HI ALL,
I need to invalidate a user process page . To
invalidate the page , i need to get into kernel space
, so i am using
the ioctl func of a char device driver. I am not
getting the right functions or the right way to
invalidate a page.
This is my code .
User level process
#include <stdio.h>
#include <fcntl.h>
#define MAX 3000
int main()
{
int fd,ch,val,i;
int *buff;
fd=open("filepte", O_RDWR);
if (!fd)
{
perror("OPEN");
exit(1);
}
printf("\nThe pid of the process is %d",getpid());
buff=(void *)malloc(sizeof(int)*MAX);
// Declaring the buffer
printf("\n The address of buff[0]is
%x,\n",&buff[0]);
for (i=0;i<MAX;i++)
buff[i]=20;
// Accessing the buffer (pages)
ioctl(fd,1,&buff[0]);
// Calling ioctl of the device
driver
for(i=0;i<MAX;i++)
buff[i]=i+1;
// Accessing the buffer again
(pages)
printf("The first element of the buffer is
%d",buff[0]);
close(fd);
return(0);
}
Kernel code
(Device driver)
IOCTL FUNCTION
static int motspk_ioctl(struct inode *inode, struct
file *file,unsigned int cmd, unsigned long arg)
{
/* The virtual address comes in the
parameter "arg" . I want to invalidate the page
corresponding
to the virtual address */
struct vm_area_struct *vma1=NULL;
pte_t *page_table,pg_pte,res;
struct page *pgptr=NULL;
struct mm_struct* mm;
mm=current->mm;
printk(KERN_ALERT "The pid of the driver is
%d",current->pid);
printk(KERN_ALERT "Entered IOCTL and the addr is
%x\n",arg);
vma1=find_vma(current->mm,arg);
// Find the vma
pg_pte=pfn_pte(page_to_pfn(pgptr),PAGE_SHARED);
// Getting the pte for the
page
pte_clear(current->mm,arg,&pg_pte);
// Clearing pte
flush_tlb_page(vma1,arg);
// Flushing tlb page
return 0;
}
Thank u in advance.
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