Commit | Line | Data |
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7371f44c | 1 | /* |
ccecf3fb | 2 | * probes/lttng-kretprobes.c |
7371f44c MD |
3 | * |
4 | * LTTng kretprobes integration module. | |
5 | * | |
886d51a3 MD |
6 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
7 | * | |
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. | |
12 | * | |
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. | |
17 | * | |
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 | |
7371f44c MD |
21 | */ |
22 | ||
23 | #include <linux/module.h> | |
24 | #include <linux/kprobes.h> | |
25 | #include <linux/slab.h> | |
26 | #include <linux/kref.h> | |
156a3977 MD |
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> | |
7371f44c MD |
32 | |
33 | enum lttng_kretprobe_type { | |
34 | EVENT_ENTRY = 0, | |
35 | EVENT_RETURN = 1, | |
36 | }; | |
37 | ||
38 | struct lttng_krp { | |
39 | struct kretprobe krp; | |
a90917c3 | 40 | struct lttng_event *event[2]; /* ENTRY and RETURN */ |
7371f44c MD |
41 | struct kref kref_register; |
42 | struct kref kref_alloc; | |
43 | }; | |
44 | ||
45 | static | |
46 | int _lttng_kretprobes_handler(struct kretprobe_instance *krpi, | |
47 | struct pt_regs *regs, | |
48 | enum lttng_kretprobe_type type) | |
49 | { | |
50 | struct lttng_krp *lttng_krp = | |
51 | container_of(krpi->rp, struct lttng_krp, krp); | |
a90917c3 | 52 | struct lttng_event *event = |
7371f44c | 53 | lttng_krp->event[type]; |
79150a49 JD |
54 | struct lttng_probe_ctx lttng_probe_ctx = { |
55 | .event = event, | |
ccecf3fb | 56 | .interruptible = !lttng_regs_irqs_disabled(regs), |
79150a49 | 57 | }; |
a90917c3 | 58 | struct lttng_channel *chan = event->chan; |
7371f44c MD |
59 | struct lib_ring_buffer_ctx ctx; |
60 | int ret; | |
61 | struct { | |
62 | unsigned long ip; | |
63 | unsigned long parent_ip; | |
64 | } payload; | |
65 | ||
66 | if (unlikely(!ACCESS_ONCE(chan->session->active))) | |
67 | return 0; | |
68 | if (unlikely(!ACCESS_ONCE(chan->enabled))) | |
69 | return 0; | |
70 | if (unlikely(!ACCESS_ONCE(event->enabled))) | |
71 | return 0; | |
72 | ||
73 | payload.ip = (unsigned long) krpi->rp->kp.addr; | |
74 | payload.parent_ip = (unsigned long) krpi->ret_addr; | |
75 | ||
79150a49 | 76 | lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx, sizeof(payload), |
a90917c3 | 77 | lttng_alignof(payload), -1); |
7371f44c MD |
78 | ret = chan->ops->event_reserve(&ctx, event->id); |
79 | if (ret < 0) | |
80 | return 0; | |
a90917c3 | 81 | lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload)); |
7371f44c MD |
82 | chan->ops->event_write(&ctx, &payload, sizeof(payload)); |
83 | chan->ops->event_commit(&ctx); | |
84 | return 0; | |
85 | } | |
86 | ||
87 | static | |
88 | int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi, | |
89 | struct pt_regs *regs) | |
90 | { | |
91 | return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY); | |
92 | } | |
93 | ||
94 | static | |
95 | int lttng_kretprobes_handler_return(struct kretprobe_instance *krpi, | |
96 | struct pt_regs *regs) | |
97 | { | |
98 | return _lttng_kretprobes_handler(krpi, regs, EVENT_RETURN); | |
99 | } | |
100 | ||
101 | /* | |
102 | * Create event description | |
103 | */ | |
104 | static | |
a90917c3 | 105 | int lttng_create_kprobe_event(const char *name, struct lttng_event *event, |
7371f44c MD |
106 | enum lttng_kretprobe_type type) |
107 | { | |
108 | struct lttng_event_field *fields; | |
109 | struct lttng_event_desc *desc; | |
110 | int ret; | |
111 | char *alloc_name; | |
112 | size_t name_len; | |
113 | const char *suffix = NULL; | |
114 | ||
115 | desc = kzalloc(sizeof(*event->desc), GFP_KERNEL); | |
116 | if (!desc) | |
117 | return -ENOMEM; | |
118 | name_len = strlen(name); | |
119 | switch (type) { | |
120 | case EVENT_ENTRY: | |
