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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 { | |
1b6cc48a MD |
22 | EVENT_ENTRY = 0, |
23 | EVENT_EXIT = 1, | |
7371f44c MD |
24 | }; |
25 | ||
26 | struct lttng_krp { | |
27 | struct kretprobe krp; | |
1b6cc48a | 28 | struct lttng_event *event[2]; /* ENTRY and EXIT */ |
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 | }; |
a90917c3 | 46 | struct lttng_channel *chan = event->chan; |
7371f44c MD |
47 | struct lib_ring_buffer_ctx ctx; |
48 | int ret; | |
49 | struct { | |
50 | unsigned long ip; | |
51 | unsigned long parent_ip; | |
52 | } payload; | |
53 | ||
585e5dcc | 54 | if (unlikely(!LTTNG_READ_ONCE(chan->session->active))) |
7371f44c | 55 | return 0; |
585e5dcc | 56 | if (unlikely(!LTTNG_READ_ONCE(chan->enabled))) |
7371f44c | 57 | return 0; |
585e5dcc | 58 | if (unlikely(!LTTNG_READ_ONCE(event->enabled))) |
7371f44c MD |
59 | return 0; |
60 | ||
08726907 | 61 | payload.ip = (unsigned long) lttng_get_kretprobe(krpi)->kp.addr; |
7371f44c MD |
62 | payload.parent_ip = (unsigned long) krpi->ret_addr; |
63 | ||
79150a49 | 64 | lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx, sizeof(payload), |
a90917c3 | 65 | lttng_alignof(payload), -1); |
7371f44c MD |
66 | ret = chan->ops->event_reserve(&ctx, event->id); |
67 | if (ret < 0) | |
68 | return 0; | |
a90917c3 | 69 | lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload)); |
7371f44c MD |
70 | chan->ops->event_write(&ctx, &payload, sizeof(payload)); |
71 | chan->ops->event_commit(&ctx); | |
72 | return 0; | |
73 | } | |
74 | ||
75 | static | |
76 | int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi, | |
77 | struct pt_regs *regs) | |
78 | { | |
79 | return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY); | |
80 | } | |
81 | ||
82 | static | |
1b6cc48a MD |
83 | int lttng_kretprobes_handler_exit(struct kretprobe_instance *krpi, |
84 | struct pt_regs *regs) | |
7371f44c | 85 | { |
1b6cc48a | 86 | return _lttng_kretprobes_handler(krpi, regs, EVENT_EXIT); |
7371f44c MD |
87 | } |
88 | ||
437d5aa5 MD |
89 | static const struct lttng_kernel_type_common *event_type = |
90 | lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16); | |
91 | ||
7371f44c MD |
92 | /* |
93 | * Create event description | |
94 | */ | |
95 | static | |
a90917c3 | 96 | int lttng_create_kprobe_event(const char *name, struct lttng_event *event, |
7371f44c MD |
97 | enum lttng_kretprobe_type type) |
98 | { | |
437d5aa5 MD |
99 | const struct lttng_kernel_event_field **fieldp_array; |
100 | struct lttng_kernel_event_field *field; | |
101 | struct lttng_kernel_event_desc *desc; | |
7371f44c MD |
102 | char *alloc_name; |
103 | size_t name_len; | |
104 | const char *suffix = NULL; | |
437d5aa5 | 105 | int ret; |
7371f44c | 106 | |
437d5aa5 | 107 | desc = kzalloc(sizeof(*desc), GFP_KERNEL); |
7371f44c MD |
108 | if (!desc) |
109 | return -ENOMEM; | |
110 | name_len = strlen(name); | |
111 | switch (type) { | |
112 | case EVENT_ENTRY: | |
113 | suffix = "_entry"; | |
114 | break; | |
1b6cc48a MD |
115 | case EVENT_EXIT: |
116 | suffix = "_exit"; | |
7371f44c MD |
117 | break; |
118 | } | |
119 | name_len += strlen(suffix); | |
120 | alloc_name = kmalloc(name_len + 1, GFP_KERNEL); | |
121 | if (!alloc_name) { | |
122 | ret = -ENOMEM; | |
123 | goto error_str; | |
124 | } | |
125 | strcpy(alloc_name, name); | |
126 | strcat(alloc_name, suffix); | |
437d5aa5 | 127 | desc->event_name = alloc_name; |
7371f44c | 128 | desc->nr_fields = 2; |
437d5aa5 MD |
129 | fieldp_array = kzalloc(desc->nr_fields * sizeof(struct lttng_kernel_event_field *), GFP_KERNEL); |
130 | if (!fieldp_array) { | |
131 | ret = -ENOMEM; | |
