On 4/16/07, Thomas Christensen <thomasc@xxxxxxxxxxx> wrote:
Greetings,
On Mon, Apr 16, 2007 at 01:48:24AM +0700, Mulyadi Santosa wrote:
> > 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)?
>
> AFAIK, check find_vma(), defined in include/linux/mm.h
I can see that I have not been as clear as I could have been.
Firstly I think it's called logical address, not virtual address, when
allocated with __get_free_pages(), so I will start using that term
instead.
The problem is not finding the struct vm_area_struct * -- I can have
that conveniently stored in private data.
The problem is that I have allocated N non-consecutive pages, and added
them to a mmap ranging from A to B of size N * PAGE_SIZE.
My problem is that I have a logical address contained by one of the
pages, and I need to find the corresponding userland address (ranging
from A and B).
Let's say the user read address USERADDR, which the memory map
translates to LOGICADDR. What I want is the reverse translation, in
kernel space, so I can printk it or copy it to userspace on ioctl or
something similar.
I hope this is clearer, if not feel free to ask, and I will elaborate
the best I can.
Sincerely,
Thomas
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I hope you would want to look at remap_pfn_range ?
