1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 /* 27 * When the operating system detects that it is in an invalid state, a panic 28 * is initiated in order to minimize potential damage to user data and to 29 * facilitate debugging. There are three major tasks to be performed in 30 * a system panic: recording information about the panic in memory (and thus 31 * making it part of the crash dump), synchronizing the file systems to 32 * preserve user file data, and generating the crash dump. We define the 33 * system to be in one of four states with respect to the panic code: 34 * 35 * CALM - the state of the system prior to any thread initiating a panic 36 * 37 * QUIESCE - the state of the system when the first thread to initiate 38 * a system panic records information about the cause of the panic 39 * and renders the system quiescent by stopping other processors 40 * 41 * SYNC - the state of the system when we synchronize the file systems 42 * DUMP - the state when we generate the crash dump. 43 * 44 * The transitions between these states are irreversible: once we begin 45 * panicking, we only make one attempt to perform the actions associated with 46 * each state. 47 * 48 * The panic code itself must be re-entrant because actions taken during any 49 * state may lead to another system panic. Additionally, any Solaris 50 * thread may initiate a panic at any time, and so we must have synchronization 51 * between threads which attempt to initiate a state transition simultaneously. 52 * The panic code makes use of a special locking primitive, a trigger, to 53 * perform this synchronization. A trigger is simply a word which is set 54 * atomically and can only be set once. We declare three triggers, one for 55 * each transition between the four states. When a thread enters the panic 56 * code it attempts to set each trigger; if it fails it moves on to the 57 * next trigger. A special case is the first trigger: if two threads race 58 * to perform the transition to QUIESCE, the losing thread may execute before 59 * the winner has a chance to stop its CPU. To solve this problem, we have 60 * the loser look ahead to see if any other triggers are set; if not, it 61 * presumes a panic is underway and simply spins. Unfortunately, since we 62 * are panicking, it is not possible to know this with absolute certainty. 63 * 64 * There are two common reasons for re-entering the panic code once a panic 65 * has been initiated: (1) after we debug_enter() at the end of QUIESCE, 66 * the operator may type "sync" instead of "go", and the PROM's sync callback 67 * routine will invoke panic(); (2) if the clock routine decides that sync 68 * or dump is not making progress, it will invoke panic() to force a timeout. 69 * The design assumes that a third possibility, another thread causing an 70 * unrelated panic while sync or dump is still underway, is extremely unlikely. 71 * If this situation occurs, we may end up triggering dump while sync is 72 * still in progress. This third case is considered extremely unlikely because 73 * all other CPUs are stopped and low-level interrupts have been blocked. 74 * 75 * The panic code is entered via a call directly to the vpanic() function, 76 * or its varargs wrappers panic() and cmn_err(9F). The vpanic routine 77 * is implemented in assembly language to record the current machine 78 * registers, attempt to set the trigger for the QUIESCE state, and 79 * if successful, switch stacks on to the panic_stack before calling into 80 * the common panicsys() routine. The first thread to initiate a panic 81 * is allowed to make use of the reserved panic_stack so that executing 82 * the panic code itself does not overwrite valuable data on that thread's 83 * stack *ahead* of the current stack pointer. This data will be preserved 84 * in the crash dump and may prove invaluable in determining what this 85 * thread has previously been doing. The first thread, saved in panic_thread, 86 * is also responsible for stopping the other CPUs as quickly as possible, 87 * and then setting the various panic_* variables. Most important among 88 * these is panicstr, which allows threads to subsequently bypass held 89 * locks so that we can proceed without ever blocking. We must stop the 90 * other CPUs *prior* to setting panicstr in case threads running there are 91 * currently spinning to acquire a lock; we want that state to be preserved. 92 * Every thread which initiates a panic has its T_PANIC flag set so we can 93 * identify all such threads in the crash dump. 94 * 95 * The panic_thread is also allowed to make use of the special memory buffer 96 * panicbuf, which on machines with appropriate hardware is preserved across 97 * reboots. We allow the panic_thread to store its register set and panic 98 * message in this buffer, so even if we fail to obtain a crash dump we will 99 * be able to examine the machine after reboot and determine some of the 100 * state at the time of the panic. If we do get a dump, the panic buffer 101 * data is structured so that a debugger can easily consume the information 102 * therein (see <sys/panic.h>). 103 * 104 * Each platform or architecture is required to implement the functions 105 * panic_savetrap() to record trap-specific information to panicbuf, 106 * panic_saveregs() to record a register set to panicbuf, panic_stopcpus() 107 * to halt all CPUs but the panicking CPU, panic_quiesce_hw() to perform 108 * miscellaneous platform-specific tasks *after* panicstr is set, 109 * panic_showtrap() to print trap-specific information to the console, 110 * and panic_dump_hw() to perform platform tasks prior to calling dumpsys(). 111 * 112 * A Note on Word Formation, courtesy of the Oxford Guide to English Usage: 113 * 114 * Words ending in -c interpose k before suffixes which otherwise would 115 * indicate a soft c, and thus the verb and adjective forms of 'panic' are 116 * spelled "panicked", "panicking", and "panicky" respectively. Use of 117 * the ill-conceived "panicing" and "panic'd" is discouraged. 118 */ 119 120 #include <sys/types.h> 121 #include <sys/varargs.h> 122 #include <sys/sysmacros.h> 123 #include <sys/cmn_err.h> 124 #include <sys/cpuvar.h> 125 #include <sys/thread.h> 126 #include <sys/t_lock.h> 127 #include <sys/cred.h> 128 #include <sys/systm.h> 129 #include <sys/archsystm.h> 130 #include <sys/uadmin.h> 131 #include <sys/callb.h> 132 #include <sys/vfs.h> 133 #include <sys/log.h> 134 #include <sys/disp.h> 135 #include <sys/param.h> 136 #include <sys/dumphdr.h> 137 #include <sys/ftrace.h> 138 #include <sys/reboot.h> 139 #include <sys/debug.h> 140 #include <sys/stack.h> 141 #include <sys/spl.h> 142 #include <sys/errorq.h> 143 #include <sys/panic.h> 144 #include <sys/fm/util.h> 145 146 /* 147 * Panic variables which are set once during the QUIESCE state by the 148 * first thread to initiate a panic. These are examined by post-mortem 149 * debugging tools; the inconsistent use of 'panic' versus 'panic_' in 150 * the variable naming is historical and allows legacy tools to work. 151 */ 152 #pragma align STACK_ALIGN(panic_stack) 153 char panic_stack[PANICSTKSIZE]; /* reserved stack for panic_thread */ 154 kthread_t *panic_thread; /* first thread to call panicsys() */ 155 cpu_t panic_cpu; /* cpu from first call to panicsys() */ 156 label_t panic_regs; /* setjmp label from panic_thread */ 157 struct regs *panic_reg; /* regs struct from first panicsys() */ 158 char *volatile panicstr; /* format string to first panicsys() */ 159 va_list panicargs; /* arguments to first panicsys() */ 160 clock_t panic_lbolt; /* lbolt at time of panic */ 161 int64_t panic_lbolt64; /* lbolt64 at time of panic */ 162 hrtime_t panic_hrtime; /* hrtime at time of panic */ 163 timespec_t panic_hrestime; /* hrestime at time of panic */ 164 int panic_ipl; /* ipl on panic_cpu at time of panic */ 165 ushort_t panic_schedflag; /* t_schedflag for panic_thread */ 166 cpu_t *panic_bound_cpu; /* t_bound_cpu for panic_thread */ 167 char panic_preempt; /* t_preempt for panic_thread */ 168 169 /* 170 * Panic variables which can be set via /etc/system or patched while 171 * the system is in operation. Again, the stupid names are historic. 