linux内核驱动模块写文件

﹏ヽ暗。殇╰゛Y 2022-06-18 03:38 384阅读 0赞

最近项目中遇到一个问题，需要在驱动ko文件中写文件记录log，网上google了半天，要么不能用，要么直接编译不通过，最后参考内核源码linux-2.6.38/drivers/staging/spectra/lld\_emu.c才搞定，主要如下：  
  
1.我内核版本为2.6.38，编译器gcc version 4.4.1 (Sourcery G++ Lite 2009q3-67)；  
2.使用网上说的sys\_open编译没问题，加载时会提示unknown symbol错误，估计是没有EXPORT\_SYMBOL，所以不能在ko文件中使用；  
3.使用网上一个filp\_open例子，里面还调用了ioctl相关，直接编译错误，去除相关错误后，又加载错误；  
4.用cscope搜索调用filp\_open相关地方，找到drivers/staging/spectra/lld\_emu.c里面有一个int emu\_write\_mem\_to\_file(void)，copy出来，几乎不用修改直接可以使用，源码如下：

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1.  \#include <linux/kernel.h>  
    
2.  \#include <linux/init.h>  
    
3.  \#include <linux/module.h>  
    
4.  \#include <linux/syscalls.h>  
    
5.  \#include <linux/file.h>  
    
6.  \#include <linux/fs.h>  
    
7.  \#include <linux/fcntl.h>  
    
8.  \#include <asm/uaccess.h>  
    
9.  \#include <linux/stat.h>  
    
10. \#include <asm/unistd.h>  
    
11. \#include <linux/types.h>  
    
12.   
    
13. static int write\_log\_file(char \*filename, char \*data\_w) \{   
    
14.     mm\_segment\_t fs;  
    
15.     struct file \*nef\_filp = NULL;  
    
16.     struct inode \*inode = NULL;  
    
17.     loff\_t nef\_size = 0;  
    
18.     loff\_t tmp\_file\_offset;  
    
19.     ssize\_t nwritten;  
    
20.     int rc = \-EINVAL;  
    
21.     int str\_len;  
    
22.   
    
23.     fs = get\_fs();  
    
24.     set\_fs(get\_ds());  
    
25.   
    
26.     nef\_filp = filp\_open(filename, O\_CREAT | O\_RDWR, 0);  
    
27.     if (IS\_ERR(nef\_filp)) \{   
    
28.         printk(KERN\_ERR "filp\_open error: "  
    
29.                "Unable to open nand emu file!\\n");  
    
30.         return PTR\_ERR(nef\_filp);  
    
31.     \}  
    
32.   
    
33.     if (nef\_filp\->f\_path.dentry) \{   
    
34.         inode = nef\_filp\->f\_path.dentry\->d\_inode;  
    
35.     \} else \{   
    
36.         printk(KERN\_ERR "Invalid " "nef\_filp->f\_path.dentry value!\\n");  
    
37.         goto out;  
    
38.     \}  
    
39.   
    
40.     nef\_size = i\_size\_read(inode\->i\_mapping\->host);  
    
41.     if (nef\_size < 0) \{   
    
42.         printk(KERN\_ERR "Invalid "  
    
43.                "nand emu file size: 0x%llx\\n", nef\_size);  
    
44.         goto out;  
    
45.     \} else \{   
    
46.         printk(KERN\_ERR "nand emu file size: ""%lld\\n", nef\_size);  
    
47.     \}  
    
48.   
    
49.     str\_len = strlen(data\_w) \+ 1;  
    
50.     tmp\_file\_offset = nef\_size;  
    
51.     nwritten = vfs\_write(nef\_filp,  
    
52.                  (char \_\_user \*)data\_w,  
    
53.                  str\_len, &tmp\_file\_offset);  
    
54.     if (nwritten < str\_len) \{   
    
55.         printk(KERN\_ERR "%s, Line %d - "  
    
56.                "nand emu file partial write: "  
    
57.                "%d bytes\\n", \_\_FILE\_\_, \_\_LINE\_\_, (int)nwritten);  
    
58.         goto out;  
    
59.     \}  
    
60.       
    
61.     rc = 0;  
    
62.   
    
63. out:  
    
64.     filp\_close(nef\_filp, current\->files);  
    
65.     set\_fs(fs);  
    
66.     return rc;  
    
67. \}

在合适处调用如write\_log\_file("/root/kernel\_reboot.txt", "rebooting...\\n\\n")即可。

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