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 |
1 下载内核源码，构建源码树
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sudo apt install linux-source-4.15.0 -ycd /usr/src/linux-source-4.15.0/sudo tar xf linux-source-4.15.0.tar.bz2cd linux-source-4.15.0/sudo make oldconfigsudo make preparesudo make scripts |
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.kosudo rmmod scull.ko |
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
", 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"); |
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` modulesclean: rm -f *.mod.c *.mod.o *.ko *.o *.tmp_versions.PHONY:modules clean |