[CRIU] [PATCH 3/3] arm64: detect vDSO remaps

[Alexander Kartashov]

On 03/11/2014 02:51 PM, Cyrill Gorcunov wrote:
> Alexander, there is aspect I don't understand (you might be explaining
> me but I start to doubt again). Here is what we have on x86-64
>
>   - once proceess starts up the kernel provides vDSO area for it
>   - if such vdso area intersects with image addresses we
>    - remap runtime vdso to a new free address with MAP_FIXED
>    - map old vDSO from image to original address then proxify it if needed
>
> how it's different from ARM64?
It's exactly the same but for tiny nuance: the kernel initializes
some variables in the arm64 specific part of a task_struct
when a process is created binding them to vDSO symbols:
particularly the signal trampoline is situated in the vDSO
and the kernel stores its address in the task struct.
This means it's impossible to remap the vDSO area without
breaking signal handling.

This patch copes with this problem by adjusting the task struct
when the vDSO area is remapped.

-- 
Sincerely yours,
Alexander Kartashov

Intern
Core team

www.parallels.com

Skype: aleksandr.kartashov
Email: alekskartashov at parallels.com