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 #include <asm/switch_to.h>
  24 #include <asm/ctl_reg.h>
  25
  26 struct mcck_struct {
  27         unsigned int kill_task : 1;
  28         unsigned int channel_report : 1;
  29         unsigned int warning : 1;
  30         unsigned int etr_queue : 1;
  31         unsigned int stp_queue : 1;
  32         unsigned long mcck_code;
  33 };
  34
  35 static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
  36
  37 static void s390_handle_damage(void)
  38 {
  39         smp_send_stop();
  40         disabled_wait((unsigned long) __builtin_return_address(0));
  41         while (1);
  42 }
  43
  44 /*
  45  * Main machine check handler function. Will be called with interrupts enabled
  46  * or disabled and machine checks enabled or disabled.
  47  */
  48 void s390_handle_mcck(void)
  49 {
  50         unsigned long flags;
  51         struct mcck_struct mcck;
  52
  53         /*
  54          * Disable machine checks and get the current state of accumulated
  55          * machine checks. Afterwards delete the old state and enable machine
  56          * checks again.
  57          */
  58         local_irq_save(flags);
  59         local_mcck_disable();
  60         mcck = *this_cpu_ptr(&cpu_mcck);
  61         memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
  62         clear_cpu_flag(CIF_MCCK_PENDING);
  63         local_mcck_enable();
  64         local_irq_restore(flags);
  65
  66         if (mcck.channel_report)
  67                 crw_handle_channel_report();
  68         /*
  69          * A warning may remain for a prolonged period on the bare iron.
  70          * (actually until the machine is powered off, or the problem is gone)
  71          * So we just stop listening for the WARNING MCH and avoid continuously
  72          * being interrupted.  One caveat is however, that we must do this per
  73          * processor and cannot use the smp version of ctl_clear_bit().
  74          * On VM we only get one interrupt per virtally presented machinecheck.
  75          * Though one suffices, we may get one interrupt per (virtual) cpu.
  76          */
  77         if (mcck.warning) {     /* WARNING pending ? */
  78                 static int mchchk_wng_posted = 0;
  79
  80                 /* Use single cpu clear, as we cannot handle smp here. */
  81                 __ctl_clear_bit(14, 24);        /* Disable WARNING MCH */
  82                 if (xchg(&mchchk_wng_posted, 1) == 0)
  83                         kill_cad_pid(SIGPWR, 1);
  84         }
  85         if (mcck.etr_queue)
  86                 etr_queue_work();
  87         if (mcck.stp_queue)
  88                 stp_queue_work();
  89         if (mcck.kill_task) {
  90                 local_irq_enable();
  91                 printk(KERN_EMERG "mcck: Terminating task because of machine "
  92                        "malfunction (code 0x%016lx).\n", mcck.mcck_code);
  93                 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
  94                        current->comm, current->pid);
  95                 do_exit(SIGSEGV);
  96         }
  97 }
  98 EXPORT_SYMBOL_GPL(s390_handle_mcck);
  99
 100 /*
 101  * returns 0 if all registers could be validated
 102  * returns 1 otherwise
 103  */
 104 static int notrace s390_validate_registers(union mci mci)
 105 {
 106         int kill_task;
 107         u64 zero;
 108         void *fpt_save_area, *fpt_creg_save_area;
 109
 110         kill_task = 0;
 111         zero = 0;
 112
 113         if (!mci.gr) {
 114                 /*
 115                  * General purpose registers couldn't be restored and have
 116                  * unknown contents. Process needs to be terminated.
 117                  */
 118                 kill_task = 1;
 119         }
 120         if (!mci.fp) {
 121                 /*
 122                  * Floating point registers can't be restored and
 123                  * therefore the process needs to be terminated.
 124                  */
 125                 kill_task = 1;
 126         }
 127         fpt_save_area = &S390_lowcore.floating_pt_save_area;
 128         fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
 129         if (!mci.fc) {
 130                 /*
 131                  * Floating point control register can't be restored.
 132                  * Task will be terminated.
