BACKPORT: arm64: kasan: fix page_alloc tagging with DEBUG_VIRTUAL

When CONFIG_DEBUG_VIRTUAL is enabled, the default page_to_virt() macro
implementation from include/linux/mm.h is used. That definition doesn't
account for KASAN tags, which leads to no tags on page_alloc allocations.

Provide an arm64-specific definition for page_to_virt() when
CONFIG_DEBUG_VIRTUAL is enabled that takes care of KASAN tags.

Bug: 254441685
Fixes: 2813b9c02962 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc")
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/4b55b35202706223d3118230701c6a59749d9b72.1615219501.git.andreyknvl@google.com


Signed-off-by: Will Deacon <will@kernel.org>
(cherry picked from commit 86c83365ab76e4b43cedd3ce07a07d32a4dc79ba)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I9c0b6dd75da820cfa14dff4a70709ec1f119a9af