linux/drivers/s390/s390mach.c
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   1/*
   2 *  drivers/s390/s390mach.c
   3 *   S/390 machine check handler
   4 *
   5 *    Copyright IBM Corp. 2000,2008
   6 *    Author(s): Ingo Adlung (adlung@de.ibm.com)
   7 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
   8 *               Cornelia Huck <cornelia.huck@de.ibm.com>
   9 */
  10
  11#include <linux/init.h>
  12#include <linux/sched.h>
  13#include <linux/errno.h>
  14#include <linux/workqueue.h>
  15#include <linux/time.h>
  16#include <linux/device.h>
  17#include <linux/kthread.h>
  18#include <asm/etr.h>
  19#include <asm/lowcore.h>
  20#include <asm/cio.h>
  21#include "s390mach.h"
  22
  23static struct semaphore m_sem;
  24
  25static NORET_TYPE void
  26s390_handle_damage(char *msg)
  27{
  28#ifdef CONFIG_SMP
  29        smp_send_stop();
  30#endif
  31        disabled_wait((unsigned long) __builtin_return_address(0));
  32        for(;;);
  33}
  34
  35static crw_handler_t crw_handlers[NR_RSCS];
  36
  37/**
  38 * s390_register_crw_handler() - register a channel report word handler
  39 * @rsc: reporting source code to handle
  40 * @handler: handler to be registered
  41 *
  42 * Returns %0 on success and a negative error value otherwise.
  43 */
  44int s390_register_crw_handler(int rsc, crw_handler_t handler)
  45{
  46        if ((rsc < 0) || (rsc >= NR_RSCS))
  47                return -EINVAL;
  48        if (!cmpxchg(&crw_handlers[rsc], NULL, handler))
  49                return 0;
  50        return -EBUSY;
  51}
  52
  53/**
  54 * s390_unregister_crw_handler() - unregister a channel report word handler
  55 * @rsc: reporting source code to handle
  56 */
  57void s390_unregister_crw_handler(int rsc)
  58{
  59        if ((rsc < 0) || (rsc >= NR_RSCS))
  60                return;
  61        xchg(&crw_handlers[rsc], NULL);
  62        synchronize_sched();
  63}
  64
  65/*
  66 * Retrieve CRWs and call function to handle event.
  67 */
  68static int s390_collect_crw_info(void *param)
  69{
  70        struct crw crw[2];
  71        int ccode;
  72        struct semaphore *sem;
  73        unsigned int chain;
  74        int ignore;
  75
  76        sem = (struct semaphore *)param;
  77repeat:
  78        ignore = down_interruptible(sem);
  79        chain = 0;
  80        while (1) {
  81                if (unlikely(chain > 1)) {
  82                        struct crw tmp_crw;
  83
  84                        printk(KERN_WARNING"%s: Code does not support more "
  85                               "than two chained crws; please report to "
  86                               "linux390@de.ibm.com!\n", __func__);
  87                        ccode = stcrw(&tmp_crw);
  88                        printk(KERN_WARNING"%s: crw reports slct=%d, oflw=%d, "
  89                               "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
  90                               __func__, tmp_crw.slct, tmp_crw.oflw,
  91                               tmp_crw.chn, tmp_crw.rsc, tmp_crw.anc,
  92                               tmp_crw.erc, tmp_crw.rsid);
  93                        printk(KERN_WARNING"%s: This was crw number %x in the "
  94                               "chain\n", __func__, chain);
  95                        if (ccode != 0)
  96                                break;
  97                        chain = tmp_crw.chn ? chain + 1 : 0;
  98                        continue;
  99                }
 100                ccode = stcrw(&crw[chain]);
 101                if (ccode != 0)
 102                        break;
 103                printk(KERN_DEBUG "crw_info : CRW reports slct=%d, oflw=%d, "
 104                       "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
 105                       crw[chain].slct, crw[chain].oflw, crw[chain].chn,
 106                       crw[chain].rsc, crw[chain].anc, crw[chain].erc,
 107                       crw[chain].rsid);
 108                /* Check for overflows. */
 109                if (crw[chain].oflw) {
 110                        int i;
 111
 112                        pr_debug("%s: crw overflow detected!\n", __func__);
 113                        for (i = 0; i < NR_RSCS; i++) {
 114                                if (crw_handlers[i])
 115                                        crw_handlers[i](NULL, NULL, 1);
 116                        }
 117                        chain = 0;
 118                        continue;
 119                }
 120                if (crw[0].chn && !chain) {
 121                        chain++;
 122                        continue;
 123                }
 124                if (crw_handlers[crw[chain].rsc])
 125                        crw_handlers[crw[chain].rsc](&crw[0],
 126                                                     chain ? &crw[1] : NULL,
 127                                                     0);
 128                /* chain is always 0 or 1 here. */
 129                chain = crw[chain].chn ? chain + 1 : 0;
 130        }
 131        goto repeat;
 132        return 0;
 133}
 134
 135struct mcck_struct {
 136        int kill_task;
 137        int channel_report;
 138        int warning;
 139        unsigned long long mcck_code;
 140};
 141
 142static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
 143
 144/*
 145 * Main machine check handler function. Will be called with interrupts enabled
 146 * or disabled and machine checks enabled or disabled.
