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_common
*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_common
*event
= lttng_krp
->event
[type
];
42 struct lttng_kernel_probe_ctx lttng_probe_ctx
= {
44 .interruptible
= !lttng_regs_irqs_disabled(regs
),
48 unsigned long parent_ip
;
51 switch (event
->type
) {
52 case LTTNG_KERNEL_EVENT_TYPE_RECORDER
:
54 struct lttng_kernel_event_recorder
*event_recorder
=
55 container_of(event
, struct lttng_kernel_event_recorder
, parent
);
56 struct lttng_kernel_channel_buffer
*chan
= event_recorder
->chan
;
58 if (unlikely(!LTTNG_READ_ONCE(chan
->parent
.session
->active
)))
60 if (unlikely(!LTTNG_READ_ONCE(chan
->parent
.enabled
)))
64 case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER
: /* Fall-through. */
69 if (unlikely(!LTTNG_READ_ONCE(event
->enabled
)))
72 switch (event
->type
) {
73 case LTTNG_KERNEL_EVENT_TYPE_RECORDER
:
75 struct lttng_kernel_event_recorder
*event_recorder
=
76 container_of(event
, struct lttng_kernel_event_recorder
, parent
);
77 struct lttng_kernel_channel_buffer
*chan
= event_recorder
->chan
;
78 struct lttng_kernel_ring_buffer_ctx ctx
;
81 payload
.ip
= (unsigned long) lttng_get_kretprobe(krpi
)->kp
.addr
;
82 payload
.parent_ip
= (unsigned long) krpi
->ret_addr
;
84 lib_ring_buffer_ctx_init(&ctx
, event_recorder
, sizeof(payload
),
85 lttng_alignof(payload
), <tng_probe_ctx
);
86 ret
= chan
->ops
->event_reserve(&ctx
);
89 lib_ring_buffer_align_ctx(&ctx
, lttng_alignof(payload
));
90 chan
->ops
->event_write(&ctx
, &payload
, sizeof(payload
));
91 chan
->ops
->event_commit(&ctx
);
94 case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER
: /* Fall-through. */
102 int lttng_kretprobes_handler_entry(struct kretprobe_instance
*krpi
,
103 struct pt_regs
*regs
)
105 return _lttng_kretprobes_handler(krpi
, regs
, EVENT_ENTRY
);
109 int lttng_kretprobes_handler_exit(struct kretprobe_instance
*krpi
,
110 struct pt_regs
*regs
)
112 return _lttng_kretprobes_handler(krpi
, regs
, EVENT_EXIT
);
115 static const struct lttng_kernel_event_field
*event_fields
[] = {
116 lttng_kernel_static_event_field("ip",
117 lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER
, 16),
118 false, false, false),
119 lttng_kernel_static_event_field("parent_ip",
120 lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER
, 16),
121 false, false, false),
124 static const struct lttng_kernel_tracepoint_class tp_class
= {
125 .nr_fields
= ARRAY_SIZE(event_fields
),
126 .fields
= event_fields
,
130 * Create event description
133 int lttng_create_kprobe_event(const char *name
, struct lttng_kernel_event_recorder
*event_recorder
,
134 enum lttng_kretprobe_type type
)
136 struct lttng_kernel_event_desc
*desc
;
139 const char *suffix
= NULL
;
142 desc
= kzalloc(sizeof(*desc
), GFP_KERNEL
);
145 name_len
= strlen(name
);
154 name_len
+= strlen(suffix
);
155 alloc_name
= kmalloc(name_len
+ 1, GFP_KERNEL
);
160 strcpy(alloc_name
, name
);
161 strcat(alloc_name
, suffix
);
162 desc
->event_name
= alloc_name
;
163 desc
->tp_class
= &tp_class
;
164 desc
->owner
= THIS_MODULE
;
165 event_recorder
->priv
->parent
.desc
= desc
;
174 int lttng_kretprobes_register(const char *name
,
175 const char *symbol_name
,
178 struct lttng_kernel_event_recorder
*event_recorder_entry
,
179 struct lttng_kernel_event_recorder
*event_recorder_exit
)
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_recorder_entry
, EVENT_ENTRY
);
191 ret
= lttng_create_kprobe_event(name
, event_recorder_exit
, EVENT_EXIT
);
193 goto event_exit_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_exit
;
202 alloc_symbol
= kstrdup(symbol_name
, GFP_KERNEL
);
207 lttng_krp
->krp
.kp
.symbol_name
=
209 event_recorder_entry
->priv
->parent
.u
.kretprobe
.symbol_name
=
211 event_recorder_exit
->priv
->parent
.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_recorder_entry
->parent
;
219 lttng_krp
->event
[EVENT_EXIT
] = &event_recorder_exit
->parent
;
220 event_recorder_entry
->priv
->parent
.u
.kretprobe
.lttng_krp
= lttng_krp
;
221 event_recorder_exit
->priv
->parent
.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_mappings();
239 ret
= register_kretprobe(<tng_krp
->krp
);
245 kfree(lttng_krp
->krp
.kp
.symbol_name
);
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
->event_name
);
253 kfree(event_recorder_entry
->priv
->parent
.desc
);
257 EXPORT_SYMBOL_GPL(lttng_kretprobes_register
);
260 void _lttng_kretprobes_unregister_release(struct kref
*kref
)
262 struct lttng_krp
*lttng_krp
=
263 container_of(kref
, struct lttng_krp
, kref_register
);
264 unregister_kretprobe(<tng_krp
->krp
);
267 void lttng_kretprobes_unregister(struct lttng_kernel_event_recorder
*event_recorder
)
269 kref_put(&event_recorder
->priv
->parent
.u
.kretprobe
.lttng_krp
->kref_register
,
270 _lttng_kretprobes_unregister_release
);
272 EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister
);
275 void _lttng_kretprobes_release(struct kref
*kref
)
277 struct lttng_krp
*lttng_krp
=
278 container_of(kref
, struct lttng_krp
, kref_alloc
);
279 kfree(lttng_krp
->krp
.kp
.symbol_name
);
282 void lttng_kretprobes_destroy_private(struct lttng_kernel_event_recorder
*event_recorder
)
284 kfree(event_recorder
->priv
->parent
.desc
->event_name
);
285 kfree(event_recorder
->priv
->parent
.desc
);
286 kref_put(&event_recorder
->priv
->parent
.u
.kretprobe
.lttng_krp
->kref_alloc
,
287 _lttng_kretprobes_release
);
289 EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private
);
291 int lttng_kretprobes_event_enable_state(struct lttng_kernel_event_common
*event
,
294 struct lttng_kernel_event_common
*event_exit
;
295 struct lttng_krp
*lttng_krp
;
297 if (event
->priv
->instrumentation
!= LTTNG_KERNEL_ABI_KRETPROBE
) {
300 if (event
->enabled
== enable
) {
303 lttng_krp
= event
->priv
->u
.kretprobe
.lttng_krp
;
304 event_exit
= lttng_krp
->event
[EVENT_EXIT
];
305 WRITE_ONCE(event
->enabled
, enable
);
306 WRITE_ONCE(event_exit
->enabled
, enable
);
309 EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state
);
311 MODULE_LICENSE("GPL and additional rights");
312 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
313 MODULE_DESCRIPTION("LTTng kretprobes probes");
314 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION
) "."
315 __stringify(LTTNG_MODULES_MINOR_VERSION
) "."
316 __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION
)
317 LTTNG_MODULES_EXTRAVERSION
);