On 16/04/2023 16:32, Julien Grall wrote: > > > 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: Michal Orzel <michal.or...@amd.com>
~Michal
