1 /* 2 * arch/xtensa/kernel/traps.c 3 * 4 * Exception handling. 5 * 6 * Derived from code with the following copyrights: 7 * Copyright (C) 1994 - 1999 by Ralf Baechle 8 * Modified for R3000 by Paul M. Antoine, 1995, 1996 9 * Complete output from die() by Ulf Carlsson, 1998 10 * Copyright (C) 1999 Silicon Graphics, Inc. 11 * 12 * Essentially rewritten for the Xtensa architecture port. 13 * 14 * Copyright (C) 2001 - 2013 Tensilica Inc. 15 * 16 * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com> 17 * Chris Zankel <chris@zankel.net> 18 * Marc Gauthier<marc@tensilica.com, marc@alumni.uwaterloo.ca> 19 * Kevin Chea 20 * 21 * This file is subject to the terms and conditions of the GNU General Public 22 * License. See the file "COPYING" in the main directory of this archive 23 * for more details. 24 */ 25 26 #include <linux/kernel.h> 27 #include <linux/sched/signal.h> 28 #include <linux/sched/debug.h> 29 #include <linux/sched/task_stack.h> 30 #include <linux/init.h> 31 #include <linux/module.h> 32 #include <linux/stringify.h> 33 #include <linux/kallsyms.h> 34 #include <linux/delay.h> 35 #include <linux/hardirq.h> 36 #include <linux/ratelimit.h> 37 #include <linux/pgtable.h> 38 39 #include <asm/stacktrace.h> 40 #include <asm/ptrace.h> 41 #include <asm/timex.h> 42 #include <linux/uaccess.h> 43 #include <asm/processor.h> 44 #include <asm/traps.h> 45 #include <asm/hw_breakpoint.h> 46 47 /* 48 * Machine specific interrupt handlers 49 */ 50 51 static void do_illegal_instruction(struct pt_regs *regs); 52 static void do_div0(struct pt_regs *regs); 53 static void do_interrupt(struct pt_regs *regs); 54 #if XTENSA_FAKE_NMI 55 static void do_nmi(struct pt_regs *regs); 56 #endif 57 #ifdef CONFIG_XTENSA_LOAD_STORE 58 static void do_load_store(struct pt_regs *regs); 59 #endif 60 static void do_unaligned_user(struct pt_regs *regs); 61 static void do_multihit(struct pt_regs *regs); 62 #if XTENSA_HAVE_COPROCESSORS 63 static void do_coprocessor(struct pt_regs *regs); 64 #endif 65 static void do_debug(struct pt_regs *regs); 66 67 /* 68 * The vector table must be preceded by a save area (which 69 * implies it must be in RAM, unless one places RAM immediately 70 * before a ROM and puts the vector at the start of the ROM (!)) 71 */ 72 73 #define KRNL 0x01 74 #define USER 0x02 75 76 #define COPROCESSOR(x) \ 77 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER|KRNL, fast_coprocessor },\ 78 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, 0, do_coprocessor } 79 80 typedef struct { 81 int cause; 82 int fast; 83 void* handler; 84 } dispatch_init_table_t; 85 86 static dispatch_init_table_t __initdata dispatch_init_table[] = { 87 88 #ifdef CONFIG_USER_ABI_CALL0_PROBE 89 { EXCCAUSE_ILLEGAL_INSTRUCTION, USER, fast_illegal_instruction_user }, 90 #endif 91 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction}, 92 { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user }, 93 { EXCCAUSE_SYSTEM_CALL, 0, system_call }, 94 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */ 95 #ifdef CONFIG_XTENSA_LOAD_STORE 96 { EXCCAUSE_LOAD_STORE_ERROR, USER|KRNL, fast_load_store }, 97 { EXCCAUSE_LOAD_STORE_ERROR, 0, do_load_store }, 98 #endif 99 { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt }, 100 #ifdef SUPPORT_WINDOWED 101 { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca }, 102 #endif 103 { EXCCAUSE_INTEGER_DIVIDE_BY_ZERO, 0, do_div0 }, 104 /* EXCCAUSE_PRIVILEGED unhandled */ 105 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION || \ 106 IS_ENABLED(CONFIG_XTENSA_LOAD_STORE) 107 #ifdef CONFIG_XTENSA_UNALIGNED_USER 108 { EXCCAUSE_UNALIGNED, USER, fast_unaligned }, 109 #endif 110 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, 111 #endif 112 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 