linux内核内存映射实验报告,学习笔记-Linux 内存映射应用

野性酷女 2023-01-20 08:20 212阅读 0赞

/\*

\*    文件名称: zhc\_led.c

\*    摘    要: mmap 学习驱动

\*    当前版本: 1.0

\*    作    者: Love 梦想

\*    完成日期:

\*    取代版本:

\*    原作者  :

\*    完成日期:

\*/

\#define \_\_ISDEBUG\_\_                // 开启打印信息

\#include

\#define DEVICE\_NAME "mymap"

\#define MALLOC\_SIZE        (8192 \* 100)

\#define USE\_KMALLOC        1

static unsigned char array\[10\]= \{0,1,2,3,4,5,6,7,8,9\};

unsigned char     \*g\_mmap\_buff = NULL;

int             g\_mmap\_buff\_size = MALLOC\_SIZE;

// 分配内存

int mmap\_alloc(unsigned char \*\*mmap\_buff, int require\_buf\_size)

struct page     \*page;

unsigned char     \*mmap\_buf\_t;

int             mmap\_size;

int                i;

mmap\_size = PAGE\_ALIGN(require\_buf\_size);

\#if USE\_KMALLOC //for kmalloc

mmap\_buf\_t = kzalloc(mmap\_size, GFP\_KERNEL);

if (!mmap\_buf\_t)

return -1;

for (page = virt\_to\_page(mmap\_buf\_t ); page < virt\_to\_page(mmap\_buf\_t + mmap\_size); page++)

SetPageReserved(page);

\#else //for vmalloc

mmap\_buf\_t  = vmalloc(mmap\_size);

if (!mmap\_buf\_t )

return -1;

for (i = 0; i < mmap\_size; i += PAGE\_SIZE)

SetPageReserved(vmalloc\_to\_page((void \*)(((unsigned long)mmap\_buf\_t) + i)));

\#endif

\*mmap\_buff = mmap\_buf\_t;

return mmap\_size;

void mmap\_free(unsigned char \*mmap\_buf, int mmap\_size)

\#if USE\_KMALLOC

struct page \*page;

for (page = virt\_to\_page(mmap\_buf); page < virt\_to\_page(mmap\_buf + mmap\_size); page++)

ClearPageReserved(page);

kfree(mmap\_buf);

\#else

int i;

for (i = 0; i < mmap\_size; i += PAGE\_SIZE)

ClearPageReserved(vmalloc\_to\_page((void \*)(((unsigned long)mmap\_buf) + i)));

vfree(mmap\_buf);

\#endif

mmap\_buf = NULL;

static int my\_open(struct inode \*inode, struct file \*file)

dprintk();

return 0;

static int my\_map(struct file \*filp, struct vm\_area\_struct \*vma)

int             ret;

unsigned long     pfn;

unsigned long     start = vma->vm\_start;

unsigned long     size = PAGE\_ALIGN(vma->vm\_end - vma->vm\_start);

int                i;

unsigned char     \*mmap\_buff = g\_mmap\_buff;

if (size > g\_mmap\_buff\_size || !g\_mmap\_buff)

return -EINVAL;

dprintk("g\_mmap\_buff = 0x%x", g\_mmap\_buff);

//往该内存写10字节数据

for(i=0; i<10; i++)

mmap\_buff\[i\] = array\[i\];

\#if USE\_KMALLOC

return remap\_pfn\_range(vma, start, (virt\_to\_phys(g\_mmap\_buff) >> PAGE\_SHIFT), size, PAGE\_SHARED);

\#else

/\* loop over all pages, map it page individually \*/

while (size > 0)

pfn = vmalloc\_to\_pfn(mmap\_buff);

if ((ret = remap\_pfn\_range(vma, start, pfn, PAGE\_SIZE, PAGE\_SHARED)) < 0)

return ret;

start += PAGE\_SIZE;

mmap\_buff += PAGE\_SIZE;

size -= PAGE\_SIZE;

\#endif

return 0;

static struct file\_operations dev\_fops =

.owner    = THIS\_MODULE,

.open    = my\_open,

.mmap   = my\_map,

\};

static struct miscdevice misc =

.minor = MISC\_DYNAMIC\_MINOR,

.name = DEVICE\_NAME,

.fops = &dev\_fops,

\};

static ssize\_t hwrng\_attr\_current\_show(struct device \*dev,

struct device\_attribute \*attr,

char \*buf)

int i;

for(i = 0; i < 10 ; i++)

printk("%d\\n",g\_mmap\_buff\[i\]);

return 0;

static DEVICE\_ATTR(rng\_current, S\_IRUGO | S\_IWUSR,

hwrng\_attr\_current\_show,

NULL);

static int \_\_init dev\_init(void)

int ret;

dprintk();

//注册混杂设备

ret = misc\_register(&misc);

//内存分配

ret = mmap\_alloc(&g\_mmap\_buff, g\_mmap\_buff\_size);

dprintk("ret = %d\\n", ret);

if(NULL == g\_mmap\_buff)

eprintk("g\_mmap\_buff => NULL");

return 0;

ret = device\_create\_file(misc.this\_device,&dev\_attr\_rng\_current);

return ret;

static void \_\_exit dev\_exit(void)

dprintk();

//注销设备

misc\_deregister(&misc);

mmap\_free(g\_mmap\_buff, g\_mmap\_buff\_size);

module\_init(dev\_init);

module\_exit(dev\_exit);

MODULE\_LICENSE("GPL");

应用：

\#include

\#define PAGE\_SIZE 4096 \* 2

int main(int argc , char \*argv\[\])

int fd;

int i;

unsigned char \*p\_map;

//打开设备

fd = open("/dev/mymap",O\_RDWR);

if(fd < 0)

printf("open fail\\n");

exit(1);

//内存映射

p\_map = (unsigned char \*)mmap(0, PAGE\_SIZE, PROT\_READ | PROT\_WRITE, MAP\_SHARED,fd, 0);

if(p\_map == MAP\_FAILED)

printf("mmap fail\\n");

goto here;

//打印映射后的内存中的前10个字节内容

for(i=0; i<10; i++)

printf("%d\\n",p\_map\[i\]);

p\_map\[i\] = i + 1;

strcpy(p\_map, "adcdefghij");

here:

munmap(p\_map, PAGE\_SIZE);

return 0;

linux内核内存映射实验报告,学习笔记-Linux 内存映射应用

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