132 | goto error_fieldp_array; | |
133 | } | |
134 | desc->fields = fieldp_array; | |
135 | ||
136 | field = kzalloc(sizeof(struct lttng_kernel_event_field), GFP_KERNEL); | |
137 | if (!field) { | |
7371f44c | 138 | ret = -ENOMEM; |
437d5aa5 | 139 | goto error_field0; |
7371f44c | 140 | } |
437d5aa5 MD |
141 | field->name = "ip"; |
142 | field->type = event_type; | |
143 | desc->fields[0] = field; | |
7371f44c | 144 | |
437d5aa5 MD |
145 | field = kzalloc(sizeof(struct lttng_kernel_event_field), GFP_KERNEL); |
146 | if (!field) { | |
147 | ret = -ENOMEM; | |
148 | goto error_field1; | |
149 | } | |
150 | field->name = "parent_ip"; | |
151 | field->type = event_type; | |
152 | desc->fields[1] = field; | |
7371f44c MD |
153 | |
154 | desc->owner = THIS_MODULE; | |
155 | event->desc = desc; | |
156 | ||
157 | return 0; | |
158 | ||
437d5aa5 MD |
159 | error_field1: |
160 | kfree(desc->fields[0]); | |
161 | error_field0: | |
162 | kfree(fieldp_array); | |
163 | error_fieldp_array: | |
164 | kfree(desc->event_name); | |
7371f44c MD |
165 | error_str: |
166 | kfree(desc); | |
167 | return ret; | |
168 | } | |
169 | ||
170 | int lttng_kretprobes_register(const char *name, | |
171 | const char *symbol_name, | |
172 | uint64_t offset, | |
173 | uint64_t addr, | |
a90917c3 | 174 | struct lttng_event *event_entry, |
1b6cc48a | 175 | struct lttng_event *event_exit) |
7371f44c MD |
176 | { |
177 | int ret; | |
178 | struct lttng_krp *lttng_krp; | |
179 | ||
180 | /* Kprobes expects a NULL symbol name if unused */ | |
181 | if (symbol_name[0] == '\0') | |
182 | symbol_name = NULL; | |
183 | ||
184 | ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY); | |
185 | if (ret) | |
186 | goto error; | |
1b6cc48a | 187 | ret = lttng_create_kprobe_event(name, event_exit, EVENT_EXIT); |
7371f44c | 188 | if (ret) |
1b6cc48a | 189 | goto event_exit_error; |
7371f44c MD |
190 | lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL); |
191 | if (!lttng_krp) | |
192 | goto krp_error; | |
193 | lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry; | |
1b6cc48a | 194 | lttng_krp->krp.handler = lttng_kretprobes_handler_exit; |
7371f44c MD |
195 | if (symbol_name) { |
196 | char *alloc_symbol; | |
197 | ||
198 | alloc_symbol = kstrdup(symbol_name, GFP_KERNEL); | |
199 | if (!alloc_symbol) { | |
200 | ret = -ENOMEM; | |
201 | goto name_error; | |
202 | } | |
203 | lttng_krp->krp.kp.symbol_name = | |
204 | alloc_symbol; | |
205 | event_entry->u.kretprobe.symbol_name = | |
206 | alloc_symbol; | |
1b6cc48a | 207 | event_exit->u.kretprobe.symbol_name = |
7371f44c MD |
208 | alloc_symbol; |
209 | } | |
210 | lttng_krp->krp.kp.offset = offset; | |
b2c4e8fb | 211 | lttng_krp->krp.kp.addr = (void *) (unsigned long) addr; |
7371f44c MD |
212 | |
213 | /* Allow probe handler to find event structures */ | |
214 | lttng_krp->event[EVENT_ENTRY] = event_entry; | |
1b6cc48a | 215 | lttng_krp->event[EVENT_EXIT] = event_exit; |
7371f44c | 216 | event_entry->u.kretprobe.lttng_krp = lttng_krp; |
1b6cc48a | 217 | event_exit->u.kretprobe.lttng_krp = lttng_krp; |
7371f44c MD |
218 | |
219 | /* | |
220 | * Both events must be unregistered before the kretprobe is | |
221 | * unregistered. Same for memory allocation. | |
222 | */ | |
223 | kref_init(<tng_krp->kref_alloc); | |
9c1f4643 | 224 | kref_get(<tng_krp->kref_alloc); /* inc refcount to 2, no overflow. */ |
7371f44c | 225 | kref_init(<tng_krp->kref_register); |
9c1f4643 | 226 | kref_get(<tng_krp->kref_register); /* inc refcount to 2, no overflow. */ |
7371f44c MD |
227 | |
228 | /* | |
229 | * Ensure the memory we just allocated don't trigger page faults. | |
230 | * Well.. kprobes itself puts the page fault handler on the blacklist, | |
