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.

[andriy.shevchenko@linux.intel.com: convert infinite while loop to a for loop]
Link: http://lkml.kernel.org/r/20200609140535.87160-1-andriy.shevchenko@linux.intel.com
Fixes: 2d6261583be0 ("lib: rework bitmap_parse()")
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: Amritha Nambiar <amritha.nambiar@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: "Tobin C . Harding" <tobin@kernel.org>
Cc: Vineet Gupta <vineet.gupta1@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1591634471-17647-1-git-send-email-agordeev@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 21a7640..0364452 100644 (file)
--- 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);
        }