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Diffstat (limited to 'include/linux/tracepoint.h')
| -rw-r--r-- | include/linux/tracepoint.h | 381 |
1 files changed, 381 insertions, 0 deletions
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h new file mode 100644 index 00000000..d530a446 --- /dev/null +++ b/include/linux/tracepoint.h @@ -0,0 +1,381 @@ +#ifndef _LINUX_TRACEPOINT_H +#define _LINUX_TRACEPOINT_H + +/* + * Kernel Tracepoint API. + * + * See Documentation/trace/tracepoints.txt. + * + * (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> + * + * Heavily inspired from the Linux Kernel Markers. + * + * This file is released under the GPLv2. + * See the file COPYING for more details. + */ + +#include <linux/errno.h> +#include <linux/types.h> +#include <linux/rcupdate.h> +#include <linux/jump_label.h> + +struct module; +struct tracepoint; + +struct tracepoint_func { + void *func; + void *data; +}; + +struct tracepoint { + const char *name; /* Tracepoint name */ + struct jump_label_key key; + void (*regfunc)(void); + void (*unregfunc)(void); + struct tracepoint_func __rcu *funcs; +}; + +/* + * Connect a probe to a tracepoint. + * Internal API, should not be used directly. + */ +extern int tracepoint_probe_register(const char *name, void *probe, void *data); + +/* + * Disconnect a probe from a tracepoint. + * Internal API, should not be used directly. + */ +extern int +tracepoint_probe_unregister(const char *name, void *probe, void *data); + +extern int tracepoint_probe_register_noupdate(const char *name, void *probe, + void *data); +extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe, + void *data); +extern void tracepoint_probe_update_all(void); + +struct tracepoint_iter { + struct module *module; + struct tracepoint * const *tracepoint; +}; + +extern void tracepoint_iter_start(struct tracepoint_iter *iter); +extern void tracepoint_iter_next(struct tracepoint_iter *iter); +extern void tracepoint_iter_stop(struct tracepoint_iter *iter); +extern void tracepoint_iter_reset(struct tracepoint_iter *iter); +extern int tracepoint_get_iter_range(struct tracepoint * const **tracepoint, + struct tracepoint * const *begin, struct tracepoint * const *end); + +/* + * tracepoint_synchronize_unregister must be called between the last tracepoint + * probe unregistration and the end of module exit to make sure there is no + * caller executing a probe when it is freed. + */ +static inline void tracepoint_synchronize_unregister(void) +{ + synchronize_sched(); +} + +#define PARAMS(args...) args + +#ifdef CONFIG_TRACEPOINTS +extern +void tracepoint_update_probe_range(struct tracepoint * const *begin, + struct tracepoint * const *end); +#else +static inline +void tracepoint_update_probe_range(struct tracepoint * const *begin, + struct tracepoint * const *end) +{ } +#endif /* CONFIG_TRACEPOINTS */ + +#endif /* _LINUX_TRACEPOINT_H */ + +/* + * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include + * file ifdef protection. + * This is due to the way trace events work. If a file includes two + * trace event headers under one "CREATE_TRACE_POINTS" the first include + * will override the TRACE_EVENT and break the second include. + */ + +#ifndef DECLARE_TRACE + +#define TP_PROTO(args...) args +#define TP_ARGS(args...) args +#define TP_CONDITION(args...) args + +#ifdef CONFIG_TRACEPOINTS + +/* + * it_func[0] is never NULL because there is at least one element in the array + * when the array itself is non NULL. + * + * Note, the proto and args passed in includes "__data" as the first parameter. + * The reason for this is to handle the "void" prototype. If a tracepoint + * has a "void" prototype, then it is invalid to declare a function + * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just + * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto". + */ +#define __DO_TRACE(tp, proto, args, cond) \ + do { \ + struct tracepoint_func *it_func_ptr; \ + void *it_func; \ + void *__data; \ + \ + if (!