Increase kernel stack size to 2mb, move from cooperative to timer

preemption based scheduling, add correct save_lock on aarch64, add
simple IPC (read, write, manage), and simple and unsecure SHM, add
per-process kernel stacks, add copy_cstr_to_user, always use run_next
for aarch64, remove primitives from the kernel

kernel/src/task/process.rs

@@ -1,8 +1,10 @@
+use core::sync::atomic::Ordering;
+
 use alloc::vec::Vec;
 
 use crate::{
-    driver::io::keyboard::KeyboardEvent, mm::address_space::AddressSpace,
-    task::context::UserContext,
+    arch::arch::GLOBAL_TICK_COUNT, driver::io::keyboard::KeyboardEvent,
+    mm::address_space::AddressSpace, task::context::UserContext,
 };
 
 pub enum ProcessState {
@@ -22,13 +24,14 @@ pub struct Process {
     pub pid: u64,
     pub state: ProcessState,
     pub stack_top: u64,
+    pub kernel_stack_top: u64,
     pub heap_base: u64,
     pub heap_end: u64,
     pub kbd_buffer: Vec<KeyboardEvent>,
     pub address_space: Option<AddressSpace>,
     pub saved_ctx: Option<UserContext>,
-    pub should_reschedule: bool,
     pub user_entry: u64,
+    pub last_switch_tick: u64,
     pub info: ProcessInfo,
 }
 impl Process {
@@ -36,19 +39,21 @@ impl Process {
         pid: u64,
         user_entry: u64,
         stack_top: u64,
+        kernel_stack_top: u64,
         heap_base: u64,
         heap_end: u64,
     ) -> Process {
         Process {
             pid,
             stack_top,
+            kernel_stack_top,
             state: ProcessState::Ready,
             heap_base,
             heap_end,
+            last_switch_tick: GLOBAL_TICK_COUNT.load(Ordering::Relaxed),
             kbd_buffer: Vec::new(),
             address_space: None,
             saved_ctx: None,
-            should_reschedule: false,
             user_entry,
             info: ProcessInfo {
                 exit_code: 0,