| 1 | /* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only) |
| 2 | * |
| 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 | * |
| 10 | */ |
| 11 | |
| 12 | #include <wrapper/fdtable.h> |
| 13 | #include <linux/file.h> |
| 14 | #include <linux/list.h> |
| 15 | #include <linux/module.h> |
| 16 | #include <linux/namei.h> |
| 17 | #include <linux/slab.h> |
| 18 | #include <linux/uaccess.h> |
| 19 | #include <linux/uprobes.h> |
| 20 | |
| 21 | #include <lttng/events.h> |
| 22 | #include <lttng/events-internal.h> |
| 23 | #include <lttng/tracer.h> |
| 24 | #include <wrapper/irqflags.h> |
| 25 | #include <ringbuffer/frontend_types.h> |
| 26 | #include <wrapper/vmalloc.h> |
| 27 | |
| 28 | static |
| 29 | int lttng_uprobes_event_handler_pre(struct uprobe_consumer *uc, struct pt_regs *regs) |
| 30 | { |
| 31 | struct lttng_uprobe_handler *uprobe_handler = |
| 32 | container_of(uc, struct lttng_uprobe_handler, up_consumer); |
| 33 | struct lttng_kernel_event_common *event = uprobe_handler->event; |
| 34 | struct lttng_kernel_probe_ctx lttng_probe_ctx = { |
| 35 | .event = event, |
| 36 | .interruptible = !lttng_regs_irqs_disabled(regs), |
| 37 | }; |
| 38 | struct { |
| 39 | unsigned long ip; |
| 40 | } payload; |
| 41 | |
| 42 | switch (event->type) { |
| 43 | case LTTNG_KERNEL_EVENT_TYPE_RECORDER: |
| 44 | { |
| 45 | struct lttng_kernel_event_recorder *event_recorder = |
| 46 | container_of(event, struct lttng_kernel_event_recorder, parent); |
| 47 | struct lttng_kernel_channel_buffer *chan = event_recorder->chan; |
| 48 | |
| 49 | if (unlikely(!LTTNG_READ_ONCE(chan->parent.session->active))) |
| 50 | return 0; |
| 51 | if (unlikely(!LTTNG_READ_ONCE(chan->parent.enabled))) |
| 52 | return 0; |
| 53 | break; |
| 54 | } |
| 55 | case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER: |
| 56 | break; |
| 57 | default: |
| 58 | WARN_ON_ONCE(1); |
| 59 | } |
| 60 | |
| 61 | if (unlikely(!LTTNG_READ_ONCE(event->enabled))) |
| 62 | return 0; |
| 63 | |
| 64 | switch (event->type) { |
| 65 | case LTTNG_KERNEL_EVENT_TYPE_RECORDER: |
| 66 | { |
| 67 | struct lttng_kernel_event_recorder *event_recorder = |
| 68 | container_of(event, struct lttng_kernel_event_recorder, parent); |
| 69 | struct lttng_kernel_channel_buffer *chan = event_recorder->chan; |
| 70 | struct lttng_kernel_ring_buffer_ctx ctx; |
| 71 | int ret; |
| 72 | |
| 73 | lib_ring_buffer_ctx_init(&ctx, event_recorder, |
| 74 | sizeof(payload), lttng_alignof(payload), <tng_probe_ctx); |
| 75 | |
| 76 | ret = chan->ops->event_reserve(&ctx); |
| 77 | if (ret < 0) |
| 78 | return 0; |
| 79 | |
| 80 | /* Event payload. */ |
| 81 | payload.ip = (unsigned long)instruction_pointer(regs); |
| 82 | |
| 83 | chan->ops->event_write(&ctx, &payload, sizeof(payload), lttng_alignof(payload)); |
| 84 | chan->ops->event_commit(&ctx); |
| 85 | break; |
| 86 | } |
| 87 | case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER: |
| 88 | { |
| 89 | struct lttng_kernel_event_notifier *event_notifier = |
| 90 | container_of(event, struct lttng_kernel_event_notifier, parent); |
| 91 | struct lttng_kernel_notification_ctx notif_ctx; |
| 92 | |
| 93 | notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture); |
| 94 | event_notifier->notification_send(event_notifier, NULL, NULL, ¬if_ctx); |
| 95 | break; |
| 96 | } |
| 97 | default: |
| 98 | WARN_ON_ONCE(1); |
| 99 | } |
| 100 | return 0; |
| 101 | } |
| 102 | |
| 103 | static const struct lttng_kernel_event_field *event_fields[] = { |
| 104 | lttng_kernel_static_event_field("ip", |
