lkml.org 
[lkml]   [2012]   [Apr]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 6/7] mm: kill vma flag VM_EXECUTABLE
On Thu, Apr 05, 2012 at 01:29:04PM -0700, Matt Helsley wrote:
...
> > > Doesn't that break the semantics of the kernel ABI?
> >
> > Which one? exe_file can be changed iif there is no MAP_EXECUTABLE left.
> > Still, once assigned (via this prctl) the mm_struct::exe_file can't be changed
> > again, until program exit.
>
> The prctl() interface itself is fine as it stands now.
>
> As far as I can tell Konstantin is proposing that we remove the unusual
> counter that tracks the number of mappings of the exe_file and require
> userspace use the prctl() to drop the last reference. That's what I think
> will break the ABI because after that change you *must* change userspace
> code to use the prctl(). It's an ABI change because the same sequence of
> system calls with the same input bits produces different behavior.

Hi Matt, I see what you mean (I misread your email at first, sorry).
Sure it's impossible to patch already existing programs (and btw, this
prctl code actually won't help a program to drop symlink completely
and live without it then, because old one will gone but new one
will be assigned) so personally I can't answer here on Konstantin's
behalf, but I guess the main question is -- which programs use this
'drop-all-MAP_EXECUTABLE' feature?

Cyrill


\
 
 \ /
  Last update: 2012-04-05 22:55    [W:0.069 / U:0.172 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site