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