| 105 | lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16), |
| 106 | false, false), |
| 107 | }; |
| 108 | |
| 109 | static const struct lttng_kernel_tracepoint_class tp_class = { |
| 110 | .nr_fields = ARRAY_SIZE(event_fields), |
| 111 | .fields = event_fields, |
| 112 | }; |
| 113 | |
| 114 | /* |
| 115 | * Create event description. |
| 116 | */ |
| 117 | static |
| 118 | int lttng_create_uprobe_event(const char *name, struct lttng_kernel_event_common *event) |
| 119 | { |
| 120 | struct lttng_kernel_event_desc *desc; |
| 121 | int ret; |
| 122 | |
| 123 | desc = kzalloc(sizeof(*desc), GFP_KERNEL); |
| 124 | if (!desc) |
| 125 | return -ENOMEM; |
| 126 | desc->tp_class = &tp_class; |
| 127 | desc->event_name = kstrdup(name, GFP_KERNEL); |
| 128 | if (!desc->event_name) { |
| 129 | ret = -ENOMEM; |
| 130 | goto error_str; |
| 131 | } |
| 132 | desc->owner = THIS_MODULE; |
| 133 | event->priv->desc = desc; |
| 134 | |
| 135 | return 0; |
| 136 | |
| 137 | error_str: |
| 138 | kfree(desc); |
| 139 | return ret; |
| 140 | } |
| 141 | |
| 142 | /* |
| 143 | * Returns the inode struct from the current task and an fd. The inode is |
| 144 | * grabbed by this function and must be put once we are done with it using |
| 145 | * iput(). |
| 146 | */ |
| 147 | static struct inode *get_inode_from_fd(int fd) |
| 148 | { |
| 149 | struct file *file; |
| 150 | struct inode *inode; |
| 151 | |
| 152 | rcu_read_lock(); |
| 153 | /* |
| 154 | * Returns the file backing the given fd. Needs to be done inside an RCU |
| 155 | * critical section. |
| 156 | */ |
| 157 | file = lttng_lookup_fdget_rcu(fd); |
| 158 | if (file == NULL) { |
| 159 | printk(KERN_WARNING "LTTng: Cannot access file backing the fd(%d)\n", fd); |
| 160 | inode = NULL; |
| 161 | goto error; |
| 162 | } |
| 163 | |
| 164 | /* Grab a reference on the inode. */ |
| 165 | inode = igrab(file->f_path.dentry->d_inode); |
| 166 | if (inode == NULL) |
| 167 | printk(KERN_WARNING "LTTng: Cannot grab a reference on the inode.\n"); |
| 168 | |
| 169 | error: |
| 170 | rcu_read_unlock(); |
| 171 | if (file) |
| 172 | fput(file); |
| 173 | return inode; |
| 174 | } |
| 175 | |
| 176 | |
| 177 | static |
| 178 | int lttng_uprobes_add_callsite(struct lttng_uprobe *uprobe, |
| 179 | struct lttng_kernel_abi_event_callsite __user *callsite, |
| 180 | int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs), |
| 181 | void *priv_data) |
| 182 | { |
| 183 | int ret = 0; |
| 184 | struct lttng_uprobe_handler *uprobe_handler; |
| 185 | |
| 186 | if (!priv_data) { |
| 187 | ret = -EINVAL; |
| 188 | goto end; |
| 189 | } |
| 190 | |
| 191 | uprobe_handler = kzalloc(sizeof(struct lttng_uprobe_handler), GFP_KERNEL); |
| 192 | if (!uprobe_handler) { |
| 193 | printk(KERN_WARNING "LTTng: Error allocating uprobe_handler"); |
| 194 | ret = -ENOMEM; |
| 195 | goto end; |
| 196 | } |
| 197 | |
| 198 | /* Ensure the memory we just allocated don't notify page faults. */ |
| 199 | wrapper_vmalloc_sync_mappings(); |
| 200 | |
| 201 | uprobe_handler->event = priv_data; |
| 202 | uprobe_handler->up_consumer.handler = handler; |
| 203 | |
| 204 | ret = copy_from_user(&uprobe_handler->offset, &callsite->u.uprobe.offset, sizeof(uint64_t)); |
| 205 | if (ret) { |
| 206 | goto register_error; |
| 207 | } |
| 208 | |
| 209 | ret = uprobe_register(uprobe->inode, |
| 210 | uprobe_handler->offset, &uprobe_handler->up_consumer); |
| 211 | if (ret) { |
| 212 | printk(KERN_WARNING "LTTng: Error registering probe on inode %lu " |
| 213 | "and offset 0x%llx\n", uprobe->inode->i_ino, |
| 214 | uprobe_handler->offset); |
