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b7cdc182 | 1 | /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) |
9f36eaed MJ |
2 | * |
3 | * probes/lttng-kretprobes.c | |
7371f44c MD |
4 | * |
5 | * LTTng kretprobes integration module. | |
6 | * | |
886d51a3 | 7 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
7371f44c MD |
8 | */ |
9 | ||
10 | #include <linux/module.h> | |
08726907 | 11 | #include <wrapper/kprobes.h> |
7371f44c MD |
12 | #include <linux/slab.h> |
13 | #include <linux/kref.h> | |
2df37e95 | 14 | #include <lttng/events.h> |
24591303 | 15 | #include <ringbuffer/frontend_types.h> |
156a3977 MD |
16 | #include <wrapper/vmalloc.h> |
17 | #include <wrapper/irqflags.h> | |
2df37e95 | 18 | #include <lttng/tracer.h> |
caa068b5 | 19 | #include <blacklist/kprobes.h> |
7371f44c MD |
20 | |
21 | enum lttng_kretprobe_type { | |
22 | EVENT_ENTRY = 0, | |
23 | EVENT_RETURN = 1, | |
24 | }; | |
25 | ||
26 | struct lttng_krp { | |
27 | struct kretprobe krp; | |
a90917c3 | 28 | struct lttng_event *event[2]; /* ENTRY and RETURN */ |
7371f44c MD |
29 | struct kref kref_register; |
30 | struct kref kref_alloc; | |
31 | }; | |
32 | ||
33 | static | |
34 | int _lttng_kretprobes_handler(struct kretprobe_instance *krpi, | |
35 | struct pt_regs *regs, | |
36 | enum lttng_kretprobe_type type) | |
37 | { | |
38 | struct lttng_krp *lttng_krp = | |
08726907 | 39 | container_of(lttng_get_kretprobe(krpi), struct lttng_krp, krp); |
a90917c3 | 40 | struct lttng_event *event = |
7371f44c | 41 | lttng_krp->event[type]; |
79150a49 JD |
42 | struct lttng_probe_ctx lttng_probe_ctx = { |
43 | .event = event, | |
ccecf3fb | 44 | .interruptible = !lttng_regs_irqs_disabled(regs), |
79150a49 | 45 | }; |
0c023c01 | 46 | struct lttng_event_container *container = event->container; |
7371f44c MD |
47 | int ret; |
48 | struct { | |
49 | unsigned long ip; | |
50 | unsigned long parent_ip; | |
51 | } payload; | |
52 | ||
0c023c01 | 53 | if (unlikely(!LTTNG_READ_ONCE(container->session->active))) |
7371f44c | 54 | return 0; |
0c023c01 | 55 | if (unlikely(!LTTNG_READ_ONCE(container->enabled))) |
7371f44c | 56 | return 0; |
585e5dcc | 57 | if (unlikely(!LTTNG_READ_ONCE(event->enabled))) |
7371f44c MD |
58 | return 0; |
59 | ||
0c023c01 MD |
60 | switch (container->type) { |
61 | case LTTNG_EVENT_CONTAINER_CHANNEL: | |
62 | { | |
63 | struct lttng_channel *chan = lttng_event_container_get_channel(container); | |
64 | struct lib_ring_buffer_ctx ctx; | |
7371f44c | 65 | |
0c023c01 MD |
66 | payload.ip = (unsigned long) lttng_get_kretprobe(krpi)->kp.addr; |
67 | payload.parent_ip = (unsigned long) krpi->ret_addr; | |
68 | ||
69 | lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx, sizeof(payload), | |
70 | lttng_alignof(payload), -1); | |
71 | ret = chan->ops->event_reserve(&ctx, event->id); | |
72 | if (ret < 0) | |
73 | return 0; | |
74 | lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload)); | |
75 | chan->ops->event_write(&ctx, &payload, sizeof(payload)); | |
76 | chan->ops->event_commit(&ctx); | |
77 | break; | |
78 | } | |
79 | case LTTNG_EVENT_CONTAINER_COUNTER: | |
80 | { | |
81 | struct lttng_counter *counter = lttng_event_container_get_counter(container); | |
82 | size_t index = event->id; | |
83 | ||
84 | (void) counter->ops->counter_add(counter->counter, &index, 1); | |
85 | break; | |
86 | } | |
87 | } | |
7371f44c MD |
88 | return 0; |
89 | } | |
90 | ||
91 | static | |
92 | int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi, | |
93 | struct pt_regs *regs) | |
94 | { | |
95 | return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY); | |
96 | } | |
97 | ||
98 | static | |
99 | int lttng_kretprobes_handler_return(struct kretprobe_instance *krpi, | |
100 | struct pt_regs *regs) | |
101 | { | |
102 | return _lttng_kretprobes_handler(krpi, regs, EVENT_RETURN); | |
103 | } | |
104 | ||
105 | /* | |
106 | * Create event description | |
107 | */ | |
108 | static | |
a90917c3 | 109 | int lttng_create_kprobe_event(const char *name, struct lttng_event *event, |
7371f44c MD |
