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         int kill_task;
  28         int channel_report;
  29         int warning;
  30         unsigned long long mcck_code;
  31 };
  32
  33 static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
  34
  35 static void s390_handle_damage(char *msg)
  36 {
  37         smp_send_stop();
  38         disabled_wait((unsigned long) __builtin_return_address(0));
  39         while (1);
  40 }
  41
  42 /*
  43  * Main machine check handler function. Will be called with interrupts enabled
  44  * or disabled and machine checks enabled or disabled.
  45  */
  46 void s390_handle_mcck(void)
  47 {
  48         unsigned long flags;
  49         struct mcck_struct mcck;
  50
  51         /*
  52          * Disable machine checks and get the current state of accumulated
  53          * machine checks. Afterwards delete the old state and enable machine
  54          * checks again.
  55          */
  56         local_irq_save(flags);
  57         local_mcck_disable();
  58         mcck = *this_cpu_ptr(&cpu_mcck);
  59         memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
  60         clear_cpu_flag(CIF_MCCK_PENDING);
  61         local_mcck_enable();
  62         local_irq_restore(flags);
  63
  64         if (mcck.channel_report)
  65                 crw_handle_channel_report();
  66         /*
  67          * A warning may remain for a prolonged period on the bare iron.
  68          * (actually until the machine is powered off, or the problem is gone)
  69          * So we just stop listening for the WARNING MCH and avoid continuously
  70          * being interrupted.  One caveat is however, that we must do this per
  71          * processor and cannot use the smp version of ctl_clear_bit().
  72          * On VM we only get one interrupt per virtally presented machinecheck.
  73          * Though one suffices, we may get one interrupt per (virtual) cpu.
  74          */
  75         if (mcck.warning) {     /* WARNING pending ? */
  76                 static int mchchk_wng_posted = 0;
  77
  78                 /* Use single cpu clear, as we cannot handle smp here. */
  79                 __ctl_clear_bit(14, 24);        /* Disable WARNING MCH */
  80                 if (xchg(&mchchk_wng_posted, 1) == 0)
  81                         kill_cad_pid(SIGPWR, 1);
  82         }
  83         if (mcck.kill_task) {
  84                 local_irq_enable();
  85                 printk(KERN_EMERG "mcck: Terminating task because of machine "
  86                        "malfunction (code 0x%016llx).\n", mcck.mcck_code);
  87                 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
  88                        current->comm, current->pid);
  89                 do_exit(SIGSEGV);
  90         }
  91 }
  92 EXPORT_SYMBOL_GPL(s390_handle_mcck);
  93
  94 /*
  95  * returns 0 if all registers could be validated
  96  * returns 1 otherwise
  97  */
  98 static int notrace s390_revalidate_registers(struct mci *mci)
  99 {
 100         int kill_task;
 101         u64 zero;
 102         void *fpt_save_area, *fpt_creg_save_area;
 103
 104         kill_task = 0;
 105         zero = 0;
 106
 107         if (!mci->gr) {
 108                 /*
 109                  * General purpose registers couldn't be restored and have
 110                  * unknown contents. Process needs to be terminated.
 111                  */
 112                 kill_task = 1;
 113         }
 114         if (!mci->fp) {
 115                 /*
 116                  * Floating point registers can't be restored and
 117                  * therefore the process needs to be terminated.
 118                  */
 119                 kill_task = 1;
 120         }
 121         fpt_save_area = &S390_lowcore.floating_pt_save_area;
 122         fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
 123         if (!mci->fc) {
 124                 /*
 125                  * Floating point control register can't be restored.
 126                  * Task will be terminated.
