drivers/s390/char/monreader.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Character device driver for reading z/VM *MONITOR service records.
   4  *
   5  * Copyright IBM Corp. 2004, 2009
   6  *
   7  * Author: Gerald Schaefer <gerald.schaefer@de.ibm.com>
   8  */
   9
  10 #define KMSG_COMPONENT "monreader"
  11 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  12
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/init.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 <linux/slab.h>
  26 #include <net/iucv/iucv.h>
  27 #include <linux/uaccess.h>
  28 #include <asm/ebcdic.h>
  29 #include <asm/extmem.h>
  30
  31
  32 #define MON_COLLECT_SAMPLE 0x80
  33 #define MON_COLLECT_EVENT  0x40
  34 #define MON_SERVICE        "*MONITOR"
  35 #define MON_IN_USE         0x01
  36 #define MON_MSGLIM         255
  37
  38 static char mon_dcss_name[9] = "MONDCSS\0";
  39
  40 struct mon_msg {
  41         u32 pos;
  42         u32 mca_offset;
  43         struct iucv_message msg;
  44         char msglim_reached;
  45         char replied_msglim;
  46 };
  47
  48 struct mon_private {
  49         struct iucv_path *path;
  50         struct mon_msg *msg_array[MON_MSGLIM];
  51         unsigned int   write_index;
  52         unsigned int   read_index;
  53         atomic_t msglim_count;
  54         atomic_t read_ready;
  55         atomic_t iucv_connected;
  56         atomic_t iucv_severed;
  57 };
  58
  59 static unsigned long mon_in_use = 0;
  60
  61 static unsigned long mon_dcss_start;
  62 static unsigned long mon_dcss_end;
  63
  64 static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
  65 static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
  66
  67 static u8 user_data_connect[16] = {
  68         /* Version code, must be 0x01 for shared mode */
  69         0x01,
  70         /* what to collect */
  71         MON_COLLECT_SAMPLE | MON_COLLECT_EVENT,
  72         /* DCSS name in EBCDIC, 8 bytes padded with blanks */
  73         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  74         0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  75 };
  76
  77 static u8 user_data_sever[16] = {
  78         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  79         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  80 };
  81
  82 static struct device *monreader_device;
  83
  84 /******************************************************************************
  85  *                             helper functions                               *
  86  *****************************************************************************/
  87 /*
  88  * Create the 8 bytes EBCDIC DCSS segment name from
  89  * an ASCII name, incl. padding
  90  */
  91 static void dcss_mkname(char *ascii_name, char *ebcdic_name)
  92 {
  93         int i;
  94
  95         for (i = 0; i < 8; i++) {
  96                 if (ascii_name[i] == '\0')
  97                         break;
  98                 ebcdic_name[i] = toupper(ascii_name[i]);
  99         }
 100         for (; i < 8; i++)
 101                 ebcdic_name[i] = ' ';
 102         ASCEBC(ebcdic_name, 8);
 103 }
 104
 105 static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
 106 {
 107         return *(u32 *) &monmsg->msg.rmmsg;
 108 }
 109
 110 static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
 111 {
 112         return *(u32 *) &monmsg->msg.rmmsg[4];
 113 }
 114
 115 static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index)
 116 {
 117         return *((u8 *) mon_mca_start(monmsg) + monmsg->mca_offset + index);
 118 }
 119
 120 static inline u32 mon_mca_size(struct mon_msg *monmsg)
 121 {
 122         return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
 123 }
 124
 125 static inline u32 mon_rec_start(struct mon_msg *monmsg)
 126 {
 127         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4));
 128 }
 129
 130 static inline u32 mon_rec_end(struct mon_msg *monmsg)
 131 {
 132         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8));
 133 }
 134
 135 static int mon_check_mca(struct mon_msg *monmsg)
 136 {
 137         if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
 138             (mon_rec_start(monmsg) < mon_dcss_start) ||
 139             (mon_rec_end(monmsg) > mon_dcss_end) ||
 140             (mon_mca_type(monmsg, 0) == 0) ||
 141             (mon_mca_size(monmsg) % 12 != 0) ||
 142             (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
 143             (mon_mca_end(monmsg) > mon_dcss_end) ||
 144             (mon_mca_start(monmsg) < mon_dcss_start) ||
 145             ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
 146                 return -EINVAL;
 147         return 0;
 148 }
 149
 150 static int mon_send_reply(struct mon_msg *monmsg,
 151                           struct mon_private *monpriv)
 152 {
 153         int rc;
 154
 155         rc = iucv_message_reply(monpriv->path, &monmsg->msg,
