ftrace macro
2016-03-19 13:43
369 查看
* Usage
Two elements are required for tracepoints :
- A tracepoint definition, placed in a header file.
- The tracepoint statement, in C code.
数据结构和宏定义在文件
include/linux/tacepoint.h
struct tracepoint_func {
void *func;
void *data;
};
struct tracepoint {
const char *name;
/* Tracepoint name */
struct static_key key;
void (*regfunc)(void);
void (*unregfunc)(void);
struct tracepoint_func __rcu *funcs;
};
extern int
tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
extern int
tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
在头文件中包含tracepoint.h, 并调用DECLARE_TRACE定义一组函数
#define TP_PROTO(args...) args
#define TP_ARGS(args...) args
#define TP_CONDITION(args...) args
#define DECLARE_TRACE(name, proto, args) \
__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1,
\
PARAMS(void *__data, proto),
\
PARAMS(__data, args))
#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
extern struct tracepoint __tracepoint_##name;
\
static inline void trace_##name(proto)
\
{ \
if (static_key_false(&__tracepoint_##name.key))
\
__DO_TRACE(&__tracepoint_##name,
\
TP_PROTO(data_proto),
\
TP_ARGS(data_args),
\
TP_CONDITION(cond),,);
\
if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {
\
rcu_read_lock_sched_notrace();
\
rcu_dereference_sched(__tracepoint_##name.funcs);\
rcu_read_unlock_sched_notrace();
\
} \
} \
__DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args),
\
PARAMS(cond), PARAMS(data_proto), PARAMS(data_args))
\
static inline int
\
register_trace_##name(void (*probe)(data_proto), void *data)
\
{ \
return tracepoint_probe_register(&__tracepoint_##name,
\
(void *)probe, data);
\
} \
static inline int
\
unregister_trace_##name(void (*probe)(data_proto), void *data)
\
{ \
return tracepoint_probe_unregister(&__tracepoint_##name,\
(void *)probe, data);
\
} \
static inline void
\
check_trace_callback_type_##name(void (*cb)(data_proto))
\
{ \
} \
static inline bool
\
trace_##name##_enabled(void)
\
{ \
return static_key_false(&__tracepoint_##name.key);
\
}
DEFINE_TRACE:
#define DEFINE_TRACE_FN(name, reg, unreg) \
static const char __tpstrtab_##name[]
\
__attribute__((section("__tracepoints_strings"))) = #name;
\
struct tracepoint __tracepoint_##name
\
__attribute__((section("__tracepoints"))) =
\
{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
static struct tracepoint * const __tracepoint_ptr_##name __used
\
__attribute__((section("__tracepoints_ptrs"))) =
\
&__tracepoint_##name;
#define DEFINE_TRACE(name) \
DEFINE_TRACE_FN(name, NULL, NULL);
#define __DO_TRACE(tp, proto, args, cond, prercu, postrcu)
\
do { \
struct tracepoint_func *it_func_ptr;
\
void *it_func;
\
void *__data;
\
\
if (!(cond))
\
return;
\
prercu;
\
rcu_read_lock_sched_notrace();
\
it_func_ptr = rcu_dereference_sched((tp)->funcs);
\
if (it_func_ptr) {
\
do { \
it_func = (it_func_ptr)->func;
\
__data = (it_func_ptr)->data;
\
((void(*)(proto))(it_func))(args);
\
} while ((++it_func_ptr)->func);
\
} \
rcu_read_unlock_sched_notrace();
\
postrcu;
\
} while (0)
static inline void trace_##name(proto) \
{ \
if (static_key_false(&__tracepoint_##name.key))
\
__DO_TRACE(&__tracepoint_##name,
\
TP_PROTO(data_proto),
\
TP_ARGS(data_args),
\
TP_CONDITION(cond),,);
\
if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {
\
rcu_read_lock_sched_notrace();
\
rcu_dereference_sched(__tracepoint_##name.funcs);\
rcu_read_unlock_sched_notrace();
\
} \
}
在文件 trace/trace_sched_switch.c文件中看到了register, 而文件sample中没有看到
TRACE_EVENT是DECLARE_TRACE的变种:
#define TRACE_EVENT(name, proto, args, struct, assign, print)
\
DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
/*
* For use with the TRACE_EVENT macro:
*
* We define a tracepoint, its arguments, its printk format
* and its 'fast binary record' layout.
*
* Firstly, name your tracepoint via TRACE_EVENT(name : the
* 'subsystem_event' notation is fine.
*
* Think about this whole construct as the
* 'trace_sched_switch() function' from now on.
*
*
* TRACE_EVENT(sched_switch,
*
* *
* * A function has a regular function arguments
* * prototype, declare it via TP_PROTO():
* *
*
* TP_PROTO(struct rq *rq, struct task_struct *prev,
* struct task_struct *next),
*
* *
* * Define the call signature of the 'function'.
