tracing: add event trace infrastructure

This patch creates the event tracing infrastructure of ftrace.
It will create the files:

 /debug/tracing/available_events
 /debug/tracing/set_event

The available_events will list the trace points that have been
registered with the event tracer.

set_events will allow the user to enable or disable an event hook.

example:

 # echo sched_wakeup > /debug/tracing/set_event

Will enable the sched_wakeup event (if it is registered).

 # echo "!sched_wakeup" >> /debug/tracing/set_event

Will disable the sched_wakeup event (and only that event).

 # echo > /debug/tracing/set_event

Will disable all events (notice the '>')

 # cat /debug/tracing/available_events > /debug/tracing/set_event

Will enable all registered event hooks.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index c61fab1dd2f8..0add6b28c366 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -61,6 +61,14 @@
 #define BRANCH_PROFILE()
 #endif
 
+#ifdef CONFIG_EVENT_TRACER
+#define FTRACE_EVENTS() VMLINUX_SYMBOL(__start_ftrace_events) = .;      \
+                        *(_ftrace_events)                               \
+                        VMLINUX_SYMBOL(__stop_ftrace_events) = .;
+#else
+#define FTRACE_EVENTS()
+#endif
+
 /* .data section */
 #define DATA_DATA                                                       \
         *(.data)                                                        \
@@ -81,7 +89,8 @@
         *(__tracepoints)                                                \
         VMLINUX_SYMBOL(__stop___tracepoints) = .;                       \
         LIKELY_PROFILE()                                                \
-        BRANCH_PROFILE()
+        BRANCH_PROFILE()                                                \
+        FTRACE_EVENTS()
 
 #define RO_DATA(align)                                                  \
         . = ALIGN((align));                                             \