arch/um/drivers/mconsole_kern.c

   1 /*
   2  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
   3  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   4  * Licensed under the GPL
   5  */
   6
   7 #include "linux/console.h"
   8 #include "linux/ctype.h"
   9 #include "linux/interrupt.h"
  10 #include "linux/list.h"
  11 #include "linux/mm.h"
  12 #include "linux/module.h"
  13 #include "linux/notifier.h"
  14 #include "linux/reboot.h"
  15 #include "linux/proc_fs.h"
  16 #include "linux/slab.h"
  17 #include "linux/syscalls.h"
  18 #include "linux/utsname.h"
  19 #include "linux/workqueue.h"
  20 #include "asm/uaccess.h"
  21 #include "init.h"
  22 #include "irq_kern.h"
  23 #include "irq_user.h"
  24 #include "kern_util.h"
  25 #include "mconsole.h"
  26 #include "mconsole_kern.h"
  27 #include "os.h"
  28
  29 static int do_unlink_socket(struct notifier_block *notifier,
  30                             unsigned long what, void *data)
  31 {
  32         return mconsole_unlink_socket();
  33 }
  34
  35
  36 static struct notifier_block reboot_notifier = {
  37         .notifier_call          = do_unlink_socket,
  38         .priority               = 0,
  39 };
  40
  41 /* Safe without explicit locking for now.  Tasklets provide their own
  42  * locking, and the interrupt handler is safe because it can't interrupt
  43  * itself and it can only happen on CPU 0.
  44  */
  45
  46 static LIST_HEAD(mc_requests);
  47
  48 static void mc_work_proc(struct work_struct *unused)
  49 {
  50         struct mconsole_entry *req;
  51         unsigned long flags;
  52
  53         while (!list_empty(&mc_requests)) {
  54                 local_irq_save(flags);
  55                 req = list_entry(mc_requests.next, struct mconsole_entry, list);
  56                 list_del(&req->list);
  57                 local_irq_restore(flags);
  58                 req->request.cmd->handler(&req->request);
  59                 kfree(req);
  60         }
  61 }
  62
  63 static DECLARE_WORK(mconsole_work, mc_work_proc);
  64
  65 static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
  66 {
  67         /* long to avoid size mismatch warnings from gcc */
  68         long fd;
  69         struct mconsole_entry *new;
  70         static struct mc_request req;   /* that's OK */
  71
  72         fd = (long) dev_id;
  73         while (mconsole_get_request(fd, &req)) {
  74                 if (req.cmd->context == MCONSOLE_INTR)
  75                         (*req.cmd->handler)(&req);
  76                 else {
  77                         new = kmalloc(sizeof(*new), GFP_NOWAIT);
  78                         if (new == NULL)
  79                                 mconsole_reply(&req, "Out of memory", 1, 0);
  80                         else {
  81                                 new->request = req;
  82                                 new->request.regs = get_irq_regs()->regs;
  83                                 list_add(&new->list, &mc_requests);
  84                         }
  85                 }
  86         }
  87         if (!list_empty(&mc_requests))
  88                 schedule_work(&mconsole_work);
  89         reactivate_fd(fd, MCONSOLE_IRQ);
  90         return IRQ_HANDLED;
  91 }
  92
  93 void mconsole_version(struct mc_request *req)
  94 {
  95         char version[256];
  96
  97         sprintf(version, "%s %s %s %s %s", utsname()->sysname,
  98                 utsname()->nodename, utsname()->release, utsname()->version,
  99                 utsname()->machine);
 100         mconsole_reply(req, version, 0, 0);
 101 }
 102
 103 void mconsole_log(struct mc_request *req)
 104 {
 105         int len;
 106         char *ptr = req->request.data;
 107
 108         ptr += strlen("log ");
 109
 110         len = req->len - (ptr - req->request.data);
 111         printk(KERN_WARNING "%.*s", len, ptr);
 112         mconsole_reply(req, "", 0, 0);
 113 }
 114
 115 /* This is a more convoluted version of mconsole_proc, which has some stability
 116  * problems; however, we need it fixed, because it is expected that UML users
