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