drivers/s390/char/monreader.c

   1 /*
   2  * drivers/s390/char/monreader.c
   3  *
   4  * Character device driver for reading z/VM *MONITOR service records.
   5  *
   6  *   Copyright IBM Corp. 2004, 2008
   7  *   Author: Gerald Schaefer <gerald.schaefer@de.ibm.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/init.h>
  13 #include <linux/smp_lock.h>
  14 #include <linux/errno.h>
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/ctype.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/poll.h>
  22 #include <net/iucv/iucv.h>
  23 #include <asm/uaccess.h>
  24 #include <asm/ebcdic.h>
  25 #include <asm/extmem.h>
  26
  27 //#define MON_DEBUG                     /* Debug messages on/off */
  28
  29 #define MON_NAME "monreader"
  30
  31 #define P_INFO(x...)    printk(KERN_INFO MON_NAME " info: " x)
  32 #define P_ERROR(x...)   printk(KERN_ERR MON_NAME " error: " x)
  33 #define P_WARNING(x...) printk(KERN_WARNING MON_NAME " warning: " x)
  34
  35 #ifdef MON_DEBUG
  36 #define P_DEBUG(x...)   printk(KERN_DEBUG MON_NAME " debug: " x)
  37 #else
  38 #define P_DEBUG(x...)   do {} while (0)
  39 #endif
  40
  41 #define MON_COLLECT_SAMPLE 0x80
  42 #define MON_COLLECT_EVENT  0x40
  43 #define MON_SERVICE        "*MONITOR"
  44 #define MON_IN_USE         0x01
  45 #define MON_MSGLIM         255
  46
  47 static char mon_dcss_name[9] = "MONDCSS\0";
  48
  49 struct mon_msg {
  50         u32 pos;
  51         u32 mca_offset;
  52         struct iucv_message msg;
  53         char msglim_reached;
  54         char replied_msglim;
  55 };
  56
  57 struct mon_private {
  58         struct iucv_path *path;
  59         struct mon_msg *msg_array[MON_MSGLIM];
  60         unsigned int   write_index;
  61         unsigned int   read_index;
  62         atomic_t msglim_count;
  63         atomic_t read_ready;
  64         atomic_t iucv_connected;
  65         atomic_t iucv_severed;
  66 };
  67
  68 static unsigned long mon_in_use = 0;
  69
  70 static unsigned long mon_dcss_start;
  71 static unsigned long mon_dcss_end;
  72
  73 static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
  74 static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
  75
  76 static u8 user_data_connect[16] = {
  77         /* Version code, must be 0x01 for shared mode */
  78         0x01,
  79         /* what to collect */
  80         MON_COLLECT_SAMPLE | MON_COLLECT_EVENT,
  81         /* DCSS name in EBCDIC, 8 bytes padded with blanks */
  82         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  83         0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  84 };
  85
  86 static u8 user_data_sever[16] = {
  87         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  88         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  89 };
  90
  91
  92 /******************************************************************************
  93  *                             helper functions                               *
  94  *****************************************************************************/
  95 /*
  96  * Create the 8 bytes EBCDIC DCSS segment name from
  97  * an ASCII name, incl. padding
  98  */
  99 static void dcss_mkname(char *ascii_name, char *ebcdic_name)
 100 {
 101         int i;
 102
 103         for (i = 0; i < 8; i++) {
 104                 if (ascii_name[i] == '\0')
 105                         break;
 106                 ebcdic_name[i] = toupper(ascii_name[i]);
 107         };
 108         for (; i < 8; i++)
 109                 ebcdic_name[i] = ' ';
 110         ASCEBC(ebcdic_name, 8);
 111 }
 112
 113 static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
 114 {
 115         return *(u32 *) &monmsg->msg.rmmsg;
 116 }
 117
 118 static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
 119 {
 120         return *(u32 *) &monmsg->msg.rmmsg[4];
 121 }
 122
 123 static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index)
 124 {
 125         return *((u8 *) mon_mca_start(monmsg) + monmsg->mca_offset + index);
 126 }
 127
 128 static inline u32 mon_mca_size(struct mon_msg *monmsg)
 129 {
 130         return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
 131 }
 132
 133 static inline u32 mon_rec_start(struct mon_msg *monmsg)
 134 {
 135         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4));
 136 }
 137
 138 static inline u32 mon_rec_end(struct mon_msg *monmsg)
 139 {
 140         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8));
 141 }
 142
 143 static int mon_check_mca(struct mon_msg *monmsg)
 144 {
 145         if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
 146             (mon_rec_start(monmsg) < mon_dcss_start) ||
 147             (mon_rec_end(monmsg) > mon_dcss_end) ||
 148             (mon_mca_type(monmsg, 0) == 0) ||
 149             (mon_mca_size(monmsg) % 12 != 0) ||
