Commit | Line | Data |
---|---|---|
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> |
c190d76e | 17 | #include <wrapper/compiler_attributes.h> |
156a3977 MD |
18 | #include <wrapper/vmalloc.h> |
19 | #include <wrapper/irqflags.h> | |
2df37e95 | 20 | #include <lttng/tracer.h> |
caa068b5 | 21 | #include <blacklist/kprobes.h> |
7371f44c MD |
22 | |
23 | enum lttng_kretprobe_type { | |
1b6cc48a MD |
24 | EVENT_ENTRY = 0, |
25 | EVENT_EXIT = 1, | |
7371f44c MD |
26 | }; |
27 | ||
28 | struct lttng_krp { | |
29 | struct kretprobe krp; | |
e2d5dbc7 | 30 | struct lttng_kernel_event_common *event[2]; /* ENTRY and EXIT */ |
7371f44c MD |
31 | struct kref kref_register; |
32 | struct kref kref_alloc; | |
33 | }; | |
34 | ||
35 | static | |
36 | int _lttng_kretprobes_handler(struct kretprobe_instance *krpi, | |
37 | struct pt_regs *regs, | |
38 | enum lttng_kretprobe_type type) | |
39 | { | |
40 | struct lttng_krp *lttng_krp = | |
08726907 | 41 | container_of(lttng_get_kretprobe(krpi), struct lttng_krp, krp); |
e2d5dbc7 | 42 | struct lttng_kernel_event_common *event = lttng_krp->event[type]; |
a92e844e | 43 | struct lttng_kernel_probe_ctx lttng_probe_ctx = { |
e2d5dbc7 | 44 | .event = event, |
ccecf3fb | 45 | .interruptible = !lttng_regs_irqs_disabled(regs), |
79150a49 | 46 | }; |
7371f44c MD |
47 | struct { |
48 | unsigned long ip; | |
49 | unsigned long parent_ip; | |
50 | } payload; | |
51 | ||
e2d5dbc7 MD |
52 | switch (event->type) { |
53 | case LTTNG_KERNEL_EVENT_TYPE_RECORDER: | |
54 | { | |
55 | struct lttng_kernel_event_recorder *event_recorder = | |
56 | container_of(event, struct lttng_kernel_event_recorder, parent); | |
f7d06400 | 57 | struct lttng_kernel_channel_buffer *chan = event_recorder->chan; |
e2d5dbc7 | 58 | |
f7d06400 | 59 | if (unlikely(!LTTNG_READ_ONCE(chan->parent.session->active))) |
e2d5dbc7 | 60 | return 0; |
f7d06400 | 61 | if (unlikely(!LTTNG_READ_ONCE(chan->parent.enabled))) |
e2d5dbc7 MD |
62 | return 0; |
63 | break; | |
64 | } | |
c190d76e MJ |
65 | case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER: |
66 | lttng_fallthrough; | |
e2d5dbc7 MD |
67 | default: |
68 | WARN_ON_ONCE(1); | |
69 | } | |
7371f44c | 70 | |
e2d5dbc7 | 71 | if (unlikely(!LTTNG_READ_ONCE(event->enabled))) |
7371f44c | 72 | return 0; |
e2d5dbc7 MD |
73 | |
74 | switch (event->type) { | |
75 | case LTTNG_KERNEL_EVENT_TYPE_RECORDER: | |
76 | { | |
77 | struct lttng_kernel_event_recorder *event_recorder = | |
78 | container_of(event, struct lttng_kernel_event_recorder, parent); | |
f7d06400 | 79 | struct lttng_kernel_channel_buffer *chan = event_recorder->chan; |
8a57ec02 | 80 | struct lttng_kernel_ring_buffer_ctx ctx; |
e2d5dbc7 MD |
81 | int ret; |
82 | ||
83 | payload.ip = (unsigned long) lttng_get_kretprobe(krpi)->kp.addr; | |
3c46ddc1 | 84 | payload.parent_ip = lttng_get_kretprobe_retaddr(krpi); |
e2d5dbc7 | 85 | |
b1199bd3 MD |
86 | lib_ring_buffer_ctx_init(&ctx, event_recorder, sizeof(payload), |
87 | lttng_alignof(payload), <tng_probe_ctx); | |
