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, int umode)
 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. Stop system or terminate process.
 114                  */
 115                 if (!umode)
 116                         s390_handle_damage();
 117                 kill_task = 1;
 118         }
 119         if (!mci.fp) {
 120                 /*
 121                  * Floating point registers can't be restored. If the
 122                  * kernel currently uses floating point registers the
 123                  * system is stopped. If the process has its floating
 124                  * pointer registers loaded it is terminated.
 125                  * Otherwise just revalidate the registers.
 126                  */
 127                 if (S390_lowcore.fpu_flags & KERNEL_VXR_V0V7)
 128                         s390_handle_damage();
 129                 if (!test_cpu_flag(CIF_FPU))
 130                         kill_task = 1;
 131         }
 132         fpt_save_area = &S390_lowcore.floating_pt_save_area;
 133         fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
 134         if (!mci.fc) {
 135                 /*
 136                  * Floating point control register can't be restored.
 137                  * If the kernel currently uses the floating pointer
 138                  * registers and needs the FPC register the system is
 139                  * stopped. If the process has its floating pointer
 140                  * registers loaded it is terminated. Otherwiese the
 141                  * FPC is just revalidated.
 142                  */
 143                 if (S390_lowcore.fpu_flags & KERNEL_FPC)
 144                         s390_handle_damage();
 145                 asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
 146                 if (!test_cpu_flag(CIF_FPU))
 147                         kill_task = 1;
 148         } else
 149                 asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
 150
 151         if (!MACHINE_HAS_VX) {
 152                 /* Validate floating point registers */
 153                 asm volatile(
 154                         "       ld      0,0(%0)\n"
 155                         "       ld      1,8(%0)\n"
 156                         "       ld      2,16(%0)\n"
 157                         "       ld      3,24(%0)\n"
 158                         "       ld      4,32(%0)\n"
 159                         "       ld      5,40(%0)\n"
 160                         "       ld      6,48(%0)\n"
 161                         "       ld      7,56(%0)\n"
 162                         "       ld      8,64(%0)\n"
 163                         "       ld      9,72(%0)\n"
 164                         "       ld      10,80(%0)\n"
 165                         "       ld      11,88(%0)\n"
 166                         "       ld      12,96(%0)\n"
 167                         "       ld      13,104(%0)\n"
 168                         "       ld      14,112(%0)\n"
 169                         "       ld      15,120(%0)\n"
 170                         : : "a" (fpt_save_area));
 171         } else {
 172                 /* Validate vector registers */
 173                 union ctlreg0 cr0;
 174
 175                 if (!mci.vr) {
 176                         /*
 177                          * Vector registers can't be restored. If the kernel
 178                          * currently uses vector registers the system is
 179                          * stopped. If the process has its vector registers
 180                          * loaded it is terminated. Otherwise just revalidate
 181                          * the registers.
 182                          */
 183                         if (S390_lowcore.fpu_flags & KERNEL_VXR)
 184                                 s390_handle_damage();
 185                         if (!test_cpu_flag(CIF_FPU))
 186                                 kill_task = 1;
 187                 }
 188                 cr0.val = S390_lowcore.cregs_save_area[0];
 189                 cr0.afp = cr0.vx = 1;
 190                 __ctl_load(cr0.val, 0, 0);
 191                 asm volatile(
 192                         "       la      1,%0\n"
 193                         "       .word   0xe70f,0x1000,0x0036\n" /* vlm 0,15,0(1) */
 194                         "       .word   0xe70f,0x1100,0x0c36\n" /* vlm 16,31,256(1) */
 195                         : : "Q" (*(struct vx_array *)
 196                                  &S390_lowcore.vector_save_area) : "1");
 197                 __ctl_load(S390_lowcore.cregs_save_area[0], 0, 0);
 198         }
 199         /* Validate access registers */
 200         asm volatile(
 201                 "       lam     0,15,0(%0)"
 202                 : : "a" (&S390_lowcore.access_regs_save_area));
 203         if (!mci.ar) {
 204                 /*
 205                  * Access registers have unknown contents.
 206                  * Terminating task.
 207                  */
 208                 kill_task = 1;
 209         }
 210         /* Validate control registers */
 211         if (!mci.cr) {
 212                 /*
 213                  * Control registers have unknown contents.
 214                  * Can't recover and therefore stopping machine.
 215                  */
 216                 s390_handle_damage();
 217         } else {
 218                 asm volatile(
 219                         "       lctlg   0,15,0(%0)"
 220                         : : "a" (&S390_lowcore.cregs_save_area));
 221         }
 222         /*
 223          * We don't even try to validate the TOD register, since we simply
 224          * can't write something sensible into that register.
 225          */
 226         /*
 227          * See if we can validate the TOD programmable register with its
 228          * old contents (should be zero) otherwise set it to zero.
