Kernel/aarch64: Store and initialize TTBR0_EL1 in ThreadRegisters

Author: https://github.com/FireFox317
Commit: https://github.com/SerenityOS/serenity/commit/1f30a5e4d9
Pull-request: https://github.com/SerenityOS/serenity/pull/16911
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/nico ✅

Kernel/Arch/aarch64/ThreadRegisters.h

@@ -15,15 +15,17 @@ struct ThreadRegisters {
     u64 x[31];
     u64 elr_el1;
     u64 sp_el0;
+    u64 ttbr0_el1;
 
     FlatPtr ip() const { return elr_el1; }
     void set_ip(FlatPtr value) { elr_el1 = value; }
 
     void set_sp(FlatPtr value) { sp_el0 = value; }
 
-    void set_initial_state(bool, Memory::AddressSpace&, FlatPtr kernel_stack_top)
+    void set_initial_state(bool, Memory::AddressSpace& space, FlatPtr kernel_stack_top)
     {
         set_sp(kernel_stack_top);
+        ttbr0_el1 = space.page_directory().ttbr0();
     }
 
     void set_entry_function(FlatPtr entry_ip, FlatPtr entry_data)