 147 */
 148void
 149s390_handle_mcck(void)
 150{
 151        unsigned long flags;
 152        struct mcck_struct mcck;
 153
 154        /*
 155         * Disable machine checks and get the current state of accumulated
 156         * machine checks. Afterwards delete the old state and enable machine
 157         * checks again.
 158         */
 159        local_irq_save(flags);
 160        local_mcck_disable();
 161        mcck = __get_cpu_var(cpu_mcck);
 162        memset(&__get_cpu_var(cpu_mcck), 0, sizeof(struct mcck_struct));
 163        clear_thread_flag(TIF_MCCK_PENDING);
 164        local_mcck_enable();
 165        local_irq_restore(flags);
 166
 167        if (mcck.channel_report)
 168                up(&m_sem);
 169
 170#ifdef CONFIG_MACHCHK_WARNING
 171/*
 172 * The warning may remain for a prolonged period on the bare iron.
 173 * (actually till the machine is powered off, or until the problem is gone)
 174 * So we just stop listening for the WARNING MCH and prevent continuously
 175 * being interrupted.  One caveat is however, that we must do this per
 176 * processor and cannot use the smp version of ctl_clear_bit().
 177 * On VM we only get one interrupt per virtally presented machinecheck.
 178 * Though one suffices, we may get one interrupt per (virtual) processor.
 179 */
 180        if (mcck.warning) {     /* WARNING pending ? */
 181                static int mchchk_wng_posted = 0;
 182                /*
 183                 * Use single machine clear, as we cannot handle smp right now
 184                 */
 185                __ctl_clear_bit(14, 24);        /* Disable WARNING MCH */
 186                if (xchg(&mchchk_wng_posted, 1) == 0)
 187                        kill_cad_pid(SIGPWR, 1);
 188        }
 189#endif
 190
 191        if (mcck.kill_task) {
 192                local_irq_enable();
 193                printk(KERN_EMERG "mcck: Terminating task because of machine "
 194                       "malfunction (code 0x%016llx).\n", mcck.mcck_code);
 195                printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
 196                       current->comm, current->pid);
 197                do_exit(SIGSEGV);
 198        }
 199}
 200EXPORT_SYMBOL_GPL(s390_handle_mcck);
 201
 202/*
 203 * returns 0 if all registers could be validated
 204 * returns 1 otherwise
 205 */
 206static int
 207s390_revalidate_registers(struct mci *mci)
 208{
 209        int kill_task;
 210        u64 tmpclock;
 211        u64 zero;
 212        void *fpt_save_area, *fpt_creg_save_area;
 213
 214        kill_task = 0;
 215        zero = 0;
 216        /* General purpose registers */
 217        if (!mci->gr)
 218                /*
 219                 * General purpose registers couldn't be restored and have
 220                 * unknown contents. Process needs to be terminated.
 221                 */
 222                kill_task = 1;
 223
 224        /* Revalidate floating point registers */
 225        if (!mci->fp)
 226                /*
 227                 * Floating point registers can't be restored and
 228                 * therefore the process needs to be terminated.
 229                 */
 230                kill_task = 1;
 231
 232#ifndef CONFIG_64BIT
 233        asm volatile(
 234                "       ld      0,0(%0)\n"
 235                "       ld      2,8(%0)\n"
 236                "       ld      4,16(%0)\n"
 237                "       ld      6,24(%0)"
 238                : : "a" (&S390_lowcore.floating_pt_save_area));
 239#endif
 240
 241        if (MACHINE_HAS_IEEE) {
 242#ifdef CONFIG_64BIT
 243                fpt_save_area = &S390_lowcore.floating_pt_save_area;
 244                fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
 245#else
 246                fpt_save_area = (void *) S390_lowcore.extended_save_area_addr;
 247                fpt_creg_save_area = fpt_save_area+128;
 248#endif
 249                /* Floating point control register */
 250                if (!mci->fc) {
 251                        /*
 252                         * Floating point control register can't be restored.
 253                         * Task will be terminated.
