src/probes/lttng-uprobes.c

   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/list.h>
  14 #include <linux/module.h>
  15 #include <linux/namei.h>
  16 #include <linux/slab.h>
  17 #include <linux/uaccess.h>
  18 #include <lttng/events.h>
  19 #include <lttng/events-internal.h>
  20 #include <lttng/tracer.h>
  21 #include <wrapper/irqflags.h>
  22 #include <ringbuffer/frontend_types.h>
  23 #include <wrapper/uprobes.h>
  24 #include <wrapper/vmalloc.h>
  25
  26 static
  27 int lttng_uprobes_event_handler_pre(struct uprobe_consumer *uc, struct pt_regs *regs)
  28 {
  29         struct lttng_uprobe_handler *uprobe_handler =
  30                 container_of(uc, struct lttng_uprobe_handler, up_consumer);
  31         struct lttng_kernel_event_common *event = uprobe_handler->event;
  32         struct lttng_kernel_probe_ctx lttng_probe_ctx = {
  33                 .event = event,
  34                 .interruptible = !lttng_regs_irqs_disabled(regs),
  35         };
  36         struct {
  37                 unsigned long ip;
  38         } payload;
  39
  40         switch (event->type) {
  41         case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
  42         {
  43                 struct lttng_kernel_event_recorder *event_recorder =
  44                         container_of(event, struct lttng_kernel_event_recorder, parent);
  45                 struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
  46
  47                 if (unlikely(!LTTNG_READ_ONCE(chan->parent.session->active)))
  48                         return 0;
  49                 if (unlikely(!LTTNG_READ_ONCE(chan->parent.enabled)))
  50                         return 0;
  51                 break;
  52         }
  53         case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
  54                 break;
  55         default:
  56                 WARN_ON_ONCE(1);
  57         }
  58
  59         if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
  60                 return 0;
  61
  62         switch (event->type) {
  63         case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
  64         {
  65                 struct lttng_kernel_event_recorder *event_recorder =
  66                         container_of(event, struct lttng_kernel_event_recorder, parent);
  67                 struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
  68                 struct lttng_kernel_ring_buffer_ctx ctx;
  69                 int ret;
  70
  71                 lib_ring_buffer_ctx_init(&ctx, event_recorder,
  72                         sizeof(payload), lttng_alignof(payload), &lttng_probe_ctx);
  73
  74                 ret = chan->ops->event_reserve(&ctx);
  75                 if (ret < 0)
  76                         return 0;
  77
  78                 /* Event payload. */
  79                 payload.ip = (unsigned long)instruction_pointer(regs);
  80
  81                 lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
  82                 chan->ops->event_write(&ctx, &payload, sizeof(payload));
  83                 chan->ops->event_commit(&ctx);
  84                 break;
  85         }
  86         case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
  87         {
  88                 struct lttng_kernel_event_notifier *event_notifier =
  89                         container_of(event, struct lttng_kernel_event_notifier, parent);
  90                 struct lttng_kernel_notification_ctx notif_ctx;
  91
  92                 notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture);
  93                 event_notifier->notification_send(event_notifier, NULL, NULL, &notif_ctx);
  94                 break;
  95         }
  96         default:
  97                 WARN_ON_ONCE(1);
  98         }
  99         return 0;
 100 }
 101
 102 static const struct lttng_kernel_event_field *event_fields[] = {
 103         lttng_kernel_static_event_field("ip",
 104                 lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16),
 105                 false, false, false),
 106 };
 107
 108 static const struct lttng_kernel_tracepoint_class tp_class = {
 109         .nr_fields = ARRAY_SIZE(event_fields),
 110         .fields = event_fields,
 111 };
 112
 113 /*
 114  * Create event description.
 115  */
 116 static
 117 int lttng_create_uprobe_event(const char *name, struct lttng_kernel_event_recorder *event_recorder)
 118 {
 119         struct lttng_kernel_event_desc *desc;
 120         int ret;
 121
 122         desc = kzalloc(sizeof(*desc), GFP_KERNEL);
 123         if (!desc)
 124                 return -ENOMEM;
 125         desc->tp_class = &tp_class;
 126         desc->event_name = kstrdup(name, GFP_KERNEL);
 127         if (!desc->event_name) {
 128                 ret = -ENOMEM;
 129                 goto error_str;
 130         }
 131         desc->owner = THIS_MODULE;
 132         event_recorder->priv->parent.desc = desc;
 133
 134         return 0;
 135
 136 error_str:
 137         kfree(desc);
 138         return ret;
 139 }
 140
 141 /*
 142  * Create event_notifier description.
