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Delay initialization of CPU features struct in static binaries

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Allow the CPU features structure set up to be overridden by tunables
by delaying it to until after tunables are initialized.  The
initialization is already delayed in dynamically linked glibc, it is
only in static binaries that the initialization is set early to allow
it to influence IFUNC relocations that happen in libc-start.  It is a
bit too early however and there is a good place between tunables
initialization and IFUNC relocations where this can be done.

Verified that this does not regress the testsuite.

	* csu/libc-start.c [!ARCH_INIT_CPU_FEATURES]: Define
	ARCH_INIT_CPU_FEATURES.
	(LIBC_START_MAIN): Call it.
	* sysdeps/unix/sysv/linux/aarch64/libc-start.c
	(__libc_start_main): Remove.
	(ARCH_INIT_CPU_FEATURES): New macro.
	* sysdeps/x86/libc-start.c (__libc_start_main): Remove.
	(ARCH_INIT_CPU_FEATURES): New macro.
This commit is contained in:
Siddhesh Poyarekar 2017-05-31 06:38:32 +05:30
parent 2e0bbbfbf9
commit 4158ba082c
4 changed files with 27 additions and 36 deletions
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11
ChangeLog
View File

@ -1,3 +1,14 @@
2017-05-31 Siddhesh Poyarekar <siddhesh@sourceware.org>
* csu/libc-start.c [!ARCH_INIT_CPU_FEATURES]: Define
ARCH_INIT_CPU_FEATURES.
(LIBC_START_MAIN): Call it.
* sysdeps/unix/sysv/linux/aarch64/libc-start.c
(__libc_start_main): Remove.
(ARCH_INIT_CPU_FEATURES): New macro.
* sysdeps/x86/libc-start.c (__libc_start_main): Remove.
(ARCH_INIT_CPU_FEATURES): New macro.
2017-05-30 Dennis Wölfing <denniswoelfing@gmx.de>
Rüdiger Sonderfeld <ruediger@c-plusplus.de>

6
csu/libc-start.c
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@ -104,6 +104,10 @@ apply_irel (void)
# define MAIN_AUXVEC_PARAM
#endif
#ifndef ARCH_INIT_CPU_FEATURES
# define ARCH_INIT_CPU_FEATURES()
#endif
STATIC int LIBC_START_MAIN (int (*main) (int, char **, char **
MAIN_AUXVEC_DECL),
int argc,
@ -182,6 +186,8 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
__tunables_init (__environ);
ARCH_INIT_CPU_FEATURES ();
/* Perform IREL{,A} relocations. */
apply_irel ();

23
sysdeps/unix/sysv/linux/aarch64/libc-start.c
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@ -16,26 +16,13 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifdef SHARED
# include <csu/libc-start.c>
# else
/* The main work is done in the generic function. */
# define LIBC_START_DISABLE_INLINE
# define LIBC_START_MAIN generic_start_main
# include <csu/libc-start.c>
#ifndef SHARED
# include <ldsodefs.h>
# include <cpu-features.c>
extern struct cpu_features _dl_aarch64_cpu_features;
int
__libc_start_main (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
int argc, char **argv,
__typeof (main) init,
void (*fini) (void),
void (*rtld_fini) (void), void *stack_end)
{
init_cpu_features (&_dl_aarch64_cpu_features);
return generic_start_main (main, argc, argv, init, fini, rtld_fini,
stack_end);
}
# define ARCH_INIT_CPU_FEATURES() init_cpu_features (&_dl_aarch64_cpu_features)
#endif
#include <csu/libc-start.c>

23
sysdeps/x86/libc-start.c
View File

@ -15,27 +15,14 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifdef SHARED
# include <csu/libc-start.c>
# else
/* The main work is done in the generic function. */
# define LIBC_START_DISABLE_INLINE
# define LIBC_START_MAIN generic_start_main
# include <csu/libc-start.c>
#ifndef SHARED
#include <ldsodefs.h>
# include <cpu-features.h>
# include <cpu-features.c>
extern struct cpu_features _dl_x86_cpu_features;
int
__libc_start_main (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
int argc, char **argv,
__typeof (main) init,
void (*fini) (void),
void (*rtld_fini) (void), void *stack_end)
{
init_cpu_features (&_dl_x86_cpu_features);
return generic_start_main (main, argc, argv, init, fini, rtld_fini,
stack_end);
}
#define ARCH_INIT_CPU_FEATURES() init_cpu_features (&_dl_x86_cpu_features)
#endif
# include <csu/libc-start.c>