Re: [PATCH 3/3] Make jprobes a little safer for users

On Tue, Jun 26, 2007 at 11:48:51AM +1000, Michael Ellerman wrote:

I realise jprobes are a razor-blades-included type of interface, but
that doesn't mean we can't try and make them safer to use. This guy I
know once wrote code like this:

struct jprobe jp = { .kp.symbol_name = "foo", .entry = "jprobe_foo" };

And then his kernel exploded. Oops.

This patch adds an arch hook, arch_deref_entry_point() (I don't like it either)
which takes the void * in a struct jprobe, and gives back the text address
that it represents.

We can then use that in register_jprobe() to check that the entry point
we're passed is actually in the kernel text, rather than just some random
value.

Please don't add more weak functions, they're utterly horrible for
anyone trying to understand the code.  Otherwise this looks fine to me.