| 215 | ret = -1; |
| 216 | goto register_error; |
| 217 | } |
| 218 | |
| 219 | list_add(&uprobe_handler->node, &uprobe->head); |
| 220 | |
| 221 | return ret; |
| 222 | |
| 223 | register_error: |
| 224 | kfree(uprobe_handler); |
| 225 | end: |
| 226 | return ret; |
| 227 | } |
| 228 | |
| 229 | int lttng_uprobes_event_add_callsite(struct lttng_kernel_event_common *event, |
| 230 | struct lttng_kernel_abi_event_callsite __user *callsite) |
| 231 | { |
| 232 | return lttng_uprobes_add_callsite(&event->priv->u.uprobe, callsite, |
| 233 | lttng_uprobes_event_handler_pre, event); |
| 234 | } |
| 235 | EXPORT_SYMBOL_GPL(lttng_uprobes_event_add_callsite); |
| 236 | |
| 237 | static |
| 238 | int lttng_uprobes_register(struct lttng_uprobe *uprobe, int fd) |
| 239 | { |
| 240 | int ret = 0; |
| 241 | struct inode *inode; |
| 242 | |
| 243 | inode = get_inode_from_fd(fd); |
| 244 | if (!inode) { |
| 245 | printk(KERN_WARNING "LTTng: Cannot get inode from fd\n"); |
| 246 | ret = -EBADF; |
| 247 | goto inode_error; |
| 248 | } |
| 249 | uprobe->inode = inode; |
| 250 | INIT_LIST_HEAD(&uprobe->head); |
| 251 | |
| 252 | inode_error: |
| 253 | return ret; |
| 254 | } |
| 255 | |
| 256 | int lttng_uprobes_register_event(const char *name, int fd, struct lttng_kernel_event_common *event) |
| 257 | { |
| 258 | int ret = 0; |
| 259 | |
| 260 | ret = lttng_create_uprobe_event(name, event); |
| 261 | if (ret) |
| 262 | goto error; |
| 263 | |
| 264 | ret = lttng_uprobes_register(&event->priv->u.uprobe, fd); |
| 265 | if (ret) |
| 266 | goto register_error; |
| 267 | |
| 268 | return 0; |
| 269 | |
| 270 | register_error: |
| 271 | kfree(event->priv->desc->event_name); |
| 272 | kfree(event->priv->desc); |
| 273 | error: |
| 274 | return ret; |
| 275 | } |
| 276 | EXPORT_SYMBOL_GPL(lttng_uprobes_register_event); |
| 277 | |
| 278 | static |
| 279 | void lttng_uprobes_unregister(struct inode *inode, struct list_head *head) |
| 280 | { |
| 281 | struct lttng_uprobe_handler *iter, *tmp; |
| 282 | |
| 283 | /* |
| 284 | * Iterate over the list of handler, remove each handler from the list |
| 285 | * and free the struct. |
| 286 | */ |
| 287 | list_for_each_entry_safe(iter, tmp, head, node) { |
| 288 | uprobe_unregister(inode, iter->offset, &iter->up_consumer); |
| 289 | list_del(&iter->node); |
| 290 | kfree(iter); |
| 291 | } |
| 292 | } |
| 293 | |
| 294 | void lttng_uprobes_unregister_event(struct lttng_kernel_event_common *event) |
| 295 | { |
| 296 | lttng_uprobes_unregister(event->priv->u.uprobe.inode, &event->priv->u.uprobe.head); |
| 297 | } |
| 298 | EXPORT_SYMBOL_GPL(lttng_uprobes_unregister_event); |
| 299 | |
| 300 | void lttng_uprobes_destroy_event_private(struct lttng_kernel_event_common *event) |
| 301 | { |
| 302 | iput(event->priv->u.uprobe.inode); |
| 303 | kfree(event->priv->desc->event_name); |
| 304 | kfree(event->priv->desc); |
| 305 | } |
| 306 | EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_private); |
| 307 | |
| 308 | void lttng_uprobes_destroy_event_notifier_private(struct lttng_kernel_event_notifier *event_notifier) |
| 309 | { |
| 310 | iput(event_notifier->priv->parent.u.uprobe.inode); |
| 311 | kfree(event_notifier->priv->parent.desc->event_name); |
| 312 | kfree(event_notifier->priv->parent.desc); |
| 313 | } |
| 314 | EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_notifier_private); |
| 315 | |
| 316 | MODULE_LICENSE("GPL and additional rights"); |
| 317 | MODULE_AUTHOR("Yannick Brosseau"); |
| 318 | MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support"); |