src/lttng-statedump-impl.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-statedump.c
   4  *
   5  * Linux Trace Toolkit Next Generation Kernel State Dump
   6  *
   7  * Copyright 2005 Jean-Hugues Deschenes <jean-hugues.deschenes@polymtl.ca>
   8  * Copyright 2006-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   9  *
  10  * Changes:
  11  *      Eric Clement:                   Add listing of network IP interface
  12  *      2006, 2007 Mathieu Desnoyers    Fix kernel threads
  13  *                                      Various updates
  14  */
  15
  16 #include <linux/init.h>
  17 #include <linux/module.h>
  18 #include <linux/netlink.h>
  19 #include <linux/inet.h>
  20 #include <linux/ip.h>
  21 #include <linux/kthread.h>
  22 #include <linux/proc_fs.h>
  23 #include <linux/file.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/irq.h>
  26 #include <linux/irqnr.h>
  27 #include <linux/netdevice.h>
  28 #include <linux/inetdevice.h>
  29 #include <linux/mm.h>
  30 #include <linux/swap.h>
  31 #include <linux/wait.h>
  32 #include <linux/mutex.h>
  33 #include <linux/device.h>
  34
  35 #include <linux/blkdev.h>
  36
  37 #include <lttng/events.h>
  38 #include <lttng/tracer.h>
  39 #include <wrapper/cpu.h>
  40 #include <wrapper/irqdesc.h>
  41 #include <wrapper/fdtable.h>
  42 #include <wrapper/tracepoint.h>
  43 #include <wrapper/blkdev.h>
  44 #include <wrapper/fdtable.h>
  45 #include <wrapper/sched.h>
  46
  47 /* Define the tracepoints, but do not build the probes */
  48 #define CREATE_TRACE_POINTS
  49 #define TRACE_INCLUDE_PATH instrumentation/events
  50 #define TRACE_INCLUDE_FILE lttng-statedump
  51 #define LTTNG_INSTRUMENTATION
  52 #include <instrumentation/events/lttng-statedump.h>
  53
  54 LTTNG_DEFINE_TRACE(lttng_statedump_block_device,
  55         TP_PROTO(struct lttng_kernel_session *session,
  56                 dev_t dev, const char *diskname),
  57         TP_ARGS(session, dev, diskname));
  58
  59 LTTNG_DEFINE_TRACE(lttng_statedump_end,
  60         TP_PROTO(struct lttng_kernel_session *session),
  61         TP_ARGS(session));
  62
  63 LTTNG_DEFINE_TRACE(lttng_statedump_interrupt,
  64         TP_PROTO(struct lttng_kernel_session *session,
  65                 unsigned int irq, const char *chip_name,
  66                 struct irqaction *action),
  67         TP_ARGS(session, irq, chip_name, action));
  68
  69 LTTNG_DEFINE_TRACE(lttng_statedump_file_descriptor,
  70         TP_PROTO(struct lttng_kernel_session *session,
  71                 struct files_struct *files,
  72                 int fd, const char *filename,
  73                 unsigned int flags, fmode_t fmode),
  74         TP_ARGS(session, files, fd, filename, flags, fmode));
  75
  76 LTTNG_DEFINE_TRACE(lttng_statedump_start,
  77         TP_PROTO(struct lttng_kernel_session *session),
  78         TP_ARGS(session));
  79
  80 LTTNG_DEFINE_TRACE(lttng_statedump_process_state,
  81         TP_PROTO(struct lttng_kernel_session *session,
  82                 struct task_struct *p,
