arch/s390/kernel/nmi.c

   1 /*
   2  *   Machine check handler
   3  *
   4  *    Copyright IBM Corp. 2000, 2009
   5  *    Author(s): Ingo Adlung <adlung@de.ibm.com>,
   6  *               Martin Schwidefsky <schwidefsky@de.ibm.com>,
   7  *               Cornelia Huck <cornelia.huck@de.ibm.com>,
   8  *               Heiko Carstens <heiko.carstens@de.ibm.com>,
   9  */
  10
  11 #include <linux/kernel_stat.h>
  12 #include <linux/init.h>
  13 #include <linux/errno.h>
  14 #include <linux/hardirq.h>
  15 #include <linux/time.h>
  16 #include <linux/module.h>
  17 #include <asm/lowcore.h>
  18 #include <asm/smp.h>
  19 #include <asm/etr.h>
  20 #include <asm/cputime.h>
  21 #include <asm/nmi.h>
  22 #include <asm/crw.h>
  23
  24 struct mcck_struct {
  25         int kill_task;
  26         int channel_report;
  27         int warning;
  28         unsigned long long mcck_code;
  29 };
  30
  31 static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
  32
  33 static void s390_handle_damage(char *msg)
  34 {
  35         smp_send_stop();
  36         disabled_wait((unsigned long) __builtin_return_address(0));
  37         while (1);
  38 }
  39
  40 /*
  41  * Main machine check handler function. Will be called with interrupts enabled
  42  * or disabled and machine checks enabled or disabled.
  43  */
  44 void s390_handle_mcck(void)
  45 {
  46         unsigned long flags;
  47         struct mcck_struct mcck;
  48
  49         /*
  50          * Disable machine checks and get the current state of accumulated
  51          * machine checks. Afterwards delete the old state and enable machine
  52          * checks again.
  53          */
  54         local_irq_save(flags);
  55         local_mcck_disable();
  56         mcck = __get_cpu_var(cpu_mcck);
  57         memset(&__get_cpu_var(cpu_mcck), 0, sizeof(struct mcck_struct));
  58         clear_thread_flag(TIF_MCCK_PENDING);
  59         local_mcck_enable();
  60         local_irq_restore(flags);
  61
  62         if (mcck.channel_report)
  63                 crw_handle_channel_report();
  64         /*
  65          * A warning may remain for a prolonged period on the bare iron.
  66          * (actually until the machine is powered off, or the problem is gone)
  67          * So we just stop listening for the WARNING MCH and avoid continuously
  68          * being interrupted.  One caveat is however, that we must do this per
  69          * processor and cannot use the smp version of ctl_clear_bit().
  70          * On VM we only get one interrupt per virtally presented machinecheck.
  71          * Though one suffices, we may get one interrupt per (virtual) cpu.
  72          */
  73         if (mcck.warning) {     /* WARNING pending ? */
  74                 static int mchchk_wng_posted = 0;
  75
  76                 /* Use single cpu clear, as we cannot handle smp here. */
  77                 __ctl_clear_bit(14, 24);        /* Disable WARNING MCH */
  78                 if (xchg(&mchchk_wng_posted, 1) == 0)
  79                         kill_cad_pid(SIGPWR, 1);
  80         }
  81         if (mcck.kill_task) {
  82                 local_irq_enable();
  83                 printk(KERN_EMERG "mcck: Terminating task because of machine "
  84                        "malfunction (code 0x%016llx).\n", mcck.mcck_code);
  85                 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
  86                        current->comm, current->pid);
  87                 do_exit(SIGSEGV);
  88         }
  89 }
  90 EXPORT_SYMBOL_GPL(s390_handle_mcck);
  91
  92 /*
  93  * returns 0 if all registers could be validated
  94  * returns 1 otherwise
  95  */
  96 static int notrace s390_revalidate_registers(struct mci *mci)
  97 {
  98         int kill_task;
  99         u64 zero;
 100         void *fpt_save_area, *fpt_creg_save_area;
 101
 102         kill_task = 0;
 103         zero = 0;
 104
 105         if (!mci->gr) {
 106                 /*
 107                  * General purpose registers couldn't be restored and have
 108                  * unknown contents. Process needs to be terminated.
 109                  */
 110                 kill_task = 1;
 111         }
 112         if (!mci->fp) {
 113                 /*
 114                  * Floating point registers can't be restored and
 115                  * therefore the process needs to be terminated.
