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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]; |
346cb5ee | 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); | |
ac847066 | 56 | struct lttng_kernel_channel_buffer *chan = event_recorder->chan; |
e2d5dbc7 | 57 | |
ac847066 | 58 | if (unlikely(!LTTNG_READ_ONCE(chan->parent.session->active))) |
e2d5dbc7 | 59 | return 0; |
ac847066 | 60 | if (unlikely(!LTTNG_READ_ONCE(chan->parent.enabled))) |
e2d5dbc7 MD |
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); | |
ac847066 | 77 | struct lttng_kernel_channel_buffer *chan = event_recorder->chan; |
e27e4381 | 78 | struct lttng_kernel_ring_buffer_ctx ctx; |
e2d5dbc7 MD |
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 | ||
c7d9db61 MD |
84 | lib_ring_buffer_ctx_init(&ctx, event_recorder, sizeof(payload), |
85 | lttng_alignof(payload), <tng_probe_ctx); | |
cefd899f | 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 | ||
e69abdfd MD |
115 | static const struct lttng_kernel_event_field *event_fields[] = { |
116 | lttng_kernel_static_event_field("ip", | |
117 | lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16), | |
118 | false, false, false), | |
119 | lttng_kernel_static_event_field("parent_ip", | |
120 | lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16), | |
121 | false, false, false), | |
122 | }; | |
123 | ||
124 | static const struct lttng_kernel_tracepoint_class tp_class = { | |
125 | .nr_fields = ARRAY_SIZE(event_fields), | |
126 | .fields = event_fields, | |
127 | }; | |
437d5aa5 | 128 | |
7371f44c MD |
129 | /* |
130 | * Create event description | |
131 | */ | |
132 | static | |
a67ba386 | 133 | int lttng_create_kprobe_event(const char *name, struct lttng_kernel_event_recorder *event_recorder, |
7371f44c MD |
134 | enum lttng_kretprobe_type type) |
135 | { | |
437d5aa5 | 136 | struct lttng_kernel_event_desc *desc; |
7371f44c MD |
137 | char *alloc_name; |
138 | size_t name_len; | |
139 | const char *suffix = NULL; | |
437d5aa5 | 140 | int ret; |
7371f44c | 141 | |
437d5aa5 | 142 | desc = kzalloc(sizeof(*desc), GFP_KERNEL); |
7371f44c MD |
143 | if (!desc) |
144 | return -ENOMEM; | |
145 | name_len = strlen(name); | |
146 | switch (type) { | |
147 | case EVENT_ENTRY: | |
148 | suffix = "_entry"; | |
149 | break; | |
1b6cc48a MD |
150 | case EVENT_EXIT: |
151 | suffix = "_exit"; | |
7371f44c MD |
152 | break; |
153 | } | |
154 | name_len += strlen(suffix); | |
155 | alloc_name = kmalloc(name_len + 1, GFP_KERNEL); | |
156 | if (!alloc_name) { | |
157 | ret = -ENOMEM; | |
158 | goto error_str; | |
159 | } | |
160 | strcpy(alloc_name, name); | |
161 | strcat(alloc_name, suffix); | |
437d5aa5 | 162 | desc->event_name = alloc_name; |
e69abdfd | 163 | desc->tp_class = &tp_class; |
7371f44c | 164 | desc->owner = THIS_MODULE; |
a67ba386 | 165 | event_recorder->priv->parent.desc = desc; |
7371f44c MD |
166 | |
167 | return 0; | |
168 | ||
7371f44c MD |
169 | error_str: |
170 | kfree(desc); | |
171 | return ret; | |
172 | } | |
173 | ||
174 | int lttng_kretprobes_register(const char *name, | |
175 | const char *symbol_name, | |
176 | uint64_t offset, | |
177 | uint64_t addr, | |
a67ba386 MD |
178 | struct lttng_kernel_event_recorder *event_recorder_entry, |
179 | struct lttng_kernel_event_recorder *event_recorder_exit) | |
7371f44c MD |
180 | { |
181 | int ret; | |
182 | struct lttng_krp *lttng_krp; | |
183 | ||
184 | /* Kprobes expects a NULL symbol name if unused */ | |
185 | if (symbol_name[0] == '\0') | |
186 | symbol_name = NULL; | |
187 | ||
a67ba386 | 188 | ret = lttng_create_kprobe_event(name, event_recorder_entry, EVENT_ENTRY); |
7371f44c MD |
189 | if (ret) |
190 | goto error; | |
a67ba386 | 191 | ret = lttng_create_kprobe_event(name, event_recorder_exit, EVENT_EXIT); |
7371f44c | 192 | if (ret) |
1b6cc48a | 193 | goto event_exit_error; |
7371f44c MD |
194 | lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL); |
195 | if (!lttng_krp) | |
196 | goto krp_error; | |
197 | lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry; | |
1b6cc48a | 198 | lttng_krp->krp.handler = lttng_kretprobes_handler_exit; |
7371f44c MD |
199 | if (symbol_name) { |
200 | char *alloc_symbol; | |
201 | ||
202 | alloc_symbol = kstrdup(symbol_name, GFP_KERNEL); | |
203 | if (!alloc_symbol) { | |
204 | ret = -ENOMEM; | |
205 | goto name_error; | |
206 | } | |
207 | lttng_krp->krp.kp.symbol_name = | |
208 | alloc_symbol; | |
a67ba386 | 209 | event_recorder_entry->priv->parent.u.kretprobe.symbol_name = |
7371f44c | 210 | alloc_symbol; |
a67ba386 | 211 | event_recorder_exit->priv->parent.u.kretprobe.symbol_name = |
