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/fpu-internal.h>
  25 #include <asm/ctl_reg.h>
  26
  27 struct mcck_struct {
  28         int kill_task;
  29         int channel_report;
  30         int warning;
  31         unsigned long long mcck_code;
  32 };
  33
  34 static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
  35
  36 static void s390_handle_damage(char *msg)
  37 {
  38         smp_send_stop();
  39         disabled_wait((unsigned long) __builtin_return_address(0));
  40         while (1);
  41 }
  42
  43 /*
  44  * Main machine check handler function. Will be called with interrupts enabled
  45  * or disabled and machine checks enabled or disabled.
  46  */
  47 void s390_handle_mcck(void)
  48 {
  49         unsigned long flags;
  50         struct mcck_struct mcck;
  51
  52         /*
  53          * Disable machine checks and get the current state of accumulated
  54          * machine checks. Afterwards delete the old state and enable machine
  55          * checks again.
  56          */
  57         local_irq_save(flags);
  58         local_mcck_disable();
  59         mcck = *this_cpu_ptr(&cpu_mcck);
  60         memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
  61         clear_cpu_flag(CIF_MCCK_PENDING);
  62         local_mcck_enable();
  63         local_irq_restore(flags);
  64
  65         if (mcck.channel_report)
  66                 crw_handle_channel_report();
  67         /*
  68          * A warning may remain for a prolonged period on the bare iron.
  69          * (actually until the machine is powered off, or the problem is gone)
  70          * So we just stop listening for the WARNING MCH and avoid continuously
  71          * being interrupted.  One caveat is however, that we must do this per
  72          * processor and cannot use the smp version of ctl_clear_bit().
  73          * On VM we only get one interrupt per virtally presented machinecheck.
  74          * Though one suffices, we may get one interrupt per (virtual) cpu.
  75          */
  76         if (mcck.warning) {     /* WARNING pending ? */
  77                 static int mchchk_wng_posted = 0;
  78
  79                 /* Use single cpu clear, as we cannot handle smp here. */
  80                 __ctl_clear_bit(14, 24);        /* Disable WARNING MCH */
  81                 if (xchg(&mchchk_wng_posted, 1) == 0)
  82                         kill_cad_pid(SIGPWR, 1);
  83         }
  84         if (mcck.kill_task) {
  85                 local_irq_enable();
  86                 printk(KERN_EMERG "mcck: Terminating task because of machine "
  87                        "malfunction (code 0x%016llx).\n", mcck.mcck_code);
  88                 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
  89                        current->comm, current->pid);
  90                 do_exit(SIGSEGV);
  91         }
  92 }
  93 EXPORT_SYMBOL_GPL(s390_handle_mcck);
  94
  95 /*
  96  * returns 0 if all registers could be validated
  97  * returns 1 otherwise
  98  */
  99 static int notrace s390_revalidate_registers(struct mci *mci)
 100 {
 101         int kill_task;
 102         u64 zero;
 103         void *fpt_save_area, *fpt_creg_save_area;
 104
 105         kill_task = 0;
 106         zero = 0;
 107
 108         if (!mci->gr) {
 109                 /*
 110                  * General purpose registers couldn't be restored and have
 111                  * unknown contents. Process needs to be terminated.
 112                  */
 113                 kill_task = 1;
 114         }
 115         if (!mci->fp) {
 116                 /*
 117                  * Floating point registers can't be restored and
 118                  * therefore the process needs to be terminated.
 119                  */
 120                 kill_task = 1;
 121         }
 122         fpt_save_area = &S390_lowcore.floating_pt_save_area;
 123         fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
 124         if (!mci->fc) {
 125                 /*
 126                  * Floating point control register can't be restored.
 127                  * Task will be terminated.