 150             (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
 151             (mon_mca_end(monmsg) > mon_dcss_end) ||
 152             (mon_mca_start(monmsg) < mon_dcss_start) ||
 153             ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
 154                 return -EINVAL;
 155         return 0;
 156 }
 157
 158 static int mon_send_reply(struct mon_msg *monmsg,
 159                           struct mon_private *monpriv)
 160 {
 161         int rc;
 162
 163         rc = iucv_message_reply(monpriv->path, &monmsg->msg,
 164                                 IUCV_IPRMDATA, NULL, 0);
 165         atomic_dec(&monpriv->msglim_count);
 166         if (likely(!monmsg->msglim_reached)) {
 167                 monmsg->pos = 0;
 168                 monmsg->mca_offset = 0;
 169                 monpriv->read_index = (monpriv->read_index + 1) %
 170                                       MON_MSGLIM;
 171                 atomic_dec(&monpriv->read_ready);
 172         } else
 173                 monmsg->replied_msglim = 1;
 174         if (rc) {
 175                 P_ERROR("read, IUCV reply failed with rc = %i\n\n", rc);
 176                 return -EIO;
 177         }
 178         return 0;
 179 }
 180
 181 static void mon_free_mem(struct mon_private *monpriv)
 182 {
 183         int i;
 184
 185         for (i = 0; i < MON_MSGLIM; i++)
 186                 if (monpriv->msg_array[i])
 187                         kfree(monpriv->msg_array[i]);
 188         kfree(monpriv);
 189 }
 190
 191 static struct mon_private *mon_alloc_mem(void)
 192 {
 193         int i;
 194         struct mon_private *monpriv;
 195
 196         monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
 197         if (!monpriv)
 198                 return NULL;
 199         for (i = 0; i < MON_MSGLIM; i++) {
 200                 monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg),
 201                                                     GFP_KERNEL);
 202                 if (!monpriv->msg_array[i]) {
 203                         mon_free_mem(monpriv);
 204                         return NULL;
 205                 }
 206         }
 207         return monpriv;
 208 }
 209
 210 static inline void mon_next_mca(struct mon_msg *monmsg)
 211 {
 212         if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
 213                 return;
 214         monmsg->mca_offset += 12;
 215         monmsg->pos = 0;
 216 }
 217
 218 static struct mon_msg *mon_next_message(struct mon_private *monpriv)
 219 {
 220         struct mon_msg *monmsg;
 221
 222         if (!atomic_read(&monpriv->read_ready))
 223                 return NULL;
 224         monmsg = monpriv->msg_array[monpriv->read_index];
 225         if (unlikely(monmsg->replied_msglim)) {
 226                 monmsg->replied_msglim = 0;
 227                 monmsg->msglim_reached = 0;
 228                 monmsg->pos = 0;
 229                 monmsg->mca_offset = 0;
 230                 monpriv->read_index = (monpriv->read_index + 1) %
 231                                       MON_MSGLIM;
 232                 atomic_dec(&monpriv->read_ready);
 233                 return ERR_PTR(-EOVERFLOW);
 234         }
 235         return monmsg;
 236 }
 237
 238
 239 /******************************************************************************
 240  *                               IUCV handler                                 *
 241  *****************************************************************************/
 242 static void mon_iucv_path_complete(struct iucv_path *path, u8 ipuser[16])
 243 {
 244         struct mon_private *monpriv = path->private;
 245
 246         atomic_set(&monpriv->iucv_connected, 1);
 247         wake_up(&mon_conn_wait_queue);
 248 }
 249
 250 static void mon_iucv_path_severed(struct iucv_path *path, u8 ipuser[16])
 251 {
 252         struct mon_private *monpriv = path->private;
 253
 254         P_ERROR("IUCV connection severed with rc = 0x%X\n", ipuser[0]);
 255         iucv_path_sever(path, NULL);
 256         atomic_set(&monpriv->iucv_severed, 1);
 257         wake_up(&mon_conn_wait_queue);
 258         wake_up_interruptible(&mon_read_wait_queue);
 259 }
 260
 261 static void mon_iucv_message_pending(struct iucv_path *path,
 262                                      struct iucv_message *msg)
 263 {
 264         struct mon_private *monpriv = path->private;
 265
 266         memcpy(&monpriv->msg_array[monpriv->write_index]->msg,
 267                msg, sizeof(*msg));
 268         if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
 269                 P_WARNING("IUCV message pending, message limit (%i) reached\n",
 270                           MON_MSGLIM);
 271                 monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
 272         }
 273         monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
