IOCTL写崩溃

Question

我试图在内核空间中实现ioctl，以便将一些日期写入寄存器，在cmd的ioctl中我会崩溃。

下面是我的代码：

内核端：

static struct file_operations fops = {
.compat_ioctl = device_ioctl
};

int device_ioctl(struct inode *inode, struct file *filep, 
                 unsigned int cmd, unsigned long arg)
{

    int len = 200;

    printk (KERN_INFO "In Device_ioctl !!\n");
    switch(cmd)
    {
    case IOCTL_WRITE_REG:
        write_ioctl((unsigned long *)arg);
        break;

    default:
        printk (KERN_INFO "default\n");
        return -ENOTTY;
    }
    printk (KERN_INFO "device_ioctl out\n");
    return len;
}

用户端

#define IOCTL_WRITE_REG _IOW(MAJOR_NUM, 1, int *)
void write_to_device(int write_fd)
{

    int retval;
    unsigned int to_write1 = 1;

    retval = ioctl(write_fd, IOCTL_WRITE_REG, &to_write1);
    if(retval < 0)
    {
        printf("fd: %d, write error: %d\n", write_fd, errno);
        exit(-1);
    }
}

它没有进入device_ioctl函数，我哪里出错了？

Answer 1

有几件事我碰巧注意到：

• 您需要使用unlocked_ioctl而不是compat_ioctl。compat_ioctl允许32位用户空间程序在64位内核上调用ioctl调用.
• ioctl处理程序函数的签名不正确(对于unlocked_ioctl)。预期的签名是： long (*unlocked_ioctl) (struct * filep，unsigned，unsigned )；

我还没有真正地编译这段代码，但我认为这应该是可行的：

static struct file_operations fops = {
    .unlocked_ioctl = device_ioctl
};

long device_ioctl(struct file *filep, 
                  unsigned int cmd,
                  unsigned long arg)
{

    int len = 200;

    printk (KERN_INFO "In Device_ioctl !!\n");
    switch(cmd)
    {
    case IOCTL_WRITE_REG:
        write_ioctl((unsigned long *)arg);
        break;

    default:
        printk (KERN_INFO "default\n");
        return -ENOTTY;
    }
    printk (KERN_INFO "device_ioctl out\n");
    return len;
}