 117  * mount HPPFS instead of procfs on /proc. And we want mconsole_proc to still
 118  * show the real procfs content, not the ones from hppfs.*/
 119 #if 0
 120 void mconsole_proc(struct mc_request *req)
 121 {
 122         struct nameidata nd;
 123         struct file_system_type *proc;
 124         struct super_block *super;
 125         struct file *file;
 126         int n, err;
 127         char *ptr = req->request.data, *buf;
 128
 129         ptr += strlen("proc");
 130         while (isspace(*ptr)) ptr++;
 131
 132         proc = get_fs_type("proc");
 133         if (proc == NULL) {
 134                 mconsole_reply(req, "procfs not registered", 1, 0);
 135                 goto out;
 136         }
 137
 138         super = (*proc->get_sb)(proc, 0, NULL, NULL);
 139         put_filesystem(proc);
 140         if (super == NULL) {
 141                 mconsole_reply(req, "Failed to get procfs superblock", 1, 0);
 142                 goto out;
 143         }
 144         up_write(&super->s_umount);
 145
 146         nd.dentry = super->s_root;
 147         nd.mnt = NULL;
 148         nd.flags = O_RDONLY + 1;
 149         nd.last_type = LAST_ROOT;
 150
 151         /* START: it was experienced that the stability problems are closed
 152          * if commenting out these two calls + the below read cycle. To
 153          * make UML crash again, it was enough to readd either one.*/
 154         err = link_path_walk(ptr, &nd);
 155         if (err) {
 156                 mconsole_reply(req, "Failed to look up file", 1, 0);
 157                 goto out_kill;
 158         }
 159
 160         file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
 161         if (IS_ERR(file)) {
 162                 mconsole_reply(req, "Failed to open file", 1, 0);
 163                 goto out_kill;
 164         }
 165         /*END*/
 166
 167         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 168         if (buf == NULL) {
 169                 mconsole_reply(req, "Failed to allocate buffer", 1, 0);
 170                 goto out_fput;
 171         }
 172
 173         if ((file->f_op != NULL) && (file->f_op->read != NULL)) {
 174                 do {
 175                         n = (*file->f_op->read)(file, buf, PAGE_SIZE - 1,
 176                                                 &file->f_pos);
 177                         if (n >= 0) {
 178                                 buf[n] = '\0';
 179                                 mconsole_reply(req, buf, 0, (n > 0));
 180                         }
 181                         else {
 182                                 mconsole_reply(req, "Read of file failed",
 183                                                1, 0);
 184                                 goto out_free;
 185                         }
 186                 } while (n > 0);
 187         }
 188         else mconsole_reply(req, "", 0, 0);
 189
 190  out_free:
 191         kfree(buf);
 192  out_fput:
 193         fput(file);
 194  out_kill:
 195         deactivate_super(super);
 196  out: ;
 197 }
 198 #endif
 199
 200 void mconsole_proc(struct mc_request *req)
 201 {
 202         char path[64];
 203         char *buf;
 204         int len;
 205         int fd;
 206         int first_chunk = 1;
 207         char *ptr = req->request.data;
 208
 209         ptr += strlen("proc");
 210         while (isspace(*ptr))
 211                 ptr++;
 212         snprintf(path, sizeof(path), "/proc/%s", ptr);
 213
 214         fd = sys_open(path, 0, 0);
 215         if (fd < 0) {
 216                 mconsole_reply(req, "Failed to open file", 1, 0);
 217                 printk(KERN_ERR "open %s: %d\n",path,fd);
 218                 goto out;
 219         }
 220
 221         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 222         if (buf == NULL) {
 223                 mconsole_reply(req, "Failed to allocate buffer", 1, 0);
 224                 goto out_close;
 225         }
 226
 227         for (;;) {
 228                 len = sys_read(fd, buf, PAGE_SIZE-1);
 229                 if (len < 0) {
 230                         mconsole_reply(req, "Read of file failed", 1, 0);
