arch/um/drivers/mconsole_kern.c

   1 /*
   2  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
   3  * Copyright (C) 2001 - 2008 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/socket.h>
  20 #include <linux/un.h>
  21 #include <linux/workqueue.h>
  22 #include <linux/mutex.h>
  23 #include <asm/uaccess.h>
  24
  25 #include "init.h"
  26 #include "irq_kern.h"
  27 #include "irq_user.h"
  28 #include "kern_util.h"
  29 #include "mconsole.h"
  30 #include "mconsole_kern.h"
  31 #include "os.h"
  32
  33 static int do_unlink_socket(struct notifier_block *notifier,
  34                             unsigned long what, void *data)
  35 {
  36         return mconsole_unlink_socket();
  37 }
  38
  39
  40 static struct notifier_block reboot_notifier = {
  41         .notifier_call          = do_unlink_socket,
  42         .priority               = 0,
  43 };
  44
  45 /* Safe without explicit locking for now.  Tasklets provide their own
  46  * locking, and the interrupt handler is safe because it can't interrupt
  47  * itself and it can only happen on CPU 0.
  48  */
  49
  50 static LIST_HEAD(mc_requests);
  51
  52 static void mc_work_proc(struct work_struct *unused)
  53 {
  54         struct mconsole_entry *req;
  55         unsigned long flags;
  56
  57         while (!list_empty(&mc_requests)) {
  58                 local_irq_save(flags);
  59                 req = list_entry(mc_requests.next, struct mconsole_entry, list);
  60                 list_del(&req->list);
  61                 local_irq_restore(flags);
  62                 req->request.cmd->handler(&req->request);
  63                 kfree(req);
  64         }
  65 }
  66
  67 static DECLARE_WORK(mconsole_work, mc_work_proc);
  68
  69 static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
  70 {
  71         /* long to avoid size mismatch warnings from gcc */
  72         long fd;
  73         struct mconsole_entry *new;
  74         static struct mc_request req;   /* that's OK */
  75
  76         fd = (long) dev_id;
  77         while (mconsole_get_request(fd, &req)) {
  78                 if (req.cmd->context == MCONSOLE_INTR)
  79                         (*req.cmd->handler)(&req);
  80                 else {
  81                         new = kmalloc(sizeof(*new), GFP_NOWAIT);
  82                         if (new == NULL)
  83                                 mconsole_reply(&req, "Out of memory", 1, 0);
  84                         else {
  85                                 new->request = req;
  86                                 new->request.regs = get_irq_regs()->regs;
  87                                 list_add(&new->list, &mc_requests);
  88                         }
  89                 }
  90         }
  91         if (!list_empty(&mc_requests))
  92                 schedule_work(&mconsole_work);
  93         reactivate_fd(fd, MCONSOLE_IRQ);
  94         return IRQ_HANDLED;
  95 }
  96
  97 void mconsole_version(struct mc_request *req)
  98 {
  99         char version[256];
 100
 101         sprintf(version, "%s %s %s %s %s", utsname()->sysname,
 102                 utsname()->nodename, utsname()->release, utsname()->version,
 103                 utsname()->machine);
 104         mconsole_reply(req, version, 0, 0);
 105 }
 106
 107 void mconsole_log(struct mc_request *req)
 108 {
 109         int len;
 110         char *ptr = req->request.data;
 111
 112         ptr += strlen("log ");
 113
 114         len = req->len - (ptr - req->request.data);
 115         printk(KERN_WARNING "%.*s", len, ptr);
 116         mconsole_reply(req, "", 0, 0);
 117 }
 118
 119 /* This is a more convoluted version of mconsole_proc, which has some stability
 120  * problems; however, we need it fixed, because it is expected that UML users
 121  * mount HPPFS instead of procfs on /proc. And we want mconsole_proc to still
 122  * show the real procfs content, not the ones from hppfs.*/
 123 #if 0
 124 void mconsole_proc(struct mc_request *req)
 125 {
 126         struct nameidata nd;
 127         struct file_system_type *proc;
 128         struct super_block *super;
