0 准备工作。
0.0 系统环境：Ubuntu18.04.1 amd64。
0.1 安装必要软件包
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sudo apt install build-essential bison flex libssl-dev libelf-dev
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1 下载内核源码，构建源码树
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sudo apt install linux-source-4.15.0 -y
cd /usr/src/linux-source-4.15.0/
sudo tar xf linux-source-4.15.0.tar.bz2
cd linux-source-4.15.0/
sudo make oldconfig
sudo make prepare
sudo make scripts
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2 编译驱动源码
源码需要改动几处：
copy_to_user()改为raw_copy_to_user();
copy_from_user()改为raw_copy_from_user();
init_MUTEX((&scull_device->sem);改为sema_init(&scull_device->sem, 1);
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makesudo insmod scull.ko
sudo rmmod scull.ko
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附1：scull.c
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#include <linux/init.h>#include <linux/module.h>#include <linux/fs.h>#include <linux/slab.h>#include <linux/errno.h>#include <linux/types.h>#include <linux/cdev.h>#include <asm/uaccess.h>#include "scull.h"int scull_major = SCULL_MAJOR;
int scull_minor = 0;
module_param(scull_major, int, S_IRUGO);
module_param(scull_minor, int, S_IRUGO);
struct scull_dev *scull_device;
int scull_trim(struct scull_dev *dev)
{ if (dev)
{
if (dev->data)
{
kfree(dev->data);
}
dev->data = NULL;
dev->size = 0;
}
return 0;
}int scull_open(struct inode *inode, struct file *filp)
{ struct scull_dev *dev;
dev = container_of(inode->i_cdev, struct scull_dev, cdev);
filp->private_data = dev;
if ((filp->f_flags & O_ACCMODE) == O_WRONLY)
{
if (down_interruptible(&dev->sem))
{
return -ERESTARTSYS;
}
scull_trim(dev);
up(&dev->sem);
}
return 0;
}int scull_release(struct inode *inode, struct file *filp)
{ return 0;
}ssize_t scull_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{ struct scull_dev *dev = filp->private_data;
ssize_t retval = 0;
if (down_interruptible(&dev->sem))
{
return -ERESTARTSYS;
}
if (*f_pos >= dev->size)
{
goto out;
}
if (*f_pos + count > dev->size)
{
count = dev->size - *f_pos;
}
if (!dev->data)
{
goto out;
}
if (raw_copy_to_user(buf, dev->data + *f_pos, count))
{
retval = -EFAULT;
goto out;
}
*f_pos += count;
retval = count;
out:
up(&dev->sem);
return retval;
}ssize_t scull_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos)
{ struct scull_dev *dev = filp->private_data;
ssize_t retval = -ENOMEM;
if (down_interruptible(&dev->sem))
{
return -ERESTARTSYS;
}
if (!dev->data)
{
dev->data = kmalloc(SCULL_BUFFER_SIZE, GFP_KERNEL);
if (!dev->data)
{
goto out;
}
memset(dev->data, 0, SCULL_BUFFER_SIZE);
}
if (count > SCULL_BUFFER_SIZE - dev->size)
{
count = SCULL_BUFFER_SIZE - dev->size;
}
if (raw_copy_from_user(dev->data + dev->size, buf, count))
{
retval = -EFAULT;
goto out;
}
dev->size += count;
retval = count;
out:
up(&dev->sem);
return retval;
}loff_t scull_llseek(struct file *filp, loff_t off, int whence)
{ struct scull_dev *dev = filp->private_data;
loff_t newpos;
switch(whence)
{
case 0:
newpos = off;
break;
case 1:
newpos = filp->f_pos + off;
break;
case 2:
newpos = dev->size + off;
break;
default:
return -EINVAL;
}
if (newpos < 0)
{
return -EINVAL;
}
filp->f_pos = newpos;
return newpos;
}struct file_operations scull_fops = {
.owner = THIS_MODULE,
.llseek = scull_llseek,
.read = scull_read,
.write = scull_write,
.open = scull_open,
.release = scull_release,
};void scull_cleanup_module(void)
{ dev_t devno = MKDEV(scull_major, scull_minor);
if (scull_device)
{
scull_trim(scull_device);
cdev_del(&scull_device->cdev);
kfree(scull_device);
}
unregister_chrdev_region(devno, 1);
}static void scull_setup_cdev(struct scull_dev *dev)
{ int err, devno = MKDEV(scull_major, scull_minor);
cdev_init(&dev->cdev, &scull_fops);
dev->cdev.owner = THIS_MODULE;
dev->cdev.ops = &scull_fops;
err = cdev_add(&dev->cdev, devno, 1);
if (err)
{
printk(KERN_NOTICE "Error %d adding scull", err);
}
}static int __init scull_init_module(void)
{ int result;
dev_t dev = 0;
if (scull_major)
{
dev = MKDEV(scull_major, scull_minor);
result = register_chrdev_region(dev, 1, "scull");
}
else
{
result = alloc_chrdev_region(&dev, scull_minor, 1, "scull");
scull_major = MAJOR(dev);
}
if (result < 0)
{
printk(KERN_WARNING "scull: can't get major %d\n", scull_major);
return result;
}
scull_device = kmalloc(sizeof(struct scull_dev), GFP_KERNEL);
if (!scull_device)
{
result = -ENOMEM;
goto fail;
}
memset(scull_device, 0, sizeof(struct scull_dev));
sema_init(&scull_device->sem, 1);
scull_setup_cdev(scull_device);
return 0;
fail:
scull_cleanup_module();
return result;
}module_init(scull_init_module);module_exit(scull_cleanup_module);MODULE_LICENSE("GPL");
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附2：scull.h
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#ifndef _SCULL_H#define _SCULL_H#define SCULL_MAJOR 0#define SCULL_BUFFER_SIZE PAGE_SIZEstruct scull_dev {
char *data;
unsigned long size;
struct semaphore sem;
struct cdev cdev;
};#endif |
附3：Makefile
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#sample driver moduleobj-m := scull.oKDIR = /root/linux-2.6.36.4/
PWD:=$(shell pwd)
INSTALLDIR=$(PWD)modules: $(MAKE) -C /lib/modules/`uname -r`/build M=`pwd` modules
clean: rm -f *.mod.c *.mod.o *.ko *.o *.tmp_versions
.PHONY:modules clean |
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