Move alignment into event write callback
[lttng-modules.git] / src / probes / lttng-uprobes.c
... / ...
CommitLineData
1/* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
2 *
3 * probes/lttng-uprobes.c
4 *
5 * LTTng uprobes integration module.
6 *
7 * Copyright (C) 2013 Yannick Brosseau <yannick.brosseau@gmail.com>
8 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
9 *
10 */
11
12#include <wrapper/fdtable.h>
13#include <linux/list.h>
14#include <linux/module.h>
15#include <linux/namei.h>
16#include <linux/slab.h>
17#include <linux/uaccess.h>
18#include <lttng/events.h>
19#include <lttng/events-internal.h>
20#include <lttng/tracer.h>
21#include <wrapper/irqflags.h>
22#include <ringbuffer/frontend_types.h>
23#include <wrapper/uprobes.h>
24#include <wrapper/vmalloc.h>
25
26static
27int lttng_uprobes_event_handler_pre(struct uprobe_consumer *uc, struct pt_regs *regs)
28{
29 struct lttng_uprobe_handler *uprobe_handler =
30 container_of(uc, struct lttng_uprobe_handler, up_consumer);
31 struct lttng_kernel_event_common *event = uprobe_handler->event;
32 struct lttng_kernel_probe_ctx lttng_probe_ctx = {
33 .event = event,
34 .interruptible = !lttng_regs_irqs_disabled(regs),
35 };
36 struct {
37 unsigned long ip;
38 } payload;
39
40 switch (event->type) {
41 case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
42 {
43 struct lttng_kernel_event_recorder *event_recorder =
44 container_of(event, struct lttng_kernel_event_recorder, parent);
45 struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
46
47 if (unlikely(!LTTNG_READ_ONCE(chan->parent.session->active)))
48 return 0;
49 if (unlikely(!LTTNG_READ_ONCE(chan->parent.enabled)))
50 return 0;
51 break;
52 }
53 case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
54 break;
55 default:
56 WARN_ON_ONCE(1);
57 }
58
59 if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
60 return 0;
61
62 switch (event->type) {
63 case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
64 {
65 struct lttng_kernel_event_recorder *event_recorder =
66 container_of(event, struct lttng_kernel_event_recorder, parent);
67 struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
68 struct lttng_kernel_ring_buffer_ctx ctx;
69 int ret;
70
71 lib_ring_buffer_ctx_init(&ctx, event_recorder,
72 sizeof(payload), lttng_alignof(payload), &lttng_probe_ctx);
73
74 ret = chan->ops->event_reserve(&ctx);
75 if (ret < 0)
76 return 0;
77
78 /* Event payload. */
79 payload.ip = (unsigned long)instruction_pointer(regs);
80
81 chan->ops->event_write(&ctx, &payload, sizeof(payload), lttng_alignof(payload));
82 chan->ops->event_commit(&ctx);
83 break;
84 }
85 case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
86 {
87 struct lttng_kernel_event_notifier *event_notifier =
88 container_of(event, struct lttng_kernel_event_notifier, parent);
89 struct lttng_kernel_notification_ctx notif_ctx;
90
91 notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture);
92 event_notifier->notification_send(event_notifier, NULL, NULL, &notif_ctx);
93 break;
94 }
95 default:
96 WARN_ON_ONCE(1);
97 }
98 return 0;
99}
100
101static const struct lttng_kernel_event_field *event_fields[] = {
102 lttng_kernel_static_event_field("ip",
103 lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16),
104 false, false, false),
105};
106
107static const struct lttng_kernel_tracepoint_class tp_class = {
108 .nr_fields = ARRAY_SIZE(event_fields),
109 .fields = event_fields,
110};
111
112/*
113 * Create event description.
114 */
115static
116int lttng_create_uprobe_event(const char *name, struct lttng_kernel_event_recorder *event_recorder)
117{
118 struct lttng_kernel_event_desc *desc;
119 int ret;
120
121 desc = kzalloc(sizeof(*desc), GFP_KERNEL);
122 if (!desc)
123 return -ENOMEM;
124 desc->tp_class = &tp_class;
125 desc->event_name = kstrdup(name, GFP_KERNEL);
126 if (!desc->event_name) {
127 ret = -ENOMEM;
128 goto error_str;
129 }
130 desc->owner = THIS_MODULE;
131 event_recorder->priv->parent.desc = desc;
132
133 return 0;
134
135error_str:
136 kfree(desc);
137 return ret;
138}
139
140/*
141 * Create event_notifier description.
