lib: fix bitmap_parse() on 64-bit big endian archs

Commit 2d6261583be0 ("lib: rework bitmap_parse()") does not take into
account order of halfwords on 64-bit big endian architectures.  As
result (at least) Receive Packet Steering, IRQ affinity masks and
runtime kernel test "test_bitmap" get broken on s390.

[[email protected]: convert infinite while loop to a for loop]
  Link: http://lkml.kernel.org/r/[email protected]

Fixes: 2d6261583be0 ("lib: rework bitmap_parse()")
Signed-off-by: Alexander Gordeev <[email protected]>
Signed-off-by: Andy Shevchenko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Cc: Yury Norov <[email protected]>
Cc: Amritha Nambiar <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Miklos Szeredi <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Steffen Klassert <[email protected]>
Cc: "Tobin C . Harding" <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Willem de Bruijn <[email protected]>
Cc: <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 7 insertions, 2 deletions

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 21a7640c5eed..0364452b1617 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -741,8 +741,9 @@ int bitmap_parse(const char *start, unsigned int buflen,
 	int chunks = BITS_TO_U32(nmaskbits);
 	u32 *bitmap = (u32 *)maskp;
 	int unset_bit;
+	int chunk;
 
-	while (1) {
+	for (chunk = 0; ; chunk++) {
 		end = bitmap_find_region_reverse(start, end);
 		if (start > end)
 			break;
@@ -750,7 +751,11 @@ int bitmap_parse(const char *start, unsigned int buflen,
 		if (!chunks--)
 			return -EOVERFLOW;
 
-		end = bitmap_get_x32_reverse(start, end, bitmap++);
+#if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN)
+		end = bitmap_get_x32_reverse(start, end, &bitmap[chunk ^ 1]);
+#else
+		end = bitmap_get_x32_reverse(start, end, &bitmap[chunk]);
+#endif
 		if (IS_ERR(end))
 			return PTR_ERR(end);
 	}