 133                  */
 134                 asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
 135                 kill_task = 1;
 136         } else
 137                 asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
 138
 139         if (!MACHINE_HAS_VX) {
 140                 /* Validate floating point registers */
 141                 asm volatile(
 142                         "       ld      0,0(%0)\n"
 143                         "       ld      1,8(%0)\n"
 144                         "       ld      2,16(%0)\n"
 145                         "       ld      3,24(%0)\n"
 146                         "       ld      4,32(%0)\n"
 147                         "       ld      5,40(%0)\n"
 148                         "       ld      6,48(%0)\n"
 149                         "       ld      7,56(%0)\n"
 150                         "       ld      8,64(%0)\n"
 151                         "       ld      9,72(%0)\n"
 152                         "       ld      10,80(%0)\n"
 153                         "       ld      11,88(%0)\n"
 154                         "       ld      12,96(%0)\n"
 155                         "       ld      13,104(%0)\n"
 156                         "       ld      14,112(%0)\n"
 157                         "       ld      15,120(%0)\n"
 158                         : : "a" (fpt_save_area));
 159         } else {
 160                 /* Validate vector registers */
 161                 union ctlreg0 cr0;
 162
 163                 if (!mci.vr) {
 164                         /*
 165                          * Vector registers can't be restored and therefore
 166                          * the process needs to be terminated.
 167                          */
 168                         kill_task = 1;
 169                 }
 170                 cr0.val = S390_lowcore.cregs_save_area[0];
 171                 cr0.afp = cr0.vx = 1;
 172                 __ctl_load(cr0.val, 0, 0);
 173                 asm volatile(
 174                         "       la      1,%0\n"
 175                         "       .word   0xe70f,0x1000,0x0036\n" /* vlm 0,15,0(1) */
 176                         "       .word   0xe70f,0x1100,0x0c36\n" /* vlm 16,31,256(1) */
 177                         : : "Q" (*(struct vx_array *)
 178                                  &S390_lowcore.vector_save_area) : "1");
 179                 __ctl_load(S390_lowcore.cregs_save_area[0], 0, 0);
 180         }
 181         /* Validate access registers */
 182         asm volatile(
 183                 "       lam     0,15,0(%0)"
 184                 : : "a" (&S390_lowcore.access_regs_save_area));
 185         if (!mci.ar) {
 186                 /*
 187                  * Access registers have unknown contents.
 188                  * Terminating task.
 189                  */
 190                 kill_task = 1;
 191         }
 192         /* Validate control registers */
 193         if (!mci.cr) {
 194                 /*
 195                  * Control registers have unknown contents.
 196                  * Can't recover and therefore stopping machine.
 197                  */
 198                 s390_handle_damage();
 199         } else {
 200                 asm volatile(
 201                         "       lctlg   0,15,0(%0)"
 202                         : : "a" (&S390_lowcore.cregs_save_area));
 203         }
 204         /*
 205          * We don't even try to validate the TOD register, since we simply
 206          * can't write something sensible into that register.
 207          */
 208         /*
 209          * See if we can validate the TOD programmable register with its
 210          * old contents (should be zero) otherwise set it to zero.
 211          */
 212         if (!mci.pr)
 213                 asm volatile(
 214                         "       sr      0,0\n"
 215                         "       sckpf"
 216                         : : : "0", "cc");
 217         else
 218                 asm volatile(
 219                         "       l       0,0(%0)\n"
 220                         "       sckpf"
 221                         : : "a" (&S390_lowcore.tod_progreg_save_area)
 222                         : "0", "cc");
 223         /* Validate clock comparator register */
 224         set_clock_comparator(S390_lowcore.clock_comparator);
 225         /* Check if old PSW is valid */
 226         if (!mci.wp)
 227                 /*
 228                  * Can't tell if we come from user or kernel mode
 229                  * -> stopping machine.
 230                  */
 231                 s390_handle_damage();
 232
 233         if (!mci.ms || !mci.pm || !mci.ia)
 234                 kill_task = 1;
 235
 236         return kill_task;
 237 }
 238
 239 #define MAX_IPD_COUNT   29
 240 #define MAX_IPD_TIME    (5 * 60 * USEC_PER_SEC) /* 5 minutes */
 241
 242 #define ED_STP_ISLAND   6       /* External damage STP island check */
 243 #define ED_STP_SYNC     7       /* External damage STP sync check */
 244 #define ED_ETR_SYNC     12      /* External damage ETR sync check */
 245 #define ED_ETR_SWITCH   13      /* External damage ETR switch to local */
 246
 247 /*
 248  * machine check handler.
