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Commit e2dd8333 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390: add optimized array_index_mask_nospec 



Add an optimized version of the array_index_mask_nospec function for
s390 based on a compare and a subtract with borrow.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 7041d281

arch/s390/include/asm/barrier.h

+24 −0
Original line number Diff line number Diff line
@@ -49,6 +49,30 @@ do { \ 
#define __smp_mb__before_atomic()	barrier()

#define __smp_mb__after_atomic()	barrier()



/**

 * array_index_mask_nospec - generate a mask for array_idx() that is

 * ~0UL when the bounds check succeeds and 0 otherwise

 * @index: array element index

 * @size: number of elements in array

 */

#define array_index_mask_nospec array_index_mask_nospec

static inline unsigned long array_index_mask_nospec(unsigned long index,

						    unsigned long size)

{

	unsigned long mask;



	if (__builtin_constant_p(size) && size > 0) {

		asm("	clgr	%2,%1\n"

		    "	slbgr	%0,%0\n"

		    :"=d" (mask) : "d" (size-1), "d" (index) :"cc");

		return mask;

	}

	asm("	clgr	%1,%2\n"

	    "	slbgr	%0,%0\n"

	    :"=d" (mask) : "d" (size), "d" (index) :"cc");

	return ~mask;

}



#include <asm-generic/barrier.h>



#endif /* __ASM_BARRIER_H */