aarch64: context: memory: Grant::map_inactive: Bugfix

When mapping one (from) virtual address range to another (to) virtual
address range, be mindful of which mapper type to use for each range.

Before this, the same mapper type was used for both ranges. This meant
that if from and to were different (as in not both kernel virtual
addresses or user virtual addresses) then it would appear that either
from or to was not mapped previously and the kernel would panic.

src/context/memory.rs

@@ -371,7 +371,7 @@ impl Grant {
     }
 
     pub fn map_inactive(from: VirtualAddress, to: VirtualAddress, size: usize, flags: EntryFlags, desc_opt: Option<FileDescriptor>, new_table: &mut InactivePageTable, temporary_page: &mut TemporaryPage) -> Grant {
-        let mut active_table = match to.get_type() {
+        let mut active_table = match from.get_type() {
             VirtualAddressType::User => unsafe { ActivePageTable::new(PageTableType::User) },
             VirtualAddressType::Kernel => unsafe { ActivePageTable::new(PageTableType::Kernel) }
         };
@@ -386,6 +386,11 @@ impl Grant {
             frames.push_back(frame);
         }
 
+        let mut active_table = match to.get_type() {
+            VirtualAddressType::User => unsafe { ActivePageTable::new(PageTableType::User) },
+            VirtualAddressType::Kernel => unsafe { ActivePageTable::new(PageTableType::Kernel) }
+        };
+
         active_table.with(new_table, temporary_page, |mapper| {
             let start_page = Page::containing_address(to);
             let end_page = Page::containing_address(VirtualAddress::new(to.data() + size - 1));