linux/kernel/trace/trace_export.c
Steven Rostedt (VMware) 3dd8095368 tracing: Add trigger file for trace_markers tracefs/ftrace/print
Allow writing to the trace_markers file initiate triggers defined in
tracefs/ftrace/print/trigger file. This will allow of user space to trigger
the same type of triggers (including histograms) that the trace events use.

Had to create a ftrace_event_register() function that will become the
trace_marker print event's reg() function. This is required because of how
triggers are enabled:

  event_trigger_write() {
    event_trigger_regex_write() {
      trigger_process_regex() {
        for p in trigger_commands {
          p->func(); /* trigger_snapshot_cmd->func */
            event_trigger_callback() {
              cmd_ops->reg() /* register_trigger() */ {
                trace_event_trigger_enable_disable() {
                  trace_event_enable_disable() {
                    call->class->reg();

Without the reg() function, the trigger code will call a NULL pointer and
crash the system.

Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Karim Yaghmour <karim.yaghmour@opersys.com>
Cc: Brendan Gregg <bgregg@netflix.com>
Suggested-by: Joel Fernandes <joelaf@google.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-05-29 08:28:53 -04:00

204 lines
5.3 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* trace_export.c - export basic ftrace utilities to user space
*
* Copyright (C) 2009 Steven Rostedt <srostedt@redhat.com>
*/
#include <linux/stringify.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/init.h>
#include "trace_output.h"
/* Stub function for events with triggers */
static int ftrace_event_register(struct trace_event_call *call,
enum trace_reg type, void *data)
{
return 0;
}
#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, \
filter, regfn) \
FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print), \
filter)
/* not needed for this file */
#undef __field_struct
#define __field_struct(type, item)
#undef __field
#define __field(type, item) type item;
#undef __field_desc
#define __field_desc(type, container, item) type item;
#undef __array
#define __array(type, item, size) type item[size];
#undef __array_desc
#define __array_desc(type, container, item, size) type item[size];
#undef __dynamic_array
#define __dynamic_array(type, item) type item[];
#undef F_STRUCT
#define F_STRUCT(args...) args
#undef F_printk
#define F_printk(fmt, args...) fmt, args
#undef FTRACE_ENTRY
#define FTRACE_ENTRY(name, struct_name, id, tstruct, print, filter) \
struct ____ftrace_##name { \
tstruct \
}; \
static void __always_unused ____ftrace_check_##name(void) \
{ \
struct ____ftrace_##name *__entry = NULL; \
\
/* force compile-time check on F_printk() */ \
printk(print); \
}
#undef FTRACE_ENTRY_DUP
#define FTRACE_ENTRY_DUP(name, struct_name, id, tstruct, print, filter) \
FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print), \
filter)
#include "trace_entries.h"
#undef __field
#define __field(type, item) \
ret = trace_define_field(event_call, #type, #item, \
offsetof(typeof(field), item), \
sizeof(field.item), \
is_signed_type(type), filter_type); \
if (ret) \
return ret;
#undef __field_desc
#define __field_desc(type, container, item) \
ret = trace_define_field(event_call, #type, #item, \
offsetof(typeof(field), \
container.item), \
sizeof(field.container.item), \
is_signed_type(type), filter_type); \
if (ret) \
return ret;
#undef __array
#define __array(type, item, len) \
do { \
char *type_str = #type"["__stringify(len)"]"; \
BUILD_BUG_ON(len > MAX_FILTER_STR_VAL); \
ret = trace_define_field(event_call, type_str, #item, \
offsetof(typeof(field), item), \
sizeof(field.item), \
is_signed_type(type), filter_type); \
if (ret) \
return ret; \
} while (0);
#undef __array_desc
#define __array_desc(type, container, item, len) \
BUILD_BUG_ON(len > MAX_FILTER_STR_VAL); \
ret = trace_define_field(event_call, #type "[" #len "]", #item, \
offsetof(typeof(field), \
container.item), \
sizeof(field.container.item), \
is_signed_type(type), filter_type); \
if (ret) \
return ret;
#undef __dynamic_array
#define __dynamic_array(type, item) \
ret = trace_define_field(event_call, #type "[]", #item, \
offsetof(typeof(field), item), \
0, is_signed_type(type), filter_type);\
if (ret) \
return ret;
#undef FTRACE_ENTRY
#define FTRACE_ENTRY(name, struct_name, id, tstruct, print, filter) \
static int __init \
ftrace_define_fields_##name(struct trace_event_call *event_call) \
{ \
struct struct_name field; \
int ret; \
int filter_type = filter; \
\
tstruct; \
\
return ret; \
}
#include "trace_entries.h"
#undef __entry
#define __entry REC
#undef __field
#define __field(type, item)
#undef __field_desc
#define __field_desc(type, container, item)
#undef __array
#define __array(type, item, len)
#undef __array_desc
#define __array_desc(type, container, item, len)
#undef __dynamic_array
#define __dynamic_array(type, item)
#undef F_printk
#define F_printk(fmt, args...) __stringify(fmt) ", " __stringify(args)
#undef FTRACE_ENTRY_REG
#define FTRACE_ENTRY_REG(call, struct_name, etype, tstruct, print, filter,\
regfn) \
\
struct trace_event_class __refdata 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 trace_event_call __used event_##call = { \
.class = &event_class_ftrace_##call, \
{ \
.name = #call, \
}, \
.event.type = etype, \
.print_fmt = print, \
.flags = TRACE_EVENT_FL_IGNORE_ENABLE, \
}; \
struct trace_event_call __used \
__attribute__((section("_ftrace_events"))) *__event_##call = &event_##call;
#undef FTRACE_ENTRY
#define FTRACE_ENTRY(call, struct_name, etype, tstruct, print, filter) \
FTRACE_ENTRY_REG(call, struct_name, etype, \
PARAMS(tstruct), PARAMS(print), filter, NULL)
bool ftrace_event_is_function(struct trace_event_call *call)
{
return call == &event_function;
}
#include "trace_entries.h"