 231                         goto out_free;
 232                 }
 233                 /* Begin the file content on his own line. */
 234                 if (first_chunk) {
 235                         mconsole_reply(req, "\n", 0, 1);
 236                         first_chunk = 0;
 237                 }
 238                 if (len == PAGE_SIZE-1) {
 239                         buf[len] = '\0';
 240                         mconsole_reply(req, buf, 0, 1);
 241                 } else {
 242                         buf[len] = '\0';
 243                         mconsole_reply(req, buf, 0, 0);
 244                         break;
 245                 }
 246         }
 247
 248  out_free:
 249         kfree(buf);
 250  out_close:
 251         sys_close(fd);
 252  out:
 253         /* nothing */;
 254 }
 255
 256 #define UML_MCONSOLE_HELPTEXT \
 257 "Commands: \n\
 258     version - Get kernel version \n\
 259     help - Print this message \n\
 260     halt - Halt UML \n\
 261     reboot - Reboot UML \n\
 262     config <dev>=<config> - Add a new device to UML;  \n\
 263         same syntax as command line \n\
 264     config <dev> - Query the configuration of a device \n\
 265     remove <dev> - Remove a device from UML \n\
 266     sysrq <letter> - Performs the SysRq action controlled by the letter \n\
 267     cad - invoke the Ctrl-Alt-Del handler \n\
 268     stop - pause the UML; it will do nothing until it receives a 'go' \n\
 269     go - continue the UML after a 'stop' \n\
 270     log <string> - make UML enter <string> into the kernel log\n\
 271     proc <file> - returns the contents of the UML's /proc/<file>\n\
 272     stack <pid> - returns the stack of the specified pid\n\
 273 "
 274
 275 void mconsole_help(struct mc_request *req)
 276 {
 277         mconsole_reply(req, UML_MCONSOLE_HELPTEXT, 0, 0);
 278 }
 279
 280 void mconsole_halt(struct mc_request *req)
 281 {
 282         mconsole_reply(req, "", 0, 0);
 283         machine_halt();
 284 }
 285
 286 void mconsole_reboot(struct mc_request *req)
 287 {
 288         mconsole_reply(req, "", 0, 0);
 289         machine_restart(NULL);
 290 }
 291
 292 void mconsole_cad(struct mc_request *req)
 293 {
 294         mconsole_reply(req, "", 0, 0);
 295         ctrl_alt_del();
 296 }
 297
 298 void mconsole_go(struct mc_request *req)
 299 {
 300         mconsole_reply(req, "Not stopped", 1, 0);
 301 }
 302
 303 void mconsole_stop(struct mc_request *req)
 304 {
 305         deactivate_fd(req->originating_fd, MCONSOLE_IRQ);
 306         os_set_fd_block(req->originating_fd, 1);
 307         mconsole_reply(req, "stopped", 0, 0);
 308         while (mconsole_get_request(req->originating_fd, req)) {
 309                 if (req->cmd->handler == mconsole_go)
 310                         break;
 311                 if (req->cmd->handler == mconsole_stop) {
 312                         mconsole_reply(req, "Already stopped", 1, 0);
 313                         continue;
 314                 }
 315                 if (req->cmd->handler == mconsole_sysrq) {
 316                         struct pt_regs *old_regs;
 317                         old_regs = set_irq_regs((struct pt_regs *)&req->regs);
 318                         mconsole_sysrq(req);
 319                         set_irq_regs(old_regs);
 320                         continue;
 321                 }
 322                 (*req->cmd->handler)(req);
 323         }
 324         os_set_fd_block(req->originating_fd, 0);
 325         reactivate_fd(req->originating_fd, MCONSOLE_IRQ);
 326         mconsole_reply(req, "", 0, 0);
 327 }
 328
 329 static DEFINE_SPINLOCK(mc_devices_lock);
 330 static LIST_HEAD(mconsole_devices);
 331
 332 void mconsole_register_dev(struct mc_device *new)
 333 {
 334         spin_lock(&mc_devices_lock);
 335         BUG_ON(!list_empty(&new->list));
 336         list_add(&new->list, &mconsole_devices);
 337         spin_unlock(&mc_devices_lock);
 338 }
 339
 340 static struct mc_device *mconsole_find_dev(char *name)
 341 {
 342         struct list_head *ele;
 343         struct mc_device *dev;
 344
 345         list_for_each(ele, &mconsole_devices) {
