hidden_def(name)
|
||
# define librt_hidden_weak(name)
|
||
# define librt_hidden_ver(local, name)
|
||
# define librt_hidden_data_def(name)
|
||
# define librt_hidden_data_weak(name)
|
||
# define librt_hidden_data_ver(local, name)
|
||
#endif
|
||
|
||
#if IS_IN (libdl)
|
||
# define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
|
||
# define libdl_hidden_tls_proto(name, attrs...) \
|
||
hidden_tls_proto (name, ##attrs)
|
||
# define libdl_hidden_def(name) hidden_def (name)
|
||
# define libdl_hidden_weak(name) hidden_weak (name)
|
||
# define libdl_hidden_ver(local, name) hidden_ver (local, name)
|
||
# define libdl_hidden_data_def(name) hidden_data_def (name)
|
||
# define libdl_hidden_data_weak(name) hidden_data_weak (name)
|
||
# define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
|
||
#else
|
||
# define libdl_hidden_proto(name, attrs...)
|
||
# define libdl_hidden_tls_proto(name, attrs...)
|
||
# define libdl_hidden_def(name)
|
||
# define libdl_hidden_weak(name)
|
||
# define libdl_hidden_ver(local, name)
|
||
# define libdl_hidden_data_def(name)
|
||
# define libdl_hidden_data_weak(name)
|
||
# define libdl_hidden_data_ver(local, name)
|
||
#endif
|
||
|
||
#if IS_IN (libnss_files)
|
||
# define libnss_files_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
|
||
# define libnss_files_hidden_tls_proto(name, attrs...) \
|
||
hidden_tls_proto (name, ##attrs)
|
||
# define libnss_files_hidden_def(name) hidden_def (name)
|
||
# define libnss_files_hidden_weak(name) hidden_weak (name)
|
||
# define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
|
||
# define libnss_files_hidden_data_def(name) hidden_data_def (name)
|
||
# define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
|
||
# define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
|
||
#else
|
||
# define libnss_files_hidden_proto(name, attrs...)
|
||
# define libnss_files_hidden_tls_proto(name, attrs...)
|
||
# define libnss_files_hidden_def(name)
|
||
# define libnss_files_hidden_weak(name)
|
||
# define libnss_files_hidden_ver(local, name)
|
||
# define libnss_files_hidden_data_def(name)
|
||
# define libnss_files_hidden_data_weak(name)
|
||
# define libnss_files_hidden_data_ver(local, name)
|
||
#endif
|
||
|
||
#if IS_IN (libnsl)
|
||
# define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
|
||
# define libnsl_hidden_tls_proto(name, attrs...) \
|
||
hidden_tls_proto (name, ##attrs)
|
||
# define libnsl_hidden_def(name) hidden_def (name)
|
||
# define libnsl_hidden_weak(name) hidden_weak (name)
|
||
# define libnsl_hidden_ver(local, name) hidden_ver (local, name)
|
||
# define libnsl_hidden_data_def(name) hidden_data_def (name)
|
||
# define libnsl_hidden_data_weak(name) hidden_data_weak (name)
|
||
# define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
|
||
#else
|
||
# define libnsl_hidden_proto(name, attrs...)
|
||
# define libnsl_hidden_tls_proto(name, attrs...)
|
||
# define libnsl_hidden_def(name)
|
||
# define libnsl_hidden_weak(name)
|
||
# define libnsl_hidden_ver(local, name)
|
||
# define libnsl_hidden_data_def(name)
|
||
# define libnsl_hidden_data_weak(name)
|
||
# define libnsl_hidden_data_ver(local, name)
|
||
#endif
|
||
|
||
#if IS_IN (libnss_nisplus)
|
||
# define libnss_nisplus_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
|
||
# define libnss_nisplus_hidden_tls_proto(name, attrs...) \
|
||
hidden_tls_proto (name, ##attrs)
