linux-kernel - Re: [PATCH 5/7] ftrace, perf: Add support to use function tracepoint in perf

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Date:	Fri, 3 Feb 2012 13:54:13 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	rostedt@...dmis.org, mingo@...hat.com, paulus@...ba.org,
	acme@...stprotocols.net, a.p.zijlstra@...llo.nl,
	linux-kernel@...r.kernel.org, aarapov@...hat.com
Subject: Re: [PATCH 5/7] ftrace, perf: Add support to use function tracepoint
 in perf

On Thu, Feb 02, 2012 at 07:14:12PM +0100, Frederic Weisbecker wrote:
> On Sat, Jan 28, 2012 at 07:43:27PM +0100, Jiri Olsa wrote:
> > Adding perf registration support for the ftrace function event,
> > so it is now possible to register it via perf interface.
> > 
> > The perf_event struct statically contains ftrace_ops as a handle
> > for function tracer. The function tracer is registered/unregistered
> > in open/close actions.
> > 
> > To be efficient, we enable/disable ftrace_ops each time the traced

SNIP

> > +
> > +	return -EINVAL;
> > +}
> 
> All the above from perf_ftrace_function_call() to here should perhaps
> go to trace_function.c.

hm, I'd call it rather trace_perf_function.c 

> 
> > diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
> > index bbeec31..867653c 100644
> > --- a/kernel/trace/trace_export.c
> > +++ b/kernel/trace/trace_export.c
> > @@ -131,6 +131,28 @@ ftrace_define_fields_##name(struct ftrace_event_call *event_call)	\
> >  
> >  #include "trace_entries.h"
> >  
> > +static int ftrace_event_class_register(struct ftrace_event_call *call,
> > +				       enum trace_reg type, void *data)
> > +{
> > +	switch (type) {
> > +	case TRACE_REG_PERF_REGISTER:
> > +	case TRACE_REG_PERF_UNREGISTER:
> > +		return 0;
> > +	case TRACE_REG_PERF_OPEN:
> > +	case TRACE_REG_PERF_CLOSE:
> > +	case TRACE_REG_PERF_ADD:
> > +	case TRACE_REG_PERF_DEL:
> > +#ifdef CONFIG_PERF_EVENTS
> > +		return perf_ftrace_event_register(call, type, data);
> > +#endif
> > +	case TRACE_REG_REGISTER:
> > +	case TRACE_REG_UNREGISTER:
> > +		break;
> > +	}
> > +
> > +	return -EINVAL;
> > +}
> 
> Hmm, one day we'll need to demux here. What about adding an argument to
> FTRACE_ENTRY() to add the pointer to .reg ?

ok, would something like the attached change be ok?

thanks,
jirka


---
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 55c6ea0..638476a 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -68,6 +68,10 @@ enum trace_type {
 #undef FTRACE_ENTRY_DUP
 #define FTRACE_ENTRY_DUP(name, name_struct, id, tstruct, printk)
 
+#undef FTRACE_ENTRY_REG
+#define FTRACE_ENTRY_REG(name, struct_name, id, tstruct, print, regfn) \
+	FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print))
+
 #include "trace_entries.h"
 
 /*
diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
index bbeec31..f74de86 100644
--- a/kernel/trace/trace_export.c
+++ b/kernel/trace/trace_export.c
@@ -18,6 +18,14 @@
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM	ftrace
 
+/*
+ * The FTRACE_ENTRY_REG macro allows ftrace entry to define register
+ * function and thus become accesible via perf.
+ */
+#undef FTRACE_ENTRY_REG
+#define FTRACE_ENTRY_REG(name, struct_name, id, tstruct, print, regfn) \
+	FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print))
+
 /* not needed for this file */
 #undef __field_struct
 #define __field_struct(type, item)
@@ -152,13 +160,14 @@ ftrace_define_fields_##name(struct ftrace_event_call *event_call)	\
 #undef F_printk
 #define F_printk(fmt, args...) #fmt ", "  __stringify(args)
 
-#undef FTRACE_ENTRY
-#define FTRACE_ENTRY(call, struct_name, etype, tstruct, print)		\
+#undef FTRACE_ENTRY_REG
+#define FTRACE_ENTRY_REG(call, struct_name, etype, tstruct, print, regfn)\
 									\
 struct ftrace_event_class event_class_ftrace_##call = {			\
 	.system			= __stringify(TRACE_SYSTEM),		\
 	.define_fields		= ftrace_define_fields_##call,		\
 	.fields			= LIST_HEAD_INIT(event_class_ftrace_##call.fields),\
+	.reg			= regfn,				\
 };									\
 									\
 struct ftrace_event_call __used event_##call = {			\
@@ -170,4 +179,9 @@ struct ftrace_event_call __used event_##call = {			\
 struct ftrace_event_call __used						\
 __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call;
 
+#undef FTRACE_ENTRY
+#define FTRACE_ENTRY(call, struct_name, etype, tstruct, print)		\
+	FTRACE_ENTRY_REG(call, struct_name, etype,			\
+			 PARAMS(tstruct), PARAMS(print), NULL)
+
 #include "trace_entries.h"
--
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