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149b9a9d YB |
1 | /* |
2 | * probes/lttng-uprobes.c | |
3 | * | |
4 | * LTTng uprobes integration module. | |
5 | * | |
6 | * Copyright (C) 2013 Yannick Brosseau <yannick.brosseau@gmail.com> | |
7 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
8 | * | |
9 | * This library is free software; you can redistribute it and/or | |
10 | * modify it under the terms of the GNU Lesser General Public | |
11 | * License as published by the Free Software Foundation; only | |
12 | * version 2.1 of the License. | |
13 | * | |
14 | * This library is distributed in the hope that it will be useful, | |
15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
17 | * Lesser General Public License for more details. | |
18 | * | |
19 | * You should have received a copy of the GNU Lesser General Public | |
20 | * License along with this library; if not, write to the Free Software | |
21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
22 | */ | |
23 | ||
24 | #include <linux/fdtable.h> | |
25 | #include <linux/module.h> | |
26 | #include <linux/namei.h> | |
27 | #include <linux/slab.h> | |
28 | #include <lttng-events.h> | |
29 | #include <lttng-tracer.h> | |
30 | #include <wrapper/irqflags.h> | |
31 | #include <wrapper/ringbuffer/frontend_types.h> | |
32 | #include <wrapper/uprobes.h> | |
33 | #include <wrapper/vmalloc.h> | |
34 | ||
35 | static | |
36 | int lttng_uprobes_handler_pre(struct uprobe_consumer *uc, struct pt_regs *regs) | |
37 | { | |
38 | struct lttng_event *event = | |
39 | container_of(uc, struct lttng_event, u.uprobe.up_consumer); | |
40 | struct lttng_probe_ctx lttng_probe_ctx = { | |
41 | .event = event, | |
42 | .interruptible = !lttng_regs_irqs_disabled(regs), | |
43 | }; | |
44 | struct lttng_channel *chan = event->chan; | |
45 | struct lib_ring_buffer_ctx ctx; | |
46 | int ret; | |
47 | ||
48 | struct { | |
49 | unsigned long ip; | |
56377c91 | 50 | } payload; |
149b9a9d YB |
51 | |
52 | if (unlikely(!ACCESS_ONCE(chan->session->active))) | |
53 | return 0; | |
54 | if (unlikely(!ACCESS_ONCE(chan->enabled))) | |
55 | return 0; | |
56 | if (unlikely(!ACCESS_ONCE(event->enabled))) | |
57 | return 0; | |
58 | ||
59 | lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx, | |
60 | sizeof(payload), lttng_alignof(payload), -1); | |
61 | ||
62 | ret = chan->ops->event_reserve(&ctx, event->id); | |
63 | if (ret < 0) | |
64 | return 0; | |
65 | ||
66 | /* Event payload. */ | |
67 | payload.ip = regs->ip; | |
56377c91 | 68 | |
149b9a9d YB |
69 | lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload)); |
70 | chan->ops->event_write(&ctx, &payload, sizeof(payload)); | |
71 | chan->ops->event_commit(&ctx); | |
72 | return 0; | |
73 | } | |
74 | ||
75 | /* | |
76 | * Create event description. | |
77 | */ | |
78 | static | |
79 | int lttng_create_uprobe_event(const char *name, struct lttng_event *event) | |
80 | { | |
81 | struct lttng_event_desc *desc; | |
82 | struct lttng_event_field *fields; | |
83 | int ret; | |
84 | ||
85 | desc = kzalloc(sizeof(*event->desc), GFP_KERNEL); | |
86 | if (!desc) | |
87 | return -ENOMEM; | |
88 | desc->name = kstrdup(name, GFP_KERNEL); | |
89 | if (!desc->name) { | |
90 | ret = -ENOMEM; | |
91 | goto error_str; | |
92 | } | |
93 | ||
94 | desc->nr_fields = 1; | |
95 | desc->fields = fields = | |
96 | kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL); | |
97 | ||
98 | if (!desc->fields) { | |
99 | ret = -ENOMEM; | |
100 | goto error_fields; | |
101 | } | |
102 | fields[0].name = "ip"; | |
103 | fields[0].type.atype = atype_integer; | |
104 | fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT; | |
105 | fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; | |
106 | fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long); | |
107 | fields[0].type.u.basic.integer.reverse_byte_order = 0; | |