 143  */
 144 static
 145 int lttng_create_uprobe_event_notifier(const char *name, struct lttng_kernel_event_notifier *event_notifier)
 146 {
 147         struct lttng_kernel_event_desc *desc;
 148         int ret;
 149
 150         desc = kzalloc(sizeof(*desc), GFP_KERNEL);
 151         if (!desc)
 152                 return -ENOMEM;
 153         desc->tp_class = &tp_class;
 154         desc->event_name = kstrdup(name, GFP_KERNEL);
 155         if (!desc->event_name) {
 156                 ret = -ENOMEM;
 157                 goto error_str;
 158         }
 159         desc->owner = THIS_MODULE;
 160         event_notifier->priv->parent.desc = desc;
 161
 162         return 0;
 163
 164 error_str:
 165         kfree(desc);
 166         return ret;
 167 }
 168
 169 /*
 170  * Returns the inode struct from the current task and an fd. The inode is
 171  * grabbed by this function and must be put once we are done with it using
 172  * iput().
 173  */
 174 static struct inode *get_inode_from_fd(int fd)
 175 {
 176         struct file *file;
 177         struct inode *inode;
 178
 179         rcu_read_lock();
 180         /*
 181          * Returns the file backing the given fd. Needs to be done inside an RCU
 182          * critical section.
 183          */
 184         file = lttng_lookup_fd_rcu(fd);
 185         if (file == NULL) {
 186                 printk(KERN_WARNING "LTTng: Cannot access file backing the fd(%d)\n", fd);
 187                 inode = NULL;
 188                 goto error;
 189         }
 190
 191         /* Grab a reference on the inode. */
 192         inode = igrab(file->f_path.dentry->d_inode);
 193         if (inode == NULL)
 194                 printk(KERN_WARNING "LTTng: Cannot grab a reference on the inode.\n");
 195 error:
 196         rcu_read_unlock();
 197         return inode;
 198 }
 199
 200
 201 static
 202 int lttng_uprobes_add_callsite(struct lttng_uprobe *uprobe,
 203         struct lttng_kernel_abi_event_callsite __user *callsite,
 204         int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs),
 205         void *priv_data)
 206 {
 207         int ret = 0;
 208         struct lttng_uprobe_handler *uprobe_handler;
 209
 210         if (!priv_data) {
 211                 ret = -EINVAL;
 212                 goto end;
 213         }
 214
 215         uprobe_handler = kzalloc(sizeof(struct lttng_uprobe_handler), GFP_KERNEL);
 216         if (!uprobe_handler) {
 217                 printk(KERN_WARNING "LTTng: Error allocating uprobe_handler");
 218                 ret = -ENOMEM;
 219                 goto end;
 220         }
 221
 222         /* Ensure the memory we just allocated don't notify page faults. */
 223         wrapper_vmalloc_sync_mappings();
 224
 225         uprobe_handler->event = priv_data;
 226         uprobe_handler->up_consumer.handler = handler;
 227
 228         ret = copy_from_user(&uprobe_handler->offset, &callsite->u.uprobe.offset, sizeof(uint64_t));
 229         if (ret) {
 230                 goto register_error;
 231         }
 232
 233         ret = wrapper_uprobe_register(uprobe->inode,
 234                       uprobe_handler->offset, &uprobe_handler->up_consumer);
 235         if (ret) {
 236                 printk(KERN_WARNING "LTTng: Error registering probe on inode %lu "
 237                        "and offset 0x%llx\n", uprobe->inode->i_ino,
 238                        uprobe_handler->offset);
 239                 ret = -1;
 240                 goto register_error;
 241         }
 242
 243         list_add(&uprobe_handler->node, &uprobe->head);
 244
 245         return ret;
 246
 247 register_error:
 248         kfree(uprobe_handler);
 249 end:
 250         return ret;
 251 }
 252
 253 int lttng_uprobes_event_add_callsite(struct lttng_kernel_event_common *event,
 254         struct lttng_kernel_abi_event_callsite __user *callsite)
 255 {
 256         return lttng_uprobes_add_callsite(&event->priv->u.uprobe, callsite,
 257                 lttng_uprobes_event_handler_pre, event);
 258 }
 259 EXPORT_SYMBOL_GPL(lttng_uprobes_event_add_callsite);
 260
