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