tracing/ftrace: syscall tracing infrastructure, basics

Provide basic callbacks to do syscall tracing.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <1236401580-5758-2-git-send-email-fweisbec@gmail.com>
[ simplified it to a trace_printk() for now. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 8e4a2a6..95a0ad1 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -34,6 +34,9 @@
 config HAVE_HW_BRANCH_TRACER
 	bool
 
+config HAVE_FTRACE_SYSCALLS
+	bool
+
 config TRACER_MAX_TRACE
 	bool
 
@@ -175,6 +178,13 @@
 	  allowing the user to pick and choose which trace point they
 	  want to trace.
 
+config FTRACE_SYSCALLS
+	bool "Trace syscalls"
+	depends on HAVE_FTRACE_SYSCALLS
+	select TRACING
+	help
+	  Basic tracer to catch the syscall entry and exit events.
+
 config BOOT_TRACER
 	bool "Trace boot initcalls"
 	select TRACING