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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; | |
a67ba386 | 29 | struct lttng_kernel_event_recorder *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); |
a67ba386 | 41 | struct lttng_kernel_event_recorder *event_recorder = |
7371f44c | 42 | lttng_krp->event[type]; |
79150a49 | 43 | struct lttng_probe_ctx lttng_probe_ctx = { |
a67ba386 | 44 | .event = event_recorder, |
ccecf3fb | 45 | .interruptible = !lttng_regs_irqs_disabled(regs), |
79150a49 | 46 | }; |
a67ba386 | 47 | struct lttng_channel *chan = event_recorder->chan; |
7371f44c MD |
48 | struct lib_ring_buffer_ctx ctx; |
49 | int ret; | |
50 | struct { | |
51 | unsigned long ip; | |
52 | unsigned long parent_ip; | |
53 | } payload; | |
54 | ||
585e5dcc | 55 | if (unlikely(!LTTNG_READ_ONCE(chan->session->active))) |
7371f44c | 56 | return 0; |
585e5dcc | 57 | if (unlikely(!LTTNG_READ_ONCE(chan->enabled))) |
7371f44c | 58 | return 0; |
a67ba386 | 59 | if (unlikely(!LTTNG_READ_ONCE(event_recorder->parent.enabled))) |
7371f44c MD |
60 | return 0; |
61 | ||
08726907 | 62 | payload.ip = (unsigned long) lttng_get_kretprobe(krpi)->kp.addr; |
7371f44c MD |
63 | payload.parent_ip = (unsigned long) krpi->ret_addr; |
64 | ||
79150a49 | 65 | lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx, sizeof(payload), |
a90917c3 | 66 | lttng_alignof(payload), -1); |
a67ba386 | 67 | ret = chan->ops->event_reserve(&ctx, event_recorder->priv->id); |
7371f44c MD |
68 | if (ret < 0) |
69 | return 0; | |
a90917c3 | 70 | lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload)); |
7371f44c MD |
71 | chan->ops->event_write(&ctx, &payload, sizeof(payload)); |
72 | chan->ops->event_commit(&ctx); | |
73 | return 0; | |
74 | } | |
75 | ||
76 | static | |
77 | int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi, | |
78 | struct pt_regs *regs) | |
79 | { | |
80 | return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY); | |
81 | } | |
82 | ||
83 | static | |
1b6cc48a MD |
84 | int lttng_kretprobes_handler_exit(struct kretprobe_instance *krpi, |
85 | struct pt_regs *regs) | |
7371f44c | 86 | { |
1b6cc48a | 87 | return _lttng_kretprobes_handler(krpi, regs, EVENT_EXIT); |
7371f44c MD |
88 | } |
89 | ||
437d5aa5 MD |
90 | static const struct lttng_kernel_type_common *event_type = |
91 | lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16); | |
92 | ||
7371f44c MD |
93 | /* |
94 | * Create event description | |
95 | */ | |
96 | static | |
a67ba386 | 97 | int lttng_create_kprobe_event(const char *name, struct lttng_kernel_event_recorder *event_recorder, |
7371f44c MD |
98 | enum lttng_kretprobe_type type) |
99 | { | |
437d5aa5 MD |
100 | const struct lttng_kernel_event_field **fieldp_array; |
101 | struct lttng_kernel_event_field *field; | |
102 | struct lttng_kernel_event_desc *desc; | |
7371f44c MD |
103 | char *alloc_name; |
104 | size_t name_len; | |
105 | const char *suffix = NULL; | |
437d5aa5 | 106 | int ret; |
7371f44c | 107 | |
437d5aa5 | 108 | desc = kzalloc(sizeof(*desc), GFP_KERNEL); |
7371f44c MD |
109 | if (!desc) |
110 | return -ENOMEM; | |
111 | name_len = strlen(name); | |
112 | switch (type) { | |
113 | case EVENT_ENTRY: | |
114 | suffix = "_entry"; | |
115 | break; | |
1b6cc48a MD |
116 | case EVENT_EXIT: |
117 | suffix = "_exit"; | |
7371f44c MD |
118 | break; |
119 | } | |
120 | name_len += strlen(suffix); | |
121 | alloc_name = kmalloc(name_len + 1, GFP_KERNEL); | |
122 | if (!alloc_name) { | |
123 | ret = -ENOMEM; | |
124 | goto error_str; | |
125 | } | |
126 | strcpy(alloc_name, name); | |
127 | strcat(alloc_name, suffix); | |
437d5aa5 | 128 | desc->event_name = alloc_name; |
7371f44c | 129 | desc->nr_fields = 2; |
437d5aa5 MD |
130 | fieldp_array = kzalloc(desc->nr_fields * sizeof(struct lttng_kernel_event_field *), GFP_KERNEL); |
131 | if (!fieldp_array) { | |
