2 * probes/lttng-kretprobes.c
4 * LTTng kretprobes integration module.
6 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; only
11 * version 2.1 of the License.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include <linux/module.h>
24 #include <linux/kprobes.h>
25 #include <linux/slab.h>
26 #include <linux/kref.h>
27 #include <lttng-events.h>
28 #include <wrapper/ringbuffer/frontend_types.h>
29 #include <wrapper/vmalloc.h>
30 #include <wrapper/irqflags.h>
31 #include <lttng-tracer.h>
32 #include <blacklist/kprobes.h>
34 enum lttng_kretprobe_type
{
41 struct lttng_event
*event
[2]; /* ENTRY and RETURN */
42 struct kref kref_register
;
43 struct kref kref_alloc
;
47 int _lttng_kretprobes_handler(struct kretprobe_instance
*krpi
,
49 enum lttng_kretprobe_type type
)
51 struct lttng_krp
*lttng_krp
=
52 container_of(krpi
->rp
, struct lttng_krp
, krp
);
53 struct lttng_event
*event
=
54 lttng_krp
->event
[type
];
55 struct lttng_probe_ctx lttng_probe_ctx
= {
57 .interruptible
= !lttng_regs_irqs_disabled(regs
),
59 struct lttng_channel
*chan
= event
->chan
;
60 struct lib_ring_buffer_ctx ctx
;
64 unsigned long parent_ip
;
67 if (unlikely(!READ_ONCE(chan
->session
->active
)))
69 if (unlikely(!READ_ONCE(chan
->enabled
)))
71 if (unlikely(!READ_ONCE(event
->enabled
)))
74 payload
.ip
= (unsigned long) krpi
->rp
->kp
.addr
;
75 payload
.parent_ip
= (unsigned long) krpi
->ret_addr
;
77 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, <tng_probe_ctx
, sizeof(payload
),
78 lttng_alignof(payload
), -1);
79 ret
= chan
->ops
->event_reserve(&ctx
, event
->id
);
82 lib_ring_buffer_align_ctx(&ctx
, lttng_alignof(payload
));
83 chan
->ops
->event_write(&ctx
, &payload
, sizeof(payload
));
84 chan
->ops
->event_commit(&ctx
);
89 int lttng_kretprobes_handler_entry(struct kretprobe_instance
*krpi
,
92 return _lttng_kretprobes_handler(krpi
, regs
, EVENT_ENTRY
);
96 int lttng_kretprobes_handler_return(struct kretprobe_instance
*krpi
,
99 return _lttng_kretprobes_handler(krpi
, regs
, EVENT_RETURN
);
103 * Create event description
106 int lttng_create_kprobe_event(const char *name
, struct lttng_event
*event
,
107 enum lttng_kretprobe_type type
)
109 struct lttng_event_field
*fields
;
110 struct lttng_event_desc
*desc
;
114 const char *suffix
= NULL
;
116 desc
= kzalloc(sizeof(*event
->desc
), GFP_KERNEL
);
119 name_len
= strlen(name
);
128 name_len
+= strlen(suffix
);
129 alloc_name
= kmalloc(name_len
+ 1, GFP_KERNEL
);
134 strcpy(alloc_name
, name
);
135 strcat(alloc_name
, suffix
);
136 desc
->name
= alloc_name
;
138 desc
->fields
= fields
=
139 kzalloc(2 * sizeof(struct lttng_event_field
), GFP_KERNEL
);
144 fields
[0].name
= "ip";
145 fields
[0].type
.atype
= atype_integer
;
146 fields
[0].type
.u
.basic
.integer
.size
= sizeof(unsigned long) * CHAR_BIT
;
147 fields
[0].type
.u
.basic
.integer
.alignment
= lttng_alignof(unsigned long) * CHAR_BIT
;
148 fields
[0].type
.u
.basic
.integer
.signedness
= lttng_is_signed_type(unsigned long);
149 fields
[0].type
.u
.basic
.integer
.reverse_byte_order
= 0;
150 fields
[0].type
.u
.basic
.integer
.base
= 16;
151 fields
[0].type
.u
.basic
.integer
.encoding
= lttng_encode_none
;
153 fields
[1].name
= "parent_ip";
154 fields
[1].type
.atype
= atype_integer
;
155 fields
[1].type
.u
.basic
.integer
.size
= sizeof(unsigned long) * CHAR_BIT
;
156 fields
[1].type
.u
.basic
.integer
.alignment
= lttng_alignof(unsigned long) * CHAR_BIT
;
157 fields
[1].type
.u
.basic
.integer
.signedness
= lttng_is_signed_type(unsigned long);
158 fields
[1].type
.u
.basic
.integer
.reverse_byte_order
= 0;
159 fields
[1].type
.u
.basic
.integer
.base
= 16;
160 fields
[1].type
.u
.basic
.integer
.encoding
= lttng_encode_none
;
162 desc
->owner
= THIS_MODULE
;
174 int lttng_kretprobes_register(const char *name
,
175 const char *symbol_name
,
178 struct lttng_event
*event_entry
