1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
3 * probes/lttng-kretprobes.c
5 * LTTng kretprobes integration module.
7 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10 #include <linux/module.h>
11 #include <wrapper/kprobes.h>
12 #include <linux/slab.h>
13 #include <linux/kref.h>
14 #include <lttng/events.h>
15 #include <lttng/events-internal.h>
16 #include <ringbuffer/frontend_types.h>
17 #include <wrapper/vmalloc.h>
18 #include <wrapper/irqflags.h>
19 #include <lttng/tracer.h>
20 #include <blacklist/kprobes.h>
22 enum lttng_kretprobe_type
{
29 struct lttng_kernel_event_recorder
*event
[2]; /* ENTRY and EXIT */
30 struct kref kref_register
;
31 struct kref kref_alloc
;
35 int _lttng_kretprobes_handler(struct kretprobe_instance
*krpi
,
37 enum lttng_kretprobe_type type
)
39 struct lttng_krp
*lttng_krp
=
40 container_of(lttng_get_kretprobe(krpi
), struct lttng_krp
, krp
);
41 struct lttng_kernel_event_recorder
*event_recorder
=
42 lttng_krp
->event
[type
];
43 struct lttng_probe_ctx lttng_probe_ctx
= {
44 .event
= event_recorder
,
45 .interruptible
= !lttng_regs_irqs_disabled(regs
),
47 struct lttng_channel
*chan
= event_recorder
->chan
;
48 struct lib_ring_buffer_ctx ctx
;
52 unsigned long parent_ip
;
55 if (unlikely(!LTTNG_READ_ONCE(chan
->session
->active
)))
57 if (unlikely(!LTTNG_READ_ONCE(chan
->enabled
)))
59 if (unlikely(!LTTNG_READ_ONCE(event_recorder
->parent
.enabled
)))
62 payload
.ip
= (unsigned long) lttng_get_kretprobe(krpi
)->kp
.addr
;
63 payload
.parent_ip
= (unsigned long) krpi
->ret_addr
;
65 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, <tng_probe_ctx
, sizeof(payload
),
66 lttng_alignof(payload
), -1);
67 ret
= chan
->ops
->event_reserve(&ctx
, event_recorder
->priv
->id
);
70 lib_ring_buffer_align_ctx(&ctx
, lttng_alignof(payload
));
71 chan
->ops
->event_write(&ctx
, &payload
, sizeof(payload
));
72 chan
->ops
->event_commit(&ctx
);
77 int lttng_kretprobes_handler_entry(struct kretprobe_instance
*krpi
,
80 return _lttng_kretprobes_handler(krpi
, regs
, EVENT_ENTRY
);
84 int lttng_kretprobes_handler_exit(struct kretprobe_instance
*krpi
,
87 return _lttng_kretprobes_handler(krpi
, regs
, EVENT_EXIT
);
90 static const struct lttng_kernel_type_common
*event_type
=
91 lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER
, 16);
94 * Create event description
97 int lttng_create_kprobe_event(const char *name
, struct lttng_kernel_event_recorder
*event_recorder
,
98 enum lttng_kretprobe_type type
)
100 const struct lttng_kernel_event_field
**fieldp_array
;
101 struct lttng_kernel_event_field
*field
;
102 struct lttng_kernel_event_desc
*desc
;
105 const char *suffix
= NULL
;
108 desc
= kzalloc(sizeof(*desc
), GFP_KERNEL
);
111 name_len
= strlen(name
);
120 name_len
+= strlen(suffix
);
121 alloc_name
= kmalloc(name_len
+ 1, GFP_KERNEL
);
126 strcpy(alloc_name
, name
);
127 strcat(alloc_name
, suffix
);
128 desc
->event_name
= alloc_name
;
130 fieldp_array
= kzalloc(desc
->nr_fields
* sizeof(struct lttng_kernel_event_field
*), GFP_KERNEL
);
133 goto error_fieldp_array
;
135 desc
->fields
= fieldp_array
;
137 field
= kzalloc(sizeof(struct lttng_kernel_event_field
), GFP_KERNEL
);
143 field
->type
= event_type
;
144 desc
->fields
[0] = field
;
146 field
= kzalloc(sizeof(struct lttng_kernel_event_field
), GFP_KERNEL
);
151 field
->name
= "parent_ip";
152 field
->type
= event_type
;
153 desc
->fields
[1] = field
;
155 desc
->owner
= THIS_MODULE
;
156 event_recorder
->priv
->parent
.desc
= desc
;
161 kfree(desc
->fields
[0]);
165 kfree(desc
->event_name
);
171 int lttng_kretprobes_register(const char *name
,
172 const char *symbol_name
,
175 struct lttng_kernel_event_recorder
*event_recorder_entry
,
176 struct lttng_kernel_event_recorder
*event_recorder_exit
)
179 struct lttng_krp
*lttng_krp
;
181 /* Kprobes expects a NULL symbol name if unused */
182 if (symbol_name
[0] == '\0')
185 ret
= lttng_create_kprobe_event(name
, event_recorder_entry
, EVENT_ENTRY
);
188 ret
= lttng_create_kprobe_event(name
, event_recorder_exit
, EVENT_EXIT
);
190 goto event_exit_error
;
191 lttng_krp
= kzalloc(sizeof(*lttng_krp
), GFP_KERNEL
);
194 lttng_krp
->krp
.entry_handler
= lttng_kretprobes_handler_entry
;
195 lttng_krp
->krp
.handler
= lttng_kretprobes_handler_exit
;
199 alloc_symbol
= kstrdup(symbol_name
, GFP_KERNEL
);
204 lttng_krp
->krp
.kp
.symbol_name
=
206 event_recorder_entry
->priv
->parent
.u
.kretprobe
.symbol_name
=
208 event_recorder_exit
->priv
->parent
.u
.kretprobe
.symbol_name
=
211 lttng_krp
->krp
.kp
.offset
= offset
;
212 lttng_krp
->krp
.kp
.addr
= (void *) (unsigned long) addr
;
214 /* Allow probe handler to find event structures */
215 lttng_krp
->event
[EVENT_ENTRY
] = event_recorder_entry
;
216 lttng_krp
->event
[EVENT_EXIT
] = event_recorder_exit
;
217 event_recorder_entry
->priv
->parent
.u
.kretprobe
.lttng_krp
= lttng_krp
;
218 event_recorder_exit
->priv
->parent
.u
.kretprobe
.lttng_krp
= lttng_krp
;
221 * Both events must be unregistered before the kretprobe is
222 * unregistered. Same for memory allocation.
