drivers/s390/char/monreader.c

   1 /*
   2  * Character device driver for reading z/VM *MONITOR service records.
   3  *
   4  * Copyright IBM Corp. 2004, 2009
   5  *
   6  * Author: Gerald Schaefer <gerald.schaefer@de.ibm.com>
   7  */
   8
   9 #define KMSG_COMPONENT "monreader"
  10 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  11
  12 #include <linux/module.h>
  13 #include <linux/moduleparam.h>
  14 #include <linux/init.h>
  15 #include <linux/smp_lock.h>
  16 #include <linux/errno.h>
  17 #include <linux/types.h>
  18 #include <linux/kernel.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/ctype.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/poll.h>
  24 #include <linux/device.h>
  25 #include <net/iucv/iucv.h>
  26 #include <asm/uaccess.h>
  27 #include <asm/ebcdic.h>
  28 #include <asm/extmem.h>
  29
  30
  31 #define MON_COLLECT_SAMPLE 0x80
  32 #define MON_COLLECT_EVENT  0x40
  33 #define MON_SERVICE        "*MONITOR"
  34 #define MON_IN_USE         0x01
  35 #define MON_MSGLIM         255
  36
  37 static char mon_dcss_name[9] = "MONDCSS\0";
  38
  39 struct mon_msg {
  40         u32 pos;
  41         u32 mca_offset;
  42         struct iucv_message msg;
  43         char msglim_reached;
  44         char replied_msglim;
  45 };
  46
  47 struct mon_private {
  48         struct iucv_path *path;
  49         struct mon_msg *msg_array[MON_MSGLIM];
  50         unsigned int   write_index;
  51         unsigned int   read_index;
  52         atomic_t msglim_count;
  53         atomic_t read_ready;
  54         atomic_t iucv_connected;
  55         atomic_t iucv_severed;
  56 };
  57
  58 static unsigned long mon_in_use = 0;
  59
  60 static unsigned long mon_dcss_start;
  61 static unsigned long mon_dcss_end;
  62
  63 static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
  64 static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
  65
  66 static u8 user_data_connect[16] = {
  67         /* Version code, must be 0x01 for shared mode */
  68         0x01,
  69         /* what to collect */
  70         MON_COLLECT_SAMPLE | MON_COLLECT_EVENT,
  71         /* DCSS name in EBCDIC, 8 bytes padded with blanks */
  72         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  73         0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  74 };
  75
  76 static u8 user_data_sever[16] = {
  77         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  78         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  79 };
  80
  81 static struct device *monreader_device;
  82
  83 /******************************************************************************
  84  *                             helper functions                               *
  85  *****************************************************************************/
  86 /*
  87  * Create the 8 bytes EBCDIC DCSS segment name from
  88  * an ASCII name, incl. padding
  89  */
  90 static void dcss_mkname(char *ascii_name, char *ebcdic_name)
  91 {
  92         int i;
  93
  94         for (i = 0; i < 8; i++) {
  95                 if (ascii_name[i] == '\0')
  96                         break;
  97                 ebcdic_name[i] = toupper(ascii_name[i]);
  98         };
  99         for (; i < 8; i++)
 100                 ebcdic_name[i] = ' ';
 101         ASCEBC(ebcdic_name, 8);
 102 }
 103
 104 static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
 105 {
 106         return *(u32 *) &monmsg->msg.rmmsg;
 107 }
 108
 109 static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
 110 {
 111         return *(u32 *) &monmsg->msg.rmmsg[4];
 112 }
 113
 114 static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index)
 115 {
 116         return *((u8 *) mon_mca_start(monmsg) + monmsg->mca_offset + index);
 117 }
 118
 119 static inline u32 mon_mca_size(struct mon_msg *monmsg)
 120 {
 121         return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
 122 }
 123
 124 static inline u32 mon_rec_start(struct mon_msg *monmsg)
 125 {
 126         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4));
 127 }
 128
 129 static inline u32 mon_rec_end(struct mon_msg *monmsg)
 130 {
 131         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8));
 132 }
 133
 134 static int mon_check_mca(struct mon_msg *monmsg)
 135 {
 136         if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
 137             (mon_rec_start(monmsg) < mon_dcss_start) ||
 138             (mon_rec_end(monmsg) > mon_dcss_end) ||
 139             (mon_mca_type(monmsg, 0) == 0) ||
 140             (mon_mca_size(monmsg) % 12 != 0) ||
 141             (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
 142             (mon_mca_end(monmsg) > mon_dcss_end) ||
 143             (mon_mca_start(monmsg) < mon_dcss_start) ||