|
||
# define libnss_nisplus_hidden_def(name) hidden_def (name)
|
||
# define libnss_nisplus_hidden_weak(name) hidden_weak (name)
|
||
# define libnss_nisplus_hidden_ver(local, name) hidden_ver (local, name)
|
||
# define libnss_nisplus_hidden_data_def(name) hidden_data_def (name)
|
||
# define libnss_nisplus_hidden_data_weak(name) hidden_data_weak (name)
|
||
# define libnss_nisplus_hidden_data_ver(local, name) hidden_data_ver (local, name)
|
||
#else
|
||
# define libnss_nisplus_hidden_proto(name, attrs...)
|
||
# define libnss_nisplus_hidden_tls_proto(name, attrs...)
|
||
# define libnss_nisplus_hidden_def(name)
|
||
# define libnss_nisplus_hidden_weak(name)
|
||
# define libnss_nisplus_hidden_ver(local, name)
|
||
# define libnss_nisplus_hidden_data_def(name)
|
||
# define libnss_nisplus_hidden_data_weak(name)
|
||
# define libnss_nisplus_hidden_data_ver(local, name)
|
||
#endif
|
||
|
||
#define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
|
||
#define libc_hidden_builtin_def(name) libc_hidden_def (name)
|
||
#define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
|
||
#define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
|
||
#ifdef __ASSEMBLER__
|
||
# define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
|
||
#endif
|
||
|
||
#if IS_IN (libutil)
|
||
# define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
|
||
# define libutil_hidden_tls_proto(name, attrs...) \
|
||
hidden_tls_proto (name, ##attrs)
|
||
# define libutil_hidden_def(name) hidden_def (name)
|
||
# define libutil_hidden_weak(name) hidden_weak (name)
|
||
# define libutil_hidden_ver(local, name) hidden_ver (local, name)
|
||
# define libutil_hidden_data_def(name) hidden_data_def (name)
|
||
# define libutil_hidden_data_weak(name) hidden_data_weak (name)
|
||
# define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
|
||
#else
|
||
# define libutil_hidden_proto(name, attrs...)
|
||
# define libutil_hidden_tls_proto(name, attrs...)
|
||
# define libutil_hidden_def(name)
|
||
# define libutil_hidden_weak(name)
|
||
# define libutil_hidden_ver(local, name)
|
||
# define libutil_hidden_data_def(name)
|
||
# define libutil_hidden_data_weak(name)
|
||
# define libutil_hidden_data_ver(local, name)
|
||
#endif
|
||
|
||
/* Get some dirty hacks. */
|
||
#include <symbol-hacks.h>
|
||
|
||
/* Move compatibility symbols out of the way by placing them all in a
|
||
special section. */
|
||
#ifndef __ASSEMBLER__
|
||
# define attribute_compat_text_section \
|
||
__attribute__ ((section (".text.compat")))
|
||
# define attribute_compat_data_section \
|
||
__attribute__ ((section (".data.compat")))
|
||
#else
|
||
# define compat_text_section .section ".text.compat", "ax";
|
||
# define compat_data_section .section ".data.compat", "aw";
|
||
#endif
|
||
|
||
/* Helper / base macros for indirect function symbols. */
|
||
#define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \
|
||
classifier inhibit_stack_protector void *name##_ifunc (arg) \
|
||
{ \
|
||
init (); \
|
||
__typeof (type_name) *res = expr; \
|
||
return res; \
|
||
}
|
||
|
||
#ifdef HAVE_GCC_IFUNC
|
||
# define __ifunc(type_name, name, expr, arg, init) \
|
||
extern __typeof (type_name) name __attribute__ \
|
||
((ifunc (#name "_ifunc"))); \
|
||
__ifunc_resolver (type_name, name, expr, arg, init, static)
|
||
|
||
# define __ifunc_hidden(type_name, name, expr, arg, init) \
|
||
__ifunc (type_name, name, expr, arg, init)
|
||
#else
|
||
/* Gcc does not support __attribute__ ((ifunc (...))). Use the old behaviour
|
||
as fallback. But keep in mind that the debug information for the ifunc
|
||
resolver functions is not correct. It contains the ifunc'ed function as
|
||
DW_AT_linkage_name. E.g. lldb uses this field and an inferior function
|
||
call of the ifunc'ed function will fail due to "no matching function for
|
||
call to ..." because the ifunc'ed function and the resolver function have
|
||
different signatures. (Gcc support is disabled at least on a ppc64le
|
||
Ubuntu 14.04 system.) */
|
||
|
||
# define __ifunc(type_name, name, expr, arg, init) \
|
||
extern __typeof (type_name) name; \
|
||
void *name##_ifunc (arg) __asm__ (#name); \
|
||
__ifunc_resolver (type_name, name, expr, arg, init,) \
|
||
__asm__ (".type " #name ", %gnu_indirect_function");
|
||
|
||
# define __ifunc_hidden(type_name, name, expr, arg, init) \
|
||
extern __typeof (type_name) __libc_##name; \
|
||
__ifunc (type_name, __libc_##name, expr, arg, init) \
|
||
strong_alias (__libc_##name, name);
|
||
#endif /* !HAVE_GCC_IFUNC */
|
||
|
||
/* The following macros are used for indirect function symbols in libc.so.