 254                         */
 255                        asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
 256                        kill_task = 1;
 257
 258                } else
 259                        asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
 260
 261                asm volatile(
 262                        "       ld      0,0(%0)\n"
 263                        "       ld      1,8(%0)\n"
 264                        "       ld      2,16(%0)\n"
 265                        "       ld      3,24(%0)\n"
 266                        "       ld      4,32(%0)\n"
 267                        "       ld      5,40(%0)\n"
 268                        "       ld      6,48(%0)\n"
 269                        "       ld      7,56(%0)\n"
 270                        "       ld      8,64(%0)\n"
 271                        "       ld      9,72(%0)\n"
 272                        "       ld      10,80(%0)\n"
 273                        "       ld      11,88(%0)\n"
 274                        "       ld      12,96(%0)\n"
 275                        "       ld      13,104(%0)\n"
 276                        "       ld      14,112(%0)\n"
 277                        "       ld      15,120(%0)\n"
 278                        : : "a" (fpt_save_area));
 279        }
 280
 281        /* Revalidate access registers */
 282        asm volatile(
 283                "       lam     0,15,0(%0)"
 284                : : "a" (&S390_lowcore.access_regs_save_area));
 285        if (!mci->ar)
 286                /*
 287                 * Access registers have unknown contents.
 288                 * Terminating task.
 289                 */
 290                kill_task = 1;
 291
 292        /* Revalidate control registers */
 293        if (!mci->cr)
 294                /*
 295                 * Control registers have unknown contents.
 296                 * Can't recover and therefore stopping machine.
 297                 */
 298                s390_handle_damage("invalid control registers.");
 299        else
 300#ifdef CONFIG_64BIT
 301                asm volatile(
 302                        "       lctlg   0,15,0(%0)"
 303                        : : "a" (&S390_lowcore.cregs_save_area));
 304#else
 305                asm volatile(
 306                        "       lctl    0,15,0(%0)"
 307                        : : "a" (&S390_lowcore.cregs_save_area));
 308#endif
 309
 310        /*
 311         * We don't even try to revalidate the TOD register, since we simply
 312         * can't write something sensible into that register.
 313         */
 314
 315#ifdef CONFIG_64BIT
 316        /*
 317         * See if we can revalidate the TOD programmable register with its
 318         * old contents (should be zero) otherwise set it to zero.
 319         */
 320        if (!mci->pr)
 321                asm volatile(
 322                        "       sr      0,0\n"
 323                        "       sckpf"
 324                        : : : "0", "cc");
 325        else
 326                asm volatile(
 327                        "       l       0,0(%0)\n"
 328                        "       sckpf"
 329                        : : "a" (&S390_lowcore.tod_progreg_save_area)
 330                        : "0", "cc");
 331#endif
 332
 333        /* Revalidate clock comparator register */
 334        asm volatile(
 335                "       stck    0(%1)\n"
 336                "       sckc    0(%1)"
 337                : "=m" (tmpclock) : "a" (&(tmpclock)) : "cc", "memory");
 338
 339        /* Check if old PSW is valid */
 340        if (!mci->wp)
 341                /*
 342                 * Can't tell if we come from user or kernel mode
 343                 * -> stopping machine.
 344                 */
 345                s390_handle_damage("old psw invalid.");
 346
 347        if (!mci->ms || !mci->pm || !mci->ia)
 348                kill_task = 1;
 349
 350        return kill_task;
 351}
 352
 353#define MAX_IPD_COUNT   29
 354#define MAX_IPD_TIME    (5 * 60 * USEC_PER_SEC) /* 5 minutes */
 355
 356/*
 357 * machine check handler.
 358 */
 359void
 360s390_do_machine_check(struct pt_regs *regs)
 361{
 362        static DEFINE_SPINLOCK(ipd_lock);
 363        static unsigned long long last_ipd;
 364        static int ipd_count;
 365        unsigned long long tmp;
 366        struct mci *mci;
 367        struct mcck_struct *mcck;
 368        int umode;
 369
 370        lockdep_off();
 371
 372        mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
 373        mcck = &__get_cpu_var(cpu_mcck);
 374        umode = user_mode(regs);
 375
 376        if (mci->sd)
 377                /* System damage -> stopping machine */
 378                s390_handle_damage("received system damage machine check.");
 379
 380        if (mci->pd) {
 381                if (mci->b) {
 382                        /* Processing backup -> verify if we can survive this */
 383                        u64 z_mcic, o_mcic, t_mcic;
 384#ifdef CONFIG_64BIT
 385                        z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
 386                        o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
 387                                  1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
 388                                  1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
 389                                  1ULL<<16);
 390#else
 391                        z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<57 | 1ULL<<50 |
 392                                  1ULL<<29);
 393                        o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
 394                                  1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
 395                                  1ULL<<30 | 1ULL<<20 | 1ULL<<17 | 1ULL<<16);
 396#endif
 397                        t_mcic = *(u64 *)mci;
 398
 399                        if (((t_mcic & z_mcic) != 0) ||
 400                            ((t_mcic & o_mcic) != o_mcic)) {
 401                                s390_handle_damage("processing backup machine "
 402                                                   "check with damage.");
 403                        }
 404
 405                        /*
 406                         * Nullifying exigent condition, therefore we might
 407                         * retry this instruction.
