Re: [PATCH -tip v14 08/12] tracing: add kprobe-based event tracer

From: Frederic Weisbecker <fweisbec@gmail.com>
To: Masami Hiramatsu <mhiramat@redhat.com>
Cc: "Ingo Molnar" <mingo@elte.hu>,
	"Steven Rostedt" <rostedt@goodmis.org>,
	lkml <linux-kernel@vger.kernel.org>,
	systemtap <systemtap@sources.redhat.com>,
	kvm <kvm@vger.kernel.org>,
	DLE <dle-develop@lists.sourceforge.net>,
	"Ananth N Mavinakayanahalli" <ananth@in.ibm.com>,
	"Avi Kivity" <avi@redhat.com>, "Andi Kleen" <ak@linux.intel.com>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Frank Ch. Eigler" <fche@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Jason Baron" <jbaron@redhat.com>,
	"Jim Keniston" <jkenisto@us.ibm.com>,
	"K.Prasad" <prasad@linux.vnet.ibm.com>,
	"Lai Jiangshan" <laijs@cn.fujitsu.com>,
	"Li Zefan" <lizf@cn.fujitsu.com>,
	PrzemysławPawełczyk <przemyslaw@pawelczyk.it>,
	"Roland McGrath" <roland@redhat.com>,
	"Sam Ravnborg" <sam@ravnborg.org>,
	"Srikar Dronamraju" <srikar@linux.vnet.ibm.com>,
	"Tom Zanussi" <tzanussi@gmail.com>,
	"Vegard Nossum" <vegard.nossum@gmail.com>
Subject: Re: [PATCH -tip v14 08/12] tracing: add kprobe-based event tracer
Date: Wed, 19 Aug 2009 03:23:08 +0200	[thread overview]
Message-ID: <20090819012306.GJ5231@nowhere> (raw)
In-Reply-To: <20090813203510.31965.29123.stgit@localhost.localdomain>

On Thu, Aug 13, 2009 at 04:35:11PM -0400, Masami Hiramatsu wrote:
> Add kprobes-based event tracer on ftrace.
> 
> This tracer is similar to the events tracer which is based on Tracepoint
> infrastructure. Instead of Tracepoint, this tracer is based on kprobes
> (kprobe and kretprobe). It probes anywhere where kprobes can probe(this
>  means, all functions body except for __kprobes functions).
> 
> Similar to the events tracer, this tracer doesn't need to be activated via
> current_tracer, instead of that, just set probe points via
> /sys/kernel/debug/tracing/kprobe_events. And you can set filters on each
> probe events via /sys/kernel/debug/tracing/events/kprobes/<EVENT>/filter.
> 
> This tracer supports following probe arguments for each probe.
> 
>   %REG  : Fetch register REG
>   sN    : Fetch Nth entry of stack (N >= 0)
>   sa    : Fetch stack address.
>   @ADDR : Fetch memory at ADDR (ADDR should be in kernel)
>   @SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
>   aN    : Fetch function argument. (N >= 0)
>   rv    : Fetch return value.
>   ra    : Fetch return address.
>   +|-offs(FETCHARG) : fetch memory at FETCHARG +|- offs address.
> 
> See Documentation/trace/kprobetrace.txt for details.
> 
> Changes from v13:
>  - Support 'sa' for stack address.
>  - Use call->data instead of container_of() macro.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> Cc: Avi Kivity <avi@redhat.com>
> Cc: Andi Kleen <ak@linux.intel.com>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Frank Ch. Eigler <fche@redhat.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: H. Peter Anvin <hpa@zytor.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Jason Baron <jbaron@redhat.com>
> Cc: Jim Keniston <jkenisto@us.ibm.com>
> Cc: K.Prasad <prasad@linux.vnet.ibm.com>
> Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
> Cc: Li Zefan <lizf@cn.fujitsu.com>
> Cc: Przemysław Pawełczyk <przemyslaw@pawelczyk.it>
> Cc: Roland McGrath <roland@redhat.com>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Tom Zanussi <tzanussi@gmail.com>
> Cc: Vegard Nossum <vegard.nossum@gmail.com>
> ---
> 
>  Documentation/trace/kprobetrace.txt |  139 ++++

I'll probably split this commit to have the first version of the
documentation as a separate patch in order to lighten this.

Frederic.