108 | fields[0].type.u.basic.integer.base = 16; | |
109 | fields[0].type.u.basic.integer.encoding = lttng_encode_none; | |
110 | ||
111 | desc->owner = THIS_MODULE; | |
112 | event->desc = desc; | |
113 | ||
114 | return 0; | |
115 | ||
116 | error_fields: | |
117 | kfree(desc->name); | |
118 | error_str: | |
119 | kfree(desc); | |
120 | return ret; | |
121 | } | |
122 | ||
56377c91 FD |
123 | /* |
124 | * Returns the inode struct from the current task and an fd. The inode is | |
125 | * grabbed by this function and must be put once we are done with it using | |
126 | * iput(). | |
127 | */ | |
128 | static struct inode *get_inode_from_fd(int fd) | |
129 | { | |
130 | struct file *file; | |
131 | struct inode *inode; | |
132 | ||
133 | rcu_read_lock(); | |
134 | /* | |
135 | * Returns the file backing the given fd. Needs to be done inside an RCU | |
136 | * critical section. | |
137 | */ | |
138 | file = fcheck(fd); | |
139 | if (file == NULL) { | |
140 | printk(KERN_WARNING "Cannot access file backing the fd(%d)\n", fd); | |
141 | inode = NULL; | |
142 | goto error; | |
143 | } | |
144 | ||
145 | /* Grab a reference on the inode. */ | |
146 | inode = igrab(file->f_path.dentry->d_inode); | |
147 | if (inode == NULL) | |
148 | printk(KERN_WARNING "Cannot grab a reference on the inode.\n"); | |
149 | error: | |
150 | rcu_read_unlock(); | |
151 | return inode; | |
152 | } | |
153 | ||
149b9a9d | 154 | int lttng_uprobes_register(const char *name, |
56377c91 | 155 | int fd, |
149b9a9d YB |
156 | uint64_t offset, |
157 | struct lttng_event *event) | |
158 | { | |
159 | int ret; | |
56377c91 | 160 | struct inode *inode; |
149b9a9d YB |
161 | |
162 | ret = lttng_create_uprobe_event(name, event); | |
163 | if (ret) | |
164 | goto error; | |
165 | ||
56377c91 FD |
166 | inode = get_inode_from_fd(fd); |
167 | if (!inode) { | |
168 | printk(KERN_WARNING "Cannot get inode from fd\n"); | |
169 | ret = -EBADF; | |
170 | goto inode_error; | |
171 | } | |
172 | ||
149b9a9d YB |
173 | memset(&event->u.uprobe.up_consumer, 0, |
174 | sizeof(event->u.uprobe.up_consumer)); | |
175 | ||
176 | event->u.uprobe.up_consumer.handler = lttng_uprobes_handler_pre; | |
56377c91 | 177 | event->u.uprobe.inode = inode; |
149b9a9d YB |
178 | event->u.uprobe.offset = offset; |
179 | ||
180 | /* Ensure the memory we just allocated don't trigger page faults. */ | |
181 | wrapper_vmalloc_sync_all(); | |
149b9a9d YB |
182 | ret = wrapper_uprobe_register(event->u.uprobe.inode, |
183 | event->u.uprobe.offset, | |
184 | &event->u.uprobe.up_consumer); | |
185 | if (ret) { | |
186 | printk(KERN_WARNING "Error registering probe on inode %lu " | |
187 | "and offset %llu\n", event->u.uprobe.inode->i_ino, | |
188 | event->u.uprobe.offset); | |
189 | goto register_error; | |
190 | } | |
191 | return 0; | |
192 | ||
193 | register_error: | |
194 | iput(event->u.uprobe.inode); | |
56377c91 | 195 | inode_error: |
149b9a9d YB |
196 | kfree(event->desc->name); |
197 | kfree(event->desc); | |
198 | error: | |
199 | return ret; | |
200 | } | |
201 | EXPORT_SYMBOL_GPL(lttng_uprobes_register); | |
202 | ||
203 | void lttng_uprobes_unregister(struct lttng_event *event) | |
204 | { | |
205 | wrapper_uprobe_unregister(event->u.uprobe.inode, | |
206 | event->u.uprobe.offset, | |
207 | &event->u.uprobe.up_consumer); | |
208 | } | |
209 | EXPORT_SYMBOL_GPL(lttng_uprobes_unregister); | |
210 | ||
211 | void lttng_uprobes_destroy_private(struct lttng_event *event) | |
212 | { | |
213 | iput(event->u.uprobe.inode); | |
214 | kfree(event->desc->name); | |
215 | kfree(event->desc); | |
216 | } | |
217 | EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_private); | |
218 | ||
219 | MODULE_LICENSE("GPL and additional rights"); | |
220 | MODULE_AUTHOR("Yannick Brosseau"); | |
221 | MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support"); |