 346                 dev = list_entry(ele, struct mc_device, list);
 347                 if (!strncmp(name, dev->name, strlen(dev->name)))
 348                         return dev;
 349         }
 350         return NULL;
 351 }
 352
 353 #define UNPLUGGED_PER_PAGE \
 354         ((PAGE_SIZE - sizeof(struct list_head)) / sizeof(unsigned long))
 355
 356 struct unplugged_pages {
 357         struct list_head list;
 358         void *pages[UNPLUGGED_PER_PAGE];
 359 };
 360
 361 static DECLARE_MUTEX(plug_mem_mutex);
 362 static unsigned long long unplugged_pages_count = 0;
 363 static LIST_HEAD(unplugged_pages);
 364 static int unplug_index = UNPLUGGED_PER_PAGE;
 365
 366 static int mem_config(char *str, char **error_out)
 367 {
 368         unsigned long long diff;
 369         int err = -EINVAL, i, add;
 370         char *ret;
 371
 372         if (str[0] != '=') {
 373                 *error_out = "Expected '=' after 'mem'";
 374                 goto out;
 375         }
 376
 377         str++;
 378         if (str[0] == '-')
 379                 add = 0;
 380         else if (str[0] == '+') {
 381                 add = 1;
 382         }
 383         else {
 384                 *error_out = "Expected increment to start with '-' or '+'";
 385                 goto out;
 386         }
 387
 388         str++;
 389         diff = memparse(str, &ret);
 390         if (*ret != '\0') {
 391                 *error_out = "Failed to parse memory increment";
 392                 goto out;
 393         }
 394
 395         diff /= PAGE_SIZE;
 396
 397         down(&plug_mem_mutex);
 398         for (i = 0; i < diff; i++) {
 399                 struct unplugged_pages *unplugged;
 400                 void *addr;
 401
 402                 if (add) {
 403                         if (list_empty(&unplugged_pages))
 404                                 break;
 405
 406                         unplugged = list_entry(unplugged_pages.next,
 407                                                struct unplugged_pages, list);
 408                         if (unplug_index > 0)
 409                                 addr = unplugged->pages[--unplug_index];
 410                         else {
 411                                 list_del(&unplugged->list);
 412                                 addr = unplugged;
 413                                 unplug_index = UNPLUGGED_PER_PAGE;
 414                         }
 415
 416                         free_page((unsigned long) addr);
 417                         unplugged_pages_count--;
 418                 }
 419                 else {
 420                         struct page *page;
 421
 422                         page = alloc_page(GFP_ATOMIC);
 423                         if (page == NULL)
 424                                 break;
 425
 426                         unplugged = page_address(page);
 427                         if (unplug_index == UNPLUGGED_PER_PAGE) {
 428                                 list_add(&unplugged->list, &unplugged_pages);
 429                                 unplug_index = 0;
 430                         }
 431                         else {
 432                                 struct list_head *entry = unplugged_pages.next;
 433                                 addr = unplugged;
 434
 435                                 unplugged = list_entry(entry,
 436                                                        struct unplugged_pages,
 437                                                        list);
 438                                 err = os_drop_memory(addr, PAGE_SIZE);
 439                                 if (err) {
 440                                         printk(KERN_ERR "Failed to release "
 441                                                "memory - errno = %d\n", err);
 442                                         *error_out = "Failed to release memory";
 443                                         goto out_unlock;
 444                                 }
 445                                 unplugged->pages[unplug_index++] = addr;
 446                         }
 447
 448                         unplugged_pages_count++;