 128                  */
 129                 asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
 130                 kill_task = 1;
 131         } else
 132                 asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
 133
 134         if (!MACHINE_HAS_VX) {
 135                 /* Revalidate floating point registers */
 136                 asm volatile(
 137                         "       ld      0,0(%0)\n"
 138                         "       ld      1,8(%0)\n"
 139                         "       ld      2,16(%0)\n"
 140                         "       ld      3,24(%0)\n"
 141                         "       ld      4,32(%0)\n"
 142                         "       ld      5,40(%0)\n"
 143                         "       ld      6,48(%0)\n"
 144                         "       ld      7,56(%0)\n"
 145                         "       ld      8,64(%0)\n"
 146                         "       ld      9,72(%0)\n"
 147                         "       ld      10,80(%0)\n"
 148                         "       ld      11,88(%0)\n"
 149                         "       ld      12,96(%0)\n"
 150                         "       ld      13,104(%0)\n"
 151                         "       ld      14,112(%0)\n"
 152                         "       ld      15,120(%0)\n"
 153                         : : "a" (fpt_save_area));
 154         } else {
 155                 /* Revalidate vector registers */
 156                 union ctlreg0 cr0;
 157
 158                 if (!mci->vr) {
 159                         /*
 160                          * Vector registers can't be restored and therefore
 161                          * the process needs to be terminated.
 162                          */
 163                         kill_task = 1;
 164                 }
 165                 cr0.val = S390_lowcore.cregs_save_area[0];
 166                 cr0.afp = cr0.vx = 1;
 167                 __ctl_load(cr0.val, 0, 0);
 168                 asm volatile(
 169                         "       la      1,%0\n"
 170                         "       .word   0xe70f,0x1000,0x0036\n" /* vlm 0,15,0(1) */
 171                         "       .word   0xe70f,0x1100,0x0c36\n" /* vlm 16,31,256(1) */
 172                         : : "Q" (*(struct vx_array *)
 173                                  &S390_lowcore.vector_save_area) : "1");
 174                 __ctl_load(S390_lowcore.cregs_save_area[0], 0, 0);
 175         }
 176         /* Revalidate access registers */
 177         asm volatile(
 178                 "       lam     0,15,0(%0)"
 179                 : : "a" (&S390_lowcore.access_regs_save_area));
 180         if (!mci->ar) {
 181                 /*
 182                  * Access registers have unknown contents.
 183                  * Terminating task.
 184                  */
 185                 kill_task = 1;
 186         }
 187         /* Revalidate control registers */
 188         if (!mci->cr) {
 189                 /*
 190                  * Control registers have unknown contents.
 191                  * Can't recover and therefore stopping machine.
 192                  */
 193                 s390_handle_damage("invalid control registers.");
 194         } else {
 195                 asm volatile(
 196                         "       lctlg   0,15,0(%0)"
 197                         : : "a" (&S390_lowcore.cregs_save_area));
 198         }
 199         /*
 200          * We don't even try to revalidate the TOD register, since we simply
 201          * can't write something sensible into that register.
 202          */
 203         /*
 204          * See if we can revalidate the TOD programmable register with its
 205          * old contents (should be zero) otherwise set it to zero.
 206          */
 207         if (!mci->pr)
 208                 asm volatile(
 209                         "       sr      0,0\n"
 210                         "       sckpf"
 211                         : : : "0", "cc");
 212         else
 213                 asm volatile(
 214                         "       l       0,0(%0)\n"
 215                         "       sckpf"
 216                         : : "a" (&S390_lowcore.tod_progreg_save_area)
 217                         : "0", "cc");
 218         /* Revalidate clock comparator register */
 219         set_clock_comparator(S390_lowcore.clock_comparator);
 220         /* Check if old PSW is valid */
 221         if (!mci->wp)
 222                 /*
 223                  * Can't tell if we come from user or kernel mode
 224                  * -> stopping machine.
 225                  */
 226                 s390_handle_damage("old psw invalid.");
 227
 228         if (!mci->ms || !mci->pm || !mci->ia)
 229                 kill_task = 1;
 230
 231         return kill_task;
 232 }
 233
 234 #define MAX_IPD_COUNT   29
 235 #define MAX_IPD_TIME    (5 * 60 * USEC_PER_SEC) /* 5 minutes */
 236
 237 #define ED_STP_ISLAND   6       /* External damage STP island check */
 238 #define ED_STP_SYNC     7       /* External damage STP sync check */
 239 #define ED_ETR_SYNC     12      /* External damage ETR sync check */
 240 #define ED_ETR_SWITCH   13      /* External damage ETR switch to local */
 241
 242 /*
 243  * machine check handler.