 261 static
 262 int lttng_uprobes_register(struct lttng_uprobe *uprobe, int fd)
 263 {
 264         int ret = 0;
 265         struct inode *inode;
 266
 267         inode = get_inode_from_fd(fd);
 268         if (!inode) {
 269                 printk(KERN_WARNING "LTTng: Cannot get inode from fd\n");
 270                 ret = -EBADF;
 271                 goto inode_error;
 272         }
 273         uprobe->inode = inode;
 274         INIT_LIST_HEAD(&uprobe->head);
 275
 276 inode_error:
 277         return ret;
 278 }
 279
 280 int lttng_uprobes_register_event(const char *name, int fd, struct lttng_kernel_event_recorder *event_recorder)
 281 {
 282         int ret = 0;
 283
 284         ret = lttng_create_uprobe_event(name, event_recorder);
 285         if (ret)
 286                 goto error;
 287
 288         ret = lttng_uprobes_register(&event_recorder->priv->parent.u.uprobe, fd);
 289         if (ret)
 290                 goto register_error;
 291
 292         return 0;
 293
 294 register_error:
 295         kfree(event_recorder->priv->parent.desc->event_name);
 296         kfree(event_recorder->priv->parent.desc);
 297 error:
 298         return ret;
 299 }
 300 EXPORT_SYMBOL_GPL(lttng_uprobes_register_event);
 301
 302 int lttng_uprobes_register_event_notifier(const char *name, int fd,
 303                 struct lttng_kernel_event_notifier *event_notifier)
 304 {
 305         int ret = 0;
 306
 307         ret = lttng_create_uprobe_event_notifier(name, event_notifier);
 308         if (ret)
 309                 goto error;
 310
 311         ret = lttng_uprobes_register(&event_notifier->priv->parent.u.uprobe, fd);
 312         if (ret)
 313                 goto register_error;
 314
 315         return 0;
 316
 317 register_error:
 318         kfree(event_notifier->priv->parent.desc->event_name);
 319         kfree(event_notifier->priv->parent.desc);
 320 error:
 321         return ret;
 322 }
 323 EXPORT_SYMBOL_GPL(lttng_uprobes_register_event_notifier);
 324
 325 static
 326 void lttng_uprobes_unregister(struct inode *inode, struct list_head *head)
 327 {
 328         struct lttng_uprobe_handler *iter, *tmp;
 329
 330         /*
 331          * Iterate over the list of handler, remove each handler from the list
 332          * and free the struct.
 333          */
 334         list_for_each_entry_safe(iter, tmp, head, node) {
 335                 wrapper_uprobe_unregister(inode, iter->offset, &iter->up_consumer);
 336                 list_del(&iter->node);
 337                 kfree(iter);
 338         }
 339 }
 340
 341 void lttng_uprobes_unregister_event(struct lttng_kernel_event_recorder *event_recorder)
 342 {
 343         lttng_uprobes_unregister(event_recorder->priv->parent.u.uprobe.inode, &event_recorder->priv->parent.u.uprobe.head);
 344 }
 345 EXPORT_SYMBOL_GPL(lttng_uprobes_unregister_event);
 346
 347 void lttng_uprobes_unregister_event_notifier(struct lttng_kernel_event_notifier *event_notifier)
 348 {
 349         lttng_uprobes_unregister(event_notifier->priv->parent.u.uprobe.inode, &event_notifier->priv->parent.u.uprobe.head);
 350 }
 351 EXPORT_SYMBOL_GPL(lttng_uprobes_unregister_event_notifier);
 352
 353 void lttng_uprobes_destroy_event_private(struct lttng_kernel_event_recorder *event_recorder)
 354 {
 355         iput(event_recorder->priv->parent.u.uprobe.inode);
 356         kfree(event_recorder->priv->parent.desc->event_name);
 357         kfree(event_recorder->priv->parent.desc);
 358 }
 359 EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_private);
 360
 361 void lttng_uprobes_destroy_event_notifier_private(struct lttng_kernel_event_notifier *event_notifier)
 362 {
 363         iput(event_notifier->priv->parent.u.uprobe.inode);
 364         kfree(event_notifier->priv->parent.desc->event_name);
 365         kfree(event_notifier->priv->parent.desc);
 366 }
 367 EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_notifier_private);
 368
 369 MODULE_LICENSE("GPL and additional rights");
 370 MODULE_AUTHOR("Yannick Brosseau");
 371 MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support");