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Date: Tue, 26 Jun 2007 07:53:47 +0200
From: Christoph Hellwig <hch@lst.de>
To: Michael Ellerman <michael@ellerman.id.au>
Subject: Re: [PATCH 3/3] Make jprobes a little safer for users
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Cc: linux-arch@vger.kernel.org, Andrew Morton <akpm@osdl.org>,
	linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org,
	anil.s.keshavamurthy@intel.com, linuxppc-dev@ozlabs.org,
	Christoph Hellwig <hch@lst.de>
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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.