  83                 int type, int mode, int submode, int status,
  84                 struct files_struct *files),
  85         TP_ARGS(session, p, type, mode, submode, status, files));
  86
  87 LTTNG_DEFINE_TRACE(lttng_statedump_process_pid_ns,
  88         TP_PROTO(struct lttng_kernel_session *session,
  89                 struct task_struct *p,
  90                 struct pid_namespace *pid_ns),
  91         TP_ARGS(session, p, pid_ns));
  92
  93 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,6,0))
  94 LTTNG_DEFINE_TRACE(lttng_statedump_process_cgroup_ns,
  95         TP_PROTO(struct lttng_kernel_session *session,
  96                 struct task_struct *p,
  97                 struct cgroup_namespace *cgroup_ns),
  98         TP_ARGS(session, p, cgroup_ns));
  99 #endif
 100
 101 LTTNG_DEFINE_TRACE(lttng_statedump_process_ipc_ns,
 102         TP_PROTO(struct lttng_kernel_session *session,
 103                 struct task_struct *p,
 104                 struct ipc_namespace *ipc_ns),
 105         TP_ARGS(session, p, ipc_ns));
 106
 107 #ifndef LTTNG_MNT_NS_MISSING_HEADER
 108 LTTNG_DEFINE_TRACE(lttng_statedump_process_mnt_ns,
 109         TP_PROTO(struct lttng_kernel_session *session,
 110                 struct task_struct *p,
 111                 struct mnt_namespace *mnt_ns),
 112         TP_ARGS(session, p, mnt_ns));
 113 #endif
 114
 115 LTTNG_DEFINE_TRACE(lttng_statedump_process_net_ns,
 116         TP_PROTO(struct lttng_kernel_session *session,
 117                 struct task_struct *p,
 118                 struct net *net_ns),
 119         TP_ARGS(session, p, net_ns));
 120
 121 LTTNG_DEFINE_TRACE(lttng_statedump_process_user_ns,
 122         TP_PROTO(struct lttng_kernel_session *session,
 123                 struct task_struct *p,
 124                 struct user_namespace *user_ns),
 125         TP_ARGS(session, p, user_ns));
 126
 127 LTTNG_DEFINE_TRACE(lttng_statedump_process_uts_ns,
 128         TP_PROTO(struct lttng_kernel_session *session,
 129                 struct task_struct *p,
 130                 struct uts_namespace *uts_ns),
 131         TP_ARGS(session, p, uts_ns));
 132
 133 LTTNG_DEFINE_TRACE(lttng_statedump_process_time_ns,
 134         TP_PROTO(struct lttng_kernel_session *session,
 135                 struct task_struct *p,
 136                 struct time_namespace *time_ns),
 137         TP_ARGS(session, p, time_ns));
 138
 139 LTTNG_DEFINE_TRACE(lttng_statedump_network_interface,
 140         TP_PROTO(struct lttng_kernel_session *session,
 141                 struct net_device *dev, struct in_ifaddr *ifa),
 142         TP_ARGS(session, dev, ifa));
 143
 144 #ifdef LTTNG_HAVE_STATEDUMP_CPU_TOPOLOGY
 145 LTTNG_DEFINE_TRACE(lttng_statedump_cpu_topology,
 146         TP_PROTO(struct lttng_kernel_session *session, struct cpuinfo_x86 *c),
 147         TP_ARGS(session, c));
 148 #endif
 149
 150 struct lttng_fd_ctx {
 151         char *page;
 152         struct lttng_kernel_session *session;
 153         struct files_struct *files;
 154 };
 155
 156 /*
 157  * Protected by the trace lock.