* * (Design sidenote: we use this instead of a
* * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
* *
*
* TP_ARGS(rq, prev, next),
*
* *
* * Fast binary tracing: define the trace record via
* * TP_STRUCT__entry(). You can think about it like a
* * regular C structure local variable definition.
* *
* * This is how the trace record is structured and will
* * be saved into the ring buffer. These are the fields
* * that will be exposed to user-space in
* * /sys/kernel/debug/tracing/events/<*>/format.
* *
* * The declared 'local variable' is called '__entry'
* *
* * __field(pid_t, prev_prid) is equivalent to a standard declariton:
* *
* * pid_t
prev_pid;
* *
* * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
* *
* * char
prev_comm[TASK_COMM_LEN];
* *
*
* TP_STRUCT__entry(
* __array(
char, prev_comm,
TASK_COMM_LEN )
* __field(
pid_t, prev_pid
)
* __field(
int, prev_prio
)
* __array(
char, next_comm,
TASK_COMM_LEN )
* __field(
pid_t, next_pid
)
* __field(
int, next_prio
)
* ),
*
* *
* * Assign the entry into the trace record, by embedding
* * a full C statement block into TP_fast_assign(). You
* * can refer to the trace record as '__entry' -
* * otherwise you can put arbitrary C code in here.
* *
* * Note: this C code will execute every time a trace event
* * happens, on an active tracepoint.
* *
*
* TP_fast_assign(
* memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
* __entry->prev_pid
= prev->pid;
* __entry->prev_prio
= prev->prio;
* memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
* __entry->next_pid
= next->pid;
* __entry->next_prio
= next->prio;
* ),
*
* *
* * Formatted output of a trace record via TP_printk().
* * This is how the tracepoint will appear under ftrace
* * plugins that make use of this tracepoint.
* *
* * (raw-binary tracing wont actually perform this step.)
* *
*
* TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
* __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
* __entry->next_comm, __entry->next_pid, __entry->next_prio),
*
* );
*
* This macro construct is thus used for the regular printk format
* tracing setup, it is used to construct a function pointer based
* tracepoint callback (this is used by programmatic plugins and
* can also by used by generic instrumentation like SystemTap), and
* it is also used to expose a structured trace record in
* /sys/kernel/debug/tracing/events/.
*
* A set of (un)registration functions can be passed to the variant
* TRACE_EVENT_FN to perform any (un)registration work.
*/
这里TP_printk的意思是:
#define TP_printk(fmt, args...) fmt "\n", args
Two elements are required for tracepoints :
- A tracepoint definition, placed in a header file.
- The tracepoint statement, in C code.
数据结构和宏定义在文件
include/linux/tacepoint.h
struct tracepoint_func {
void *func;
void *data;
};
struct tracepoint {
const char *name;
/* Tracepoint name */
struct static_key key;
void (*regfunc)(void);
void (*unregfunc)(void);
struct tracepoint_func __rcu *funcs;
};
extern int
tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
extern int
tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
在头文件中包含tracepoint.h, 并调用DECLARE_TRACE定义一组函数
#define TP_PROTO(args...) args
#define TP_ARGS(args...) args
#define TP_CONDITION(args...) args
#define DECLARE_TRACE(name, proto, args) \
__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1,
\
PARAMS(void *__data, proto),
\
PARAMS(__data, args))
#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
extern struct tracepoint __tracepoint_##name;
\
static inline void trace_##name(proto)
\
{ \
if (static_key_false(&__tracepoint_##name.key))
\
__DO_TRACE(&__tracepoint_##name,
\
TP_PROTO(data_proto),
\
TP_ARGS(data_args),
\
TP_CONDITION(cond),,);
\
if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {
\
rcu_read_lock_sched_notrace();
\
rcu_dereference_sched(__tracepoint_##name.funcs);\
rcu_read_unlock_sched_notrace();
\
} \
} \
__DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args),
\
PARAMS(cond), PARAMS(data_proto), PARAMS(data_args))
\
static inline int
\
register_trace_##name(void (*probe)(data_proto), void *data)
\
{ \
return tracepoint_probe_register(&__tracepoint_##name,
\
(void *)probe, data);
\
} \
static inline int
\
unregister_trace_##name(void (*probe)(data_proto), void *data)
\
{ \
return tracepoint_probe_unregister(&__tracepoint_##name,\
(void *)probe, data);
\
} \
static inline void
\
check_trace_callback_type_##name(void (*cb)(data_proto))
\
{ \
} \
static inline bool
\
trace_##name##_enabled(void)
\
{ \
return static_key_false(&__tracepoint_##name.key);
\
}
DEFINE_TRACE:
#define DEFINE_TRACE_FN(name, reg, unreg) \
static const char __tpstrtab_##name[]
\
__attribute__((section("__tracepoints_strings"))) = #name;
\
