Re: [PATCH v15 07/17] mm, arm64: untag user pointers in mm/gup.c

On Mon, May 06, 2019 at 06:30:53PM +0200, Andrey Konovalov wrote:

This patch is a part of a series that extends arm64 kernel ABI to allow to pass tagged user pointers (with the top byte set to something else other than 0x00) as syscall arguments.

mm/gup.c provides a kernel interface that accepts user addresses and manipulates user pages directly (for example get_user_pages, that is used by the futex syscall). Since a user can provided tagged addresses, we need to handle this case.

Add untagging to gup.c functions that use user addresses for vma lookups.

Signed-off-by: Andrey Konovalov andreyknvl@google.com

Reviewed-by: Catalin Marinas catalin.marinas@arm.com