 156                                 IUCV_IPRMDATA, NULL, 0);
 157         atomic_dec(&monpriv->msglim_count);
 158         if (likely(!monmsg->msglim_reached)) {
 159                 monmsg->pos = 0;
 160                 monmsg->mca_offset = 0;
 161                 monpriv->read_index = (monpriv->read_index + 1) %
 162                                       MON_MSGLIM;
 163                 atomic_dec(&monpriv->read_ready);
 164         } else
 165                 monmsg->replied_msglim = 1;
 166         if (rc) {
 167                 pr_err("Reading monitor data failed with rc=%i\n", rc);
 168                 return -EIO;
 169         }
 170         return 0;
 171 }
 172
 173 static void mon_free_mem(struct mon_private *monpriv)
 174 {
 175         int i;
 176
 177         for (i = 0; i < MON_MSGLIM; 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)
 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)
 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_warn("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         rc = -EBUSY;
 287         if (test_and_set_bit(MON_IN_USE, &mon_in_use))
 288                 goto out;
 289
 290         rc = -ENOMEM;
 291         monpriv = mon_alloc_mem();
 292         if (!monpriv)
 293                 goto out_use;
 294
 295         /*
 296          * Connect to *MONITOR service
 297          */
 298         monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
 299         if (!monpriv->path)
 300                 goto out_priv;
 301         rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
 302                                MON_SERVICE, NULL, user_data_connect, monpriv);
 303         if (rc) {
 304                 pr_err("Connecting to the z/VM *MONITOR system service "
 305                        "failed with rc=%i\n", rc);
 306                 rc = -EIO;
 307                 goto out_path;
 308         }
 309         /*
 310          * Wait for connection confirmation
 311          */
 312         wait_event(mon_conn_wait_queue,
 313                    atomic_read(&monpriv->iucv_connected) ||
 314                    atomic_read(&monpriv->iucv_severed));
 315         if (atomic_read(&monpriv->iucv_severed)) {
 316                 atomic_set(&monpriv->iucv_severed, 0);
 317                 atomic_set(&monpriv->iucv_connected, 0);
 318                 rc = -EIO;
 319                 goto out_path;
 320         }
 321         filp->private_data = monpriv;
 322         dev_set_drvdata(monreader_device, monpriv);
 323         return nonseekable_open(inode, filp);
 324
 325 out_path:
 326         iucv_path_free(monpriv->path);
 327 out_priv:
 328         mon_free_mem(monpriv);
 329 out_use:
 330         clear_bit(MON_IN_USE, &mon_in_use);
 331 out:
 332         return rc;
 333 }
 334
 335 static int mon_close(struct inode *inode, struct file *filp)
 336 {
 337         int rc, i;
 338         struct mon_private *monpriv = filp->private_data;
 339
 340         /*
 341          * Close IUCV connection and unregister
 342          */
 343         if (monpriv->path) {
 344                 rc = iucv_path_sever(monpriv->path, user_data_sever);
 345                 if (rc)
 346                         pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n",
 347                                 rc);
 348                 iucv_path_free(monpriv->path);
 349         }
 350
 351         atomic_set(&monpriv->iucv_severed, 0);
 352         atomic_set(&monpriv->iucv_connected, 0);
 353         atomic_set(&monpriv->read_ready, 0);
 354         atomic_set(&monpriv->msglim_count, 0);
 355         monpriv->write_index  = 0;
 356         monpriv->read_index   = 0;
 357         dev_set_drvdata(monreader_device, NULL);
 358
 359         for (i = 0; i < MON_MSGLIM; i++)
 360                 kfree(monpriv->msg_array[i]);
 361         kfree(monpriv);
 362         clear_bit(MON_IN_USE, &mon_in_use);
 363         return 0;
 364 }
 365
 366 static ssize_t mon_read(struct file *filp, char __user *data,
 367                         size_t count, loff_t *ppos)
 368 {
 369         struct mon_private *monpriv = filp->private_data;
 370         struct mon_msg *monmsg;
 371         int ret;
 372         u32 mce_start;
 373
 374         monmsg = mon_next_message(monpriv);
 375         if (IS_ERR(monmsg))
 376                 return PTR_ERR(monmsg);
 377
 378         if (!monmsg) {
 379                 if (filp->f_flags & O_NONBLOCK)
 380                         return -EAGAIN;
 381                 ret = wait_event_interruptible(mon_read_wait_queue,
 382                                         atomic_read(&monpriv->read_ready) ||
 383                                         atomic_read(&monpriv->iucv_severed));
 384                 if (ret)
 385                         return ret;
 386                 if (unlikely(atomic_read(&monpriv->iucv_severed)))
 387                         return -EIO;
