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 <linux/sched/signal.h>
  18
  19 #include <linux/export.h>
  20 #include <asm/lowcore.h>
  21 #include <asm/smp.h>
  22 #include <asm/stp.h>
  23 #include <asm/cputime.h>
  24 #include <asm/nmi.h>
  25 #include <asm/crw.h>
  26 #include <asm/switch_to.h>
  27 #include <asm/ctl_reg.h>
  28
  29 struct mcck_struct {
  30         unsigned int kill_task : 1;
  31         unsigned int channel_report : 1;
  32         unsigned int warning : 1;
  33         unsigned int stp_queue : 1;
  34         unsigned long mcck_code;
  35 };
  36
  37 static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
  38
  39 static void s390_handle_damage(void)
  40 {
  41         smp_send_stop();
  42         disabled_wait((unsigned long) __builtin_return_address(0));
  43         while (1);
  44 }
  45
  46 /*
  47  * Main machine check handler function. Will be called with interrupts enabled
  48  * or disabled and machine checks enabled or disabled.
  49  */
  50 void s390_handle_mcck(void)
  51 {
  52         unsigned long flags;
  53         struct mcck_struct mcck;
  54
  55         /*
  56          * Disable machine checks and get the current state of accumulated
  57          * machine checks. Afterwards delete the old state and enable machine
  58          * checks again.
  59          */
  60         local_irq_save(flags);
  61         local_mcck_disable();
  62         mcck = *this_cpu_ptr(&cpu_mcck);
  63         memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
  64         clear_cpu_flag(CIF_MCCK_PENDING);
  65         local_mcck_enable();
  66         local_irq_restore(flags);
  67
  68         if (mcck.channel_report)
  69                 crw_handle_channel_report();
  70         /*
  71          * A warning may remain for a prolonged period on the bare iron.
  72          * (actually until the machine is powered off, or the problem is gone)
  73          * So we just stop listening for the WARNING MCH and avoid continuously
  74          * being interrupted.  One caveat is however, that we must do this per
  75          * processor and cannot use the smp version of ctl_clear_bit().
  76          * On VM we only get one interrupt per virtally presented machinecheck.
  77          * Though one suffices, we may get one interrupt per (virtual) cpu.
  78          */
  79         if (mcck.warning) {     /* WARNING pending ? */
  80                 static int mchchk_wng_posted = 0;
  81
  82                 /* Use single cpu clear, as we cannot handle smp here. */
  83                 __ctl_clear_bit(14, 24);        /* Disable WARNING MCH */
  84                 if (xchg(&mchchk_wng_posted, 1) == 0)
  85                         kill_cad_pid(SIGPWR, 1);
  86         }
  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, int umode)
 105 {
 106         int kill_task;
 107         u64 zero;
 108         void *fpt_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. Stop system or terminate process.
 117                  */
 118                 if (!umode)
 119                         s390_handle_damage();
 120                 kill_task = 1;
 121         }
 122         /* Validate control registers */
 123         if (!mci.cr) {
 124                 /*
 125                  * Control registers have unknown contents.
 126                  * Can't recover and therefore stopping machine.
 127                  */
 128                 s390_handle_damage();
 129         } else {
 130                 asm volatile(
 131                         "       lctlg   0,15,0(%0)\n"
 132                         "       ptlb\n"
 133                         : : "a" (&S390_lowcore.cregs_save_area) : "memory");
 134         }
 135         if (!mci.fp) {
 136                 /*
 137                  * Floating point registers can't be restored. If the
 138                  * kernel currently uses floating point registers the
 139                  * system is stopped. If the process has its floating
 140                  * pointer registers loaded it is terminated.
 141                  * Otherwise just revalidate the registers.
 142                  */
 143                 if (S390_lowcore.fpu_flags & KERNEL_VXR_V0V7)
 144                         s390_handle_damage();
 145                 if (!test_cpu_flag(CIF_FPU))
 146                         kill_task = 1;
 147         }
 148         fpt_save_area = &S390_lowcore.floating_pt_save_area;
 149         if (!mci.fc) {
 150                 /*
 151                  * Floating point control register can't be restored.
 152                  * If the kernel currently uses the floating pointer
 153                  * registers and needs the FPC register the system is
 154                  * stopped. If the process has its floating pointer
 155                  * registers loaded it is terminated. Otherwiese the
 156                  * FPC is just revalidated.
