Re: [PATCH] x86/vdso: Add prctl to set per-process VDSO load

[Filipe Brandenburger]

Hi Andy,

On Fri, Sep 19, 2014 at 12:27 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> I have this (special mapping tracking) 3/4 implemented.  I'm planning
> on making it fully functional for 64-bit programs and almost correct
> for 32-bit.  (You'll still crash if you have multiple threads, you use
> sysenter, and you remap the vdso, but I think that this is essentially
> unavoidable until someone lets mremap work on multiple vmas at once.)

In case that's useful, I was looking at swapping the vvar page by
changing the vm_special_mapping to change the pages array between the
actual vvar page and the zero page and using zap_page_range to force
the next access to go through a page fault that would remap it.

I didn't have all the details figured out (I was closer to 1/4 of it
implemented) but I didn't see any issues on 32-bit programs.

Let me know if you'd like to see some of my patches or if you think I
should keep working on them.

Cheers,
Filipe
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