CODEWITHSUNDEEP
cmemorylinux-kerneloperating-system
Blackdragon1400
Blackdragon1400

Reputation: 423

Find page in memory for Process (linux-kernel)

Basically I have a program that can find all the VMA's of a process, but I would like to look at the pages in the page table for that process as well. I'm stumped. I know that the task_struct for the process has a field 

pgd_t                  *pgd;                /* page global directory */

Is that just an array of indexes to ALL of the pages?

I found this function inside of "/mm/memory.c"

/*
* Do a quick page-table lookup for a single page.
*/
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
                    unsigned int flags)

I can pass it a VMA, but I am unsure about what the address and flags should be. Or perhaps this isn't what I want? Any advice?

Upvotes: 0

Views: 2426

Answers (1)

Michael
Michael

Reputation: 2261

It sounds like you want to do a rudimentary page walk.

Given a pgd, you can iterate through the entries looking for valid pud's, then iterate through the pud's and so on.

One way to do this is using the following:

// iterate through your address space
for (i = 0; i < PAGE_SIZE / sizeof(*pud); i++) {
    pud = pud_offset(pgd, PUD_SIZE * i);
    // Check if the pud is valid
    if (pud_none(*pud) || pud_bad(*pud))
        continue;
    // And so on
}

Upvotes: 2

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