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/slab.h>
  25 #include <net/iucv/iucv.h>
  26 #include <linux/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  *                             helper functions                               *
  83  *****************************************************************************/
  84 /*
  85  * Create the 8 bytes EBCDIC DCSS segment name from
  86  * an ASCII name, incl. padding
  87  */
  88 static void dcss_mkname(char *ascii_name, char *ebcdic_name)
  89 {
  90         int i;
  91
  92         for (i = 0; i < 8; i++) {
  93                 if (ascii_name[i] == '\0')
  94                         break;
  95                 ebcdic_name[i] = toupper(ascii_name[i]);
  96         }
  97         for (; i < 8; i++)
  98                 ebcdic_name[i] = ' ';
  99         ASCEBC(ebcdic_name, 8);
 100 }
 101
 102 static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
 103 {
 104         return *(u32 *) &monmsg->msg.rmmsg;
 105 }
 106
 107 static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
 108 {
 109         return *(u32 *) &monmsg->msg.rmmsg[4];
 110 }
 111
 112 static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index)
 113 {
 114         return *((u8 *) mon_mca_start(monmsg) + monmsg->mca_offset + index);
 115 }
 116
 117 static inline u32 mon_mca_size(struct mon_msg *monmsg)
 118 {
 119         return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
 120 }
 121
 122 static inline u32 mon_rec_start(struct mon_msg *monmsg)
 123 {
 124         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4));
 125 }
 126
 127 static inline u32 mon_rec_end(struct mon_msg *monmsg)
 128 {
 129         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8));
 130 }
 131
 132 static int mon_check_mca(struct mon_msg *monmsg)
 133 {
 134         if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
 135             (mon_rec_start(monmsg) < mon_dcss_start) ||
 136             (mon_rec_end(monmsg) > mon_dcss_end) ||
 137             (mon_mca_type(monmsg, 0) == 0) ||
 138             (mon_mca_size(monmsg) % 12 != 0) ||
 139             (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
 140             (mon_mca_end(monmsg) > mon_dcss_end) ||
 141             (mon_mca_start(monmsg) < mon_dcss_start) ||
 142             ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
 143                 return -EINVAL;
 144         return 0;
 145 }
 146
 147 static int mon_send_reply(struct mon_msg *monmsg,
 148                           struct mon_private *monpriv)
 149 {
 150         int rc;
 151
 152         rc = iucv_message_reply(monpriv->path, &monmsg->msg,
 153                                 IUCV_IPRMDATA, NULL, 0);
 154         atomic_dec(&monpriv->msglim_count);
 155         if (likely(!monmsg->msglim_reached)) {
 156                 monmsg->pos = 0;
 157                 monmsg->mca_offset = 0;
 158                 monpriv->read_index = (monpriv->read_index + 1) %
 159                                       MON_MSGLIM;
 160                 atomic_dec(&monpriv->read_ready);
 161         } else
 162                 monmsg->replied_msglim = 1;
 163         if (rc) {
 164                 pr_err("Reading monitor data failed with rc=%i\n", rc);
 165                 return -EIO;
 166         }
 167         return 0;
 168 }
 169
 170 static void mon_free_mem(struct mon_private *monpriv)
 171 {
 172         int i;
 173
 174         for (i = 0; i < MON_MSGLIM; i++)
 175                 kfree(monpriv->msg_array[i]);
 176         kfree(monpriv);
 177 }
 178
 179 static struct mon_private *mon_alloc_mem(void)
 180 {
 181         int i;
 182         struct mon_private *monpriv;
 183
 184         monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
 185         if (!monpriv)
 186                 return NULL;
 187         for (i = 0; i < MON_MSGLIM; i++) {
 188                 monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg),
 189                                                     GFP_KERNEL);
 190                 if (!monpriv->msg_array[i]) {
 191                         mon_free_mem(monpriv);
 192                         return NULL;
 193                 }
 194         }
 195         return monpriv;
 196 }
 197
 198 static inline void mon_next_mca(struct mon_msg *monmsg)
 199 {
 200         if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
 201                 return;
 202         monmsg->mca_offset += 12;
 203         monmsg->pos = 0;
 204 }
 205
 206 static struct mon_msg *mon_next_message(struct mon_private *monpriv)
 207 {
 208         struct mon_msg *monmsg;
 209
 210         if (!atomic_read(&monpriv->read_ready))
 211                 return NULL;
 212         monmsg = monpriv->msg_array[monpriv->read_index];
 213         if (unlikely(monmsg->replied_msglim)) {
 214                 monmsg->replied_msglim = 0;
 215                 monmsg->msglim_reached = 0;
 216                 monmsg->pos = 0;
 217                 monmsg->mca_offset = 0;
 218                 monpriv->read_index = (monpriv->read_index + 1) %
 219                                       MON_MSGLIM;
 220                 atomic_dec(&monpriv->read_ready);
 221                 return ERR_PTR(-EOVERFLOW);
 222         }
 223         return monmsg;
 224 }
 225
 226
 227 /******************************************************************************
