Commit 413d37d1 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Frederic Weisbecker
Browse files

tracing: Add kprobe-based event tracer 



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 in the next patch for details.

Changes from v13:
 - Support 'sa' for stack address.
 - Use call->data instead of container_of() macro.

[fweisbec@gmail.com: Fixed conflict against latest tracing/core]

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
Acked-by: default avatarAnanth 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: 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>
LKML-Reference: <20090813203510.31965.29123.stgit@localhost.localdomain>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent d93f12f3

kernel/trace/Kconfig

+12 −0
Original line number Diff line number Diff line
@@ -411,6 +411,18 @@ config BLK_DEV_IO_TRACE 


	  If unsure, say N.



config KPROBE_TRACER

	depends on KPROBES

	depends on X86

	bool "Trace kprobes"

	select TRACING

	select GENERIC_TRACER

	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.



config DYNAMIC_FTRACE

	bool "enable/disable ftrace tracepoints dynamically"

	depends on FUNCTION_TRACER

kernel/trace/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -54,5 +54,6 @@ 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



libftrace-y := ftrace.o

kernel/trace/trace.h

+30 −0
Original line number Diff line number Diff line
@@ -38,6 +38,8 @@ enum trace_type { 
	TRACE_KMEM_FREE,

	TRACE_POWER,

	TRACE_BLK,

	TRACE_KPROBE,

	TRACE_KRETPROBE,



	__TRACE_LAST_TYPE,

};
@@ -205,6 +207,30 @@ struct syscall_trace_exit { 
	unsigned long		ret;

};



struct kprobe_trace_entry {

	struct trace_entry	ent;

	unsigned long		ip;

	int			nargs;

	unsigned long		args[];

};



#define SIZEOF_KPROBE_TRACE_ENTRY(n)			\

	(offsetof(struct kprobe_trace_entry, args) +	\

	(sizeof(unsigned long) * (n)))



struct kretprobe_trace_entry {

	struct trace_entry	ent;

	unsigned long		func;

	unsigned long		ret_ip;

	int			nargs;

	unsigned long		args[];

};



#define SIZEOF_KRETPROBE_TRACE_ENTRY(n)			\

	(offsetof(struct kretprobe_trace_entry, args) +	\

	(sizeof(unsigned long) * (n)))







/*

 * trace_flag_type is an enumeration that holds different
@@ -317,6 +343,10 @@ extern void __ftrace_bad_type(void); 
			  TRACE_KMEM_ALLOC);	\

		IF_ASSIGN(var, ent, struct kmemtrace_free_entry,	\

			  TRACE_KMEM_FREE);	\

		IF_ASSIGN(var, ent, struct kprobe_trace_entry,		\

			  TRACE_KPROBE);				\

		IF_ASSIGN(var, ent, struct kretprobe_trace_entry,	\

			  TRACE_KRETPROBE);				\

		__ftrace_bad_type();					\

	} while (0)

kernel/trace/trace_event_types.h

+18 −0
Original line number Diff line number Diff line
@@ -175,4 +175,22 @@ TRACE_EVENT_FORMAT(kmem_free, TRACE_KMEM_FREE, kmemtrace_free_entry, ignore, 
	TP_RAW_FMT("type:%u call_site:%lx ptr:%p")

);



TRACE_EVENT_FORMAT(kprobe, TRACE_KPROBE, kprobe_trace_entry, ignore,

	TRACE_STRUCT(

		TRACE_FIELD(unsigned long, ip, ip)

		TRACE_FIELD(int, nargs, nargs)

		TRACE_FIELD_ZERO(unsigned long, args)

	),

	TP_RAW_FMT("%08lx: args:0x%lx ...")

);



TRACE_EVENT_FORMAT(kretprobe, TRACE_KRETPROBE, kretprobe_trace_entry, ignore,

	TRACE_STRUCT(

		TRACE_FIELD(unsigned long, func, func)

		TRACE_FIELD(unsigned long, ret_ip, ret_ip)

		TRACE_FIELD(int, nargs, nargs)

		TRACE_FIELD_ZERO(unsigned long, args)

	),

	TP_RAW_FMT("%08lx <- %08lx: args:0x%lx ...")

);

#undef TRACE_SYSTEM

kernel/trace/trace_kprobe.c

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+1202 −0

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