110 | enum lttng_kretprobe_type type) |
111 | { | |
112 | struct lttng_event_field *fields; | |
113 | struct lttng_event_desc *desc; | |
114 | int ret; | |
115 | char *alloc_name; | |
116 | size_t name_len; | |
117 | const char *suffix = NULL; | |
118 | ||
119 | desc = kzalloc(sizeof(*event->desc), GFP_KERNEL); | |
120 | if (!desc) | |
121 | return -ENOMEM; | |
122 | name_len = strlen(name); | |
123 | switch (type) { | |
124 | case EVENT_ENTRY: | |
125 | suffix = "_entry"; | |
126 | break; | |
127 | case EVENT_RETURN: | |
128 | suffix = "_return"; | |
129 | break; | |
130 | } | |
131 | name_len += strlen(suffix); | |
132 | alloc_name = kmalloc(name_len + 1, GFP_KERNEL); | |
133 | if (!alloc_name) { | |
134 | ret = -ENOMEM; | |
135 | goto error_str; | |
136 | } | |
137 | strcpy(alloc_name, name); | |
138 | strcat(alloc_name, suffix); | |
139 | desc->name = alloc_name; | |
140 | desc->nr_fields = 2; | |
141 | desc->fields = fields = | |
142 | kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL); | |
143 | if (!desc->fields) { | |
144 | ret = -ENOMEM; | |
145 | goto error_fields; | |
146 | } | |
147 | fields[0].name = "ip"; | |
148 | fields[0].type.atype = atype_integer; | |
ceabb767 MD |
149 | fields[0].type.u.integer.size = sizeof(unsigned long) * CHAR_BIT; |
150 | fields[0].type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; | |
151 | fields[0].type.u.integer.signedness = lttng_is_signed_type(unsigned long); | |
152 | fields[0].type.u.integer.reverse_byte_order = 0; | |
153 | fields[0].type.u.integer.base = 16; | |
154 | fields[0].type.u.integer.encoding = lttng_encode_none; | |
7371f44c MD |
155 | |
156 | fields[1].name = "parent_ip"; | |
157 | fields[1].type.atype = atype_integer; | |
ceabb767 MD |
158 | fields[1].type.u.integer.size = sizeof(unsigned long) * CHAR_BIT; |
159 | fields[1].type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; | |
160 | fields[1].type.u.integer.signedness = lttng_is_signed_type(unsigned long); | |
161 | fields[1].type.u.integer.reverse_byte_order = 0; | |
162 | fields[1].type.u.integer.base = 16; | |
163 | fields[1].type.u.integer.encoding = lttng_encode_none; | |
7371f44c MD |
164 | |
165 | desc->owner = THIS_MODULE; | |
166 | event->desc = desc; | |
167 | ||
168 | return 0; | |
169 | ||
170 | error_fields: | |
171 | kfree(desc->name); | |
172 | error_str: | |
173 | kfree(desc); | |
174 | return ret; | |
175 | } | |
176 | ||
177 | int lttng_kretprobes_register(const char *name, | |
178 | const char *symbol_name, | |
179 | uint64_t offset, | |
180 | uint64_t addr, | |
a90917c3 MD |
181 | struct lttng_event *event_entry, |
182 | struct lttng_event *event_return) | |
7371f44c MD |
183 | { |
184 | int ret; | |
185 | struct lttng_krp *lttng_krp; | |
186 | ||
187 | /* Kprobes expects a NULL symbol name if unused */ | |
188 | if (symbol_name[0] == '\0') | |
189 | symbol_name = NULL; | |
190 | ||
191 | ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY); | |
192 | if (ret) | |
193 | goto error; | |
194 | ret = lttng_create_kprobe_event(name, event_return, EVENT_RETURN); | |
195 | if (ret) | |
196 | goto event_return_error; | |
197 | lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL); | |
198 | if (!lttng_krp) | |
199 | goto krp_error; | |
200 | lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry; | |
201 | lttng_krp->krp.handler = lttng_kretprobes_handler_return; | |
202 | if (symbol_name) { | |
203 | char *alloc_symbol; | |
204 | ||
205 | alloc_symbol = kstrdup(symbol_name, GFP_KERNEL); | |
206 | if (!alloc_symbol) { | |
207 | ret = -ENOMEM; | |
208 | goto name_error; | |
209 | } | |
210 | lttng_krp->krp.kp.symbol_name = | |
211 | alloc_symbol; | |
212 | event_entry->u.kretprobe.symbol_name = | |
213 | alloc_symbol; | |
214 | event_return->u.kretprobe.symbol_name = | |
215 | alloc_symbol; | |
216 | } | |
217 | lttng_krp->krp.kp.offset = offset; | |
b2c4e8fb | 218 | lttng_krp->krp.kp.addr = (void *) (unsigned long) addr; |
7371f44c MD |
219 | |
220 | /* Allow probe handler to find event structures */ | |