113 #ifdef CONFIG_MMU 114 { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 115 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 116 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 117 { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 118 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 119 #endif /* CONFIG_MMU */ 120 #ifdef CONFIG_PFAULT 121 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 122 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 123 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 124 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 125 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 126 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 127 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 128 #endif 129 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 130 #if XTENSA_HAVE_COPROCESSOR(0) 131 COPROCESSOR(0), 132 #endif 133 #if XTENSA_HAVE_COPROCESSOR(1) 134 COPROCESSOR(1), 135 #endif 136 #if XTENSA_HAVE_COPROCESSOR(2) 137 COPROCESSOR(2), 138 #endif 139 #if XTENSA_HAVE_COPROCESSOR(3) 140 COPROCESSOR(3), 141 #endif 142 #if XTENSA_HAVE_COPROCESSOR(4) 143 COPROCESSOR(4), 144 #endif 145 #if XTENSA_HAVE_COPROCESSOR(5) 146 COPROCESSOR(5), 147 #endif 148 #if XTENSA_HAVE_COPROCESSOR(6) 149 COPROCESSOR(6), 150 #endif 151 #if XTENSA_HAVE_COPROCESSOR(7) 152 COPROCESSOR(7), 153 #endif 154 #if XTENSA_FAKE_NMI 155 { EXCCAUSE_MAPPED_NMI, 0, do_nmi }, 156 #endif 157 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 158 { -1, -1, 0 } 159 160 }; 161 162 /* The exception table <exc_table> serves two functions: 163 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 164 * 2. it is a temporary memory buffer for the exception handlers. 165 */ 166 167 DEFINE_PER_CPU(struct exc_table, exc_table); 168 DEFINE_PER_CPU(struct debug_table, debug_table); 169 170 void die(const char*, struct pt_regs*, long); 171 172 static inline void 173 __die_if_kernel(const char *str, struct pt_regs *regs, long err) 174 { 175 if (!user_mode(regs)) 176 die(str, regs, err); 177 } 178 179 #ifdef CONFIG_PRINT_USER_CODE_ON_UNHANDLED_EXCEPTION 180 static inline void dump_user_code(struct pt_regs *regs) 181 { 182 char buf[32]; 183 184 if (copy_from_user(buf, (void __user *)(regs->pc & -16), sizeof(buf)) == 0) { 185 print_hex_dump(KERN_INFO, " ", DUMP_PREFIX_NONE, 186 32, 1, buf, sizeof(buf), false); 187 188 } 189 } 190 #else 191 static inline void dump_user_code(struct pt_regs *regs) 192 { 193 } 194 #endif 195 196 /* 197 * Unhandled Exceptions. Kill user task or panic if in kernel space. 198 */ 199 200 void do_unhandled(struct pt_regs *regs) 201 { 202 __die_if_kernel("Caught unhandled exception - should not happen", 203 regs, SIGKILL); 204 205 /* If in user mode, send SIGILL signal to current process */ 206 pr_info_ratelimited("Caught unhandled exception in '%s' " 207 "(pid = %d, pc = %#010lx) - should not happen\n" 208 "\tEXCCAUSE is %ld\n", 209 current->comm, task_pid_nr(current), regs->pc, 210 regs->exccause); 211 dump_user_code(regs); 212 force_sig(SIGILL); 213 } 214 215 /* 216 * Multi-hit exception. This if fatal! 217 */ 218 219 static void do_multihit(struct pt_regs *regs) 220 { 221 die("Caught multihit exception", regs, SIGKILL); 222 } 223 224 /* 225 * IRQ handler. 226 */ 227 228 #if XTENSA_FAKE_NMI 229 230 #define IS_POW2(v) (((v) & ((v) - 1)) == 0) 231 232 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \ 233 IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL))) 234 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level." 