770cb24345
Impact: allow user apps to read binary format of basic ftrace entries
Currently, only defined raw events export their formats so a binary
reader can parse them. There's no reason that the default ftrace entries
can't export their formats.
This patch adds a subsystem called "ftrace" in the events directory
that includes the ftrace entries for basic ftrace recorded items.
These only have three files in the events directory:
type : printf
available_types : printf
format : format for the event entry
For example:
# cat /debug/tracing/events/ftrace/wakeup/format
name: wakeup
ID: 3
format:
field:unsigned char type; offset:0; size:1;
field:unsigned char flags; offset:1; size:1;
field:unsigned char preempt_count; offset:2; size:1;
field:int pid; offset:4; size:4;
field:int tgid; offset:8; size:4;
field:unsigned int prev_pid; offset:12; size:4;
field:unsigned char prev_prio; offset:16; size:1;
field:unsigned char prev_state; offset:17; size:1;
field:unsigned int next_pid; offset:20; size:4;
field:unsigned char next_prio; offset:24; size:1;
field:unsigned char next_state; offset:25; size:1;
field:unsigned int next_cpu; offset:28; size:4;
print fmt: "%u:%u:%u ==+ %u:%u:%u [%03u]"
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
82 lines
1.9 KiB
C
82 lines
1.9 KiB
C
/*
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* trace_export.c - export basic ftrace utilities to user space
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*
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* Copyright (C) 2009 Steven Rostedt <srostedt@redhat.com>
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*/
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#include <linux/stringify.h>
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#include <linux/kallsyms.h>
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#include <linux/seq_file.h>
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#include <linux/debugfs.h>
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include "trace_output.h"
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#include "trace_format.h"
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#undef TRACE_FIELD_ZERO_CHAR
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#define TRACE_FIELD_ZERO_CHAR(item) \
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ret = trace_seq_printf(s, "\tfield: char " #item ";\t" \
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"offset:%lu;\tsize:0;\n", \
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offsetof(typeof(field), item)); \
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if (!ret) \
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return 0;
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#undef TPRAWFMT
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#define TPRAWFMT(args...) args
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#undef TRACE_EVENT_FORMAT
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#define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt) \
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static int \
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ftrace_format_##call(struct trace_seq *s) \
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{ \
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struct args field; \
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int ret; \
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\
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tstruct; \
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\
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trace_seq_printf(s, "\nprint fmt: \"%s\"\n", tpfmt); \
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\
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return ret; \
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}
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#include "trace_event_types.h"
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#undef TRACE_ZERO_CHAR
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#define TRACE_ZERO_CHAR(arg)
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#undef TRACE_FIELD
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#define TRACE_FIELD(type, item, assign)\
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entry->item = assign;
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#undef TRACE_FIELD
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#define TRACE_FIELD(type, item, assign)\
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entry->item = assign;
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#undef TPCMD
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#define TPCMD(cmd...) cmd
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#undef TRACE_ENTRY
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#define TRACE_ENTRY entry
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#undef TRACE_FIELD_SPECIAL
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#define TRACE_FIELD_SPECIAL(type_item, item, cmd) \
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cmd;
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#undef TRACE_EVENT_FORMAT
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#define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt) \
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\
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static struct ftrace_event_call __used \
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__attribute__((__aligned__(4))) \
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__attribute__((section("_ftrace_events"))) event_##call = { \
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.name = #call, \
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.id = proto, \
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.system = __stringify(TRACE_SYSTEM), \
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.show_format = ftrace_format_##call, \
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}
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#include "trace_event_types.h"
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