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Re: [PATCH -tip 0/4 V3] tracing: kprobe-based event tracer
- From: Ingo Molnar <mingo at elte dot hu>
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- Cc: Arnaldo Carvalho de Melo <acme at redhat dot com>, Steven Rostedt <rostedt at goodmis dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Frederic Weisbecker <fweisbec at gmail dot com>, Linux Kernel Mailing List <linux-kernel at vger dot kernel dot org>, systemtap-ml <systemtap at sources dot redhat dot com>, Andrew Morton <akpm at linux-foundation dot org>, Jim Keniston <jkenisto at us dot ibm dot com>
- Date: Wed, 1 Apr 2009 19:47:20 +0200
- Subject: Re: [PATCH -tip 0/4 V3] tracing: kprobe-based event tracer
- References: <49CC08A2.5030602@redhat.com> <20090401133654.GB18677@elte.hu> <49D37584.50208@redhat.com> <20090401142711.GG18677@elte.hu> <49D3A708.9080501@redhat.com>
* Masami Hiramatsu <mhiramat@redhat.com> wrote:
> >> I agreed. Fortunately, Jim Keniston and I wrote an x86
> >> instruction decoder :-) which has been made originally for
> >> uprobe andd kprobes jump-optimizer.
> >>
> >> https://www.redhat.com/archives/utrace-devel/2009-March/msg00031.html
> >
> > looks cool. Needs to be put somewhere in arch/x86/lib/, provided
> > as a generic facility, with a Kconfig variable that says that
> > the architecture supports it and then the kprobes-tracer could
> > make immediate use of it, right?
>
> Yeah, I'd rather add a safety checker in kprobes-x86 itself,
> because sometimes it has to fixup instructions modified by
> previous kprobes.
Oh, certainly! I didnt know how much you wanted to check things on
the kprobes side but by all means please add it there too, it will
be for the better.
A clear and actionable debug message to the syslog is important for
the case where the decoder rejects an action. This is especially
important for the kprobes side - we dont want silent breakage of
tools.
Ingo