[CRIU] [PATCH 5/5] parse_smaps: Don't mark vdso if prot mismatch

[Cyrill Gorcunov]

On Mon, May 20, 2013 at 03:57:58PM +0400, Pavel Emelyanov wrote:
> On 05/16/2013 07:33 PM, Cyrill Gorcunov wrote:
> > 
> > [vdso] mark is not very consistent in proc output.
> > Thus if vma has no VDSO_PROT set we can safetly assume
> > it's not vdso area.
> > 
> > Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
> > ---
> >  proc_parse.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> 
> in this case we can be in situation when no vmas are marked as
> vdso and we fail to proxify it on the 2nd dump/restore.

vdso is executable code, if application has remapped own vdso
as non-executable one -- it's up to this application to fail
in attempt to execute code without 'x' prot.

Look, letme explain. The [vdso] mark in procfs is inconsistent,
I can't trust it. Thus I need to parse vma content and figure
out if it's vdso area or not.

Still I don't want to walk over all VMAs the task has, since it's
time consuming.

Thus I assume, since vdso area is executable, it must have at least
'rx' prot. So I can skip calling for vdso parser for all vmas which
do not fit this requirement, this speeds up procedure significantly
that I don't even need to call for parasite helpers.