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 <linux/kprobes.h>
12 #include <linux/slab.h>
13 #include <linux/kref.h>
14 #include <lttng-events.h>
15 #include <include/ringbuffer/frontend_types.h>
16 #include <wrapper/irqflags.h>
17 #include <lttng-tracer.h>
19 enum lttng_kretprobe_type
{
26 struct lttng_event
*event
[2]; /* ENTRY and RETURN */
27 struct kref kref_register
;
28 struct kref kref_alloc
;
32 int _lttng_kretprobes_handler(struct kretprobe_instance
*krpi
,
34 enum lttng_kretprobe_type type
)
36 struct lttng_krp
*lttng_krp
=
37 container_of(krpi
->rp
, struct lttng_krp
, krp
);
38 struct lttng_event
*event
=
39 lttng_krp
->event
[type
];
40 struct lttng_probe_ctx lttng_probe_ctx
= {
42 .interruptible
= !lttng_regs_irqs_disabled(regs
),
44 struct lttng_channel
*chan
= event
->chan
;
45 struct lib_ring_buffer_ctx ctx
;
49 unsigned long parent_ip
;
52 if (unlikely(!READ_ONCE(chan
->session
->active
)))
54 if (unlikely(!READ_ONCE(chan
->enabled
)))
56 if (unlikely(!READ_ONCE(event
->enabled
)))
59 payload
.ip
= (unsigned long) krpi
->rp
->kp
.addr
;
60 payload
.parent_ip
= (unsigned long) krpi
->ret_addr
;
62 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, <tng_probe_ctx
, sizeof(payload
),
63 lttng_alignof(payload
), -1);
64 ret
= chan
->ops
->event_reserve(&ctx
, event
->id
);
67 lib_ring_buffer_align_ctx(&ctx
, lttng_alignof(payload
));
68 chan
->ops
->event_write(&ctx
, &payload
, sizeof(payload
));
69 chan
->ops
->event_commit(&ctx
);
74 int lttng_kretprobes_handler_entry(struct kretprobe_instance
*krpi
,
77 return _lttng_kretprobes_handler(krpi
, regs
, EVENT_ENTRY
);
81 int lttng_kretprobes_handler_return(struct kretprobe_instance
*krpi
,
84 return _lttng_kretprobes_handler(krpi
, regs
, EVENT_RETURN
);
88 * Create event description
91 int lttng_create_kprobe_event(const char *name
, struct lttng_event
*event
,
92 enum lttng_kretprobe_type type
)
94 struct lttng_event_field
*fields
;
95 struct lttng_event_desc
*desc
;
99 const char *suffix
= NULL
;
101 desc
= kzalloc(sizeof(*event
->desc
), GFP_KERNEL
);
104 name_len
= strlen(name
);
113 name_len
+= strlen(suffix
);
114 alloc_name
= kmalloc(name_len
+ 1, GFP_KERNEL
);
119 strcpy(alloc_name
, name
);
120 strcat(alloc_name
, suffix
);
121 desc
->name
= alloc_name
;
123 desc
->fields
= fields
=
124 kzalloc(2 * sizeof(struct lttng_event_field
), GFP_KERNEL
);
129 fields
[0].name
= "ip";
130 fields
[0].type
.atype
= atype_integer
;
131 fields
[0].type
.u
.integer
.size
= sizeof(unsigned long) * CHAR_BIT
;
132 fields
[0].type
.u
.integer
.alignment
= lttng_alignof(unsigned long) * CHAR_BIT
;
133 fields
[0].type
.u
.integer
.signedness
= lttng_is_signed_type(unsigned long);
134 fields
[0].type
.u
.integer
.reverse_byte_order
= 0;
135 fields
[0].type
.u
.integer
.base
= 16;
136 fields
[0].type
.u
.integer
.encoding
= lttng_encode_none
;
138 fields
[1].name
= "parent_ip";
139 fields
[1].type
.atype
= atype_integer
;
140 fields
[1].type
.u
.integer
.size
= sizeof(unsigned long) * CHAR_BIT
;
141 fields
[1].type
.u
.integer
.alignment
= lttng_alignof(unsigned long) * CHAR_BIT
;
142 fields
[1].type
.u
.integer
.signedness
= lttng_is_signed_type(unsigned long);
143 fields
[1].type
.u
.integer
.reverse_byte_order
= 0;
144 fields
[1].type
.u
.integer
.base
= 16;
145 fields
[1].type
.u
.integer
.encoding
= lttng_encode_none
;
147 desc
->owner
= THIS_MODULE
;
159 int lttng_kretprobes_register(const char *name
,
160 const char *symbol_name
,
163 struct lttng_event
*event_entry
,
164 struct lttng_event
*event_return
)
167 struct lttng_krp
*lttng_krp