132 | ret = -ENOMEM; | |
133 | goto error_fieldp_array; | |
134 | } | |
135 | desc->fields = fieldp_array; | |
136 | ||
137 | field = kzalloc(sizeof(struct lttng_kernel_event_field), GFP_KERNEL); | |
138 | if (!field) { | |
7371f44c | 139 | ret = -ENOMEM; |
437d5aa5 | 140 | goto error_field0; |
7371f44c | 141 | } |
437d5aa5 MD |
142 | field->name = "ip"; |
143 | field->type = event_type; | |
144 | desc->fields[0] = field; | |
7371f44c | 145 | |
437d5aa5 MD |
146 | field = kzalloc(sizeof(struct lttng_kernel_event_field), GFP_KERNEL); |
147 | if (!field) { | |
148 | ret = -ENOMEM; | |
149 | goto error_field1; | |
150 | } | |
151 | field->name = "parent_ip"; | |
152 | field->type = event_type; | |
153 | desc->fields[1] = field; | |
7371f44c MD |
154 | |
155 | desc->owner = THIS_MODULE; | |
a67ba386 | 156 | event_recorder->priv->parent.desc = desc; |
7371f44c MD |
157 | |
158 | return 0; | |
159 | ||
437d5aa5 MD |
160 | error_field1: |
161 | kfree(desc->fields[0]); | |
162 | error_field0: | |
163 | kfree(fieldp_array); | |
164 | error_fieldp_array: | |
165 | kfree(desc->event_name); | |
7371f44c MD |
166 | error_str: |
167 | kfree(desc); | |
168 | return ret; | |
169 | } | |
170 | ||
171 | int lttng_kretprobes_register(const char *name, | |
172 | const char *symbol_name, | |
173 | uint64_t offset, | |
174 | uint64_t addr, | |
a67ba386 MD |
175 | struct lttng_kernel_event_recorder *event_recorder_entry, |
176 | struct lttng_kernel_event_recorder *event_recorder_exit) | |
7371f44c MD |
177 | { |
178 | int ret; | |
179 | struct lttng_krp *lttng_krp; | |
180 | ||
181 | /* Kprobes expects a NULL symbol name if unused */ | |
182 | if (symbol_name[0] == '\0') | |
183 | symbol_name = NULL; | |
184 | ||
a67ba386 | 185 | ret = lttng_create_kprobe_event(name, event_recorder_entry, EVENT_ENTRY); |
7371f44c MD |
186 | if (ret) |
187 | goto error; | |
a67ba386 | 188 | ret = lttng_create_kprobe_event(name, event_recorder_exit, EVENT_EXIT); |
7371f44c | 189 | if (ret) |
1b6cc48a | 190 | goto event_exit_error; |
7371f44c MD |
191 | lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL); |
192 | if (!lttng_krp) | |
193 | goto krp_error; | |
194 | lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry; | |
1b6cc48a | 195 | lttng_krp->krp.handler = lttng_kretprobes_handler_exit; |
7371f44c MD |
196 | if (symbol_name) { |
197 | char *alloc_symbol; | |
198 | ||
199 | alloc_symbol = kstrdup(symbol_name, GFP_KERNEL); | |
200 | if (!alloc_symbol) { | |
201 | ret = -ENOMEM; | |
202 | goto name_error; | |
203 | } | |
204 | lttng_krp->krp.kp.symbol_name = | |
205 | alloc_symbol; | |
a67ba386 | 206 | event_recorder_entry->priv->parent.u.kretprobe.symbol_name = |
7371f44c | 207 | alloc_symbol; |
a67ba386 | 208 | event_recorder_exit->priv->parent.u.kretprobe.symbol_name = |
7371f44c MD |
209 | alloc_symbol; |
210 | } | |
211 | lttng_krp->krp.kp.offset = offset; | |
b2c4e8fb | 212 | lttng_krp->krp.kp.addr = (void *) (unsigned long) addr; |
7371f44c MD |
213 | |
214 | /* Allow probe handler to find event structures */ | |
a67ba386 MD |
215 | lttng_krp->event[EVENT_ENTRY] = event_recorder_entry; |
216 | lttng_krp->event[EVENT_EXIT] = event_recorder_exit; | |
217 | event_recorder_entry->priv->parent.u.kretprobe.lttng_krp = lttng_krp; | |
218 | event_recorder_exit->priv->parent.u.kretprobe.lttng_krp = lttng_krp; | |
7371f44c MD |
219 | |
220 | /* | |
221 | * Both events must be unregistered before the kretprobe is | |
222 | * unregistered. Same for memory allocation. | |
223 | */ | |
224 | kref_init(<tng_krp->kref_alloc); | |
9c1f4643 | 225 | kref_get(<tng_krp->kref_alloc); /* inc refcount to 2, no overflow. */ |
7371f44c | 226 | kref_init(<tng_krp->kref_register); |
9c1f4643 | 227 | kref_get(<tng_krp->kref_register); /* inc refcount to 2, no overflow. */ |
7371f44c MD |
228 | |
229 | /* | |
