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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> |
a67ba386 | 15 | #include <lttng/events-internal.h> |
24591303 | 16 | #include <ringbuffer/frontend_types.h> |
156a3977 MD |
17 | #include <wrapper/vmalloc.h> |
18 | #include <wrapper/irqflags.h> | |
2df37e95 | 19 | #include <lttng/tracer.h> |
caa068b5 | 20 | #include <blacklist/kprobes.h> |
7371f44c MD |
21 | |
22 | enum lttng_kretprobe_type { | |
1b6cc48a MD |
23 | EVENT_ENTRY = 0, |
24 | EVENT_EXIT = 1, | |
7371f44c MD |
25 | }; |
26 | ||
27 | struct lttng_krp { | |
28 | struct kretprobe krp; | |
e2d5dbc7 | 29 | struct lttng_kernel_event_common *event[2]; /* ENTRY and EXIT */ |
7371f44c MD |
30 | struct kref kref_register; |
31 | struct kref kref_alloc; | |
32 | }; | |
33 | ||
34 | static | |
35 | int _lttng_kretprobes_handler(struct kretprobe_instance *krpi, | |
36 | struct pt_regs *regs, | |
37 | enum lttng_kretprobe_type type) | |
38 | { | |
39 | struct lttng_krp *lttng_krp = | |
08726907 | 40 | container_of(lttng_get_kretprobe(krpi), struct lttng_krp, krp); |
e2d5dbc7 | 41 | struct lttng_kernel_event_common *event = lttng_krp->event[type]; |
a92e844e | 42 | struct lttng_kernel_probe_ctx lttng_probe_ctx = { |
e2d5dbc7 | 43 | .event = event, |
ccecf3fb | 44 | .interruptible = !lttng_regs_irqs_disabled(regs), |
79150a49 | 45 | }; |
7371f44c MD |
46 | struct { |
47 | unsigned long ip; | |
48 | unsigned long parent_ip; | |
49 | } payload; | |
50 | ||
e2d5dbc7 MD |
51 | switch (event->type) { |
52 | case LTTNG_KERNEL_EVENT_TYPE_RECORDER: | |
53 | { | |
54 | struct lttng_kernel_event_recorder *event_recorder = | |
55 | container_of(event, struct lttng_kernel_event_recorder, parent); | |
56 | struct lttng_channel *chan = event_recorder->chan; | |
57 | ||
58 | if (unlikely(!LTTNG_READ_ONCE(chan->session->active))) | |
59 | return 0; | |
60 | if (unlikely(!LTTNG_READ_ONCE(chan->enabled))) | |
61 | return 0; | |
62 | break; | |
63 | } | |
64 | case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER: /* Fall-through. */ | |
65 | default: | |
66 | WARN_ON_ONCE(1); | |
67 | } | |
7371f44c | 68 | |
e2d5dbc7 | 69 | if (unlikely(!LTTNG_READ_ONCE(event->enabled))) |
7371f44c | 70 | return 0; |
e2d5dbc7 MD |
71 | |
72 | switch (event->type) { | |
73 | case LTTNG_KERNEL_EVENT_TYPE_RECORDER: | |
74 | { | |
75 | struct lttng_kernel_event_recorder *event_recorder = | |
76 | container_of(event, struct lttng_kernel_event_recorder, parent); | |
77 | struct lttng_channel *chan = event_recorder->chan; | |
78 | struct lib_ring_buffer_ctx ctx; | |
79 | int ret; | |
80 | ||
81 | payload.ip = (unsigned long) lttng_get_kretprobe(krpi)->kp.addr; | |
82 | payload.parent_ip = (unsigned long) krpi->ret_addr; | |
83 | ||
b1199bd3 MD |
84 | lib_ring_buffer_ctx_init(&ctx, event_recorder, sizeof(payload), |
85 | lttng_alignof(payload), <tng_probe_ctx); | |
c2fb9c1c | 86 | ret = chan->ops->event_reserve(&ctx); |
e2d5dbc7 MD |
87 | if (ret < 0) |
88 | return 0; | |
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); | |
92 | break; | |
93 | } | |
94 | case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER: /* Fall-through. */ | |
95 | default: | |
96 | WARN_ON_ONCE(1); | |
97 | } | |
7371f44c MD |
98 | return 0; |
99 | } | |
100 | ||
101 | static | |
102 | int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi, | |
103 | struct pt_regs *regs) | |