 129         struct file *file;
 130         int n, err;
 131         char *ptr = req->request.data, *buf;
 132
 133         ptr += strlen("proc");
 134         while (isspace(*ptr)) ptr++;
 135
 136         proc = get_fs_type("proc");
 137         if (proc == NULL) {
 138                 mconsole_reply(req, "procfs not registered", 1, 0);
 139                 goto out;
 140         }
 141
 142         super = (*proc->get_sb)(proc, 0, NULL, NULL);
 143         put_filesystem(proc);
 144         if (super == NULL) {
 145                 mconsole_reply(req, "Failed to get procfs superblock", 1, 0);
 146                 goto out;
 147         }
 148         up_write(&super->s_umount);
 149
 150         nd.path.dentry = super->s_root;
 151         nd.path.mnt = NULL;
 152         nd.flags = O_RDONLY + 1;
 153         nd.last_type = LAST_ROOT;
 154
 155         /* START: it was experienced that the stability problems are closed
 156          * if commenting out these two calls + the below read cycle. To
 157          * make UML crash again, it was enough to readd either one.*/
 158         err = link_path_walk(ptr, &nd);
 159         if (err) {
 160                 mconsole_reply(req, "Failed to look up file", 1, 0);
 161                 goto out_kill;
 162         }
 163
 164         file = dentry_open(nd.path.dentry, nd.path.mnt, O_RDONLY);
 165         if (IS_ERR(file)) {
 166                 mconsole_reply(req, "Failed to open file", 1, 0);
 167                 goto out_kill;
 168         }
 169         /*END*/
 170
 171         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 172         if (buf == NULL) {
 173                 mconsole_reply(req, "Failed to allocate buffer", 1, 0);
 174                 goto out_fput;
 175         }
 176
 177         if ((file->f_op != NULL) && (file->f_op->read != NULL)) {
 178                 do {
 179                         n = (*file->f_op->read)(file, buf, PAGE_SIZE - 1,
 180                                                 &file->f_pos);
 181                         if (n >= 0) {
 182                                 buf[n] = '\0';
 183                                 mconsole_reply(req, buf, 0, (n > 0));
 184                         }
 185                         else {
 186                                 mconsole_reply(req, "Read of file failed",
 187                                                1, 0);
 188                                 goto out_free;
 189                         }
 190                 } while (n > 0);
 191         }
 192         else mconsole_reply(req, "", 0, 0);
 193
 194  out_free:
 195         kfree(buf);
 196  out_fput:
 197         fput(file);
 198  out_kill:
 199         deactivate_super(super);
 200  out: ;
 201 }
 202 #endif
 203
 204 void mconsole_proc(struct mc_request *req)
 205 {
 206         char path[64];
 207         char *buf;
 208         int len;
 209         int fd;
 210         int first_chunk = 1;
 211         char *ptr = req->request.data;
 212
 213         ptr += strlen("proc");
 214         while (isspace(*ptr))
 215                 ptr++;
 216         snprintf(path, sizeof(path), "/proc/%s", ptr);
 217
 218         fd = sys_open(path, 0, 0);
 219         if (fd < 0) {
 220                 mconsole_reply(req, "Failed to open file", 1, 0);
 221                 printk(KERN_ERR "open %s: %d\n",path,fd);
 222                 goto out;
 223         }
 224
 225         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 226         if (buf == NULL) {
 227                 mconsole_reply(req, "Failed to allocate buffer", 1, 0);
 228                 goto out_close;
 229         }
 230
 231         for (;;) {
 232                 len = sys_read(fd, buf, PAGE_SIZE-1);
 233                 if (len < 0) {
 234                         mconsole_reply(req, "Read of file failed", 1, 0);
 235                         goto out_free;
 236                 }
 237                 /* Begin the file content on his own line. */
 238                 if (first_chunk) {
 239                         mconsole_reply(req, "\n", 0, 1);