172 */ 173 char *panic_bootstr = NULL; /* mdboot string to use after panic */ 174 int panic_bootfcn = AD_BOOT; /* mdboot function to use after panic */ 175 int halt_on_panic = 0; /* halt after dump instead of reboot? */ 176 int nopanicdebug = 0; /* reboot instead of call debugger? */ 177 int in_sync = 0; /* skip vfs_syncall() and just dump? */ 178 179 /* 180 * The do_polled_io flag is set by the panic code to inform the SCSI subsystem 181 * to use polled mode instead of interrupt-driven i/o. 182 */ 183 int do_polled_io = 0; 184 185 /* 186 * The panic_forced flag is set by the uadmin A_DUMP code to inform the 187 * panic subsystem that it should not attempt an initial debug_enter. 188 */ 189 int panic_forced = 0; 190 191 /* 192 * Triggers for panic state transitions: 193 */ 194 int panic_quiesce; /* trigger for CALM -> QUIESCE */ 195 int panic_sync; /* trigger for QUIESCE -> SYNC */ 196 int panic_dump; /* trigger for SYNC -> DUMP */ 197 198 /* 199 * Variable signifying quiesce(9E) is in progress. 200 */ 201 volatile int quiesce_active = 0; 202 203 void 204 panicsys(const char *format, va_list alist, struct regs *rp, int on_panic_stack) 205 { 206 int s = spl8(); 207 kthread_t *t = curthread; 208 cpu_t *cp = CPU; 209 210 caddr_t intr_stack = NULL; 211 uint_t intr_actv; 212 213 ushort_t schedflag = t->t_schedflag; 214 cpu_t *bound_cpu = t->t_bound_cpu; 215 char preempt = t->t_preempt; 216 217 (void) setjmp(&t->t_pcb); 218 t->t_flag |= T_PANIC; 219 220 t->t_schedflag |= TS_DONT_SWAP; 221 t->t_bound_cpu = cp; 222 t->t_preempt++; 223 224 panic_enter_hw(s); 225 226 /* 227 * If we're on the interrupt stack and an interrupt thread is available 228 * in this CPU's pool, preserve the interrupt stack by detaching an 229 * interrupt thread and making its stack the intr_stack. 230 */ 231 if (CPU_ON_INTR(cp) && cp->cpu_intr_thread != NULL) { 232 kthread_t *it = cp->cpu_intr_thread; 233 234 intr_stack = cp->cpu_intr_stack; 235 intr_actv = cp->cpu_intr_actv; 236 237 cp->cpu_intr_stack = thread_stk_init(it->t_stk); 238 cp->cpu_intr_thread = it->t_link; 239 240 /* 241 * Clear only the high level bits of cpu_intr_actv. 242 * We want to indicate that high-level interrupts are 243 * not active without destroying the low-level interrupt 244 * information stored there. 245 */ 246 cp->cpu_intr_actv &= ((1 << (LOCK_LEVEL + 1)) - 1); 247 } 248 249 /* 250 * Record one-time panic information and quiesce the other CPUs. 251 * Then print out the panic message and stack trace. 252 */ 253 if (on_panic_stack) { 254 panic_data_t *pdp = (panic_data_t *)panicbuf; 255 256 pdp->pd_version = PANICBUFVERS; 257 pdp->pd_msgoff = sizeof (panic_data_t) - sizeof (panic_nv_t); 258 259 if (t->t_panic_trap != NULL) 260 panic_savetrap(pdp, t->t_panic_trap); 261 else 262 panic_saveregs(pdp, rp); 263 264 (void) vsnprintf(&panicbuf[pdp->pd_msgoff], 265 PANICBUFSIZE - pdp->pd_msgoff, format, alist); 266 267 /* 268 * Call into the platform code to stop the other CPUs. 269 * We currently have all interrupts blocked, and expect that 270 * the platform code will lower ipl only as far as needed to 271 * perform cross-calls, and will acquire as *few* locks as is 272 * possible -- panicstr is not set so we can still deadlock. 