Re: [PATCHv2 3/6] x86/arch_prctl/vdso: add ARCH_MAP_VDSO_*

[Dmitry Safonov]

On 07/12/2016 05:14 PM, Oleg Nesterov wrote:
> On 07/11, Andy Lutomirski wrote:
> > I'm starting to wonder if we should finally suck it up and give
> > special mappings a non-NULL vm_file so we can track them properly.
> > Oleg, weren't you thinking of doing that for some other reason?
>
> Yes, uprobes. Currently we can't probe vdso page(s).

So, to make sure, that I've understood correctly, I need to:
o add vm_file to vdso/vvar vmas, __install_special_mapping will init
  them;
o place array pages[] inside f_mapping;
o create f_inode for each file -- for this we need some mount point, so
  I'll create something like vdsofs, register this filesystem and mount
  it in initcall (or like do_basic_setup - as it's done by shmem, i.e).

Is this the idea, or I got it wrong?

And maybe the idea is to create fake vm_file for just reference
counting, but do not treat/init it like file with inode, etc?
So with fake file I can also check if vdso is mapped already, but
I'm sure the fake file will not help Oleg with uprobes.

--
             Dmitry