 127                  */
 128                 asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
 129                 kill_task = 1;
 130         } else
 131                 asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
 132
 133         if (!MACHINE_HAS_VX) {
 134                 /* Revalidate floating point registers */
 135                 asm volatile(
 136                         "       ld      0,0(%0)\n"
 137                         "       ld      1,8(%0)\n"
 138                         "       ld      2,16(%0)\n"
 139                         "       ld      3,24(%0)\n"
 140                         "       ld      4,32(%0)\n"
 141                         "       ld      5,40(%0)\n"
 142                         "       ld      6,48(%0)\n"
 143                         "       ld      7,56(%0)\n"
 144                         "       ld      8,64(%0)\n"
 145                         "       ld      9,72(%0)\n"
 146                         "       ld      10,80(%0)\n"
 147                         "       ld      11,88(%0)\n"
 148                         "       ld      12,96(%0)\n"
 149                         "       ld      13,104(%0)\n"
 150                         "       ld      14,112(%0)\n"
 151                         "       ld      15,120(%0)\n"
 152                         : : "a" (fpt_save_area));
 153         } else {
 154                 /* Revalidate vector registers */
 155                 union ctlreg0 cr0;
 156
 157                 if (!mci->vr) {
 158                         /*
 159                          * Vector registers can't be restored and therefore
 160                          * the process needs to be terminated.
 161                          */
 162                         kill_task = 1;
 163                 }
 164                 cr0.val = S390_lowcore.cregs_save_area[0];
 165                 cr0.afp = cr0.vx = 1;
 166                 __ctl_load(cr0.val, 0, 0);
 167                 restore_vx_regs((__vector128 *)
 168                                 &S390_lowcore.vector_save_area);
 169                 __ctl_load(S390_lowcore.cregs_save_area[0], 0, 0);
 170         }
 171         /* Revalidate access registers */
 172         asm volatile(
 173                 "       lam     0,15,0(%0)"
 174                 : : "a" (&S390_lowcore.access_regs_save_area));
 175         if (!mci->ar) {
 176                 /*
 177                  * Access registers have unknown contents.
 178                  * Terminating task.
 179                  */
 180                 kill_task = 1;
 181         }
 182         /* Revalidate control registers */
 183         if (!mci->cr) {
 184                 /*
 185                  * Control registers have unknown contents.
 186                  * Can't recover and therefore stopping machine.
 187                  */
 188                 s390_handle_damage("invalid control registers.");
 189         } else {
 190                 asm volatile(
 191                         "       lctlg   0,15,0(%0)"
 192                         : : "a" (&S390_lowcore.cregs_save_area));
 193         }
 194         /*
 195          * We don't even try to revalidate the TOD register, since we simply
 196          * can't write something sensible into that register.
 197          */
 198         /*
 199          * See if we can revalidate the TOD programmable register with its
 200          * old contents (should be zero) otherwise set it to zero.
 201          */
 202         if (!mci->pr)
 203                 asm volatile(
 204                         "       sr      0,0\n"
 205                         "       sckpf"
 206                         : : : "0", "cc");
 207         else
 208                 asm volatile(
 209                         "       l       0,0(%0)\n"
 210                         "       sckpf"
 211                         : : "a" (&S390_lowcore.tod_progreg_save_area)
 212                         : "0", "cc");
 213         /* Revalidate clock comparator register */
 214         set_clock_comparator(S390_lowcore.clock_comparator);
 215         /* Check if old PSW is valid */
 216         if (!mci->wp)
 217                 /*
 218                  * Can't tell if we come from user or kernel mode
 219                  * -> stopping machine.
 220                  */
 221                 s390_handle_damage("old psw invalid.");
 222
 223         if (!mci->ms || !mci->pm || !mci->ia)
 224                 kill_task = 1;
 225
 226         return kill_task;
 227 }
 228
 229 #define MAX_IPD_COUNT   29
 230 #define MAX_IPD_TIME    (5 * 60 * USEC_PER_SEC) /* 5 minutes */
 231
 232 #define ED_STP_ISLAND   6       /* External damage STP island check */
 233 #define ED_STP_SYNC     7       /* External damage STP sync check */
 234 #define ED_ETR_SYNC     12      /* External damage ETR sync check */
 235 #define ED_ETR_SWITCH   13      /* External damage ETR switch to local */
 236
 237 /*
 238  * machine check handler.