 157                  */
 158                 if (S390_lowcore.fpu_flags & KERNEL_FPC)
 159                         s390_handle_damage();
 160                 asm volatile("lfpc %0" : : "Q" (zero));
 161                 if (!test_cpu_flag(CIF_FPU))
 162                         kill_task = 1;
 163         } else {
 164                 asm volatile("lfpc %0"
 165                              : : "Q" (S390_lowcore.fpt_creg_save_area));
 166         }
 167
 168         if (!MACHINE_HAS_VX) {
 169                 /* Validate floating point registers */
 170                 asm volatile(
 171                         "       ld      0,0(%0)\n"
 172                         "       ld      1,8(%0)\n"
 173                         "       ld      2,16(%0)\n"
 174                         "       ld      3,24(%0)\n"
 175                         "       ld      4,32(%0)\n"
 176                         "       ld      5,40(%0)\n"
 177                         "       ld      6,48(%0)\n"
 178                         "       ld      7,56(%0)\n"
 179                         "       ld      8,64(%0)\n"
 180                         "       ld      9,72(%0)\n"
 181                         "       ld      10,80(%0)\n"
 182                         "       ld      11,88(%0)\n"
 183                         "       ld      12,96(%0)\n"
 184                         "       ld      13,104(%0)\n"
 185                         "       ld      14,112(%0)\n"
 186                         "       ld      15,120(%0)\n"
 187                         : : "a" (fpt_save_area) : "memory");
 188         } else {
 189                 /* Validate vector registers */
 190                 union ctlreg0 cr0;
 191
 192                 if (!mci.vr) {
 193                         /*
 194                          * Vector registers can't be restored. If the kernel
 195                          * currently uses vector registers the system is
 196                          * stopped. If the process has its vector registers
 197                          * loaded it is terminated. Otherwise just revalidate
 198                          * the registers.
 199                          */
 200                         if (S390_lowcore.fpu_flags & KERNEL_VXR)
 201                                 s390_handle_damage();
 202                         if (!test_cpu_flag(CIF_FPU))
 203                                 kill_task = 1;
 204                 }
 205                 cr0.val = S390_lowcore.cregs_save_area[0];
 206                 cr0.afp = cr0.vx = 1;
 207                 __ctl_load(cr0.val, 0, 0);
 208                 asm volatile(
 209                         "       la      1,%0\n"
 210                         "       .word   0xe70f,0x1000,0x0036\n" /* vlm 0,15,0(1) */
 211                         "       .word   0xe70f,0x1100,0x0c36\n" /* vlm 16,31,256(1) */
 212                         : : "Q" (*(struct vx_array *)
 213                                  &S390_lowcore.vector_save_area) : "1");
 214                 __ctl_load(S390_lowcore.cregs_save_area[0], 0, 0);
 215         }
 216         /* Validate access registers */
 217         asm volatile(
 218                 "       lam     0,15,0(%0)"
 219                 : : "a" (&S390_lowcore.access_regs_save_area));
 220         if (!mci.ar) {
 221                 /*
 222                  * Access registers have unknown contents.
 223                  * Terminating task.
 224                  */
 225                 kill_task = 1;
 226         }
 227         /*
 228          * We don't even try to validate the TOD register, since we simply
 229          * can't write something sensible into that register.
 230          */
 231         /*
 232          * See if we can validate the TOD programmable register with its
 233          * old contents (should be zero) otherwise set it to zero.
 234          */
 235         if (!mci.pr)
 236                 asm volatile(
 237                         "       sr      0,0\n"
 238                         "       sckpf"
 239                         : : : "0", "cc");
 240         else
 241                 asm volatile(
 242                         "       l       0,%0\n"
 243                         "       sckpf"
 244                         : : "Q" (S390_lowcore.tod_progreg_save_area)
 245                         : "0", "cc");
 246         /* Validate clock comparator register */
 247         set_clock_comparator(S390_lowcore.clock_comparator);
 248         /* Check if old PSW is valid */
 249         if (!mci.wp)
 250                 /*
 251                  * Can't tell if we come from user or kernel mode
 252                  * -> stopping machine.