 240                         first_chunk = 0;
 241                 }
 242                 if (len == PAGE_SIZE-1) {
 243                         buf[len] = '\0';
 244                         mconsole_reply(req, buf, 0, 1);
 245                 } else {
 246                         buf[len] = '\0';
 247                         mconsole_reply(req, buf, 0, 0);
 248                         break;
 249                 }
 250         }
 251
 252  out_free:
 253         kfree(buf);
 254  out_close:
 255         sys_close(fd);
 256  out:
 257         /* nothing */;
 258 }
 259
 260 #define UML_MCONSOLE_HELPTEXT \
 261 "Commands: \n\
 262     version - Get kernel version \n\
 263     help - Print this message \n\
 264     halt - Halt UML \n\
 265     reboot - Reboot UML \n\
 266     config <dev>=<config> - Add a new device to UML;  \n\
 267         same syntax as command line \n\
 268     config <dev> - Query the configuration of a device \n\
 269     remove <dev> - Remove a device from UML \n\
 270     sysrq <letter> - Performs the SysRq action controlled by the letter \n\
 271     cad - invoke the Ctrl-Alt-Del handler \n\
 272     stop - pause the UML; it will do nothing until it receives a 'go' \n\
 273     go - continue the UML after a 'stop' \n\
 274     log <string> - make UML enter <string> into the kernel log\n\
 275     proc <file> - returns the contents of the UML's /proc/<file>\n\
 276     stack <pid> - returns the stack of the specified pid\n\
 277 "
 278
 279 void mconsole_help(struct mc_request *req)
 280 {
 281         mconsole_reply(req, UML_MCONSOLE_HELPTEXT, 0, 0);
 282 }
 283
 284 void mconsole_halt(struct mc_request *req)
 285 {
 286         mconsole_reply(req, "", 0, 0);
 287         machine_halt();
 288 }
 289
 290 void mconsole_reboot(struct mc_request *req)
 291 {
 292         mconsole_reply(req, "", 0, 0);
 293         machine_restart(NULL);
 294 }
 295
 296 void mconsole_cad(struct mc_request *req)
 297 {
 298         mconsole_reply(req, "", 0, 0);
 299         ctrl_alt_del();
 300 }
 301
 302 void mconsole_go(struct mc_request *req)
 303 {
 304         mconsole_reply(req, "Not stopped", 1, 0);
 305 }
 306
 307 void mconsole_stop(struct mc_request *req)
 308 {
 309         deactivate_fd(req->originating_fd, MCONSOLE_IRQ);
 310         os_set_fd_block(req->originating_fd, 1);
 311         mconsole_reply(req, "stopped", 0, 0);
 312         for (;;) {
 313                 if (!mconsole_get_request(req->originating_fd, req))
 314                         continue;
 315                 if (req->cmd->handler == mconsole_go)
 316                         break;
 317                 if (req->cmd->handler == mconsole_stop) {
 318                         mconsole_reply(req, "Already stopped", 1, 0);
 319                         continue;
 320                 }
 321                 if (req->cmd->handler == mconsole_sysrq) {
 322                         struct pt_regs *old_regs;
 323                         old_regs = set_irq_regs((struct pt_regs *)&req->regs);
 324                         mconsole_sysrq(req);
 325                         set_irq_regs(old_regs);
 326                         continue;
 327                 }
 328                 (*req->cmd->handler)(req);
 329         }
 330         os_set_fd_block(req->originating_fd, 0);
 331         reactivate_fd(req->originating_fd, MCONSOLE_IRQ);
 332         mconsole_reply(req, "", 0, 0);
 333 }
 334
 335 static DEFINE_SPINLOCK(mc_devices_lock);
 336 static LIST_HEAD(mconsole_devices);
 337
 338 void mconsole_register_dev(struct mc_device *new)
 339 {
 340         spin_lock(&mc_devices_lock);
 341         BUG_ON(!list_empty(&new->list));
 342         list_add(&new->list, &mconsole_devices);
 343         spin_unlock(&mc_devices_lock);
 344 }
 345
 346 static struct mc_device *mconsole_find_dev(char *name)
 347 {
 348         struct list_head *ele;
 349         struct mc_device *dev;
 350
 351         list_for_each(ele, &mconsole_devices) {
 352                 dev = list_entry(ele, struct mc_device, list);
 353                 if (!strncmp(name, dev->name, strlen(dev->name)))
