linux/drivers/s390/char/monreader.c
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   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
  37static char mon_dcss_name[9] = "MONDCSS\0";
  38
  39struct mon_msg {
  40        u32 pos;
  41        u32 mca_offset;
  42        struct iucv_message msg;
  43        char msglim_reached;
  44        char replied_msglim;
  45};
  46
  47struct 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
  58static unsigned long mon_in_use = 0;
  59
  60static unsigned long mon_dcss_start;
  61static unsigned long mon_dcss_end;
  62
  63static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
  64static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
  65
  66static 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
  76static 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 */
  89static 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
 103static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
 104{
 105        return *(u32 *) &monmsg->msg.rmmsg;
 106}
 107
 108static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
 109{
 110        return *(u32 *) &monmsg->msg.rmmsg[4];
 111}
 112
 113static 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
 118static inline u32 mon_mca_size(struct mon_msg *monmsg)
 119{
 120        return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
 121}
 122
 123static inline u32 mon_rec_start(struct mon_msg *monmsg)
 124{
 125        return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4));
 126}
 127
 128static inline u32 mon_rec_end(struct mon_msg *monmsg)
 129{
 130        return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8));
 131}
 132
 133static 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
 148static 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
 171static 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
 181static 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
 200static 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
 208static 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 *****************************************************************************/
 232static 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
 240static 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
 252static 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
 268static 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 *****************************************************************************/
 277static 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
 325out_path:
 326        kfree(monpriv->path);
 327out_priv:
 328        mon_free_mem(monpriv);
 329out_use:
 330        clear_bit(MON_IN_USE, &mon_in_use);
 331out:
 332        unlock_kernel();
 333        return rc;
 334}
 335
 336static 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
 363static 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        }
 420reply:
 421        ret = mon_send_reply(monmsg, monpriv);
 422        return ret;
 423
 424out_copy:
 425        *ppos += count;
 426        return count;
 427}
 428
 429static 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
 441static 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
 449static struct miscdevice mon_dev = {
 450        .name       = "monreader",
 451        .fops       = &mon_fops,
 452        .minor      = MISC_DYNAMIC_MINOR,
 453};
 454
 455/******************************************************************************
 456 *                              module init/exit                              *
 457 *****************************************************************************/
 458static 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
 504out:
 505        segment_unload(mon_dcss_name);
 506out_iucv:
 507        iucv_unregister(&monreader_iucv_handler, 1);
 508        return rc;
 509}
 510
 511static 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
 520module_init(mon_init);
 521module_exit(mon_exit);
 522
 523module_param_string(mondcss, mon_dcss_name, 9, 0444);
 524MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
 525                 "service, max. 8 chars. Default is MONDCSS");
 526
 527MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
 528MODULE_DESCRIPTION("Character device driver for reading z/VM "
 529                   "monitor service records.");
 530MODULE_LICENSE("GPL");
 531