 408                         */
 409
 410                        spin_lock(&ipd_lock);
 411
 412                        tmp = get_clock();
 413
 414                        if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
 415                                ipd_count++;
 416                        else
 417                                ipd_count = 1;
 418
 419                        last_ipd = tmp;
 420
 421                        if (ipd_count == MAX_IPD_COUNT)
 422                                s390_handle_damage("too many ipd retries.");
 423
 424                        spin_unlock(&ipd_lock);
 425                }
 426                else {
 427                        /* Processing damage -> stopping machine */
 428                        s390_handle_damage("received instruction processing "
 429                                           "damage machine check.");
 430                }
 431        }
 432        if (s390_revalidate_registers(mci)) {
 433                if (umode) {
 434                        /*
 435                         * Couldn't restore all register contents while in
 436                         * user mode -> mark task for termination.
 437                         */
 438                        mcck->kill_task = 1;
 439                        mcck->mcck_code = *(unsigned long long *) mci;
 440                        set_thread_flag(TIF_MCCK_PENDING);
 441                }
 442                else
 443                        /*
 444                         * Couldn't restore all register contents while in
 445                         * kernel mode -> stopping machine.
 446                         */
 447                        s390_handle_damage("unable to revalidate registers.");
 448        }
 449
 450        if (mci->cd) {
 451                /* Timing facility damage */
 452                s390_handle_damage("TOD clock damaged");
 453        }
 454
 455        if (mci->ed && mci->ec) {
 456                /* External damage */
 457                if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
 458                        etr_sync_check();
 459                if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
 460                        etr_switch_to_local();
 461                if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
 462                        stp_sync_check();
 463                if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
 464                        stp_island_check();
 465        }
 466
 467        if (mci->se)
 468                /* Storage error uncorrected */
 469                s390_handle_damage("received storage error uncorrected "
 470                                   "machine check.");
 471
 472        if (mci->ke)
 473                /* Storage key-error uncorrected */
 474                s390_handle_damage("received storage key-error uncorrected "
 475                                   "machine check.");
 476
 477        if (mci->ds && mci->fa)
 478                /* Storage degradation */
 479                s390_handle_damage("received storage degradation machine "
 480                                   "check.");
 481
 482        if (mci->cp) {
 483                /* Channel report word pending */
 484                mcck->channel_report = 1;
 485                set_thread_flag(TIF_MCCK_PENDING);
 486        }
 487
 488        if (mci->w) {
 489                /* Warning pending */
 490                mcck->warning = 1;
 491                set_thread_flag(TIF_MCCK_PENDING);
 492        }
 493        lockdep_on();
 494}
 495
 496/*
 497 * s390_init_machine_check
 498 *
 499 * initialize machine check handling
 500 */
 501static int
 502machine_check_init(void)
 503{
 504        init_MUTEX_LOCKED(&m_sem);
 505        ctl_set_bit(14, 25);    /* enable external damage MCH */
 506        ctl_set_bit(14, 27);    /* enable system recovery MCH */
 507#ifdef CONFIG_MACHCHK_WARNING
 508        ctl_set_bit(14, 24);    /* enable warning MCH */
 509#endif
 510        return 0;
 511}
 512
 513/*
 514 * Initialize the machine check handler really early to be able to
 515 * catch all machine checks that happen during boot
 516 */
 517arch_initcall(machine_check_init);
 518
 519/*
 520 * Machine checks for the channel subsystem must be enabled
 521 * after the channel subsystem is initialized
 522 */
 523static int __init
 524machine_check_crw_init (void)
 525{
 526        struct task_struct *task;
 527
 528        task = kthread_run(s390_collect_crw_info, &m_sem, "kmcheck");
 529        if (IS_ERR(task))
 530                return PTR_ERR(task);
 531        ctl_set_bit(14, 28);    /* enable channel report MCH */
 532        return 0;
 533}
 534
 535device_initcall (machine_check_crw_init);
 536