is it by anyway possible to find out the struct page* corresponding to the address of the user space buffer.
if thats possible i'm thinking of using kmap() to map that page to the kernel space. then i should be able to manipulate the buffer from kernel space. is it right..?
i found a function in mm/memory.c struct page * vmalloc_to_page(void * vmalloc_addr) thats able to return the struct page* corresponding to a virtual address. but i think this function is valid only for kernel address..?
TIA,
john
On Tue, 10 Jun 2003 Angelo Dell'Aera wrote :
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On 9 Jun 2003 13:52:39 -0000 "Biswaranjan " <biswaranjan_p@rediffmail.com> wrote:
>Hi,
>
>i'm trying to write a device driver for a particular device. i need
>to manipulate the buffer provided to the kernel during write()
>directly from the kernel without using copy_from_user() due to
>efficiency reasons..
If you are searching for efficiency maybe the best thing you can do is
to call access_ok() on the user space buffer just the first time you
use it and then use __copy_form_user() which is faster than
copy_from_user() since it doesn't perform this kind of test. This is
surely the best you can do AFAIK.
Regards.
- --
Angelo Dell'Aera 'buffer' Antifork Research, Inc. http://buffer.antifork.org
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