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Introduce symbol_visibility.h with macros to define hidden functions

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These were used in function_remapper.cpp but can be used elsewhere too,
so move them to a private header. Also use them for the stack protector
hidden function definition (probably not so useful since gcc2 doesn't
support using the stack protector anyway?).

The gcc2 way to make a symbol hidden is to manually generate the .hidden
directive in the assembler output. This is not perfect: it is hard to
use for C++ functions and methods (manual mangling of the name is
needed), and inline assembler can only be inserted inside functions. But
the alternative is patching gcc2 to add support for the function
attribute, and I don't want to dig into that today.
This commit is contained in:
Adrien Destugues 2021-10-09 15:03:36 +02:00
parent cfa6534031
commit 857c79a6b8
5 changed files with 27 additions and 13 deletions
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1
headers/os/BeBuild.h
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@ -82,6 +82,7 @@
#define _PACKED __attribute__((packed))
#define _PRINTFLIKE(_format_, _args_) \
__attribute__((format(__printf__, _format_, _args_)))
#if __GNUC__ >= 4
# define _EXPORT __attribute__((visibility("default")))
# define B_ALWAYS_INLINE __attribute__((always_inline)) inline

19
headers/private/system/symbol_visibility.h Normal file
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@ -0,0 +1,19 @@
/*
* Copyright 2011, Ingo Weinhold, ingo_weinhold@gmx.de.
* Distributed under the terms of the MIT License.
*/
#ifndef SYMBOL_VISIBILITY_H
#define SYMBOL_VISIBILITY_H
#if __GNUC__ >= 4
# define HIDDEN_FUNCTION(function) do {} while (0)
# define HIDDEN_FUNCTION_ATTRIBUTE __attribute__((visibility("hidden")))
#else
# define HIDDEN_FUNCTION(function) asm volatile(".hidden " #function)
# define HIDDEN_FUNCTION_ATTRIBUTE
#endif
#endif /* !SYMBOL_VISIBILITY_H */

1
src/build/libroot/Jamfile
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@ -10,6 +10,7 @@ UseHeaders [ FDirName $(HAIKU_TOP) headers build os storage ] : true ;
UseHeaders [ FDirName $(HAIKU_TOP) headers build os support ] : true ;
UsePrivateBuildHeaders kernel libroot system ;
UsePrivateHeaders system ;
{
local defines = [ FDefines

11
src/build/libroot/function_remapper.cpp
View File

@ -7,18 +7,11 @@
#include <stdarg.h>
#include <fcntl.h>
#include "symbol_visibility.h"
#include "remapped_functions.h"
#if __GNUC__ >= 4
# define HIDDEN_FUNCTION(function) do {} while (0)
# define HIDDEN_FUNCTION_ATTRIBUTE __attribute__((visibility("hidden")))
#else
# define HIDDEN_FUNCTION(function) asm volatile(".hidden " #function)
# define HIDDEN_FUNCTION_ATTRIBUTE
#endif
extern "C" int HIDDEN_FUNCTION_ATTRIBUTE
fchmod(int fd, mode_t mode)
{

8
src/system/libroot/os/stack_protector.cpp
View File

@ -9,6 +9,8 @@
#include <stdlib.h>
#include <sys/cdefs.h>
#include "private/system/symbol_visibility.h"
extern "C" {
@ -41,6 +43,7 @@ __init_stack_protector()
void
__stack_chk_fail()
{
HIDDEN_FUNCTION(__stack_chk_fail_local);
sigset_t mask;
sigfillset(&mask);
sigdelset(&mask, SIGABRT);
@ -51,8 +54,5 @@ __stack_chk_fail()
}
#if __GNUC__ >= 4
extern "C" void __stack_chk_fail_local() __attribute__((visibility("hidden")));
extern "C" void __stack_chk_fail_local() HIDDEN_FUNCTION_ATTRIBUTE;
__weak_reference(__stack_chk_fail, __stack_chk_fail_local);
#endif