2 * (C) Copyright 2009-2011 -
3 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
5 * LTTng function tracer integration module.
7 * Dual LGPL v2.1/GPL v2 license.
11 * Ftrace function tracer does not seem to provide synchronization between probe
12 * teardown and callback execution. Therefore, we make this module permanently
13 * loaded (unloadable).
15 * TODO: Move to register_ftrace_function() (which is exported for
16 * modules) for Linux >= 3.0. It is faster (only enables the selected
17 * functions), and will stay there.
20 #include <linux/module.h>
21 #include <linux/ftrace.h>
22 #include <linux/slab.h>
23 #include "../ltt-events.h"
24 #include "../wrapper/ringbuffer/frontend_types.h"
25 #include "../wrapper/ftrace.h"
26 #include "../wrapper/vmalloc.h"
27 #include "../ltt-tracer.h"
30 void lttng_ftrace_handler(unsigned long ip
, unsigned long parent_ip
, void **data
)
32 struct ltt_event
*event
= *data
;
33 struct ltt_channel
*chan
= event
->chan
;
34 struct lib_ring_buffer_ctx ctx
;
37 unsigned long parent_ip
;
41 if (!ACCESS_ONCE(chan
->session
->active
))
43 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, event
,
44 sizeof(payload
), ltt_alignof(payload
), -1);
45 ret
= chan
->ops
->event_reserve(&ctx
, event
->id
);
49 payload
.parent_ip
= parent_ip
;
50 lib_ring_buffer_align_ctx(&ctx
, ltt_alignof(payload
));
51 chan
->ops
->event_write(&ctx
, &payload
, sizeof(payload
));
52 chan
->ops
->event_commit(&ctx
);
57 * Create event description
60 int lttng_create_ftrace_event(const char *name
, struct ltt_event
*event
)
62 struct lttng_event_field
*fields
;
63 struct lttng_event_desc
*desc
;
66 desc
= kzalloc(sizeof(*event
->desc
), GFP_KERNEL
);
69 desc
->name
= kstrdup(name
, GFP_KERNEL
);
75 desc
->fields
= fields
=
76 kzalloc(2 * sizeof(struct lttng_event_field
), GFP_KERNEL
);
81 fields
[0].name
= "ip";
82 fields
[0].type
.atype
= atype_integer
;
83 fields
[0].type
.u
.basic
.integer
.size
= sizeof(unsigned long) * CHAR_BIT
;
84 fields
[0].type
.u
.basic
.integer
.alignment
= ltt_alignof(unsigned long) * CHAR_BIT
;
85 fields
[0].type
.u
.basic
.integer
.signedness
= is_signed_type(unsigned long);
86 fields
[0].type
.u
.basic
.integer
.reverse_byte_order
= 0;
87 fields
[0].type
.u
.basic
.integer
.base
= 16;
88 fields
[0].type
.u
.basic
.integer
.encoding
= lttng_encode_none
;
90 fields
[1].name
= "parent_ip";
91 fields
[1].type
.atype
= atype_integer
;
92 fields
[1].type
.u
.basic
.integer
.size
= sizeof(unsigned long) * CHAR_BIT
;
93 fields
[1].type
.u
.basic
.integer
.alignment
= ltt_alignof(unsigned long) * CHAR_BIT
;
94 fields
[1].type
.u
.basic
.integer
.signedness
= is_signed_type(unsigned long);
95 fields
[1].type
.u
.basic
.integer
.reverse_byte_order
= 0;
96 fields
[1].type
.u
.basic
.integer
.base
= 16;
97 fields
[1].type
.u
.basic
.integer
.encoding
= lttng_encode_none
;
99 desc
->owner
= THIS_MODULE
;
112 struct ftrace_probe_ops lttng_ftrace_ops
= {
113 .func
= lttng_ftrace_handler
,
116 int lttng_ftrace_register(const char *name
,
117 const char *symbol_name
,
118 struct ltt_event
*event
)
122 ret
= lttng_create_ftrace_event(name
, event
);
126 event
->u
.ftrace
.symbol_name
= kstrdup(symbol_name
, GFP_KERNEL
);
127 if (!event
->u
.ftrace
.symbol_name
)
130 /* Ensure the memory we just allocated don't trigger page faults */
131 wrapper_vmalloc_sync_all();
133 ret
= wrapper_register_ftrace_function_probe(event
->u
.ftrace
.symbol_name
,
134 <tng_ftrace_ops
, event
);
140 kfree(event
->u
.ftrace
.symbol_name
);
142 kfree(event
->desc
->name
);
147 EXPORT_SYMBOL_GPL(lttng_ftrace_register
);
149 void lttng_ftrace_unregister(struct ltt_event
*event
)
151 wrapper_unregister_ftrace_function_probe(event
->u
.ftrace
.symbol_name
,
152 <tng_ftrace_ops
, event
);
154 EXPORT_SYMBOL_GPL(lttng_ftrace_unregister
);
156 void lttng_ftrace_destroy_private(struct ltt_event
*event
)
158 kfree(event
->u
.ftrace
.symbol_name
);
159 kfree(event
->desc
->fields
);
160 kfree(event
->desc
->name
);
163 EXPORT_SYMBOL_GPL(lttng_ftrace_destroy_private
);
165 int lttng_ftrace_init(void)
167 wrapper_vmalloc_sync_all();
170 module_init(lttng_ftrace_init
)
173 * Ftrace takes care of waiting for a grace period (RCU sched) at probe
174 * unregistration, and disables preemption around probe call.
176 void lttng_ftrace_exit(void)
179 module_exit(lttng_ftrace_exit
)
181 MODULE_LICENSE("GPL and additional rights");
182 MODULE_AUTHOR("Mathieu Desnoyers");
183 MODULE_DESCRIPTION("Linux Trace Toolkit Ftrace Support");