ftrace: event profile hooks

Impact: new tracing infrastructure feature

Provide infrastructure to generate software perf counter events
from tracepoints.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090319194233.557364871@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

6 files changed, 89 insertions, 8 deletions

diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index c3feea01c3e0..0e45c206c2f9 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -44,5 +44,6 @@ obj-$(CONFIG_EVENT_TRACER) += trace_events.o
 obj-$(CONFIG_EVENT_TRACER) += events.o
 obj-$(CONFIG_EVENT_TRACER) += trace_export.o
 obj-$(CONFIG_FTRACE_SYSCALLS) += trace_syscalls.o
+obj-$(CONFIG_EVENT_PROFILE) += trace_event_profile.o
 
 libftrace-y := ftrace.o
diff --git a/kernel/trace/events.c b/kernel/trace/events.c
index 9fc918da404f..246f2aa6dc46 100644
--- a/kernel/trace/events.c
+++ b/kernel/trace/events.c
@@ -12,4 +12,3 @@
 #include "trace_events_stage_2.h"
 #include "trace_events_stage_3.h"
 
-#include <trace/trace_event_types.h>
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 7c9a0cbf5dca..7cfb741be200 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -785,12 +785,23 @@ struct ftrace_event_call {
         int             id;
         int             (*raw_init)(void);
         int             (*show_format)(struct trace_seq *s);
+
+#ifdef CONFIG_EVENT_PROFILE
+        atomic_t        profile_count;
+        int             (*profile_enable)(struct ftrace_event_call *);
+        void            (*profile_disable)(struct ftrace_event_call *);
+#endif
 };
 
 void event_trace_printk(unsigned long ip, const char *fmt, ...);
 extern struct ftrace_event_call __start_ftrace_events[];
 extern struct ftrace_event_call __stop_ftrace_events[];
 
+#define for_each_event(event)                                           \
+        for (event = __start_ftrace_events;                             \
+             (unsigned long)event < (unsigned long)__stop_ftrace_events; \
+             event++)
+
 extern const char *__start___trace_bprintk_fmt[];
 extern const char *__stop___trace_bprintk_fmt[];
 
diff --git a/kernel/trace/trace_event_profile.c b/kernel/trace/trace_event_profile.c
new file mode 100644
index 000000000000..22cba9970776
--- /dev/null
+++ b/kernel/trace/trace_event_profile.c
@@ -0,0 +1,31 @@
+/*
+ * trace event based perf counter profiling
+ *
+ * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
+ *
+ */
+
+#include "trace.h"
+
+int ftrace_profile_enable(int event_id)
+{
+        struct ftrace_event_call *event;
+
+        for_each_event(event) {
+                if (event->id == event_id)
+                        return event->profile_enable(event);
+        }
+
+        return -EINVAL;
+}
+
+void ftrace_profile_disable(int event_id)
+{
+        struct ftrace_event_call *event;
+
+        for_each_event(event) {
+                if (event->id == event_id)
+                        return event->profile_disable(event);
+        }
+}
+
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 7763db8fd0b3..3047b56f6637 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -19,11 +19,6 @@
 
 static DEFINE_MUTEX(event_mutex);
 
-#define events_for_each(event)                                          \
-        for (event = __start_ftrace_events;                             \
-             (unsigned long)event < (unsigned long)__stop_ftrace_events; \
-             event++)
-
 static void ftrace_clear_events(void)
 {
         struct ftrace_event_call *call = (void *)__start_ftrace_events;
@@ -90,7 +85,7 @@ static int ftrace_set_clr_event(char *buf, int set)
         }
 
         mutex_lock(&event_mutex);
-        events_for_each(call) {
+        for_each_event(call) {
 
                 if (!call->name || !call->regfunc)
                         continue;
@@ -628,7 +623,7 @@ static __init int event_trace_init(void)
         if (!d_events)
                 return 0;
 