224 kref_init(<tng_krp
->kref_alloc
);
225 kref_get(<tng_krp
->kref_alloc
); /* inc refcount to 2, no overflow. */
226 kref_init(<tng_krp
->kref_register
);
227 kref_get(<tng_krp
->kref_register
); /* inc refcount to 2, no overflow. */
230 * Ensure the memory we just allocated don't trigger page faults.
231 * Well.. kprobes itself puts the page fault handler on the blacklist,
232 * but we can never be too careful.
234 wrapper_vmalloc_sync_mappings();
236 ret
= register_kretprobe(<tng_krp
->krp
);
242 kfree(lttng_krp
->krp
.kp
.symbol_name
);
246 kfree(event_recorder_exit
->priv
->parent
.desc
->fields
[0]);
247 kfree(event_recorder_exit
->priv
->parent
.desc
->fields
[1]);
248 kfree(event_recorder_exit
->priv
->parent
.desc
->fields
);
249 kfree(event_recorder_exit
->priv
->parent
.desc
->event_name
);
250 kfree(event_recorder_exit
->priv
->parent
.desc
);
252 kfree(event_recorder_entry
->priv
->parent
.desc
->fields
[0]);
253 kfree(event_recorder_entry
->priv
->parent
.desc
->fields
[1]);
254 kfree(event_recorder_entry
->priv
->parent
.desc
->fields
);
255 kfree(event_recorder_entry
->priv
->parent
.desc
->event_name
);
256 kfree(event_recorder_entry
->priv
->parent
.desc
);
260 EXPORT_SYMBOL_GPL(lttng_kretprobes_register
);
263 void _lttng_kretprobes_unregister_release(struct kref
*kref
)
265 struct lttng_krp
*lttng_krp
=
266 container_of(kref
, struct lttng_krp
, kref_register
);
267 unregister_kretprobe(<tng_krp
->krp
);
270 void lttng_kretprobes_unregister(struct lttng_kernel_event_recorder
*event_recorder
)
272 kref_put(&event_recorder
->priv
->parent
.u
.kretprobe
.lttng_krp
->kref_register
,
273 _lttng_kretprobes_unregister_release
);
275 EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister
);
278 void _lttng_kretprobes_release(struct kref
*kref
)
280 struct lttng_krp
*lttng_krp
=
281 container_of(kref
, struct lttng_krp
, kref_alloc
);
282 kfree(lttng_krp
->krp
.kp
.symbol_name
);
285 void lttng_kretprobes_destroy_private(struct lttng_kernel_event_recorder
*event_recorder
)
287 kfree(event_recorder
->priv
->parent
.desc
->fields
[0]);
288 kfree(event_recorder
->priv
->parent
.desc
->fields
[1]);
289 kfree(event_recorder
->priv
->parent
.desc
->fields
);
290 kfree(event_recorder
->priv
->parent
.desc
->event_name
);
291 kfree(event_recorder
->priv
->parent
.desc
);
292 kref_put(&event_recorder
->priv
->parent
.u
.kretprobe
.lttng_krp
->kref_alloc
,
293 _lttng_kretprobes_release
);
295 EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private
);
297 int lttng_kretprobes_event_enable_state(struct lttng_kernel_event_recorder
*event_recorder
,
300 struct lttng_kernel_event_recorder
*event_recorder_exit
;
301 struct lttng_krp
*lttng_krp
;
303 if (event_recorder
->priv
->parent
.instrumentation
!= LTTNG_KERNEL_ABI_KRETPROBE
) {
306 if (event_recorder
->parent
.enabled
== enable
) {
309 lttng_krp
= event_recorder
->priv
->parent
.u
.kretprobe
.lttng_krp
;
310 event_recorder_exit
= lttng_krp
->event
[EVENT_EXIT
];
311 WRITE_ONCE(event_recorder
->parent
.enabled
, enable
);
312 WRITE_ONCE(event_recorder_exit
->parent
.enabled
, enable
);
315 EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state
);
317 MODULE_LICENSE("GPL and additional rights");
318 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
319 MODULE_DESCRIPTION("LTTng kretprobes probes");
320 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION
) "."
321 __stringify(LTTNG_MODULES_MINOR_VERSION
) "."
322 __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION
)
323 LTTNG_MODULES_EXTRAVERSION
);