121 | suffix = "_entry"; | |
122 | break; | |
123 | case EVENT_RETURN: | |
124 | suffix = "_return"; | |
125 | break; | |
126 | } | |
127 | name_len += strlen(suffix); | |
128 | alloc_name = kmalloc(name_len + 1, GFP_KERNEL); | |
129 | if (!alloc_name) { | |
130 | ret = -ENOMEM; | |
131 | goto error_str; | |
132 | } | |
133 | strcpy(alloc_name, name); | |
134 | strcat(alloc_name, suffix); | |
135 | desc->name = alloc_name; | |
136 | desc->nr_fields = 2; | |
137 | desc->fields = fields = | |
138 | kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL); | |
139 | if (!desc->fields) { | |
140 | ret = -ENOMEM; | |
141 | goto error_fields; | |
142 | } | |
143 | fields[0].name = "ip"; | |
144 | fields[0].type.atype = atype_integer; | |
145 | fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT; | |
a90917c3 | 146 | fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; |
06254b0f | 147 | fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long); |
7371f44c MD |
148 | fields[0].type.u.basic.integer.reverse_byte_order = 0; |
149 | fields[0].type.u.basic.integer.base = 16; | |
150 | fields[0].type.u.basic.integer.encoding = lttng_encode_none; | |
151 | ||
152 | fields[1].name = "parent_ip"; | |
153 | fields[1].type.atype = atype_integer; | |
154 | fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT; | |
a90917c3 | 155 | fields[1].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; |
06254b0f | 156 | fields[1].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long); |
7371f44c MD |
157 | fields[1].type.u.basic.integer.reverse_byte_order = 0; |
158 | fields[1].type.u.basic.integer.base = 16; | |
159 | fields[1].type.u.basic.integer.encoding = lttng_encode_none; | |
160 | ||
161 | desc->owner = THIS_MODULE; | |
162 | event->desc = desc; | |
163 | ||
164 | return 0; | |
165 | ||
166 | error_fields: | |
167 | kfree(desc->name); | |
168 | error_str: | |
169 | kfree(desc); | |
170 | return ret; | |
171 | } | |
172 | ||
173 | int lttng_kretprobes_register(const char *name, | |
174 | const char *symbol_name, | |
175 | uint64_t offset, | |
176 | uint64_t addr, | |
a90917c3 MD |
177 | struct lttng_event *event_entry, |
178 | struct lttng_event *event_return) | |
7371f44c MD |
179 | { |
180 | int ret; | |
181 | struct lttng_krp *lttng_krp; | |
182 | ||
183 | /* Kprobes expects a NULL symbol name if unused */ | |
184 | if (symbol_name[0] == '\0') | |
185 | symbol_name = NULL; | |
186 | ||
187 | ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY); | |
188 | if (ret) | |
189 | goto error; | |
190 | ret = lttng_create_kprobe_event(name, event_return, EVENT_RETURN); | |
191 | if (ret) | |
192 | goto event_return_error; | |
193 | lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL); | |
194 | if (!lttng_krp) | |
195 | goto krp_error; | |
196 | lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry; | |
197 | lttng_krp->krp.handler = lttng_kretprobes_handler_return; | |
198 | if (symbol_name) { | |
199 | char *alloc_symbol; | |
200 | ||
201 | alloc_symbol = kstrdup(symbol_name, GFP_KERNEL); | |
202 | if (!alloc_symbol) { | |
203 | ret = -ENOMEM; | |
204 | goto name_error; | |
205 | } | |
206 | lttng_krp->krp.kp.symbol_name = | |
207 | alloc_symbol; | |
208 | event_entry->u.kretprobe.symbol_name = | |
209 | alloc_symbol; | |
210 | event_return->u.kretprobe.symbol_name = | |
211 | alloc_symbol; | |
212 | } | |
213 | lttng_krp->krp.kp.offset = offset; | |
b2c4e8fb | 214 | lttng_krp->krp.kp.addr = (void *) (unsigned long) addr; |
7371f44c MD |
215 | |
216 | /* Allow probe handler to find event structures */ | |
217 | lttng_krp->event[EVENT_ENTRY] = event_entry; | |
218 | lttng_krp->event[EVENT_RETURN] = event_return; | |
219 | event_entry->u.kretprobe.lttng_krp = lttng_krp; | |
220 | event_return->u.kretprobe.lttng_krp = lttng_krp; | |