 158  */
 159 static struct delayed_work cpu_work[NR_CPUS];
 160 static DECLARE_WAIT_QUEUE_HEAD(statedump_wq);
 161 static atomic_t kernel_threads_to_run;
 162
 163 enum lttng_thread_type {
 164         LTTNG_USER_THREAD = 0,
 165         LTTNG_KERNEL_THREAD = 1,
 166 };
 167
 168 enum lttng_execution_mode {
 169         LTTNG_USER_MODE = 0,
 170         LTTNG_SYSCALL = 1,
 171         LTTNG_TRAP = 2,
 172         LTTNG_IRQ = 3,
 173         LTTNG_SOFTIRQ = 4,
 174         LTTNG_MODE_UNKNOWN = 5,
 175 };
 176
 177 enum lttng_execution_submode {
 178         LTTNG_NONE = 0,
 179         LTTNG_UNKNOWN = 1,
 180 };
 181
 182 enum lttng_process_status {
 183         LTTNG_UNNAMED = 0,
 184         LTTNG_WAIT_FORK = 1,
 185         LTTNG_WAIT_CPU = 2,
 186         LTTNG_EXIT = 3,
 187         LTTNG_ZOMBIE = 4,
 188         LTTNG_WAIT = 5,
 189         LTTNG_RUN = 6,
 190         LTTNG_DEAD = 7,
 191 };
 192
 193
 194 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(6,0,0) || \
 195     LTTNG_RHEL_KERNEL_RANGE(5,14,0,163,0,0, 5,15,0,0,0,0))
 196
 197 #define LTTNG_PART_STRUCT_TYPE struct block_device
 198
 199 static
 200 int lttng_get_part_name(struct gendisk *disk, struct block_device *part, char *name_buf)
 201 {
 202         int ret;
 203
 204         ret = snprintf(name_buf, BDEVNAME_SIZE, "%pg", part);
 205         if (ret < 0 || ret >= BDEVNAME_SIZE)
 206                 return -ENOSYS;
 207
 208         return 0;
 209 }
 210
 211 static
 212 dev_t lttng_get_part_devt(struct block_device *part)
 213 {
 214         return part->bd_dev;
 215 }
 216
 217 #elif (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,11,0))
 218
 219 #define LTTNG_PART_STRUCT_TYPE struct block_device
 220
 221 static
 222 int lttng_get_part_name(struct gendisk *disk, struct block_device *part, char *name_buf)
 223 {
 224         const char *p;
 225
 226         p = bdevname(part, name_buf);
 227         if (!p)
 228                 return -ENOSYS;
 229
 230         return 0;
 231 }
 232
 233 static
 234 dev_t lttng_get_part_devt(struct block_device *part)
 235 {
 236         return part->bd_dev;
 237 }
 238
 239 #else
 240
 241 #define LTTNG_PART_STRUCT_TYPE struct hd_struct
 242
 243 static
 244 int lttng_get_part_name(struct gendisk *disk, struct hd_struct *part, char *name_buf)
 245 {
 246         const char *p;
 247         struct block_device bdev;
 248
 249         /*
 250          * Create a partial 'struct blockdevice' to use
 251          * 'bdevname()' which is a simple wrapper over
 252          * 'disk_name()' but has the honor to be EXPORT_SYMBOL.
 253          */
 254         bdev.bd_disk = disk;
 255         bdev.bd_part = part;
 256
 257         p = bdevname(&bdev, name_buf);
 258         if (!p)
 259                 return -ENOSYS;
 260
 261         return 0;
 262 }
 263
 264 static
 265 dev_t lttng_get_part_devt(struct hd_struct *part)
 266 {
 267         return part_devt(part);
 268 }
 269 #endif
 270
 271 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,12,0))
 272 static
 273 int lttng_statedump_each_block_device(struct lttng_kernel_session *session, struct gendisk *disk)
 274 {
 275         struct block_device *part;
 276         unsigned long idx;
 277         int ret = 0;
 278
 279         /* Include partition 0 */
 280         idx = 0;
 281
 282         rcu_read_lock();
 283         xa_for_each(&disk->part_tbl, idx, part) {
 284                 char name_buf[BDEVNAME_SIZE];
 285
 286                 /* Exclude non-partitions bdev and empty partitions. */
 287                 if (bdev_is_partition(part) && !bdev_nr_sectors(part))
 288                         continue;
 289
 290                 if (lttng_get_part_name(disk, part, name_buf) == -ENOSYS) {
 291                         ret = -ENOSYS;
 292                         goto end;
 293                 }
 294                 trace_lttng_statedump_block_device(session, lttng_get_part_devt(part),
 295                                 name_buf);
 296         }
 297 end:
 298         rcu_read_unlock();
 299         return ret;
 300 }
 301 #else
 302 static
 303 int lttng_statedump_each_block_device(struct lttng_kernel_session *session, struct gendisk *disk)
 304 {
 305         struct disk_part_iter piter;
 306         LTTNG_PART_STRUCT_TYPE *part;
 307
 308         disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
