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.

[[email protected]: Fixed conflict against latest tracing/core]

Signed-off-by: Masami Hiramatsu <[email protected]>
Acked-by: Ananth N Mavinakayanahalli <[email protected]>
Cc: Avi Kivity <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Frank Ch. Eigler <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jason Baron <[email protected]>
Cc: Jim Keniston <[email protected]>
Cc: K.Prasad <[email protected]>
Cc: Lai Jiangshan <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Przemysław Pawełczyk <[email protected]>
Cc: Roland McGrath <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Cc: Srikar Dronamraju <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Tom Zanussi <[email protected]>
Cc: Vegard Nossum <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>

Author: Masami Hiramatsu

kernel/trace/Kconfig

@@ -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

@@ -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

@@ -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

@@ -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