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
  25 struct mcck_struct {
  26         int kill_task;
  27         int channel_report;
  28         int warning;
  29         unsigned long long mcck_code;
  30 };
  31
  32 static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
  33
  34 static void s390_handle_damage(char *msg)
  35 {
  36         smp_send_stop();
  37         disabled_wait((unsigned long) __builtin_return_address(0));
  38         while (1);
  39 }
  40
  41 /*
  42  * Main machine check handler function. Will be called with interrupts enabled
  43  * or disabled and machine checks enabled or disabled.
  44  */
  45 void s390_handle_mcck(void)
  46 {
  47         unsigned long flags;
  48         struct mcck_struct mcck;
  49
  50         /*
  51          * Disable machine checks and get the current state of accumulated
  52          * machine checks. Afterwards delete the old state and enable machine
  53          * checks again.
  54          */
  55         local_irq_save(flags);
  56         local_mcck_disable();
  57         /*
  58          * Ummm... Does this make sense at all? Copying the percpu struct
  59          * and then zapping it one statement later?
  60          */
  61         memcpy(&mcck, this_cpu_ptr(&cpu_mcck), sizeof(mcck));
  62         memset(&mcck, 0, sizeof(struct mcck_struct));
  63         clear_cpu_flag(CIF_MCCK_PENDING);
  64         local_mcck_enable();
  65         local_irq_restore(flags);
  66
  67         if (mcck.channel_report)
  68                 crw_handle_channel_report();
  69         /*
  70          * A warning may remain for a prolonged period on the bare iron.
  71          * (actually until the machine is powered off, or the problem is gone)
  72          * So we just stop listening for the WARNING MCH and avoid continuously
  73          * being interrupted.  One caveat is however, that we must do this per
  74          * processor and cannot use the smp version of ctl_clear_bit().
  75          * On VM we only get one interrupt per virtally presented machinecheck.
  76          * Though one suffices, we may get one interrupt per (virtual) cpu.
  77          */
  78         if (mcck.warning) {     /* WARNING pending ? */
  79                 static int mchchk_wng_posted = 0;
  80
  81                 /* Use single cpu clear, as we cannot handle smp here. */
  82                 __ctl_clear_bit(14, 24);        /* Disable WARNING MCH */
  83                 if (xchg(&mchchk_wng_posted, 1) == 0)
  84                         kill_cad_pid(SIGPWR, 1);
  85         }
  86         if (mcck.kill_task) {
  87                 local_irq_enable();
  88                 printk(KERN_EMERG "mcck: Terminating task because of machine "
  89                        "malfunction (code 0x%016llx).\n", mcck.mcck_code);
  90                 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
  91                        current->comm, current->pid);
  92                 do_exit(SIGSEGV);
  93         }
  94 }
  95 EXPORT_SYMBOL_GPL(s390_handle_mcck);
  96
  97 /*
  98  * returns 0 if all registers could be validated
  99  * returns 1 otherwise
 100  */
 101 static int notrace s390_revalidate_registers(struct mci *mci)
 102 {
 103         int kill_task;
 104         u64 zero;
 105         void *fpt_save_area, *fpt_creg_save_area;
 106
 107         kill_task = 0;
 108         zero = 0;
 109
 110         if (!mci->gr) {
 111                 /*
 112                  * General purpose registers couldn't be restored and have
 113                  * unknown contents. Process needs to be terminated.
 114                  */
 115                 kill_task = 1;
 116         }
 117         if (!mci->fp) {
 118                 /*
 119                  * Floating point registers can't be restored and
 120                  * therefore the process needs to be terminated.
 121                  */
 122                 kill_task = 1;
 123         }
 124 #ifndef CONFIG_64BIT
 125         asm volatile(
 126                 "       ld      0,0(%0)\n"
 127                 "       ld      2,8(%0)\n"
 128                 "       ld      4,16(%0)\n"
 129                 "       ld      6,24(%0)"
 130                 : : "a" (&S390_lowcore.floating_pt_save_area));
 131 #endif
 132
 133         if (MACHINE_HAS_IEEE) {
 134 #ifdef CONFIG_64BIT
 135                 fpt_save_area = &S390_lowcore.floating_pt_save_area;
 136                 fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
 137 #else
 138                 fpt_save_area = (void *) S390_lowcore.extended_save_area_addr;
 139                 fpt_creg_save_area = fpt_save_area + 128;
 140 #endif
 141                 if (!mci->fc) {
 142                         /*
 143                          * Floating point control register can't be restored.
 144                          * Task will be terminated.