 309
 310         while ((part = disk_part_iter_next(&piter))) {
 311                 char name_buf[BDEVNAME_SIZE];
 312
 313                 if (lttng_get_part_name(disk, part, name_buf) == -ENOSYS) {
 314                         disk_part_iter_exit(&piter);
 315                         return -ENOSYS;
 316                 }
 317                 trace_lttng_statedump_block_device(session, lttng_get_part_devt(part),
 318                                 name_buf);
 319         }
 320         disk_part_iter_exit(&piter);
 321
 322         return 0;
 323 }
 324 #endif
 325
 326 static
 327 int lttng_enumerate_block_devices(struct lttng_kernel_session *session)
 328 {
 329         struct class *ptr_block_class;
 330         struct device_type *ptr_disk_type;
 331         struct class_dev_iter iter;
 332         struct device *dev;
 333         int ret = 0;
 334
 335         ptr_block_class = wrapper_get_block_class();
 336         if (!ptr_block_class) {
 337                 ret = -ENOSYS;
 338                 goto end;
 339         }
 340         ptr_disk_type = wrapper_get_disk_type();
 341         if (!ptr_disk_type) {
 342                 ret = -ENOSYS;
 343                 goto end;
 344         }
 345         class_dev_iter_init(&iter, ptr_block_class, NULL, ptr_disk_type);
 346         while ((dev = class_dev_iter_next(&iter))) {
 347                 struct gendisk *disk = dev_to_disk(dev);
 348
 349                 /*
 350                  * Don't show empty devices or things that have been
 351                  * suppressed
 352                  */
 353                 if (get_capacity(disk) == 0 ||
 354                     (disk->flags & LTTNG_GENHD_FL_HIDDEN))
 355                         continue;
 356
 357                 ret = lttng_statedump_each_block_device(session, disk);
 358         }
 359         class_dev_iter_exit(&iter);
 360 end:
 361         return ret;
 362 }
 363
 364 #ifdef CONFIG_INET
 365
 366 static
 367 void lttng_enumerate_device(struct lttng_kernel_session *session,
 368                 struct net_device *dev)
 369 {
 370         struct in_device *in_dev;
 371         struct in_ifaddr *ifa;
 372
 373         if (dev->flags & IFF_UP) {
 374                 in_dev = in_dev_get(dev);
 375                 if (in_dev) {
 376                         for (ifa = in_dev->ifa_list; ifa != NULL;
 377                              ifa = ifa->ifa_next) {
 378                                 trace_lttng_statedump_network_interface(
 379                                         session, dev, ifa);
 380                         }
 381                         in_dev_put(in_dev);
 382                 }
 383         } else {
 384                 trace_lttng_statedump_network_interface(
 385                         session, dev, NULL);
 386         }
 387 }
 388
 389 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(6,9,0))
 390 static
 391 int lttng_enumerate_network_ip_interface(struct lttng_kernel_session *session)
 392 {
 393         struct net_device *dev;
 394
 395         rtnl_lock();
 396         for_each_netdev(&init_net, dev)
 397                 lttng_enumerate_device(session, dev);
 398         rtnl_unlock();
 399
 400         return 0;
 401 }
 402 #else
 403 static
 404 int lttng_enumerate_network_ip_interface(struct lttng_kernel_session *session)
 405 {
 406         struct net_device *dev;
 407
 408         read_lock(&dev_base_lock);
 409         for_each_netdev(&init_net, dev)
 410                 lttng_enumerate_device(session, dev);
 411         read_unlock(&dev_base_lock);
 412
 413         return 0;
 414 }
 415 #endif /* (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(6,9,0)) */
 416 #else /* CONFIG_INET */
 417 static inline
 418 int lttng_enumerate_network_ip_interface(struct lttng_kernel_session *session)
 419 {
 420         return 0;
 421 }
 422 #endif /* CONFIG_INET */
 423
 424 static
 425 int lttng_dump_one_fd(const void *p, struct file *file, unsigned int fd)
 426 {
 427         const struct lttng_fd_ctx *ctx = p;
 428         const char *s = d_path(&file->f_path, ctx->page, PAGE_SIZE);
 429         unsigned int flags = file->f_flags;
 430         struct fdtable *fdt;
 431
 432         /*
 433          * We don't expose kernel internal flags, only userspace-visible
 434          * flags.