struct tracepoint __tracepoint_##name
\
__attribute__((section("__tracepoints"))) =
\
{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
static struct tracepoint * const __tracepoint_ptr_##name __used
\
__attribute__((section("__tracepoints_ptrs"))) =
\
&__tracepoint_##name;
#define DEFINE_TRACE(name) \
DEFINE_TRACE_FN(name, NULL, NULL);
#define __DO_TRACE(tp, proto, args, cond, prercu, postrcu)
\
do { \
struct tracepoint_func *it_func_ptr;
\
void *it_func;
\
void *__data;
\
\
if (!(cond))
\
return;
\
prercu;
\
rcu_read_lock_sched_notrace();
\
it_func_ptr = rcu_dereference_sched((tp)->funcs);
\
if (it_func_ptr) {
\
do { \
it_func = (it_func_ptr)->func;
\
__data = (it_func_ptr)->data;
\
((void(*)(proto))(it_func))(args);
\
} while ((++it_func_ptr)->func);
\
} \
rcu_read_unlock_sched_notrace();
\
postrcu;
\
} while (0)
static inline void trace_##name(proto) \
{ \
if (static_key_false(&__tracepoint_##name.key))
\
__DO_TRACE(&__tracepoint_##name,
\
TP_PROTO(data_proto),
\
TP_ARGS(data_args),
\
TP_CONDITION(cond),,);
\
if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {
\
rcu_read_lock_sched_notrace();
\
rcu_dereference_sched(__tracepoint_##name.funcs);\
rcu_read_unlock_sched_notrace();
\
} \
}
在文件 trace/trace_sched_switch.c文件中看到了register, 而文件sample中没有看到
TRACE_EVENT是DECLARE_TRACE的变种:
#define TRACE_EVENT(name, proto, args, struct, assign, print)
\
DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
/*
* For use with the TRACE_EVENT macro:
*
* We define a tracepoint, its arguments, its printk format
* and its 'fast binary record' layout.
*
* Firstly, name your tracepoint via TRACE_EVENT(name : the
* 'subsystem_event' notation is fine.
*
* Think about this whole construct as the
* 'trace_sched_switch() function' from now on.
*
*
* TRACE_EVENT(sched_switch,
*
* *
* * A function has a regular function arguments
* * prototype, declare it via TP_PROTO():
* *
*
* TP_PROTO(struct rq *rq, struct task_struct *prev,
* struct task_struct *next),
*
* *
* * Define the call signature of the 'function'.
* * (Design sidenote: we use this instead of a
* * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
* *
*
* TP_ARGS(rq, prev, next),
*
* *
* * Fast binary tracing: define the trace record via
* * TP_STRUCT__entry(). You can think about it like a
* * regular C structure local variable definition.
* *
* * This is how the trace record is structured and will
* * be saved into the ring buffer. These are the fields
* * that will be exposed to user-space in
* * /sys/kernel/debug/tracing/events/<*>/format.
* *
* * The declared 'local variable' is called '__entry'
* *
* * __field(pid_t, prev_prid) is equivalent to a standard declariton:
* *
* * pid_t
prev_pid;
* *
* * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
* *
* * char
prev_comm[TASK_COMM_LEN];
* *
*
* TP_STRUCT__entry(
* __array(
char, prev_comm,
TASK_COMM_LEN )
* __field(
pid_t, prev_pid
)
* __field(
int, prev_prio
)
* __array(
char, next_comm,
TASK_COMM_LEN )
* __field(
pid_t, next_pid
)
* __field(
int, next_prio
)
* ),
*
* *
* * Assign the entry into the trace record, by embedding
* * a full C statement block into TP_fast_assign(). You
* * can refer to the trace record as '__entry' -
* * otherwise you can put arbitrary C code in here.
* *
* * Note: this C code will execute every time a trace event
* * happens, on an active tracepoint.
* *
*
* TP_fast_assign(
* memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
* __entry->prev_pid
= prev->pid;
* __entry->prev_prio
= prev->prio;
* memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
* __entry->next_pid
= next->pid;
* __entry->next_prio
= next->prio;
* ),
*
* *
* * Formatted output of a trace record via TP_printk().
* * This is how the tracepoint will appear under ftrace
* * plugins that make use of this tracepoint.
* *
* * (raw-binary tracing wont actually perform this step.)
* *
*
* TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
* __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
* __entry->next_comm, __entry->next_pid, __entry->next_prio),
*
* );
*
* This macro construct is thus used for the regular printk format
* tracing setup, it is used to construct a function pointer based
* tracepoint callback (this is used by programmatic plugins and
* can also by used by generic instrumentation like SystemTap), and
* it is also used to expose a structured trace record in
* /sys/kernel/debug/tracing/events/.
*
* A set of (un)registration functions can be passed to the variant
* TRACE_EVENT_FN to perform any (un)registration work.
*/
这里TP_printk的意思是:
#define TP_printk(fmt, args...) fmt "\n", args
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