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tracing: Remove per event trace registering
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This patch removes the register functions of TRACE_EVENT() to enable
and disable tracepoints. The registering of a event is now down
directly in the trace_events.c file. The tracepoint_probe_register()
is now called directly.

The prototypes are no longer type checked, but this should not be
an issue since the tracepoints are created automatically by the
macros. If a prototype is incorrect in the TRACE_EVENT() macro, then
other macros will catch it.

The trace_event_class structure now holds the probes to be called
by the callbacks. This removes needing to have each event have
a separate pointer for the probe.

To handle kprobes and syscalls, since they register probes in a
different manner, a "reg" field is added to the ftrace_event_class
structure. If the "reg" field is assigned, then it will be called for
enabling and disabling of the probe for either ftrace or perf. To let
the reg function know what is happening, a new enum (trace_reg) is
created that has the type of control that is needed.

With this new rework, the 82 kernel events and 618 syscall events
has their footprint dramatically lowered:

   text	   data	    bss	    dec	    hex	filename
4913961	1088356	 861512	6863829	 68bbd5	vmlinux.orig
4914025	1088868	 861512	6864405	 68be15	vmlinux.class
4918492	1084612	 861512	6864616	 68bee8	vmlinux.tracepoint
4900252	1057412	 861512	6819176	 680d68	vmlinux.regs

The size went from 6863829 to 6819176, that's a total of 44K
in savings. With tracepoints being continuously added, this is
critical that the footprint becomes minimal.

v5: Added #ifdef CONFIG_PERF_EVENTS around a reference to perf
    specific structure in trace_events.c.

v4: Fixed trace self tests to check probe because regfunc no longer
    exists.

v3: Updated to handle void *data in beginning of probe parameters.
    Also added the tracepoint: check_trace_callback_type_##call().

v2: Changed the callback probes to pass void * and typecast the
    value within the function.

Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Steven Rostedt authored and Steven Rostedt committed May 14, 2010
1 parent 38516ab commit 2239291
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Showing 7 changed files with 171 additions and 147 deletions.
19 changes: 15 additions & 4 deletions include/linux/ftrace_event.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -113,8 +113,23 @@ void tracing_record_cmdline(struct task_struct *tsk);

struct event_filter;

enum trace_reg {
TRACE_REG_REGISTER,
TRACE_REG_UNREGISTER,
TRACE_REG_PERF_REGISTER,
TRACE_REG_PERF_UNREGISTER,
};

struct ftrace_event_call;

struct ftrace_event_class {
char *system;
void *probe;
#ifdef CONFIG_PERF_EVENTS
void *perf_probe;
#endif
int (*reg)(struct ftrace_event_call *event,
enum trace_reg type);
};

struct ftrace_event_call {
Expand All @@ -124,8 +139,6 @@ struct ftrace_event_call {
struct dentry *dir;
struct trace_event *event;
int enabled;
int (*regfunc)(struct ftrace_event_call *);
void (*unregfunc)(struct ftrace_event_call *);
int id;
const char *print_fmt;
int (*raw_init)(struct ftrace_event_call *);
Expand All @@ -137,8 +150,6 @@ struct ftrace_event_call {
void *data;

int perf_refcount;
int (*perf_event_enable)(struct ftrace_event_call *);
void (*perf_event_disable)(struct ftrace_event_call *);
};

#define PERF_MAX_TRACE_SIZE 2048
Expand Down
29 changes: 4 additions & 25 deletions include/linux/syscalls.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -103,22 +103,6 @@ struct perf_event_attr;
#define __SC_TEST5(t5, a5, ...) __SC_TEST(t5); __SC_TEST4(__VA_ARGS__)
#define __SC_TEST6(t6, a6, ...) __SC_TEST(t6); __SC_TEST5(__VA_ARGS__)

#ifdef CONFIG_PERF_EVENTS

#define TRACE_SYS_ENTER_PERF_INIT(sname) \
.perf_event_enable = perf_sysenter_enable, \
.perf_event_disable = perf_sysenter_disable,

