Linux内核模块驱动加载与dmesg调试

玖柒的小窝

修改于 2021-09-15 11:39:31

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修改于 2021-09-15 11:39:31

文章被收录于专栏：各类技术文章~各类技术文章~

因为近期用到了Linux内核的相关知识，下面随笔将给出内核模块的编写记录，供大家参考。

1、运行环境

　　Ubuntu 版本：20.04

　　Linux内核版本：5.4.0-42-generic

　　gcc版本：gcc version 9.3.0

　　驱动和一般应用程序的执行方式很大不同

2、内核模块模型说明

（1）驱动和一般应用程序的执行方式很大不同

　　一般应用由main函数开始执行，流程基本由程序自身控制

　　驱动程序没有main函数，由回调方式驱动运行

（2）回调方式：

　　先向内核注册函数，然后应用程序触发这些函数的执行

　　例如：驱动程序在初始化时，向内核注册处理某个设备写操作的函数

　　当应用程序使用write系统调用写该设备时，内核就会调用注册的上述函数

3、内核模型常见的回调函数举例

（1）DriverInitialize

　　驱动初始化函数，通过宏静态注册；

　　$ insmod PrintModule.ko，安装驱动并触发该函数，通常会创建设备对象；

（2）DriverUninitialize

　　驱动销毁函数，通过宏静态注册；

　　$ rmmod PrintModule，卸载驱动并触发该函数；

（3）DriverOpen

　　打开设备函数，动态注册；

　　应用调用open函数打开设备对象时，会触发该函数；

（4）DriverRead

　　读设备函数，动态注册；

　　应用调用read函数读设备时，会触发该函数；

（5）DriverWrite

　　写设备函数，动态注册；

　　应用调用write函数写设备时，会触发该函数；

（7）DriverIOControl

　　设备控制函数，动态注册；

　　应用调用ioctl函数操作设备时，会触发该函数；

（8）DriverMMap

　　设备内存映射函数，动态注册；

　　应用调用mmap函数时，会触发该函数；

下面给出驱动模块编写函数：

4、DriverMain.c

C++

  1 #include "DriverMain.h"
  2 
  3 #include "DriverFileOperations.h"
  4 
  5 #include "ToolFunctions.h"
  6 
  7 
  8 
  9 MODULE_LICENSE("Dual BSD/GPL");
 10 
 11 
 12 
 13 struct SLDriverParameters gslDriverParameters = {0};
 14 
 15 
 16 
 17 struct file_operations gslNvmDriverFileOperations = 
 18 
 19 {
 20 
 21     .owner = THIS_MODULE,
 22 
 23     .open  = DriverOpen,
 24 
 25     .release = DriverClose,
 26 
 27     .read  = DriverRead,
 28 
 29     .write = DriverWrite,
 30 
 31     .unlocked_ioctl = DriverIOControl,
 32 
 33     .mmap = DriverMMap,
 34 
 35 };
 36 
 37 
 38 
 39 int InitalizeCharDevice(void)
 40 
 41 {
 42 
 43     int result;
 44 
 45     struct device *pdevice;
 46 
 47 
 48 
 49     result = alloc_chrdev_region(&(gslDriverParameters.uiDeviceNumber), 0, 1, DEVICE_NAME);
 50 
 51     if(result < 0)
 52 
 53     {
 54 
 55         printk(KERN_ALERT DEVICE_NAME " alloc_chrdev_region error\n");
 56 
 57         return result;
 58 
 59     }
 60 
 61 
 62 
 63     gslDriverParameters.pslDriverClass = class_create(THIS_MODULE, DEVICE_NAME);
 64 
 65     if(IS_ERR(gslDriverParameters.pslDriverClass)) 
 66 
 67     {
 68 
 69         printk(KERN_ALERT DEVICE_NAME " class_create error\n");
 70 
 71 
 72 
 73         result = PTR_ERR(gslDriverParameters.pslDriverClass);
 74 
 75         goto CLASS_CREATE_ERROR;
 76 
 77     }
 78 
 79 
 80 
 81     cdev_init(&(gslDriverParameters.slCharDevice), &gslNvmDriverFileOperations);
 82 
 83     gslDriverParameters.slCharDevice.owner = THIS_MODULE;
 84 
 85 
 86 
 87     result = cdev_add(&(gslDriverParameters.slCharDevice), gslDriverParameters.uiDeviceNumber, 1);
 88 
 89     if(result < 0) 
 90 
 91     {
 92 
 93         printk(KERN_ALERT DEVICE_NAME " cdev_add error\n");
 94 
 95         goto CDEV_ADD_ERROR;
 96 
 97     }
 98 
 99 
100 
101     pdevice = device_create(gslDriverParameters.pslDriverClass, NULL, gslDriverParameters.uiDeviceNumber, NULL, DEVICE_NAME);
102 
103     if(IS_ERR(pdevice)) 
104 
105     {
106 
107         printk(KERN_ALERT DEVICE_NAME " device_create error\n");
108 
109 
110 
111         result = PTR_ERR(pdevice);
112 
113         goto DEVICE_CREATE_ERROR;
114 
115     }
116 
117 
118 
119     return 0;
120 
121 
122 
123 DEVICE_CREATE_ERROR:
124 
125     cdev_del(&(gslDriverParameters.slCharDevice));
126 
127 
128 
129 CDEV_ADD_ERROR:
130 
131     class_destroy(gslDriverParameters.pslDriverClass);
132 
133 
134 
135 CLASS_CREATE_ERROR:
136 
137     unregister_chrdev_region(gslDriverParameters.uiDeviceNumber, 1);
138 
139 
140 
141     return result;
142 
143 }
144 
145 
146 
147 void UninitialCharDevice(void)
148 
149 {
150 
151     device_destroy(gslDriverParameters.pslDriverClass, gslDriverParameters.uiDeviceNumber);
152 
153 
154 
155     cdev_del(&(gslDriverParameters.slCharDevice));
156 
157 
158 
159     class_destroy(gslDriverParameters.pslDriverClass);
160 
161 
162 
163     unregister_chrdev_region(gslDriverParameters.uiDeviceNumber, 1);
164 
165 }
166 
167 
168 
169 static int DriverInitialize(void)
170 
171 {
172 
173     DEBUG_PRINT(DEVICE_NAME " Initialize\n");
174 
175 
176 
177     return InitalizeCharDevice();
178 
179 }
180 
181 
182 
183 static void DriverUninitialize(void)
184 
185 {
186 
187     DEBUG_PRINT(DEVICE_NAME " Uninitialize\n");
188 
189 
190 
191     UninitialCharDevice();
192 
193 }
194 
195 
196 
197 module_init(DriverInitialize);
198 
199 module_exit(DriverUninitialize);

