1 files changed, 32 insertions, 25 deletions

diff --git a/arch/powerpc/include/asm/word-at-a-time.h b/arch/powerpc/include/asm/word-at-a-time.h
index 213a5f2b0717..9a5c928bb3c6 100644
--- a/arch/powerpc/include/asm/word-at-a-time.h
+++ b/arch/powerpc/include/asm/word-at-a-time.h
@@ -42,13 +42,6 @@ static inline bool has_zero(unsigned long val, unsigned long *data, const struct
 
 #else
 
-/*
- * This is largely generic for little-endian machines, but the
- * optimal byte mask counting is probably going to be something
- * that is architecture-specific. If you have a reliably fast
- * bit count instruction, that might be better than the multiply
- * and shift, for example.
- */
 struct word_at_a_time {
         const unsigned long one_bits, high_bits;
 };
@@ -57,19 +50,32 @@ struct word_at_a_time {
 
 #ifdef CONFIG_64BIT
 
-/*
- * Jan Achrenius on G+: microoptimized version of
- * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
- * that works for the bytemasks without having to
- * mask them first.
- */
-static inline long count_masked_bytes(unsigned long mask)
+/* Alan Modra's little-endian strlen tail for 64-bit */
+#define create_zero_mask(mask) (mask)
+
+static inline unsigned long find_zero(unsigned long mask)
 {
-        return mask*0x0001020304050608ul >> 56;
+        unsigned long leading_zero_bits;
+        long trailing_zero_bit_mask;
+
+        asm ("addi %1,%2,-1\n\t"
+             "andc %1,%1,%2\n\t"
+             "popcntd %0,%1"
+             : "=r" (leading_zero_bits), "=&r" (trailing_zero_bit_mask)
+             : "r" (mask));
+        return leading_zero_bits >> 3;
 }
 
 #else   /* 32-bit case */
 
+/*
+ * This is largely generic for little-endian machines, but the
+ * optimal byte mask counting is probably going to be something
+ * that is architecture-specific. If you have a reliably fast
+ * bit count instruction, that might be better than the multiply
+ * and shift, for example.
+ */
+
 /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
 static inline long count_masked_bytes(long mask)
 {
@@ -79,6 +85,17 @@ static inline long count_masked_bytes(long mask)
         return a & mask;
 }
 
+static inline unsigned long create_zero_mask(unsigned long bits)
+{
+        bits = (bits - 1) & ~bits;
+        return bits >> 7;
+}
+
+static inline unsigned long find_zero(unsigned long mask)
+{
+        return count_masked_bytes(mask);
+}
+
 #endif
 
 /* Return nonzero if it has a zero */
@@ -94,19 +111,9 @@ static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits,
         return bits;
 }
 
-static inline unsigned long create_zero_mask(unsigned long bits)
-{
-        bits = (bits - 1) & ~bits;
-        return bits >> 7;
-}
-
 /* The mask we created is directly usable as a bytemask */
 #define zero_bytemask(mask) (mask)
 
-static inline unsigned long find_zero(unsigned long mask)
-{
-        return count_masked_bytes(mask);
-}
 #endif
 
 #endif /* _ASM_WORD_AT_A_TIME_H */