 435          */
 436         flags &= ~FMODE_NONOTIFY;
 437         fdt = files_fdtable(ctx->files);
 438         /*
 439          * We need to check here again whether fd is within the fdt
 440          * max_fds range, because we might be seeing a different
 441          * files_fdtable() than iterate_fd(), assuming only RCU is
 442          * protecting the read. In reality, iterate_fd() holds
 443          * file_lock, which should ensure the fdt does not change while
 444          * the lock is taken, but we are not aware whether this is
 445          * guaranteed or not, so play safe.
 446          */
 447         if (fd < fdt->max_fds && close_on_exec(fd, fdt))
 448                 flags |= O_CLOEXEC;
 449         if (IS_ERR(s)) {
 450                 struct dentry *dentry = file->f_path.dentry;
 451
 452                 /* Make sure we give at least some info */
 453                 spin_lock(&dentry->d_lock);
 454                 trace_lttng_statedump_file_descriptor(ctx->session,
 455                         ctx->files, fd, dentry->d_name.name, flags,
 456                         file->f_mode);
 457                 spin_unlock(&dentry->d_lock);
 458                 goto end;
 459         }
 460         trace_lttng_statedump_file_descriptor(ctx->session,
 461                 ctx->files, fd, s, flags, file->f_mode);
 462 end:
 463         return 0;
 464 }
 465
 466 /* Called with task lock held. */
 467 static
 468 void lttng_enumerate_files(struct lttng_kernel_session *session,
 469                 struct files_struct *files,
 470                 char *tmp)
 471 {
 472         struct lttng_fd_ctx ctx = { .page = tmp, .session = session, .files = files, };
 473
 474         iterate_fd(files, 0, lttng_dump_one_fd, &ctx);
 475 }
 476
 477 #ifdef LTTNG_HAVE_STATEDUMP_CPU_TOPOLOGY
 478 static
 479 int lttng_enumerate_cpu_topology(struct lttng_kernel_session *session)
 480 {
 481         int cpu;
 482         const cpumask_t *cpumask = cpu_possible_mask;
 483
 484         for (cpu = cpumask_first(cpumask); cpu < nr_cpu_ids;
 485                         cpu = cpumask_next(cpu, cpumask)) {
 486                 trace_lttng_statedump_cpu_topology(session, &cpu_data(cpu));
 487         }
 488
 489         return 0;
 490 }
 491 #else
 492 static
 493 int lttng_enumerate_cpu_topology(struct lttng_kernel_session *session)
 494 {
 495         return 0;
 496 }
 497 #endif
 498
 499 #if 0
 500 /*
 501  * FIXME: we cannot take a mmap_sem while in a RCU read-side critical section
 502  * (scheduling in atomic). Normally, the tasklist lock protects this kind of
 503  * iteration, but it is not exported to modules.
