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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> | |
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> | |
156a3977 MD |
16 | #include <wrapper/irqflags.h> |
17 | #include <lttng-tracer.h> | |
7371f44c MD |
18 | |
19 | enum lttng_kretprobe_type { | |
20 | EVENT_ENTRY = 0, | |
21 | EVENT_RETURN = 1, | |
22 | }; | |
23 | ||
24 | struct lttng_krp { | |
25 | struct kretprobe krp; | |
a90917c3 | 26 | struct lttng_event *event[2]; /* ENTRY and RETURN */ |
7371f44c MD |
27 | struct kref kref_register; |
28 | struct kref kref_alloc; | |
29 | }; | |
30 | ||
31 | static | |
32 | int _lttng_kretprobes_handler(struct kretprobe_instance *krpi, | |
33 | struct pt_regs *regs, | |
34 | enum lttng_kretprobe_type type) | |
35 | { | |
36 | struct lttng_krp *lttng_krp = | |
37 | container_of(krpi->rp, struct lttng_krp, krp); | |
a90917c3 | 38 | struct lttng_event *event = |
7371f44c | 39 | lttng_krp->event[type]; |
79150a49 JD |
40 | struct lttng_probe_ctx lttng_probe_ctx = { |
41 | .event = event, | |
ccecf3fb | 42 | .interruptible = !lttng_regs_irqs_disabled(regs), |
79150a49 | 43 | }; |
a90917c3 | 44 | struct lttng_channel *chan = event->chan; |
7371f44c MD |
45 | struct lib_ring_buffer_ctx ctx; |
46 | int ret; | |
47 | struct { | |
48 | unsigned long ip; | |
49 | unsigned long parent_ip; | |
50 | } payload; | |
51 | ||
a8f2d0c7 | 52 | if (unlikely(!READ_ONCE(chan->session->active))) |
7371f44c | 53 | return 0; |
a8f2d0c7 | 54 | if (unlikely(!READ_ONCE(chan->enabled))) |
7371f44c | 55 | return 0; |
a8f2d0c7 | 56 | if (unlikely(!READ_ONCE(event->enabled))) |
7371f44c MD |
57 | return 0; |
58 | ||
59 | payload.ip = (unsigned long) krpi->rp->kp.addr; | |
60 | payload.parent_ip = (unsigned long) krpi->ret_addr; | |
61 | ||
79150a49 | 62 | lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx, sizeof(payload), |
a90917c3 | 63 | lttng_alignof(payload), -1); |
7371f44c MD |
64 | ret = chan->ops->event_reserve(&ctx, event->id); |
65 | if (ret < 0) | |
66 | return 0; | |
a90917c3 | 67 | lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload)); |
7371f44c MD |
68 | chan->ops->event_write(&ctx, &payload, sizeof(payload)); |
69 | chan->ops->event_commit(&ctx); | |
70 | return 0; | |
71 | } | |
72 | ||
73 | static | |
74 | int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi, | |
75 | struct pt_regs *regs) | |
76 | { | |
77 | return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY); | |
78 | } | |
79 | ||
80 | static | |
81 | int lttng_kretprobes_handler_return(struct kretprobe_instance *krpi, | |
82 | struct pt_regs *regs) | |
83 | { | |
84 | return _lttng_kretprobes_handler(krpi, regs, EVENT_RETURN); | |
85 | } | |
86 | ||
87 | /* | |
88 | * Create event description | |
89 | */ | |
90 | static | |
a90917c3 | 91 | int lttng_create_kprobe_event(const char *name, struct lttng_event *event, |
7371f44c MD |
92 | enum lttng_kretprobe_type type) |
93 | { | |
94 | struct lttng_event_field *fields; | |
95 | struct lttng_event_desc *desc; | |
96 | int ret; | |
97 | char *alloc_name; | |
98 | size_t name_len; | |
99 | const char *suffix = NULL; | |
100 | ||
101 | desc = kzalloc(sizeof(*event->desc), GFP_KERNEL); | |
102 | if (!desc) | |
103 | return -ENOMEM; | |
104 | name_len = strlen(name); | |
105 | switch (type) { | |
106 | case EVENT_ENTRY: | |
107 | suffix = "_entry"; | |
108 | break; | |
109 | case EVENT_RETURN: | |
110 | suffix = "_return"; | |
111 | break; | |
112 | } | |
113 | name_len += strlen(suffix); | |
114 | alloc_name = kmalloc(name_len + 1, GFP_KERNEL); | |
