Hi Julien, > -----Original Message----- > Subject: [PATCH v6 3/5] xen/arm64: mm: Introduce helpers to > prepare/enable/disable the identity mapping > > From: Julien Grall <jgr...@amazon.com> > > In follow-up patches we will need to have part of Xen identity mapped in > order to safely switch the TTBR. > > On some platform, the identity mapping may have to start at 0. If we always > keep the identity region mapped, NULL pointer dereference would lead to > access to valid mapping. > > It would be possible to relocate Xen to avoid clashing with address 0. > However the identity mapping is only meant to be used in very limited > places. Therefore it would be better to keep the identity region invalid > for most of the time. > > Two new external helpers are introduced: > - arch_setup_page_tables() will setup the page-tables so it is > easy to create the mapping afterwards. > - update_identity_mapping() will create/remove the identity mapping > > Signed-off-by: Julien Grall <jgr...@amazon.com>
Reviewed-by: Henry Wang <henry.w...@arm.com> Kind regards, Henry