 229          */
 230         if (!mci.pr)
 231                 asm volatile(
 232                         "       sr      0,0\n"
 233                         "       sckpf"
 234                         : : : "0", "cc");
 235         else
 236                 asm volatile(
 237                         "       l       0,0(%0)\n"
 238                         "       sckpf"
 239                         : : "a" (&S390_lowcore.tod_progreg_save_area)
 240                         : "0", "cc");
 241         /* Validate clock comparator register */
 242         set_clock_comparator(S390_lowcore.clock_comparator);
 243         /* Check if old PSW is valid */
 244         if (!mci.wp)
 245                 /*
 246                  * Can't tell if we come from user or kernel mode
 247                  * -> stopping machine.
 248                  */
 249                 s390_handle_damage();
 250
 251         if (!mci.ms || !mci.pm || !mci.ia)
 252                 kill_task = 1;
 253
 254         return kill_task;
 255 }
 256
 257 #define MAX_IPD_COUNT   29
 258 #define MAX_IPD_TIME    (5 * 60 * USEC_PER_SEC) /* 5 minutes */
 259
 260 #define ED_STP_ISLAND   6       /* External damage STP island check */
 261 #define ED_STP_SYNC     7       /* External damage STP sync check */
 262
 263 /*
 264  * machine check handler.
 265  */
 266 void notrace s390_do_machine_check(struct pt_regs *regs)
 267 {
 268         static int ipd_count;
 269         static DEFINE_SPINLOCK(ipd_lock);
 270         static unsigned long long last_ipd;
 271         struct mcck_struct *mcck;
 272         unsigned long long tmp;
 273         union mci mci;
 274
 275         nmi_enter();
 276         inc_irq_stat(NMI_NMI);
 277         mci.val = S390_lowcore.mcck_interruption_code;
 278         mcck = this_cpu_ptr(&cpu_mcck);
 279
 280         if (mci.sd) {
 281                 /* System damage -> stopping machine */
 282                 s390_handle_damage();
 283         }
 284         if (mci.pd) {
 285                 if (mci.b) {
 286                         /* Processing backup -> verify if we can survive this */
 287                         u64 z_mcic, o_mcic, t_mcic;
 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                         t_mcic = mci.val;
 294
 295                         if (((t_mcic & z_mcic) != 0) ||
 296                             ((t_mcic & o_mcic) != o_mcic)) {
 297                                 s390_handle_damage();
 298                         }
 299
 300                         /*
 301                          * Nullifying exigent condition, therefore we might
 302                          * retry this instruction.
 303                          */
 304                         spin_lock(&ipd_lock);
 305                         tmp = get_tod_clock();
 306                         if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
 307                                 ipd_count++;
 308                         else
 309                                 ipd_count = 1;
 310                         last_ipd = tmp;
 311                         if (ipd_count == MAX_IPD_COUNT)
 312                                 s390_handle_damage();
 313                         spin_unlock(&ipd_lock);
 314                 } else {
 315                         /* Processing damage -> stopping machine */
 316                         s390_handle_damage();
 317                 }
 318         }
 319         if (s390_validate_registers(mci, user_mode(regs))) {
 320                 /*
 321                  * Couldn't restore all register contents for the
 322                  * user space process -> mark task for termination.
 323                  */
 324                 mcck->kill_task = 1;
 325                 mcck->mcck_code = mci.val;
 326                 set_cpu_flag(CIF_MCCK_PENDING);
 327         }
 328         if (mci.cd) {
 329                 /* Timing facility damage */
 330                 s390_handle_damage();
 331         }
 332         if (mci.ed && mci.ec) {
 333                 /* External damage */
 334                 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
 335                         mcck->stp_queue |= stp_sync_check();
 336                 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
 337                         mcck->stp_queue |= stp_island_check();
 338                 if (mcck->stp_queue)
 339                         set_cpu_flag(CIF_MCCK_PENDING);
 340         }
 341         if (mci.se)
 342                 /* Storage error uncorrected */
 343                 s390_handle_damage();
 344         if (mci.ke)
 345                 /* Storage key-error uncorrected */
 346                 s390_handle_damage();
 347         if (mci.ds && mci.fa)
 348                 /* Storage degradation */
 349                 s390_handle_damage();
 350         if (mci.cp) {
 351                 /* Channel report word pending */
 352                 mcck->channel_report = 1;
 353                 set_cpu_flag(CIF_MCCK_PENDING);
 354         }
 355         if (mci.w) {
 356                 /* Warning pending */
 357                 mcck->warning = 1;
 358                 set_cpu_flag(CIF_MCCK_PENDING);
 359         }
 360         nmi_exit();
 361 }
 362
 363 static int __init machine_check_init(void)
 364 {
 365         ctl_set_bit(14, 25);    /* enable external damage MCH */
 366         ctl_set_bit(14, 27);    /* enable system recovery MCH */
 367         ctl_set_bit(14, 24);    /* enable warning MCH */
 368         return 0;
 369 }
 370 early_initcall(machine_check_init);