 253                  */
 254                 s390_handle_damage();
 255
 256         if (!mci.ms || !mci.pm || !mci.ia)
 257                 kill_task = 1;
 258
 259         return kill_task;
 260 }
 261
 262 #define MAX_IPD_COUNT   29
 263 #define MAX_IPD_TIME    (5 * 60 * USEC_PER_SEC) /* 5 minutes */
 264
 265 #define ED_STP_ISLAND   6       /* External damage STP island check */
 266 #define ED_STP_SYNC     7       /* External damage STP sync check */
 267
 268 /*
 269  * machine check handler.
 270  */
 271 void notrace s390_do_machine_check(struct pt_regs *regs)
 272 {
 273         static int ipd_count;
 274         static DEFINE_SPINLOCK(ipd_lock);
 275         static unsigned long long last_ipd;
 276         struct mcck_struct *mcck;
 277         unsigned long long tmp;
 278         union mci mci;
 279
 280         nmi_enter();
 281         inc_irq_stat(NMI_NMI);
 282         mci.val = S390_lowcore.mcck_interruption_code;
 283         mcck = this_cpu_ptr(&cpu_mcck);
 284
 285         if (mci.sd) {
 286                 /* System damage -> stopping machine */
 287                 s390_handle_damage();
 288         }
 289         if (mci.pd) {
 290                 if (mci.b) {
 291                         /* Processing backup -> verify if we can survive this */
 292                         u64 z_mcic, o_mcic, t_mcic;
 293                         z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
 294                         o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
 295                                   1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
 296                                   1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
 297                                   1ULL<<16);
 298                         t_mcic = mci.val;
 299
 300                         if (((t_mcic & z_mcic) != 0) ||
 301                             ((t_mcic & o_mcic) != o_mcic)) {
 302                                 s390_handle_damage();
 303                         }
 304
 305                         /*
 306                          * Nullifying exigent condition, therefore we might
 307                          * retry this instruction.
 308                          */
 309                         spin_lock(&ipd_lock);
 310                         tmp = get_tod_clock();
 311                         if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
 312                                 ipd_count++;
 313                         else
 314                                 ipd_count = 1;
 315                         last_ipd = tmp;
 316                         if (ipd_count == MAX_IPD_COUNT)
 317                                 s390_handle_damage();
 318                         spin_unlock(&ipd_lock);
 319                 } else {
 320                         /* Processing damage -> stopping machine */
 321                         s390_handle_damage();
 322                 }
 323         }
 324         if (s390_validate_registers(mci, user_mode(regs))) {
 325                 /*
 326                  * Couldn't restore all register contents for the
 327                  * user space process -> mark task for termination.
 328                  */
 329                 mcck->kill_task = 1;
 330                 mcck->mcck_code = mci.val;
 331                 set_cpu_flag(CIF_MCCK_PENDING);
 332         }
 333         if (mci.cd) {
 334                 /* Timing facility damage */
 335                 s390_handle_damage();
 336         }
 337         if (mci.ed && mci.ec) {
 338                 /* External damage */
 339                 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
 340                         mcck->stp_queue |= stp_sync_check();
 341                 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
 342                         mcck->stp_queue |= stp_island_check();
 343                 if (mcck->stp_queue)
 344                         set_cpu_flag(CIF_MCCK_PENDING);
 345         }
 346         if (mci.se)
 347                 /* Storage error uncorrected */
 348                 s390_handle_damage();
 349         if (mci.ke)
 350                 /* Storage key-error uncorrected */
 351                 s390_handle_damage();
 352         if (mci.ds && mci.fa)
 353                 /* Storage degradation */
 354                 s390_handle_damage();
 355         if (mci.cp) {
 356                 /* Channel report word pending */
 357                 mcck->channel_report = 1;
 358                 set_cpu_flag(CIF_MCCK_PENDING);
 359         }
 360         if (mci.w) {
 361                 /* Warning pending */
 362                 mcck->warning = 1;
 363                 set_cpu_flag(CIF_MCCK_PENDING);
 364         }
 365         nmi_exit();
 366 }
 367
 368 static int __init machine_check_init(void)
 369 {
 370         ctl_set_bit(14, 25);    /* enable external damage MCH */
 371         ctl_set_bit(14, 27);    /* enable system recovery MCH */
 372         ctl_set_bit(14, 24);    /* enable warning MCH */
 373         return 0;
 374 }
 375 early_initcall(machine_check_init);