lkml.org 
[lkml]   [2018]   [Feb]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 2/6] s390: add optimized array_index_mask_nospec
    Date
    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>
    ---
    arch/s390/include/asm/barrier.h | 24 ++++++++++++++++++++++++
    1 file changed, 24 insertions(+)

    diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
    index 1043260..f9eddbc 100644
    --- 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 */
    --
    2.7.4
    \
     
     \ /
      Last update: 2018-02-07 08:02    [W:2.960 / U:0.304 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site