 244  */
 245 void notrace s390_do_machine_check(struct pt_regs *regs)
 246 {
 247         static int ipd_count;
 248         static DEFINE_SPINLOCK(ipd_lock);
 249         static unsigned long long last_ipd;
 250         struct mcck_struct *mcck;
 251         unsigned long long tmp;
 252         struct mci *mci;
 253         int umode;
 254
 255         nmi_enter();
 256         inc_irq_stat(NMI_NMI);
 257         mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
 258         mcck = this_cpu_ptr(&cpu_mcck);
 259         umode = user_mode(regs);
 260
 261         if (mci->sd) {
 262                 /* System damage -> stopping machine */
 263                 s390_handle_damage("received system damage machine check.");
 264         }
 265         if (mci->pd) {
 266                 if (mci->b) {
 267                         /* Processing backup -> verify if we can survive this */
 268                         u64 z_mcic, o_mcic, t_mcic;
 269                         z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
 270                         o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
 271                                   1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
 272                                   1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
 273                                   1ULL<<16);
 274                         t_mcic = *(u64 *)mci;
 275
 276                         if (((t_mcic & z_mcic) != 0) ||
 277                             ((t_mcic & o_mcic) != o_mcic)) {
 278                                 s390_handle_damage("processing backup machine "
 279                                                    "check with damage.");
 280                         }
 281
 282                         /*
 283                          * Nullifying exigent condition, therefore we might
 284                          * retry this instruction.
 285                          */
 286                         spin_lock(&ipd_lock);
 287                         tmp = get_tod_clock();
 288                         if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
 289                                 ipd_count++;
 290                         else
 291                                 ipd_count = 1;
 292                         last_ipd = tmp;
 293                         if (ipd_count == MAX_IPD_COUNT)
 294                                 s390_handle_damage("too many ipd retries.");
 295                         spin_unlock(&ipd_lock);
 296                 } else {
 297                         /* Processing damage -> stopping machine */
 298                         s390_handle_damage("received instruction processing "
 299                                            "damage machine check.");
 300                 }
 301         }
 302         if (s390_revalidate_registers(mci)) {
 303                 if (umode) {
 304                         /*
 305                          * Couldn't restore all register contents while in
 306                          * user mode -> mark task for termination.
 307                          */
 308                         mcck->kill_task = 1;
 309                         mcck->mcck_code = *(unsigned long long *) mci;
 310                         set_cpu_flag(CIF_MCCK_PENDING);
 311                 } else {
 312                         /*
 313                          * Couldn't restore all register contents while in
 314                          * kernel mode -> stopping machine.
 315                          */
 316                         s390_handle_damage("unable to revalidate registers.");
 317                 }
 318         }
 319         if (mci->cd) {
 320                 /* Timing facility damage */
 321                 s390_handle_damage("TOD clock damaged");
 322         }
 323         if (mci->ed && mci->ec) {
 324                 /* External damage */
 325                 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
 326                         etr_sync_check();
 327                 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
 328                         etr_switch_to_local();
 329                 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
 330                         stp_sync_check();
 331                 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
 332                         stp_island_check();
 333         }
 334         if (mci->se)
 335                 /* Storage error uncorrected */
 336                 s390_handle_damage("received storage error uncorrected "
 337                                    "machine check.");
 338         if (mci->ke)
 339                 /* Storage key-error uncorrected */
 340                 s390_handle_damage("received storage key-error uncorrected "
 341                                    "machine check.");
 342         if (mci->ds && mci->fa)
 343                 /* Storage degradation */
 344                 s390_handle_damage("received storage degradation machine "
 345                                    "check.");
 346         if (mci->cp) {
 347                 /* Channel report word pending */
 348                 mcck->channel_report = 1;
 349                 set_cpu_flag(CIF_MCCK_PENDING);
 350         }
 351         if (mci->w) {
 352                 /* Warning pending */
 353                 mcck->warning = 1;
 354                 set_cpu_flag(CIF_MCCK_PENDING);
 355         }
 356         nmi_exit();
 357 }
 358
 359 static int __init machine_check_init(void)
 360 {
 361         ctl_set_bit(14, 25);    /* enable external damage MCH */
 362         ctl_set_bit(14, 27);    /* enable system recovery MCH */
 363         ctl_set_bit(14, 24);    /* enable warning MCH */
 364         return 0;
 365 }
 366 early_initcall(machine_check_init);