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/errno.h>
  16 #include <linux/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/ctype.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/poll.h>
  23 #include <linux/device.h>
  24 #include <linux/slab.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                 kfree(monpriv->msg_array[i]);
 178         kfree(monpriv);
 179 }
 180
 181 static struct mon_private *mon_alloc_mem(void)
 182 {
 183         int i;
 184         struct mon_private *monpriv;
 185
 186         monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
 187         if (!monpriv)
 188                 return NULL;
 189         for (i = 0; i < MON_MSGLIM; i++) {
 190                 monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg),
 191                                                     GFP_KERNEL);
 192                 if (!monpriv->msg_array[i]) {
 193                         mon_free_mem(monpriv);
 194                         return NULL;
 195                 }
 196         }
 197         return monpriv;
 198 }
 199
 200 static inline void mon_next_mca(struct mon_msg *monmsg)
 201 {
 202         if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
 203                 return;
 204         monmsg->mca_offset += 12;
 205         monmsg->pos = 0;
 206 }
 207
 208 static struct mon_msg *mon_next_message(struct mon_private *monpriv)
 209 {
 210         struct mon_msg *monmsg;
 211
 212         if (!atomic_read(&monpriv->read_ready))
 213                 return NULL;
 214         monmsg = monpriv->msg_array[monpriv->read_index];
 215         if (unlikely(monmsg->replied_msglim)) {
 216                 monmsg->replied_msglim = 0;
 217                 monmsg->msglim_reached = 0;
 218                 monmsg->pos = 0;
 219                 monmsg->mca_offset = 0;
 220                 monpriv->read_index = (monpriv->read_index + 1) %
 221                                       MON_MSGLIM;
 222                 atomic_dec(&monpriv->read_ready);
 223                 return ERR_PTR(-EOVERFLOW);
 224         }
 225         return monmsg;
 226 }
 227
 228
 229 /******************************************************************************
 230  *                               IUCV handler                                 *
 231  *****************************************************************************/
 232 static void mon_iucv_path_complete(struct iucv_path *path, u8 ipuser[16])
 233 {
 234         struct mon_private *monpriv = path->private;
 235
 236         atomic_set(&monpriv->iucv_connected, 1);
 237         wake_up(&mon_conn_wait_queue);
 238 }
 239
 240 static void mon_iucv_path_severed(struct iucv_path *path, u8 ipuser[16])
 241 {
 242         struct mon_private *monpriv = path->private;
 243
 244         pr_err("z/VM *MONITOR system service disconnected with rc=%i\n",
 245                ipuser[0]);
 246         iucv_path_sever(path, NULL);
 247         atomic_set(&monpriv->iucv_severed, 1);
 248         wake_up(&mon_conn_wait_queue);
 249         wake_up_interruptible(&mon_read_wait_queue);
 250 }
 251
 252 static void mon_iucv_message_pending(struct iucv_path *path,
 253                                      struct iucv_message *msg)
 254 {
 255         struct mon_private *monpriv = path->private;
 256
 257         memcpy(&monpriv->msg_array[monpriv->write_index]->msg,
 258                msg, sizeof(*msg));
 259         if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
 260                 pr_warning("The read queue for monitor data is full\n");
 261                 monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
 262         }
 263         monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
 264         atomic_inc(&monpriv->read_ready);
 265         wake_up_interruptible(&mon_read_wait_queue);
 266 }
 267
 268 static struct iucv_handler monreader_iucv_handler = {
 269         .path_complete   = mon_iucv_path_complete,
 270         .path_severed    = mon_iucv_path_severed,
 271         .message_pending = mon_iucv_message_pending,
 272 };
 273
 274 /******************************************************************************
 275  *                               file operations                              *