235 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire." 236 237 static inline void check_valid_nmi(void) 238 { 239 unsigned intread = xtensa_get_sr(interrupt); 240 unsigned intenable = xtensa_get_sr(intenable); 241 242 BUG_ON(intread & intenable & 243 ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^ 244 XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^ 245 BIT(XCHAL_PROFILING_INTERRUPT))); 246 } 247 248 #else 249 250 static inline void check_valid_nmi(void) 251 { 252 } 253 254 #endif 255 256 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id); 257 258 DEFINE_PER_CPU(unsigned long, nmi_count); 259 260 static void do_nmi(struct pt_regs *regs) 261 { 262 struct pt_regs *old_regs = set_irq_regs(regs); 263 264 nmi_enter(); 265 ++*this_cpu_ptr(&nmi_count); 266 check_valid_nmi(); 267 xtensa_pmu_irq_handler(0, NULL); 268 nmi_exit(); 269 set_irq_regs(old_regs); 270 } 271 #endif 272 273 static void do_interrupt(struct pt_regs *regs) 274 { 275 static const unsigned int_level_mask[] = { 276 0, 277 XCHAL_INTLEVEL1_MASK, 278 XCHAL_INTLEVEL2_MASK, 279 XCHAL_INTLEVEL3_MASK, 280 XCHAL_INTLEVEL4_MASK, 281 XCHAL_INTLEVEL5_MASK, 282 XCHAL_INTLEVEL6_MASK, 283 XCHAL_INTLEVEL7_MASK, 284 }; 285 struct pt_regs *old_regs = set_irq_regs(regs); 286 unsigned unhandled = ~0u; 287 288 irq_enter(); 289 290 for (;;) { 291 unsigned intread = xtensa_get_sr(interrupt); 292 unsigned intenable = xtensa_get_sr(intenable); 293 unsigned int_at_level = intread & intenable; 294 unsigned level; 295 296 for (level = LOCKLEVEL; level > 0; --level) { 297 if (int_at_level & int_level_mask[level]) { 298 int_at_level &= int_level_mask[level]; 299 if (int_at_level & unhandled) 300 int_at_level &= unhandled; 301 else 302 unhandled |= int_level_mask[level]; 303 break; 304 } 305 } 306 307 if (level == 0) 308 break; 309 310 /* clear lowest pending irq in the unhandled mask */ 311 unhandled ^= (int_at_level & -int_at_level); 312 do_IRQ(__ffs(int_at_level), regs); 313 } 314 315 irq_exit(); 316 set_irq_regs(old_regs); 317 } 318 319 static bool check_div0(struct pt_regs *regs) 320 { 321 static const u8 pattern[] = {'D', 'I', 'V', '0'}; 322 const u8 *p; 323 u8 buf[5]; 324 325 if (user_mode(regs)) { 326 if (copy_from_user(buf, (void __user *)regs->pc + 2, 5)) 327 return false; 328 p = buf; 329 } else { 330 p = (const u8 *)regs->pc + 2; 331 } 332 333 return memcmp(p, pattern, sizeof(pattern)) == 0 || 334 memcmp(p + 1, pattern, sizeof(pattern)) == 0; 335 } 336 337 /* 338 * Illegal instruction. Fatal if in kernel space. 339 */ 340 341 static void do_illegal_instruction(struct pt_regs *regs) 342 { 343 #ifdef CONFIG_USER_ABI_CALL0_PROBE 344 /* 345 * When call0 application encounters an illegal instruction fast 346 * exception handler will attempt to set PS.WOE and retry failing 347 * instruction. 348 * If we get here we know that that instruction is also illegal 349 * with PS.WOE set, so it's not related to the windowed option 350 * hence PS.WOE may be cleared. 351 */ 352 if (regs->pc == current_thread_info()->ps_woe_fix_addr) 353 regs->ps &= ~PS_WOE_MASK; 354 #endif 355 if (check_div0(regs)) { 356 do_div0(regs); 357 return; 358 } 359 360 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 361 362 /* If in user mode, send SIGILL signal to current process. */ 363 364 pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 365 current->comm, task_pid_nr(current), regs->pc); 366 force_sig(SIGILL); 367 } 368 369 static void do_div0(struct pt_regs *regs) 370 { 371 __die_if_kernel("Unhandled division by 0 in kernel", regs, SIGKILL); 372 force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->pc); 373 } 374 375 #ifdef CONFIG_XTENSA_LOAD_STORE 376 static void do_load_store(struct pt_regs *regs) 377 { 378 __die_if_kernel("Unhandled load/store exception in kernel", 379 regs, SIGKILL); 380 381 pr_info_ratelimited("Load/store error to %08lx in '%s' (pid = %d, pc = %#010lx)\n", 382 regs->excvaddr, current->comm, 383 task_pid_nr(current), regs->pc); 384 force_sig_fault(SIGBUS, BUS_ADRERR, (void *)regs->excvaddr); 385 } 386 #endif 387 388 /* 389 * Handle unaligned memory accesses from user space. Kill task. 390 * 391 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 392 * accesses causes from user space. 