142 */
143static
144int lttng_create_uprobe_event_notifier(const char *name, struct lttng_kernel_event_notifier *event_notifier)
145{
146 struct lttng_kernel_event_desc *desc;
147 int ret;
148
149 desc = kzalloc(sizeof(*desc), GFP_KERNEL);
150 if (!desc)
151 return -ENOMEM;
152 desc->tp_class = &tp_class;
153 desc->event_name = kstrdup(name, GFP_KERNEL);
154 if (!desc->event_name) {
155 ret = -ENOMEM;
156 goto error_str;
157 }
158 desc->owner = THIS_MODULE;
159 event_notifier->priv->parent.desc = desc;
160
161 return 0;
162
163error_str:
164 kfree(desc);
165 return ret;
166}
167
168/*
169 * Returns the inode struct from the current task and an fd. The inode is
170 * grabbed by this function and must be put once we are done with it using
171 * iput().
172 */
173static struct inode *get_inode_from_fd(int fd)
174{
175 struct file *file;
176 struct inode *inode;
177
178 rcu_read_lock();
179 /*
180 * Returns the file backing the given fd. Needs to be done inside an RCU
181 * critical section.
182 */
183 file = lttng_lookup_fd_rcu(fd);
184 if (file == NULL) {
185 printk(KERN_WARNING "LTTng: Cannot access file backing the fd(%d)\n", fd);
186 inode = NULL;
187 goto error;
188 }
189
190 /* Grab a reference on the inode. */
191 inode = igrab(file->f_path.dentry->d_inode);
192 if (inode == NULL)
193 printk(KERN_WARNING "LTTng: Cannot grab a reference on the inode.\n");
194error:
195 rcu_read_unlock();
196 return inode;
197}
198
199
200static
201int lttng_uprobes_add_callsite(struct lttng_uprobe *uprobe,
202 struct lttng_kernel_abi_event_callsite __user *callsite,
203 int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs),
204 void *priv_data)
205{
206 int ret = 0;
207 struct lttng_uprobe_handler *uprobe_handler;
208
209 if (!priv_data) {
210 ret = -EINVAL;
211 goto end;
212 }
213
214 uprobe_handler = kzalloc(sizeof(struct lttng_uprobe_handler), GFP_KERNEL);
215 if (!uprobe_handler) {
216 printk(KERN_WARNING "LTTng: Error allocating uprobe_handler");
217 ret = -ENOMEM;
218 goto end;
219 }
220
221 /* Ensure the memory we just allocated don't notify page faults. */
222 wrapper_vmalloc_sync_mappings();
223
224 uprobe_handler->event = priv_data;
225 uprobe_handler->up_consumer.handler = handler;
226
227 ret = copy_from_user(&uprobe_handler->offset, &callsite->u.uprobe.offset, sizeof(uint64_t));
228 if (ret) {
229 goto register_error;
230 }
231
232 ret = wrapper_uprobe_register(uprobe->inode,
233 uprobe_handler->offset, &uprobe_handler->up_consumer);
234 if (ret) {
235 printk(KERN_WARNING "LTTng: Error registering probe on inode %lu "
236 "and offset 0x%llx\n", uprobe->inode->i_ino,
237 uprobe_handler->offset);
238 ret = -1;
239 goto register_error;
240 }
241
242 list_add(&uprobe_handler->node, &uprobe->head);
243
244 return ret;
245
246register_error:
247 kfree(uprobe_handler);
248end:
249 return ret;
250}
251
252int lttng_uprobes_event_add_callsite(struct lttng_kernel_event_common *event,
253 struct lttng_kernel_abi_event_callsite __user *callsite)
254{
255 return lttng_uprobes_add_callsite(&event->priv->u.uprobe, callsite,
256 lttng_uprobes_event_handler_pre, event);
257}
258EXPORT_SYMBOL_GPL(lttng_uprobes_event_add_callsite);
259
260static
261int lttng_uprobes_register(struct lttng_uprobe *uprobe, int fd)
262{
263 int ret = 0;
264 struct inode *inode;
265
266 inode = get_inode_from_fd(fd);