 388                 monmsg = monpriv->msg_array[monpriv->read_index];
 389         }
 390
 391         if (!monmsg->pos)
 392                 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
 393         if (mon_check_mca(monmsg))
 394                 goto reply;
 395
 396         /* read monitor control element (12 bytes) first */
 397         mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
 398         if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
 399                 count = min(count, (size_t) mce_start + 12 - monmsg->pos);
 400                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 401                                    count);
 402                 if (ret)
 403                         return -EFAULT;
 404                 monmsg->pos += count;
 405                 if (monmsg->pos == mce_start + 12)
 406                         monmsg->pos = mon_rec_start(monmsg);
 407                 goto out_copy;
 408         }
 409
 410         /* read records */
 411         if (monmsg->pos <= mon_rec_end(monmsg)) {
 412                 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
 413                                             + 1);
 414                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 415                                    count);
 416                 if (ret)
 417                         return -EFAULT;
 418                 monmsg->pos += count;
 419                 if (monmsg->pos > mon_rec_end(monmsg))
 420                         mon_next_mca(monmsg);
 421                 goto out_copy;
 422         }
 423 reply:
 424         ret = mon_send_reply(monmsg, monpriv);
 425         return ret;
 426
 427 out_copy:
 428         *ppos += count;
 429         return count;
 430 }
 431
 432 static __poll_t mon_poll(struct file *filp, struct poll_table_struct *p)
 433 {
 434         struct mon_private *monpriv = filp->private_data;
 435
 436         poll_wait(filp, &mon_read_wait_queue, p);
 437         if (unlikely(atomic_read(&monpriv->iucv_severed)))
 438                 return EPOLLERR;
 439         if (atomic_read(&monpriv->read_ready))
 440                 return EPOLLIN | EPOLLRDNORM;
 441         return 0;
 442 }
 443
 444 static const struct file_operations mon_fops = {
 445         .owner   = THIS_MODULE,
 446         .open    = &mon_open,
 447         .release = &mon_close,
 448         .read    = &mon_read,
 449         .poll    = &mon_poll,
 450         .llseek  = noop_llseek,
 451 };
 452
 453 static struct miscdevice mon_dev = {
 454         .name       = "monreader",
 455         .fops       = &mon_fops,
 456         .minor      = MISC_DYNAMIC_MINOR,
 457 };
 458
 459
 460 /******************************************************************************
 461  *                              suspend / resume                              *
 462  *****************************************************************************/
 463 static int monreader_freeze(struct device *dev)
 464 {
 465         struct mon_private *monpriv = dev_get_drvdata(dev);
 466         int rc;
 467
 468         if (!monpriv)
 469                 return 0;
 470         if (monpriv->path) {
 471                 rc = iucv_path_sever(monpriv->path, user_data_sever);
 472                 if (rc)
 473                         pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n",
 474                                 rc);
 475                 iucv_path_free(monpriv->path);
 476         }
 477         atomic_set(&monpriv->iucv_severed, 0);
 478         atomic_set(&monpriv->iucv_connected, 0);
 479         atomic_set(&monpriv->read_ready, 0);
 480         atomic_set(&monpriv->msglim_count, 0);
 481         monpriv->write_index  = 0;
 482         monpriv->read_index   = 0;
 483         monpriv->path = NULL;
 484         return 0;
 485 }
 486
 487 static int monreader_thaw(struct device *dev)
 488 {
 489         struct mon_private *monpriv = dev_get_drvdata(dev);
 490         int rc;
 491
 492         if (!monpriv)
 493                 return 0;
 494         rc = -ENOMEM;
 495         monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
 496         if (!monpriv->path)
 497                 goto out;
 498         rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
 499                                MON_SERVICE, NULL, user_data_connect, monpriv);
 500         if (rc) {
 501                 pr_err("Connecting to the z/VM *MONITOR system service "
 502                        "failed with rc=%i\n", rc);
 503                 goto out_path;
 504         }
 505         wait_event(mon_conn_wait_queue,
 506                    atomic_read(&monpriv->iucv_connected) ||
 507                    atomic_read(&monpriv->iucv_severed));
 508         if (atomic_read(&monpriv->iucv_severed))
 509                 goto out_path;
 510         return 0;
 511 out_path:
 512         rc = -EIO;
 513         iucv_path_free(monpriv->path);
 514         monpriv->path = NULL;