 228  *                               IUCV handler                                 *
 229  *****************************************************************************/
 230 static void mon_iucv_path_complete(struct iucv_path *path, u8 *ipuser)
 231 {
 232         struct mon_private *monpriv = path->private;
 233
 234         atomic_set(&monpriv->iucv_connected, 1);
 235         wake_up(&mon_conn_wait_queue);
 236 }
 237
 238 static void mon_iucv_path_severed(struct iucv_path *path, u8 *ipuser)
 239 {
 240         struct mon_private *monpriv = path->private;
 241
 242         pr_err("z/VM *MONITOR system service disconnected with rc=%i\n",
 243                ipuser[0]);
 244         iucv_path_sever(path, NULL);
 245         atomic_set(&monpriv->iucv_severed, 1);
 246         wake_up(&mon_conn_wait_queue);
 247         wake_up_interruptible(&mon_read_wait_queue);
 248 }
 249
 250 static void mon_iucv_message_pending(struct iucv_path *path,
 251                                      struct iucv_message *msg)
 252 {
 253         struct mon_private *monpriv = path->private;
 254
 255         memcpy(&monpriv->msg_array[monpriv->write_index]->msg,
 256                msg, sizeof(*msg));
 257         if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
 258                 pr_warn("The read queue for monitor data is full\n");
 259                 monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
 260         }
 261         monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
 262         atomic_inc(&monpriv->read_ready);
 263         wake_up_interruptible(&mon_read_wait_queue);
 264 }
 265
 266 static struct iucv_handler monreader_iucv_handler = {
 267         .path_complete   = mon_iucv_path_complete,
 268         .path_severed    = mon_iucv_path_severed,
 269         .message_pending = mon_iucv_message_pending,
 270 };
 271
 272 /******************************************************************************
 273  *                               file operations                              *
 274  *****************************************************************************/
 275 static int mon_open(struct inode *inode, struct file *filp)
 276 {
 277         struct mon_private *monpriv;
 278         int rc;
 279
 280         /*
 281          * only one user allowed
 282          */
 283         rc = -EBUSY;
 284         if (test_and_set_bit(MON_IN_USE, &mon_in_use))
 285                 goto out;
 286
 287         rc = -ENOMEM;
 288         monpriv = mon_alloc_mem();
 289         if (!monpriv)
 290                 goto out_use;
 291
 292         /*
 293          * Connect to *MONITOR service
 294          */
 295         monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
 296         if (!monpriv->path)
 297                 goto out_priv;
 298         rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
 299                                MON_SERVICE, NULL, user_data_connect, monpriv);
 300         if (rc) {
 301                 pr_err("Connecting to the z/VM *MONITOR system service "
 302                        "failed with rc=%i\n", rc);
 303                 rc = -EIO;
 304                 goto out_path;
 305         }
 306         /*
 307          * Wait for connection confirmation
 308          */
 309         wait_event(mon_conn_wait_queue,
 310                    atomic_read(&monpriv->iucv_connected) ||
 311                    atomic_read(&monpriv->iucv_severed));
 312         if (atomic_read(&monpriv->iucv_severed)) {
 313                 atomic_set(&monpriv->iucv_severed, 0);
 314                 atomic_set(&monpriv->iucv_connected, 0);
 315                 rc = -EIO;
 316                 goto out_path;
 317         }
 318         filp->private_data = monpriv;
 319         return nonseekable_open(inode, filp);
 320
 321 out_path:
 322         iucv_path_free(monpriv->path);
 323 out_priv:
 324         mon_free_mem(monpriv);
 325 out_use:
 326         clear_bit(MON_IN_USE, &mon_in_use);
 327 out:
 328         return rc;
 329 }
 330
 331 static int mon_close(struct inode *inode, struct file *filp)
 332 {
 333         int rc, i;
 334         struct mon_private *monpriv = filp->private_data;
 335
 336         /*
 337          * Close IUCV connection and unregister
 338          */
 339         if (monpriv->path) {
 340                 rc = iucv_path_sever(monpriv->path, user_data_sever);
 341                 if (rc)
 342                         pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n",
 343                                 rc);
 344                 iucv_path_free(monpriv->path);
 345         }
 346
 347         atomic_set(&monpriv->iucv_severed, 0);
 348         atomic_set(&monpriv->iucv_connected, 0);
 349         atomic_set(&monpriv->read_ready, 0);
 350         atomic_set(&monpriv->msglim_count, 0);
 351         monpriv->write_index  = 0;
 352         monpriv->read_index   = 0;
 353
 354         for (i = 0; i < MON_MSGLIM; i++)
 355                 kfree(monpriv->msg_array[i]);
 356         kfree(monpriv);
 357         clear_bit(MON_IN_USE, &mon_in_use);
 358         return 0;
 359 }
 360
 361 static ssize_t mon_read(struct file *filp, char __user *data,
 362                         size_t count, loff_t *ppos)
 363 {
 364         struct mon_private *monpriv = filp->private_data;
 365         struct mon_msg *monmsg;
 366         int ret;
 367         u32 mce_start;
 368
