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9f36eaed MJ |
1 | /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1) |
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> | |
11 | #include <linux/kprobes.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/kref.h> | |
156a3977 MD |
14 | #include <lttng-events.h> |
15 | #include <wrapper/ringbuffer/frontend_types.h> | |
16 | #include <wrapper/vmalloc.h> | |
17 | #include <wrapper/irqflags.h> | |
18 | #include <lttng-tracer.h> | |
7371f44c MD |
19 | |
20 | enum lttng_kretprobe_type { | |
21 | EVENT_ENTRY = 0, | |
22 | EVENT_RETURN = 1, | |
23 | }; | |
24 | ||
25 | struct lttng_krp { | |
26 | struct kretprobe krp; | |
a90917c3 | 27 | struct lttng_event *event[2]; /* ENTRY and RETURN */ |
7371f44c MD |
28 | struct kref kref_register; |
29 | struct kref kref_alloc; | |
30 | }; | |
31 | ||
32 | static | |
33 | int _lttng_kretprobes_handler(struct kretprobe_instance *krpi, | |
34 | struct pt_regs *regs, | |
35 | enum lttng_kretprobe_type type) | |
36 | { | |
37 | struct lttng_krp *lttng_krp = | |
38 | container_of(krpi->rp, struct lttng_krp, krp); | |
a90917c3 | 39 | struct lttng_event *event = |
7371f44c | 40 | lttng_krp->event[type]; |
79150a49 JD |
41 | struct lttng_probe_ctx lttng_probe_ctx = { |
42 | .event = event, | |
ccecf3fb | 43 | .interruptible = !lttng_regs_irqs_disabled(regs), |
79150a49 | 44 | }; |
a90917c3 | 45 | struct lttng_channel *chan = event->chan; |
7371f44c MD |
46 | struct lib_ring_buffer_ctx ctx; |
47 | int ret; | |
48 | struct { | |
49 | unsigned long ip; | |
50 | unsigned long parent_ip; | |
51 | } payload; | |
52 | ||
a8f2d0c7 | 53 | if (unlikely(!READ_ONCE(chan->session->active))) |
7371f44c | 54 | return 0; |
a8f2d0c7 | 55 | if (unlikely(!READ_ONCE(chan->enabled))) |
7371f44c | 56 | return 0; |
a8f2d0c7 | 57 | if (unlikely(!READ_ONCE(event->enabled))) |
7371f44c MD |
58 | return 0; |
59 | ||
60 | payload.ip = (unsigned long) krpi->rp->kp.addr; | |
61 | payload.parent_ip = (unsigned long) krpi->ret_addr; | |
62 | ||
79150a49 | 63 | lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx, sizeof(payload), |
a90917c3 | 64 | lttng_alignof(payload), -1); |
7371f44c MD |
65 | ret = chan->ops->event_reserve(&ctx, event->id); |
66 | if (ret < 0) | |
67 | return 0; | |
a90917c3 | 68 | lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload)); |
7371f44c MD |
69 | chan->ops->event_write(&ctx, &payload, sizeof(payload)); |
70 | chan->ops->event_commit(&ctx); | |
71 | return 0; | |
72 | } | |
73 | ||
74 | static | |
75 | int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi, | |
76 | struct pt_regs *regs) | |
77 | { | |
78 | return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY); | |
79 | } | |
80 | ||
81 | static | |
82 | int lttng_kretprobes_handler_return(struct kretprobe_instance *krpi, | |
83 | struct pt_regs *regs) | |
84 | { | |
85 | return _lttng_kretprobes_handler(krpi, regs, EVENT_RETURN); | |
86 | } | |
87 | ||
88 | /* | |
89 | * Create event description | |
90 | */ | |
91 | static | |
a90917c3 | 92 | int lttng_create_kprobe_event(const char *name, struct lttng_event *event, |
7371f44c MD |
93 | enum lttng_kretprobe_type type) |
94 | { | |
95 | struct lttng_event_field *fields; | |
96 | struct lttng_event_desc *desc; | |
97 | int ret; | |
98 | char *alloc_name; | |
99 | size_t name_len; | |
100 | const char *suffix = NULL; | |
101 | ||
102 | desc = kzalloc(sizeof(*event->desc), GFP_KERNEL); | |
103 | if (!desc) | |
104 | return -ENOMEM; | |
105 | name_len = strlen(name); | |
106 | switch (type) { | |
107 | case EVENT_ENTRY: | |
108 | suffix = "_entry"; | |
109 | break; | |
110 | case EVENT_RETURN: | |
111 | suffix = "_return"; | |
112 | break; | |
113 | } | |