#define TRACE_SYS_EXIT_PERF_INIT(sname) \
.perf_event_enable = perf_sysexit_enable, \
.perf_event_disable = perf_sysexit_disable,
#else
#define TRACE_SYS_ENTER_PERF(sname)
#define TRACE_SYS_ENTER_PERF_INIT(sname)
#define TRACE_SYS_EXIT_PERF(sname)
#define TRACE_SYS_EXIT_PERF_INIT(sname)
#endif /* CONFIG_PERF_EVENTS */

#ifdef CONFIG_FTRACE_SYSCALLS
#define __SC_STR_ADECL1(t, a) #a
#define __SC_STR_ADECL2(t, a, ...) #a, __SC_STR_ADECL1(__VA_ARGS__)
Expand All @@ -134,7 +118,8 @@ struct perf_event_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__)

extern struct ftrace_event_class event_class_syscalls;
extern struct ftrace_event_class event_class_syscall_enter;
extern struct ftrace_event_class event_class_syscall_exit;

#define SYSCALL_TRACE_ENTER_EVENT(sname) \
static const struct syscall_metadata __syscall_meta_##sname; \
Expand All @@ -148,14 +133,11 @@ extern struct ftrace_event_class event_class_syscalls;
__attribute__((section("_ftrace_events"))) \
event_enter_##sname = { \
.name = "sys_enter"#sname, \
.class = &event_class_syscalls, \
.class = &event_class_syscall_enter, \
.event = &enter_syscall_print_##sname, \
.raw_init = init_syscall_trace, \
.define_fields = syscall_enter_define_fields, \
.regfunc = reg_event_syscall_enter, \
.unregfunc = unreg_event_syscall_enter, \
.data = (void *)&__syscall_meta_##sname,\
TRACE_SYS_ENTER_PERF_INIT(sname) \
}

#define SYSCALL_TRACE_EXIT_EVENT(sname) \
Expand All @@ -170,14 +152,11 @@ extern struct ftrace_event_class event_class_syscalls;
__attribute__((section("_ftrace_events"))) \
event_exit_##sname = { \
.name = "sys_exit"#sname, \
.class = &event_class_syscalls, \
.class = &event_class_syscall_exit, \
.event = &exit_syscall_print_##sname, \
.raw_init = init_syscall_trace, \
.define_fields = syscall_exit_define_fields, \
.regfunc = reg_event_syscall_exit, \
.unregfunc = unreg_event_syscall_exit, \
.data = (void *)&__syscall_meta_##sname,\
TRACE_SYS_EXIT_PERF_INIT(sname) \
}

#define SYSCALL_METADATA(sname, nb) \
Expand Down
133 changes: 38 additions & 95 deletions include/trace/ftrace.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -381,53 +381,6 @@ static inline notrace int ftrace_get_offsets_##call( \

#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)

#ifdef CONFIG_PERF_EVENTS

/*
* Generate the functions needed for tracepoint perf_event support.
*
* NOTE: The insertion profile callback (ftrace_profile_<call>) is defined later
*
* static int ftrace_profile_enable_<call>(void)
* {
* return register_trace_<call>(ftrace_profile_<call>);
* }
*
* static void ftrace_profile_disable_<call>(void)
* {
* unregister_trace_<call>(ftrace_profile_<call>);
* }
*
*/

#undef DECLARE_EVENT_CLASS
#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)

#undef DEFINE_EVENT
#define DEFINE_EVENT(template, name, proto, args) \
\
static void perf_trace_##name(void *, proto); \
\
static notrace int \
perf_trace_enable_##name(struct ftrace_event_call *unused) \
{ \
return register_trace_##name(perf_trace_##name, NULL); \
} \
\
static notrace void \
perf_trace_disable_##name(struct ftrace_event_call *unused) \
{ \
unregister_trace_##name(perf_trace_##name, NULL); \
}

#undef DEFINE_EVENT_PRINT
#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args))

#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)

