lib/bitmap: drop optimization of bitmap_{from,to}_arr64

bitmap_{from,to}_arr64() optimization is overly optimistic on 32-bit LE
architectures when it's wired to bitmap_copy_clear_tail().

bitmap_copy_clear_tail() takes care of unused bits in the bitmap up to
the next word boundary. But on 32-bit machines when copying bits from
bitmap to array of 64-bit words, it's expected that the unused part of
a recipient array must be cleared up to 64-bit boundary, so the last 4
bytes may stay untouched when nbits % 64 <= 32.

While the copying part of the optimization works correct, that clear-tail
trick makes corresponding tests reasonably fail:

test_bitmap: bitmap_to_arr64(nbits == 1): tail is not safely cleared: 0xa5a5a5a500000001 (must be 0x0000000000000001)

Fix it by removing bitmap_{from,to}_arr64() optimization for 32-bit LE
arches.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/lkml/20230225184702.GA3587246@roeck-us.net/
Fixes: 0a97953fd221 ("lib: add bitmap_{from,to}_arr64")
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 1c81413c51f8..ddb31015e38a 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -1495,7 +1495,7 @@ void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits)
 EXPORT_SYMBOL(bitmap_to_arr32);
 #endif
 
-#if (BITS_PER_LONG == 32) && defined(__BIG_ENDIAN)
+#if BITS_PER_LONG == 32
 /**
  * bitmap_from_arr64 - copy the contents of u64 array of bits to bitmap
  *	@bitmap: array of unsigned longs, the destination bitmap