7371f44c MD |
212 | alloc_symbol; |
213 | } | |
214 | lttng_krp->krp.kp.offset = offset; | |
b2c4e8fb | 215 | lttng_krp->krp.kp.addr = (void *) (unsigned long) addr; |
7371f44c MD |
216 | |
217 | /* Allow probe handler to find event structures */ | |
e2d5dbc7 MD |
218 | lttng_krp->event[EVENT_ENTRY] = &event_recorder_entry->parent; |
219 | lttng_krp->event[EVENT_EXIT] = &event_recorder_exit->parent; | |
a67ba386 MD |
220 | event_recorder_entry->priv->parent.u.kretprobe.lttng_krp = lttng_krp; |
221 | event_recorder_exit->priv->parent.u.kretprobe.lttng_krp = lttng_krp; | |
7371f44c MD |
222 | |
223 | /* | |
224 | * Both events must be unregistered before the kretprobe is | |
225 | * unregistered. Same for memory allocation. | |
226 | */ | |
227 | kref_init(<tng_krp->kref_alloc); | |
9c1f4643 | 228 | kref_get(<tng_krp->kref_alloc); /* inc refcount to 2, no overflow. */ |
7371f44c | 229 | kref_init(<tng_krp->kref_register); |
9c1f4643 | 230 | kref_get(<tng_krp->kref_register); /* inc refcount to 2, no overflow. */ |
7371f44c MD |
231 | |
232 | /* | |
233 | * Ensure the memory we just allocated don't trigger page faults. | |
234 | * Well.. kprobes itself puts the page fault handler on the blacklist, | |
235 | * but we can never be too careful. | |
236 | */ | |
263b6c88 | 237 | wrapper_vmalloc_sync_mappings(); |
7371f44c MD |
238 | |
239 | ret = register_kretprobe(<tng_krp->krp); | |
240 | if (ret) | |
241 | goto register_error; | |
242 | return 0; | |
243 | ||
244 | register_error: | |
245 | kfree(lttng_krp->krp.kp.symbol_name); | |
246 | name_error: | |
247 | kfree(lttng_krp); | |
248 | krp_error: | |
a67ba386 MD |
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->event_name); |
253 | kfree(event_recorder_entry->priv->parent.desc); | |
7371f44c MD |
254 | error: |
255 | return ret; | |
256 | } | |
257 | EXPORT_SYMBOL_GPL(lttng_kretprobes_register); | |
258 | ||
259 | static | |
260 | void _lttng_kretprobes_unregister_release(struct kref *kref) | |
261 | { | |
262 | struct lttng_krp *lttng_krp = | |
263 | container_of(kref, struct lttng_krp, kref_register); | |
264 | unregister_kretprobe(<tng_krp->krp); | |
265 | } | |
266 | ||
a67ba386 | 267 | void lttng_kretprobes_unregister(struct lttng_kernel_event_recorder *event_recorder) |
7371f44c | 268 | { |
a67ba386 | 269 | kref_put(&event_recorder->priv->parent.u.kretprobe.lttng_krp->kref_register, |
7371f44c MD |
270 | _lttng_kretprobes_unregister_release); |
271 | } | |
272 | EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister); | |
273 | ||
274 | static | |
275 | void _lttng_kretprobes_release(struct kref *kref) | |
276 | { | |
277 | struct lttng_krp *lttng_krp = | |
278 | container_of(kref, struct lttng_krp, kref_alloc); | |
279 | kfree(lttng_krp->krp.kp.symbol_name); | |
280 | } | |
281 | ||
a67ba386 | 282 | void lttng_kretprobes_destroy_private(struct lttng_kernel_event_recorder *event_recorder) |
7371f44c | 283 | { |
a67ba386 MD |
284 | kfree(event_recorder->priv->parent.desc->event_name); |
285 | kfree(event_recorder->priv->parent.desc); | |
286 | kref_put(&event_recorder->priv->parent.u.kretprobe.lttng_krp->kref_alloc, | |
7371f44c MD |
287 | _lttng_kretprobes_release); |
288 | } | |
289 | EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private); | |
290 | ||
e2d5dbc7 | 291 | int lttng_kretprobes_event_enable_state(struct lttng_kernel_event_common *event, |
a0493bef MD |
292 | int enable) |
293 | { | |
e2d5dbc7 | 294 | struct lttng_kernel_event_common *event_exit; |
a0493bef MD |
295 | struct lttng_krp *lttng_krp; |
296 | ||
e2d5dbc7 | 297 | if (event->priv->instrumentation != LTTNG_KERNEL_ABI_KRETPROBE) { |
a0493bef MD |
298 | return -EINVAL; |
299 | } | |
e2d5dbc7 | 300 | if (event->enabled == enable) { |
a0493bef MD |
301 | return -EBUSY; |
302 | } | |
e2d5dbc7 MD |
303 | lttng_krp = event->priv->u.kretprobe.lttng_krp; |
304 | event_exit = lttng_krp->event[EVENT_EXIT]; | |
305 | WRITE_ONCE(event->enabled, enable); | |
306 | WRITE_ONCE(event_exit->enabled, enable); | |
a0493bef MD |
307 | return 0; |
308 | } | |
309 | EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state); | |
310 | ||
7371f44c | 311 | MODULE_LICENSE("GPL and additional rights"); |
1c124020 MJ |
312 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
313 | MODULE_DESCRIPTION("LTTng kretprobes probes"); | |
13ab8b0a MD |
314 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
315 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." | |
316 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) | |
317 | LTTNG_MODULES_EXTRAVERSION); |