-        events_for_each(call) {
+        for_each_event(call) {
                 /* The linker may leave blanks */
                 if (!call->name)
                         continue;
diff --git a/kernel/trace/trace_events_stage_3.h b/kernel/trace/trace_events_stage_3.h
index 4c26d97b4508..6b3261ca988c 100644
--- a/kernel/trace/trace_events_stage_3.h
+++ b/kernel/trace/trace_events_stage_3.h
@@ -109,6 +109,40 @@
 #undef TP_FMT
 #define TP_FMT(fmt, args...)    fmt "\n", ##args
 
+#ifdef CONFIG_EVENT_PROFILE
+#define _TRACE_PROFILE(call, proto, args)                               \
+static void ftrace_profile_##call(proto)                                \
+{                                                                       \
+        extern void perf_tpcounter_event(int);                          \
+        perf_tpcounter_event(event_##call.id);                          \
+}                                                                       \
+                                                                        \
+static int ftrace_profile_enable_##call(struct ftrace_event_call *call) \
+{                                                                       \
+        int ret = 0;                                                    \
+                                                                        \
+        if (!atomic_inc_return(&call->profile_count))                   \
+                ret = register_trace_##call(ftrace_profile_##call);     \
+                                                                        \
+        return ret;                                                     \
+}                                                                       \
+                                                                        \
+static void ftrace_profile_disable_##call(struct ftrace_event_call *call) \
+{                                                                       \
+        if (atomic_add_negative(-1, &call->profile_count))              \
+                unregister_trace_##call(ftrace_profile_##call);         \
+}
+
+#define _TRACE_PROFILE_INIT(call)                                       \
+        .profile_count = ATOMIC_INIT(-1),                               \
+        .profile_enable = ftrace_profile_enable_##call,                 \
+        .profile_disable = ftrace_profile_disable_##call,
+
+#else
+#define _TRACE_PROFILE(call, proto, args)
+#define _TRACE_PROFILE_INIT(call)
+#endif
+
 #define _TRACE_FORMAT(call, proto, args, fmt)                           \
 static void ftrace_event_##call(proto)                                  \
 {                                                                       \
@@ -147,6 +181,7 @@ static int ftrace_init_event_##call(void)				\
 #undef TRACE_FORMAT
 #define TRACE_FORMAT(call, proto, args, fmt)                            \
 _TRACE_FORMAT(call, PARAMS(proto), PARAMS(args), PARAMS(fmt))           \
+_TRACE_PROFILE(call, PARAMS(proto), PARAMS(args))                       \
 static struct ftrace_event_call __used                                  \
 __attribute__((__aligned__(4)))                                         \
 __attribute__((section("_ftrace_events"))) event_##call = {             \
@@ -155,6 +190,7 @@ __attribute__((section("_ftrace_events"))) event_##call = {		\
         .raw_init               = ftrace_init_event_##call,             \
         .regfunc                = ftrace_reg_event_##call,              \
         .unregfunc              = ftrace_unreg_event_##call,            \
+        _TRACE_PROFILE_INIT(call)                                       \
 }
 
 #undef __entry
@@ -162,6 +198,7 @@ __attribute__((section("_ftrace_events"))) event_##call = {		\
 
 #undef TRACE_EVENT
 #define TRACE_EVENT(call, proto, args, tstruct, assign, print)          \
+_TRACE_PROFILE(call, PARAMS(proto), PARAMS(args))                       \
                                                                         \
 static struct ftrace_event_call event_##call;                           \
                                                                         \
@@ -227,4 +264,11 @@ __attribute__((section("_ftrace_events"))) event_##call = {		\
         .regfunc                = ftrace_raw_reg_event_##call,          \
         .unregfunc              = ftrace_raw_unreg_event_##call,        \
         .show_format            = ftrace_format_##call,                 \
+        _TRACE_PROFILE_INIT(call)                                       \
 }
+
+#include <trace/trace_event_types.h>
+
+#undef _TRACE_PROFILE
+#undef _TRACE_PROFILE_INIT
+