267 if (!inode) {
268 printk(KERN_WARNING "LTTng: Cannot get inode from fd\n");
269 ret = -EBADF;
270 goto inode_error;
271 }
272 uprobe->inode = inode;
273 INIT_LIST_HEAD(&uprobe->head);
274
275inode_error:
276 return ret;
277}
278
279int lttng_uprobes_register_event(const char *name, int fd, struct lttng_kernel_event_recorder *event_recorder)
280{
281 int ret = 0;
282
283 ret = lttng_create_uprobe_event(name, event_recorder);
284 if (ret)
285 goto error;
286
287 ret = lttng_uprobes_register(&event_recorder->priv->parent.u.uprobe, fd);
288 if (ret)
289 goto register_error;
290
291 return 0;
292
293register_error:
294 kfree(event_recorder->priv->parent.desc->event_name);
295 kfree(event_recorder->priv->parent.desc);
296error:
297 return ret;
298}
299EXPORT_SYMBOL_GPL(lttng_uprobes_register_event);
300
301int lttng_uprobes_register_event_notifier(const char *name, int fd,
302 struct lttng_kernel_event_notifier *event_notifier)
303{
304 int ret = 0;
305
306 ret = lttng_create_uprobe_event_notifier(name, event_notifier);
307 if (ret)
308 goto error;
309
310 ret = lttng_uprobes_register(&event_notifier->priv->parent.u.uprobe, fd);
311 if (ret)
312 goto register_error;
313
314 return 0;
315
316register_error:
317 kfree(event_notifier->priv->parent.desc->event_name);
318 kfree(event_notifier->priv->parent.desc);
319error:
320 return ret;
321}
322EXPORT_SYMBOL_GPL(lttng_uprobes_register_event_notifier);
323
324static
325void lttng_uprobes_unregister(struct inode *inode, struct list_head *head)
326{
327 struct lttng_uprobe_handler *iter, *tmp;
328
329 /*
330 * Iterate over the list of handler, remove each handler from the list
331 * and free the struct.
332 */
333 list_for_each_entry_safe(iter, tmp, head, node) {
334 wrapper_uprobe_unregister(inode, iter->offset, &iter->up_consumer);
335 list_del(&iter->node);
336 kfree(iter);
337 }
338}
339
340void lttng_uprobes_unregister_event(struct lttng_kernel_event_recorder *event_recorder)
341{
342 lttng_uprobes_unregister(event_recorder->priv->parent.u.uprobe.inode, &event_recorder->priv->parent.u.uprobe.head);
343}
344EXPORT_SYMBOL_GPL(lttng_uprobes_unregister_event);
345
346void lttng_uprobes_unregister_event_notifier(struct lttng_kernel_event_notifier *event_notifier)
347{
348 lttng_uprobes_unregister(event_notifier->priv->parent.u.uprobe.inode, &event_notifier->priv->parent.u.uprobe.head);
349}
350EXPORT_SYMBOL_GPL(lttng_uprobes_unregister_event_notifier);
351
352void lttng_uprobes_destroy_event_private(struct lttng_kernel_event_recorder *event_recorder)
353{
354 iput(event_recorder->priv->parent.u.uprobe.inode);
355 kfree(event_recorder->priv->parent.desc->event_name);
356 kfree(event_recorder->priv->parent.desc);
357}
358EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_private);
359
360void lttng_uprobes_destroy_event_notifier_private(struct lttng_kernel_event_notifier *event_notifier)
361{
362 iput(event_notifier->priv->parent.u.uprobe.inode);
363 kfree(event_notifier->priv->parent.desc->event_name);
364 kfree(event_notifier->priv->parent.desc);
365}
366EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_notifier_private);
367
368MODULE_LICENSE("GPL and additional rights");
369MODULE_AUTHOR("Yannick Brosseau");
370MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support");
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