 504  */
 505 static
 506 void lttng_enumerate_task_vm_maps(struct lttng_kernel_session *session,
 507                 struct task_struct *p)
 508 {
 509         struct mm_struct *mm;
 510         struct vm_area_struct *map;
 511         unsigned long ino;
 512
 513         /* get_task_mm does a task_lock... */
 514         mm = get_task_mm(p);
 515         if (!mm)
 516                 return;
 517
 518         map = mm->mmap;
 519         if (map) {
 520                 down_read(&mm->mmap_sem);
 521                 while (map) {
 522                         if (map->vm_file)
 523                                 ino = map->vm_file->f_path.dentry->d_inode->i_ino;
 524                         else
 525                                 ino = 0;
 526                         trace_lttng_statedump_vm_map(session, p, map, ino);
 527                         map = map->vm_next;
 528                 }
 529                 up_read(&mm->mmap_sem);
 530         }
 531         mmput(mm);
 532 }
 533
 534 static
 535 int lttng_enumerate_vm_maps(struct lttng_kernel_session *session)
 536 {
 537         struct task_struct *p;
 538
 539         rcu_read_lock();
 540         for_each_process(p)
 541                 lttng_enumerate_task_vm_maps(session, p);
 542         rcu_read_unlock();
 543         return 0;
 544 }
 545 #endif
 546
 547 static
 548 int lttng_list_interrupts(struct lttng_kernel_session *session)
 549 {
 550         unsigned int irq;
 551         unsigned long flags = 0;
 552         struct irq_desc *desc;
 553
 554 #define irq_to_desc     wrapper_irq_to_desc
 555         /* needs irq_desc */
 556         for_each_irq_desc(irq, desc) {
 557                 struct irqaction *action;
 558                 const char *irq_chip_name =
 559                         irq_desc_get_chip(desc)->name ? : "unnamed_irq_chip";
 560
 561                 local_irq_save(flags);
 562                 raw_spin_lock(&desc->lock);
 563                 for (action = desc->action; action; action = action->next) {
 564                         trace_lttng_statedump_interrupt(session,
 565                                 irq, irq_chip_name, action);
 566                 }
 567                 raw_spin_unlock(&desc->lock);
 568                 local_irq_restore(flags);
 569         }
 570         return 0;
 571 #undef irq_to_desc
 572 }
 573
 574 /*
 575  * Statedump the task's namespaces using the proc filesystem inode number as
 576  * the unique identifier. The user and pid ns are nested and will be dumped
 577  * recursively.
 578  *
 579  * Called with task lock held.
 580  */
 581 static
 582 void lttng_statedump_process_ns(struct lttng_kernel_session *session,
 583                 struct task_struct *p,
 584                 enum lttng_thread_type type,
 585                 enum lttng_execution_mode mode,
 586                 enum lttng_execution_submode submode,
 587                 enum lttng_process_status status)
 588 {
 589         struct nsproxy *proxy;
 590         struct pid_namespace *pid_ns;
 591         struct user_namespace *user_ns;
 592
 593         /*
 594          * The pid and user namespaces are special, they are nested and
 595          * accessed with specific functions instead of the nsproxy struct
 596          * like the other namespaces.
 597          */
 598         pid_ns = task_active_pid_ns(p);
 599         do {
 600                 trace_lttng_statedump_process_pid_ns(session, p, pid_ns);
 601                 pid_ns = pid_ns ? pid_ns->parent : NULL;
 602         } while (pid_ns);
 603
 604
 605         user_ns = task_cred_xxx(p, user_ns);
 606         do {
 607                 trace_lttng_statedump_process_user_ns(session, p, user_ns);
 608                 /*
 609                  * trace_lttng_statedump_process_user_ns() internally
 610                  * checks whether user_ns is NULL. While this does not
 611                  * appear to be a possible return value for
 612                  * task_cred_xxx(), err on the safe side and check
 613                  * for NULL here as well to be consistent with the
 614                  * paranoid behavior of
 615                  * trace_lttng_statedump_process_user_ns().
