nptl: Move elision implementations into libc

The elision interfaces are closely aligned between the targets that
implement them, so declare them in the generic <lowlevellock.h>
file.

Empty .c stubs are provided, so that fewer makefile updates
under sysdeps are needed.  Also simplify initialization via
__libc_early_init.

The symbols __lll_clocklock_elision, __lll_lock_elision,
__lll_trylock_elision, __lll_unlock_elision, __pthread_force_elision
move into libc.  For the time being, non-hidden references are used
from libpthread to access them, but once that part of libpthread
is moved into libc, hidden symbols will be used again.  (Hidden
references seem desirable to reduce the likelihood of transactions
aborts.)

1 files changed, 2 insertions, 23 deletions

diff --git a/sysdeps/unix/sysv/linux/x86/elision-conf.c b/sysdeps/unix/sysv/linux/x86/elision-conf.c
index e8ffe022f0..a5a4043d15 100644
--- a/sysdeps/unix/sysv/linux/x86/elision-conf.c
+++ b/sysdeps/unix/sysv/linux/x86/elision-conf.c
@@ -48,13 +48,6 @@ struct elision_config __elision_aconf =
     .skip_trylock_internal_abort = 3,
   };
 
-/* Force elision for all new locks.  This is used to decide whether existing
-   DEFAULT locks should be automatically upgraded to elision in
-   pthread_mutex_lock().  Disabled for suid programs.  Only used when elision
-   is available.  */
-
-int __pthread_force_elision attribute_hidden = 0;
-
 #if HAVE_TUNABLES
 static __always_inline void
 do_set_elision_enable (int32_t elision_enable)
@@ -98,10 +91,8 @@ TUNABLE_CALLBACK_FNDECL (skip_trylock_internal_abort, int32_t);
 
 /* Initialize elision.  */
 
-static void
-elision_init (int argc __attribute__ ((unused)),
-	      char **argv  __attribute__ ((unused)),
-	      char **environ)
+void
+__lll_elision_init (void)
 {
 #if HAVE_TUNABLES
   /* Elision depends on tunables and must be explicitly turned on by setting
@@ -122,15 +113,3 @@ elision_init (int argc __attribute__ ((unused)),
   if (!__pthread_force_elision)
     __elision_aconf.retry_try_xbegin = 0; /* Disable elision on rwlocks.  */
 }
-
-#ifdef SHARED
-# define INIT_SECTION ".init_array"
-#else
-# define INIT_SECTION ".preinit_array"
-#endif
-
-void (*const __pthread_init_array []) (int, char **, char **)
-  __attribute__ ((section (INIT_SECTION), aligned (sizeof (void *)))) =
-{
-  &elision_init
-};