 449                 }
 450         }
 451
 452         err = 0;
 453 out_unlock:
 454         up(&plug_mem_mutex);
 455 out:
 456         return err;
 457 }
 458
 459 static int mem_get_config(char *name, char *str, int size, char **error_out)
 460 {
 461         char buf[sizeof("18446744073709551615")];
 462         int len = 0;
 463
 464         sprintf(buf, "%ld", uml_physmem);
 465         CONFIG_CHUNK(str, size, len, buf, 1);
 466
 467         return len;
 468 }
 469
 470 static int mem_id(char **str, int *start_out, int *end_out)
 471 {
 472         *start_out = 0;
 473         *end_out = 0;
 474
 475         return 0;
 476 }
 477
 478 static int mem_remove(int n, char **error_out)
 479 {
 480         *error_out = "Memory doesn't support the remove operation";
 481         return -EBUSY;
 482 }
 483
 484 static struct mc_device mem_mc = {
 485         .list           = LIST_HEAD_INIT(mem_mc.list),
 486         .name           = "mem",
 487         .config         = mem_config,
 488         .get_config     = mem_get_config,
 489         .id             = mem_id,
 490         .remove         = mem_remove,
 491 };
 492
 493 static int __init mem_mc_init(void)
 494 {
 495         if (can_drop_memory())
 496                 mconsole_register_dev(&mem_mc);
 497         else printk(KERN_ERR "Can't release memory to the host - memory "
 498                     "hotplug won't be supported\n");
 499         return 0;
 500 }
 501
 502 __initcall(mem_mc_init);
 503
 504 #define CONFIG_BUF_SIZE 64
 505
 506 static void mconsole_get_config(int (*get_config)(char *, char *, int,
 507                                                   char **),
 508                                 struct mc_request *req, char *name)
 509 {
 510         char default_buf[CONFIG_BUF_SIZE], *error, *buf;
 511         int n, size;
 512
 513         if (get_config == NULL) {
 514                 mconsole_reply(req, "No get_config routine defined", 1, 0);
 515                 return;
 516         }
 517
 518         error = NULL;
 519         size = ARRAY_SIZE(default_buf);
 520         buf = default_buf;
 521
 522         while (1) {
 523                 n = (*get_config)(name, buf, size, &error);
 524                 if (error != NULL) {
 525                         mconsole_reply(req, error, 1, 0);
 526                         goto out;
 527                 }
 528
 529                 if (n <= size) {
 530                         mconsole_reply(req, buf, 0, 0);
 531                         goto out;
 532                 }
 533
 534                 if (buf != default_buf)
 535                         kfree(buf);
 536
 537                 size = n;
 538                 buf = kmalloc(size, GFP_KERNEL);
 539                 if (buf == NULL) {
 540                         mconsole_reply(req, "Failed to allocate buffer", 1, 0);
 541                         return;
 542                 }
 543         }
 544  out:
 545         if (buf != default_buf)
 546                 kfree(buf);
 547 }
 548
 549 void mconsole_config(struct mc_request *req)
 550 {
 551         struct mc_device *dev;
 552         char *ptr = req->request.data, *name, *error_string = "";
 553         int err;
 554
 555         ptr += strlen("config");
 556         while (isspace(*ptr))
 557                 ptr++;
 558         dev = mconsole_find_dev(ptr);
 559         if (dev == NULL) {
 560                 mconsole_reply(req, "Bad configuration option", 1, 0);
 561                 return;
 562         }
 563
 564         name = &ptr[strlen(dev->name)];
 565         ptr = name;
 566         while ((*ptr != '=') && (*ptr != '\0'))
 567                 ptr++;
 568
 569         if (*ptr == '=') {
 570                 err = (*dev->config)(name, &error_string);
 571                 mconsole_reply(req, error_string, err, 0);
 572         }
 573         else mconsole_get_config(dev->get_config, req, name);
 574 }
 575
 576 void mconsole_remove(struct mc_request *req)
 577 {
 578         struct mc_device *dev;
 579         char *ptr = req->request.data, *err_msg = "";
 580         char error[256];
 581         int err, start, end, n;