 144             ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
 145                 return -EINVAL;
 146         return 0;
 147 }
 148
 149 static int mon_send_reply(struct mon_msg *monmsg,
 150                           struct mon_private *monpriv)
 151 {
 152         int rc;
 153
 154         rc = iucv_message_reply(monpriv->path, &monmsg->msg,
 155                                 IUCV_IPRMDATA, NULL, 0);
 156         atomic_dec(&monpriv->msglim_count);
 157         if (likely(!monmsg->msglim_reached)) {
 158                 monmsg->pos = 0;
 159                 monmsg->mca_offset = 0;
 160                 monpriv->read_index = (monpriv->read_index + 1) %
 161                                       MON_MSGLIM;
 162                 atomic_dec(&monpriv->read_ready);
 163         } else
 164                 monmsg->replied_msglim = 1;
 165         if (rc) {
 166                 pr_err("Reading monitor data failed with rc=%i\n", rc);
 167                 return -EIO;
 168         }
 169         return 0;
 170 }
 171
 172 static void mon_free_mem(struct mon_private *monpriv)
 173 {
 174         int i;
 175
 176         for (i = 0; i < MON_MSGLIM; i++)
 177                 if (monpriv->msg_array[i])
 178                         kfree(monpriv->msg_array[i]);
 179         kfree(monpriv);
 180 }
 181
 182 static struct mon_private *mon_alloc_mem(void)
 183 {
 184         int i;
 185         struct mon_private *monpriv;
 186
 187         monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
 188         if (!monpriv)
 189                 return NULL;
 190         for (i = 0; i < MON_MSGLIM; i++) {
 191                 monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg),
 192                                                     GFP_KERNEL);
 193                 if (!monpriv->msg_array[i]) {
 194                         mon_free_mem(monpriv);
 195                         return NULL;
 196                 }
 197         }
 198         return monpriv;
 199 }
 200
 201 static inline void mon_next_mca(struct mon_msg *monmsg)
 202 {
 203         if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
 204                 return;
 205         monmsg->mca_offset += 12;
 206         monmsg->pos = 0;
 207 }
 208
 209 static struct mon_msg *mon_next_message(struct mon_private *monpriv)
 210 {
 211         struct mon_msg *monmsg;
 212
 213         if (!atomic_read(&monpriv->read_ready))
 214                 return NULL;
 215         monmsg = monpriv->msg_array[monpriv->read_index];
 216         if (unlikely(monmsg->replied_msglim)) {
 217                 monmsg->replied_msglim = 0;
 218                 monmsg->msglim_reached = 0;
 219                 monmsg->pos = 0;
 220                 monmsg->mca_offset = 0;
 221                 monpriv->read_index = (monpriv->read_index + 1) %
 222                                       MON_MSGLIM;
 223                 atomic_dec(&monpriv->read_ready);
 224                 return ERR_PTR(-EOVERFLOW);
 225         }
 226         return monmsg;
 227 }
 228
 229
 230 /******************************************************************************
 231  *                               IUCV handler                                 *
 232  *****************************************************************************/
 233 static void mon_iucv_path_complete(struct iucv_path *path, u8 ipuser[16])
 234 {
 235         struct mon_private *monpriv = path->private;
 236
 237         atomic_set(&monpriv->iucv_connected, 1);
 238         wake_up(&mon_conn_wait_queue);
 239 }
 240
 241 static void mon_iucv_path_severed(struct iucv_path *path, u8 ipuser[16])
 242 {
 243         struct mon_private *monpriv = path->private;
 244
 245         pr_err("z/VM *MONITOR system service disconnected with rc=%i\n",
 246                ipuser[0]);
 247         iucv_path_sever(path, NULL);
 248         atomic_set(&monpriv->iucv_severed, 1);
 249         wake_up(&mon_conn_wait_queue);
 250         wake_up_interruptible(&mon_read_wait_queue);
 251 }
 252
 253 static void mon_iucv_message_pending(struct iucv_path *path,
 254                                      struct iucv_message *msg)
 255 {
 256         struct mon_private *monpriv = path->private;
 257
 258         memcpy(&monpriv->msg_array[monpriv->write_index]->msg,
 259                msg, sizeof(*msg));
 260         if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
 261                 pr_warning("The read queue for monitor data is full\n");
 262                 monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
 263         }
 264         monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
 265         atomic_inc(&monpriv->read_ready);
 266         wake_up_interruptible(&mon_read_wait_queue);
 267 }
 268