#endif /* CONFIG_PERF_EVENTS */

/*
* Stage 4 of the trace events.
*
Expand All @@ -437,8 +390,9 @@ perf_trace_disable_##name(struct ftrace_event_call *unused) \
*
* static struct ftrace_event_call event_<call>;
*
* static void ftrace_raw_event_<call>(proto)
* static void ftrace_raw_event_<call>(void *__data, proto)
* {
* struct ftrace_event_call *event_call = __data;
* struct ftrace_data_offsets_<call> __maybe_unused __data_offsets;
* struct ring_buffer_event *event;
* struct ftrace_raw_<call> *entry; <-- defined in stage 1
Expand Down Expand Up @@ -468,16 +422,6 @@ perf_trace_disable_##name(struct ftrace_event_call *unused) \
* event, irq_flags, pc);
* }
*
* static int ftrace_raw_reg_event_<call>(struct ftrace_event_call *unused)
* {
* return register_trace_<call>(ftrace_raw_event_<call>);
* }
*
* static void ftrace_unreg_event_<call>(struct ftrace_event_call *unused)
* {
* unregister_trace_<call>(ftrace_raw_event_<call>);
* }
*
* static struct trace_event ftrace_event_type_<call> = {
* .trace = ftrace_raw_output_<call>, <-- stage 2
* };
Expand All @@ -504,11 +448,15 @@ perf_trace_disable_##name(struct ftrace_event_call *unused) \

#ifdef CONFIG_PERF_EVENTS

#define _TRACE_PERF_PROTO(call, proto) \
static notrace void \
perf_trace_##call(void *__data, proto);

#define _TRACE_PERF_INIT(call) \
.perf_event_enable = perf_trace_enable_##call, \
.perf_event_disable = perf_trace_disable_##call,
.perf_probe = perf_trace_##call,

#else
#define _TRACE_PERF_PROTO(call, proto)
#define _TRACE_PERF_INIT(call)
#endif /* CONFIG_PERF_EVENTS */

Expand Down Expand Up @@ -542,9 +490,9 @@ perf_trace_disable_##name(struct ftrace_event_call *unused) \
#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
\
static notrace void \
ftrace_raw_event_id_##call(struct ftrace_event_call *event_call, \
proto) \
ftrace_raw_event_##call(void *__data, proto) \
{ \
struct ftrace_event_call *event_call = __data; \
struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
struct ring_buffer_event *event; \
struct ftrace_raw_##call *entry; \
Expand Down Expand Up @@ -574,30 +522,23 @@ ftrace_raw_event_id_##call(struct ftrace_event_call *event_call, \
trace_nowake_buffer_unlock_commit(buffer, \
event, irq_flags, pc); \
}
/*
* The ftrace_test_probe is compiled out, it is only here as a build time check
* to make sure that if the tracepoint handling changes, the ftrace probe will
* fail to compile unless it too is updated.
*/

#undef DEFINE_EVENT
#define DEFINE_EVENT(template, call, proto, args) \
\
static notrace void ftrace_raw_event_##call(void *__ignore, proto) \
{ \
ftrace_raw_event_id_##template(&event_##call, args); \
} \
\
static notrace int \
ftrace_raw_reg_event_##call(struct ftrace_event_call *unused) \
{ \
return register_trace_##call(ftrace_raw_event_##call, NULL); \
} \
\
static notrace void \
ftrace_raw_unreg_event_##call(struct ftrace_event_call *unused) \
{ \
unregister_trace_##call(ftrace_raw_event_##call, NULL); \
} \
\
static struct trace_event ftrace_event_type_##call = { \
.trace = ftrace_raw_output_##call, \
};
}; \
\
static inline void ftrace_test_probe_##call(void) \
{ \
check_trace_callback_type_##call(ftrace_raw_event_##template); \
}

#undef DEFINE_EVENT_PRINT
#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
Expand All @@ -618,9 +559,12 @@ static struct trace_event ftrace_event_type_##call = { \