 369         monmsg = mon_next_message(monpriv);
 370         if (IS_ERR(monmsg))
 371                 return PTR_ERR(monmsg);
 372
 373         if (!monmsg) {
 374                 if (filp->f_flags & O_NONBLOCK)
 375                         return -EAGAIN;
 376                 ret = wait_event_interruptible(mon_read_wait_queue,
 377                                         atomic_read(&monpriv->read_ready) ||
 378                                         atomic_read(&monpriv->iucv_severed));
 379                 if (ret)
 380                         return ret;
 381                 if (unlikely(atomic_read(&monpriv->iucv_severed)))
 382                         return -EIO;
 383                 monmsg = monpriv->msg_array[monpriv->read_index];
 384         }
 385
 386         if (!monmsg->pos)
 387                 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
 388         if (mon_check_mca(monmsg))
 389                 goto reply;
 390
 391         /* read monitor control element (12 bytes) first */
 392         mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
 393         if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
 394                 count = min(count, (size_t) mce_start + 12 - monmsg->pos);
 395                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 396                                    count);
 397                 if (ret)
 398                         return -EFAULT;
 399                 monmsg->pos += count;
 400                 if (monmsg->pos == mce_start + 12)
 401                         monmsg->pos = mon_rec_start(monmsg);
 402                 goto out_copy;
 403         }
 404
 405         /* read records */
 406         if (monmsg->pos <= mon_rec_end(monmsg)) {
 407                 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
 408                                             + 1);
 409                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 410                                    count);
 411                 if (ret)
 412                         return -EFAULT;
 413                 monmsg->pos += count;
 414                 if (monmsg->pos > mon_rec_end(monmsg))
 415                         mon_next_mca(monmsg);
 416                 goto out_copy;
 417         }
 418 reply:
 419         ret = mon_send_reply(monmsg, monpriv);
 420         return ret;
 421
 422 out_copy:
 423         *ppos += count;
 424         return count;
 425 }
 426
 427 static __poll_t mon_poll(struct file *filp, struct poll_table_struct *p)
 428 {
 429         struct mon_private *monpriv = filp->private_data;
 430
 431         poll_wait(filp, &mon_read_wait_queue, p);
 432         if (unlikely(atomic_read(&monpriv->iucv_severed)))
 433                 return EPOLLERR;
 434         if (atomic_read(&monpriv->read_ready))
 435                 return EPOLLIN | EPOLLRDNORM;
 436         return 0;
 437 }
 438
 439 static const struct file_operations mon_fops = {
 440         .owner   = THIS_MODULE,
 441         .open    = &mon_open,
 442         .release = &mon_close,
 443         .read    = &mon_read,
 444         .poll    = &mon_poll,
 445         .llseek  = noop_llseek,
 446 };
 447
 448 static struct miscdevice mon_dev = {
 449         .name       = "monreader",
 450         .fops       = &mon_fops,
 451         .minor      = MISC_DYNAMIC_MINOR,
 452 };
 453
 454 /******************************************************************************
 455  *                              module init/exit                              *
 456  *****************************************************************************/
 457 static int __init mon_init(void)
 458 {
 459         int rc;
 460
 461         if (!MACHINE_IS_VM) {
 462                 pr_err("The z/VM *MONITOR record device driver cannot be "
 463                        "loaded without z/VM\n");
 464                 return -ENODEV;
 465         }
 466
 467         /*
 468          * Register with IUCV and connect to *MONITOR service
 469          */
 470         rc = iucv_register(&monreader_iucv_handler, 1);
 471         if (rc) {
 472                 pr_err("The z/VM *MONITOR record device driver failed to "
 473                        "register with IUCV\n");
 474                 return rc;
 475         }
 476
 477         rc = segment_type(mon_dcss_name);
 478         if (rc < 0) {
 479                 segment_warning(rc, mon_dcss_name);
 480                 goto out_iucv;
 481         }
 482         if (rc != SEG_TYPE_SC) {
 483                 pr_err("The specified *MONITOR DCSS %s does not have the "
 484                        "required type SC\n", mon_dcss_name);
 485                 rc = -EINVAL;
 486                 goto out_iucv;
 487         }
 488
 489         rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
 490                           &mon_dcss_start, &mon_dcss_end);
 491         if (rc < 0) {
 492                 segment_warning(rc, mon_dcss_name);
 493                 rc = -EINVAL;
 494                 goto out_iucv;
 495         }
 496         dcss_mkname(mon_dcss_name, &user_data_connect[8]);
 497
 498         /*
 499          * misc_register() has to be the last action in module_init(), because
 500          * file operations will be available right after this.
 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         misc_deregister(&mon_dev);
 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");