 269 static struct iucv_handler monreader_iucv_handler = {
 270         .path_complete   = mon_iucv_path_complete,
 271         .path_severed    = mon_iucv_path_severed,
 272         .message_pending = mon_iucv_message_pending,
 273 };
 274
 275 /******************************************************************************
 276  *                               file operations                              *
 277  *****************************************************************************/
 278 static int mon_open(struct inode *inode, struct file *filp)
 279 {
 280         struct mon_private *monpriv;
 281         int rc;
 282
 283         /*
 284          * only one user allowed
 285          */
 286         lock_kernel();
 287         rc = -EBUSY;
 288         if (test_and_set_bit(MON_IN_USE, &mon_in_use))
 289                 goto out;
 290
 291         rc = -ENOMEM;
 292         monpriv = mon_alloc_mem();
 293         if (!monpriv)
 294                 goto out_use;
 295
 296         /*
 297          * Connect to *MONITOR service
 298          */
 299         monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
 300         if (!monpriv->path)
 301                 goto out_priv;
 302         rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
 303                                MON_SERVICE, NULL, user_data_connect, monpriv);
 304         if (rc) {
 305                 pr_err("Connecting to the z/VM *MONITOR system service "
 306                        "failed with rc=%i\n", rc);
 307                 rc = -EIO;
 308                 goto out_path;
 309         }
 310         /*
 311          * Wait for connection confirmation
 312          */
 313         wait_event(mon_conn_wait_queue,
 314                    atomic_read(&monpriv->iucv_connected) ||
 315                    atomic_read(&monpriv->iucv_severed));
 316         if (atomic_read(&monpriv->iucv_severed)) {
 317                 atomic_set(&monpriv->iucv_severed, 0);
 318                 atomic_set(&monpriv->iucv_connected, 0);
 319                 rc = -EIO;
 320                 goto out_path;
 321         }
 322         filp->private_data = monpriv;
 323         dev_set_drvdata(monreader_device, monpriv);
 324         unlock_kernel();
 325         return nonseekable_open(inode, filp);
 326
 327 out_path:
 328         iucv_path_free(monpriv->path);
 329 out_priv:
 330         mon_free_mem(monpriv);
 331 out_use:
 332         clear_bit(MON_IN_USE, &mon_in_use);
 333 out:
 334         unlock_kernel();
 335         return rc;
 336 }
 337
 338 static int mon_close(struct inode *inode, struct file *filp)
 339 {
 340         int rc, i;
 341         struct mon_private *monpriv = filp->private_data;
 342
 343         /*
 344          * Close IUCV connection and unregister
 345          */
 346         if (monpriv->path) {
 347                 rc = iucv_path_sever(monpriv->path, user_data_sever);
 348                 if (rc)
 349                         pr_warning("Disconnecting the z/VM *MONITOR system "
 350                                    "service failed with rc=%i\n", rc);
 351                 iucv_path_free(monpriv->path);
 352         }
 353
 354         atomic_set(&monpriv->iucv_severed, 0);
 355         atomic_set(&monpriv->iucv_connected, 0);
 356         atomic_set(&monpriv->read_ready, 0);
 357         atomic_set(&monpriv->msglim_count, 0);
 358         monpriv->write_index  = 0;
 359         monpriv->read_index   = 0;
 360         dev_set_drvdata(monreader_device, NULL);
 361
 362         for (i = 0; i < MON_MSGLIM; i++)
 363                 kfree(monpriv->msg_array[i]);
 364         kfree(monpriv);
 365         clear_bit(MON_IN_USE, &mon_in_use);
 366         return 0;
 367 }
 368
 369 static ssize_t mon_read(struct file *filp, char __user *data,
 370                         size_t count, loff_t *ppos)
 371 {
 372         struct mon_private *monpriv = filp->private_data;
 373         struct mon_msg *monmsg;
 374         int ret;
 375         u32 mce_start;
 376
 377         monmsg = mon_next_message(monpriv);
 378         if (IS_ERR(monmsg))
 379                 return PTR_ERR(monmsg);
 380
 381         if (!monmsg) {
 382                 if (filp->f_flags & O_NONBLOCK)
 383                         return -EAGAIN;
 384                 ret = wait_event_interruptible(mon_read_wait_queue,
 385                                         atomic_read(&monpriv->read_ready) ||
 386                                         atomic_read(&monpriv->iucv_severed));
 387                 if (ret)
 388                         return ret;
 389                 if (unlikely(atomic_read(&monpriv->iucv_severed)))
 390                         return -EIO;
 391                 monmsg = monpriv->msg_array[monpriv->read_index];
 392         }
