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>
diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
new file mode 100644
index 0000000..0fb7be7
--- /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"
