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Commit ed79e946 authored by Heiko Carstens's avatar Heiko Carstens Committed by Ingo Molnar
Browse files

s390/uaccess, locking/static_keys: employ static_branch_likely() 



Use the new static_branch_likely() primitive to make sure that the
most likely case is executed without taking an unconditional branch.
This wasn't possible with the old jump label primitives.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20150729064600.GB3953@osiris


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 3bbfafb7

arch/s390/lib/uaccess.c

+6 −6
Original line number Diff line number Diff line
@@ -15,7 +15,7 @@ 
#include <asm/mmu_context.h>

#include <asm/facility.h>



static struct static_key have_mvcos = STATIC_KEY_INIT_FALSE;

static DEFINE_STATIC_KEY_FALSE(have_mvcos);



static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr,

						 unsigned long size)
@@ -104,7 +104,7 @@ static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr, 


unsigned long __copy_from_user(void *to, const void __user *from, unsigned long n)

{

	if (static_key_false(&have_mvcos))

	if (static_branch_likely(&have_mvcos))

		return copy_from_user_mvcos(to, from, n);

	return copy_from_user_mvcp(to, from, n);

}
@@ -177,7 +177,7 @@ static inline unsigned long copy_to_user_mvcs(void __user *ptr, const void *x, 


unsigned long __copy_to_user(void __user *to, const void *from, unsigned long n)

{

	if (static_key_false(&have_mvcos))

	if (static_branch_likely(&have_mvcos))

		return copy_to_user_mvcos(to, from, n);

	return copy_to_user_mvcs(to, from, n);

}
@@ -240,7 +240,7 @@ static inline unsigned long copy_in_user_mvc(void __user *to, const void __user 


unsigned long __copy_in_user(void __user *to, const void __user *from, unsigned long n)

{

	if (static_key_false(&have_mvcos))

	if (static_branch_likely(&have_mvcos))

		return copy_in_user_mvcos(to, from, n);

	return copy_in_user_mvc(to, from, n);

}
@@ -312,7 +312,7 @@ static inline unsigned long clear_user_xc(void __user *to, unsigned long size) 


unsigned long __clear_user(void __user *to, unsigned long size)

{

	if (static_key_false(&have_mvcos))

	if (static_branch_likely(&have_mvcos))

			return clear_user_mvcos(to, size);

	return clear_user_xc(to, size);

}
@@ -386,7 +386,7 @@ early_param("uaccess_primary", parse_uaccess_pt); 
static int __init uaccess_init(void)

{

	if (!uaccess_primary && test_facility(27))

		static_key_slow_inc(&have_mvcos);

		static_branch_enable(&have_mvcos);

	return 0;

}

early_initcall(uaccess_init);