 582
 583         ptr += strlen("remove");
 584         while (isspace(*ptr)) ptr++;
 585         dev = mconsole_find_dev(ptr);
 586         if (dev == NULL) {
 587                 mconsole_reply(req, "Bad remove option", 1, 0);
 588                 return;
 589         }
 590
 591         ptr = &ptr[strlen(dev->name)];
 592
 593         err = 1;
 594         n = (*dev->id)(&ptr, &start, &end);
 595         if (n < 0) {
 596                 err_msg = "Couldn't parse device number";
 597                 goto out;
 598         }
 599         else if ((n < start) || (n > end)) {
 600                 sprintf(error, "Invalid device number - must be between "
 601                         "%d and %d", start, end);
 602                 err_msg = error;
 603                 goto out;
 604         }
 605
 606         err_msg = NULL;
 607         err = (*dev->remove)(n, &err_msg);
 608         switch(err) {
 609         case 0:
 610                 err_msg = "";
 611                 break;
 612         case -ENODEV:
 613                 if (err_msg == NULL)
 614                         err_msg = "Device doesn't exist";
 615                 break;
 616         case -EBUSY:
 617                 if (err_msg == NULL)
 618                         err_msg = "Device is currently open";
 619                 break;
 620         default:
 621                 break;
 622         }
 623 out:
 624         mconsole_reply(req, err_msg, err, 0);
 625 }
 626
 627 struct mconsole_output {
 628         struct list_head list;
 629         struct mc_request *req;
 630 };
 631
 632 static DEFINE_SPINLOCK(client_lock);
 633 static LIST_HEAD(clients);
 634 static char console_buf[MCONSOLE_MAX_DATA];
 635
 636 static void console_write(struct console *console, const char *string,
 637                           unsigned int len)
 638 {
 639         struct list_head *ele;
 640         int n;
 641
 642         if (list_empty(&clients))
 643                 return;
 644
 645         while (len > 0) {
 646                 n = min((size_t) len, ARRAY_SIZE(console_buf));
 647                 strncpy(console_buf, string, n);
 648                 string += n;
 649                 len -= n;
 650
 651                 list_for_each(ele, &clients) {
 652                         struct mconsole_output *entry;
 653
 654                         entry = list_entry(ele, struct mconsole_output, list);
 655                         mconsole_reply_len(entry->req, console_buf, n, 0, 1);
 656                 }
 657         }
 658 }
 659
 660 static struct console mc_console = { .name      = "mc",
 661                                      .write     = console_write,
 662                                      .flags     = CON_ENABLED,
 663                                      .index     = -1 };
 664
 665 static int mc_add_console(void)
 666 {
 667         register_console(&mc_console);
 668         return 0;
 669 }
 670
 671 late_initcall(mc_add_console);
 672
 673 static void with_console(struct mc_request *req, void (*proc)(void *),
 674                          void *arg)
 675 {
 676         struct mconsole_output entry;
 677         unsigned long flags;
 678
 679         entry.req = req;
 680         spin_lock_irqsave(&client_lock, flags);
 681         list_add(&entry.list, &clients);
 682         spin_unlock_irqrestore(&client_lock, flags);
 683
 684         (*proc)(arg);
 685
 686         mconsole_reply_len(req, "", 0, 0, 0);
 687
 688         spin_lock_irqsave(&client_lock, flags);
 689         list_del(&entry.list);
 690         spin_unlock_irqrestore(&client_lock, flags);
 691 }
 692
 693 #ifdef CONFIG_MAGIC_SYSRQ
 694
 695 #include <linux/sysrq.h>
 696
 697 static void sysrq_proc(void *arg)
 698 {
 699         char *op = arg;
 700         handle_sysrq(*op, NULL);
 701 }
 702
 703 void mconsole_sysrq(struct mc_request *req)
 704 {
 705         char *ptr = req->request.data;
 706
 707         ptr += strlen("sysrq");
 708         while (isspace(*ptr)) ptr++;
 709
 710         /*
 711          * With 'b', the system will shut down without a chance to reply,
 712          * so in this case, we reply first.