(cond)) \ + return; \ + 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(); \ + } while (0) + +/* + * Make sure the alignment of the structure in the __tracepoints section will + * not add unwanted padding between the beginning of the section and the + * structure. Force alignment to the same alignment as the section start. + */ +#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ + extern struct tracepoint __tracepoint_##name; \ + static inline void trace_##name(proto) \ + { \ + if (static_branch(&__tracepoint_##name.key)) \ + __DO_TRACE(&__tracepoint_##name, \ + TP_PROTO(data_proto), \ + TP_ARGS(data_args), \ + TP_CONDITION(cond)); \ + } \ + static inline int \ + register_trace_##name(void (*probe)(data_proto), void *data) \ + { \ + return tracepoint_probe_register(#name, (void *)probe, \ + data); \ + } \ + static inline int \ + unregister_trace_##name(void (*probe)(data_proto), void *data) \ + { \ + return tracepoint_probe_unregister(#name, (void *)probe, \ + data); \ + } \ + static inline void \ + check_trace_callback_type_##name(void (*cb)(data_proto)) \ + { \ + } + +/* + * We have no guarantee that gcc and the linker won't up-align the tracepoint + * structures, so we create an array of pointers that will be used for iteration + * on the tracepoints. + */ +#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, JUMP_LABEL_INIT, 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 EXPORT_TRACEPOINT_SYMBOL_GPL(name) \ + EXPORT_SYMBOL_GPL(__tracepoint_##name) +#define EXPORT_TRACEPOINT_SYMBOL(name) \ + EXPORT_SYMBOL(__tracepoint_##name) + +#else /* !CONFIG_TRACEPOINTS */ +#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ + static inline void trace_##name(proto) \ + { } \ + static inline int \ + register_trace_##name(void (*probe)(data_proto), \ + void *data) \ + { \ + return -ENOSYS; \ + } \ + static inline int \ + unregister_trace_##name(void (*probe)(data_proto), \ + void *data) \ + { \ + return -ENOSYS; \ + } \ + static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \ + { \ + } + +#define DEFINE_TRACE_FN(name, reg, unreg) +#define DEFINE_TRACE(name) +#define EXPORT_TRACEPOINT_SYMBOL_GPL(name) +#define EXPORT_TRACEPOINT_SYMBOL(name) + +#endif /* CONFIG_TRACEPOINTS */ + +/* + * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype + * (void). "void" is a special value in a function prototype and can + * not be combined with other arguments. Since the DECLARE_TRACE() + * macro adds a data element at the beginning of the prototype, + * we need a way to differentiate "(void *data, proto)" from + * "(void *data, void)". The second prototype is invalid. + * + * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype + * and "void *__data" as the callback prototype. + * + * DECLARE_TRACE() passes "proto" as the tracepoint protoype and + * "void *__data, proto" as the callback prototype. + */ +#define DECLARE_TRACE_NOARGS(name) \ + __DECLARE_TRACE(name, void, , 1, void *__data, __data) + +#define DECLARE_TRACE(name, proto, args) \ + __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1, \ + PARAMS(void *__data, proto), \ + PARAMS(__data, args)) + +#define DECLARE_TRACE_CONDITION(name, proto, args, cond) \ + __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \ + PARAMS(void *__data, proto), \ + PARAMS(__data, args)) + +#define TRACE_EVENT_FLAGS(event, flag) + +#endif /* DECLARE_TRACE */ + +#ifndef TRACE_EVENT +/* + * For use with the TRACE_EVENT macro: + * + * We define a tracepoint, its arguments, its printk format + * and its 'fast binay 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. + */ + +#define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print) +#define DEFINE_EVENT(template, name, proto, args) \ + DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) +#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \ + DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) +#define DEFINE_EVENT_CONDITION(template, name, proto, \ + args, cond) \ + DECLARE_TRACE_CONDITION(name, PARAMS(proto), \ + PARAMS(args), PARAMS(cond)) + +#define TRACE_EVENT(name, proto, args, struct, assign, print) \ + DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) +#define TRACE_EVENT_FN(name, proto, args, struct, \ + assign, print, reg, unreg) \ + DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) +#define TRACE_EVENT_CONDITION(name, proto, args, cond, \ + struct, assign, print) \ + DECLARE_TRACE_CONDITION(name, PARAMS(proto), \ + PARAMS(args), PARAMS(cond)) + +#define TRACE_EVENT_FLAGS(event, flag) + +#endif /* ifdef TRACE_EVENT (see note above) */ |