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1 | /* |
2 | * (C) Copyright 2009-2011 - | |
3 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
4 | * | |
5 | * LTTng kretprobes integration module. | |
6 | * | |
7 | * Dual LGPL v2.1/GPL v2 license. | |
8 | */ | |
9 | ||
10 | #include <linux/module.h> | |
11 | #include <linux/kprobes.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/kref.h> | |
14 | #include "../ltt-events.h" | |
15 | #include "../wrapper/ringbuffer/frontend_types.h" | |
16 | #include "../wrapper/vmalloc.h" | |
17 | #include "../ltt-tracer.h" | |
18 | ||
19 | enum lttng_kretprobe_type { | |
20 | EVENT_ENTRY = 0, | |
21 | EVENT_RETURN = 1, | |
22 | }; | |
23 | ||
24 | struct lttng_krp { | |
25 | struct kretprobe krp; | |
26 | struct ltt_event *event[2]; /* ENTRY and RETURN */ | |
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); | |
38 | struct ltt_event *event = | |
39 | lttng_krp->event[type]; | |
40 | struct ltt_channel *chan = event->chan; | |
41 | struct lib_ring_buffer_ctx ctx; | |
42 | int ret; | |
43 | struct { | |
44 | unsigned long ip; | |
45 | unsigned long parent_ip; | |
46 | } payload; | |
47 | ||
48 | if (unlikely(!ACCESS_ONCE(chan->session->active))) | |
49 | return 0; | |
50 | if (unlikely(!ACCESS_ONCE(chan->enabled))) | |
51 | return 0; | |
52 | if (unlikely(!ACCESS_ONCE(event->enabled))) | |
53 | return 0; | |
54 | ||
55 | payload.ip = (unsigned long) krpi->rp->kp.addr; | |
56 | payload.parent_ip = (unsigned long) krpi->ret_addr; | |
57 | ||
58 | lib_ring_buffer_ctx_init(&ctx, chan->chan, event, sizeof(payload), | |
59 | ltt_alignof(payload), -1); | |
60 | ret = chan->ops->event_reserve(&ctx, event->id); | |
61 | if (ret < 0) | |
62 | return 0; | |
63 | lib_ring_buffer_align_ctx(&ctx, ltt_alignof(payload)); | |
64 | chan->ops->event_write(&ctx, &payload, sizeof(payload)); | |
65 | chan->ops->event_commit(&ctx); | |
66 | return 0; | |
67 | } | |
68 | ||
69 | static | |
70 | int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi, | |
71 | struct pt_regs *regs) | |
72 | { | |
73 | return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY); | |
74 | } | |
75 | ||
76 | static | |
77 | int lttng_kretprobes_handler_return(struct kretprobe_instance *krpi, | |
78 | struct pt_regs *regs) | |
79 | { | |
80 | return _lttng_kretprobes_handler(krpi, regs, EVENT_RETURN); | |
81 | } | |
82 | ||
83 | /* | |
84 | * Create event description | |
85 | */ | |
86 | static | |
87 | int lttng_create_kprobe_event(const char *name, struct ltt_event *event, | |
88 | enum lttng_kretprobe_type type) | |
89 | { | |
90 | struct lttng_event_field *fields; | |
91 | struct lttng_event_desc *desc; | |
92 | int ret; | |
93 | char *alloc_name; | |
94 | size_t name_len; | |
95 | const char *suffix = NULL; | |
96 | ||
97 | desc = kzalloc(sizeof(*event->desc), GFP_KERNEL); | |
98 | if (!desc) | |
99 | return -ENOMEM; | |
100 | name_len = strlen(name); | |
101 | switch (type) { | |
102 | case EVENT_ENTRY: | |
103 | suffix = "_entry"; | |
104 | break; | |
105 | case EVENT_RETURN: | |
106 | suffix = "_return"; | |
107 | break; | |
108 | } | |
109 | name_len += strlen(suffix); | |
110 | alloc_name = kmalloc(name_len + 1, GFP_KERNEL); | |
111 | if (!alloc_name) { | |
112 | ret = -ENOMEM; | |
113 | goto error_str; | |
114 | } | |
115 | strcpy(alloc_name, name); | |
116 | strcat(alloc_name, suffix); | |
117 | desc->name = alloc_name; | |
118 | desc->nr_fields = 2; | |
119 | desc->fields = fields = | |
120 | kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL); | |
121 | if (!desc->fields) { | |
122 | ret = -ENOMEM; | |
123 | goto error_fields; | |
124 | } | |
125 | fields[0].name = "ip"; | |
126 | fields[0].type.atype = atype_integer; | |
127 | fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT; | |
128 | fields[0].type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT; | |
129 | fields[0].type.u.basic.integer.signedness = is_signed_type(unsigned long); | |
130 | fields[0].type.u.basic.integer.reverse_byte_order = 0; | |
131 | fields[0].type.u.basic.integer.base = 16; | |
132 | fields[0].type.u.basic.integer.encoding = lttng_encode_none; | |
133 | ||
134 | fields[1].name = "parent_ip"; | |
135 | fields[1].type.atype = atype_integer; | |
136 | fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT; | |
137 | fields[1].type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT; | |
138 | fields[1].type.u.basic.integer.signedness = is_signed_type(unsigned long); | |
139 | fields[1].type.u.basic.integer.reverse_byte_order = 0; | |
140 | fields[1].type.u.basic.integer.base = 16; | |
141 | fields[1].type.u.basic.integer.encoding = lttng_encode_none; | |
142 | ||
143 | desc->owner = THIS_MODULE; | |