 249  */
 250 void notrace s390_do_machine_check(struct pt_regs *regs)
 251 {
 252         static int ipd_count;
 253         static DEFINE_SPINLOCK(ipd_lock);
 254         static unsigned long long last_ipd;
 255         struct mcck_struct *mcck;
 256         unsigned long long tmp;
 257         union mci mci;
 258         int umode;
 259
 260         nmi_enter();
 261         inc_irq_stat(NMI_NMI);
 262         mci.val = S390_lowcore.mcck_interruption_code;
 263         mcck = this_cpu_ptr(&cpu_mcck);
 264         umode = user_mode(regs);
 265
 266         if (mci.sd) {
 267                 /* System damage -> stopping machine */
 268                 s390_handle_damage();
 269         }
 270         if (mci.pd) {
 271                 if (mci.b) {
 272                         /* Processing backup -> verify if we can survive this */
 273                         u64 z_mcic, o_mcic, t_mcic;
 274                         z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
 275                         o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
 276                                   1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
 277                                   1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
 278                                   1ULL<<16);
 279                         t_mcic = mci.val;
 280
 281                         if (((t_mcic & z_mcic) != 0) ||
 282                             ((t_mcic & o_mcic) != o_mcic)) {
 283                                 s390_handle_damage();
 284                         }
 285
 286                         /*
 287                          * Nullifying exigent condition, therefore we might
 288                          * retry this instruction.
 289                          */
 290                         spin_lock(&ipd_lock);
 291                         tmp = get_tod_clock();
 292                         if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
 293                                 ipd_count++;
 294                         else
 295                                 ipd_count = 1;
 296                         last_ipd = tmp;
 297                         if (ipd_count == MAX_IPD_COUNT)
 298                                 s390_handle_damage();
 299                         spin_unlock(&ipd_lock);
 300                 } else {
 301                         /* Processing damage -> stopping machine */
 302                         s390_handle_damage();
 303                 }
 304         }
 305         if (s390_validate_registers(mci)) {
 306                 if (umode) {
 307                         /*
 308                          * Couldn't restore all register contents while in
 309                          * user mode -> mark task for termination.
 310                          */
 311                         mcck->kill_task = 1;
 312                         mcck->mcck_code = mci.val;
 313                         set_cpu_flag(CIF_MCCK_PENDING);
 314                 } else {
 315                         /*
 316                          * Couldn't restore all register contents while in
 317                          * kernel mode -> stopping machine.
 318                          */
 319                         s390_handle_damage();
 320                 }
 321         }
 322         if (mci.cd) {
 323                 /* Timing facility damage */
 324                 s390_handle_damage();
 325         }
 326         if (mci.ed && mci.ec) {
 327                 /* External damage */
 328                 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
 329                         mcck->etr_queue |= etr_sync_check();
 330                 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
 331                         mcck->etr_queue |= etr_switch_to_local();
 332                 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
 333                         mcck->stp_queue |= stp_sync_check();
 334                 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
 335                         mcck->stp_queue |= stp_island_check();
 336                 if (mcck->etr_queue || mcck->stp_queue)
 337                         set_cpu_flag(CIF_MCCK_PENDING);
 338         }
 339         if (mci.se)
 340                 /* Storage error uncorrected */
 341                 s390_handle_damage();
 342         if (mci.ke)
 343                 /* Storage key-error uncorrected */
 344                 s390_handle_damage();
 345         if (mci.ds && mci.fa)
 346                 /* Storage degradation */
 347                 s390_handle_damage();
 348         if (mci.cp) {
 349                 /* Channel report word pending */
 350                 mcck->channel_report = 1;
 351                 set_cpu_flag(CIF_MCCK_PENDING);
 352         }
 353         if (mci.w) {
 354                 /* Warning pending */
 355                 mcck->warning = 1;
 356                 set_cpu_flag(CIF_MCCK_PENDING);
 357         }
 358         nmi_exit();
 359 }
 360
 361 static int __init machine_check_init(void)
 362 {
 363         ctl_set_bit(14, 25);    /* enable external damage MCH */
 364         ctl_set_bit(14, 27);    /* enable system recovery MCH */
 365         ctl_set_bit(14, 24);    /* enable warning MCH */
 366         return 0;
 367 }
 368 early_initcall(machine_check_init);