5、DriverMain.h

C++

 1 #ifndef DriverMain_H
 2 
 3 #define DriverMain_H
 4 
 5 
 6 
 7 #include <linux/init.h>
 8 
 9 #include <linux/module.h>
10 
11 #include <asm/mtrr.h>
12 
13 #include <linux/device.h>
14 
15 #include <linux/mm.h>
16 
17 #include <linux/cdev.h>
18 
19 #include <linux/slab.h>
20 
21 
22 
23 #define DEVICE_NAME "msg_printer"
24 
25 
26 
27 struct SLDriverParameters
28 
29 {
30 
31     struct class *pslDriverClass;
32 
33     dev_t uiDeviceNumber;
34 
35     struct cdev slCharDevice;
36 
37 };
38 
39 
40 
41 extern struct SLDriverParameters gslDriverParameters;
42 
43 
44 
45 #endif

6、DriverFileOperations.c

C++

  1 #include "DriverMain.h"
  2 
  3 #include "DriverFileOperations.h"
  4 
  5 #include "ToolFunctions.h"
  6 
  7 
  8 
  9 MODULE_LICENSE("Dual BSD/GPL");
 10 
 11 
 12 
 13 struct SLDriverParameters gslDriverParameters = {0};
 14 
 15 
 16 
 17 struct file_operations gslNvmDriverFileOperations = 
 18 
 19 {
 20 
 21     .owner = THIS_MODULE,
 22 
 23     .open  = DriverOpen,
 24 
 25     .release = DriverClose,
 26 
 27     .read  = DriverRead,
 28 
 29     .write = DriverWrite,
 30 
 31     .unlocked_ioctl = DriverIOControl,
 32 
 33     .mmap = DriverMMap,
 34 
 35 };
 36 
 37 
 38 
 39 int InitalizeCharDevice(void)
 40 
 41 {
 42 
 43     int result;
 44 
 45     struct device *pdevice;
 46 
 47 
 48 
 49     result = alloc_chrdev_region(&(gslDriverParameters.uiDeviceNumber), 0, 1, DEVICE_NAME);
 50 
 51     if(result < 0)
 52 
 53     {
 54 
 55         printk(KERN_ALERT DEVICE_NAME " alloc_chrdev_region error\n");
 56 
 57         return result;
 58 
 59     }
 60 
 61 
 62 
 63     gslDriverParameters.pslDriverClass = class_create(THIS_MODULE, DEVICE_NAME);
 64 
 65     if(IS_ERR(gslDriverParameters.pslDriverClass)) 
 66 
 67     {
 68 
 69         printk(KERN_ALERT DEVICE_NAME " class_create error\n");
 70 
 71 
 72 
 73         result = PTR_ERR(gslDriverParameters.pslDriverClass);
 74 
 75         goto CLASS_CREATE_ERROR;
 76 
 77     }
 78 
 79 
 80 
 81     cdev_init(&(gslDriverParameters.slCharDevice), &gslNvmDriverFileOperations);
 82 
 83     gslDriverParameters.slCharDevice.owner = THIS_MODULE;
 84 
 85 
 86 
 87     result = cdev_add(&(gslDriverParameters.slCharDevice), gslDriverParameters.uiDeviceNumber, 1);
 88 
 89     if(result < 0) 
 90 
 91     {
 92 
 93         printk(KERN_ALERT DEVICE_NAME " cdev_add error\n");
 94 
 95         goto CDEV_ADD_ERROR;
 96 
 97     }
 98 
 99 
100 
101     pdevice = device_create(gslDriverParameters.pslDriverClass, NULL, gslDriverParameters.uiDeviceNumber, NULL, DEVICE_NAME);
102 
103     if(IS_ERR(pdevice)) 