144 | event->desc = desc; | |
145 | ||
146 | return 0; | |
147 | ||
148 | error_fields: | |
149 | kfree(desc->name); | |
150 | error_str: | |
151 | kfree(desc); | |
152 | return ret; | |
153 | } | |
154 | ||
155 | int lttng_kretprobes_register(const char *name, | |
156 | const char *symbol_name, | |
157 | uint64_t offset, | |
158 | uint64_t addr, | |
159 | struct ltt_event *event_entry, | |
160 | struct ltt_event *event_return) | |
161 | { | |
162 | int ret; | |
163 | struct lttng_krp *lttng_krp; | |
164 | ||
165 | /* Kprobes expects a NULL symbol name if unused */ | |
166 | if (symbol_name[0] == '\0') | |
167 | symbol_name = NULL; | |
168 | ||
169 | ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY); | |
170 | if (ret) | |
171 | goto error; | |
172 | ret = lttng_create_kprobe_event(name, event_return, EVENT_RETURN); | |
173 | if (ret) | |
174 | goto event_return_error; | |
175 | lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL); | |
176 | if (!lttng_krp) | |
177 | goto krp_error; | |
178 | lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry; | |
179 | lttng_krp->krp.handler = lttng_kretprobes_handler_return; | |
180 | if (symbol_name) { | |
181 | char *alloc_symbol; | |
182 | ||
183 | alloc_symbol = kstrdup(symbol_name, GFP_KERNEL); | |
184 | if (!alloc_symbol) { | |
185 | ret = -ENOMEM; | |
186 | goto name_error; | |
187 | } | |
188 | lttng_krp->krp.kp.symbol_name = | |
189 | alloc_symbol; | |
190 | event_entry->u.kretprobe.symbol_name = | |
191 | alloc_symbol; | |
192 | event_return->u.kretprobe.symbol_name = | |
193 | alloc_symbol; | |
194 | } | |
195 | lttng_krp->krp.kp.offset = offset; | |
196 | lttng_krp->krp.kp.addr = (void *) addr; | |
197 | ||
198 | /* Allow probe handler to find event structures */ | |
199 | lttng_krp->event[EVENT_ENTRY] = event_entry; | |
200 | lttng_krp->event[EVENT_RETURN] = event_return; | |
201 | event_entry->u.kretprobe.lttng_krp = lttng_krp; | |
202 | event_return->u.kretprobe.lttng_krp = lttng_krp; | |
203 | ||
204 | /* | |
205 | * Both events must be unregistered before the kretprobe is | |
206 | * unregistered. Same for memory allocation. | |
207 | */ | |
208 | kref_init(<tng_krp->kref_alloc); | |
209 | kref_get(<tng_krp->kref_alloc); /* inc refcount to 2 */ | |
210 | kref_init(<tng_krp->kref_register); | |
211 | kref_get(<tng_krp->kref_register); /* inc refcount to 2 */ | |
212 | ||
213 | /* | |
214 | * Ensure the memory we just allocated don't trigger page faults. | |
215 | * Well.. kprobes itself puts the page fault handler on the blacklist, | |
216 | * but we can never be too careful. | |
217 | */ | |
218 | wrapper_vmalloc_sync_all(); | |
219 | ||
220 | ret = register_kretprobe(<tng_krp->krp); | |
221 | if (ret) | |
222 | goto register_error; | |
223 | return 0; | |
224 | ||
225 | register_error: | |
226 | kfree(lttng_krp->krp.kp.symbol_name); | |
227 | name_error: | |
228 | kfree(lttng_krp); | |
229 | krp_error: | |
230 | kfree(event_return->desc->fields); | |
231 | kfree(event_return->desc->name); | |
232 | kfree(event_return->desc); | |
233 | event_return_error: | |
234 | kfree(event_entry->desc->fields); | |
235 | kfree(event_entry->desc->name); | |
236 | kfree(event_entry->desc); | |
237 | error: | |
238 | return ret; | |
239 | } | |
240 | EXPORT_SYMBOL_GPL(lttng_kretprobes_register); | |
241 | ||
242 | static | |
243 | void _lttng_kretprobes_unregister_release(struct kref *kref) | |
244 | { | |
245 | struct lttng_krp *lttng_krp = | |
246 | container_of(kref, struct lttng_krp, kref_register); | |
247 | unregister_kretprobe(<tng_krp->krp); | |
248 | } | |
249 | ||
250 | void lttng_kretprobes_unregister(struct ltt_event *event) | |
251 | { | |
252 | kref_put(&event->u.kretprobe.lttng_krp->kref_register, | |
253 | _lttng_kretprobes_unregister_release); | |
254 | } | |
255 | EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister); | |
256 | ||
257 | static | |
258 | void _lttng_kretprobes_release(struct kref *kref) | |
259 | { | |
260 | struct lttng_krp *lttng_krp = | |
261 | container_of(kref, struct lttng_krp, kref_alloc); | |
262 | kfree(lttng_krp->krp.kp.symbol_name); | |
263 | } | |
264 | ||
265 | void lttng_kretprobes_destroy_private(struct ltt_event *event) | |
266 | { | |
267 | kfree(event->desc->fields); | |
268 | kfree(event->desc->name); | |
269 | kfree(event->desc); | |
270 | kref_put(&event->u.kretprobe.lttng_krp->kref_alloc, | |
271 | _lttng_kretprobes_release); | |
272 | } | |
273 | EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private); | |
274 | ||
275 | MODULE_LICENSE("GPL and additional rights"); | |
276 | MODULE_AUTHOR("Mathieu Desnoyers"); | |
277 | MODULE_DESCRIPTION("Linux Trace Toolkit Kretprobes Support"); |