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Subject: Re: [PATCH v3 2.6.39-rc1-tip 12/26] 12: uprobes: slot allocation
 for uprobes
From: Peter Zijlstra <peterz@infradead.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: James Morris <jmorris@namei.org>, Ingo Molnar <mingo@elte.hu>,
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Date: Tue, 19 Apr 2011 11:02:26 +0200
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On Tue, 2011-04-19 at 11:56 +0530, Srikar Dronamraju wrote:
> > > +   /*
> > > +    * Find the end of the top mapping and skip a page.
> > > +    * If there is no space for PAGE_SIZE above
> > > +    * that, mmap will ignore our address hint.
> > > +    *
> > > +    * We allocate a "fake" unlinked shmem file because
> > > +    * anonymous memory might not be granted execute
> > > +    * permission when the selinux security hooks have
> > > +    * their way.
> > > +    */
> > 
> > That just annoys me, so we're working around some stupid sekurity crap,
> > executable anonymous maps are perfectly fine, also what do JITs do?
> 
> Yes, we are working around selinux security hooks, but do we have a
> choice. 

Of course you have a choice, mark selinux broken and let them sort
it ;-)

Anyway, it looks like install_special_mapping() the thing I think you
ought to use (and I'm sure I said that before) also wobbles around
selinux by using security_file_mmap() even though its very clearly not a
file mmap (hint: vm_file == NULL).