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Commit 77b44d1b authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

tracing/kprobes: Rename Kprobe-tracer to kprobe-event 



Rename Kprobes-based event tracer to kprobes-based tracing event
(kprobe-event), since it is not a tracer but an extensible
tracing event interface.

This also changes CONFIG_KPROBE_TRACER to CONFIG_KPROBE_EVENT
and sets it y by default.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
LKML-Reference: <20091104001247.3454.14131.stgit@harusame>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 91365bbe

Documentation/trace/kprobetrace.txt

+16 −18
Original line number Diff line number Diff line 
                        Kprobe-based Event Tracer

                         =========================

                        Kprobe-based Event Tracing

                        ==========================



                 Documentation is written by Masami Hiramatsu





Overview

--------

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).

These events are similar to tracepoint based events. Instead of Tracepoint,

this is based on kprobes (kprobe and kretprobe). So it can probe wherever

kprobes can probe (this means, all functions body except for __kprobes

functions). Unlike the Tracepoint based event, this can be added and removed

dynamically, on the fly.



Unlike the function tracer, this tracer can probe instructions inside of

kernel functions. It allows you to check which instruction has been executed.

To enable this feature, build your kernel with CONFIG_KPROBE_TRACING=y.



Unlike the Tracepoint based events tracer, this tracer can add and remove

probe points on the fly.



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.

Similar to the events tracer, this doesn't need to be activated via

current_tracer. Instead of that, add probe points via

/sys/kernel/debug/tracing/kprobe_events, and enable it via

/sys/kernel/debug/tracing/events/kprobes/<EVENT>/enabled.





Synopsis of kprobe_events
@@ -55,9 +52,9 @@ Per-Probe Event Filtering 
-------------------------

 Per-probe event filtering feature allows you to set different filter on each

probe and gives you what arguments will be shown in trace buffer. If an event

name is specified right after 'p:' or 'r:' in kprobe_events, the tracer adds

an event under tracing/events/kprobes/<EVENT>, at the directory you can see

'id', 'enabled', 'format' and 'filter'.

name is specified right after 'p:' or 'r:' in kprobe_events, it adds an event

under tracing/events/kprobes/<EVENT>, at the directory you can see 'id',

'enabled', 'format' and 'filter'.



enabled:

  You can enable/disable the probe by writing 1 or 0 on it.
@@ -71,6 +68,7 @@ filter: 
id:

  This shows the id of this probe event.





Event Profiling

---------------

 You can check the total number of probe hits and probe miss-hits via

kernel/trace/Kconfig

+12 −7
Original line number Diff line number Diff line
@@ -428,17 +428,22 @@ config BLK_DEV_IO_TRACE 


	  If unsure, say N.



config KPROBE_TRACER

config KPROBE_EVENT

	depends on KPROBES

	depends on X86

	bool "Trace kprobes"

	bool "Enable kprobes-based dynamic events"

	select TRACING

	select GENERIC_TRACER

	default y

	help

	  This tracer probes everywhere where kprobes can probe it, and

	  records various registers and memories specified by user.

	  This also allows you to trace kprobe probe points as a dynamic

	  defined events. It provides per-probe event filtering interface.

	  This allows the user to add tracing events (similar to tracepoints) on the fly

	  via the ftrace interface. See Documentation/trace/kprobetrace.txt

	  for more details.



	  Those events can be inserted wherever kprobes can probe, and record

	  various register and memory values.



	  This option is also required by perf-probe subcommand of perf tools. If

	  you want to use perf tools, this option is strongly recommended.



config DYNAMIC_FTRACE

	bool "enable/disable ftrace tracepoints dynamically"

kernel/trace/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -53,7 +53,7 @@ obj-$(CONFIG_EVENT_TRACING) += trace_export.o 
obj-$(CONFIG_FTRACE_SYSCALLS) += trace_syscalls.o

obj-$(CONFIG_EVENT_PROFILE) += trace_event_profile.o

obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o

obj-$(CONFIG_KPROBE_TRACER) += trace_kprobe.o

obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o

obj-$(CONFIG_EVENT_TRACING) += power-traces.o



libftrace-y := ftrace.o

kernel/trace/trace_kprobe.c

+2 −4
Original line number Diff line number Diff line 
/*

 * kprobe based kernel tracer

 * Kprobes-based tracing events

 *

 * Created by Masami Hiramatsu <mhiramat@redhat.com>

 *
@@ -57,8 +57,6 @@ const char *reserved_field_names[] = { 
	FIELD_STRING_FUNC,

};



/* currently, trace_kprobe only supports X86. */



struct fetch_func {

	unsigned long (*func)(struct pt_regs *, void *);

	void *data;
@@ -191,7 +189,7 @@ static __kprobes void free_indirect_fetch_data(struct indirect_fetch_data *data) 
}



/**

 * Kprobe tracer core functions

 * Kprobe event core functions

 */



struct probe_arg {