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); 362