On Sun, 2007-04-15 at 14:29 +0200, Thomas Christensen wrote:
> Hi kernelnewbies,
>
> I have allocated some pages with multiple calls to __get_free_pages(),
> and added them to a vm area with calls to vm_insert_page().
>
> The question is: given an arbitrary kernel address contained by one of
> the pages, does Linux expose an API to translate that address to the
> userland address (vm area address)?
>
I Dont know if there is a direct api for this....
but you can get it using the following logic (very long search :)).
get the page frame no by --> kernel address >> PAGE_SHIFT
get the struct page using -> mem_map + page frame no
struct page->mapping->i_mmap will give you a linked list of
vm_area_struct
now for each vma
->mm->pdg will give you the pgd base
now for each pte entry in the page table
if (pte >> page_shift == kernel_address >> page_shift) {
get virtual address for that particular pgd and pte entry(address
translation logic).
}
can someone please verify this ?
OR
a simpler solution would be to maintain the list of user address of that
page when you call vm_insert_page :).
ps: there are macros for some of the above steps.
--
Vivek Kutal
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