tracing: Add trace events for each syscall entry/exit

Layer Frederic's syscall tracer on tracepoints. We create trace events
via hooking into the SYSCALL_DEFINE macros. This allows us to
individually toggle syscall entry and exit points on/off.

Signed-off-by: Jason Baron <jbaron@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

2 files changed, 68 insertions, 11 deletions

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 80de7003d8c..5e5b4d33a31 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -64,6 +64,7 @@ struct perf_counter_attr;
 #include <linux/sem.h>
 #include <asm/siginfo.h>
 #include <asm/signal.h>
+#include <linux/unistd.h>
 #include <linux/quota.h>
 #include <linux/key.h>
 #include <trace/syscall.h>
@@ -112,6 +113,59 @@ struct perf_counter_attr;
 #define __SC_STR_TDECL5(t, a, ...)	#t, __SC_STR_TDECL4(__VA_ARGS__)
 #define __SC_STR_TDECL6(t, a, ...)	#t, __SC_STR_TDECL5(__VA_ARGS__)
 
+
+#define SYSCALL_TRACE_ENTER_EVENT(sname)				\
+	static struct ftrace_event_call event_enter_##sname;		\
+	static int init_enter_##sname(void)				\
+	{								\
+		int num;						\
+		num = syscall_name_to_nr("sys"#sname);			\
+		if (num < 0)						\
+			return -ENOSYS;					\
+		register_ftrace_event(&event_syscall_enter);		\
+		INIT_LIST_HEAD(&event_enter_##sname.fields);		\
+		init_preds(&event_enter_##sname);			\
+		return 0;						\
+	}								\
+	static struct ftrace_event_call __used				\
+	  __attribute__((__aligned__(4)))				\
+	  __attribute__((section("_ftrace_events")))			\
+	  event_enter_##sname = {					\
+		.name                   = "sys_enter"#sname,		\
+		.system                 = "syscalls",			\
+		.event                  = &event_syscall_enter,		\
+		.raw_init		= init_enter_##sname,		\
+		.regfunc		= reg_event_syscall_enter,	\
+		.unregfunc		= unreg_event_syscall_enter,	\
+		.data			= "sys"#sname,			\
+	}
+
+#define SYSCALL_TRACE_EXIT_EVENT(sname)					\
+	static struct ftrace_event_call event_exit_##sname;		\
+	static int init_exit_##sname(void)				\
+	{								\
+		int num;						\
+		num = syscall_name_to_nr("sys"#sname);			\
+		if (num < 0)						\
+			return -ENOSYS;					\
+		register_ftrace_event(&event_syscall_exit);		\
+		INIT_LIST_HEAD(&event_exit_##sname.fields);		\
+		init_preds(&event_exit_##sname);			\
+		return 0;						\
+	}								\
+	static struct ftrace_event_call __used				\
+	  __attribute__((__aligned__(4)))				\
+	  __attribute__((section("_ftrace_events")))			\
+	  event_exit_##sname = {					\
+		.name                   = "sys_exit"#sname,		\
+		.system                 = "syscalls",			\
+		.event                  = &event_syscall_exit,		\
+		.raw_init		= init_exit_##sname,		\
+		.regfunc		= reg_event_syscall_exit,	\
+		.unregfunc		= unreg_event_syscall_exit,	\
+		.data			= "sys"#sname,			\
+	}
+
 #define SYSCALL_METADATA(sname, nb)				\
 	static const struct syscall_metadata __used		\
 	  __attribute__((__aligned__(4)))			\
@@ -121,7 +175,9 @@ struct perf_counter_attr;
 		.nb_args 	= nb,				\
 		.types		= types_##sname,		\
 		.args		= args_##sname,			\
-	}
+	};							\
+	SYSCALL_TRACE_ENTER_EVENT(sname);			\
+	SYSCALL_TRACE_EXIT_EVENT(sname);
 
 #define SYSCALL_DEFINE0(sname)					\
 	static const struct syscall_metadata __used		\
@@ -131,8 +187,9 @@ struct perf_counter_attr;
 		.name 		= "sys_"#sname,			\
 		.nb_args 	= 0,				\
 	};							\
+	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)
 #endif
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 3951d774de1..73fb8b4a995 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -2,6 +2,8 @@
 #define _TRACE_SYSCALL_H
 
 #include <linux/tracepoint.h>
+#include <linux/unistd.h>
+#include <linux/ftrace_event.h>
 
 #include <asm/ptrace.h>
 
@@ -40,15 +42,13 @@ struct syscall_metadata {
 
 #ifdef CONFIG_FTRACE_SYSCALLS
 extern struct syscall_metadata *syscall_nr_to_meta(int nr);
-extern void start_ftrace_syscalls(void);
-extern void stop_ftrace_syscalls(void);
-extern void ftrace_syscall_enter(struct pt_regs *regs);
-extern void ftrace_syscall_exit(struct pt_regs *regs);
-#else
-static inline void start_ftrace_syscalls(void)			{ }
-static inline void stop_ftrace_syscalls(void)			{ }
-static inline void ftrace_syscall_enter(struct pt_regs *regs)	{ }
-static inline void ftrace_syscall_exit(struct pt_regs *regs)	{ }
+extern int syscall_name_to_nr(char *name);
+extern struct trace_event event_syscall_enter;
+extern struct trace_event event_syscall_exit;
+extern int reg_event_syscall_enter(void *ptr);
+extern void unreg_event_syscall_enter(void *ptr);
+extern int reg_event_syscall_exit(void *ptr);
+extern void unreg_event_syscall_exit(void *ptr);
 #endif
 
 #endif /* _TRACE_SYSCALL_H */