 616                  */
 617                 user_ns = user_ns ? user_ns->parent : NULL;
 618         } while (user_ns);
 619
 620         proxy = p->nsproxy;
 621
 622         if (proxy) {
 623 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,6,0))
 624                 trace_lttng_statedump_process_cgroup_ns(session, p, proxy->cgroup_ns);
 625 #endif
 626                 trace_lttng_statedump_process_ipc_ns(session, p, proxy->ipc_ns);
 627 #ifndef LTTNG_MNT_NS_MISSING_HEADER
 628                 trace_lttng_statedump_process_mnt_ns(session, p, proxy->mnt_ns);
 629 #endif
 630                 trace_lttng_statedump_process_net_ns(session, p, proxy->net_ns);
 631                 trace_lttng_statedump_process_uts_ns(session, p, proxy->uts_ns);
 632 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,6,0) || \
 633         LTTNG_RHEL_KERNEL_RANGE(4,18,0,305,0,0, 4,19,0,0,0,0))
 634                 trace_lttng_statedump_process_time_ns(session, p, proxy->time_ns);
 635 #endif
 636         }
 637 }
 638
 639 static
 640 int lttng_enumerate_process_states(struct lttng_kernel_session *session)
 641 {
 642         struct task_struct *g, *p;
 643         char *tmp;
 644
 645         tmp = (char *) __get_free_page(GFP_KERNEL);
 646         if (!tmp)
 647                 return -ENOMEM;
 648
 649         rcu_read_lock();
 650         for_each_process(g) {
 651                 struct files_struct *prev_files = NULL;
 652
 653                 p = g;
 654                 do {
 655                         enum lttng_execution_mode mode =
 656                                 LTTNG_MODE_UNKNOWN;
 657                         enum lttng_execution_submode submode =
 658                                 LTTNG_UNKNOWN;
 659                         enum lttng_process_status status;
 660                         enum lttng_thread_type type;
 661                         struct files_struct *files;
 662
 663                         task_lock(p);
 664                         if (p->exit_state == EXIT_ZOMBIE)
 665                                 status = LTTNG_ZOMBIE;
 666                         else if (p->exit_state == EXIT_DEAD)
 667                                 status = LTTNG_DEAD;
 668                         else if (lttng_task_is_running(p)) {
 669                                 /* Is this a forked child that has not run yet? */
 670                                 if (list_empty(&p->rt.run_list))
 671                                         status = LTTNG_WAIT_FORK;
 672                                 else
 673                                         /*
 674                                          * All tasks are considered as wait_cpu;
 675                                          * the viewer will sort out if the task
 676                                          * was really running at this time.
 677                                          */
 678                                         status = LTTNG_WAIT_CPU;
 679                         } else if (lttng_get_task_state(p) &
 680                                 (TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE)) {
 681                                 /* Task is waiting for something to complete */
 682                                 status = LTTNG_WAIT;
 683                         } else
 684                                 status = LTTNG_UNNAMED;
 685                         submode = LTTNG_NONE;
 686
 687                         /*
 688                          * Verification of t->mm is to filter out kernel
 689                          * threads; Viewer will further filter out if a
 690                          * user-space thread was in syscall mode or not.
 691                          */
 692                         if (p->mm)
 693                                 type = LTTNG_USER_THREAD;
 694                         else
 695                                 type = LTTNG_KERNEL_THREAD;
 696                         files = p->files;
 697
 698                         trace_lttng_statedump_process_state(session,
 699                                 p, type, mode, submode, status, files);
 700                         lttng_statedump_process_ns(session,
 701                                 p, type, mode, submode, status);
 702                         /*
 703                          * As an optimisation for the common case, do not
 704                          * repeat information for the same files_struct in
 705                          * two consecutive threads. This is the common case
 706                          * for threads sharing the same fd table. RCU guarantees
 707                          * that the same files_struct pointer is not re-used
 708                          * throughout processes/threads iteration.
