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Re: [PATCH] Linux Kernel Markers
- From: Karim Yaghmour <karim at opersys dot com>
- To: Martin Bligh <mbligh at google dot com>
- Cc: Ingo Molnar <mingo at elte dot hu>, Mathieu Desnoyers <mathieu dot desnoyers at polymtl dot ca>, "Frank Ch. Eigler" <fche at redhat dot com>, 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>, Andrew Morton <akpm at osdl dot org>, 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: Tue, 19 Sep 2006 12:55:36 -0400
- Subject: Re: [PATCH] Linux Kernel Markers
- Organization: Opersys inc.
- References: <20060918234502.GA197@Krystal> <20060919081124.GA30394@elte.hu> <451008AC.6030006@google.com> <45101965.3050509@opersys.com> <45101809.5030906@google.com>
- Reply-to: karim at opersys dot com
Martin Bligh wrote:
> That was always the intent, or codebase + flat patch if really
> necessary. Sorry if that wasn't clear.
Actually rereading through your posts with this correction in mind
I find this to actually be one of the most interesting ideas I've
seen of late. There's probably not a 1-to-1 correlation here, but
some of the problems mentioned seem similar to RCU stuff (modify
pointer, make sure nobody's got copy to it, etc.), tough I could
be wrong.
Random thoughts -- no guarantees:
Instead of freezing everything and making sure all text refs to
function are modified, you might just be able to use kprobes (on
the architectures that have it) as a trampoline for on-the-fly
address call modifications. And on the archs that don't have
kprobes, you could at build time degrade this by replacing direct
calls to instrumented functions by function pointers or localized
ifs.
Not sure.
Karim