From 08fd5cee6b44a27d9ded1dbc215710c214a1b2c6 Mon Sep 17 00:00:00 2001
From: mmhong <m202372126@hust.edu.cn>
Date: Thu, 24 Oct 2024 14:48:55 +0800
Subject: [PATCH] over sir!

---
 os/src/mm/memory_set.rs   |  9 ++++++---
 os/src/mm/page_table.rs   |  6 +++---
 os/src/syscall/process.rs |  6 +++---
 os/src/task/mod.rs        | 28 +++++++++++++++++++++++++++-
 4 files changed, 39 insertions(+), 10 deletions(-)

diff --git a/os/src/mm/memory_set.rs b/os/src/mm/memory_set.rs
index 7a7b7eae..e54ee02b 100644
--- a/os/src/mm/memory_set.rs
+++ b/os/src/mm/memory_set.rs
@@ -35,8 +35,10 @@ lazy_static! {
 }
 /// address space
 pub struct MemorySet {
-    page_table: PageTable,
-    areas: Vec<MapArea>,
+    /// page table
+    pub page_table: PageTable,
+    /// map areas
+    pub areas: Vec<MapArea>,
 }
 
 impl MemorySet {
@@ -265,7 +267,8 @@ impl MemorySet {
 }
 /// map area structure, controls a contiguous piece of virtual memory
 pub struct MapArea {
-    vpn_range: VPNRange,
+    /// virtual page number range
+    pub vpn_range: VPNRange,
     data_frames: BTreeMap<VirtPageNum, FrameTracker>,
     map_type: MapType,
     map_perm: MapPermission,
diff --git a/os/src/mm/page_table.rs b/os/src/mm/page_table.rs
index 525f8769..48b50429 100644
--- a/os/src/mm/page_table.rs
+++ b/os/src/mm/page_table.rs
@@ -121,13 +121,13 @@ impl PageTable {
         let mut result: Option<&mut PageTableEntry> = None;
         for (i, idx) in idxs.iter().enumerate() {
             let pte = &mut ppn.get_pte_array()[*idx];
+            if !pte.is_valid() {
+                return None;
+            }
             if i == 2 {
                 result = Some(pte);
                 break;
             }
-            if !pte.is_valid() {
-                return None;
-            }
             ppn = pte.ppn();
         }
         result
diff --git a/os/src/syscall/process.rs b/os/src/syscall/process.rs
index 8604936e..4f02e54c 100644
--- a/os/src/syscall/process.rs
+++ b/os/src/syscall/process.rs
@@ -2,7 +2,7 @@
 use crate::{
     config::MAX_SYSCALL_NUM,
     task::{
-        task_mmap_area,get_current_task_info,current_user_token,change_program_brk, exit_current_and_run_next, suspend_current_and_run_next, TaskStatus,
+        task_munmap_area,task_mmap_area,get_current_task_info,current_user_token,change_program_brk, exit_current_and_run_next, suspend_current_and_run_next, TaskStatus,
     },
     mm::{MapPermission,translated_byte_buffer},
 };
@@ -99,8 +99,8 @@ pub fn sys_mmap(_start: usize, _len: usize, _prot: usize) -> isize {
 
 // YOUR JOB: Implement munmap.
 pub fn sys_munmap(_start: usize, _len: usize) -> isize {
-    trace!("kernel: sys_munmap NOT IMPLEMENTED YET!");
-    -1
+    trace!("kernel: sys_munmap");
+    task_munmap_area(_start, _len)
 }
 /// change data segment size
 pub fn sys_sbrk(size: i32) -> isize {
diff --git a/os/src/task/mod.rs b/os/src/task/mod.rs
index 90353e1e..c2eba54e 100644
--- a/os/src/task/mod.rs
+++ b/os/src/task/mod.rs
@@ -190,10 +190,32 @@ impl TaskManager {
         let memory_set = &mut task.memory_set;
         //传入虚拟内存地址，之后调用的函数会自动转换为页号，向下向上取整
         let start_va = VirtAddr::from(_start);
-        let end_va = VirtAddr::from(_start + _len-1);//注意这个地方是减一
+        let end_va = VirtAddr::from(_start + _len);//注意这个地方是减一
         memory_set.insert_framed_area(start_va,end_va, _permission);
         0
     }
+    fn task_munmap_area(&self,_start:usize,_len:usize)->isize{
+        let mut inner = self.inner.exclusive_access();
+        let current = inner.current_task;
+        let task = &mut inner.tasks[current];//控制块
+        let memory_set = &mut task.memory_set;//其areas字段私有，只能通过控制块访问,修改为pub
+        let mut area_id = 0;
+        let page_table =&mut memory_set.page_table;
+        for area in memory_set.areas.iter_mut(){
+            // println!("vpn_range start:{:?} end:{:?}",area.vpn_range.get_start().0,area.vpn_range.get_end().0);
+            // println!("start:{:?} end:{:?}",_start/4096,(_start+_len)/4096);
+            if area.vpn_range.get_start().0*4096 == _start && area.vpn_range.get_end().0*4096 == _start+_len{
+                // println!("find area");
+                area.unmap(page_table);
+                // println!("find area");
+                memory_set.areas.remove(area_id);
+                // println!("find area");
+                return 0;
+            }
+            area_id += 1;
+        }
+        -1
+    }
 }
 
 /// Run the first task in task list.
@@ -258,3 +280,7 @@ pub fn increase_current_syscall_count(syscall_id: usize) {
 pub fn task_mmap_area(_start:usize,_len:usize,permission:MapPermission)->isize{
     TASK_MANAGER.task_mmap_area(_start,_len,permission)
 }
+///task_munmap_area
+pub fn task_munmap_area(_start:usize,_len:usize)->isize{
+    TASK_MANAGER.task_munmap_area(_start,_len)
+}
\ No newline at end of file