diff --git a/arch/riscv/include/asm/word-at-a-time.h b/arch/riscv/include/asm/word-at-a-time.h
index 3802cda71ab7ee..31240133eccdef 100644
--- a/arch/riscv/include/asm/word-at-a-time.h
+++ b/arch/riscv/include/asm/word-at-a-time.h
@@ -35,17 +35,57 @@ static inline unsigned long prep_zero_mask(unsigned long val,
 
 static inline unsigned long create_zero_mask(unsigned long bits)
 {
+	if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB) &&
+	    riscv_has_extension_likely(RISCV_ISA_EXT_ZBB))
+		return bits;
+
 	bits = (bits - 1) & ~bits;
 	return bits >> 7;
 }
 
+#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)
+{
+	return mask*0x0001020304050608ul >> 56;
+}
+
+#else	/* 32-bit case */
+
+/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
+static inline long count_masked_bytes(long mask)
+{
+	/* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
+	long a = (0x0ff0001+mask) >> 23;
+	/* Fix the 1 for 00 case */
+	return a & mask;
+}
+#endif
+
 static inline unsigned long find_zero(unsigned long mask)
 {
-	return fls64(mask) >> 3;
+	if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB) &&
+	    riscv_has_extension_likely(RISCV_ISA_EXT_ZBB))
+		return __ffs(mask) >> 3;
+
+	return count_masked_bytes(mask);
 }
 
-/* The mask we created is directly usable as a bytemask */
-#define zero_bytemask(mask) (mask)
+static inline unsigned long zero_bytemask(unsigned long bits)
+{
+	if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB) &&
+	    riscv_has_extension_likely(RISCV_ISA_EXT_ZBB)) {
+		bits = (bits - 1) & ~bits;
+		return bits >> 7;
+	}
+
+	return bits;
+}
 
 #ifdef CONFIG_DCACHE_WORD_ACCESS