 713          */
 714         if (*ptr == 'b')
 715                 mconsole_reply(req, "", 0, 0);
 716
 717         with_console(req, sysrq_proc, ptr);
 718 }
 719 #else
 720 void mconsole_sysrq(struct mc_request *req)
 721 {
 722         mconsole_reply(req, "Sysrq not compiled in", 1, 0);
 723 }
 724 #endif
 725
 726 static void stack_proc(void *arg)
 727 {
 728         struct task_struct *from = current, *to = arg;
 729
 730         to->thread.saved_task = from;
 731         switch_to(from, to, from);
 732 }
 733
 734 /*
 735  * Mconsole stack trace
 736  *  Added by Allan Graves, Jeff Dike
 737  *  Dumps a stacks registers to the linux console.
 738  *  Usage stack <pid>.
 739  */
 740 void mconsole_stack(struct mc_request *req)
 741 {
 742         char *ptr = req->request.data;
 743         int pid_requested= -1;
 744         struct task_struct *from = NULL;
 745         struct task_struct *to = NULL;
 746
 747         /*
 748          * Would be nice:
 749          * 1) Send showregs output to mconsole.
 750          * 2) Add a way to stack dump all pids.
 751          */
 752
 753         ptr += strlen("stack");
 754         while (isspace(*ptr))
 755                 ptr++;
 756
 757         /*
 758          * Should really check for multiple pids or reject bad args here
 759          */
 760         /* What do the arguments in mconsole_reply mean? */
 761         if (sscanf(ptr, "%d", &pid_requested) == 0) {
 762                 mconsole_reply(req, "Please specify a pid", 1, 0);
 763                 return;
 764         }
 765
 766         from = current;
 767
 768         to = find_task_by_pid(pid_requested);
 769         if ((to == NULL) || (pid_requested == 0)) {
 770                 mconsole_reply(req, "Couldn't find that pid", 1, 0);
 771                 return;
 772         }
 773         with_console(req, stack_proc, to);
 774 }
 775
 776 /*
 777  * Changed by mconsole_setup, which is __setup, and called before SMP is
 778  * active.
 779  */
 780 static char *notify_socket = NULL;
 781
 782 static int __init mconsole_init(void)
 783 {
 784         /* long to avoid size mismatch warnings from gcc */
 785         long sock;
 786         int err;
 787         char file[256];
 788
 789         if (umid_file_name("mconsole", file, sizeof(file)))
 790                 return -1;
 791         snprintf(mconsole_socket_name, sizeof(file), "%s", file);
 792
 793         sock = os_create_unix_socket(file, sizeof(file), 1);
 794         if (sock < 0) {
 795                 printk(KERN_ERR "Failed to initialize management console\n");
 796                 return 1;
 797         }
 798
 799         register_reboot_notifier(&reboot_notifier);
 800
 801         err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt,
 802                              IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
 803                              "mconsole", (void *)sock);
 804         if (err) {
 805                 printk(KERN_ERR "Failed to get IRQ for management console\n");
 806                 return 1;
 807         }
 808
 809         if (notify_socket != NULL) {
 810                 notify_socket = kstrdup(notify_socket, GFP_KERNEL);
 811                 if (notify_socket != NULL)
 812                         mconsole_notify(notify_socket, MCONSOLE_SOCKET,
 813                                         mconsole_socket_name,
 814                                         strlen(mconsole_socket_name) + 1);
 815                 else printk(KERN_ERR "mconsole_setup failed to strdup "
