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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; | |
50 | } payload; | |
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; | |
68 | lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload)); | |
69 | chan->ops->event_write(&ctx, &payload, sizeof(payload)); | |
70 | chan->ops->event_commit(&ctx); | |
71 | return 0; | |
72 | } | |
73 | ||
74 | /* | |
75 | * Create event description. | |
76 | */ | |
77 | static | |
78 | int lttng_create_uprobe_event(const char *name, struct lttng_event *event) | |
79 | { | |
80 | struct lttng_event_desc *desc; | |
81 | struct lttng_event_field *fields; | |
82 | int ret; | |
83 | ||
84 | desc = kzalloc(sizeof(*event->desc), GFP_KERNEL); | |
85 | if (!desc) | |
86 | return -ENOMEM; | |
87 | desc->name = kstrdup(name, GFP_KERNEL); | |
88 | if (!desc->name) { | |
89 | ret = -ENOMEM; | |
90 | goto error_str; | |
91 | } | |
92 | ||
93 | desc->nr_fields = 1; | |
94 | desc->fields = fields = | |
95 | kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL); | |
96 | ||
97 | if (!desc->fields) { | |
98 | ret = -ENOMEM; | |
99 | goto error_fields; | |
100 | } | |
101 | fields[0].name = "ip"; | |
102 | fields[0].type.atype = atype_integer; | |
103 | fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT; | |
104 | fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; | |
105 | fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long); | |
106 | fields[0].type.u.basic.integer.reverse_byte_order = 0; | |
107 | fields[0].type.u.basic.integer.base = 16; | |
108 | fields[0].type.u.basic.integer.encoding = lttng_encode_none; | |
109 | ||
110 | desc->owner = THIS_MODULE; | |
111 | event->desc = desc; | |
112 | ||
113 | return 0; | |
114 | ||
115 | error_fields: | |
116 | kfree(desc->name); | |
117 | error_str: | |
118 | kfree(desc); | |
119 | return ret; | |
120 | } | |
121 | ||
122 | int lttng_uprobes_register(const char *name, | |
123 | const char *path_name, | |
124 | uint64_t offset, | |
125 | struct lttng_event *event) | |
126 | { | |
127 | int ret; | |
128 | ||
129 | /* Shoudl we fail if the path is empty, it should be checked before */ | |
130 | if (path_name[0] == '\0') | |
131 | path_name = NULL; | |
132 | ||
133 | ret = lttng_create_uprobe_event(name, event); | |
134 | if (ret) | |
135 | goto error; | |
136 | ||
137 | memset(&event->u.uprobe.up_consumer, 0, | |
138 | sizeof(event->u.uprobe.up_consumer)); | |
139 | ||
140 | event->u.uprobe.up_consumer.handler = lttng_uprobes_handler_pre; | |
141 | if (path_name) { | |
142 | struct path path; | |
143 | ret = kern_path(path_name, LOOKUP_FOLLOW, &path); | |
144 | if (ret) | |
145 | goto path_error; | |
146 | ||
147 | event->u.uprobe.inode = igrab(path.dentry->d_inode); | |
148 | } | |
149 | event->u.uprobe.offset = offset; | |
150 | ||
151 | /* Ensure the memory we just allocated don't trigger page faults. */ | |
152 | wrapper_vmalloc_sync_all(); | |
153 | printk(KERN_WARNING "Registering probe on inode %lu and offset %llu\n", event->u.uprobe.inode->i_ino, event->u.uprobe.offset); | |
154 | ret = wrapper_uprobe_register(event->u.uprobe.inode, | |
155 | event->u.uprobe.offset, | |
156 | &event->u.uprobe.up_consumer); | |
157 | if (ret) { | |
158 | printk(KERN_WARNING "Error registering probe on inode %lu " | |
159 | "and offset %llu\n", event->u.uprobe.inode->i_ino, | |
160 | event->u.uprobe.offset); | |
161 | goto register_error; | |
162 | } | |
163 | return 0; | |
164 | ||
165 | register_error: | |
166 | iput(event->u.uprobe.inode); | |
167 | path_error: | |
168 | kfree(event->desc->name); | |
169 | kfree(event->desc); | |
170 | error: | |
171 | return ret; | |
172 | } | |
173 | EXPORT_SYMBOL_GPL(lttng_uprobes_register); | |
174 | ||
175 | void lttng_uprobes_unregister(struct lttng_event *event) | |
176 | { | |
177 | wrapper_uprobe_unregister(event->u.uprobe.inode, | |
178 | event->u.uprobe.offset, | |
179 | &event->u.uprobe.up_consumer); | |
180 | } | |
181 | EXPORT_SYMBOL_GPL(lttng_uprobes_unregister); | |
182 | ||
183 | void lttng_uprobes_destroy_private(struct lttng_event *event) | |
184 | { | |
185 | iput(event->u.uprobe.inode); | |
186 | kfree(event->desc->name); | |
187 | kfree(event->desc); | |
188 | } | |
189 | EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_private); | |
190 | ||
191 | MODULE_LICENSE("GPL and additional rights"); | |
192 | MODULE_AUTHOR("Yannick Brosseau"); | |
193 | MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support"); |