new: vma反向映射

kernel/common/semaphore.c

@@ -0,0 +1,43 @@
+#include "semaphore.h"
+#include <sched/sched.h>
+#include <process/process.h>
+
+
+void semaphore_down(semaphore_t *sema)
+{
+    if (atomic_read(&sema->counter) > 0) // 信号量大于0，资源充足
+        atomic_dec(&sema->counter);
+    else // 资源不足，进程休眠
+    {
+        // 将当前进程加入信号量的等待队列
+        wait_queue_node_t wait;
+        wait_queue_init(&wait, current_pcb);
+
+        current_pcb->state = PROC_UNINTERRUPTIBLE;
+
+        list_append(&sema->wait_queue.wait_list, &wait.wait_list);
+
+        // 执行调度
+        sched_cfs();
+    }
+}
+
+void semaphore_up(semaphore_t *sema)
+{
+    if (list_empty(&sema->wait_queue.wait_list)) // 没有进程在等待资源
+    {
+        atomic_inc(&sema->counter);
+    }
+    else    // 有进程在等待资源，唤醒进程
+    {
+
+        wait_queue_node_t *wq = container_of(list_next(&sema->wait_queue.wait_list), wait_queue_node_t, wait_list);
+        list_del(&wq->wait_list);
+
+        wq->pcb->state = PROC_RUNNING;
+        sched_cfs_enqueue(wq->pcb);
+
+        // 当前进程缺少需要的资源，立即标为需要被调度
+        current_pcb->flags |= PF_NEED_SCHED;
+    }
+};