can kprobes be modular?

[David Wilder]

Roland McGrath wrote:

>I was reading over some things, and it occurred to me that kprobes ought to
>be a loadable kernel module.  I don't have any special motivation for this.
>It just seems like an unclean situation that it can't be a module now.
>Perhaps many kernels will want to build it in anyway, but I can't see why
>it isn't a module.  It's not very big, but neither are many other things
>that are used much more often and are built as modules.
>
>The #ifdef CONFIG_KPROBES sections in e.g. arch/i386/kernel/traps.c look to
>me like things that ought to be enabled unconditionally, so kprobes or any
>other module could use them.  Things like register_page_fault_notifier
>ought to just be enabled and exported by default.
>
>Thoughts?
>
>
>Thanks,
>Roland
>  
>
What do we gain by making kprobes a module?  The only reason I can think 
of is so a system administrator could disable the feature at will to 
prevent possible security holes.   Any other reasons to do this?.

On the s390 side, kprobes is dependent code in the core exception 
handlers in entry.S.  This can't be put into a module so a new interface 
would need to be created that kprobes could use.   Is it worth adding 
another layer?

-- 
David Wilder
IBM Linux Technology Center
Beaverton, Oregon, USA 
dwilder@us.ibm.com
(503)578-3789