 116                  */
 117                 kill_task = 1;
 118         }
 119 #ifndef CONFIG_64BIT
 120         asm volatile(
 121                 "       ld      0,0(%0)\n"
 122                 "       ld      2,8(%0)\n"
 123                 "       ld      4,16(%0)\n"
 124                 "       ld      6,24(%0)"
 125                 : : "a" (&S390_lowcore.floating_pt_save_area));
 126 #endif
 127
 128         if (MACHINE_HAS_IEEE) {
 129 #ifdef CONFIG_64BIT
 130                 fpt_save_area = &S390_lowcore.floating_pt_save_area;
 131                 fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
 132 #else
 133                 fpt_save_area = (void *) S390_lowcore.extended_save_area_addr;
 134                 fpt_creg_save_area = fpt_save_area + 128;
 135 #endif
 136                 if (!mci->fc) {
 137                         /*
 138                          * Floating point control register can't be restored.
 139                          * Task will be terminated.
 140                          */
 141                         asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
 142                         kill_task = 1;
 143
 144                 } else
 145                         asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
 146
 147                 asm volatile(
 148                         "       ld      0,0(%0)\n"
 149                         "       ld      1,8(%0)\n"
 150                         "       ld      2,16(%0)\n"
 151                         "       ld      3,24(%0)\n"
 152                         "       ld      4,32(%0)\n"
 153                         "       ld      5,40(%0)\n"
 154                         "       ld      6,48(%0)\n"
 155                         "       ld      7,56(%0)\n"
 156                         "       ld      8,64(%0)\n"
 157                         "       ld      9,72(%0)\n"
 158                         "       ld      10,80(%0)\n"
 159                         "       ld      11,88(%0)\n"
 160                         "       ld      12,96(%0)\n"
 161                         "       ld      13,104(%0)\n"
 162                         "       ld      14,112(%0)\n"
 163                         "       ld      15,120(%0)\n"
 164                         : : "a" (fpt_save_area));
 165         }
 166         /* Revalidate access registers */
 167         asm volatile(
 168                 "       lam     0,15,0(%0)"
 169                 : : "a" (&S390_lowcore.access_regs_save_area));
 170         if (!mci->ar) {
 171                 /*
 172                  * Access registers have unknown contents.
 173                  * Terminating task.
 174                  */
 175                 kill_task = 1;
 176         }
 177         /* Revalidate control registers */
 178         if (!mci->cr) {
 179                 /*
 180                  * Control registers have unknown contents.
 181                  * Can't recover and therefore stopping machine.
 182                  */
 183                 s390_handle_damage("invalid control registers.");
 184         } else {
 185 #ifdef CONFIG_64BIT
 186                 asm volatile(
 187                         "       lctlg   0,15,0(%0)"
 188                         : : "a" (&S390_lowcore.cregs_save_area));
 189 #else
 190                 asm volatile(
 191                         "       lctl    0,15,0(%0)"
 192                         : : "a" (&S390_lowcore.cregs_save_area));
 193 #endif
 194         }
 195         /*
 196          * We don't even try to revalidate the TOD register, since we simply
 197          * can't write something sensible into that register.
 198          */
 199 #ifdef CONFIG_64BIT
 200         /*
 201          * See if we can revalidate the TOD programmable register with its
 202          * old contents (should be zero) otherwise set it to zero.
 203          */
 204         if (!mci->pr)
 205                 asm volatile(
 206                         "       sr      0,0\n"
 207                         "       sckpf"
 208                         : : : "0", "cc");
 209         else
 210                 asm volatile(
 211                         "       l       0,0(%0)\n"
 212                         "       sckpf"
 213                         : : "a" (&S390_lowcore.tod_progreg_save_area)
 214                         : "0", "cc");
 215 #endif
 216         /* Revalidate clock comparator register */
 217         if (S390_lowcore.clock_comparator == -1)
 218                 set_clock_comparator(S390_lowcore.mcck_clock);
 219         else
 220                 set_clock_comparator(S390_lowcore.clock_comparator);
 221         /* Check if old PSW is valid */
 222         if (!mci->wp)
 223                 /*
 224                  * Can't tell if we come from user or kernel mode
 225                  * -> stopping machine.
 226                  */
 227                 s390_handle_damage("old psw invalid.");
 228
 229         if (!mci->ms || !mci->pm || !mci->ia)
 230                 kill_task = 1;
 231
 232         return kill_task;
 233 }
 234
 235 #define MAX_IPD_COUNT   29
 236 #define MAX_IPD_TIME    (5 * 60 * USEC_PER_SEC) /* 5 minutes */
 237
 238 #define ED_STP_ISLAND   6       /* External damage STP island check */
 239 #define ED_STP_SYNC     7       /* External damage STP sync check */
 240 #define ED_ETR_SYNC     12      /* External damage ETR sync check */
 241 #define ED_ETR_SWITCH   13      /* External damage ETR switch to local */
 242
 243 /*
 244  * machine check handler.
