Murmurhash byteswapping fix v2 [VDO-5720]

Per suggestion from Eric Biggers on dm-devel, don't use cpu_to_le64
and friends, use get_unaligned_le64 and friends. Call them directly
rather than via a wrapper function, since we don't need the
conditional mess. Use the same code for user mode, as well.

Signed-off-by: Matthew Sakai <[email protected]>

drivers/md/dm-vdo/murmurhash3.c

@@ -8,23 +8,14 @@
 
 #include "murmurhash3.h"
 
-#include <asm/byteorder.h>
+#include <asm/unaligned.h>
 
 static inline u64 rotl64(u64 x, s8 r)
 {
 	return (x << r) | (x >> (64 - r));
 }
 
 #define ROTL64(x, y) rotl64(x, y)
-static __always_inline u64 getblock64(const u64 *p, int i)
-{
-	return le64_to_cpup(&p[i]);
-}
-
-static __always_inline void putblock64(u64 *p, int i, u64 value)
-{
-	p[i] = cpu_to_le64(value);
-}
 
 /* Finalization mix - force all bits of a hash block to avalanche */
 
@@ -50,15 +41,17 @@ void murmurhash3_128(const void *key, const int len, const u32 seed, void *out)
 	const u64 c1 = 0x87c37b91114253d5LLU;
 	const u64 c2 = 0x4cf5ad432745937fLLU;
 
+	u64 *hash_out = out;
+
 	/* body */
 
 	const u64 *blocks = (const u64 *)(data);
 
 	int i;
 
 	for (i = 0; i < nblocks; i++) {
-		u64 k1 = getblock64(blocks, i * 2 + 0);
-		u64 k2 = getblock64(blocks, i * 2 + 1);
+		u64 k1 = get_unaligned_le64(&blocks[i * 2]);
+		u64 k2 = get_unaligned_le64(&blocks[i * 2 + 1]);
 
 		k1 *= c1;
 		k1 = ROTL64(k1, 31);
@@ -160,6 +153,6 @@ void murmurhash3_128(const void *key, const int len, const u32 seed, void *out)
 	h1 += h2;
 	h2 += h1;
 
-	putblock64((u64 *)out, 0, h1);
-	putblock64((u64 *)out, 1, h2);
+	put_unaligned_le64(h1, &hash_out[0]);
+	put_unaligned_le64(h2, &hash_out[1]);
 }