tracing/syscalls: Add filtering support

Add filtering support for syscall events:

 # echo 'mode == 0666' > events/syscalls/sys_enter_open
 # echo 'ret == 0' > events/syscalls/sys_exit_open
 # echo 1 > events/syscalls/sys_enter_open
 # echo 1 > events/syscalls/sys_exit_open
 # cat trace
 ...
   modprobe-3084 [001] 117.463140: sys_open(filename: 917d3e8, flags: 0, mode: 1b6)
   modprobe-3084 [001] 117.463176: sys_open -> 0x0
       less-3086 [001] 117.510455: sys_open(filename: 9c6bdb8, flags: 8000, mode: 1b6)
   sendmail-2574 [001] 122.145840: sys_open(filename: b807a365, flags: 0, mode: 1b6)
 ...

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A8BAFCB.1040006@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 21 insertions, 7 deletions

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 427cbae47f84..df5b085c4150 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -140,8 +140,9 @@ extern int filter_current_check_discard(struct ftrace_event_call *call,
 					void *rec,
 					struct ring_buffer_event *event);
 
-extern int trace_define_field(struct ftrace_event_call *call, char *type,
-			      char *name, int offset, int size, int is_signed);
+extern int trace_define_field(struct ftrace_event_call *call,
+			      const char *type, const char *name,
+			      int offset, int size, int is_signed);
 extern int trace_define_common_fields(struct ftrace_event_call *call);
 
 #define is_signed_type(type)	(((type)(-1)) < 0)
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 8d57f77794ee..f124c8995555 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -190,6 +190,7 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
 		.event                  = &event_syscall_enter,		\
 		.raw_init		= init_enter_##sname,		\
 		.show_format		= syscall_enter_format,		\
+		.define_fields		= syscall_enter_define_fields,	\
 		.regfunc		= reg_event_syscall_enter,	\
 		.unregfunc		= unreg_event_syscall_enter,	\
 		.data			= "sys"#sname,			\
@@ -226,6 +227,7 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
 		.event                  = &event_syscall_exit,		\
 		.raw_init		= init_exit_##sname,		\
 		.show_format		= syscall_exit_format,		\
+		.define_fields		= syscall_exit_define_fields,	\
 		.regfunc		= reg_event_syscall_exit,	\
 		.unregfunc		= unreg_event_syscall_exit,	\
 		.data			= "sys"#sname,			\
@@ -233,6 +235,8 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
 	}
 
 #define SYSCALL_METADATA(sname, nb)				\
+	SYSCALL_TRACE_ENTER_EVENT(sname);			\
+	SYSCALL_TRACE_EXIT_EVENT(sname);			\
 	static const struct syscall_metadata __used		\
 	  __attribute__((__aligned__(4)))			\
 	  __attribute__((section("__syscalls_metadata")))	\
@@ -241,20 +245,22 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
 		.nb_args 	= nb,				\
 		.types		= types_##sname,		\
 		.args		= args_##sname,			\
-	};							\
-	SYSCALL_TRACE_ENTER_EVENT(sname);			\
-	SYSCALL_TRACE_EXIT_EVENT(sname);
+		.enter_event	= &event_enter_##sname,		\
+		.exit_event	= &event_exit_##sname,		\
+	};
 
 #define SYSCALL_DEFINE0(sname)					\
+	SYSCALL_TRACE_ENTER_EVENT(_##sname);			\
+	SYSCALL_TRACE_EXIT_EVENT(_##sname);			\
 	static const struct syscall_metadata __used		\
 	  __attribute__((__aligned__(4)))			\
 	  __attribute__((section("__syscalls_metadata")))	\
 	  __syscall_meta_##sname = {				\
 		.name 		= "sys_"#sname,			\
 		.nb_args 	= 0,				\
+		.enter_event	= &event_enter__##sname,	\
+		.exit_event	= &event_exit__##sname,		\
 	};							\
-	SYSCALL_TRACE_ENTER_EVENT(_##sname);			\
-	SYSCALL_TRACE_EXIT_EVENT(_##sname);			\
 	asmlinkage long sys_##sname(void)
 #else
 #define SYSCALL_DEFINE0(name)	   asmlinkage long sys_##name(void)
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 5ce85d75d31b..9661dd406b93 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -34,6 +34,8 @@ DECLARE_TRACE_WITH_CALLBACK(syscall_exit,
  * @args: list of args as strings (args[i] matches types[i])
  * @enter_id: associated ftrace enter event id
  * @exit_id: associated ftrace exit event id
+ * @enter_event: associated syscall_enter trace event
+ * @exit_event: associated syscall_exit trace event
  */
 struct syscall_metadata {
 	const char	*name;
@@ -42,6 +44,9 @@ struct syscall_metadata {
 	const char	**args;
 	int		enter_id;
 	int		exit_id;
+
+	struct ftrace_event_call *enter_event;
+	struct ftrace_event_call *exit_event;
 };
 
 #ifdef CONFIG_FTRACE_SYSCALLS
@@ -59,6 +64,8 @@ extern int syscall_enter_format(struct ftrace_event_call *call,
 				struct trace_seq *s);
 extern int syscall_exit_format(struct ftrace_event_call *call,
 				struct trace_seq *s);
+extern int syscall_enter_define_fields(struct ftrace_event_call *call);
+extern int syscall_exit_define_fields(struct ftrace_event_call *call);
 enum print_line_t print_syscall_enter(struct trace_iterator *iter, int flags);
 enum print_line_t print_syscall_exit(struct trace_iterator *iter, int flags);
 #endif