6 * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; only
11 * version 2.1 of the License.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include <linux/module.h>
24 #include <linux/tracepoint.h>
25 #include <linux/uaccess.h>
26 #include <linux/gfp.h>
28 #include <linux/proc_fs.h>
29 #include <linux/slab.h>
31 #include <wrapper/vmalloc.h>
32 #include <lttng-events.h>
34 #define TP_MODULE_NOAUTOLOAD
35 #define LTTNG_PACKAGE_BUILD
36 #define CREATE_TRACE_POINTS
37 #define TRACE_INCLUDE_PATH instrumentation/events/lttng-module
38 #define TRACE_INCLUDE_FILE lttng
39 #define LTTNG_INSTRUMENTATION
41 #include <instrumentation/events/lttng-module/lttng.h>
43 /* Events written through logger are truncated at 1024 bytes */
44 #define LTTNG_LOGGER_COUNT_MAX 1024
45 #define LTTNG_LOGGER_FILE "lttng-logger"
47 DEFINE_TRACE(lttng_logger
);
49 static struct proc_dir_entry
*lttng_logger_dentry
;
52 * lttng_logger_write - write a userspace string into the trace system
54 * @user_buf: user string
55 * @count: length to copy
56 * @ppos: file position
58 * Copy a userspace string into a trace event named "lttng:logger".
59 * Copies at most @count bytes into the event "msg" dynamic array.
60 * Truncates the count at LTTNG_LOGGER_COUNT_MAX. Returns the number of
61 * bytes copied from the source.
62 * Return -1 on error, with EFAULT errno.
65 ssize_t
lttng_logger_write(struct file
*file
, const char __user
*user_buf
,
66 size_t count
, loff_t
*ppos
)
69 unsigned long uaddr
= (unsigned long) user_buf
;
70 struct page
*pages
[2];
75 if (unlikely(count
> LTTNG_LOGGER_COUNT_MAX
))
76 count
= LTTNG_LOGGER_COUNT_MAX
;
78 /* How many pages are we dealing with ? */
79 if (unlikely((uaddr
& PAGE_MASK
) != ((uaddr
+ count
) & PAGE_MASK
)))
82 /* Pin userspace pages */
83 ret
= get_user_pages_fast(uaddr
, nr_pages
, 0, pages
);
84 if (unlikely(ret
< nr_pages
)) {
94 trace_lttng_logger(user_buf
, count
);
98 for (i
= 0; i
< nr_pages
; i
++)
104 static const struct file_operations lttng_logger_operations
= {
105 .write
= lttng_logger_write
,
109 * Linux 5.6 introduced a separate proc_ops struct for /proc operations
110 * to decouple it from the vfs.
112 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0))
113 static const struct proc_ops lttng_logger_proc_ops
= {
114 .proc_write
= lttng_logger_write
,
117 #define lttng_logger_proc_ops lttng_logger_operations
120 int __init
lttng_logger_init(void)
124 wrapper_vmalloc_sync_all();
125 lttng_logger_dentry
= proc_create_data(LTTNG_LOGGER_FILE
,
126 S_IRUGO
| S_IWUGO
, NULL
,
127 <tng_logger_proc_ops
, NULL
);
128 if (!lttng_logger_dentry
) {
129 printk(KERN_ERR
"Error creating LTTng logger file\n");
133 ret
= __lttng_events_init__lttng();
139 remove_proc_entry("lttng-logger", NULL
);
144 void lttng_logger_exit(void)
146 __lttng_events_exit__lttng();
147 if (lttng_logger_dentry
)
148 remove_proc_entry("lttng-logger", NULL
);