Files
linux/kernel/trace/trace_export.c
Vaibhav Nagarnaik c0316f975b tracing: Fix array size mismatch in format string
commit 87291347c4 upstream.

In event format strings, the array size is reported in two locations.
One in array subscript and then via the "size:" attribute. The values
reported there have a mismatch.

For e.g., in sched:sched_switch the prev_comm and next_comm character
arrays have subscript values as [32] where as the actual field size is
16.

name: sched_switch
ID: 301
format:
        field:unsigned short common_type;       offset:0;       size:2; signed:0;
        field:unsigned char common_flags;       offset:2;       size:1; signed:0;
        field:unsigned char common_preempt_count;       offset:3;       size:1;signed:0;
        field:int common_pid;   offset:4;       size:4; signed:1;

        field:char prev_comm[32];       offset:8;       size:16;        signed:1;
        field:pid_t prev_pid;   offset:24;      size:4; signed:1;
        field:int prev_prio;    offset:28;      size:4; signed:1;
        field:long prev_state;  offset:32;      size:8; signed:1;
        field:char next_comm[32];       offset:40;      size:16;        signed:1;
        field:pid_t next_pid;   offset:56;      size:4; signed:1;
        field:int next_prio;    offset:60;      size:4; signed:1;

After bisection, the following commit was blamed:
92edca0 tracing: Use direct field, type and system names

This commit removes the duplication of strings for field->name and
field->type assuming that all the strings passed in
__trace_define_field() are immutable. This is not true for arrays, where
the type string is created in event_storage variable and field->type for
all array fields points to event_storage.

Use __stringify() to create a string constant for the type string.

Also, get rid of event_storage and event_storage_mutex that are not
needed anymore.

also, an added benefit is that this reduces the overhead of events a bit more:

   text    data     bss     dec     hex filename
8424787 2036472 1302528 11763787         b3804b vmlinux
8420814 2036408 1302528 11759750         b37086 vmlinux.patched

Link: http://lkml.kernel.org/r/1392349908-29685-1-git-send-email-vnagarnaik@google.com

Cc: Laurent Chavey <chavey@google.com>
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2014-03-31 14:22:25 +02:00

196 lines
5.2 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
/*
* 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 ftrace_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 ftrace_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 ftrace_event_call __used event_##call = { \
.name = #call, \
.event.type = etype, \
.class = &event_class_ftrace_##call, \
.print_fmt = print, \
.flags = TRACE_EVENT_FL_IGNORE_ENABLE, \
}; \
struct ftrace_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)
int ftrace_event_is_function(struct ftrace_event_call *call)
{
return call == &event_function;
}
#include "trace_entries.h"