 816                             "string\n");
 817         }
 818
 819         printk(KERN_INFO "mconsole (version %d) initialized on %s\n",
 820                MCONSOLE_VERSION, mconsole_socket_name);
 821         return 0;
 822 }
 823
 824 __initcall(mconsole_init);
 825
 826 static int write_proc_mconsole(struct file *file, const char __user *buffer,
 827                                unsigned long count, void *data)
 828 {
 829         char *buf;
 830
 831         buf = kmalloc(count + 1, GFP_KERNEL);
 832         if (buf == NULL)
 833                 return -ENOMEM;
 834
 835         if (copy_from_user(buf, buffer, count)) {
 836                 count = -EFAULT;
 837                 goto out;
 838         }
 839
 840         buf[count] = '\0';
 841
 842         mconsole_notify(notify_socket, MCONSOLE_USER_NOTIFY, buf, count);
 843  out:
 844         kfree(buf);
 845         return count;
 846 }
 847
 848 static int create_proc_mconsole(void)
 849 {
 850         struct proc_dir_entry *ent;
 851
 852         if (notify_socket == NULL)
 853                 return 0;
 854
 855         ent = create_proc_entry("mconsole", S_IFREG | 0200, NULL);
 856         if (ent == NULL) {
 857                 printk(KERN_INFO "create_proc_mconsole : create_proc_entry "
 858                        "failed\n");
 859                 return 0;
 860         }
 861
 862         ent->read_proc = NULL;
 863         ent->write_proc = write_proc_mconsole;
 864         return 0;
 865 }
 866
 867 static DEFINE_SPINLOCK(notify_spinlock);
 868
 869 void lock_notify(void)
 870 {
 871         spin_lock(&notify_spinlock);
 872 }
 873
 874 void unlock_notify(void)
 875 {
 876         spin_unlock(&notify_spinlock);
 877 }
 878
 879 __initcall(create_proc_mconsole);
 880
 881 #define NOTIFY "notify:"
 882
 883 static int mconsole_setup(char *str)
 884 {
 885         if (!strncmp(str, NOTIFY, strlen(NOTIFY))) {
 886                 str += strlen(NOTIFY);
 887                 notify_socket = str;
 888         }
 889         else printk(KERN_ERR "mconsole_setup : Unknown option - '%s'\n", str);
 890         return 1;
 891 }
 892
 893 __setup("mconsole=", mconsole_setup);
 894
 895 __uml_help(mconsole_setup,
 896 "mconsole=notify:<socket>\n"
 897 "    Requests that the mconsole driver send a message to the named Unix\n"
 898 "    socket containing the name of the mconsole socket.  This also serves\n"
 899 "    to notify outside processes when UML has booted far enough to respond\n"
 900 "    to mconsole requests.\n\n"
 901 );
 902
 903 static int notify_panic(struct notifier_block *self, unsigned long unused1,
 904                         void *ptr)
 905 {
 906         char *message = ptr;
 907
 908         if (notify_socket == NULL)
 909                 return 0;
 910
 911         mconsole_notify(notify_socket, MCONSOLE_PANIC, message,
 912                         strlen(message) + 1);
 913         return 0;
 914 }
 915
 916 static struct notifier_block panic_exit_notifier = {
 917         .notifier_call          = notify_panic,
 918         .next                   = NULL,
 919         .priority               = 1
 920 };
 921
 922 static int add_notifier(void)
 923 {
 924         atomic_notifier_chain_register(&panic_notifier_list,
 925                         &panic_exit_notifier);
 926         return 0;
 927 }
 928
 929 __initcall(add_notifier);
 930
 931 char *mconsole_notify_socket(void)
 932 {
 933         return notify_socket;
 934 }
 935
 936 EXPORT_SYMBOL(mconsole_notify_socket);