| 1 | /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1) |
| 2 | * |
| 3 | * lttng.c |
| 4 | * |
| 5 | * LTTng logger ABI |
| 6 | * |
| 7 | * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 8 | */ |
| 9 | |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/tracepoint.h> |
| 12 | #include <linux/uaccess.h> |
| 13 | #include <linux/gfp.h> |
| 14 | #include <linux/fs.h> |
| 15 | #include <linux/proc_fs.h> |
| 16 | #include <linux/slab.h> |
| 17 | #include <linux/mm.h> |
| 18 | #include <linux/miscdevice.h> |
| 19 | #include <wrapper/vmalloc.h> |
| 20 | #include <lttng-events.h> |
| 21 | |
| 22 | #define TP_MODULE_NOAUTOLOAD |
| 23 | #define LTTNG_PACKAGE_BUILD |
| 24 | #define CREATE_TRACE_POINTS |
| 25 | #define TRACE_INCLUDE_PATH instrumentation/events/lttng-module |
| 26 | #define TRACE_INCLUDE_FILE lttng |
| 27 | #define LTTNG_INSTRUMENTATION |
| 28 | |
| 29 | #include <instrumentation/events/lttng-module/lttng.h> |
| 30 | |
| 31 | /* Events written through logger are truncated at 1024 bytes */ |
| 32 | #define LTTNG_LOGGER_COUNT_MAX 1024 |
| 33 | #define LTTNG_LOGGER_FILE "lttng-logger" |
| 34 | |
| 35 | DEFINE_TRACE(lttng_logger); |
| 36 | |
| 37 | static struct proc_dir_entry *lttng_logger_dentry; |
| 38 | |
| 39 | /** |
| 40 | * lttng_logger_write - write a userspace string into the trace system |
| 41 | * @file: file pointer |
| 42 | * @user_buf: user string |
| 43 | * @count: length to copy |
| 44 | * @ppos: file position |
| 45 | * |
| 46 | * Copy a userspace string into a trace event named "lttng:logger". |
| 47 | * Copies at most @count bytes into the event "msg" dynamic array. |
| 48 | * Truncates the count at LTTNG_LOGGER_COUNT_MAX. Returns the number of |
| 49 | * bytes copied from the source. |
| 50 | * Return -1 on error, with EFAULT errno. |
| 51 | */ |
| 52 | static |
| 53 | ssize_t lttng_logger_write(struct file *file, const char __user *user_buf, |
| 54 | size_t count, loff_t *ppos) |
| 55 | { |
| 56 | int nr_pages = 1, i; |
| 57 | unsigned long uaddr = (unsigned long) user_buf; |
| 58 | struct page *pages[2]; |
| 59 | ssize_t written; |
| 60 | int ret; |
| 61 | |
| 62 | /* Truncate count */ |
| 63 | if (unlikely(count > LTTNG_LOGGER_COUNT_MAX)) |
| 64 | count = LTTNG_LOGGER_COUNT_MAX; |
| 65 | |
| 66 | /* How many pages are we dealing with ? */ |
| 67 | if (unlikely((uaddr & PAGE_MASK) != ((uaddr + count) & PAGE_MASK))) |
| 68 | nr_pages = 2; |
| 69 | |
| 70 | /* Pin userspace pages */ |
| 71 | ret = get_user_pages_fast(uaddr, nr_pages, 0, pages); |
| 72 | if (unlikely(ret < nr_pages)) { |
| 73 | if (ret > 0) { |
| 74 | BUG_ON(ret != 1); |
| 75 | put_page(pages[0]); |
| 76 | } |
| 77 | written = -EFAULT; |
| 78 | goto end; |
| 79 | } |
| 80 | |
| 81 | /* Trace the event */ |
| 82 | trace_lttng_logger(user_buf, count); |
| 83 | written = count; |
| 84 | *ppos += written; |
| 85 | |
| 86 | for (i = 0; i < nr_pages; i++) |
| 87 | put_page(pages[i]); |
| 88 | end: |
| 89 | return written; |
| 90 | } |
| 91 | |
| 92 | static const struct file_operations lttng_logger_operations = { |
| 93 | .write = lttng_logger_write, |
| 94 | }; |
| 95 | |
| 96 | /* |
| 97 | * Linux 5.6 introduced a separate proc_ops struct for /proc operations |
| 98 | * to decouple it from the vfs. |
| 99 | */ |
| 100 | #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)) |
| 101 | static const struct proc_ops lttng_logger_proc_ops = { |
| 102 | .proc_write = lttng_logger_write, |
| 103 | }; |
| 104 | #else |
| 105 | #define lttng_logger_proc_ops lttng_logger_operations |
| 106 | #endif |
| 107 | |
| 108 | static struct miscdevice logger_dev = { |
| 109 | .minor = MISC_DYNAMIC_MINOR, |
| 110 | .name = "lttng-logger", |
| 111 | .mode = 0666, |
| 112 | .fops = <tng_logger_operations |
| 113 | }; |
| 114 | |
| 115 | int __init lttng_logger_init(void) |
| 116 | { |
| 117 | int ret = 0; |
| 118 | |
| 119 | wrapper_vmalloc_sync_all(); |
| 120 | |
| 121 | /* /dev/lttng-logger */ |
| 122 | ret = misc_register(&logger_dev); |
| 123 | if (ret) { |
| 124 | printk(KERN_ERR "Error creating LTTng logger device\n"); |
| 125 | goto error; |
| 126 | } |
| 127 | |
| 128 | /* /proc/lttng-logger */ |
| 129 | lttng_logger_dentry = proc_create_data(LTTNG_LOGGER_FILE, |
| 130 | S_IRUGO | S_IWUGO, NULL, |
| 131 | <tng_logger_proc_ops, NULL); |
| 132 | if (!lttng_logger_dentry) { |
| 133 | printk(KERN_ERR "Error creating LTTng logger proc file\n"); |
| 134 | ret = -ENOMEM; |
| 135 | goto error_proc; |
| 136 | } |
| 137 | |
| 138 | /* Init */ |
| 139 | ret = __lttng_events_init__lttng(); |
| 140 | if (ret) |
| 141 | goto error_events; |
| 142 | return ret; |
| 143 | |
| 144 | error_events: |
| 145 | remove_proc_entry("lttng-logger", NULL); |
| 146 | error_proc: |
| 147 | misc_deregister(&logger_dev); |
| 148 | error: |
| 149 | return ret; |
| 150 | } |
| 151 | |
| 152 | void lttng_logger_exit(void) |
| 153 | { |
| 154 | __lttng_events_exit__lttng(); |
| 155 | if (lttng_logger_dentry) |
| 156 | remove_proc_entry("lttng-logger", NULL); |
| 157 | misc_deregister(&logger_dev); |
| 158 | } |