231 | * but we can never be too careful. | |
232 | */ | |
263b6c88 | 233 | wrapper_vmalloc_sync_mappings(); |
7371f44c MD |
234 | |
235 | ret = register_kretprobe(<tng_krp->krp); | |
236 | if (ret) | |
237 | goto register_error; | |
238 | return 0; | |
239 | ||
240 | register_error: | |
241 | kfree(lttng_krp->krp.kp.symbol_name); | |
242 | name_error: | |
243 | kfree(lttng_krp); | |
244 | krp_error: | |
437d5aa5 MD |
245 | kfree(event_exit->desc->fields[0]); |
246 | kfree(event_exit->desc->fields[1]); | |
1b6cc48a | 247 | kfree(event_exit->desc->fields); |
437d5aa5 | 248 | kfree(event_exit->desc->event_name); |
1b6cc48a MD |
249 | kfree(event_exit->desc); |
250 | event_exit_error: | |
437d5aa5 MD |
251 | kfree(event_entry->desc->fields[0]); |
252 | kfree(event_entry->desc->fields[1]); | |
7371f44c | 253 | kfree(event_entry->desc->fields); |
437d5aa5 | 254 | kfree(event_entry->desc->event_name); |
7371f44c MD |
255 | kfree(event_entry->desc); |
256 | error: | |
257 | return ret; | |
258 | } | |
259 | EXPORT_SYMBOL_GPL(lttng_kretprobes_register); | |
260 | ||
261 | static | |
262 | void _lttng_kretprobes_unregister_release(struct kref *kref) | |
263 | { | |
264 | struct lttng_krp *lttng_krp = | |
265 | container_of(kref, struct lttng_krp, kref_register); | |
266 | unregister_kretprobe(<tng_krp->krp); | |
267 | } | |
268 | ||
a90917c3 | 269 | void lttng_kretprobes_unregister(struct lttng_event *event) |
7371f44c MD |
270 | { |
271 | kref_put(&event->u.kretprobe.lttng_krp->kref_register, | |
272 | _lttng_kretprobes_unregister_release); | |
273 | } | |
274 | EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister); | |
275 | ||
276 | static | |
277 | void _lttng_kretprobes_release(struct kref *kref) | |
278 | { | |
279 | struct lttng_krp *lttng_krp = | |
280 | container_of(kref, struct lttng_krp, kref_alloc); | |
281 | kfree(lttng_krp->krp.kp.symbol_name); | |
282 | } | |
283 | ||
a90917c3 | 284 | void lttng_kretprobes_destroy_private(struct lttng_event *event) |
7371f44c | 285 | { |
437d5aa5 MD |
286 | kfree(event->desc->fields[0]); |
287 | kfree(event->desc->fields[1]); | |
7371f44c | 288 | kfree(event->desc->fields); |
437d5aa5 | 289 | kfree(event->desc->event_name); |
7371f44c MD |
290 | kfree(event->desc); |
291 | kref_put(&event->u.kretprobe.lttng_krp->kref_alloc, | |
292 | _lttng_kretprobes_release); | |
293 | } | |
294 | EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private); | |
295 | ||
a0493bef MD |
296 | int lttng_kretprobes_event_enable_state(struct lttng_event *event, |
297 | int enable) | |
298 | { | |
1b6cc48a | 299 | struct lttng_event *event_exit; |
a0493bef MD |
300 | struct lttng_krp *lttng_krp; |
301 | ||
606828e4 | 302 | if (event->instrumentation != LTTNG_KERNEL_ABI_KRETPROBE) { |
a0493bef MD |
303 | return -EINVAL; |
304 | } | |
305 | if (event->enabled == enable) { | |
306 | return -EBUSY; | |
307 | } | |
308 | lttng_krp = event->u.kretprobe.lttng_krp; | |
1b6cc48a | 309 | event_exit = lttng_krp->event[EVENT_EXIT]; |
a8f2d0c7 | 310 | WRITE_ONCE(event->enabled, enable); |
1b6cc48a | 311 | WRITE_ONCE(event_exit->enabled, enable); |
a0493bef MD |
312 | return 0; |
313 | } | |
314 | EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state); | |
315 | ||
7371f44c | 316 | MODULE_LICENSE("GPL and additional rights"); |
1c124020 MJ |
317 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
318 | MODULE_DESCRIPTION("LTTng kretprobes probes"); | |
13ab8b0a MD |
319 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
320 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." | |
321 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) | |
322 | LTTNG_MODULES_EXTRAVERSION); |