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linux-next/kernel/trace/trace_export.c
Steven Rostedt 0429578016 tracing/events: Show real number in array fields
Currently we have in something like the sched_switch event:

  field:char prev_comm[TASK_COMM_LEN];	offset:12;	size:16;	signed:1;

When a userspace tool such as perf tries to parse this, the
TASK_COMM_LEN is meaningless. This is done because the TRACE_EVENT() macro
simply uses a #len to show the string of the length. When the length is
an enum, we get a string that means nothing for tools.

By adding a static buffer and a mutex to protect it, we can store the
string into that buffer with snprintf and show the actual number.
Now we get:

  field:char prev_comm[16];       offset:12;      size:16;        signed:1;

Something much more useful.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2010-11-19 10:18:47 -05:00

174 lines
4.5 KiB
C

/*
* 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/debugfs.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include "trace_output.h"
#undef TRACE_SYSTEM
#define TRACE_SYSTEM ftrace
/* 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) \
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) \
FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print))
#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_OTHER); \
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_OTHER); \
if (ret) \
return ret;
#undef __array
#define __array(type, item, len) \
do { \
BUILD_BUG_ON(len > MAX_FILTER_STR_VAL); \
mutex_lock(&event_storage_mutex); \
snprintf(event_storage, sizeof(event_storage), \
"%s[%d]", #type, len); \
ret = trace_define_field(event_call, event_storage, #item, \
offsetof(typeof(field), item), \
sizeof(field.item), \
is_signed_type(type), FILTER_OTHER); \
mutex_unlock(&event_storage_mutex); \
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_OTHER); \
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_OTHER);\
if (ret) \
return ret;
#undef FTRACE_ENTRY
#define FTRACE_ENTRY(name, struct_name, id, tstruct, print) \
int \
ftrace_define_fields_##name(struct ftrace_event_call *event_call) \
{ \
struct struct_name field; \
int ret; \
\
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...) #fmt ", " __stringify(args)
#undef FTRACE_ENTRY
#define FTRACE_ENTRY(call, struct_name, etype, tstruct, print) \
\
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),\
}; \
\
struct ftrace_event_call __used \
__attribute__((__aligned__(4))) \
__attribute__((section("_ftrace_events"))) event_##call = { \
.name = #call, \
.event.type = etype, \
.class = &event_class_ftrace_##call, \
.print_fmt = print, \
}; \
#include "trace_entries.h"