221 | lttng_krp->event[EVENT_ENTRY] = event_entry; | |
222 | lttng_krp->event[EVENT_RETURN] = event_return; | |
223 | event_entry->u.kretprobe.lttng_krp = lttng_krp; | |
224 | event_return->u.kretprobe.lttng_krp = lttng_krp; | |
225 | ||
226 | /* | |
227 | * Both events must be unregistered before the kretprobe is | |
228 | * unregistered. Same for memory allocation. | |
229 | */ | |
230 | kref_init(<tng_krp->kref_alloc); | |
9c1f4643 | 231 | kref_get(<tng_krp->kref_alloc); /* inc refcount to 2, no overflow. */ |
7371f44c | 232 | kref_init(<tng_krp->kref_register); |
9c1f4643 | 233 | kref_get(<tng_krp->kref_register); /* inc refcount to 2, no overflow. */ |
7371f44c MD |
234 | |
235 | /* | |
236 | * Ensure the memory we just allocated don't trigger page faults. | |
237 | * Well.. kprobes itself puts the page fault handler on the blacklist, | |
238 | * but we can never be too careful. | |
239 | */ | |
263b6c88 | 240 | wrapper_vmalloc_sync_mappings(); |
7371f44c MD |
241 | |
242 | ret = register_kretprobe(<tng_krp->krp); | |
243 | if (ret) | |
244 | goto register_error; | |
245 | return 0; | |
246 | ||
247 | register_error: | |
248 | kfree(lttng_krp->krp.kp.symbol_name); | |
249 | name_error: | |
250 | kfree(lttng_krp); | |
251 | krp_error: | |
252 | kfree(event_return->desc->fields); | |
253 | kfree(event_return->desc->name); | |
254 | kfree(event_return->desc); | |
255 | event_return_error: | |
256 | kfree(event_entry->desc->fields); | |
257 | kfree(event_entry->desc->name); | |
258 | kfree(event_entry->desc); | |
259 | error: | |
260 | return ret; | |
261 | } | |
262 | EXPORT_SYMBOL_GPL(lttng_kretprobes_register); | |
263 | ||
264 | static | |
265 | void _lttng_kretprobes_unregister_release(struct kref *kref) | |
266 | { | |
267 | struct lttng_krp *lttng_krp = | |
268 | container_of(kref, struct lttng_krp, kref_register); | |
269 | unregister_kretprobe(<tng_krp->krp); | |
270 | } | |
271 | ||
a90917c3 | 272 | void lttng_kretprobes_unregister(struct lttng_event *event) |
7371f44c MD |
273 | { |
274 | kref_put(&event->u.kretprobe.lttng_krp->kref_register, | |
275 | _lttng_kretprobes_unregister_release); | |
276 | } | |
277 | EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister); | |
278 | ||
279 | static | |
280 | void _lttng_kretprobes_release(struct kref *kref) | |
281 | { | |
282 | struct lttng_krp *lttng_krp = | |
283 | container_of(kref, struct lttng_krp, kref_alloc); | |
284 | kfree(lttng_krp->krp.kp.symbol_name); | |
285 | } | |
286 | ||
a90917c3 | 287 | void lttng_kretprobes_destroy_private(struct lttng_event *event) |
7371f44c MD |
288 | { |
289 | kfree(event->desc->fields); | |
290 | kfree(event->desc->name); | |
291 | kfree(event->desc); | |
292 | kref_put(&event->u.kretprobe.lttng_krp->kref_alloc, | |
293 | _lttng_kretprobes_release); | |
294 | } | |
295 | EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private); | |
296 | ||
a0493bef MD |
297 | int lttng_kretprobes_event_enable_state(struct lttng_event *event, |
298 | int enable) | |
299 | { | |
300 | struct lttng_event *event_return; | |
301 | struct lttng_krp *lttng_krp; | |
302 | ||
303 | if (event->instrumentation != LTTNG_KERNEL_KRETPROBE) { | |
304 | return -EINVAL; | |
305 | } | |
306 | if (event->enabled == enable) { | |
307 | return -EBUSY; | |
308 | } | |
309 | lttng_krp = event->u.kretprobe.lttng_krp; | |
310 | event_return = lttng_krp->event[EVENT_RETURN]; | |
a8f2d0c7 MJ |
311 | WRITE_ONCE(event->enabled, enable); |
312 | WRITE_ONCE(event_return->enabled, enable); | |
a0493bef MD |
313 | return 0; |
314 | } | |
315 | EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state); | |
316 | ||
7371f44c | 317 | MODULE_LICENSE("GPL and additional rights"); |
1c124020 MJ |
318 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
319 | MODULE_DESCRIPTION("LTTng kretprobes probes"); | |
13ab8b0a MD |
320 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
321 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." | |
322 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) | |
323 | LTTNG_MODULES_EXTRAVERSION); |