 276  *****************************************************************************/
 277 static int mon_open(struct inode *inode, struct file *filp)
 278 {
 279         struct mon_private *monpriv;
 280         int rc;
 281
 282         /*
 283          * only one user allowed
 284          */
 285         rc = -EBUSY;
 286         if (test_and_set_bit(MON_IN_USE, &mon_in_use))
 287                 goto out;
 288
 289         rc = -ENOMEM;
 290         monpriv = mon_alloc_mem();
 291         if (!monpriv)
 292                 goto out_use;
 293
 294         /*
 295          * Connect to *MONITOR service
 296          */
 297         monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
 298         if (!monpriv->path)
 299                 goto out_priv;
 300         rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
 301                                MON_SERVICE, NULL, user_data_connect, monpriv);
 302         if (rc) {
 303                 pr_err("Connecting to the z/VM *MONITOR system service "
 304                        "failed with rc=%i\n", rc);
 305                 rc = -EIO;
 306                 goto out_path;
 307         }
 308         /*
 309          * Wait for connection confirmation
 310          */
 311         wait_event(mon_conn_wait_queue,
 312                    atomic_read(&monpriv->iucv_connected) ||
 313                    atomic_read(&monpriv->iucv_severed));
 314         if (atomic_read(&monpriv->iucv_severed)) {
 315                 atomic_set(&monpriv->iucv_severed, 0);
 316                 atomic_set(&monpriv->iucv_connected, 0);
 317                 rc = -EIO;
 318                 goto out_path;
 319         }
 320         filp->private_data = monpriv;
 321         dev_set_drvdata(monreader_device, monpriv);
 322         return nonseekable_open(inode, filp);
 323
 324 out_path:
 325         iucv_path_free(monpriv->path);
 326 out_priv:
 327         mon_free_mem(monpriv);
 328 out_use:
 329         clear_bit(MON_IN_USE, &mon_in_use);
 330 out:
 331         return rc;
 332 }
 333
 334 static int mon_close(struct inode *inode, struct file *filp)
 335 {
 336         int rc, i;
 337         struct mon_private *monpriv = filp->private_data;
 338
 339         /*
 340          * Close IUCV connection and unregister
 341          */
 342         if (monpriv->path) {
 343                 rc = iucv_path_sever(monpriv->path, user_data_sever);
 344                 if (rc)
 345                         pr_warning("Disconnecting the z/VM *MONITOR system "
 346                                    "service failed with rc=%i\n", rc);
 347                 iucv_path_free(monpriv->path);
 348         }
 349
 350         atomic_set(&monpriv->iucv_severed, 0);
 351         atomic_set(&monpriv->iucv_connected, 0);
 352         atomic_set(&monpriv->read_ready, 0);
 353         atomic_set(&monpriv->msglim_count, 0);
 354         monpriv->write_index  = 0;
 355         monpriv->read_index   = 0;
 356         dev_set_drvdata(monreader_device, NULL);
 357
 358         for (i = 0; i < MON_MSGLIM; i++)
 359                 kfree(monpriv->msg_array[i]);
 360         kfree(monpriv);
 361         clear_bit(MON_IN_USE, &mon_in_use);
 362         return 0;
 363 }
 364
 365 static ssize_t mon_read(struct file *filp, char __user *data,
 366                         size_t count, loff_t *ppos)
 367 {
 368         struct mon_private *monpriv = filp->private_data;
 369         struct mon_msg *monmsg;
 370         int ret;
 371         u32 mce_start;
 372
 373         monmsg = mon_next_message(monpriv);
 374         if (IS_ERR(monmsg))
 375                 return PTR_ERR(monmsg);
 376
 377         if (!monmsg) {
 378                 if (filp->f_flags & O_NONBLOCK)
 379                         return -EAGAIN;
 380                 ret = wait_event_interruptible(mon_read_wait_queue,
 381                                         atomic_read(&monpriv->read_ready) ||
 382                                         atomic_read(&monpriv->iucv_severed));
 383                 if (ret)
 384                         return ret;
 385                 if (unlikely(atomic_read(&monpriv->iucv_severed)))
 386                         return -EIO;
 387                 monmsg = monpriv->msg_array[monpriv->read_index];
 388         }
 389