 145                          */
 146                         asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
 147                         kill_task = 1;
 148
 149                 } else
 150                         asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
 151
 152                 asm volatile(
 153                         "       ld      0,0(%0)\n"
 154                         "       ld      1,8(%0)\n"
 155                         "       ld      2,16(%0)\n"
 156                         "       ld      3,24(%0)\n"
 157                         "       ld      4,32(%0)\n"
 158                         "       ld      5,40(%0)\n"
 159                         "       ld      6,48(%0)\n"
 160                         "       ld      7,56(%0)\n"
 161                         "       ld      8,64(%0)\n"
 162                         "       ld      9,72(%0)\n"
 163                         "       ld      10,80(%0)\n"
 164                         "       ld      11,88(%0)\n"
 165                         "       ld      12,96(%0)\n"
 166                         "       ld      13,104(%0)\n"
 167                         "       ld      14,112(%0)\n"
 168                         "       ld      15,120(%0)\n"
 169                         : : "a" (fpt_save_area));
 170         }
 171
 172 #ifdef CONFIG_64BIT
 173         /* Revalidate vector registers */
 174         if (MACHINE_HAS_VX && current->thread.vxrs) {
 175                 if (!mci->vr) {
 176                         /*
 177                          * Vector registers can't be restored and therefore
 178                          * the process needs to be terminated.
 179                          */
 180                         kill_task = 1;
 181                 }
 182                 restore_vx_regs((__vector128 *)
 183                                 S390_lowcore.vector_save_area_addr);
 184         }
 185 #endif
 186         /* Revalidate access registers */
 187         asm volatile(
 188                 "       lam     0,15,0(%0)"
 189                 : : "a" (&S390_lowcore.access_regs_save_area));
 190         if (!mci->ar) {
 191                 /*
 192                  * Access registers have unknown contents.
 193                  * Terminating task.
 194                  */
 195                 kill_task = 1;
 196         }
 197         /* Revalidate control registers */
 198         if (!mci->cr) {
 199                 /*
 200                  * Control registers have unknown contents.
 201                  * Can't recover and therefore stopping machine.
 202                  */
 203                 s390_handle_damage("invalid control registers.");
 204         } else {
 205 #ifdef CONFIG_64BIT
 206                 asm volatile(
 207                         "       lctlg   0,15,0(%0)"
 208                         : : "a" (&S390_lowcore.cregs_save_area));
 209 #else
 210                 asm volatile(
 211                         "       lctl    0,15,0(%0)"
 212                         : : "a" (&S390_lowcore.cregs_save_area));
 213 #endif
 214         }
 215         /*
 216          * We don't even try to revalidate the TOD register, since we simply
 217          * can't write something sensible into that register.
 218          */
 219 #ifdef CONFIG_64BIT
 220         /*
 221          * See if we can revalidate the TOD programmable register with its
 222          * old contents (should be zero) otherwise set it to zero.
 223          */
 224         if (!mci->pr)
 225                 asm volatile(
 226                         "       sr      0,0\n"
 227                         "       sckpf"
 228                         : : : "0", "cc");
 229         else
 230                 asm volatile(
 231                         "       l       0,0(%0)\n"
 232                         "       sckpf"
 233                         : : "a" (&S390_lowcore.tod_progreg_save_area)
 234                         : "0", "cc");
 235 #endif
 236         /* Revalidate clock comparator register */
 237         set_clock_comparator(S390_lowcore.clock_comparator);
 238         /* Check if old PSW is valid */
 239         if (!mci->wp)
 240                 /*
 241                  * Can't tell if we come from user or kernel mode
 242                  * -> stopping machine.
 243                  */
 244                 s390_handle_damage("old psw invalid.");
 245
 246         if (!mci->ms || !mci->pm || !mci->ia)
 247                 kill_task = 1;
 248
 249         return kill_task;
 250 }
 251
 252 #define MAX_IPD_COUNT   29
 253 #define MAX_IPD_TIME    (5 * 60 * USEC_PER_SEC) /* 5 minutes */
 254
 255 #define ED_STP_ISLAND   6       /* External damage STP island check */
 256 #define ED_STP_SYNC     7       /* External damage STP sync check */
 257 #define ED_ETR_SYNC     12      /* External damage ETR sync check */
 258 #define ED_ETR_SWITCH   13      /* External damage ETR switch to local */
 259
 260 /*
 261  * machine check handler.
