Support signal mechanism for ch8(only works on signal-thread apps)

os/src/task/manager.rs

@@ -1,6 +1,6 @@
-use super::TaskControlBlock;
+use super::{ProcessControlBlock, TaskControlBlock};
 use crate::sync::UPSafeCell;
-use alloc::collections::VecDeque;
+use alloc::collections::{BTreeMap, VecDeque};
 use alloc::sync::Arc;
 use lazy_static::*;
 
@@ -26,6 +26,8 @@ impl TaskManager {
 lazy_static! {
     pub static ref TASK_MANAGER: UPSafeCell<TaskManager> =
         unsafe { UPSafeCell::new(TaskManager::new()) };
+    pub static ref PID2PCB: UPSafeCell<BTreeMap<usize, Arc<ProcessControlBlock>>> =
+        unsafe { UPSafeCell::new(BTreeMap::new()) };
 }
 
 pub fn add_task(task: Arc<TaskControlBlock>) {
@@ -35,3 +37,19 @@ pub fn add_task(task: Arc<TaskControlBlock>) {
 pub fn fetch_task() -> Option<Arc<TaskControlBlock>> {
     TASK_MANAGER.exclusive_access().fetch()
 }
+
+pub fn pid2process(pid: usize) -> Option<Arc<ProcessControlBlock>> {
+    let map = PID2PCB.exclusive_access();
+    map.get(&pid).map(|task| Arc::clone(task))
+}
+
+pub fn insert_into_pid2process(pid: usize, process: Arc<ProcessControlBlock>) {
+    PID2PCB.exclusive_access().insert(pid, process);
+}
+
+pub fn remove_from_pid2process(pid: usize) {
+    let mut map = PID2PCB.exclusive_access();
+    if map.remove(&pid).is_none() {
+        panic!("cannot find pid {} in pid2task!", pid);
+    }
+}