From a0c6239d1e83240ba931fe419e1e2e980de0ee41 Mon Sep 17 00:00:00 2001
From: forever-learner <2360561713@qq.com>
Date: Fri, 1 Jul 2022 00:31:40 +0800
Subject: [PATCH] final version of munmap

---
 linux/kernel/exit.c | 12 ++++++++++--
 linux/mm/memory.c   | 17 +++++++++++------
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/linux/kernel/exit.c b/linux/kernel/exit.c
index 2406ebe..839737c 100644
--- a/linux/kernel/exit.c
+++ b/linux/kernel/exit.c
@@ -15,7 +15,7 @@
 
 int sys_pause(void);
 int sys_close(int fd);
-
+extern int sys_munmap(void * start ,size_t size);
 void release(struct task_struct * p)
 {
 	int i;
@@ -102,7 +102,15 @@ static void tell_father(int pid)
 int do_exit(long code)
 {
 	int i;
-
+	struct mmap_struct *temp=current->mmap;
+	while(temp)
+	{
+		printk("%x\n.",temp->address);
+		printk("%x\n.",temp->endaddr);
+		printk("%d\n.",temp->next);
+		sys_munmap((void *)temp->address,temp->size);
+		temp=temp->next;
+	}
 	free_page_tables(get_base(current->ldt[1]),get_limit(0x0f));
 	free_page_tables(get_base(current->ldt[2]),get_limit(0x17));
 	for (i=0 ; i<NR_TASKS ; i++)
diff --git a/linux/mm/memory.c b/linux/mm/memory.c
index ca1af58..e7f6a52 100644
--- a/linux/mm/memory.c
+++ b/linux/mm/memory.c
@@ -625,7 +625,7 @@ long sys_mmap(void * start,size_t len,...)// int prot,int flags,int fd,off_t off
 				*(unsigned long *)from_page= tpage | 7; 
 				mem_map[(tpage-LOW_MEM)>>12]++;
 			}
-		*(unsigned long *)from_page &= (prot&PROT_WRITE); //分配读写权限
+		*(unsigned long *)from_page &= (prot&PROT_WRITE)?0xffffffff:0xfffffffd; //分配读写权限
 		
 		if(flags & MAP_SHARED)
 		{
@@ -709,9 +709,9 @@ int sys_munmap(void * start ,size_t size)
 	if(!pre)
 	{
 		if(current->mmap_tail==current->mmap)current->mmap_tail=NULL;
-		current->mmap==current->mmap->next;
+		current->mmap=current->mmap->next;
 	}
-	if(temp->next=NULL)
+	else if(temp->next=NULL)
 	{
 		current->mmap_tail=pre;
 		pre->next=NULL;
@@ -726,12 +726,13 @@ int sys_munmap(void * start ,size_t size)
 	unsigned long phys_addr;
 	unsigned long tpage;
 	unsigned long address=temp->address;
+	printk("%lx\n",address);
 	if(!(temp->ps & MAP_SHARED))
 		goto mytag;
 	//若为共享，执行下面的代码
 	while (address < temp ->endaddr)
 	{
-		printk("addr: %lx\n",address);
+		//printk("addr: %lx\n",address);
 		from_page =  ((address>>20) & 0xffc);
 		from_page += ((current->start_code>>20) & 0xffc);//页目录
 		from=*(unsigned long *)from_page;	//页表项
@@ -741,7 +742,8 @@ int sys_munmap(void * start ,size_t size)
 		//printk("addr: %lx",*(unsigned long *)from_page);
 		if(!(*(unsigned long *)from_page & 1))
 		{
-			printk("error of deleting page.");
+			printk("error of deleting page at %x.\n",*(unsigned long *)from_page);
+			printk("current address:%x\n",address);
 			return -1;
 		}
 		if(temp->ps & MAP_SHARED)
@@ -778,8 +780,10 @@ int sys_munmap(void * start ,size_t size)
 	}
 mytag:
 	//取消物理页写权限
+	address=temp->address;
 	while (address < temp ->endaddr)
 	{
+		//printk("%lx\n",address);
 		from_page =  ((address>>20) & 0xffc);
 		from_page += ((current->start_code>>20) & 0xffc);//页目录
 		from=*(unsigned long *)from_page;	//页表项
@@ -789,7 +793,8 @@ mytag:
 		//printk("addr: %lx",*(unsigned long *)from_page);
 		if(!(*(unsigned long *)from_page & 1))
 		{
-			printk("error of deleting page.");
+			printk("error of deleting page at %x.\n",*(unsigned long *)from_page);
+			printk("current address:%x\n",address);
 			return -1;
 		}
 		else{