microblaze: Fix bug with mmap2 syscall MB implementation

Fix mmap2 behaviour which incorrectly works with pgoff
not in 4k units.
Reported-by: Rich Felker <dalias@aerifal.cx>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/microblaze/kernel/sys_microblaze.c

@@ -42,3 +42,14 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
 
 	return sys_mmap_pgoff(addr, len, prot, flags, fd, pgoff >> PAGE_SHIFT);
 }
+
+SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
+		unsigned long, prot, unsigned long, flags, unsigned long, fd,
+		unsigned long, pgoff)
+{
+	if (pgoff & (~PAGE_MASK >> 12))
+		return -EINVAL;
+
+	return sys_mmap_pgoff(addr, len, prot, flags, fd,
+			      pgoff >> (PAGE_SHIFT - 12));
+}

arch/microblaze/kernel/syscall_table.S

@@ -192,7 +192,7 @@ ENTRY(sys_call_table)
 	.long sys_ni_syscall		/* reserved for streams2 */
 	.long sys_vfork		/* 190 */
 	.long sys_getrlimit
-	.long sys_mmap_pgoff		/* mmap2 */
+	.long sys_mmap2
 	.long sys_truncate64
 	.long sys_ftruncate64
 	.long sys_stat64		/* 195 */