 274         atomic_inc(&monpriv->read_ready);
 275         wake_up_interruptible(&mon_read_wait_queue);
 276 }
 277
 278 static struct iucv_handler monreader_iucv_handler = {
 279         .path_complete   = mon_iucv_path_complete,
 280         .path_severed    = mon_iucv_path_severed,
 281         .message_pending = mon_iucv_message_pending,
 282 };
 283
 284 /******************************************************************************
 285  *                               file operations                              *
 286  *****************************************************************************/
 287 static int mon_open(struct inode *inode, struct file *filp)
 288 {
 289         struct mon_private *monpriv;
 290         int rc;
 291
 292         /*
 293          * only one user allowed
 294          */
 295         lock_kernel();
 296         rc = -EBUSY;
 297         if (test_and_set_bit(MON_IN_USE, &mon_in_use))
 298                 goto out;
 299
 300         rc = -ENOMEM;
 301         monpriv = mon_alloc_mem();
 302         if (!monpriv)
 303                 goto out_use;
 304
 305         /*
 306          * Connect to *MONITOR service
 307          */
 308         monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
 309         if (!monpriv->path)
 310                 goto out_priv;
 311         rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
 312                                MON_SERVICE, NULL, user_data_connect, monpriv);
 313         if (rc) {
 314                 P_ERROR("iucv connection to *MONITOR failed with "
 315                         "IPUSER SEVER code = %i\n", rc);
 316                 rc = -EIO;
 317                 goto out_path;
 318         }
 319         /*
 320          * Wait for connection confirmation
 321          */
 322         wait_event(mon_conn_wait_queue,
 323                    atomic_read(&monpriv->iucv_connected) ||
 324                    atomic_read(&monpriv->iucv_severed));
 325         if (atomic_read(&monpriv->iucv_severed)) {
 326                 atomic_set(&monpriv->iucv_severed, 0);
 327                 atomic_set(&monpriv->iucv_connected, 0);
 328                 rc = -EIO;
 329                 goto out_path;
 330         }
 331         filp->private_data = monpriv;
 332         unlock_kernel();
 333         return nonseekable_open(inode, filp);
 334
 335 out_path:
 336         kfree(monpriv->path);
 337 out_priv:
 338         mon_free_mem(monpriv);
 339 out_use:
 340         clear_bit(MON_IN_USE, &mon_in_use);
 341 out:
 342         unlock_kernel();
 343         return rc;
 344 }
 345
 346 static int mon_close(struct inode *inode, struct file *filp)
 347 {
 348         int rc, i;
 349         struct mon_private *monpriv = filp->private_data;
 350
 351         /*
 352          * Close IUCV connection and unregister
 353          */
 354         rc = iucv_path_sever(monpriv->path, user_data_sever);
 355         if (rc)
 356                 P_ERROR("close, iucv_sever failed with rc = %i\n", rc);
 357
 358         atomic_set(&monpriv->iucv_severed, 0);
 359         atomic_set(&monpriv->iucv_connected, 0);
 360         atomic_set(&monpriv->read_ready, 0);
 361         atomic_set(&monpriv->msglim_count, 0);
 362         monpriv->write_index  = 0;
 363         monpriv->read_index   = 0;
 364
 365         for (i = 0; i < MON_MSGLIM; i++)
 366                 kfree(monpriv->msg_array[i]);
 367         kfree(monpriv);
 368         clear_bit(MON_IN_USE, &mon_in_use);
 369         return 0;
 370 }
 371
 372 static ssize_t mon_read(struct file *filp, char __user *data,
 373                         size_t count, loff_t *ppos)
 374 {
 375         struct mon_private *monpriv = filp->private_data;
 376         struct mon_msg *monmsg;
 377         int ret;
 378         u32 mce_start;
 379
 380         monmsg = mon_next_message(monpriv);
 381         if (IS_ERR(monmsg))
 382                 return PTR_ERR(monmsg);
 383
 384         if (!monmsg) {
 385                 if (filp->f_flags & O_NONBLOCK)
 386                         return -EAGAIN;
 387                 ret = wait_event_interruptible(mon_read_wait_queue,
 388                                         atomic_read(&monpriv->read_ready) ||
 389                                         atomic_read(&monpriv->iucv_severed));
 390                 if (ret)
 391                         return ret;
 392                 if (unlikely(atomic_read(&monpriv->iucv_severed)))
 393                         return -EIO;
 394                 monmsg = monpriv->msg_array[monpriv->read_index];
 395         }
 396
 397         if (!monmsg->pos)
 398                 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
 399         if (mon_check_mca(monmsg))
 400                 goto reply;
 401
 402         /* read monitor control element (12 bytes) first */
 403         mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