c2fb9c1c | 88 | ret = chan->ops->event_reserve(&ctx); |
e2d5dbc7 MD |
89 | if (ret < 0) |
90 | return 0; | |
f5ffbd77 | 91 | chan->ops->event_write(&ctx, &payload, sizeof(payload), lttng_alignof(payload)); |
e2d5dbc7 MD |
92 | chan->ops->event_commit(&ctx); |
93 | break; | |
94 | } | |
c190d76e MJ |
95 | case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER: |
96 | lttng_fallthrough; | |
e2d5dbc7 MD |
97 | default: |
98 | WARN_ON_ONCE(1); | |
99 | } | |
7371f44c MD |
100 | return 0; |
101 | } | |
102 | ||
103 | static | |
104 | int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi, | |
105 | struct pt_regs *regs) | |
106 | { | |
107 | return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY); | |
108 | } | |
109 | ||
110 | static | |
1b6cc48a MD |
111 | int lttng_kretprobes_handler_exit(struct kretprobe_instance *krpi, |
112 | struct pt_regs *regs) | |
7371f44c | 113 | { |
1b6cc48a | 114 | return _lttng_kretprobes_handler(krpi, regs, EVENT_EXIT); |
7371f44c MD |
115 | } |
116 | ||
6c8c025b MD |
117 | static const struct lttng_kernel_event_field *event_fields[] = { |
118 | lttng_kernel_static_event_field("ip", | |
119 | lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16), | |
4697aac7 | 120 | false, false), |
6c8c025b MD |
121 | lttng_kernel_static_event_field("parent_ip", |
122 | lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16), | |
4697aac7 | 123 | false, false), |
6c8c025b MD |
124 | }; |
125 | ||
126 | static const struct lttng_kernel_tracepoint_class tp_class = { | |
127 | .nr_fields = ARRAY_SIZE(event_fields), | |
128 | .fields = event_fields, | |
129 | }; | |
437d5aa5 | 130 | |
7371f44c MD |
131 | /* |
132 | * Create event description | |
133 | */ | |
134 | static | |
eb6b47db | 135 | int lttng_create_kprobe_event(const char *name, struct lttng_kernel_event_common *event, |
7371f44c MD |
136 | enum lttng_kretprobe_type type) |
137 | { | |
437d5aa5 | 138 | struct lttng_kernel_event_desc *desc; |
7371f44c MD |
139 | char *alloc_name; |
140 | size_t name_len; | |
141 | const char *suffix = NULL; | |
437d5aa5 | 142 | int ret; |
7371f44c | 143 | |
437d5aa5 | 144 | desc = kzalloc(sizeof(*desc), GFP_KERNEL); |
7371f44c MD |
145 | if (!desc) |
146 | return -ENOMEM; | |
147 | name_len = strlen(name); | |
148 | switch (type) { | |
149 | case EVENT_ENTRY: | |
150 | suffix = "_entry"; | |
151 | break; | |
1b6cc48a MD |
152 | case EVENT_EXIT: |
153 | suffix = "_exit"; | |
7371f44c MD |
154 | break; |
155 | } | |
156 | name_len += strlen(suffix); | |
157 | alloc_name = kmalloc(name_len + 1, GFP_KERNEL); | |
158 | if (!alloc_name) { | |
159 | ret = -ENOMEM; | |
160 | goto error_str; | |
161 | } | |
162 | strcpy(alloc_name, name); | |
163 | strcat(alloc_name, suffix); | |
437d5aa5 | 164 | desc->event_name = alloc_name; |
6c8c025b | 165 | desc->tp_class = &tp_class; |
7371f44c | 166 | desc->owner = THIS_MODULE; |
eb6b47db | 167 | event->priv->desc = desc; |
7371f44c MD |
168 | |
169 | return 0; | |
170 | ||
7371f44c MD |
171 | error_str: |