273 */ 274 panic_stopcpus(cp, t, s); 275 276 panicstr = (char *)format; 277 va_copy(panicargs, alist); 278 panic_lbolt = lbolt; 279 panic_lbolt64 = lbolt64; 280 panic_hrestime = hrestime; 281 panic_hrtime = gethrtime_waitfree(); 282 panic_thread = t; 283 panic_regs = t->t_pcb; 284 panic_reg = rp; 285 panic_cpu = *cp; 286 panic_ipl = spltoipl(s); 287 panic_schedflag = schedflag; 288 panic_bound_cpu = bound_cpu; 289 panic_preempt = preempt; 290 291 if (intr_stack != NULL) { 292 panic_cpu.cpu_intr_stack = intr_stack; 293 panic_cpu.cpu_intr_actv = intr_actv; 294 } 295 296 /* 297 * Lower ipl to 10 to keep clock() from running, but allow 298 * keyboard interrupts to enter the debugger. These callbacks 299 * are executed with panicstr set so they can bypass locks. 300 */ 301 splx(ipltospl(CLOCK_LEVEL)); 302 panic_quiesce_hw(pdp); 303 (void) FTRACE_STOP(); 304 (void) callb_execute_class(CB_CL_PANIC, NULL); 305 306 if (log_intrq != NULL) 307 log_flushq(log_intrq); 308 309 /* 310 * If log_consq has been initialized and syslogd has started, 311 * print any messages in log_consq that haven't been consumed. 312 */ 313 if (log_consq != NULL && log_consq != log_backlogq) 314 log_printq(log_consq); 315 316 fm_banner(); 317 318 #if defined(__x86) 319 /* 320 * A hypervisor panic originates outside of Solaris, so we 321 * don't want to prepend the panic message with misleading 322 * pointers from within Solaris. 323 */ 324 if (!IN_XPV_PANIC()) 325 #endif 326 printf("\n\rpanic[cpu%d]/thread=%p: ", cp->cpu_id, 327 (void *)t); 328 vprintf(format, alist); 329 printf("\n\n"); 330 331 if (t->t_panic_trap != NULL) { 332 panic_showtrap(t->t_panic_trap); 333 printf("\n"); 334 } 335 336 traceregs(rp); 337 printf("\n"); 338 339 if (((boothowto & RB_DEBUG) || obpdebug) && 340 !nopanicdebug && !panic_forced) { 341 if (dumpvp != NULL) { 342 debug_enter("panic: entering debugger " 343 "(continue to save dump)"); 344 } else { 345 debug_enter("panic: entering debugger " 346 "(no dump device, continue to reboot)"); 347 } 348 } 349 350 } else if (panic_dump != 0 || panic_sync != 0 || panicstr != NULL) { 351 printf("\n\rpanic[cpu%d]/thread=%p: ", cp->cpu_id, (void *)t); 352 vprintf(format, alist); 353 printf("\n"); 354 } else 355 goto spin; 356 357 /* 358 * Prior to performing sync or dump, we make sure that do_polled_io is 359 * set, but we'll leave ipl at 10; deadman(), a CY_HIGH_LEVEL cyclic, 360 * will re-enter panic if we are not making progress with sync or dump. 361 */ 362 363 /* 364 * Sync the filesystems. Reset t_cred if not set because much of 365 * the filesystem code depends on CRED() being valid. 366 */ 367 if (!in_sync && panic_trigger(&panic_sync)) { 368 if (t->t_cred == NULL) 369 t->t_cred = kcred; 370 splx(ipltospl(CLOCK_LEVEL)); 371 do_polled_io = 1; 372 vfs_syncall(); 373 } 374 375 /* 376 * Take the crash dump. If the dump trigger is already set, try to 377 * enter the debugger again before rebooting the system. 378 */ 379 if (panic_trigger(&panic_dump)) { 380 panic_dump_hw(s); 381 splx(ipltospl(CLOCK_LEVEL)); 382 errorq_panic(); 383 do_polled_io = 1; 384 dumpsys(); 385 } else if (((boothowto & RB_DEBUG) || obpdebug) && !nopanicdebug) { 386 debug_enter("panic: entering debugger (continue to reboot)"); 387 } else 388 printf("dump aborted: please record the above information!\n"); 389 390 if (halt_on_panic) 391 mdboot(A_REBOOT, AD_HALT, NULL, B_FALSE); 392 else 393 mdboot(A_REBOOT, panic_bootfcn, panic_bootstr, B_FALSE); 394 spin: 395 /* 396 * Restore ipl to at most CLOCK_LEVEL so we don't end up spinning 397 * and unable to jump into the debugger. 398 */ 399 splx(MIN(s, ipltospl(CLOCK_LEVEL))); 400 for (;;) 401 ; 402 } 403 404 void 405 panic(const char *format, ...) 406 { 407 va_list alist; 408 409 va_start(alist, format); 410 vpanic(format, alist); 411 va_end(alist); 412 } 413