sh: cmpxchg: fix a bit shift bug in big_endian os

commit ff18143ceed3424b7d6cdb8659b9692fa734f0d8 upstream.

Correct bitoff in big endian OS.
Current code works correctly for 1 byte but not for 2 bytes.

Fixes: 3226aad81aa6 ("sh: support 1 and 2 byte xchg")
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rich Felker <dalias@libc.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/sh/include/asm/cmpxchg-xchg.h b/arch/sh/include/asm/cmpxchg-xchg.h
index 7219719c23a3de54435544a207528ed4cf945287..1e881f5db6597a06bb0db787f4c105261f36ae98 100644 (file)
--- a/arch/sh/include/asm/cmpxchg-xchg.h
+++ b/arch/sh/include/asm/cmpxchg-xchg.h
@@ -21,7 +21,7 @@ static inline u32 __xchg_cmpxchg(volatile void *ptr, u32 x, int size)
        int off = (unsigned long)ptr % sizeof(u32);
        volatile u32 *p = ptr - off;
 #ifdef __BIG_ENDIAN
-       int bitoff = (sizeof(u32) - 1 - off) * BITS_PER_BYTE;
+       int bitoff = (sizeof(u32) - size - off) * BITS_PER_BYTE;
 #else
        int bitoff = off * BITS_PER_BYTE;
 #endif