114 | name_len += strlen(suffix); | |
115 | alloc_name = kmalloc(name_len + 1, GFP_KERNEL); | |
116 | if (!alloc_name) { | |
117 | ret = -ENOMEM; | |
118 | goto error_str; | |
119 | } | |
120 | strcpy(alloc_name, name); | |
121 | strcat(alloc_name, suffix); | |
122 | desc->name = alloc_name; | |
123 | desc->nr_fields = 2; | |
124 | desc->fields = fields = | |
125 | kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL); | |
126 | if (!desc->fields) { | |
127 | ret = -ENOMEM; | |
128 | goto error_fields; | |
129 | } | |
130 | fields[0].name = "ip"; | |
131 | fields[0].type.atype = atype_integer; | |
132 | fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT; | |
a90917c3 | 133 | fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; |
06254b0f | 134 | fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long); |
7371f44c MD |
135 | fields[0].type.u.basic.integer.reverse_byte_order = 0; |
136 | fields[0].type.u.basic.integer.base = 16; | |
137 | fields[0].type.u.basic.integer.encoding = lttng_encode_none; | |
138 | ||
139 | fields[1].name = "parent_ip"; | |
140 | fields[1].type.atype = atype_integer; | |
141 | fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT; | |
a90917c3 | 142 | fields[1].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; |
06254b0f | 143 | fields[1].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long); |
7371f44c MD |
144 | fields[1].type.u.basic.integer.reverse_byte_order = 0; |
145 | fields[1].type.u.basic.integer.base = 16; | |
146 | fields[1].type.u.basic.integer.encoding = lttng_encode_none; | |
147 | ||
148 | desc->owner = THIS_MODULE; | |
149 | event->desc = desc; | |
150 | ||
151 | return 0; | |
152 | ||
153 | error_fields: | |
154 | kfree(desc->name); | |
155 | error_str: | |
156 | kfree(desc); | |
157 | return ret; | |
158 | } | |
159 | ||
160 | int lttng_kretprobes_register(const char *name, | |
161 | const char *symbol_name, | |
162 | uint64_t offset, | |
163 | uint64_t addr, | |
a90917c3 MD |
164 | struct lttng_event *event_entry, |
165 | struct lttng_event *event_return) | |
7371f44c MD |
166 | { |
167 | int ret; | |
168 | struct lttng_krp *lttng_krp; | |
169 | ||
170 | /* Kprobes expects a NULL symbol name if unused */ | |
171 | if (symbol_name[0] == '\0') | |
172 | symbol_name = NULL; | |
173 | ||
174 | ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY); | |
175 | if (ret) | |
176 | goto error; | |
177 | ret = lttng_create_kprobe_event(name, event_return, EVENT_RETURN); | |
178 | if (ret) | |
179 | goto event_return_error; | |
180 | lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL); | |
181 | if (!lttng_krp) | |
182 | goto krp_error; | |
183 | lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry; | |
184 | lttng_krp->krp.handler = lttng_kretprobes_handler_return; | |
185 | if (symbol_name) { | |
186 | char *alloc_symbol; | |
187 | ||
188 | alloc_symbol = kstrdup(symbol_name, GFP_KERNEL); | |
189 | if (!alloc_symbol) { | |
190 | ret = -ENOMEM; | |
191 | goto name_error; | |
192 | } | |
193 | lttng_krp->krp.kp.symbol_name = | |
194 | alloc_symbol; | |
195 | event_entry->u.kretprobe.symbol_name = | |
196 | alloc_symbol; | |
197 | event_return->u.kretprobe.symbol_name = | |
198 | alloc_symbol; | |
199 | } | |
200 | lttng_krp->krp.kp.offset = offset; | |
b2c4e8fb | 201 | lttng_krp->krp.kp.addr = (void *) (unsigned long) addr; |
7371f44c MD |
202 | |
203 | /* Allow probe handler to find event structures */ | |
204 | lttng_krp->event[EVENT_ENTRY] = event_entry; | |
205 | lttng_krp->event[EVENT_RETURN] = event_return; | |
206 | event_entry->u.kretprobe.lttng_krp = lttng_krp; | |
207 | event_return->u.kretprobe.lttng_krp = lttng_krp; | |
208 | ||
209 | /* | |
210 | * Both events must be unregistered before the kretprobe is | |