 262  */
 263 void notrace s390_do_machine_check(struct pt_regs *regs)
 264 {
 265         static int ipd_count;
 266         static DEFINE_SPINLOCK(ipd_lock);
 267         static unsigned long long last_ipd;
 268         struct mcck_struct *mcck;
 269         unsigned long long tmp;
 270         struct mci *mci;
 271         int umode;
 272
 273         nmi_enter();
 274         inc_irq_stat(NMI_NMI);
 275         mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
 276         mcck = this_cpu_ptr(&cpu_mcck);
 277         umode = user_mode(regs);
 278
 279         if (mci->sd) {
 280                 /* System damage -> stopping machine */
 281                 s390_handle_damage("received system damage machine check.");
 282         }
 283         if (mci->pd) {
 284                 if (mci->b) {
 285                         /* Processing backup -> verify if we can survive this */
 286                         u64 z_mcic, o_mcic, t_mcic;
 287 #ifdef CONFIG_64BIT
 288                         z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
 289                         o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
 290                                   1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
 291                                   1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
 292                                   1ULL<<16);
 293 #else
 294                         z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<57 | 1ULL<<50 |
 295                                   1ULL<<29);
 296                         o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
 297                                   1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
 298                                   1ULL<<30 | 1ULL<<20 | 1ULL<<17 | 1ULL<<16);
 299 #endif
 300                         t_mcic = *(u64 *)mci;
 301
 302                         if (((t_mcic & z_mcic) != 0) ||
 303                             ((t_mcic & o_mcic) != o_mcic)) {
 304                                 s390_handle_damage("processing backup machine "
 305                                                    "check with damage.");
 306                         }
 307
 308                         /*
 309                          * Nullifying exigent condition, therefore we might
 310                          * retry this instruction.
 311                          */
 312                         spin_lock(&ipd_lock);
 313                         tmp = get_tod_clock();
 314                         if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
 315                                 ipd_count++;
 316                         else
 317                                 ipd_count = 1;
 318                         last_ipd = tmp;
 319                         if (ipd_count == MAX_IPD_COUNT)
 320                                 s390_handle_damage("too many ipd retries.");
 321                         spin_unlock(&ipd_lock);
 322                 } else {
 323                         /* Processing damage -> stopping machine */
 324                         s390_handle_damage("received instruction processing "
 325                                            "damage machine check.");
 326                 }
 327         }
 328         if (s390_revalidate_registers(mci)) {
 329                 if (umode) {
 330                         /*
 331                          * Couldn't restore all register contents while in
 332                          * user mode -> mark task for termination.
 333                          */
 334                         mcck->kill_task = 1;
 335                         mcck->mcck_code = *(unsigned long long *) mci;
 336                         set_cpu_flag(CIF_MCCK_PENDING);
 337                 } else {
 338                         /*
 339                          * Couldn't restore all register contents while in
 340                          * kernel mode -> stopping machine.
 341                          */
 342                         s390_handle_damage("unable to revalidate registers.");
 343                 }
 344         }
 345         if (mci->cd) {
 346                 /* Timing facility damage */
 347                 s390_handle_damage("TOD clock damaged");
 348         }
 349         if (mci->ed && mci->ec) {
 350                 /* External damage */
 351                 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
 352                         etr_sync_check();
 353                 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
 354                         etr_switch_to_local();
 355                 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
 356                         stp_sync_check();
 357                 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
 358                         stp_island_check();
 359         }
 360         if (mci->se)
 361                 /* Storage error uncorrected */
 362                 s390_handle_damage("received storage error uncorrected "
 363                                    "machine check.");
 364         if (mci->ke)
 365                 /* Storage key-error uncorrected */
 366                 s390_handle_damage("received storage key-error uncorrected "
 367                                    "machine check.");
 368         if (mci->ds && mci->fa)
 369                 /* Storage degradation */
 370                 s390_handle_damage("received storage degradation machine "
 371                                    "check.");
 372         if (mci->cp) {
 373                 /* Channel report word pending */
 374                 mcck->channel_report = 1;
 375                 set_cpu_flag(CIF_MCCK_PENDING);
 376         }
 377         if (mci->w) {
 378                 /* Warning pending */
 379                 mcck->warning = 1;
 380                 set_cpu_flag(CIF_MCCK_PENDING);
 381         }
 382         nmi_exit();
 383 }
 384
 385 static int __init machine_check_init(void)
 386 {
 387         ctl_set_bit(14, 25);    /* enable external damage MCH */
 388         ctl_set_bit(14, 27);    /* enable system recovery MCH */
 389         ctl_set_bit(14, 24);    /* enable warning MCH */
 390         return 0;
 391 }
 392 arch_initcall(machine_check_init);