104 
105     {
106 
107         printk(KERN_ALERT DEVICE_NAME " device_create error\n");
108 
109 
110 
111         result = PTR_ERR(pdevice);
112 
113         goto DEVICE_CREATE_ERROR;
114 
115     }
116 
117 
118 
119     return 0;
120 
121 
122 
123 DEVICE_CREATE_ERROR:
124 
125     cdev_del(&(gslDriverParameters.slCharDevice));
126 
127 
128 
129 CDEV_ADD_ERROR:
130 
131     class_destroy(gslDriverParameters.pslDriverClass);
132 
133 
134 
135 CLASS_CREATE_ERROR:
136 
137     unregister_chrdev_region(gslDriverParameters.uiDeviceNumber, 1);
138 
139 
140 
141     return result;
142 
143 }
144 
145 
146 
147 void UninitialCharDevice(void)
148 
149 {
150 
151     device_destroy(gslDriverParameters.pslDriverClass, gslDriverParameters.uiDeviceNumber);
152 
153 
154 
155     cdev_del(&(gslDriverParameters.slCharDevice));
156 
157 
158 
159     class_destroy(gslDriverParameters.pslDriverClass);
160 
161 
162 
163     unregister_chrdev_region(gslDriverParameters.uiDeviceNumber, 1);
164 
165 }
166 
167 
168 
169 static int DriverInitialize(void)
170 
171 {
172 
173     DEBUG_PRINT(DEVICE_NAME " Initialize\n");
174 
175 
176 
177     return InitalizeCharDevice();
178 
179 }
180 
181 
182 
183 static void DriverUninitialize(void)
184 
185 {
186 
187     DEBUG_PRINT(DEVICE_NAME " Uninitialize\n");
188 
189 
190 
191     UninitialCharDevice();
192 
193 }
194 
195 
196 
197 module_init(DriverInitialize);
198 
199 module_exit(DriverUninitialize);

7、DriverFileOperations.h

C++

 1 #ifndef DriverFileOperations_H
 2 
 3 #define DriverFileOperations_H
 4 
 5 int DriverOpen(struct inode *pslINode, struct file *pslFileStruct)
 6 
 7 int DriverClose(struct inode *pslINode, struct file *pslFileStruct);
 8 
 9 ssize_t DriverRead(struct file *pslFileStruct, char __user *pBuffer, size_t nCount, loff_t *pOffset);
10 
11 ssize_t DriverWrite(struct file *pslFileStruct, const char __user *pBuffer, size_t nCount, loff_t *pOffset);
12 
13 long DriverIOControl(struct file *pslFileStruct, unsigned int uiCmd, unsigned long ulArg);
14 
15 int DriverMMap(struct file *pslFileStruct, struct vm_area_struct *pslVirtualMemoryArea);
16 
17 #endif

8、编译内核模块的MakeFile文件：

Makefile

 1 ifneq ($(KERNELRELEASE),)
 2 
 3     obj-m := PrintModule.o
 4 
 5     PrintModule-objs := DriverMain.o DriverFileOperations.o
 6 
 7 EXTRA_CFLAGS := -DTEST_DEBUG -ggdb -O0
 8 
 9 else
10 
11     KERNELDIR ?= /lib/modules/$(shell uname -r)/build
12 
13     PWD := $(shell pwd)
14 
15 default:
16 
17     $(MAKE) -C $(KERNELDIR) M=$(PWD) modules
18 
19     rm *.order *.symvers *.mod.c *.o .*.o.cmd .*.cmd .tmp_versions -rf
20 
21 endif