tracing: add format files for ftrace default entries

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>

1 files changed, 81 insertions, 0 deletions

diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
new file mode 100644
index 000000000000..0fb7be73e31c
--- /dev/null
+++ b/kernel/trace/trace_export.c
@@ -0,0 +1,81 @@
+/*
+ * 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"
+
+#include "trace_format.h"
+
+#undef TRACE_FIELD_ZERO_CHAR
+#define TRACE_FIELD_ZERO_CHAR(item)                             \
+        ret = trace_seq_printf(s, "\tfield: char " #item ";\t"  \
+                               "offset:%lu;\tsize:0;\n",        \
+                               offsetof(typeof(field), item));  \
+        if (!ret)                                               \
+                return 0;
+
+
+#undef TPRAWFMT
+#define TPRAWFMT(args...) args
+
+#undef TRACE_EVENT_FORMAT
+#define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt)      \
+static int                                                              \
+ftrace_format_##call(struct trace_seq *s)                               \
+{                                                                       \
+        struct args field;                                              \
+        int ret;                                                        \
+                                                                        \
+        tstruct;                                                        \
+                                                                        \
+        trace_seq_printf(s, "\nprint fmt: \"%s\"\n", tpfmt);            \
+                                                                        \
+        return ret;                                                     \
+}
+
+#include "trace_event_types.h"
+
+#undef TRACE_ZERO_CHAR
+#define TRACE_ZERO_CHAR(arg)
+
+#undef TRACE_FIELD
+#define TRACE_FIELD(type, item, assign)\
+        entry->item = assign;
+
+#undef TRACE_FIELD
+#define TRACE_FIELD(type, item, assign)\
+        entry->item = assign;
+
+#undef TPCMD
+#define TPCMD(cmd...)   cmd
+
+#undef TRACE_ENTRY
+#define TRACE_ENTRY     entry
+
+#undef TRACE_FIELD_SPECIAL
+#define TRACE_FIELD_SPECIAL(type_item, item, cmd) \
+        cmd;
+
+#undef TRACE_EVENT_FORMAT
+#define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt)      \
+                                                                        \
+static struct ftrace_event_call __used                                  \
+__attribute__((__aligned__(4)))                                         \
+__attribute__((section("_ftrace_events"))) event_##call = {             \
+        .name                   = #call,                                \
+        .id                     = proto,                                \
+        .system                 = __stringify(TRACE_SYSTEM),            \
+        .show_format            = ftrace_format_##call,                 \
+}
+#include "trace_event_types.h"