 354                         return dev;
 355         }
 356         return NULL;
 357 }
 358
 359 #define UNPLUGGED_PER_PAGE \
 360         ((PAGE_SIZE - sizeof(struct list_head)) / sizeof(unsigned long))
 361
 362 struct unplugged_pages {
 363         struct list_head list;
 364         void *pages[UNPLUGGED_PER_PAGE];
 365 };
 366
 367 static DEFINE_MUTEX(plug_mem_mutex);
 368 static unsigned long long unplugged_pages_count = 0;
 369 static LIST_HEAD(unplugged_pages);
 370 static int unplug_index = UNPLUGGED_PER_PAGE;
 371
 372 static int mem_config(char *str, char **error_out)
 373 {
 374         unsigned long long diff;
 375         int err = -EINVAL, i, add;
 376         char *ret;
 377
 378         if (str[0] != '=') {
 379                 *error_out = "Expected '=' after 'mem'";
 380                 goto out;
 381         }
 382
 383         str++;
 384         if (str[0] == '-')
 385                 add = 0;
 386         else if (str[0] == '+') {
 387                 add = 1;
 388         }
 389         else {
 390                 *error_out = "Expected increment to start with '-' or '+'";
 391                 goto out;
 392         }
 393
 394         str++;
 395         diff = memparse(str, &ret);
 396         if (*ret != '\0') {
 397                 *error_out = "Failed to parse memory increment";
 398                 goto out;
 399         }
 400
 401         diff /= PAGE_SIZE;
 402
 403         mutex_lock(&plug_mem_mutex);
 404         for (i = 0; i < diff; i++) {
 405                 struct unplugged_pages *unplugged;
 406                 void *addr;
 407
 408                 if (add) {
 409                         if (list_empty(&unplugged_pages))
 410                                 break;
 411
 412                         unplugged = list_entry(unplugged_pages.next,
 413                                                struct unplugged_pages, list);
 414                         if (unplug_index > 0)
 415                                 addr = unplugged->pages[--unplug_index];
 416                         else {
 417                                 list_del(&unplugged->list);
 418                                 addr = unplugged;
 419                                 unplug_index = UNPLUGGED_PER_PAGE;
 420                         }
 421
 422                         free_page((unsigned long) addr);
 423                         unplugged_pages_count--;
 424                 }
 425                 else {
 426                         struct page *page;
 427
 428                         page = alloc_page(GFP_ATOMIC);
 429                         if (page == NULL)
 430                                 break;
 431
 432                         unplugged = page_address(page);
 433                         if (unplug_index == UNPLUGGED_PER_PAGE) {
 434                                 list_add(&unplugged->list, &unplugged_pages);
 435                                 unplug_index = 0;
 436                         }
 437                         else {
 438                                 struct list_head *entry = unplugged_pages.next;
 439                                 addr = unplugged;
 440
 441                                 unplugged = list_entry(entry,
 442                                                        struct unplugged_pages,
 443                                                        list);
 444                                 err = os_drop_memory(addr, PAGE_SIZE);
 445                                 if (err) {
 446                                         printk(KERN_ERR "Failed to release "
 447                                                "memory - errno = %d\n", err);
 448                                         *error_out = "Failed to release memory";
 449                                         goto out_unlock;
 450                                 }
 451                                 unplugged->pages[unplug_index++] = addr;
 452                         }
 453
 454                         unplugged_pages_count++;
 455                 }
 456         }
 457
 458         err = 0;
 459 out_unlock:
 460         mutex_unlock(&plug_mem_mutex);
 461 out:
 462         return err;
 463 }
 464
 465 static int mem_get_config(char *name, char *str, int size, char **error_out)
 466 {
 467         char buf[sizeof("18446744073709551615")];
 468         int len = 0;
 469
 470         sprintf(buf, "%ld", uml_physmem);
 471         CONFIG_CHUNK(str, size, len, buf, 1);
 472
 473         return len;
 474 }
 475
 476 static int mem_id(char **str, int *start_out, int *end_out)
 477 {
 478         *start_out = 0;
 479         *end_out = 0;
 480
 481         return 0;
 482 }
 483
 484 static int mem_remove(int n, char **error_out)
 485 {
 486         *error_out = "Memory doesn't support the remove operation";
 487         return -EBUSY;
 488 }
 489
 490 static struct mc_device mem_mc = {
 491         .list           = LIST_HEAD_INIT(mem_mc.list),
 492         .name           = "mem",
 493         .config         = mem_config,
 494         .get_config     = mem_get_config,
 495         .id             = mem_id,
 496         .remove         = mem_remove,
 497 };
 498
 499 static int __init mem_mc_init(void)
 500 {
 501         if (can_drop_memory())
 502                 mconsole_register_dev(&mem_mc);
 503         else printk(KERN_ERR "Can't release memory to the host - memory "
 504                     "hotplug won't be supported\n");
 505         return 0;
 506 }
 507
 508 __initcall(mem_mc_init);
 509
 510 #define CONFIG_BUF_SIZE 64
 511
 512 static void mconsole_get_config(int (*get_config)(char *, char *, int,
 513                                                   char **),
 514                                 struct mc_request *req, char *name)
 515 {
 516         char default_buf[CONFIG_BUF_SIZE], *error, *buf;
 517         int n, size;
 518
 519         if (get_config == NULL) {
 520                 mconsole_reply(req, "No get_config routine defined", 1, 0);
 521                 return;
 522         }
 523
 524         error = NULL;
 525         size = ARRAY_SIZE(default_buf);
 526         buf = default_buf;
 527
 528         while (1) {
 529                 n = (*get_config)(name, buf, size, &error);
 530                 if (error != NULL) {
 531                         mconsole_reply(req, error, 1, 0);
 532                         goto out;
 533                 }
 534
 535                 if (n <= size) {
 536                         mconsole_reply(req, buf, 0, 0);
 537                         goto out;
 538                 }
 539
 540                 if (buf != default_buf)
 541                         kfree(buf);
 542
 543                 size = n;
 544                 buf = kmalloc(size, GFP_KERNEL);
 545                 if (buf == NULL) {
 546                         mconsole_reply(req, "Failed to allocate buffer", 1, 0);
 547                         return;
 548                 }
 549         }
 550  out:
 551         if (buf != default_buf)
 552                 kfree(buf);
 553 }
 554
 555 void mconsole_config(struct mc_request *req)
 556 {
 557         struct mc_device *dev;
 558         char *ptr = req->request.data, *name, *error_string = "";
 559         int err;
 560
 561         ptr += strlen("config");
 562         while (isspace(*ptr))
 563                 ptr++;
 564         dev = mconsole_find_dev(ptr);
 565         if (dev == NULL) {
 566                 mconsole_reply(req, "Bad configuration option", 1, 0);
 567                 return;
 568         }
 569
 570         name = &ptr[strlen(dev->name)];
 571         ptr = name;
 572         while ((*ptr != '=') && (*ptr != '\0'))
 573                 ptr++;
 574
 575         if (*ptr == '=') {
 576                 err = (*dev->config)(name, &error_string);
 577                 mconsole_reply(req, error_string, err, 0);
 578         }
 579         else mconsole_get_config(dev->get_config, req, name);
 580 }
 581
 582 void mconsole_remove(struct mc_request *req)
 583 {
 584         struct mc_device *dev;
 585         char *ptr = req->request.data, *err_msg = "";
 586         char error[256];
 587         int err, start, end, n;
 588
 589         ptr += strlen("remove");