104 | { | |
105 | return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY); | |
106 | } | |
107 | ||
108 | static | |
1b6cc48a MD |
109 | int lttng_kretprobes_handler_exit(struct kretprobe_instance *krpi, |
110 | struct pt_regs *regs) | |
7371f44c | 111 | { |
1b6cc48a | 112 | return _lttng_kretprobes_handler(krpi, regs, EVENT_EXIT); |
7371f44c MD |
113 | } |
114 | ||
437d5aa5 MD |
115 | static const struct lttng_kernel_type_common *event_type = |
116 | lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16); | |
117 | ||
7371f44c MD |
118 | /* |
119 | * Create event description | |
120 | */ | |
121 | static | |
a67ba386 | 122 | int lttng_create_kprobe_event(const char *name, struct lttng_kernel_event_recorder *event_recorder, |
7371f44c MD |
123 | enum lttng_kretprobe_type type) |
124 | { | |
437d5aa5 MD |
125 | const struct lttng_kernel_event_field **fieldp_array; |
126 | struct lttng_kernel_event_field *field; | |
127 | struct lttng_kernel_event_desc *desc; | |
7371f44c MD |
128 | char *alloc_name; |
129 | size_t name_len; | |
130 | const char *suffix = NULL; | |
437d5aa5 | 131 | int ret; |
7371f44c | 132 | |
437d5aa5 | 133 | desc = kzalloc(sizeof(*desc), GFP_KERNEL); |
7371f44c MD |
134 | if (!desc) |
135 | return -ENOMEM; | |
136 | name_len = strlen(name); | |
137 | switch (type) { | |
138 | case EVENT_ENTRY: | |
139 | suffix = "_entry"; | |
140 | break; | |
1b6cc48a MD |
141 | case EVENT_EXIT: |
142 | suffix = "_exit"; | |
7371f44c MD |
143 | break; |
144 | } | |
145 | name_len += strlen(suffix); | |
146 | alloc_name = kmalloc(name_len + 1, GFP_KERNEL); | |
147 | if (!alloc_name) { | |
148 | ret = -ENOMEM; | |
149 | goto error_str; | |
150 | } | |
151 | strcpy(alloc_name, name); | |
152 | strcat(alloc_name, suffix); | |
437d5aa5 | 153 | desc->event_name = alloc_name; |
7371f44c | 154 | desc->nr_fields = 2; |
437d5aa5 MD |
155 | fieldp_array = kzalloc(desc->nr_fields * sizeof(struct lttng_kernel_event_field *), GFP_KERNEL); |
156 | if (!fieldp_array) { | |
157 | ret = -ENOMEM; | |
158 | goto error_fieldp_array; | |
159 | } | |
160 | desc->fields = fieldp_array; | |
161 | ||
162 | field = kzalloc(sizeof(struct lttng_kernel_event_field), GFP_KERNEL); | |
163 | if (!field) { | |
7371f44c | 164 | ret = -ENOMEM; |
437d5aa5 | 165 | goto error_field0; |
7371f44c | 166 | } |
437d5aa5 MD |
167 | field->name = "ip"; |
168 | field->type = event_type; | |
169 | desc->fields[0] = field; | |
7371f44c | 170 | |
437d5aa5 MD |
171 | field = kzalloc(sizeof(struct lttng_kernel_event_field), GFP_KERNEL); |
172 | if (!field) { | |
173 | ret = -ENOMEM; | |
174 | goto error_field1; | |
175 | } | |
176 | field->name = "parent_ip"; | |
177 | field->type = event_type; | |
178 | desc->fields[1] = field; | |
7371f44c MD |
179 | |
180 | desc->owner = THIS_MODULE; | |
a67ba386 | 181 | event_recorder->priv->parent.desc = desc; |
7371f44c MD |
182 | |
183 | return 0; | |
184 | ||
437d5aa5 MD |
185 | error_field1: |
186 | kfree(desc->fields[0]); | |
187 | error_field0: | |
188 | kfree(fieldp_array); | |
189 | error_fieldp_array: | |
190 | kfree(desc->event_name); | |
7371f44c MD |
191 | error_str: |
192 | kfree(desc); | |
193 | return ret; | |
194 | } | |
195 | ||
196 | int lttng_kretprobes_register(const char *name, | |
197 | const char *symbol_name, | |
198 | uint64_t offset, | |
199 | uint64_t addr, | |
a67ba386 MD |
