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Re: can kprobes be modular?

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.



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

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