4.14-stable review patch. If anyone has any objections, please let me know.
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From: Martin Schwidefsky schwidefsky@de.ibm.com
[ Upstream commit e2dd833389cc4069a96b57bdd24227b5f52288f5 ]
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: Martin Schwidefsky schwidefsky@de.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/s390/include/asm/barrier.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
--- a/arch/s390/include/asm/barrier.h +++ b/arch/s390/include/asm/barrier.h @@ -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 */