230 | * Ensure the memory we just allocated don't trigger page faults. | |
231 | * Well.. kprobes itself puts the page fault handler on the blacklist, | |
232 | * but we can never be too careful. | |
233 | */ | |
263b6c88 | 234 | wrapper_vmalloc_sync_mappings(); |
7371f44c MD |
235 | |
236 | ret = register_kretprobe(<tng_krp->krp); | |
237 | if (ret) | |
238 | goto register_error; | |
239 | return 0; | |
240 | ||
241 | register_error: | |
242 | kfree(lttng_krp->krp.kp.symbol_name); | |
243 | name_error: | |
244 | kfree(lttng_krp); | |
245 | krp_error: | |
a67ba386 MD |
246 | kfree(event_recorder_exit->priv->parent.desc->fields[0]); |
247 | kfree(event_recorder_exit->priv->parent.desc->fields[1]); | |
248 | kfree(event_recorder_exit->priv->parent.desc->fields); | |
249 | kfree(event_recorder_exit->priv->parent.desc->event_name); | |
250 | kfree(event_recorder_exit->priv->parent.desc); | |
1b6cc48a | 251 | event_exit_error: |
a67ba386 MD |
252 | kfree(event_recorder_entry->priv->parent.desc->fields[0]); |
253 | kfree(event_recorder_entry->priv->parent.desc->fields[1]); | |
254 | kfree(event_recorder_entry->priv->parent.desc->fields); | |
255 | kfree(event_recorder_entry->priv->parent.desc->event_name); | |
256 | kfree(event_recorder_entry->priv->parent.desc); | |
7371f44c MD |
257 | error: |
258 | return ret; | |
259 | } | |
260 | EXPORT_SYMBOL_GPL(lttng_kretprobes_register); | |
261 | ||
262 | static | |
263 | void _lttng_kretprobes_unregister_release(struct kref *kref) | |
264 | { | |
265 | struct lttng_krp *lttng_krp = | |
266 | container_of(kref, struct lttng_krp, kref_register); | |
267 | unregister_kretprobe(<tng_krp->krp); | |
268 | } | |
269 | ||
a67ba386 | 270 | void lttng_kretprobes_unregister(struct lttng_kernel_event_recorder *event_recorder) |
7371f44c | 271 | { |
a67ba386 | 272 | kref_put(&event_recorder->priv->parent.u.kretprobe.lttng_krp->kref_register, |
7371f44c MD |
273 | _lttng_kretprobes_unregister_release); |
274 | } | |
275 | EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister); | |
276 | ||
277 | static | |
278 | void _lttng_kretprobes_release(struct kref *kref) | |
279 | { | |
280 | struct lttng_krp *lttng_krp = | |
281 | container_of(kref, struct lttng_krp, kref_alloc); | |
282 | kfree(lttng_krp->krp.kp.symbol_name); | |
283 | } | |
284 | ||
a67ba386 | 285 | void lttng_kretprobes_destroy_private(struct lttng_kernel_event_recorder *event_recorder) |
7371f44c | 286 | { |
a67ba386 MD |
287 | kfree(event_recorder->priv->parent.desc->fields[0]); |
288 | kfree(event_recorder->priv->parent.desc->fields[1]); | |
289 | kfree(event_recorder->priv->parent.desc->fields); | |
290 | kfree(event_recorder->priv->parent.desc->event_name); | |
291 | kfree(event_recorder->priv->parent.desc); | |
292 | kref_put(&event_recorder->priv->parent.u.kretprobe.lttng_krp->kref_alloc, | |
7371f44c MD |
293 | _lttng_kretprobes_release); |
294 | } | |
295 | EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private); | |
296 | ||
a67ba386 | 297 | int lttng_kretprobes_event_enable_state(struct lttng_kernel_event_recorder *event_recorder, |
a0493bef MD |
298 | int enable) |
299 | { | |
a67ba386 | 300 | struct lttng_kernel_event_recorder *event_recorder_exit; |
a0493bef MD |
301 | struct lttng_krp *lttng_krp; |
302 | ||
a67ba386 | 303 | if (event_recorder->priv->parent.instrumentation != LTTNG_KERNEL_ABI_KRETPROBE) { |
a0493bef MD |
304 | return -EINVAL; |
305 | } | |
a67ba386 | 306 | if (event_recorder->parent.enabled == enable) { |
a0493bef MD |
307 | return -EBUSY; |
308 | } | |
a67ba386 MD |
309 | lttng_krp = event_recorder->priv->parent.u.kretprobe.lttng_krp; |
310 | event_recorder_exit = lttng_krp->event[EVENT_EXIT]; | |
311 | WRITE_ONCE(event_recorder->parent.enabled, enable); | |
312 | WRITE_ONCE(event_recorder_exit->parent.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); |