 404         if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
 405                 count = min(count, (size_t) mce_start + 12 - monmsg->pos);
 406                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 407                                    count);
 408                 if (ret)
 409                         return -EFAULT;
 410                 monmsg->pos += count;
 411                 if (monmsg->pos == mce_start + 12)
 412                         monmsg->pos = mon_rec_start(monmsg);
 413                 goto out_copy;
 414         }
 415
 416         /* read records */
 417         if (monmsg->pos <= mon_rec_end(monmsg)) {
 418                 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
 419                                             + 1);
 420                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 421                                    count);
 422                 if (ret)
 423                         return -EFAULT;
 424                 monmsg->pos += count;
 425                 if (monmsg->pos > mon_rec_end(monmsg))
 426                         mon_next_mca(monmsg);
 427                 goto out_copy;
 428         }
 429 reply:
 430         ret = mon_send_reply(monmsg, monpriv);
 431         return ret;
 432
 433 out_copy:
 434         *ppos += count;
 435         return count;
 436 }
 437
 438 static unsigned int mon_poll(struct file *filp, struct poll_table_struct *p)
 439 {
 440         struct mon_private *monpriv = filp->private_data;
 441
 442         poll_wait(filp, &mon_read_wait_queue, p);
 443         if (unlikely(atomic_read(&monpriv->iucv_severed)))
 444                 return POLLERR;
 445         if (atomic_read(&monpriv->read_ready))
 446                 return POLLIN | POLLRDNORM;
 447         return 0;
 448 }
 449
 450 static const struct file_operations mon_fops = {
 451         .owner   = THIS_MODULE,
 452         .open    = &mon_open,
 453         .release = &mon_close,
 454         .read    = &mon_read,
 455         .poll    = &mon_poll,
 456 };
 457
 458 static struct miscdevice mon_dev = {
 459         .name       = "monreader",
 460         .fops       = &mon_fops,
 461         .minor      = MISC_DYNAMIC_MINOR,
 462 };
 463
 464 /******************************************************************************
 465  *                              module init/exit                              *
 466  *****************************************************************************/
 467 static int __init mon_init(void)
 468 {
 469         int rc;
 470
 471         if (!MACHINE_IS_VM) {
 472                 P_ERROR("not running under z/VM, driver not loaded\n");
 473                 return -ENODEV;
 474         }
 475
 476         /*
 477          * Register with IUCV and connect to *MONITOR service
 478          */
 479         rc = iucv_register(&monreader_iucv_handler, 1);
 480         if (rc) {
 481                 P_ERROR("failed to register with iucv driver\n");
 482                 return rc;
 483         }
 484
 485         rc = segment_type(mon_dcss_name);
 486         if (rc < 0) {
 487                 segment_warning(rc, mon_dcss_name);
 488                 goto out_iucv;
 489         }
 490         if (rc != SEG_TYPE_SC) {
 491                 P_ERROR("segment %s has unsupported type, should be SC\n",
 492                         mon_dcss_name);
 493                 rc = -EINVAL;
 494                 goto out_iucv;
 495         }
 496
 497         rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
 498                           &mon_dcss_start, &mon_dcss_end);
 499         if (rc < 0) {
 500                 segment_warning(rc, mon_dcss_name);
 501                 rc = -EINVAL;
 502                 goto out_iucv;
 503         }
 504         dcss_mkname(mon_dcss_name, &user_data_connect[8]);
 505
 506         rc = misc_register(&mon_dev);
 507         if (rc < 0 )
 508                 goto out;
 509         return 0;
 510
 511 out:
 512         segment_unload(mon_dcss_name);
 513 out_iucv:
 514         iucv_unregister(&monreader_iucv_handler, 1);
 515         return rc;
 516 }
 517
 518 static void __exit mon_exit(void)
 519 {
 520         segment_unload(mon_dcss_name);
 521         WARN_ON(misc_deregister(&mon_dev) != 0);
 522         iucv_unregister(&monreader_iucv_handler, 1);
 523         return;
 524 }
 525
 526
 527 module_init(mon_init);
 528 module_exit(mon_exit);
 529
 530 module_param_string(mondcss, mon_dcss_name, 9, 0444);
 531 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
 532                  "service, max. 8 chars. Default is MONDCSS");
 533
 534 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
 535 MODULE_DESCRIPTION("Character device driver for reading z/VM "
 536                    "monitor service records.");
 537 MODULE_LICENSE("GPL");