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 #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/smp_lock.h>
  17 #include <linux/errno.h>
  18 #include <linux/types.h>
  19 #include <linux/kernel.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/ctype.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/poll.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
  82 /******************************************************************************
  83  *                             helper functions                               *
  84  *****************************************************************************/
  85 /*
  86  * Create the 8 bytes EBCDIC DCSS segment name from
  87  * an ASCII name, incl. padding
  88  */
  89 static void dcss_mkname(char *ascii_name, char *ebcdic_name)
  90 {
  91         int i;
  92
  93         for (i = 0; i < 8; i++) {
  94                 if (ascii_name[i] == '\0')
  95                         break;
  96                 ebcdic_name[i] = toupper(ascii_name[i]);
  97         };
  98         for (; i < 8; i++)
  99                 ebcdic_name[i] = ' ';
 100         ASCEBC(ebcdic_name, 8);
 101 }
 102
 103 static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
 104 {
 105         return *(u32 *) &monmsg->msg.rmmsg;
 106 }
 107
 108 static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
 109 {
 110         return *(u32 *) &monmsg->msg.rmmsg[4];
 111 }
 112
 113 static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index)
 114 {
 115         return *((u8 *) mon_mca_start(monmsg) + monmsg->mca_offset + index);
 116 }
 117
 118 static inline u32 mon_mca_size(struct mon_msg *monmsg)
 119 {
 120         return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
 121 }
 122
 123 static inline u32 mon_rec_start(struct mon_msg *monmsg)
 124 {
 125         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4));
 126 }
 127
 128 static inline u32 mon_rec_end(struct mon_msg *monmsg)
 129 {
 130         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8));
 131 }
 132
 133 static int mon_check_mca(struct mon_msg *monmsg)
 134 {
 135         if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
 136             (mon_rec_start(monmsg) < mon_dcss_start) ||
 137             (mon_rec_end(monmsg) > mon_dcss_end) ||
 138             (mon_mca_type(monmsg, 0) == 0) ||
 139             (mon_mca_size(monmsg) % 12 != 0) ||
 140             (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
 141             (mon_mca_end(monmsg) > mon_dcss_end) ||
 142             (mon_mca_start(monmsg) < mon_dcss_start) ||
 143             ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
 144                 return -EINVAL;
 145         return 0;
 146 }
 147
 148 static int mon_send_reply(struct mon_msg *monmsg,
 149                           struct mon_private *monpriv)
 150 {
 151         int rc;
 152
 153         rc = iucv_message_reply(monpriv->path, &monmsg->msg,
 154                                 IUCV_IPRMDATA, NULL, 0);
 155         atomic_dec(&monpriv->msglim_count);
 156         if (likely(!monmsg->msglim_reached)) {
 157                 monmsg->pos = 0;
 158                 monmsg->mca_offset = 0;
 159                 monpriv->read_index = (monpriv->read_index + 1) %
 160                                       MON_MSGLIM;
 161                 atomic_dec(&monpriv->read_ready);
 162         } else
 163                 monmsg->replied_msglim = 1;
 164         if (rc) {
 165                 pr_err("Reading monitor data failed with rc=%i\n", rc);
 166                 return -EIO;
 167         }
 168         return 0;
 169 }
 170
 171 static void mon_free_mem(struct mon_private *monpriv)
 172 {
 173         int i;
 174
 175         for (i = 0; i < MON_MSGLIM; i++)
 176                 if (monpriv->msg_array[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         lock_kernel();
 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         unlock_kernel();
 323         return nonseekable_open(inode, filp);
 324
 325 out_path:
 326         kfree(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         unlock_kernel();
 333         return rc;
 334 }
 335
 336 static int mon_close(struct inode *inode, struct file *filp)
 337 {
 338         int rc, i;
 339         struct mon_private *monpriv = filp->private_data;
 340
 341         /*
 342          * Close IUCV connection and unregister
 343          */
 344         rc = iucv_path_sever(monpriv->path, user_data_sever);
 345         if (rc)
 346                 pr_warning("Disconnecting the z/VM *MONITOR system service "
 347                            "failed with rc=%i\n", rc);
 348
 349         atomic_set(&monpriv->iucv_severed, 0);
 350         atomic_set(&monpriv->iucv_connected, 0);
 351         atomic_set(&monpriv->read_ready, 0);
 352         atomic_set(&monpriv->msglim_count, 0);
 353         monpriv->write_index  = 0;
 354         monpriv->read_index   = 0;
 355
 356         for (i = 0; i < MON_MSGLIM; i++)
 357                 kfree(monpriv->msg_array[i]);
 358         kfree(monpriv);
 359         clear_bit(MON_IN_USE, &mon_in_use);
 360         return 0;
 361 }
 362
 363 static ssize_t mon_read(struct file *filp, char __user *data,
 364                         size_t count, loff_t *ppos)
 365 {
 366         struct mon_private *monpriv = filp->private_data;
 367         struct mon_msg *monmsg;
 368         int ret;
 369         u32 mce_start;
 370
 371         monmsg = mon_next_message(monpriv);
 372         if (IS_ERR(monmsg))
 373                 return PTR_ERR(monmsg);
 374
 375         if (!monmsg) {
 376                 if (filp->f_flags & O_NONBLOCK)
 377                         return -EAGAIN;
 378                 ret = wait_event_interruptible(mon_read_wait_queue,
