binder: Use kmap_local_page() in binder_alloc_copy_user_to_buffer()

The use of kmap() is being deprecated in favor of kmap_local_page()
where it is feasible. With kmap_local_page(), the mapping is per
thread, CPU local and not globally visible.

binder_alloc_copy_user_to_buffer() is a function where the use of
kmap_local_page() in place of kmap() is correctly suited because
the mapping is local to the thread.

Therefore, use kmap_local_page() / kunmap_local().

Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20220425175754.8180-3-fmdefrancesco@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 0b3f2f569053c4fb13ef475a7ad6ceb3e7507b15..0875c463c002ac66eb31a37ec6f6a5b92a0a4c98 100644 (file)
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -1217,9 +1217,9 @@ binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
                page = binder_alloc_get_page(alloc, buffer,
                                             buffer_offset, &pgoff);
                size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
-               kptr = kmap(page) + pgoff;
+               kptr = kmap_local_page(page) + pgoff;
                ret = copy_from_user(kptr, from, size);
-               kunmap(page);
+               kunmap_local(kptr);
                if (ret)
                        return bytes - size + ret;
                bytes -= size;