|
||
First of all, you need to have the function prototyped somewhere,
|
||
say in foo.h:
|
||
|
||
int foo (int __bar);
|
||
|
||
If you have an implementation for foo which e.g. uses a special hardware
|
||
feature which isn't available on all machines where this libc.so will be
|
||
used but decideable if available at runtime e.g. via hwcaps, you can provide
|
||
two or multiple implementations of foo:
|
||
|
||
int __foo_default (int __bar)
|
||
{
|
||
return __bar;
|
||
}
|
||
|
||
int __foo_special (int __bar)
|
||
{
|
||
return __bar;
|
||
}
|
||
|
||
If your function foo has no libc_hidden_proto (foo) defined for PLT
|
||
bypassing, you can use:
|
||
|
||
#define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
|
||
|
||
libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
|
||
|
||
This will define a resolver function for foo which returns __foo_special or
|
||
__foo_default depending on your specified expression. Please note that you
|
||
have to define a macro function INIT_ARCH before using libc_ifunc macro as
|
||
it is called by the resolver function before evaluating the specified
|
||
expression. In this example it is used to prepare the hwcap variable.
|
||
The resolver function is assigned to an ifunc'ed symbol foo. Calls to foo
|
||
from inside or outside of libc.so will be indirected by a PLT call.
|
||
|
||
If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
|
||
and calls to foo within libc.so should always go to one specific
|
||
implementation of foo e.g. __foo_default then you have to add:
|
||
|
||
__hidden_ver1 (__foo_default, __GI_foo, __foo_default);
|
||
|
||
or a tweaked definition of libc_hidden_def macro after the __foo_default
|
||
function definition. Calls to foo within libc.so will always go directly to
|
||
__foo_default. Calls to foo from outside libc.so will be indirected by a
|
||
PLT call to ifunc'ed symbol foo which you have to define in a separate
|
||
compile unit:
|
||
|
||
#define foo __redirect_foo
|
||
#include <foo.h>
|
||
#undef foo
|
||
|
||
extern __typeof (__redirect_foo) __foo_default attribute_hidden;
|
||
extern __typeof (__redirect_foo) __foo_special attribute_hidden;
|
||
|
||
libc_ifunc_redirected (__redirect_foo, foo,
|
||
(hwcap & HWCAP_SPECIAL)
|
||
? __foo_special
|
||
: __foo_default);
|
||
|
||
This will define the ifunc'ed symbol foo like above. The redirection of foo
|
||
in header file is needed to omit an additional defintion of __GI_foo which
|
||
would end in a linker error while linking libc.so. You have to specify
|
||
__redirect_foo as first parameter which is used within libc_ifunc_redirected
|
||
macro in conjunction with typeof to define the ifunc'ed symbol foo.
|
||
|
||
If your function foo has a libc_hidden_proto (foo) defined and calls to foo
|
||
within or from outside libc.so should go via ifunc'ed symbol, then you have
|
||
to use:
|
||
|
||
libc_ifunc_hidden (foo, foo,
|
||
(hwcap & HWCAP_SPECIAL)
|
||
? __foo_special
|
||
: __foo_default);
|
||
libc_hidden_def (foo)
|
||
|
||
The first parameter foo of libc_ifunc_hidden macro is used in the same way
|
||
as for libc_ifunc_redirected macro. */
|
||
|
||
#define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
|
||
|
||
#define libc_ifunc_redirected(redirected_name, name, expr) \
|
||
__ifunc (redirected_name, name, expr, void, INIT_ARCH)
|
||
|
||
#define libc_ifunc_hidden(redirected_name, name, expr) \
|
||
__ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
|
||
|
||
/* The body of the function is supposed to use __get_cpu_features
|
||
which will, if necessary, initialize the data first. */
|
||
#define libm_ifunc_init()
|
||
#define libm_ifunc(name, expr) \
|
||
__ifunc (name, name, expr, void, libm_ifunc_init)
|
||
|
||
/* Add the compiler optimization to inhibit loop transformation to library
|
||
calls. This is used to avoid recursive calls in memset and memmove
|
||
default implementations. */
|
||
#ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
|
||
# define inhibit_loop_to_libcall \
|
||
__attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
|
||
#else
|
||
# define inhibit_loop_to_libcall
|
||
#endif
|
||
|
||
#endif /* libc-symbols.h */
|