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/stp.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 stp_queue : 1;
  31         unsigned long mcck_code;
  32 };
  33
  34 static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
  35
  36 static void s390_handle_damage(void)
  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.stp_queue)
  85                 stp_queue_work();
  86         if (mcck.kill_task) {
  87                 local_irq_enable();
  88                 printk(KERN_EMERG "mcck: Terminating task because of machine "
  89                        "malfunction (code 0x%016lx).\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_validate_registers(union 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         fpt_save_area = &S390_lowcore.floating_pt_save_area;
 125         fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
 126         if (!mci.fc) {
 127                 /*
 128                  * Floating point control register can't be restored.
 129                  * Task will be terminated.
 130                  */
 131                 asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
 132                 kill_task = 1;
 133         } else
 134                 asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
 135
 136         if (!MACHINE_HAS_VX) {
 137                 /* Validate floating point registers */
 138                 asm volatile(
 139                         "       ld      0,0(%0)\n"
 140                         "       ld      1,8(%0)\n"
 141                         "       ld      2,16(%0)\n"
 142                         "       ld      3,24(%0)\n"
 143                         "       ld      4,32(%0)\n"
 144                         "       ld      5,40(%0)\n"
 145                         "       ld      6,48(%0)\n"
 146                         "       ld      7,56(%0)\n"
 147                         "       ld      8,64(%0)\n"
 148                         "       ld      9,72(%0)\n"
 149                         "       ld      10,80(%0)\n"
 150                         "       ld      11,88(%0)\n"
 151                         "       ld      12,96(%0)\n"
 152                         "       ld      13,104(%0)\n"
 153                         "       ld      14,112(%0)\n"
 154                         "       ld      15,120(%0)\n"
 155                         : : "a" (fpt_save_area));
 156         } else {
 157                 /* Validate vector registers */
 158                 union ctlreg0 cr0;
 159
 160                 if (!mci.vr) {
 161                         /*
 162                          * Vector registers can't be restored and therefore
 163                          * the process needs to be terminated.
 164                          */
 165                         kill_task = 1;
 166                 }
 167                 cr0.val = S390_lowcore.cregs_save_area[0];
 168                 cr0.afp = cr0.vx = 1;
 169                 __ctl_load(cr0.val, 0, 0);
 170                 asm volatile(
 171                         "       la      1,%0\n"
 172                         "       .word   0xe70f,0x1000,0x0036\n" /* vlm 0,15,0(1) */
 173                         "       .word   0xe70f,0x1100,0x0c36\n" /* vlm 16,31,256(1) */
 174                         : : "Q" (*(struct vx_array *)
 175                                  &S390_lowcore.vector_save_area) : "1");
 176                 __ctl_load(S390_lowcore.cregs_save_area[0], 0, 0);
 177         }
 178         /* Validate access registers */
 179         asm volatile(
 180                 "       lam     0,15,0(%0)"
 181                 : : "a" (&S390_lowcore.access_regs_save_area));
 182         if (!mci.ar) {
 183                 /*
 184                  * Access registers have unknown contents.
 185                  * Terminating task.
 186                  */
 187                 kill_task = 1;
 188         }
 189         /* Validate control registers */
 190         if (!mci.cr) {
 191                 /*
 192                  * Control registers have unknown contents.
 193                  * Can't recover and therefore stopping machine.
 194                  */
 195                 s390_handle_damage();
 196         } else {
 197                 asm volatile(
 198                         "       lctlg   0,15,0(%0)"
 199                         : : "a" (&S390_lowcore.cregs_save_area));
 200         }
 201         /*
 202          * We don't even try to validate the TOD register, since we simply
 203          * can't write something sensible into that register.
 204          */
 205         /*
 206          * See if we can validate the TOD programmable register with its
 207          * old contents (should be zero) otherwise set it to zero.