 709                          */
 710                         if (files && files != prev_files) {
 711                                 lttng_enumerate_files(session, files, tmp);
 712                                 prev_files = files;
 713                         }
 714                         task_unlock(p);
 715                 } while_each_thread(g, p);
 716         }
 717         rcu_read_unlock();
 718
 719         free_page((unsigned long) tmp);
 720
 721         return 0;
 722 }
 723
 724 static
 725 void lttng_statedump_work_func(struct work_struct *work)
 726 {
 727         if (atomic_dec_and_test(&kernel_threads_to_run))
 728                 /* If we are the last thread, wake up do_lttng_statedump */
 729                 wake_up(&statedump_wq);
 730 }
 731
 732 static
 733 int do_lttng_statedump(struct lttng_kernel_session *session)
 734 {
 735         int cpu, ret;
 736
 737         trace_lttng_statedump_start(session);
 738         ret = lttng_enumerate_process_states(session);
 739         if (ret)
 740                 return ret;
 741         /*
 742          * FIXME
 743          * ret = lttng_enumerate_vm_maps(session);
 744          * if (ret)
 745          *      return ret;
 746          */
 747         ret = lttng_list_interrupts(session);
 748         if (ret)
 749                 return ret;
 750         ret = lttng_enumerate_network_ip_interface(session);
 751         if (ret)
 752                 return ret;
 753         ret = lttng_enumerate_block_devices(session);
 754         switch (ret) {
 755         case 0:
 756                 break;
 757         case -ENOSYS:
 758                 printk(KERN_WARNING "LTTng: block device enumeration is not supported by kernel\n");
 759                 break;
 760         default:
 761                 return ret;
 762         }
 763         ret = lttng_enumerate_cpu_topology(session);
 764         if (ret)
 765                 return ret;
 766
 767         /* TODO lttng_dump_idt_table(session); */
 768         /* TODO lttng_dump_softirq_vec(session); */
 769         /* TODO lttng_list_modules(session); */
 770         /* TODO lttng_dump_swap_files(session); */
 771
 772         /*
 773          * Fire off a work queue on each CPU. Their sole purpose in life
 774          * is to guarantee that each CPU has been in a state where is was in
 775          * syscall mode (i.e. not in a trap, an IRQ or a soft IRQ).
 776          */
 777         lttng_cpus_read_lock();
 778         atomic_set(&kernel_threads_to_run, num_online_cpus());
 779         for_each_online_cpu(cpu) {
 780                 INIT_DELAYED_WORK(&cpu_work[cpu], lttng_statedump_work_func);
 781                 schedule_delayed_work_on(cpu, &cpu_work[cpu], 0);
 782         }
 783         /* Wait for all threads to run */
 784         __wait_event(statedump_wq, (atomic_read(&kernel_threads_to_run) == 0));
 785         lttng_cpus_read_unlock();
 786         /* Our work is done */
 787         trace_lttng_statedump_end(session);
 788         return 0;
 789 }
 790
 791 /*
 792  * Called with session mutex held.
 793  */
 794 int lttng_statedump_start(struct lttng_kernel_session *session)
 795 {
 796         return do_lttng_statedump(session);
 797 }
 798 EXPORT_SYMBOL_GPL(lttng_statedump_start);
 799
 800 static
 801 int __init lttng_statedump_init(void)
 802 {
 803         return 0;
 804 }
 805
 806 module_init(lttng_statedump_init);
 807
 808 static
 809 void __exit lttng_statedump_exit(void)
 810 {
 811 }
 812
 813 module_exit(lttng_statedump_exit);
 814
 815 MODULE_LICENSE("GPL and additional rights");
 816 MODULE_AUTHOR("Jean-Hugues Deschenes");
 817 MODULE_DESCRIPTION("LTTng statedump provider");
 818 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 819         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 820         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 821         LTTNG_MODULES_EXTRAVERSION);