 590         while (isspace(*ptr)) ptr++;
 591         dev = mconsole_find_dev(ptr);
 592         if (dev == NULL) {
 593                 mconsole_reply(req, "Bad remove option", 1, 0);
 594                 return;
 595         }
 596
 597         ptr = &ptr[strlen(dev->name)];
 598
 599         err = 1;
 600         n = (*dev->id)(&ptr, &start, &end);
 601         if (n < 0) {
 602                 err_msg = "Couldn't parse device number";
 603                 goto out;
 604         }
 605         else if ((n < start) || (n > end)) {
 606                 sprintf(error, "Invalid device number - must be between "
 607                         "%d and %d", start, end);
 608                 err_msg = error;
 609                 goto out;
 610         }
 611
 612         err_msg = NULL;
 613         err = (*dev->remove)(n, &err_msg);
 614         switch(err) {
 615         case 0:
 616                 err_msg = "";
 617                 break;
 618         case -ENODEV:
 619                 if (err_msg == NULL)
 620                         err_msg = "Device doesn't exist";
 621                 break;
 622         case -EBUSY:
 623                 if (err_msg == NULL)
 624                         err_msg = "Device is currently open";
 625                 break;
 626         default:
 627                 break;
 628         }
 629 out:
 630         mconsole_reply(req, err_msg, err, 0);
 631 }
 632
 633 struct mconsole_output {
 634         struct list_head list;
 635         struct mc_request *req;
 636 };
 637
 638 static DEFINE_SPINLOCK(client_lock);
 639 static LIST_HEAD(clients);
 640 static char console_buf[MCONSOLE_MAX_DATA];
 641
 642 static void console_write(struct console *console, const char *string,
 643                           unsigned int len)
 644 {
 645         struct list_head *ele;
 646         int n;
 647
 648         if (list_empty(&clients))
 649                 return;
 650
 651         while (len > 0) {
 652                 n = min((size_t) len, ARRAY_SIZE(console_buf));
 653                 strncpy(console_buf, string, n);
 654                 string += n;
 655                 len -= n;
 656
 657                 list_for_each(ele, &clients) {
 658                         struct mconsole_output *entry;
 659
 660                         entry = list_entry(ele, struct mconsole_output, list);
 661                         mconsole_reply_len(entry->req, console_buf, n, 0, 1);
 662                 }
 663         }
 664 }
 665
 666 static struct console mc_console = { .name      = "mc",
 667                                      .write     = console_write,
 668                                      .flags     = CON_ENABLED,
 669                                      .index     = -1 };
 670
 671 static int mc_add_console(void)
 672 {
 673         register_console(&mc_console);
 674         return 0;
 675 }
 676
 677 late_initcall(mc_add_console);
 678
 679 static void with_console(struct mc_request *req, void (*proc)(void *),
 680                          void *arg)
 681 {
 682         struct mconsole_output entry;
 683         unsigned long flags;
 684
 685         entry.req = req;
 686         spin_lock_irqsave(&client_lock, flags);
 687         list_add(&entry.list, &clients);
 688         spin_unlock_irqrestore(&client_lock, flags);
 689
 690         (*proc)(arg);
 691
 692         mconsole_reply_len(req, "", 0, 0, 0);
 693
 694         spin_lock_irqsave(&client_lock, flags);
 695         list_del(&entry.list);
 696         spin_unlock_irqrestore(&client_lock, flags);
 697 }
 698
 699 #ifdef CONFIG_MAGIC_SYSRQ
 700
 701 #include <linux/sysrq.h>
 702
 703 static void sysrq_proc(void *arg)
 704 {
 705         char *op = arg;
 706         handle_sysrq(*op, NULL);
 707 }
 708
 709 void mconsole_sysrq(struct mc_request *req)
 710 {
 711         char *ptr = req->request.data;
 712
 713         ptr += strlen("sysrq");
 714         while (isspace(*ptr)) ptr++;
 715
 716         /*
 717          * With 'b', the system will shut down without a chance to reply,
 718          * so in this case, we reply first.