 245  */
 246 void notrace s390_do_machine_check(struct pt_regs *regs)
 247 {
 248         static int ipd_count;
 249         static DEFINE_SPINLOCK(ipd_lock);
 250         static unsigned long long last_ipd;
 251         struct mcck_struct *mcck;
 252         unsigned long long tmp;
 253         struct mci *mci;
 254         int umode;
 255
 256         nmi_enter();
 257         kstat_cpu(smp_processor_id()).irqs[NMI_NMI]++;
 258         mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
 259         mcck = &__get_cpu_var(cpu_mcck);
 260         umode = user_mode(regs);
 261
 262         if (mci->sd) {
 263                 /* System damage -> stopping machine */
 264                 s390_handle_damage("received system damage machine check.");
 265         }
 266         if (mci->pd) {
 267                 if (mci->b) {
 268                         /* Processing backup -> verify if we can survive this */
 269                         u64 z_mcic, o_mcic, t_mcic;
 270 #ifdef CONFIG_64BIT
 271                         z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
 272                         o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
 273                                   1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
 274                                   1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
 275                                   1ULL<<16);
 276 #else
 277                         z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<57 | 1ULL<<50 |
 278                                   1ULL<<29);
 279                         o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
 280                                   1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
 281                                   1ULL<<30 | 1ULL<<20 | 1ULL<<17 | 1ULL<<16);
 282 #endif
 283                         t_mcic = *(u64 *)mci;
 284
 285                         if (((t_mcic & z_mcic) != 0) ||
 286                             ((t_mcic & o_mcic) != o_mcic)) {
 287                                 s390_handle_damage("processing backup machine "
 288                                                    "check with damage.");
 289                         }
 290
 291                         /*
 292                          * Nullifying exigent condition, therefore we might
 293                          * retry this instruction.
 294                          */
 295                         spin_lock(&ipd_lock);
 296                         tmp = get_clock();
 297                         if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
 298                                 ipd_count++;
 299                         else
 300                                 ipd_count = 1;
 301                         last_ipd = tmp;
 302                         if (ipd_count == MAX_IPD_COUNT)
 303                                 s390_handle_damage("too many ipd retries.");
 304                         spin_unlock(&ipd_lock);
 305                 } else {
 306                         /* Processing damage -> stopping machine */
 307                         s390_handle_damage("received instruction processing "
 308                                            "damage machine check.");
 309                 }
 310         }
 311         if (s390_revalidate_registers(mci)) {
 312                 if (umode) {
 313                         /*
 314                          * Couldn't restore all register contents while in
 315                          * user mode -> mark task for termination.
 316                          */
 317                         mcck->kill_task = 1;
 318                         mcck->mcck_code = *(unsigned long long *) mci;
 319                         set_thread_flag(TIF_MCCK_PENDING);
 320                 } else {
 321                         /*
 322                          * Couldn't restore all register contents while in
 323                          * kernel mode -> stopping machine.
 324                          */
 325                         s390_handle_damage("unable to revalidate registers.");
 326                 }
 327         }
 328         if (mci->cd) {
 329                 /* Timing facility damage */
 330                 s390_handle_damage("TOD clock damaged");
 331         }
 332         if (mci->ed && mci->ec) {
 333                 /* External damage */
 334                 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
 335                         etr_sync_check();
 336                 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
 337                         etr_switch_to_local();
 338                 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
 339                         stp_sync_check();
 340                 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
 341                         stp_island_check();
 342         }
 343         if (mci->se)
 344                 /* Storage error uncorrected */
 345                 s390_handle_damage("received storage error uncorrected "
 346                                    "machine check.");
 347         if (mci->ke)
 348                 /* Storage key-error uncorrected */
 349                 s390_handle_damage("received storage key-error uncorrected "
 350                                    "machine check.");
 351         if (mci->ds && mci->fa)
 352                 /* Storage degradation */
 353                 s390_handle_damage("received storage degradation machine "
 354                                    "check.");
 355         if (mci->cp) {
 356                 /* Channel report word pending */
 357                 mcck->channel_report = 1;
 358                 set_thread_flag(TIF_MCCK_PENDING);
 359         }
 360         if (mci->w) {
 361                 /* Warning pending */
 362                 mcck->warning = 1;
 363                 set_thread_flag(TIF_MCCK_PENDING);
 364         }
 365         nmi_exit();
 366 }
 367
 368 static int __init machine_check_init(void)
 369 {
 370         ctl_set_bit(14, 25);    /* enable external damage MCH */
 371         ctl_set_bit(14, 27);    /* enable system recovery MCH */
 372         ctl_set_bit(14, 24);    /* enable warning MCH */
 373         return 0;
 374 }
 375 arch_initcall(machine_check_init);