172 | kfree(desc); | |
173 | return ret; | |
174 | } | |
175 | ||
176 | int lttng_kretprobes_register(const char *name, | |
177 | const char *symbol_name, | |
178 | uint64_t offset, | |
179 | uint64_t addr, | |
eb6b47db MD |
180 | struct lttng_kernel_event_common *event_entry, |
181 | struct lttng_kernel_event_common *event_exit) | |
7371f44c MD |
182 | { |
183 | int ret; | |
184 | struct lttng_krp *lttng_krp; | |
185 | ||
186 | /* Kprobes expects a NULL symbol name if unused */ | |
187 | if (symbol_name[0] == '\0') | |
188 | symbol_name = NULL; | |
189 | ||
eb6b47db | 190 | ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY); |
7371f44c MD |
191 | if (ret) |
192 | goto error; | |
eb6b47db | 193 | ret = lttng_create_kprobe_event(name, event_exit, EVENT_EXIT); |
7371f44c | 194 | if (ret) |
1b6cc48a | 195 | goto event_exit_error; |
7371f44c MD |
196 | lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL); |
197 | if (!lttng_krp) | |
198 | goto krp_error; | |
199 | lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry; | |
1b6cc48a | 200 | lttng_krp->krp.handler = lttng_kretprobes_handler_exit; |
7371f44c MD |
201 | if (symbol_name) { |
202 | char *alloc_symbol; | |
203 | ||
204 | alloc_symbol = kstrdup(symbol_name, GFP_KERNEL); | |
205 | if (!alloc_symbol) { | |
206 | ret = -ENOMEM; | |
207 | goto name_error; | |
208 | } | |
eb6b47db MD |
209 | lttng_krp->krp.kp.symbol_name = alloc_symbol; |
210 | event_entry->priv->u.kretprobe.symbol_name = alloc_symbol; | |
211 | event_exit->priv->u.kretprobe.symbol_name = alloc_symbol; | |
7371f44c MD |
212 | } |
213 | lttng_krp->krp.kp.offset = offset; | |
b2c4e8fb | 214 | lttng_krp->krp.kp.addr = (void *) (unsigned long) addr; |
7371f44c MD |
215 | |
216 | /* Allow probe handler to find event structures */ | |
eb6b47db MD |
217 | lttng_krp->event[EVENT_ENTRY] = event_entry; |
218 | lttng_krp->event[EVENT_EXIT] = event_exit; | |
219 | event_entry->priv->u.kretprobe.lttng_krp = lttng_krp; | |
220 | event_exit->priv->u.kretprobe.lttng_krp = lttng_krp; | |
7371f44c MD |
221 | |
222 | /* | |
223 | * Both events must be unregistered before the kretprobe is | |
224 | * unregistered. Same for memory allocation. | |
225 | */ | |
226 | kref_init(<tng_krp->kref_alloc); | |
9c1f4643 | 227 | kref_get(<tng_krp->kref_alloc); /* inc refcount to 2, no overflow. */ |
7371f44c | 228 | kref_init(<tng_krp->kref_register); |
9c1f4643 | 229 | kref_get(<tng_krp->kref_register); /* inc refcount to 2, no overflow. */ |
7371f44c MD |
230 | |
231 | /* | |
232 | * Ensure the memory we just allocated don't trigger page faults. | |
233 | * Well.. kprobes itself puts the page fault handler on the blacklist, | |
234 | * but we can never be too careful. | |
235 | */ | |
263b6c88 | 236 | wrapper_vmalloc_sync_mappings(); |
7371f44c MD |
237 | |
238 | ret = register_kretprobe(<tng_krp->krp); | |
239 | if (ret) | |
240 | goto register_error; | |
241 | return 0; | |
242 | ||
243 | register_error: | |
244 | kfree(lttng_krp->krp.kp.symbol_name); | |
245 | name_error: | |