393 */ 394 395 static void do_unaligned_user(struct pt_regs *regs) 396 { 397 __die_if_kernel("Unhandled unaligned exception in kernel", 398 regs, SIGKILL); 399 400 pr_info_ratelimited("Unaligned memory access to %08lx in '%s' " 401 "(pid = %d, pc = %#010lx)\n", 402 regs->excvaddr, current->comm, 403 task_pid_nr(current), regs->pc); 404 force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr); 405 } 406 407 #if XTENSA_HAVE_COPROCESSORS 408 static void do_coprocessor(struct pt_regs *regs) 409 { 410 coprocessor_flush_release_all(current_thread_info()); 411 } 412 #endif 413 414 /* Handle debug events. 415 * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with 416 * preemption disabled to avoid rescheduling and keep mapping of hardware 417 * breakpoint structures to debug registers intact, so that 418 * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit. 419 */ 420 static void do_debug(struct pt_regs *regs) 421 { 422 #ifdef CONFIG_HAVE_HW_BREAKPOINT 423 int ret = check_hw_breakpoint(regs); 424 425 preempt_enable(); 426 if (ret == 0) 427 return; 428 #endif 429 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 430 431 /* If in user mode, send SIGTRAP signal to current process */ 432 433 force_sig(SIGTRAP); 434 } 435 436 437 #define set_handler(type, cause, handler) \ 438 do { \ 439 unsigned int cpu; \ 440 \ 441 for_each_possible_cpu(cpu) \ 442 per_cpu(exc_table, cpu).type[cause] = (handler);\ 443 } while (0) 444 445 /* Set exception C handler - for temporary use when probing exceptions */ 446 447 xtensa_exception_handler * 448 __init trap_set_handler(int cause, xtensa_exception_handler *handler) 449 { 450 void *previous = per_cpu(exc_table, 0).default_handler[cause]; 451 452 set_handler(default_handler, cause, handler); 453 return previous; 454 } 455 456 457 static void trap_init_excsave(void) 458 { 459 xtensa_set_sr(this_cpu_ptr(&exc_table), excsave1); 460 } 461 462 static void trap_init_debug(void) 463 { 464 unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table); 465 466 this_cpu_ptr(&debug_table)->debug_exception = debug_exception; 467 __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL) 468 :: "a"(debugsave)); 469 } 470 471 /* 472 * Initialize dispatch tables. 473 * 474 * The exception vectors are stored compressed the __init section in the 475 * dispatch_init_table. This function initializes the following three tables 476 * from that compressed table: 477 * - fast user first dispatch table for user exceptions 478 * - fast kernel first dispatch table for kernel exceptions 479 * - default C-handler C-handler called by the default fast handler. 480 * 481 * See vectors.S for more details. 482 */ 483 484 void __init trap_init(void) 485 { 486 int i; 487 488 /* Setup default vectors. */ 489 490 for (i = 0; i < EXCCAUSE_N; i++) { 491 set_handler(fast_user_handler, i, user_exception); 492 set_handler(fast_kernel_handler, i, kernel_exception); 493 set_handler(default_handler, i, do_unhandled); 494 } 495 496 /* Setup specific handlers. */ 497 498 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 499 int fast = dispatch_init_table[i].fast; 500 int cause = dispatch_init_table[i].cause; 501 void *handler = dispatch_init_table[i].handler; 502 503 if (fast == 0) 504 set_handler(default_handler, cause, handler); 505 if ((fast & USER) != 0) 506 set_handler(fast_user_handler, cause, handler); 507 if ((fast & KRNL) != 0) 508 set_handler(fast_kernel_handler, cause, handler); 509 } 510 511 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 512 trap_init_excsave(); 513 trap_init_debug(); 514 } 515 516 #ifdef CONFIG_SMP 517 void secondary_trap_init(void) 518 { 519 trap_init_excsave(); 520 trap_init_debug(); 521 } 522 #endif 523 524 /* 525 * This function dumps the current valid window frame and other base registers. 