115 | if (!alloc_name) { | |
116 | ret = -ENOMEM; | |
117 | goto error_str; | |
118 | } | |
119 | strcpy(alloc_name, name); | |
120 | strcat(alloc_name, suffix); | |
121 | desc->name = alloc_name; | |
122 | desc->nr_fields = 2; | |
123 | desc->fields = fields = | |
124 | kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL); | |
125 | if (!desc->fields) { | |
126 | ret = -ENOMEM; | |
127 | goto error_fields; | |
128 | } | |
129 | fields[0].name = "ip"; | |
130 | fields[0].type.atype = atype_integer; | |
ceabb767 MD |
131 | fields[0].type.u.integer.size = sizeof(unsigned long) * CHAR_BIT; |
132 | fields[0].type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; | |
133 | fields[0].type.u.integer.signedness = lttng_is_signed_type(unsigned long); | |
134 | fields[0].type.u.integer.reverse_byte_order = 0; | |
135 | fields[0].type.u.integer.base = 16; | |
136 | fields[0].type.u.integer.encoding = lttng_encode_none; | |
7371f44c MD |
137 | |
138 | fields[1].name = "parent_ip"; | |
139 | fields[1].type.atype = atype_integer; | |
ceabb767 MD |
140 | fields[1].type.u.integer.size = sizeof(unsigned long) * CHAR_BIT; |
141 | fields[1].type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; | |
142 | fields[1].type.u.integer.signedness = lttng_is_signed_type(unsigned long); | |
143 | fields[1].type.u.integer.reverse_byte_order = 0; | |
144 | fields[1].type.u.integer.base = 16; | |
145 | fields[1].type.u.integer.encoding = lttng_encode_none; | |
7371f44c MD |
146 | |
147 | desc->owner = THIS_MODULE; | |
148 | event->desc = desc; | |
149 | ||
150 | return 0; | |
151 | ||
152 | error_fields: | |
153 | kfree(desc->name); | |
154 | error_str: | |
155 | kfree(desc); | |
156 | return ret; | |
157 | } | |
158 | ||
159 | int lttng_kretprobes_register(const char *name, | |
160 | const char *symbol_name, | |
161 | uint64_t offset, | |
162 | uint64_t addr, | |
a90917c3 MD |
163 | struct lttng_event *event_entry, |
164 | struct lttng_event *event_return) | |
7371f44c MD |
165 | { |
166 | int ret; | |
167 | struct lttng_krp *lttng_krp; | |
168 | ||
169 | /* Kprobes expects a NULL symbol name if unused */ | |
170 | if (symbol_name[0] == '\0') | |
171 | symbol_name = NULL; | |
172 | ||
173 | ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY); | |
174 | if (ret) | |
175 | goto error; | |
176 | ret = lttng_create_kprobe_event(name, event_return, EVENT_RETURN); | |
177 | if (ret) | |
178 | goto event_return_error; | |
179 | lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL); | |
180 | if (!lttng_krp) | |
181 | goto krp_error; | |
182 | lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry; | |
183 | lttng_krp->krp.handler = lttng_kretprobes_handler_return; | |
184 | if (symbol_name) { | |
185 | char *alloc_symbol; | |
186 | ||
187 | alloc_symbol = kstrdup(symbol_name, GFP_KERNEL); | |
188 | if (!alloc_symbol) { | |
189 | ret = -ENOMEM; | |
190 | goto name_error; | |
191 | } | |
192 | lttng_krp->krp.kp.symbol_name = | |
193 | alloc_symbol; | |
194 | event_entry->u.kretprobe.symbol_name = | |
195 | alloc_symbol; | |
196 | event_return->u.kretprobe.symbol_name = | |
197 | alloc_symbol; | |
198 | } | |
199 | lttng_krp->krp.kp.offset = offset; | |
b2c4e8fb | 200 | lttng_krp->krp.kp.addr = (void *) (unsigned long) addr; |
7371f44c MD |
201 | |
202 | /* Allow probe handler to find event structures */ | |
203 | lttng_krp->event[EVENT_ENTRY] = event_entry; | |
204 | lttng_krp->event[EVENT_RETURN] = event_return; | |
205 | event_entry->u.kretprobe.lttng_krp = lttng_krp; | |
206 | event_return->u.kretprobe.lttng_krp = lttng_krp; | |
