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Date: Mon, 25 Jun 2007 19:00:57 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Michael Ellerman <michael@ellerman.id.au>
Subject: Re: [PATCH 3/3] Make jprobes a little safer for users
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On Tue, 26 Jun 2007 11:48:51 +1000 (EST) Michael Ellerman <michael@ellerman.id.au> 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.
> 
> Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
> ---
>  arch/ia64/kernel/kprobes.c    |    7 ++++++-
>  arch/powerpc/kernel/kprobes.c |   11 ++++++++---
>  kernel/kprobes.c              |    9 +++++++++

We're missing a declaration of arch_deref_entry_point() in some header file?