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baf20995 MD |
1 | /* |
2 | * ltt-debugfs-abi.c | |
3 | * | |
4 | * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
5 | * | |
6 | * LTTng debugfs ABI | |
7 | * | |
8 | * Mimic system calls for: | |
9 | * - session creation, returns a file descriptor or failure. | |
10 | * - channel creation, returns a file descriptor or failure. | |
11 | * - Takes a session file descriptor parameter | |
12 | * - Takes all channel options as parameters. | |
13 | * - event creation, returns a file descriptor or failure. | |
14 | * - Takes an event name as parameter | |
15 | * - Takes an instrumentation source as parameter | |
16 | * - e.g. tracepoints, dynamic_probes... | |
17 | * - Takes instrumentation source specific arguments. | |
18 | */ | |
19 | ||
20 | #include <linux/debugfs.h> | |
21 | ||
22 | /* | |
23 | * This is LTTng's own personal way to create a system call as an external | |
24 | * module. We use ioctl() on /sys/kernel/debug/lttng. | |
25 | */ | |
26 | ||
27 | static struct dentry *lttng_dentry; | |
28 | ||
29 | /* | |
30 | * LTTng DebugFS ABI structures. | |
31 | */ | |
32 | ||
33 | struct lttng_channel { | |
34 | int session; /* Session file descriptor */ | |
35 | int overwrite; /* 1: overwrite, 0: discard */ | |
36 | u64 subbuf_size; | |
37 | u64 num_subbuf; | |
38 | unsigned int switch_timer_interval; | |
39 | unsigned int read_timer_interval; | |
40 | }; | |
41 | ||
42 | struct lttng_event { | |
43 | int channel; /* Channel file descriptor */ | |
44 | enum instrum_type itype; | |
45 | char name[]; | |
46 | }; | |
47 | ||
48 | int lttng_abi_create_session(void) | |
49 | { | |
50 | struct ltt_session *session; | |
51 | struct file *session_file; | |
52 | int session_fd; | |
53 | ||
54 | session = ltt_session_create() | |
55 | if (!session) | |
56 | return -ENOMEM; | |
57 | session_fd = get_unused_fd_flags(O_RDWR); | |
58 | if (session_fd < 0) { | |
59 | ret = session_fd; | |
60 | goto fd_error; | |
61 | } | |
62 | session_file = anon_inode_getfile("[lttng_session]", | |
63 | <tng_fops, | |
64 | session, O_RDWR); | |
65 | if (IS_ERR(session_file)) { | |
66 | ret = PTR_ERR(session_file); | |
67 | goto file_error; | |
68 | } | |
69 | return session_fd; | |
70 | ||
71 | file_error: | |
72 | put_unused_fd(session_fd); | |
73 | fd_error: | |
74 | ltt_session_destroy(session); | |
75 | return ret; | |
76 | } | |
77 | ||
78 | int lttng_abi_create_channel(struct lttng_channel __user *uchan_param) | |
79 | { | |
80 | struct ltt_channel *chan; | |
81 | struct file *chan_file; | |
82 | struct lttng_channel chan_param; | |
83 | int chan_fd; | |
84 | ||
85 | if (copy_from_user(&chan_param, ucham_param, sizeof(chan_param))) | |
86 | return -EFAULT; | |
87 | /* TODO: fetch session pointer from file descriptor */ | |
88 | chan = ltt_channel_create(); | |
89 | if (!chan) | |
90 | return -ENOMEM; | |
91 | chan_fd = get_unused_fd_flags(O_RDWR); | |
92 | if (chan_fd < 0) { | |
93 | ret = chan_fd; | |
94 | goto fd_error; | |
95 | } | |
96 | chan_file = anon_inode_getfile("[lttng_channel]", | |
97 | <tng_fops, | |
98 | chan, O_RDWR); | |
99 | if (IS_ERR(chan_file)) { | |
100 | ret = PTR_ERR(chan_file); | |
101 | goto file_error; | |
102 | } | |
103 | return chan_fd; | |
104 | ||
105 | file_error: | |
106 | put_unused_fd(chan_fd); | |
107 | fd_error: | |
108 | ltt_channel_destroy(chan); | |
109 | return ret; | |
110 | } | |
111 | ||
112 | /** | |
113 | * lttng_ioctl - lttng syscall through ioctl | |
114 | * | |
115 | * @filp: the file | |
116 | * @cmd: the command | |
117 | * @arg: command arg | |
118 | * | |
119 | * This ioctl implements lttng commands: | |
120 | * LTTNG_SESSION | |
121 | * Returns a LTTng trace session file descriptor | |
122 | * LTTNG_CHANNEL | |
123 | * Returns a LTTng channel file descriptor | |
124 | * LTTNG_EVENT | |
125 | * Returns a file descriptor or failure. | |
126 | * | |
127 | * The returned session will be deleted when its file descriptor is closed. | |
128 | * Channel and event file descriptors also hold a reference on the session. | |
129 | */ | |
130 | long lttng_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) | |
131 | { | |
132 | struct inode *inode = filp->f_dentry->d_inode; | |
133 | ||
134 | switch (cmd) { | |
135 | case LTTNG_SESSION: | |
136 | return lttng_abi_create_session(); | |
137 | case LTTNG_CHANNEL: | |
138 | return lttng_abi_create_channel((struct lttng_channel __user *)arg); | |
139 | case LTTNG_EVENT: | |
140 | return lttng_abi_create_event((struct lttng_event __user *)arg); | |
141 | default: | |
142 | return -ENOIOCTLCMD; | |
143 | } | |
144 | } | |
145 | ||
146 | #ifdef CONFIG_COMPAT | |
147 | long lttng_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) | |
148 | { | |
149 | struct inode *inode = filp->f_dentry->d_inode; | |
150 | ||
151 | switch (cmd) { | |
152 | case LTTNG_SESSION: | |
153 | return lttng_abi_create_session(); | |
154 | case LTTNG_CHANNEL: | |
155 | return lttng_abi_create_channel((struct lttng_channel __user *)arg); | |
156 | case LTTNG_EVENT: | |
157 | return lttng_abi_create_event((struct lttng_event __user *)arg); | |
158 | default: | |
159 | return -ENOIOCTLCMD; | |
160 | } | |
161 | } | |
162 | #endif | |
163 | ||
164 | const struct file_operations lttng_file_operations = { | |
165 | .unlocked_ioctl = lttng_ioctl, | |
166 | #ifdef CONFIG_COMPAT | |
167 | .compat_ioctl = lttng_compat_ioctl, | |
168 | #endif | |
169 | } | |
170 | ||
171 | static int __init ltt_debugfs_abi_init(void) | |
172 | { | |
173 | int ret = 0; | |
174 | ||
175 | lttng_dentry = debugfs_create_file("lttng", NULL); | |
176 | if (IS_ERR(lttng_dentry) || !lttng_dentry) | |
177 | printk(KERN_ERR "Error creating LTTng control file\n"); | |
178 | ret = -ENOMEM; | |
179 | goto error; | |
180 | } | |
181 | error: | |
182 | return ret; | |
183 | } | |
184 | ||
185 | static void __exit ltt_debugfs_abi_exit(void) | |
186 | { | |
187 | debugfs_remote(lttng_dentry); | |
188 | } |