 379                                         atomic_read(&monpriv->read_ready) ||
 380                                         atomic_read(&monpriv->iucv_severed));
 381                 if (ret)
 382                         return ret;
 383                 if (unlikely(atomic_read(&monpriv->iucv_severed)))
 384                         return -EIO;
 385                 monmsg = monpriv->msg_array[monpriv->read_index];
 386         }
 387
 388         if (!monmsg->pos)
 389                 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
 390         if (mon_check_mca(monmsg))
 391                 goto reply;
 392
 393         /* read monitor control element (12 bytes) first */
 394         mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
 395         if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
 396                 count = min(count, (size_t) mce_start + 12 - monmsg->pos);
 397                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 398                                    count);
 399                 if (ret)
 400                         return -EFAULT;
 401                 monmsg->pos += count;
 402                 if (monmsg->pos == mce_start + 12)
 403                         monmsg->pos = mon_rec_start(monmsg);
 404                 goto out_copy;
 405         }
 406
 407         /* read records */
 408         if (monmsg->pos <= mon_rec_end(monmsg)) {
 409                 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
 410                                             + 1);
 411                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 412                                    count);
 413                 if (ret)
 414                         return -EFAULT;
 415                 monmsg->pos += count;
 416                 if (monmsg->pos > mon_rec_end(monmsg))
 417                         mon_next_mca(monmsg);
 418                 goto out_copy;
 419         }
 420 reply:
 421         ret = mon_send_reply(monmsg, monpriv);
 422         return ret;
 423
 424 out_copy:
 425         *ppos += count;
 426         return count;
 427 }
 428
 429 static unsigned int mon_poll(struct file *filp, struct poll_table_struct *p)
 430 {
 431         struct mon_private *monpriv = filp->private_data;
 432
 433         poll_wait(filp, &mon_read_wait_queue, p);
 434         if (unlikely(atomic_read(&monpriv->iucv_severed)))
 435                 return POLLERR;
 436         if (atomic_read(&monpriv->read_ready))
 437                 return POLLIN | POLLRDNORM;
 438         return 0;
 439 }
 440
 441 static const struct file_operations mon_fops = {
 442         .owner   = THIS_MODULE,
 443         .open    = &mon_open,
 444         .release = &mon_close,
 445         .read    = &mon_read,
 446         .poll    = &mon_poll,
 447 };
 448
 449 static struct miscdevice mon_dev = {
 450         .name       = "monreader",
 451         .fops       = &mon_fops,
 452         .minor      = MISC_DYNAMIC_MINOR,
 453 };
 454
 455 /******************************************************************************
 456  *                              module init/exit                              *
 457  *****************************************************************************/
 458 static int __init mon_init(void)
 459 {
 460         int rc;
 461
 462         if (!MACHINE_IS_VM) {
 463                 pr_err("The z/VM *MONITOR record device driver cannot be "
 464                        "loaded without z/VM\n");
 465                 return -ENODEV;
 466         }
 467
 468         /*
 469          * Register with IUCV and connect to *MONITOR service
 470          */
 471         rc = iucv_register(&monreader_iucv_handler, 1);
 472         if (rc) {
 473                 pr_err("The z/VM *MONITOR record device driver failed to "
 474                        "register with IUCV\n");
 475                 return rc;
 476         }
 477
 478         rc = segment_type(mon_dcss_name);
 479         if (rc < 0) {
 480                 segment_warning(rc, mon_dcss_name);
 481                 goto out_iucv;
 482         }
 483         if (rc != SEG_TYPE_SC) {
 484                 pr_err("The specified *MONITOR DCSS %s does not have the "
 485                        "required type SC\n", mon_dcss_name);
 486                 rc = -EINVAL;
 487                 goto out_iucv;
 488         }
 489
 490         rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
 491                           &mon_dcss_start, &mon_dcss_end);
 492         if (rc < 0) {
 493                 segment_warning(rc, mon_dcss_name);
 494                 rc = -EINVAL;
 495                 goto out_iucv;
 496         }
 497         dcss_mkname(mon_dcss_name, &user_data_connect[8]);
 498
 499         rc = misc_register(&mon_dev);
 500         if (rc < 0 )
 501                 goto out;
 502         return 0;
 503
 504 out:
 505         segment_unload(mon_dcss_name);
 506 out_iucv:
 507         iucv_unregister(&monreader_iucv_handler, 1);
 508         return rc;
 509 }
 510
 511 static void __exit mon_exit(void)
 512 {
 513         segment_unload(mon_dcss_name);
 514         WARN_ON(misc_deregister(&mon_dev) != 0);
 515         iucv_unregister(&monreader_iucv_handler, 1);
 516         return;
 517 }
 518
 519
 520 module_init(mon_init);
 521 module_exit(mon_exit);
 522
 523 module_param_string(mondcss, mon_dcss_name, 9, 0444);
 524 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
 525                  "service, max. 8 chars. Default is MONDCSS");
 526
 527 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
 528 MODULE_DESCRIPTION("Character device driver for reading z/VM "
 529                    "monitor service records.");
 530 MODULE_LICENSE("GPL");