 208          */
 209         if (!mci.pr)
 210                 asm volatile(
 211                         "       sr      0,0\n"
 212                         "       sckpf"
 213                         : : : "0", "cc");
 214         else
 215                 asm volatile(
 216                         "       l       0,0(%0)\n"
 217                         "       sckpf"
 218                         : : "a" (&S390_lowcore.tod_progreg_save_area)
 219                         : "0", "cc");
 220         /* Validate clock comparator register */
 221         set_clock_comparator(S390_lowcore.clock_comparator);
 222         /* Check if old PSW is valid */
 223         if (!mci.wp)
 224                 /*
 225                  * Can't tell if we come from user or kernel mode
 226                  * -> stopping machine.
 227                  */
 228                 s390_handle_damage();
 229
 230         if (!mci.ms || !mci.pm || !mci.ia)
 231                 kill_task = 1;
 232
 233         return kill_task;
 234 }
 235
 236 #define MAX_IPD_COUNT   29
 237 #define MAX_IPD_TIME    (5 * 60 * USEC_PER_SEC) /* 5 minutes */
 238
 239 #define ED_STP_ISLAND   6       /* External damage STP island check */
 240 #define ED_STP_SYNC     7       /* External damage STP sync check */
 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         union mci mci;
 253         int umode;
 254
 255         nmi_enter();
 256         inc_irq_stat(NMI_NMI);
 257         mci.val = 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();
 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 = mci.val;
 275
 276                         if (((t_mcic & z_mcic) != 0) ||
 277                             ((t_mcic & o_mcic) != o_mcic)) {
 278                                 s390_handle_damage();
 279                         }
 280
 281                         /*
 282                          * Nullifying exigent condition, therefore we might
 283                          * retry this instruction.
 284                          */
 285                         spin_lock(&ipd_lock);
 286                         tmp = get_tod_clock();
 287                         if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
 288                                 ipd_count++;
 289                         else
 290                                 ipd_count = 1;
 291                         last_ipd = tmp;
 292                         if (ipd_count == MAX_IPD_COUNT)
 293                                 s390_handle_damage();
 294                         spin_unlock(&ipd_lock);
 295                 } else {
 296                         /* Processing damage -> stopping machine */
 297                         s390_handle_damage();
 298                 }
 299         }
 300         if (s390_validate_registers(mci)) {
 301                 if (umode) {
 302                         /*
 303                          * Couldn't restore all register contents while in
 304                          * user mode -> mark task for termination.
 305                          */
 306                         mcck->kill_task = 1;
 307                         mcck->mcck_code = mci.val;
 308                         set_cpu_flag(CIF_MCCK_PENDING);
 309                 } else {
 310                         /*
 311                          * Couldn't restore all register contents while in
 312                          * kernel mode -> stopping machine.
 313                          */
 314                         s390_handle_damage();
 315                 }
 316         }
 317         if (mci.cd) {
 318                 /* Timing facility damage */
 319                 s390_handle_damage();
 320         }
 321         if (mci.ed && mci.ec) {
 322                 /* External damage */
 323                 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
 324                         mcck->stp_queue |= stp_sync_check();
 325                 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
 326                         mcck->stp_queue |= stp_island_check();
 327                 if (mcck->stp_queue)
 328                         set_cpu_flag(CIF_MCCK_PENDING);
 329         }
 330         if (mci.se)
 331                 /* Storage error uncorrected */
 332                 s390_handle_damage();
 333         if (mci.ke)
 334                 /* Storage key-error uncorrected */
 335                 s390_handle_damage();
 336         if (mci.ds && mci.fa)
 337                 /* Storage degradation */
 338                 s390_handle_damage();
 339         if (mci.cp) {
 340                 /* Channel report word pending */
 341                 mcck->channel_report = 1;
 342                 set_cpu_flag(CIF_MCCK_PENDING);
 343         }
 344         if (mci.w) {
 345                 /* Warning pending */
 346                 mcck->warning = 1;
 347                 set_cpu_flag(CIF_MCCK_PENDING);
 348         }
 349         nmi_exit();
 350 }
 351
 352 static int __init machine_check_init(void)
 353 {
 354         ctl_set_bit(14, 25);    /* enable external damage MCH */
 355         ctl_set_bit(14, 27);    /* enable system recovery MCH */
 356         ctl_set_bit(14, 24);    /* enable warning MCH */
 357         return 0;
 358 }
 359 early_initcall(machine_check_init);