 393
 394         if (!monmsg->pos)
 395                 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
 396         if (mon_check_mca(monmsg))
 397                 goto reply;
 398
 399         /* read monitor control element (12 bytes) first */
 400         mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
 401         if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
 402                 count = min(count, (size_t) mce_start + 12 - monmsg->pos);
 403                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 404                                    count);
 405                 if (ret)
 406                         return -EFAULT;
 407                 monmsg->pos += count;
 408                 if (monmsg->pos == mce_start + 12)
 409                         monmsg->pos = mon_rec_start(monmsg);
 410                 goto out_copy;
 411         }
 412
 413         /* read records */
 414         if (monmsg->pos <= mon_rec_end(monmsg)) {
 415                 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
 416                                             + 1);
 417                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 418                                    count);
 419                 if (ret)
 420                         return -EFAULT;
 421                 monmsg->pos += count;
 422                 if (monmsg->pos > mon_rec_end(monmsg))
 423                         mon_next_mca(monmsg);
 424                 goto out_copy;
 425         }
 426 reply:
 427         ret = mon_send_reply(monmsg, monpriv);
 428         return ret;
 429
 430 out_copy:
 431         *ppos += count;
 432         return count;
 433 }
 434
 435 static unsigned int mon_poll(struct file *filp, struct poll_table_struct *p)
 436 {
 437         struct mon_private *monpriv = filp->private_data;
 438
 439         poll_wait(filp, &mon_read_wait_queue, p);
 440         if (unlikely(atomic_read(&monpriv->iucv_severed)))
 441                 return POLLERR;
 442         if (atomic_read(&monpriv->read_ready))
 443                 return POLLIN | POLLRDNORM;
 444         return 0;
 445 }
 446
 447 static const struct file_operations mon_fops = {
 448         .owner   = THIS_MODULE,
 449         .open    = &mon_open,
 450         .release = &mon_close,
 451         .read    = &mon_read,
 452         .poll    = &mon_poll,
 453 };
 454
 455 static struct miscdevice mon_dev = {
 456         .name       = "monreader",
 457         .fops       = &mon_fops,
 458         .minor      = MISC_DYNAMIC_MINOR,
 459 };
 460
 461
 462 /******************************************************************************
 463  *                              suspend / resume                              *
 464  *****************************************************************************/
 465 static int monreader_freeze(struct device *dev)
 466 {
 467         struct mon_private *monpriv = dev_get_drvdata(dev);
 468         int rc;
 469
 470         if (!monpriv)
 471                 return 0;
 472         if (monpriv->path) {
 473                 rc = iucv_path_sever(monpriv->path, user_data_sever);
 474                 if (rc)
 475                         pr_warning("Disconnecting the z/VM *MONITOR system "
 476                                    "service failed with rc=%i\n", rc);
 477                 iucv_path_free(monpriv->path);
 478         }
 479         atomic_set(&monpriv->iucv_severed, 0);
 480         atomic_set(&monpriv->iucv_connected, 0);
 481         atomic_set(&monpriv->read_ready, 0);
 482         atomic_set(&monpriv->msglim_count, 0);
 483         monpriv->write_index  = 0;
 484         monpriv->read_index   = 0;
 485         monpriv->path = NULL;
 486         return 0;
 487 }
 488
 489 static int monreader_thaw(struct device *dev)
 490 {
 491         struct mon_private *monpriv = dev_get_drvdata(dev);
 492         int rc;
 493
 494         if (!monpriv)
 495                 return 0;
 496         rc = -ENOMEM;
 497         monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
 498         if (!monpriv->path)
 499                 goto out;
 500         rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
 501                                MON_SERVICE, NULL, user_data_connect, monpriv);
 502         if (rc) {
 503                 pr_err("Connecting to the z/VM *MONITOR system service "
 504                        "failed with rc=%i\n", rc);
 505                 goto out_path;
 506         }
 507         wait_event(mon_conn_wait_queue,
 508                    atomic_read(&monpriv->iucv_connected) ||
 509                    atomic_read(&monpriv->iucv_severed));
 510         if (atomic_read(&monpriv->iucv_severed))
 511                 goto out_path;
 512         return 0;
 513 out_path:
 514         rc = -EIO;
 515         iucv_path_free(monpriv->path);
 516         monpriv->path = NULL;
 517 out:
 518         atomic_set(&monpriv->iucv_severed, 1);
 519         return rc;
 520 }
 521
 522 static int monreader_restore(struct device *dev)
 523 {
 524         int rc;
 525
 526         segment_unload(mon_dcss_name);
 527         rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
 528                           &mon_dcss_start, &mon_dcss_end);
 529         if (rc < 0) {
 530                 segment_warning(rc, mon_dcss_name);
 531                 panic("fatal monreader resume error: no monitor dcss\n");
 532         }
 533         return monreader_thaw(dev);
 534 }
 535
 536 static struct dev_pm_ops monreader_pm_ops = {
 537         .freeze  = monreader_freeze,
 538         .thaw    = monreader_thaw,
 539         .restore = monreader_restore,
 540 };
 541
 542 static struct device_driver monreader_driver = {
 543         .name = "monreader",
 544         .bus  = &iucv_bus,
 545         .pm   = &monreader_pm_ops,
 546 };
 547
 548
 549 /******************************************************************************
 550  *                              module init/exit                              *
 551  *****************************************************************************/
 552 static int __init mon_init(void)
 553 {
 554         int rc;
 555
 556         if (!MACHINE_IS_VM) {
 557                 pr_err("The z/VM *MONITOR record device driver cannot be "
 558                        "loaded without z/VM\n");
 559                 return -ENODEV;
 560         }
 561
 562         /*
 563          * Register with IUCV and connect to *MONITOR service
 564          */
 565         rc = iucv_register(&monreader_iucv_handler, 1);
 566         if (rc) {
 567                 pr_err("The z/VM *MONITOR record device driver failed to "
 568                        "register with IUCV\n");
 569                 return rc;
 570         }
 571
 572         rc = driver_register(&monreader_driver);
 573         if (rc)
 574                 goto out_iucv;
 575         monreader_device = kzalloc(sizeof(struct device), GFP_KERNEL);
 576         if (!monreader_device)
 577                 goto out_driver;
 578         dev_set_name(monreader_device, "monreader-dev");
 579         monreader_device->bus = &iucv_bus;
 580         monreader_device->parent = iucv_root;
 581         monreader_device->driver = &monreader_driver;
 582         monreader_device->release = (void (*)(struct device *))kfree;
 583         rc = device_register(monreader_device);
 584         if (rc) {
 585                 put_device(monreader_device);
 586                 goto out_driver;
 587         }
 588
 589         rc = segment_type(mon_dcss_name);
 590         if (rc < 0) {
 591                 segment_warning(rc, mon_dcss_name);
 592                 goto out_device;
 593         }
 594         if (rc != SEG_TYPE_SC) {
 595                 pr_err("The specified *MONITOR DCSS %s does not have the "
 596                        "required type SC\n", mon_dcss_name);
 597                 rc = -EINVAL;
 598                 goto out_device;
 599         }
 600
 601         rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
 602                           &mon_dcss_start, &mon_dcss_end);
 603         if (rc < 0) {
 604                 segment_warning(rc, mon_dcss_name);
 605                 rc = -EINVAL;
 606                 goto out_device;
 607         }
 608         dcss_mkname(mon_dcss_name, &user_data_connect[8]);
 609
 610         rc = misc_register(&mon_dev);
 611         if (rc < 0 )
 612                 goto out;
 613         return 0;
 614
 615 out:
 616         segment_unload(mon_dcss_name);
 617 out_device:
 618         device_unregister(monreader_device);
 619 out_driver:
 620         driver_unregister(&monreader_driver);
 621 out_iucv:
 622         iucv_unregister(&monreader_iucv_handler, 1);
 623         return rc;
 624 }
 625
 626 static void __exit mon_exit(void)
 627 {
 628         segment_unload(mon_dcss_name);
 629         WARN_ON(misc_deregister(&mon_dev) != 0);
 630         device_unregister(monreader_device);
 631         driver_unregister(&monreader_driver);
 632         iucv_unregister(&monreader_iucv_handler, 1);
 633         return;
 634 }
 635
 636
 637 module_init(mon_init);
 638 module_exit(mon_exit);
 639
 640 module_param_string(mondcss, mon_dcss_name, 9, 0444);
 641 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
 642                  "service, max. 8 chars. Default is MONDCSS");
 643
 644 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
 645 MODULE_DESCRIPTION("Character device driver for reading z/VM "
 646                    "monitor service records.");
 647 MODULE_LICENSE("GPL");