 390         if (!monmsg->pos)
 391                 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
 392         if (mon_check_mca(monmsg))
 393                 goto reply;
 394
 395         /* read monitor control element (12 bytes) first */
 396         mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
 397         if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
 398                 count = min(count, (size_t) mce_start + 12 - monmsg->pos);
 399                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 400                                    count);
 401                 if (ret)
 402                         return -EFAULT;
 403                 monmsg->pos += count;
 404                 if (monmsg->pos == mce_start + 12)
 405                         monmsg->pos = mon_rec_start(monmsg);
 406                 goto out_copy;
 407         }
 408
 409         /* read records */
 410         if (monmsg->pos <= mon_rec_end(monmsg)) {
 411                 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
 412                                             + 1);
 413                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 414                                    count);
 415                 if (ret)
 416                         return -EFAULT;
 417                 monmsg->pos += count;
 418                 if (monmsg->pos > mon_rec_end(monmsg))
 419                         mon_next_mca(monmsg);
 420                 goto out_copy;
 421         }
 422 reply:
 423         ret = mon_send_reply(monmsg, monpriv);
 424         return ret;
 425
 426 out_copy:
 427         *ppos += count;
 428         return count;
 429 }
 430
 431 static unsigned int mon_poll(struct file *filp, struct poll_table_struct *p)
 432 {
 433         struct mon_private *monpriv = filp->private_data;
 434
 435         poll_wait(filp, &mon_read_wait_queue, p);
 436         if (unlikely(atomic_read(&monpriv->iucv_severed)))
 437                 return POLLERR;
 438         if (atomic_read(&monpriv->read_ready))
 439                 return POLLIN | POLLRDNORM;
 440         return 0;
 441 }
 442
 443 static const struct file_operations mon_fops = {
 444         .owner   = THIS_MODULE,
 445         .open    = &mon_open,
 446         .release = &mon_close,
 447         .read    = &mon_read,
 448         .poll    = &mon_poll,
 449         .llseek  = noop_llseek,
 450 };
 451
 452 static struct miscdevice mon_dev = {
 453         .name       = "monreader",
 454         .fops       = &mon_fops,
 455         .minor      = MISC_DYNAMIC_MINOR,
 456 };
 457
 458
 459 /******************************************************************************
 460  *                              suspend / resume                              *
 461  *****************************************************************************/
 462 static int monreader_freeze(struct device *dev)
 463 {
 464         struct mon_private *monpriv = dev_get_drvdata(dev);
 465         int rc;
 466
 467         if (!monpriv)
 468                 return 0;
 469         if (monpriv->path) {
 470                 rc = iucv_path_sever(monpriv->path, user_data_sever);
 471                 if (rc)
 472                         pr_warning("Disconnecting the z/VM *MONITOR system "
 473                                    "service failed with rc=%i\n", rc);
 474                 iucv_path_free(monpriv->path);
 475         }
 476         atomic_set(&monpriv->iucv_severed, 0);
 477         atomic_set(&monpriv->iucv_connected, 0);
 478         atomic_set(&monpriv->read_ready, 0);
 479         atomic_set(&monpriv->msglim_count, 0);
 480         monpriv->write_index  = 0;
 481         monpriv->read_index   = 0;
 482         monpriv->path = NULL;
 483         return 0;
 484 }
 485
 486 static int monreader_thaw(struct device *dev)
 487 {
 488         struct mon_private *monpriv = dev_get_drvdata(dev);
 489         int rc;
 490
 491         if (!monpriv)
 492                 return 0;
 493         rc = -ENOMEM;
 494         monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
 495         if (!monpriv->path)
 496                 goto out;
 497         rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
 498                                MON_SERVICE, NULL, user_data_connect, monpriv);
