arm64: fix types in copy_highpage()

In copy_highpage() the `kto` and `kfrom` local variables are pointers to
struct page, but these are used to hold arbitrary pointers to kernel memory
. Each call to page_address() returns a void pointer to memory associated
with the relevant page, and copy_page() expects void pointers to this
memory.

This inconsistency was introduced in commit 2563776 ("arm64: mte:
Tags-aware copy_{user_,}highpage() implementations") and while this
doesn't appear to be harmful in practice it is clearly wrong.

Correct this by making `kto` and `kfrom` void pointers.

Fixes: 2563776 ("arm64: mte: Tags-aware copy_{user_,}highpage() implementations")
Signed-off-by: Tong Tiangen <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Reviewed-by: Kefeng Wang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

Author: Tong Tiangen

arch/arm64/mm/copypage.c

@@ -16,8 +16,8 @@
 
 void copy_highpage(struct page *to, struct page *from)
 {
-	struct page *kto = page_address(to);
-	struct page *kfrom = page_address(from);
+	void *kto = page_address(to);
+	void *kfrom = page_address(from);
 
 	copy_page(kto, kfrom);