,
179 struct lttng_event
*event_return
)
182 struct lttng_krp
*lttng_krp
;
184 /* Kprobes expects a NULL symbol name if unused */
185 if (symbol_name
[0] == '\0')
188 ret
= lttng_create_kprobe_event(name
, event_entry
, EVENT_ENTRY
);
191 ret
= lttng_create_kprobe_event(name
, event_return
, EVENT_RETURN
);
193 goto event_return_error
;
194 lttng_krp
= kzalloc(sizeof(*lttng_krp
), GFP_KERNEL
);
197 lttng_krp
->krp
.entry_handler
= lttng_kretprobes_handler_entry
;
198 lttng_krp
->krp
.handler
= lttng_kretprobes_handler_return
;
202 alloc_symbol
= kstrdup(symbol_name
, GFP_KERNEL
);
207 lttng_krp
->krp
.kp
.symbol_name
=
209 event_entry
->u
.kretprobe
.symbol_name
=
211 event_return
->u
.kretprobe
.symbol_name
=
214 lttng_krp
->krp
.kp
.offset
= offset
;
215 lttng_krp
->krp
.kp
.addr
= (void *) (unsigned long) addr
;
217 /* Allow probe handler to find event structures */
218 lttng_krp
->event
[EVENT_ENTRY
] = event_entry
;
219 lttng_krp
->event
[EVENT_RETURN
] = event_return
;
220 event_entry
->u
.kretprobe
.lttng_krp
= lttng_krp
;
221 event_return
->u
.kretprobe
.lttng_krp
= lttng_krp
;
224 * Both events must be unregistered before the kretprobe is
225 * unregistered. Same for memory allocation.
227 kref_init(<tng_krp
->kref_alloc
);
228 kref_get(<tng_krp
->kref_alloc
); /* inc refcount to 2, no overflow. */
229 kref_init(<tng_krp
->kref_register
);
230 kref_get(<tng_krp
->kref_register
); /* inc refcount to 2, no overflow. */
233 * Ensure the memory we just allocated don't trigger page faults.
234 * Well.. kprobes itself puts the page fault handler on the blacklist,
235 * but we can never be too careful.
237 wrapper_vmalloc_sync_all();
239 ret
= register_kretprobe(<tng_krp
->krp
);
245 kfree(lttng_krp
->krp
.kp
.symbol_name
);
249 kfree(event_return
->desc
->fields
);
250 kfree(event_return
->desc
->name
);
251 kfree(event_return
->desc
);
253 kfree(event_entry
->desc
->fields
);
254 kfree(event_entry
->desc
->name
);
255 kfree(event_entry
->desc
);
259 EXPORT_SYMBOL_GPL(lttng_kretprobes_register
);
262 void _lttng_kretprobes_unregister_release(struct kref
*kref
)
264 struct lttng_krp
*lttng_krp
=
265 container_of(kref
, struct lttng_krp
, kref_register
);
266 unregister_kretprobe(<tng_krp
->krp
);
269 void lttng_kretprobes_unregister(struct lttng_event
*event
)
271 kref_put(&event
->u
.kretprobe
.lttng_krp
->kref_register
,
272 _lttng_kretprobes_unregister_release
);
274 EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister
);
277 void _lttng_kretprobes_release(struct kref
*kref
)
279 struct lttng_krp
*lttng_krp
=
280 container_of(kref
, struct lttng_krp
, kref_alloc
);
281 kfree(lttng_krp
->krp
.kp
.symbol_name
);
284 void lttng_kretprobes_destroy_private(struct lttng_event
*event
)
286 kfree(event
->desc
->fields
);
287 kfree(event
->desc
->name
);
289 kref_put(&event
->u
.kretprobe
.lttng_krp
->kref_alloc
,
290 _lttng_kretprobes_release
);
292 EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private
);
294 int lttng_kretprobes_event_enable_state(struct lttng_event
*event
,
297 struct lttng_event
*event_return
;
298 struct lttng_krp
*lttng_krp
;
300 if (event
->instrumentation
!= LTTNG_KERNEL_KRETPROBE
) {
303 if (event
->enabled
== enable
) {
306 lttng_krp
= event
->u
.kretprobe
.lttng_krp
;
307 event_return
= lttng_krp
->event
[EVENT_RETURN
];
308 WRITE_ONCE(event
->enabled
, enable
);
309 WRITE_ONCE(event_return
->enabled
, enable
);
312 EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state
);
314 MODULE_LICENSE("GPL and additional rights");
315 MODULE_AUTHOR("Mathieu Desnoyers");
316 MODULE_DESCRIPTION("Linux Trace Toolkit Kretprobes Support");
317 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION
) "."
318 __stringify(LTTNG_MODULES_MINOR_VERSION
) "."
319 __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION
)
320 LTTNG_MODULES_EXTRAVERSION
);