1 /*2  *  linux/mykernel/myinterrupt.c3  *4  *  Kernel internal my_timer_handler5  *6  *  Copyright (C) 2013  Mengning7  *8  */9 #include <linux/types.h>
10 #include <linux/string.h>
11 #include <linux/ctype.h>
12 #include <linux/tty.h>
13 #include <linux/vmalloc.h>
14
15 #include "mypcb.h"
16
17 extern tPCB task[MAX_TASK_NUM];
18 extern tPCB * my_current_task;
19 extern volatile int my_need_sched;  //进程是否需要调度的标志
20 volatile int time_count = 0;
21
22 /*
23  * Called by timer interrupt.
24  * it runs in the name of current running process,
25  * so it use kernel stack of current running process
26  */
27 void my_timer_handler(void)
28 {
29 #if 1
30     if(time_count%1000 == 0 && my_need_sched != 1)
31     {
32         printk(KERN_NOTICE ">>>my_timer_handler here<<<\n");
33         my_need_sched = 1;
34     }
35     time_count ++ ;
36 #endif
37     return;
38 }
39
40 void my_schedule(void)
41 {
42     tPCB * next;
43     tPCB * prev;
44
45     if(my_current_task == NULL
46         || my_current_task->next == NULL)
47     {
48         return;
49     }
50     printk(KERN_NOTICE ">>>my_schedule<<<\n");
51     /* schedule */
52     next = my_current_task->next;
53     prev = my_current_task;
54     if(next->state == 0)/* -1 unrunnable, 0 runnable, >0 stopped */
55     {
56         /* switch to next process */
57         asm volatile(
58             "pushl %%ebp\n\t"
59             "movl %%esp,%0\n\t"     /*将进程的task[pid].thread.sp，就是esp赋给esp寄存器*/　　　　
60             "movl %2,%%esp\n\t"
61             "movl $1f,%1\n\t"
62             "pushl %3\n\t" 　　　　　　/*ebp入栈：因为在这里栈为空，esp==ebp，所以push的%3就是esp就是ebp*/
63             "ret\n\t"                 /*把进程入口task[pid].thread.ip赋给eip，即从这之后0号进程启动*/
64             "1:\t"                  /* next process start here */
65             "popl %%ebp\n\t"
66             : "=m" (prev->thread.sp),"=m" (prev->thread.ip)
67             : "m" (next->thread.sp),"m" (next->thread.ip)
68         );
69         my_current_task = next;
70         printk(KERN_NOTICE ">>>switch %d to %d<<<\n",prev->pid,next->pid);
71     }
72     else
73     {
74         next->state = 0;
75         my_current_task = next;
76         printk(KERN_NOTICE ">>>switch %d to %d<<<\n",prev->pid,next->pid);
77         /* switch to new process */
78         asm volatile(
79             "pushl %%ebp\n\t"         /* save ebp */
80             "movl %%esp,%0\n\t"     /* save esp */
81             "movl %2,%%esp\n\t"     /* restore  esp */
82             "movl %2,%%ebp\n\t"     /* restore  ebp */
83             "movl $1f,%1\n\t"       /* save eip */
84             "pushl %3\n\t"
85             "ret\n\t"                 /* restore  eip */
86             : "=m" (prev->thread.sp),"=m" (prev->thread.ip)
87             : "m" (next->thread.sp),"m" (next->thread.ip)
88         );
89     }
90     return;
91 }

1 /*2  *  linux/mykernel/mypcb.h3  *4  *  Kernel internal PCB types5  *6  *  Copyright (C) 2013  Mengning7  *8  */9
10 #define MAX_TASK_NUM        4
11 #define KERNEL_STACK_SIZE   1024*8
12
13 /* CPU-specific state of this task */
14 struct Thread {
15     unsigned long        ip;
16     unsigned long        sp;　　　　/*存储ip和sp*/
17 };
18
19 typedef struct PCB{
20     int pid;　　　　　　　　　　/*进程id*/
21     volatile long state;    /* -1 unrunnable, 0 runnable, >0 stopped 进程状态*/
22     char stack[KERNEL_STACK_SIZE];　　　　/*进程堆栈*/ 23 /* CPU-specific state of this task */ 24 struct Thread thread; 25 unsigned long task_entry; 26 struct PCB *next; 27 }tPCB; 28 29 void my_schedule(void);