200 | struct lttng_kernel_event_recorder *event_recorder_entry, |
201 | struct lttng_kernel_event_recorder *event_recorder_exit) | |
7371f44c MD |
202 | { |
203 | int ret; | |
204 | struct lttng_krp *lttng_krp; | |
205 | ||
206 | /* Kprobes expects a NULL symbol name if unused */ | |
207 | if (symbol_name[0] == '\0') | |
208 | symbol_name = NULL; | |
209 | ||
a67ba386 | 210 | ret = lttng_create_kprobe_event(name, event_recorder_entry, EVENT_ENTRY); |
7371f44c MD |
211 | if (ret) |
212 | goto error; | |
a67ba386 | 213 | ret = lttng_create_kprobe_event(name, event_recorder_exit, EVENT_EXIT); |
7371f44c | 214 | if (ret) |
1b6cc48a | 215 | goto event_exit_error; |
7371f44c MD |
216 | lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL); |
217 | if (!lttng_krp) | |
218 | goto krp_error; | |
219 | lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry; | |
1b6cc48a | 220 | lttng_krp->krp.handler = lttng_kretprobes_handler_exit; |
7371f44c MD |
221 | if (symbol_name) { |
222 | char *alloc_symbol; | |
223 | ||
224 | alloc_symbol = kstrdup(symbol_name, GFP_KERNEL); | |
225 | if (!alloc_symbol) { | |
226 | ret = -ENOMEM; | |
227 | goto name_error; | |
228 | } | |
229 | lttng_krp->krp.kp.symbol_name = | |
230 | alloc_symbol; | |
a67ba386 | 231 | event_recorder_entry->priv->parent.u.kretprobe.symbol_name = |
7371f44c | 232 | alloc_symbol; |
a67ba386 | 233 | event_recorder_exit->priv->parent.u.kretprobe.symbol_name = |
7371f44c MD |
234 | alloc_symbol; |
235 | } | |
236 | lttng_krp->krp.kp.offset = offset; | |
b2c4e8fb | 237 | lttng_krp->krp.kp.addr = (void *) (unsigned long) addr; |
7371f44c MD |
238 | |
239 | /* Allow probe handler to find event structures */ | |
e2d5dbc7 MD |
240 | lttng_krp->event[EVENT_ENTRY] = &event_recorder_entry->parent; |
241 | lttng_krp->event[EVENT_EXIT] = &event_recorder_exit->parent; | |
a67ba386 MD |
242 | event_recorder_entry->priv->parent.u.kretprobe.lttng_krp = lttng_krp; |
243 | event_recorder_exit->priv->parent.u.kretprobe.lttng_krp = lttng_krp; | |
7371f44c MD |
244 | |
245 | /* | |
246 | * Both events must be unregistered before the kretprobe is | |
247 | * unregistered. Same for memory allocation. | |
248 | */ | |
249 | kref_init(<tng_krp->kref_alloc); | |
9c1f4643 | 250 | kref_get(<tng_krp->kref_alloc); /* inc refcount to 2, no overflow. */ |
7371f44c | 251 | kref_init(<tng_krp->kref_register); |
9c1f4643 | 252 | kref_get(<tng_krp->kref_register); /* inc refcount to 2, no overflow. */ |
7371f44c MD |
253 | |
254 | /* | |
255 | * Ensure the memory we just allocated don't trigger page faults. | |
256 | * Well.. kprobes itself puts the page fault handler on the blacklist, | |
257 | * but we can never be too careful. | |
258 | */ | |
263b6c88 | 259 | wrapper_vmalloc_sync_mappings(); |
7371f44c MD |
260 | |
261 | ret = register_kretprobe(<tng_krp->krp); | |
262 | if (ret) | |
263 | goto register_error; | |
264 | return 0; | |
265 | ||
266 | register_error: | |
267 | kfree(lttng_krp->krp.kp.symbol_name); | |
268 | name_error: | |
269 | kfree(lttng_krp); | |
270 | krp_error: | |
a67ba386 MD |
271 | kfree(event_recorder_exit->priv->parent.desc->fields[0]); |
272 | kfree(event_recorder_exit->priv->parent.desc->fields[1]); | |
273 | kfree(event_recorder_exit->priv->parent.desc->fields); | |
274 | kfree(event_recorder_exit->priv->parent.desc->event_name); | |
275 | kfree(event_recorder_exit->priv->parent.desc); | |