 515 out:
 516         atomic_set(&monpriv->iucv_severed, 1);
 517         return rc;
 518 }
 519
 520 static int monreader_restore(struct device *dev)
 521 {
 522         int rc;
 523
 524         segment_unload(mon_dcss_name);
 525         rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
 526                           &mon_dcss_start, &mon_dcss_end);
 527         if (rc < 0) {
 528                 segment_warning(rc, mon_dcss_name);
 529                 panic("fatal monreader resume error: no monitor dcss\n");
 530         }
 531         return monreader_thaw(dev);
 532 }
 533
 534 static const struct dev_pm_ops monreader_pm_ops = {
 535         .freeze  = monreader_freeze,
 536         .thaw    = monreader_thaw,
 537         .restore = monreader_restore,
 538 };
 539
 540 static struct device_driver monreader_driver = {
 541         .name = "monreader",
 542         .bus  = &iucv_bus,
 543         .pm   = &monreader_pm_ops,
 544 };
 545
 546
 547 /******************************************************************************
 548  *                              module init/exit                              *
 549  *****************************************************************************/
 550 static int __init mon_init(void)
 551 {
 552         int rc;
 553
 554         if (!MACHINE_IS_VM) {
 555                 pr_err("The z/VM *MONITOR record device driver cannot be "
 556                        "loaded without z/VM\n");
 557                 return -ENODEV;
 558         }
 559
 560         /*
 561          * Register with IUCV and connect to *MONITOR service
 562          */
 563         rc = iucv_register(&monreader_iucv_handler, 1);
 564         if (rc) {
 565                 pr_err("The z/VM *MONITOR record device driver failed to "
 566                        "register with IUCV\n");
 567                 return rc;
 568         }
 569
 570         rc = driver_register(&monreader_driver);
 571         if (rc)
 572                 goto out_iucv;
 573         monreader_device = kzalloc(sizeof(struct device), GFP_KERNEL);
 574         if (!monreader_device) {
 575                 rc = -ENOMEM;
 576                 goto out_driver;
 577         }
 578
 579         dev_set_name(monreader_device, "monreader-dev");
 580         monreader_device->bus = &iucv_bus;
 581         monreader_device->parent = iucv_root;
 582         monreader_device->driver = &monreader_driver;
 583         monreader_device->release = (void (*)(struct device *))kfree;
 584         rc = device_register(monreader_device);
 585         if (rc) {
 586                 put_device(monreader_device);
 587                 goto out_driver;
 588         }
 589
 590         rc = segment_type(mon_dcss_name);
 591         if (rc < 0) {
 592                 segment_warning(rc, mon_dcss_name);
 593                 goto out_device;
 594         }
 595         if (rc != SEG_TYPE_SC) {
 596                 pr_err("The specified *MONITOR DCSS %s does not have the "
 597                        "required type SC\n", mon_dcss_name);
 598                 rc = -EINVAL;
 599                 goto out_device;
 600         }
 601
 602         rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
 603                           &mon_dcss_start, &mon_dcss_end);
 604         if (rc < 0) {
 605                 segment_warning(rc, mon_dcss_name);
 606                 rc = -EINVAL;
 607                 goto out_device;
 608         }
 609         dcss_mkname(mon_dcss_name, &user_data_connect[8]);
 610
 611         /*
 612          * misc_register() has to be the last action in module_init(), because
 613          * file operations will be available right after this.
 614          */
 615         rc = misc_register(&mon_dev);
 616         if (rc < 0 )
 617                 goto out;
 618         return 0;
 619
 620 out:
 621         segment_unload(mon_dcss_name);
 622 out_device:
 623         device_unregister(monreader_device);
 624 out_driver:
 625         driver_unregister(&monreader_driver);
 626 out_iucv:
 627         iucv_unregister(&monreader_iucv_handler, 1);
 628         return rc;
 629 }
 630
 631 static void __exit mon_exit(void)
 632 {
 633         segment_unload(mon_dcss_name);
 634         misc_deregister(&mon_dev);
 635         device_unregister(monreader_device);
 636         driver_unregister(&monreader_driver);
 637         iucv_unregister(&monreader_iucv_handler, 1);
 638         return;
 639 }
 640
 641
 642 module_init(mon_init);
 643 module_exit(mon_exit);
 644
 645 module_param_string(mondcss, mon_dcss_name, 9, 0444);
 646 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
 647                  "service, max. 8 chars. Default is MONDCSS");
 648
 649 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
 650 MODULE_DESCRIPTION("Character device driver for reading z/VM "
 651                    "monitor service records.");
 652 MODULE_LICENSE("GPL");