221 | ||
222 | /* | |
223 | * Both events must be unregistered before the kretprobe is | |
224 | * unregistered. Same for memory allocation. | |
225 | */ | |
226 | kref_init(<tng_krp->kref_alloc); | |
9c1f4643 | 227 | kref_get(<tng_krp->kref_alloc); /* inc refcount to 2, no overflow. */ |
7371f44c | 228 | kref_init(<tng_krp->kref_register); |
9c1f4643 | 229 | kref_get(<tng_krp->kref_register); /* inc refcount to 2, no overflow. */ |
7371f44c MD |
230 | |
231 | /* | |
232 | * Ensure the memory we just allocated don't trigger page faults. | |
233 | * Well.. kprobes itself puts the page fault handler on the blacklist, | |
234 | * but we can never be too careful. | |
235 | */ | |
236 | wrapper_vmalloc_sync_all(); | |
237 | ||
238 | ret = register_kretprobe(<tng_krp->krp); | |
239 | if (ret) | |
240 | goto register_error; | |
241 | return 0; | |
242 | ||
243 | register_error: | |
244 | kfree(lttng_krp->krp.kp.symbol_name); | |
245 | name_error: | |
246 | kfree(lttng_krp); | |
247 | krp_error: | |
248 | kfree(event_return->desc->fields); | |
249 | kfree(event_return->desc->name); | |
250 | kfree(event_return->desc); | |
251 | event_return_error: | |
252 | kfree(event_entry->desc->fields); | |
253 | kfree(event_entry->desc->name); | |
254 | kfree(event_entry->desc); | |
255 | error: | |
256 | return ret; | |
257 | } | |
258 | EXPORT_SYMBOL_GPL(lttng_kretprobes_register); | |
259 | ||
260 | static | |
261 | void _lttng_kretprobes_unregister_release(struct kref *kref) | |
262 | { | |
263 | struct lttng_krp *lttng_krp = | |
264 | container_of(kref, struct lttng_krp, kref_register); | |
265 | unregister_kretprobe(<tng_krp->krp); | |
266 | } | |
267 | ||
a90917c3 | 268 | void lttng_kretprobes_unregister(struct lttng_event *event) |
7371f44c MD |
269 | { |
270 | kref_put(&event->u.kretprobe.lttng_krp->kref_register, | |
271 | _lttng_kretprobes_unregister_release); | |
272 | } | |
273 | EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister); | |
274 | ||
275 | static | |
276 | void _lttng_kretprobes_release(struct kref *kref) | |
277 | { | |
278 | struct lttng_krp *lttng_krp = | |
279 | container_of(kref, struct lttng_krp, kref_alloc); | |
280 | kfree(lttng_krp->krp.kp.symbol_name); | |
281 | } | |
282 | ||
a90917c3 | 283 | void lttng_kretprobes_destroy_private(struct lttng_event *event) |
7371f44c MD |
284 | { |
285 | kfree(event->desc->fields); | |
286 | kfree(event->desc->name); | |
287 | kfree(event->desc); | |
288 | kref_put(&event->u.kretprobe.lttng_krp->kref_alloc, | |
289 | _lttng_kretprobes_release); | |
290 | } | |
291 | EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private); | |
292 | ||
a0493bef MD |
293 | int lttng_kretprobes_event_enable_state(struct lttng_event *event, |
294 | int enable) | |
295 | { | |
296 | struct lttng_event *event_return; | |
297 | struct lttng_krp *lttng_krp; | |
298 | ||
299 | if (event->instrumentation != LTTNG_KERNEL_KRETPROBE) { | |
300 | return -EINVAL; | |
301 | } | |
302 | if (event->enabled == enable) { | |
303 | return -EBUSY; | |
304 | } | |
305 | lttng_krp = event->u.kretprobe.lttng_krp; | |
306 | event_return = lttng_krp->event[EVENT_RETURN]; | |
307 | ACCESS_ONCE(event->enabled) = enable; | |
308 | ACCESS_ONCE(event_return->enabled) = enable; | |
309 | return 0; | |
310 | } | |
311 | EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state); | |
312 | ||
7371f44c MD |
313 | MODULE_LICENSE("GPL and additional rights"); |
314 | MODULE_AUTHOR("Mathieu Desnoyers"); | |
315 | MODULE_DESCRIPTION("Linux Trace Toolkit Kretprobes Support"); | |
13ab8b0a MD |
316 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
317 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." | |
318 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) | |
319 | LTTNG_MODULES_EXTRAVERSION); |