| 1 | /* |
| 2 | * lttng.c |
| 3 | * |
| 4 | * LTTng logger ABI |
| 5 | * |
| 6 | * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 7 | * |
| 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. |
| 12 | * |
| 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. |
| 17 | * |
| 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 |
| 21 | */ |
| 22 | |
| 23 | #include <linux/module.h> |
| 24 | #include <linux/tracepoint.h> |
| 25 | #include <linux/uaccess.h> |
| 26 | #include <linux/gfp.h> |
| 27 | #include <linux/fs.h> |
| 28 | #include <linux/proc_fs.h> |
| 29 | #include <linux/slab.h> |
| 30 | #include <linux/mm.h> |
| 31 | #include <wrapper/vmalloc.h> |
| 32 | #include <lttng-events.h> |
| 33 | |
| 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 |
| 40 | |
| 41 | #include <instrumentation/events/lttng-module/lttng.h> |
| 42 | |
| 43 | /* Events written through logger are truncated at 1024 bytes */ |
| 44 | #define LTTNG_LOGGER_COUNT_MAX 1024 |
| 45 | #define LTTNG_LOGGER_FILE "lttng-logger" |
| 46 | |
| 47 | DEFINE_TRACE(lttng_logger); |
| 48 | |
| 49 | static struct proc_dir_entry *lttng_logger_dentry; |
| 50 | |
| 51 | /** |
| 52 | * lttng_logger_write - write a userspace string into the trace system |
| 53 | * @file: file pointer |
| 54 | * @user_buf: user string |
| 55 | * @count: length to copy |
| 56 | * @ppos: file position |
| 57 | * |
| 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. |
| 63 | */ |
| 64 | static |
| 65 | ssize_t lttng_logger_write(struct file *file, const char __user *user_buf, |
| 66 | size_t count, loff_t *ppos) |
| 67 | { |
| 68 | unsigned int nr_pages = 1, i; |
| 69 | unsigned long uaddr = (unsigned long) user_buf; |
| 70 | struct page *pages[2]; |
| 71 | ssize_t written; |
| 72 | int ret; |
| 73 | |
| 74 | /* Truncate count */ |
| 75 | if (unlikely(count > LTTNG_LOGGER_COUNT_MAX)) |
| 76 | count = LTTNG_LOGGER_COUNT_MAX; |
| 77 | |
| 78 | /* How many pages are we dealing with ? */ |
| 79 | if (unlikely((uaddr & PAGE_MASK) != ((uaddr + count) & PAGE_MASK))) |
| 80 | nr_pages = 2; |
| 81 | |
| 82 | /* Pin userspace pages */ |
| 83 | ret = get_user_pages_fast(uaddr, nr_pages, 0, pages); |
| 84 | if (unlikely(ret < nr_pages)) { |
| 85 | if (ret > 0) { |
| 86 | BUG_ON(ret != 1); |
| 87 | put_page(pages[0]); |
| 88 | } |
| 89 | written = -EFAULT; |
| 90 | goto end; |
| 91 | } |
| 92 | |
| 93 | /* Trace the event */ |
| 94 | trace_lttng_logger(user_buf, count); |
| 95 | written = count; |
| 96 | *ppos += written; |
| 97 | |
| 98 | for (i = 0; i < nr_pages; i++) |
| 99 | put_page(pages[i]); |
| 100 | end: |
| 101 | return written; |
| 102 | } |
| 103 | |
| 104 | static const struct file_operations lttng_logger_operations = { |
| 105 | .write = lttng_logger_write, |
| 106 | }; |
| 107 | |
| 108 | int __init lttng_logger_init(void) |
| 109 | { |
| 110 | int ret = 0; |
| 111 | |
| 112 | wrapper_vmalloc_sync_all(); |
| 113 | lttng_logger_dentry = proc_create_data(LTTNG_LOGGER_FILE, |
| 114 | S_IRUGO | S_IWUGO, NULL, |
| 115 | <tng_logger_operations, NULL); |
| 116 | if (!lttng_logger_dentry) { |
| 117 | printk(KERN_ERR "Error creating LTTng logger file\n"); |
| 118 | ret = -ENOMEM; |
| 119 | goto error; |
| 120 | } |
| 121 | ret = __lttng_events_init__lttng(); |
| 122 | if (ret) |
| 123 | goto error_events; |
| 124 | return ret; |
| 125 | |
| 126 | error_events: |
| 127 | remove_proc_entry("lttng-logger", NULL); |
| 128 | error: |
| 129 | return ret; |
| 130 | } |
| 131 | |
| 132 | void lttng_logger_exit(void) |
| 133 | { |
| 134 | __lttng_events_exit__lttng(); |
| 135 | if (lttng_logger_dentry) |
| 136 | remove_proc_entry("lttng-logger", NULL); |
| 137 | } |