修改Linux内核，添加系统调用，输出CPU等信息到屏幕上，调整printk打印级别没有用处，使用tty结构体的ops中的write函数，在测试中，运行测试代码就会卡在界面啥也出不来，重启之后运行测试代码啥也不显示，代码如下

Question

Linux内核版本：4.15.1
Ubuntu版本：16.04
虚拟机版本：14
以下是系统调用部分的代码：
错误是在打印进程信息那里，其他同学也是使用这个函数，都可以通过测试代码，我把使用tty部分注释掉就没有问题

asmlinkage long sys_hello_world(char *A,char *B)
{
    struct file *fp;
    mm_segment_t fs;
    loff_t pos;
    struct task_struct *p;
    struct tty_struct *q;

    char buf1[42]={"\0"};
    char buf2[78]={"\0"};
//将CPU信息送到数组A
    fp=filp_open("/proc/cpuinfo",O_RDONLY,0);
    fs=get_fs();
    set_fs(KERNEL_DS);
    pos=79;
    vfs_read(fp,buf1,sizeof(buf1),&pos);
    buf1[41]='\0';
    copy_to_user(A,buf1,42);
    filp_close(fp,NULL);
    set_fs(fs);
//将版本信息送到数组B
    fp=filp_open("/proc/version",O_RDONLY,0);
    fs=get_fs();
    set_fs(KERNEL_DS);
    pos=0;
    vfs_read(fp,buf2,sizeof(buf2),&pos);
    copy_to_user(B,buf2,78);
    filp_close(fp,NULL);
    set_fs(fs);
//打印进程相关信息
    q=current->signal->tty;
    char correct[20]={"\0"};
    char printScreen[80]={"\0"};

    q->ops->write(q,"**************process        information***********",42);
    q->ops->write(q,"\n\r",2);
    sprintf(printScreen,"%-20s %-20s %-20s %-20s","Name","pid","State","ParentName");
    q->ops->write(q,printScreen,sizeof(printScreen));
    q->ops->write(q,"\n\r",2);

    for(p=&init_task;(p=next_task(p))!=&init_task; )
    {
        sprintf(correct,"%-20s",p->comm);
        q->ops->write(q,correct,sizeof(correct));
        sprintf(correct,"%-20s",p->pid);
        q->ops->write(q,correct,sizeof(correct));
        sprintf(correct,"%-20s",p->state);
        q->ops->write(q,correct,sizeof(correct));
        sprintf(correct,"%-20s",p->parent->comm);
        q->ops->write(q,correct,sizeof(correct));

        q->ops->write(q,"\n\r",2);
    }
    q->ops->write(q,"\n\r",2);
    return 0;
}

以下是我个人的测试代码：
我设计的系统调用号为666

#include <stdio.h>
#include <linux/unistd.h>

int main()
{
    char A[42]={"\0"};
    char B[78]={"\0"};

    syscall(666,A,B);
    printf("\n");
    printf("*********the   cpu   info**********\n");
    printf("%s\n",A);
    printf("*********the version info**********\n");
    printf("%s\n",B);
    printf("*************end*******************\n");

    return 0;
}

求好心大佬帮助，tty卡在这里是为啥，没充值c币，可微信支付宝感谢

Answer 1

https://blog.csdn.net/baidu_31504167/article/details/94455088