Commit ee19370c authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

s390/atomic_ops: Improve __atomic_set() for small values 



Use mvhi/mvghi for small constant values within the __atomic_set()
inline assemblies. This avoids loading the specified value into a
register.

The size of the kernel image is reduced by ~1.2kb.

Reviewed-by: default avatarJuergen Christ <jchrist@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent f2ed8367

arch/s390/include/asm/atomic_ops.h

+20 −6
Original line number Diff line number Diff line
@@ -8,6 +8,8 @@ 
#ifndef __ARCH_S390_ATOMIC_OPS__

#define __ARCH_S390_ATOMIC_OPS__



#include <linux/limits.h>



static __always_inline int __atomic_read(const atomic_t *v)

{

	int c;
@@ -20,10 +22,16 @@ static __always_inline int __atomic_read(const atomic_t *v) 


static __always_inline void __atomic_set(atomic_t *v, int i)

{

	if (__builtin_constant_p(i) && i >= S16_MIN && i <= S16_MAX) {

		asm volatile(

			"	mvhi	%[counter], %[i]\n"

			: [counter] "=Q" (v->counter) : [i] "K" (i));

	} else {

		asm volatile(

			"	st	%[i],%[counter]\n"

			: [counter] "=R" (v->counter) : [i] "d" (i));

	}

}



static __always_inline s64 __atomic64_read(const atomic64_t *v)

{
@@ -37,10 +45,16 @@ static __always_inline s64 __atomic64_read(const atomic64_t *v) 


static __always_inline void __atomic64_set(atomic64_t *v, s64 i)

{

	if (__builtin_constant_p(i) && i >= S16_MIN && i <= S16_MAX) {

		asm volatile(

			"	mvghi	%[counter], %[i]\n"

			: [counter] "=Q" (v->counter) : [i] "K" (i));

	} else {

		asm volatile(

			"	stg	%[i],%[counter]\n"

			: [counter] "=RT" (v->counter) : [i] "d" (i));

	}

}



#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES