Commit | Line | Data |
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b7cdc182 | 1 | /* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only) |
8134eb60 | 2 | * |
149b9a9d YB |
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 | * | |
149b9a9d YB |
10 | */ |
11 | ||
12 | #include <linux/fdtable.h> | |
3aed4dca | 13 | #include <linux/list.h> |
149b9a9d YB |
14 | #include <linux/module.h> |
15 | #include <linux/namei.h> | |
16 | #include <linux/slab.h> | |
3aed4dca | 17 | #include <linux/uaccess.h> |
a56b8216 | 18 | #include <linux/uprobes.h> |
149b9a9d YB |
19 | #include <lttng-events.h> |
20 | #include <lttng-tracer.h> | |
21 | #include <wrapper/irqflags.h> | |
22 | #include <wrapper/ringbuffer/frontend_types.h> | |
149b9a9d YB |
23 | |
24 | static | |
25 | int lttng_uprobes_handler_pre(struct uprobe_consumer *uc, struct pt_regs *regs) | |
26 | { | |
3aed4dca FD |
27 | struct lttng_uprobe_handler *uprobe_handler = |
28 | container_of(uc, struct lttng_uprobe_handler, up_consumer); | |
29 | struct lttng_event *event = uprobe_handler->event; | |
149b9a9d YB |
30 | struct lttng_probe_ctx lttng_probe_ctx = { |
31 | .event = event, | |
32 | .interruptible = !lttng_regs_irqs_disabled(regs), | |
33 | }; | |
34 | struct lttng_channel *chan = event->chan; | |
35 | struct lib_ring_buffer_ctx ctx; | |
36 | int ret; | |
37 | ||
38 | struct { | |
39 | unsigned long ip; | |
56377c91 | 40 | } payload; |
149b9a9d | 41 | |
b29a9c89 | 42 | if (unlikely(!READ_ONCE(chan->session->active))) |
149b9a9d | 43 | return 0; |
b29a9c89 | 44 | if (unlikely(!READ_ONCE(chan->enabled))) |
149b9a9d | 45 | return 0; |
b29a9c89 | 46 | if (unlikely(!READ_ONCE(event->enabled))) |
149b9a9d YB |
47 | return 0; |
48 | ||
49 | lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx, | |
50 | sizeof(payload), lttng_alignof(payload), -1); | |
51 | ||
52 | ret = chan->ops->event_reserve(&ctx, event->id); | |
53 | if (ret < 0) | |
54 | return 0; | |
55 | ||
56 | /* Event payload. */ | |
7445d54f | 57 | payload.ip = (unsigned long)instruction_pointer(regs); |
56377c91 | 58 | |
149b9a9d YB |
59 | lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload)); |
60 | chan->ops->event_write(&ctx, &payload, sizeof(payload)); | |
61 | chan->ops->event_commit(&ctx); | |
62 | return 0; | |
63 | } | |
64 | ||
65 | /* | |
66 | * Create event description. | |
67 | */ | |
68 | static | |
69 | int lttng_create_uprobe_event(const char *name, struct lttng_event *event) | |
70 | { | |
71 | struct lttng_event_desc *desc; | |
72 | struct lttng_event_field *fields; | |
73 | int ret; | |
74 | ||
75 | desc = kzalloc(sizeof(*event->desc), GFP_KERNEL); | |
76 | if (!desc) | |
77 | return -ENOMEM; | |
78 | desc->name = kstrdup(name, GFP_KERNEL); | |
79 | if (!desc->name) { | |
80 | ret = -ENOMEM; | |
81 | goto error_str; | |
82 | } | |
83 | ||
84 | desc->nr_fields = 1; | |
85 | desc->fields = fields = | |
86 | kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL); | |
87 | ||
88 | if (!desc->fields) { | |
89 | ret = -ENOMEM; | |
90 | goto error_fields; | |
91 | } | |
92 | fields[0].name = "ip"; | |
93 | fields[0].type.atype = atype_integer; | |
ceabb767 MD |
94 | fields[0].type.u.integer.size = sizeof(unsigned long) * CHAR_BIT; |
95 | fields[0].type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; | |
96 | fields[0].type.u.integer.signedness = lttng_is_signed_type(unsigned long); | |
97 | fields[0].type.u.integer.reverse_byte_order = 0; | |
98 | fields[0].type.u.integer.base = 16; | |
99 | fields[0].type.u.integer.encoding = lttng_encode_none; | |
149b9a9d YB |
100 | |
101 | desc->owner = THIS_MODULE; | |
102 | event->desc = desc; | |
103 | ||
104 | return 0; | |
105 | ||
106 | error_fields: | |
107 | kfree(desc->name); | |
108 | error_str: | |
109 | kfree(desc); | |
110 | return ret; | |
111 | } | |
112 | ||
56377c91 FD |
113 | /* |
114 | * Returns the inode struct from the current task and an fd. The inode is | |
115 | * grabbed by this function and must be put once we are done with it using | |
116 | * iput(). | |
117 | */ | |
118 | static struct inode *get_inode_from_fd(int fd) | |
119 | { | |
120 | struct file *file; | |
121 | struct inode *inode; | |
122 | ||
123 | rcu_read_lock(); | |
124 | /* | |
125 | * Returns the file backing the given fd. Needs to be done inside an RCU | |
126 | * critical section. | |
127 | */ | |
128 | file = fcheck(fd); | |
129 | if (file == NULL) { | |
130 | printk(KERN_WARNING "Cannot access file backing the fd(%d)\n", fd); | |
131 | inode = NULL; | |
132 | goto error; | |
133 | } | |
134 | ||
135 | /* Grab a reference on the inode. */ | |
136 | inode = igrab(file->f_path.dentry->d_inode); | |
137 | if (inode == NULL) | |
138 | printk(KERN_WARNING "Cannot grab a reference on the inode.\n"); | |
139 | error: | |
140 | rcu_read_unlock(); | |
141 | return inode; | |
142 | } | |
143 | ||
3aed4dca FD |
144 | int lttng_uprobes_add_callsite(struct lttng_event *event, |
145 | struct lttng_kernel_event_callsite __user *callsite) | |
149b9a9d | 146 | { |
3aed4dca FD |
147 | int ret = 0; |
148 | struct lttng_uprobe_handler *uprobe_handler; | |
149 | ||
150 | if (!event) { | |
151 | ret = -EINVAL; | |
152 | goto end; | |
153 | } | |
154 | ||
155 | uprobe_handler = kzalloc(sizeof(struct lttng_uprobe_handler), GFP_KERNEL); | |
156 | if (!uprobe_handler) { | |
157 | printk(KERN_WARNING "Error allocating uprobe_uprobe_handlers"); | |
158 | ret = -ENOMEM; | |
159 | goto end; | |
160 | } | |
161 | ||
3aed4dca FD |
162 | uprobe_handler->event = event; |
163 | uprobe_handler->up_consumer.handler = lttng_uprobes_handler_pre; | |
164 | ||
165 | ret = copy_from_user(&uprobe_handler->offset, &callsite->u.uprobe.offset, sizeof(uint64_t)); | |
166 | if (ret) { | |
167 | goto register_error; | |
168 | } | |
169 | ||
a56b8216 MD |
170 | ret = uprobe_register(event->u.uprobe.inode, |
171 | uprobe_handler->offset, &uprobe_handler->up_consumer); | |
3aed4dca FD |
172 | if (ret) { |
173 | printk(KERN_WARNING "Error registering probe on inode %lu " | |
174 | "and offset 0x%llx\n", event->u.uprobe.inode->i_ino, | |
175 | uprobe_handler->offset); | |
176 | ret = -1; | |
177 | goto register_error; | |
178 | } | |
179 | ||
180 | list_add(&uprobe_handler->node, &event->u.uprobe.head); | |
181 | ||
182 | return ret; | |
183 | ||
184 | register_error: | |
185 | kfree(uprobe_handler); | |
186 | end: | |
187 | return ret; | |
188 | } | |
189 | EXPORT_SYMBOL_GPL(lttng_uprobes_add_callsite); | |
190 | ||
191 | int lttng_uprobes_register(const char *name, int fd, struct lttng_event *event) | |
192 | { | |
193 | int ret = 0; | |
56377c91 | 194 | struct inode *inode; |
149b9a9d YB |
195 | |
196 | ret = lttng_create_uprobe_event(name, event); | |
197 | if (ret) | |
198 | goto error; | |
199 | ||
56377c91 FD |
200 | inode = get_inode_from_fd(fd); |
201 | if (!inode) { | |
202 | printk(KERN_WARNING "Cannot get inode from fd\n"); | |
203 | ret = -EBADF; | |
204 | goto inode_error; | |
205 | } | |
56377c91 | 206 | event->u.uprobe.inode = inode; |
3aed4dca | 207 | INIT_LIST_HEAD(&event->u.uprobe.head); |
149b9a9d | 208 | |
149b9a9d YB |
209 | return 0; |
210 | ||
56377c91 | 211 | inode_error: |
149b9a9d YB |
212 | kfree(event->desc->name); |
213 | kfree(event->desc); | |
214 | error: | |
215 | return ret; | |
216 | } | |
217 | EXPORT_SYMBOL_GPL(lttng_uprobes_register); | |
218 | ||
219 | void lttng_uprobes_unregister(struct lttng_event *event) | |
220 | { | |
3aed4dca FD |
221 | struct lttng_uprobe_handler *iter, *tmp; |
222 | ||
223 | /* | |
224 | * Iterate over the list of handler, remove each handler from the list | |
225 | * and free the struct. | |
226 | */ | |
227 | list_for_each_entry_safe(iter, tmp, &event->u.uprobe.head, node) { | |
a56b8216 MD |
228 | uprobe_unregister(event->u.uprobe.inode, iter->offset, |
229 | &iter->up_consumer); | |
3aed4dca FD |
230 | list_del(&iter->node); |
231 | kfree(iter); | |
232 | } | |
149b9a9d YB |
233 | } |
234 | EXPORT_SYMBOL_GPL(lttng_uprobes_unregister); | |
235 | ||
236 | void lttng_uprobes_destroy_private(struct lttng_event *event) | |
237 | { | |
238 | iput(event->u.uprobe.inode); | |
239 | kfree(event->desc->name); | |
240 | kfree(event->desc); | |
241 | } | |
242 | EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_private); | |
243 | ||
244 | MODULE_LICENSE("GPL and additional rights"); | |
245 | MODULE_AUTHOR("Yannick Brosseau"); | |
246 | MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support"); |