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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: "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>, Ingo Molnar <mingo at elte dot hu>, Mathieu Desnoyers <mathieu dot desnoyers at polymtl dot ca>, 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>, Michael Davidson <md at google dot com>
- Date: Wed, 20 Sep 2006 15:58:01 -0400
- Subject: Re: [PATCH] Linux Kernel Markers
- Organization: Opersys inc.
- References: <4510151B.5070304@google.com> <20060919093935.4ddcefc3.akpm@osdl.org> <45101DBA.7000901@google.com> <20060919063821.GB23836@in.ibm.com> <45102641.7000101@google.com> <20060919070516.GD23836@in.ibm.com> <451030A6.6040801@google.com> <45105B5E.9080107@opersys.com> <451141B1.40803@hitachi.com> <451178B0.9030205@opersys.com> <20060920180808.GI18646@redhat.com> <451186F2.3060702@google.com> <45118D63.8070604@opersys.com> <451194DA.40300@google.com> <451199F4.3000006@opersys.com> <45119934.8080001@google.com>
- Reply-to: karim at opersys dot com
Martin Bligh wrote:
> You mean using the jump-over thing that was posted earlier?
> I thought the CPU erratas prevented doing that atomically
> properly. From my understanding of the last 24 hours discussion,
> it seemed like the ONLY thing we could do safely atomically was
> insert an int3. Which sucks, frankly, but still.
No. djprobes already does safely insert other stuff than just
int3, that's the whole point.
Here are the relevant postings by Hiramatsu-san:
http://marc.theaimsgroup.com/?l=linux-kernel&m=115875912510827&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m=115875867519302&w=2
Unless there's something *I* fundamentally misunderstood from
Hiramatsu-san's implementation and input, djprobes can replace
the 5-byte filler with a 5-byte unconditional jump. IOW your
mechanism works, no int3s involved.
Karim