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Re: [PATCH] Linux Kernel Markers 0.5 for Linux 2.6.17 (with probe management)
- From: Karim Yaghmour <karim at opersys dot com>
- To: Mathieu Desnoyers <compudj at krystal dot dyndns dot org>
- Cc: Ingo Molnar <mingo at elte dot hu>, Martin Bligh <mbligh at google dot com>, "Frank Ch. Eigler" <fche at redhat dot com>, Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, prasanna at in dot ibm dot com, Andrew Morton <akpm at osdl dot org>, Paul Mundt <lethal at linux-sh dot org>, linux-kernel <linux-kernel at vger dot kernel dot org>, Jes Sorensen <jes at sgi dot com>, Tom Zanussi <zanussi at us dot ibm dot com>, Richard J Moore <richardj_moore at uk dot ibm dot com>, Michel Dagenais <michel dot dagenais at polymtl dot ca>, Christoph Hellwig <hch at infradead dot org>, Greg Kroah-Hartman <gregkh at suse dot de>, Thomas Gleixner <tglx at linutronix dot de>, William Cohen <wcohen at redhat dot com>, ltt-dev at shafik dot org, systemtap at sources dot redhat dot com, Alan Cox <alan at lxorguk dot ukuu dot org dot uk>
- Date: Fri, 22 Sep 2006 15:24:00 -0400
- Subject: Re: [PATCH] Linux Kernel Markers 0.5 for Linux 2.6.17 (with probe management)
- Organization: Opersys inc.
- References: <20060921160009.GA30115@Krystal> <20060921160656.GA24774@elte.hu> <20060921214248.GA10097@Krystal> <20060922070714.GB4167@elte.hu> <20060922150810.GB20839@Krystal> <45140E33.firstname.lastname@example.org> <20060922161353.GA1569@Krystal> <email@example.com> <20060922180654.GA12645@Krystal>
- Reply-to: karim at opersys dot com
Mathieu Desnoyers wrote:
> Here is the implementation :-)
Trigger happy :)
> To change it, we can dynamically overwrite the __mark_near_jump_select_##name
> value (a byte) to (__mark_jump_call_##name - __mark_near_jump_##name).
Hmm... I don't know if you won't still need to resort to int3 and
then overwrite the byte. From my understanding it sounds like you
wouldn't but that's where Richard's insight on the errata stuff
might come in handy.
Have you actually tried to run this code by any chance? *If* it did
work, I think this might just mean that you don't need either
kprobes or djprobes.
> So we have one architecture specific optimisation within the architecture
> agnostic marking mechanism.
That would seem reasonable, I think. You might want to test out
your mechanism, get confirmation from Richard and then post an
update to your patches.