#undef DECLARE_EVENT_CLASS
#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
_TRACE_PERF_PROTO(call, PARAMS(proto)); \
static const char print_fmt_##call[] = print; \
static struct ftrace_event_class __used event_class_##call = { \
.system = __stringify(TRACE_SYSTEM) \
.system = __stringify(TRACE_SYSTEM), \
.probe = ftrace_raw_event_##call, \
_TRACE_PERF_INIT(call) \
};

#undef DEFINE_EVENT
Expand All @@ -633,11 +577,8 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
.class = &event_class_##template, \
.event = &ftrace_event_type_##call, \
.raw_init = trace_event_raw_init, \
.regfunc = ftrace_raw_reg_event_##call, \
.unregfunc = ftrace_raw_unreg_event_##call, \
.print_fmt = print_fmt_##template, \
.define_fields = ftrace_define_fields_##template, \
_TRACE_PERF_INIT(call) \
};

#undef DEFINE_EVENT_PRINT
Expand All @@ -652,11 +593,8 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
.class = &event_class_##template, \
.event = &ftrace_event_type_##call, \
.raw_init = trace_event_raw_init, \
.regfunc = ftrace_raw_reg_event_##call, \
.unregfunc = ftrace_raw_unreg_event_##call, \
.print_fmt = print_fmt_##call, \
.define_fields = ftrace_define_fields_##template, \
_TRACE_PERF_INIT(call) \
}

#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
Expand Down Expand Up @@ -756,9 +694,9 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
#undef DECLARE_EVENT_CLASS
#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
static notrace void \
perf_trace_templ_##call(struct ftrace_event_call *event_call, \
proto) \
perf_trace_##call(void *__data, proto) \
{ \
struct ftrace_event_call *event_call = __data; \
struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
struct ftrace_raw_##call *entry; \
u64 __addr = 0, __count = 1; \
Expand Down Expand Up @@ -791,15 +729,20 @@ perf_trace_templ_##call(struct ftrace_event_call *event_call, \
__count, irq_flags, __regs); \
}

/*
* This part is compiled out, it is only here as a build time check
* to make sure that if the tracepoint handling changes, the
* perf probe will fail to compile unless it too is updated.
*/
#undef DEFINE_EVENT
#define DEFINE_EVENT(template, call, proto, args) \
static notrace void perf_trace_##call(void *__ignore, proto) \
{ \
struct ftrace_event_call *event_call = &event_##call; \
\
perf_trace_templ_##template(event_call, args); \
#define DEFINE_EVENT(template, call, proto, args) \
static inline void perf_test_probe_##call(void) \
{ \
check_trace_callback_type_##call(perf_trace_##template); \
\
}


#undef DEFINE_EVENT_PRINT
#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args))
Expand Down
15 changes: 12 additions & 3 deletions kernel/trace/trace_event_perf.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -49,7 +49,12 @@ static int perf_trace_event_enable(struct ftrace_event_call *event)
rcu_assign_pointer(perf_trace_buf_nmi, buf);
}

ret = event->perf_event_enable(event);
if (event->class->reg)
ret = event->class->reg(event, TRACE_REG_PERF_REGISTER);
else
ret = tracepoint_probe_register(event->name,
event->class->perf_probe,
event);
if (!ret) {
total_ref_count++;
return 0;
Expand All @@ -75,7 +80,8 @@ int perf_trace_enable(int event_id)

mutex_lock(&event_mutex);
list_for_each_entry(event, &ftrace_events, list) {
if (event->id == event_id && event->perf_event_enable &&
if (event->id == event_id &&
event->class && event->class->perf_probe &&
try_module_get(event->mod)) {
ret = perf_trace_event_enable(event);
break;
Expand All @@ -93,7 +99,10 @@ static void perf_trace_event_disable(struct ftrace_event_call *event)
if (--event->perf_refcount > 0)
return;

event->perf_event_disable(event);
if (event->class->reg)
event->class->reg(event, TRACE_REG_PERF_UNREGISTER);
else
tracepoint_probe_unregister(event->name, event->class->perf_probe, event);

if (!--total_ref_count) {
buf = perf_trace_buf;
Expand Down
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