526 */ 527 528 void show_regs(struct pt_regs * regs) 529 { 530 int i; 531 532 show_regs_print_info(KERN_DEFAULT); 533 534 for (i = 0; i < 16; i++) { 535 if ((i % 8) == 0) 536 pr_info("a%02d:", i); 537 pr_cont(" %08lx", regs->areg[i]); 538 } 539 pr_cont("\n"); 540 pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 541 regs->pc, regs->ps, regs->depc, regs->excvaddr); 542 pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 543 regs->lbeg, regs->lend, regs->lcount, regs->sar); 544 if (user_mode(regs)) 545 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 546 regs->windowbase, regs->windowstart, regs->wmask, 547 regs->syscall); 548 } 549 550 static int show_trace_cb(struct stackframe *frame, void *data) 551 { 552 const char *loglvl = data; 553 554 if (kernel_text_address(frame->pc)) 555 printk("%s [<%08lx>] %pB\n", 556 loglvl, frame->pc, (void *)frame->pc); 557 return 0; 558 } 559 560 static void show_trace(struct task_struct *task, unsigned long *sp, 561 const char *loglvl) 562 { 563 if (!sp) 564 sp = stack_pointer(task); 565 566 printk("%sCall Trace:\n", loglvl); 567 walk_stackframe(sp, show_trace_cb, (void *)loglvl); 568 } 569 570 #define STACK_DUMP_ENTRY_SIZE 4 571 #define STACK_DUMP_LINE_SIZE 16 572 static size_t kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH; 573 574 struct stack_fragment 575 { 576 size_t len; 577 size_t off; 578 u8 *sp; 579 const char *loglvl; 580 }; 581 582 static int show_stack_fragment_cb(struct stackframe *frame, void *data) 583 { 584 struct stack_fragment *sf = data; 585 586 while (sf->off < sf->len) { 587 u8 line[STACK_DUMP_LINE_SIZE]; 588 size_t line_len = sf->len - sf->off > STACK_DUMP_LINE_SIZE ? 589 STACK_DUMP_LINE_SIZE : sf->len - sf->off; 590 bool arrow = sf->off == 0; 591 592 if (frame && frame->sp == (unsigned long)(sf->sp + sf->off)) 593 arrow = true; 594 595 __memcpy(line, sf->sp + sf->off, line_len); 596 print_hex_dump(sf->loglvl, arrow ? "> " : " ", DUMP_PREFIX_NONE, 597 STACK_DUMP_LINE_SIZE, STACK_DUMP_ENTRY_SIZE, 598 line, line_len, false); 599 sf->off += STACK_DUMP_LINE_SIZE; 600 if (arrow) 601 return 0; 602 } 603 return 1; 604 } 605 606 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl) 607 { 608 struct stack_fragment sf; 609 610 if (!sp) 611 sp = stack_pointer(task); 612 613 sf.len = min((-(size_t)sp) & (THREAD_SIZE - STACK_DUMP_ENTRY_SIZE), 614 kstack_depth_to_print * STACK_DUMP_ENTRY_SIZE); 615 sf.off = 0; 616 sf.sp = (u8 *)sp; 617 sf.loglvl = loglvl; 618 619 printk("%sStack:\n", loglvl); 620 walk_stackframe(sp, show_stack_fragment_cb, &sf); 621 while (sf.off < sf.len) 622 show_stack_fragment_cb(NULL, &sf); 623 show_trace(task, sp, loglvl); 624 } 625 626 DEFINE_SPINLOCK(die_lock); 627 628 void __noreturn die(const char * str, struct pt_regs * regs, long err) 629 { 630 static int die_counter; 631 const char *pr = ""; 632 633 if (IS_ENABLED(CONFIG_PREEMPTION)) 634 pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT"; 635 636 console_verbose(); 637 spin_lock_irq(&die_lock); 638 639 pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, pr); 640 show_regs(regs); 641 if (!user_mode(regs)) 642 show_stack(NULL, (unsigned long *)regs->areg[1], KERN_INFO); 643 644 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 645 spin_unlock_irq(&die_lock); 646 647 if (in_interrupt()) 648 panic("Fatal exception in interrupt"); 649 650 if (panic_on_oops) 651 panic("Fatal exception"); 652 653 make_task_dead(err); 654 } 655