 719          */
 720         if (*ptr == 'b')
 721                 mconsole_reply(req, "", 0, 0);
 722
 723         with_console(req, sysrq_proc, ptr);
 724 }
 725 #else
 726 void mconsole_sysrq(struct mc_request *req)
 727 {
 728         mconsole_reply(req, "Sysrq not compiled in", 1, 0);
 729 }
 730 #endif
 731
 732 static void stack_proc(void *arg)
 733 {
 734         struct task_struct *from = current, *to = arg;
 735
 736         to->thread.saved_task = from;
 737         switch_to(from, to, from);
 738 }
 739
 740 /*
 741  * Mconsole stack trace
 742  *  Added by Allan Graves, Jeff Dike
 743  *  Dumps a stacks registers to the linux console.
 744  *  Usage stack <pid>.
 745  */
 746 void mconsole_stack(struct mc_request *req)
 747 {
 748         char *ptr = req->request.data;
 749         int pid_requested= -1;
 750         struct task_struct *to = NULL;
 751
 752         /*
 753          * Would be nice:
 754          * 1) Send showregs output to mconsole.
 755          * 2) Add a way to stack dump all pids.
 756          */
 757
 758         ptr += strlen("stack");
 759         while (isspace(*ptr))
 760                 ptr++;
 761
 762         /*
 763          * Should really check for multiple pids or reject bad args here
 764          */
 765         /* What do the arguments in mconsole_reply mean? */
 766         if (sscanf(ptr, "%d", &pid_requested) == 0) {
 767                 mconsole_reply(req, "Please specify a pid", 1, 0);
 768                 return;
 769         }
 770
 771         to = find_task_by_pid_ns(pid_requested, &init_pid_ns);
 772         if ((to == NULL) || (pid_requested == 0)) {
 773                 mconsole_reply(req, "Couldn't find that pid", 1, 0);
 774                 return;
 775         }
 776         with_console(req, stack_proc, to);
 777 }
 778
 779 /*
 780  * Changed by mconsole_setup, which is __setup, and called before SMP is
 781  * active.
 782  */
 783 static char *notify_socket = NULL;
 784
 785 static int __init mconsole_init(void)
 786 {
 787         /* long to avoid size mismatch warnings from gcc */
 788         long sock;
 789         int err;
 790         char file[UNIX_PATH_MAX];
 791
 792         if (umid_file_name("mconsole", file, sizeof(file)))
 793                 return -1;
 794         snprintf(mconsole_socket_name, sizeof(file), "%s", file);
 795
 796         sock = os_create_unix_socket(file, sizeof(file), 1);
 797         if (sock < 0) {
 798                 printk(KERN_ERR "Failed to initialize management console\n");
 799                 return 1;
 800         }
 801         if (os_set_fd_block(sock, 0))
 802                 goto out;
 803
 804         register_reboot_notifier(&reboot_notifier);
 805
 806         err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt,
 807                              IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
 808                              "mconsole", (void *)sock);
 809         if (err) {
 810                 printk(KERN_ERR "Failed to get IRQ for management console\n");
 811                 goto out;
 812         }
 813
 814         if (notify_socket != NULL) {
 815                 notify_socket = kstrdup(notify_socket, GFP_KERNEL);
 816                 if (notify_socket != NULL)
 817                         mconsole_notify(notify_socket, MCONSOLE_SOCKET,
 818                                         mconsole_socket_name,
 819                                         strlen(mconsole_socket_name) + 1);
 820                 else printk(KERN_ERR "mconsole_setup failed to strdup "