207 | ||
208 | /* | |
209 | * Both events must be unregistered before the kretprobe is | |
210 | * unregistered. Same for memory allocation. | |
211 | */ | |
212 | kref_init(<tng_krp->kref_alloc); | |
9c1f4643 | 213 | kref_get(<tng_krp->kref_alloc); /* inc refcount to 2, no overflow. */ |
7371f44c | 214 | kref_init(<tng_krp->kref_register); |
9c1f4643 | 215 | kref_get(<tng_krp->kref_register); /* inc refcount to 2, no overflow. */ |
7371f44c | 216 | |
7371f44c MD |
217 | ret = register_kretprobe(<tng_krp->krp); |
218 | if (ret) | |
219 | goto register_error; | |
220 | return 0; | |
221 | ||
222 | register_error: | |
223 | kfree(lttng_krp->krp.kp.symbol_name); | |
224 | name_error: | |
225 | kfree(lttng_krp); | |
226 | krp_error: | |
227 | kfree(event_return->desc->fields); | |
228 | kfree(event_return->desc->name); | |
229 | kfree(event_return->desc); | |
230 | event_return_error: | |
231 | kfree(event_entry->desc->fields); | |
232 | kfree(event_entry->desc->name); | |
233 | kfree(event_entry->desc); | |
234 | error: | |
235 | return ret; | |
236 | } | |
237 | EXPORT_SYMBOL_GPL(lttng_kretprobes_register); | |
238 | ||
239 | static | |
240 | void _lttng_kretprobes_unregister_release(struct kref *kref) | |
241 | { | |
242 | struct lttng_krp *lttng_krp = | |
243 | container_of(kref, struct lttng_krp, kref_register); | |
244 | unregister_kretprobe(<tng_krp->krp); | |
245 | } | |
246 | ||
a90917c3 | 247 | void lttng_kretprobes_unregister(struct lttng_event *event) |
7371f44c MD |
248 | { |
249 | kref_put(&event->u.kretprobe.lttng_krp->kref_register, | |
250 | _lttng_kretprobes_unregister_release); | |
251 | } | |
252 | EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister); | |
253 | ||
254 | static | |
255 | void _lttng_kretprobes_release(struct kref *kref) | |
256 | { | |
257 | struct lttng_krp *lttng_krp = | |
258 | container_of(kref, struct lttng_krp, kref_alloc); | |
259 | kfree(lttng_krp->krp.kp.symbol_name); | |
260 | } | |
261 | ||
a90917c3 | 262 | void lttng_kretprobes_destroy_private(struct lttng_event *event) |
7371f44c MD |
263 | { |
264 | kfree(event->desc->fields); | |
265 | kfree(event->desc->name); | |
266 | kfree(event->desc); | |
267 | kref_put(&event->u.kretprobe.lttng_krp->kref_alloc, | |
268 | _lttng_kretprobes_release); | |
269 | } | |
270 | EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private); | |
271 | ||
a0493bef MD |
272 | int lttng_kretprobes_event_enable_state(struct lttng_event *event, |
273 | int enable) | |
274 | { | |
275 | struct lttng_event *event_return; | |
276 | struct lttng_krp *lttng_krp; | |
277 | ||
278 | if (event->instrumentation != LTTNG_KERNEL_KRETPROBE) { | |
279 | return -EINVAL; | |
280 | } | |
281 | if (event->enabled == enable) { | |
282 | return -EBUSY; | |
283 | } | |
284 | lttng_krp = event->u.kretprobe.lttng_krp; | |
285 | event_return = lttng_krp->event[EVENT_RETURN]; | |
a8f2d0c7 MJ |
286 | WRITE_ONCE(event->enabled, enable); |
287 | WRITE_ONCE(event_return->enabled, enable); | |
a0493bef MD |
288 | return 0; |
289 | } | |
290 | EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state); | |
291 | ||
7371f44c | 292 | MODULE_LICENSE("GPL and additional rights"); |
1c124020 MJ |
293 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
294 | MODULE_DESCRIPTION("LTTng kretprobes probes"); | |
13ab8b0a MD |
295 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
296 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." | |
297 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) | |
298 | LTTNG_MODULES_EXTRAVERSION); |