1b6cc48a | 276 | event_exit_error: |
a67ba386 MD |
277 | kfree(event_recorder_entry->priv->parent.desc->fields[0]); |
278 | kfree(event_recorder_entry->priv->parent.desc->fields[1]); | |
279 | kfree(event_recorder_entry->priv->parent.desc->fields); | |
280 | kfree(event_recorder_entry->priv->parent.desc->event_name); | |
281 | kfree(event_recorder_entry->priv->parent.desc); | |
7371f44c MD |
282 | error: |
283 | return ret; | |
284 | } | |
285 | EXPORT_SYMBOL_GPL(lttng_kretprobes_register); | |
286 | ||
287 | static | |
288 | void _lttng_kretprobes_unregister_release(struct kref *kref) | |
289 | { | |
290 | struct lttng_krp *lttng_krp = | |
291 | container_of(kref, struct lttng_krp, kref_register); | |
292 | unregister_kretprobe(<tng_krp->krp); | |
293 | } | |
294 | ||
a67ba386 | 295 | void lttng_kretprobes_unregister(struct lttng_kernel_event_recorder *event_recorder) |
7371f44c | 296 | { |
a67ba386 | 297 | kref_put(&event_recorder->priv->parent.u.kretprobe.lttng_krp->kref_register, |
7371f44c MD |
298 | _lttng_kretprobes_unregister_release); |
299 | } | |
300 | EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister); | |
301 | ||
302 | static | |
303 | void _lttng_kretprobes_release(struct kref *kref) | |
304 | { | |
305 | struct lttng_krp *lttng_krp = | |
306 | container_of(kref, struct lttng_krp, kref_alloc); | |
307 | kfree(lttng_krp->krp.kp.symbol_name); | |
308 | } | |
309 | ||
a67ba386 | 310 | void lttng_kretprobes_destroy_private(struct lttng_kernel_event_recorder *event_recorder) |
7371f44c | 311 | { |
a67ba386 MD |
312 | kfree(event_recorder->priv->parent.desc->fields[0]); |
313 | kfree(event_recorder->priv->parent.desc->fields[1]); | |
314 | kfree(event_recorder->priv->parent.desc->fields); | |
315 | kfree(event_recorder->priv->parent.desc->event_name); | |
316 | kfree(event_recorder->priv->parent.desc); | |
317 | kref_put(&event_recorder->priv->parent.u.kretprobe.lttng_krp->kref_alloc, | |
7371f44c MD |
318 | _lttng_kretprobes_release); |
319 | } | |
320 | EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private); | |
321 | ||
e2d5dbc7 | 322 | int lttng_kretprobes_event_enable_state(struct lttng_kernel_event_common *event, |
a0493bef MD |
323 | int enable) |
324 | { | |
e2d5dbc7 | 325 | struct lttng_kernel_event_common *event_exit; |
a0493bef MD |
326 | struct lttng_krp *lttng_krp; |
327 | ||
e2d5dbc7 | 328 | if (event->priv->instrumentation != LTTNG_KERNEL_ABI_KRETPROBE) { |
a0493bef MD |
329 | return -EINVAL; |
330 | } | |
e2d5dbc7 | 331 | if (event->enabled == enable) { |
a0493bef MD |
332 | return -EBUSY; |
333 | } | |
e2d5dbc7 MD |
334 | lttng_krp = event->priv->u.kretprobe.lttng_krp; |
335 | event_exit = lttng_krp->event[EVENT_EXIT]; | |
336 | WRITE_ONCE(event->enabled, enable); | |
337 | WRITE_ONCE(event_exit->enabled, enable); | |
a0493bef MD |
338 | return 0; |
339 | } | |
340 | EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state); | |
341 | ||
7371f44c | 342 | MODULE_LICENSE("GPL and additional rights"); |
1c124020 MJ |
343 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
344 | MODULE_DESCRIPTION("LTTng kretprobes probes"); | |
13ab8b0a MD |
345 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
346 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." | |
347 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) | |
348 | LTTNG_MODULES_EXTRAVERSION); |