【MOOC EXP】Linux内核分析实验二报告

/*
*linux/mykernel/mymain.c
*Kernelinternalmy_start_kernel
*Copyright(C)2013Mengning
*/
#include<linux/types.h>
#include<linux/string.h>
#include<linux/ctype.h>
#include<linux/tty.h>
#include<linux/vmalloc.h>

#include"mypcb.h"

tPCBtask[MAX_TASK_NUM];
tPCB*my_current_task=NULL;
volatileintmy_need_sched=0;//用来判断是否需要调度的标识

voidmy_process(void);

void__initmy_start_kernel(void)
{
intpid=0;
inti;
/*Initializeprocess0（初始化0号进程）*/
task[pid].pid=pid;
task[pid].state=0;/*-1unrunnable,0runnable,>0stopped*/
task[pid].task_entry=task[pid].thread.ip=(unsignedlong)my_process;//定义0号进程的入口：myprocess
task[pid].thread.sp=(unsignedlong)&task[pid].stack[KERNEL_STACK_SIZE-1];
task[pid].next=&task[pid];//由于0号进程初始化时只有这一个进程，所以next指向自己
/*forkmoreprocess（创建更多其他的进程）*/
for(i=1;i<MAX_TASK_NUM;i++)
{
memcpy(&task[i],&task[0],sizeof(tPCB));
task[i].pid=i;
task[i].state=-1;
task[i].thread.sp=(unsignedlong)&task[i].stack[KERNEL_STACK_SIZE-1];
task[i].next=task[i-1].next;
task[i-1].next=&task[i];
}
/*startprocess0bytask[0]*/
pid=0;
my_current_task=&task[pid];
asmvolatile(
//%0表示参数thread.ip，%1表示参数thread.sp。
"movl%1,%%esp\n\t"/*settask[pid].thread.sptoesp把参数thread.sp放到esp中*/
"pushl%1\n\t"/*pushebp由于当前栈是空的，esp与ebp指向相同，所以等价于pushebp*/
"pushl%0\n\t"/*pushtask[pid].thread.ip*/
"ret\n\t"/*poptask[pid].thread.iptoeip*/
"popl%%ebp\n\t"
:
:"c"(task[pid].thread.ip),"d"(task[pid].thread.sp)
/*inputcordmean%ecx/%edx*/
);
}
voidmy_process(void)
{
inti=0;
while(1)
{
i++;
if(i%10000000==0)
{
printk(KERN_NOTICE"thisisprocess%d-\n",my_current_task->pid);
if(my_need_sched==1)
{
my_need_sched=0;
my_schedule();
}
printk(KERN_NOTICE"thisisprocess%d+\n",my_current_task->pid);
}
}
}

my_start_kernelhere

/*
*linux/mykernel/myinterrupt.c
*Kernelinternalmy_timer_handler
*Copyright(C)2013Mengning
*/
#include<linux/types.h>
#include<linux/string.h>
#include<linux/ctype.h>
#include<linux/tty.h>
#include<linux/vmalloc.h>

#include"mypcb.h"

externtPCBtask[MAX_TASK_NUM];
externtPCB*my_current_task;
externvolatileintmy_need_sched;
volatileinttime_count=0;

/*
*Calledbytimerinterrupt.
*itrunsinthenameofcurrentrunningprocess,
*soitusekernelstackofcurrentrunningprocess
*/
voidmy_timer_handler(void)//用于设置时间片的大小，时间片用完时设置调度标志。
{
#if1
if(time_count%1000==0&&my_need_sched!=1)
{
printk(KERN_NOTICE">>>my_timer_handlerhere<<<\n");
my_need_sched=1;
}
time_count++;
#endif
return;
}

voidmy_schedule(void)
{
tPCB*next;
tPCB*prev;

if(my_current_task==NULL//task为空，即发生错误时返回
||my_current_task->next==NULL)
{
return;
}
printk(KERN_NOTICE">>>my_schedule<<<\n");
/*schedule*/
next=my_current_task->next;//把当前进程的下一个进程赋给next
prev=my_current_task;//当前进程为prev
if(next->state==0)/*-1unrunnable,0runnable,>0stopped*/
{
/*switchtonextprocess*/
/*如果下一个进程的状态是正在执行的话，就运用if语句中的代码表示的方法来切换进程*/
asmvolatile(
"pushl%%ebp\n\t"/*saveebp保存当前进程的ebp*/
"movl%%esp,%0\n\t"/*saveesp把当前进程的esp赋给%0（指的是thread.sp），即保存当前进程的esp*/
"movl%2,%%esp\n\t"/*restoreesp把%2（指下一个进程的sp）放入esp中*/
"movl$1f,%1\n\t"/*saveeip$1f是接下来的标号“1：”的位置，把eip保存下来*/
"pushl%3\n\t"/*把下一个进程eip压栈*/
"ret\n\t"/*restoreeip下一个进程开始执行*/
"1:\t"/*nextprocessstarthere*/
"popl%%ebp\n\t"
:"=m"(prev->thread.sp),"=m"(prev->thread.ip)
:"m"(next->thread.sp),"m"(next->thread.ip)
);
my_current_task=next;
printk(KERN_NOTICE">>>switch%dto%d<<<\n",prev->pid,next->pid);
}
else//用于下一个进程为未执行过的新进程时。首先将这个进程置为运行时状态，将这个进程作为当前正在执行的进程。
{
next->state=0;
my_current_task=next;
printk(KERN_NOTICE">>>switch%dto%d<<<\n",prev->pid,next->pid);
/*switchtonewprocess*/
asmvolatile(
"pushl%%ebp\n\t"/*saveebp*/
"movl%%esp,%0\n\t"/*saveesp*/
"movl%2,%%esp\n\t"/*restoreesp*/
"movl%2,%%ebp\n\t"/*restoreebp*/
"movl$1f,%1\n\t"/*saveeip*/
"pushl%3\n\t"/*把当前进程的入口保存起来*/
"ret\n\t"/*restoreeip*/
:"=m"(prev->thread.sp),"=m"(prev->thread.ip)
:"m"(next->thread.sp),"m"(next->thread.ip)
);
}
return;
}