 239  */
 240 void notrace s390_do_machine_check(struct pt_regs *regs)
 241 {
 242         static int ipd_count;
 243         static DEFINE_SPINLOCK(ipd_lock);
 244         static unsigned long long last_ipd;
 245         struct mcck_struct *mcck;
 246         unsigned long long tmp;
 247         struct mci *mci;
 248         int umode;
 249
 250         nmi_enter();
 251         inc_irq_stat(NMI_NMI);
 252         mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
 253         mcck = this_cpu_ptr(&cpu_mcck);
 254         umode = user_mode(regs);
 255
 256         if (mci->sd) {
 257                 /* System damage -> stopping machine */
 258                 s390_handle_damage("received system damage machine check.");
 259         }
 260         if (mci->pd) {
 261                 if (mci->b) {
 262                         /* Processing backup -> verify if we can survive this */
 263                         u64 z_mcic, o_mcic, t_mcic;
 264                         z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
 265                         o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
 266                                   1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
 267                                   1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
 268                                   1ULL<<16);
 269                         t_mcic = *(u64 *)mci;
 270
 271                         if (((t_mcic & z_mcic) != 0) ||
 272                             ((t_mcic & o_mcic) != o_mcic)) {
 273                                 s390_handle_damage("processing backup machine "
 274                                                    "check with damage.");
 275                         }
 276
 277                         /*
 278                          * Nullifying exigent condition, therefore we might
 279                          * retry this instruction.
 280                          */
 281                         spin_lock(&ipd_lock);
 282                         tmp = get_tod_clock();
 283                         if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
 284                                 ipd_count++;
 285                         else
 286                                 ipd_count = 1;
 287                         last_ipd = tmp;
 288                         if (ipd_count == MAX_IPD_COUNT)
 289                                 s390_handle_damage("too many ipd retries.");
 290                         spin_unlock(&ipd_lock);
 291                 } else {
 292                         /* Processing damage -> stopping machine */
 293                         s390_handle_damage("received instruction processing "
 294                                            "damage machine check.");
 295                 }
 296         }
 297         if (s390_revalidate_registers(mci)) {
 298                 if (umode) {
 299                         /*
 300                          * Couldn't restore all register contents while in
 301                          * user mode -> mark task for termination.
 302                          */
 303                         mcck->kill_task = 1;
 304                         mcck->mcck_code = *(unsigned long long *) mci;
 305                         set_cpu_flag(CIF_MCCK_PENDING);
 306                 } else {
 307                         /*
 308                          * Couldn't restore all register contents while in
 309                          * kernel mode -> stopping machine.
 310                          */
 311                         s390_handle_damage("unable to revalidate registers.");
 312                 }
 313         }
 314         if (mci->cd) {
 315                 /* Timing facility damage */
 316                 s390_handle_damage("TOD clock damaged");
 317         }
 318         if (mci->ed && mci->ec) {
 319                 /* External damage */
 320                 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
 321                         etr_sync_check();
 322                 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
 323                         etr_switch_to_local();
 324                 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
 325                         stp_sync_check();
 326                 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
 327                         stp_island_check();
 328         }
 329         if (mci->se)
 330                 /* Storage error uncorrected */
 331                 s390_handle_damage("received storage error uncorrected "
 332                                    "machine check.");
 333         if (mci->ke)
 334                 /* Storage key-error uncorrected */
 335                 s390_handle_damage("received storage key-error uncorrected "
 336                                    "machine check.");
 337         if (mci->ds && mci->fa)
 338                 /* Storage degradation */
 339                 s390_handle_damage("received storage degradation machine "
 340                                    "check.");
 341         if (mci->cp) {
 342                 /* Channel report word pending */
 343                 mcck->channel_report = 1;
 344                 set_cpu_flag(CIF_MCCK_PENDING);
 345         }
 346         if (mci->w) {
 347                 /* Warning pending */
 348                 mcck->warning = 1;
 349                 set_cpu_flag(CIF_MCCK_PENDING);
 350         }
 351         nmi_exit();
 352 }
 353
 354 static int __init machine_check_init(void)
 355 {
 356         ctl_set_bit(14, 25);    /* enable external damage MCH */
 357         ctl_set_bit(14, 27);    /* enable system recovery MCH */
 358         ctl_set_bit(14, 24);    /* enable warning MCH */
 359         return 0;
 360 }
 361 arch_initcall(machine_check_init);