Re: [PATCH] module interface improvement for kprobes

From: David Smith
Date: Tue Aug 08 2006 - 11:40:30 EST

On Mon, 2006-08-07 at 10:22 +0530, Ananth N Mavinakayanahalli wrote:
> On Fri, Aug 04, 2006 at 04:57:11PM +0100, Christoph Hellwig wrote:

... stuff deleted ...

> > That beeing said we should probably change the kprobes interface to
> > automatically do the kallsysms name lookup for the caller. It would simplify
> > the kprobes interface and allow us to get rid of the kallsyms_lookup_name
> > export that doesn't have a valid use except for kprobes. With
> > that change the example kprobe would look like:
> This sounds like a good idea. How about we still allow .addr atleast for
> users who know what they are doing and would want to just specify a text
> addr?
> > static struct kprobe kp = {
> .addr = <addr>
> > .pre_handler = handler_pre,
> > .post_handler = handler_post,
> > .fault_handler = handler_fault,
> > .symbol_name = "do_fork",
> > };
> The symbol_name lookup can then be done when only when .addr is non-NULL.
> That said, I have a working patch I was planning to post today that
> introduces the KPROBE_ADDR macro that abstracts out the architecture-specific
> artefacts of getting the actual text address to probe, so kprobe modules
> can be made more portable. I was envisaging this to be used by the module
> writer, but with your idea, this could live in-kernel itself.
> I'll cook up a patch for this in a short while.
> Ananth

This does seem reasonable, so I'll abandon my patch and wait for the new
kprobes interface.

Ananth, thanks for helping out.

David Smith
Red Hat, Inc.
256.217.0141 (direct)
256.837.0057 (fax)

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