246 | kfree(lttng_krp); | |
247 | krp_error: | |
eb6b47db MD |
248 | kfree(event_exit->priv->desc->event_name); |
249 | kfree(event_exit->priv->desc); | |
1b6cc48a | 250 | event_exit_error: |
eb6b47db MD |
251 | kfree(event_entry->priv->desc->event_name); |
252 | kfree(event_entry->priv->desc); | |
7371f44c MD |
253 | error: |
254 | return ret; | |
255 | } | |
256 | EXPORT_SYMBOL_GPL(lttng_kretprobes_register); | |
257 | ||
258 | static | |
259 | void _lttng_kretprobes_unregister_release(struct kref *kref) | |
260 | { | |
261 | struct lttng_krp *lttng_krp = | |
262 | container_of(kref, struct lttng_krp, kref_register); | |
263 | unregister_kretprobe(<tng_krp->krp); | |
264 | } | |
265 | ||
eb6b47db | 266 | void lttng_kretprobes_unregister(struct lttng_kernel_event_common *event) |
7371f44c | 267 | { |
eb6b47db | 268 | kref_put(&event->priv->u.kretprobe.lttng_krp->kref_register, |
7371f44c MD |
269 | _lttng_kretprobes_unregister_release); |
270 | } | |
271 | EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister); | |
272 | ||
273 | static | |
274 | void _lttng_kretprobes_release(struct kref *kref) | |
275 | { | |
276 | struct lttng_krp *lttng_krp = | |
277 | container_of(kref, struct lttng_krp, kref_alloc); | |
278 | kfree(lttng_krp->krp.kp.symbol_name); | |
279 | } | |
280 | ||
eb6b47db | 281 | void lttng_kretprobes_destroy_private(struct lttng_kernel_event_common *event) |
7371f44c | 282 | { |
eb6b47db MD |
283 | kfree(event->priv->desc->event_name); |
284 | kfree(event->priv->desc); | |
285 | kref_put(&event->priv->u.kretprobe.lttng_krp->kref_alloc, | |
7371f44c MD |
286 | _lttng_kretprobes_release); |
287 | } | |
288 | EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private); | |
289 | ||
e2d5dbc7 | 290 | int lttng_kretprobes_event_enable_state(struct lttng_kernel_event_common *event, |
a0493bef MD |
291 | int enable) |
292 | { | |
e2d5dbc7 | 293 | struct lttng_kernel_event_common *event_exit; |
a0493bef MD |
294 | struct lttng_krp *lttng_krp; |
295 | ||
e2d5dbc7 | 296 | if (event->priv->instrumentation != LTTNG_KERNEL_ABI_KRETPROBE) { |
a0493bef MD |
297 | return -EINVAL; |
298 | } | |
e2d5dbc7 | 299 | if (event->enabled == enable) { |
a0493bef MD |
300 | return -EBUSY; |
301 | } | |
e2d5dbc7 MD |
302 | lttng_krp = event->priv->u.kretprobe.lttng_krp; |
303 | event_exit = lttng_krp->event[EVENT_EXIT]; | |
304 | WRITE_ONCE(event->enabled, enable); | |
305 | WRITE_ONCE(event_exit->enabled, enable); | |
a0493bef MD |
306 | return 0; |
307 | } | |
308 | EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state); | |
309 | ||
7371f44c | 310 | MODULE_LICENSE("GPL and additional rights"); |
1c124020 MJ |
311 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
312 | MODULE_DESCRIPTION("LTTng kretprobes probes"); | |
13ab8b0a MD |
313 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
314 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." | |
315 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) | |
316 | LTTNG_MODULES_EXTRAVERSION); |