 499         if (rc) {
 500                 pr_err("Connecting to the z/VM *MONITOR system service "
 501                        "failed with rc=%i\n", rc);
 502                 goto out_path;
 503         }
 504         wait_event(mon_conn_wait_queue,
 505                    atomic_read(&monpriv->iucv_connected) ||
 506                    atomic_read(&monpriv->iucv_severed));
 507         if (atomic_read(&monpriv->iucv_severed))
 508                 goto out_path;
 509         return 0;
 510 out_path:
 511         rc = -EIO;
 512         iucv_path_free(monpriv->path);
 513         monpriv->path = NULL;
 514 out:
 515         atomic_set(&monpriv->iucv_severed, 1);
 516         return rc;
 517 }
 518
 519 static int monreader_restore(struct device *dev)
 520 {
 521         int rc;
 522
 523         segment_unload(mon_dcss_name);
 524         rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
 525                           &mon_dcss_start, &mon_dcss_end);
 526         if (rc < 0) {
 527                 segment_warning(rc, mon_dcss_name);
 528                 panic("fatal monreader resume error: no monitor dcss\n");
 529         }
 530         return monreader_thaw(dev);
 531 }
 532
 533 static const struct dev_pm_ops monreader_pm_ops = {
 534         .freeze  = monreader_freeze,
 535         .thaw    = monreader_thaw,
 536         .restore = monreader_restore,
 537 };
 538
 539 static struct device_driver monreader_driver = {
 540         .name = "monreader",
 541         .bus  = &iucv_bus,
 542         .pm   = &monreader_pm_ops,
 543 };
 544
 545
 546 /******************************************************************************
 547  *                              module init/exit                              *
 548  *****************************************************************************/
 549 static int __init mon_init(void)
 550 {
 551         int rc;
 552
 553         if (!MACHINE_IS_VM) {
 554                 pr_err("The z/VM *MONITOR record device driver cannot be "
 555                        "loaded without z/VM\n");
 556                 return -ENODEV;
 557         }
 558
 559         /*
 560          * Register with IUCV and connect to *MONITOR service
 561          */
 562         rc = iucv_register(&monreader_iucv_handler, 1);
 563         if (rc) {
 564                 pr_err("The z/VM *MONITOR record device driver failed to "
 565                        "register with IUCV\n");
 566                 return rc;
 567         }
 568
 569         rc = driver_register(&monreader_driver);
 570         if (rc)
 571                 goto out_iucv;
 572         monreader_device = kzalloc(sizeof(struct device), GFP_KERNEL);
 573         if (!monreader_device) {
 574                 rc = -ENOMEM;
 575                 goto out_driver;
 576         }
 577
 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         /*
 611          * misc_register() has to be the last action in module_init(), because
 612          * file operations will be available right after this.
 613          */
 614         rc = misc_register(&mon_dev);
 615         if (rc < 0 )
 616                 goto out;
 617         return 0;
 618
 619 out:
 620         segment_unload(mon_dcss_name);
 621 out_device:
 622         device_unregister(monreader_device);
 623 out_driver:
 624         driver_unregister(&monreader_driver);
 625 out_iucv:
 626         iucv_unregister(&monreader_iucv_handler, 1);
 627         return rc;
 628 }
 629
 630 static void __exit mon_exit(void)
 631 {
 632         segment_unload(mon_dcss_name);
 633         misc_deregister(&mon_dev);
 634         device_unregister(monreader_device);
 635         driver_unregister(&monreader_driver);
 636         iucv_unregister(&monreader_iucv_handler, 1);
 637         return;
 638 }
 639
 640
 641 module_init(mon_init);
 642 module_exit(mon_exit);
 643
 644 module_param_string(mondcss, mon_dcss_name, 9, 0444);
 645 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
 646                  "service, max. 8 chars. Default is MONDCSS");
 647
 648 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
 649 MODULE_DESCRIPTION("Character device driver for reading z/VM "
 650                    "monitor service records.");
 651 MODULE_LICENSE("GPL");