 821                             "string\n");
 822         }
 823
 824         printk(KERN_INFO "mconsole (version %d) initialized on %s\n",
 825                MCONSOLE_VERSION, mconsole_socket_name);
 826         return 0;
 827
 828  out:
 829         os_close_file(sock);
 830         return 1;
 831 }
 832
 833 __initcall(mconsole_init);
 834
 835 static int write_proc_mconsole(struct file *file, const char __user *buffer,
 836                                unsigned long count, void *data)
 837 {
 838         char *buf;
 839
 840         buf = kmalloc(count + 1, GFP_KERNEL);
 841         if (buf == NULL)
 842                 return -ENOMEM;
 843
 844         if (copy_from_user(buf, buffer, count)) {
 845                 count = -EFAULT;
 846                 goto out;
 847         }
 848
 849         buf[count] = '\0';
 850
 851         mconsole_notify(notify_socket, MCONSOLE_USER_NOTIFY, buf, count);
 852  out:
 853         kfree(buf);
 854         return count;
 855 }
 856
 857 static int create_proc_mconsole(void)
 858 {
 859         struct proc_dir_entry *ent;
 860
 861         if (notify_socket == NULL)
 862                 return 0;
 863
 864         ent = create_proc_entry("mconsole", S_IFREG | 0200, NULL);
 865         if (ent == NULL) {
 866                 printk(KERN_INFO "create_proc_mconsole : create_proc_entry "
 867                        "failed\n");
 868                 return 0;
 869         }
 870
 871         ent->read_proc = NULL;
 872         ent->write_proc = write_proc_mconsole;
 873         return 0;
 874 }
 875
 876 static DEFINE_SPINLOCK(notify_spinlock);
 877
 878 void lock_notify(void)
 879 {
 880         spin_lock(&notify_spinlock);
 881 }
 882
 883 void unlock_notify(void)
 884 {
 885         spin_unlock(&notify_spinlock);
 886 }
 887
 888 __initcall(create_proc_mconsole);
 889
 890 #define NOTIFY "notify:"
 891
 892 static int mconsole_setup(char *str)
 893 {
 894         if (!strncmp(str, NOTIFY, strlen(NOTIFY))) {
 895                 str += strlen(NOTIFY);
 896                 notify_socket = str;
 897         }
 898         else printk(KERN_ERR "mconsole_setup : Unknown option - '%s'\n", str);
 899         return 1;
 900 }
 901
 902 __setup("mconsole=", mconsole_setup);
 903
 904 __uml_help(mconsole_setup,
 905 "mconsole=notify:<socket>\n"
 906 "    Requests that the mconsole driver send a message to the named Unix\n"
 907 "    socket containing the name of the mconsole socket.  This also serves\n"
 908 "    to notify outside processes when UML has booted far enough to respond\n"
 909 "    to mconsole requests.\n\n"
 910 );
 911
 912 static int notify_panic(struct notifier_block *self, unsigned long unused1,
 913                         void *ptr)
 914 {
 915         char *message = ptr;
 916
 917         if (notify_socket == NULL)
 918                 return 0;
 919
 920         mconsole_notify(notify_socket, MCONSOLE_PANIC, message,
 921                         strlen(message) + 1);
 922         return 0;
 923 }
 924
 925 static struct notifier_block panic_exit_notifier = {
 926         .notifier_call          = notify_panic,
 927         .next                   = NULL,
 928         .priority               = 1
 929 };
 930
 931 static int add_notifier(void)
 932 {
 933         atomic_notifier_chain_register(&panic_notifier_list,
 934                         &panic_exit_notifier);
 935         return 0;
 936 }
 937
 938 __initcall(add_notifier);
 939
 940 char *mconsole_notify_socket(void)
 941 {
 942         return notify_socket;
 943 }
 944
 945 EXPORT_SYMBOL(mconsole_notify_socket);