211 | * unregistered. Same for memory allocation. | |
212 | */ | |
213 | kref_init(<tng_krp->kref_alloc); | |
9c1f4643 | 214 | kref_get(<tng_krp->kref_alloc); /* inc refcount to 2, no overflow. */ |
7371f44c | 215 | kref_init(<tng_krp->kref_register); |
9c1f4643 | 216 | kref_get(<tng_krp->kref_register); /* inc refcount to 2, no overflow. */ |
7371f44c MD |
217 | |
218 | /* | |
219 | * Ensure the memory we just allocated don't trigger page faults. | |
220 | * Well.. kprobes itself puts the page fault handler on the blacklist, | |
221 | * but we can never be too careful. | |
222 | */ | |
223 | wrapper_vmalloc_sync_all(); | |
224 | ||
225 | ret = register_kretprobe(<tng_krp->krp); | |
226 | if (ret) | |
227 | goto register_error; | |
228 | return 0; | |
229 | ||
230 | register_error: | |
231 | kfree(lttng_krp->krp.kp.symbol_name); | |
232 | name_error: | |
233 | kfree(lttng_krp); | |
234 | krp_error: | |
235 | kfree(event_return->desc->fields); | |
236 | kfree(event_return->desc->name); | |
237 | kfree(event_return->desc); | |
238 | event_return_error: | |
239 | kfree(event_entry->desc->fields); | |
240 | kfree(event_entry->desc->name); | |
241 | kfree(event_entry->desc); | |
242 | error: | |
243 | return ret; | |
244 | } | |
245 | EXPORT_SYMBOL_GPL(lttng_kretprobes_register); | |
246 | ||
247 | static | |
248 | void _lttng_kretprobes_unregister_release(struct kref *kref) | |
249 | { | |
250 | struct lttng_krp *lttng_krp = | |
251 | container_of(kref, struct lttng_krp, kref_register); | |
252 | unregister_kretprobe(<tng_krp->krp); | |
253 | } | |
254 | ||
a90917c3 | 255 | void lttng_kretprobes_unregister(struct lttng_event *event) |
7371f44c MD |
256 | { |
257 | kref_put(&event->u.kretprobe.lttng_krp->kref_register, | |
258 | _lttng_kretprobes_unregister_release); | |
259 | } | |
260 | EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister); | |
261 | ||
262 | static | |
263 | void _lttng_kretprobes_release(struct kref *kref) | |
264 | { | |
265 | struct lttng_krp *lttng_krp = | |
266 | container_of(kref, struct lttng_krp, kref_alloc); | |
267 | kfree(lttng_krp->krp.kp.symbol_name); | |
268 | } | |
269 | ||
a90917c3 | 270 | void lttng_kretprobes_destroy_private(struct lttng_event *event) |
7371f44c MD |
271 | { |
272 | kfree(event->desc->fields); | |
273 | kfree(event->desc->name); | |
274 | kfree(event->desc); | |
275 | kref_put(&event->u.kretprobe.lttng_krp->kref_alloc, | |
276 | _lttng_kretprobes_release); | |
277 | } | |
278 | EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private); | |
279 | ||
a0493bef MD |
280 | int lttng_kretprobes_event_enable_state(struct lttng_event *event, |
281 | int enable) | |
282 | { | |
283 | struct lttng_event *event_return; | |
284 | struct lttng_krp *lttng_krp; | |
285 | ||
286 | if (event->instrumentation != LTTNG_KERNEL_KRETPROBE) { | |
287 | return -EINVAL; | |
288 | } | |
289 | if (event->enabled == enable) { | |
290 | return -EBUSY; | |
291 | } | |
292 | lttng_krp = event->u.kretprobe.lttng_krp; | |
293 | event_return = lttng_krp->event[EVENT_RETURN]; | |
a8f2d0c7 MJ |
294 | WRITE_ONCE(event->enabled, enable); |
295 | WRITE_ONCE(event_return->enabled, enable); | |
a0493bef MD |
296 | return 0; |
297 | } | |
298 | EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state); | |
299 | ||
7371f44c | 300 | MODULE_LICENSE("GPL and additional rights"); |
1c124020 MJ |
301 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
302 | MODULE_DESCRIPTION("LTTng kretprobes probes"); | |
13ab8b0a MD |
303 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
304 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." | |
305 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) | |
306 | LTTNG_MODULES_EXTRAVERSION); |