Re: [RFC 1/3] x86/vdso: create vdso file, use it for mapping

Andy Lutomirski
2016-08-30T14:58:32Z

On Mon, Aug 29, 2016 at 2:50 AM, Dmitry Safonov <dsafonov@virtuozzo.com> wrote:
> On 08/29/2016 12:28 PM, Andy Lutomirski wrote:
>>
>> On Thu, Aug 25, 2016 at 8:21 AM, Dmitry Safonov <dsafonov@virtuozzo.com>
>> wrote:
>>>
>>> I added here a new in-kernel fs with ramfs-like options.
>>> Created vdso file in this fs (yet for testing, only 64-bit vdso).
>>> Mapped this file to process's mm on setup_additional_pages.
>>> Just for testing purpose it's done only for specific UID.
>>
>>
>> I'm wondering whether all this code could be easily moved into the
>> core special mapping helpers so that all special mappings get the same
>> benefit. We could embed a struct file * (or struct inode or whatever)
>> in special_mapping if needed.
>
>
> Hmm, yes, I guess. The only thing -- we'll still need per-arch changes
> to initialize those files on booting. But that looks like the proper
> generic place to move this code.

You might be able to get away with initializing on first use.

--Andy