;
169 /* Kprobes expects a NULL symbol name if unused */
170 if (symbol_name
[0] == '\0')
173 ret
= lttng_create_kprobe_event(name
, event_entry
, EVENT_ENTRY
);
176 ret
= lttng_create_kprobe_event(name
, event_return
, EVENT_RETURN
);
178 goto event_return_error
;
179 lttng_krp
= kzalloc(sizeof(*lttng_krp
), GFP_KERNEL
);
182 lttng_krp
->krp
.entry_handler
= lttng_kretprobes_handler_entry
;
183 lttng_krp
->krp
.handler
= lttng_kretprobes_handler_return
;
187 alloc_symbol
= kstrdup(symbol_name
, GFP_KERNEL
);
192 lttng_krp
->krp
.kp
.symbol_name
=
194 event_entry
->u
.kretprobe
.symbol_name
=
196 event_return
->u
.kretprobe
.symbol_name
=
199 lttng_krp
->krp
.kp
.offset
= offset
;
200 lttng_krp
->krp
.kp
.addr
= (void *) (unsigned long) addr
;
202 /* Allow probe handler to find event structures */
203 lttng_krp
->event
[EVENT_ENTRY
] = event_entry
;
204 lttng_krp
->event
[EVENT_RETURN
] = event_return
;
205 event_entry
->u
.kretprobe
.lttng_krp
= lttng_krp
;
206 event_return
->u
.kretprobe
.lttng_krp
= lttng_krp
;
209 * Both events must be unregistered before the kretprobe is
210 * unregistered. Same for memory allocation.
212 kref_init(<tng_krp
->kref_alloc
);
213 kref_get(<tng_krp
->kref_alloc
); /* inc refcount to 2, no overflow. */
214 kref_init(<tng_krp
->kref_register
);
215 kref_get(<tng_krp
->kref_register
); /* inc refcount to 2, no overflow. */
217 ret
= register_kretprobe(<tng_krp
->krp
);
223 kfree(lttng_krp
->krp
.kp
.symbol_name
);
227 kfree(event_return
->desc
->fields
);
228 kfree(event_return
->desc
->name
);
229 kfree(event_return
->desc
);
231 kfree(event_entry
->desc
->fields
);
232 kfree(event_entry
->desc
->name
);
233 kfree(event_entry
->desc
);
237 EXPORT_SYMBOL_GPL(lttng_kretprobes_register
);
240 void _lttng_kretprobes_unregister_release(struct kref
*kref
)
242 struct lttng_krp
*lttng_krp
=
243 container_of(kref
, struct lttng_krp
, kref_register
);
244 unregister_kretprobe(<tng_krp
->krp
);
247 void lttng_kretprobes_unregister(struct lttng_event
*event
)
249 kref_put(&event
->u
.kretprobe
.lttng_krp
->kref_register
,
250 _lttng_kretprobes_unregister_release
);
252 EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister
);
255 void _lttng_kretprobes_release(struct kref
*kref
)
257 struct lttng_krp
*lttng_krp
=
258 container_of(kref
, struct lttng_krp
, kref_alloc
);
259 kfree(lttng_krp
->krp
.kp
.symbol_name
);
262 void lttng_kretprobes_destroy_private(struct lttng_event
*event
)
264 kfree(event
->desc
->fields
);
265 kfree(event
->desc
->name
);
267 kref_put(&event
->u
.kretprobe
.lttng_krp
->kref_alloc
,
268 _lttng_kretprobes_release
);
270 EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private
);
272 int lttng_kretprobes_event_enable_state(struct lttng_event
*event
,
275 struct lttng_event
*event_return
;
276 struct lttng_krp
*lttng_krp
;
278 if (event
->instrumentation
!= LTTNG_KERNEL_KRETPROBE
) {
281 if (event
->enabled
== enable
) {
284 lttng_krp
= event
->u
.kretprobe
.lttng_krp
;
285 event_return
= lttng_krp
->event
[EVENT_RETURN
];
286 WRITE_ONCE(event
->enabled
, enable
);
287 WRITE_ONCE(event_return
->enabled
, enable
);
290 EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state
);
292 MODULE_LICENSE("GPL and additional rights");
293 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
294 MODULE_DESCRIPTION("LTTng kretprobes probes");
295 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION
) "."
296 __stringify(LTTNG_MODULES_MINOR_VERSION
) "."
297 __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION
)
298 LTTNG_MODULES_EXTRAVERSION
);