1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/arch/arm/kernel/traps.c 4 * 5 * Copyright (C) 1995-2009 Russell King 6 * Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds 7 * 8 * 'traps.c' handles hardware exceptions after we have saved some state in 9 * 'linux/arch/arm/lib/traps.S'. Mostly a debugging aid, but will probably 10 * kill the offending process. 11 */ 12 #include <linux/signal.h> 13 #include <linux/personality.h> 14 #include <linux/kallsyms.h> 15 #include <linux/spinlock.h> 16 #include <linux/uaccess.h> 17 #include <linux/hardirq.h> 18 #include <linux/kdebug.h> 19 #include <linux/kprobes.h> 20 #include <linux/module.h> 21 #include <linux/kexec.h> 22 #include <linux/bug.h> 23 #include <linux/delay.h> 24 #include <linux/init.h> 25 #include <linux/sched/signal.h> 26 #include <linux/sched/debug.h> 27 #include <linux/sched/task_stack.h> 28 #include <linux/irq.h> 29 30 #include <linux/atomic.h> 31 #include <asm/cacheflush.h> 32 #include <asm/exception.h> 33 #include <asm/unistd.h> 34 #include <asm/traps.h> 35 #include <asm/ptrace.h> 36 #include <asm/unwind.h> 37 #include <asm/tls.h> 38 #include <asm/system_misc.h> 39 #include <asm/opcodes.h> 40 41 42 static const char *handler[]= { 43 "prefetch abort", 44 "data abort", 45 "address exception", 46 "interrupt", 47 "undefined instruction", 48 }; 49 50 void *vectors_page; 51 52 #ifdef CONFIG_DEBUG_USER 53 unsigned int user_debug; 54 55 static int __init user_debug_setup(char *str) 56 { 57 get_option(&str, &user_debug); 58 return 1; 59 } 60 __setup("user_debug=", user_debug_setup); 61 #endif 62 63 static void dump_mem(const char *, const char *, unsigned long, unsigned long); 64 65 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame) 66 { 67 #ifdef CONFIG_KALLSYMS 68 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from); 69 #else 70 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from); 71 #endif 72 73 if (in_entry_text(from)) 74 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs)); 75 } 76 77 void dump_backtrace_stm(u32 *stack, u32 instruction) 78 { 79 char str[80], *p; 80 unsigned int x; 81 int reg; 82 83 for (reg = 10, x = 0, p = str; reg >= 0; reg--) { 84 if (instruction & BIT(reg)) { 85 p += sprintf(p, " r%d:%08x", reg, *stack--); 86 if (++x == 6) { 87 x = 0; 88 p = str; 89 printk("%s\n", str); 90 } 91 } 92 } 93 if (p != str) 94 printk("%s\n", str); 95 } 96 97 #ifndef CONFIG_ARM_UNWIND 98 /* 99 * Stack pointers should always be within the kernels view of 100 * physical memory. If it is not there, then we can't dump 101 * out any information relating to the stack. 102 */ 103 static int verify_stack(unsigned long sp) 104 { 105 if (sp < PAGE_OFFSET || 106 (sp > (unsigned long)high_memory && high_memory != NULL)) 107 return -EFAULT; 108 109 return 0; 110 } 111 #endif 112 113 /* 114 * Dump out the contents of some memory nicely... 115 */ 116 static void dump_mem(const char *lvl, const char *str, unsigned long bottom, 117 unsigned long top) 118 { 119 unsigned long first; 120 mm_segment_t fs; 121 int i; 122 123 /* 124 * We need to switch to kernel mode so that we can use __get_user 125 * to safely read from kernel space. Note that we now dump the 126 * code first, just in case the backtrace kills us. 127 */ 128 fs = get_fs(); 129 set_fs(KERNEL_DS); 130 131 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top); 132 133 for (first = bottom & ~31; first < top; first += 32) { 134 unsigned long p; 135 char str[sizeof(" 12345678") * 8 + 1]; 136 137 memset(str, ' ', sizeof(str)); 138 str[sizeof(str) - 1] = '\0'; 139 140 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) { 141 if (p >= bottom && p < top) { 142 unsigned long val; 143 if (__get_user(val, (unsigned long *)p) == 0) 144 sprintf(str + i * 9, " %08lx", val); 145 else 146 sprintf(str + i * 9, " ????????"); 147 } 148 } 149 printk("%s%04lx:%s\n", lvl, first & 0xffff, str); 150 } 151 152 set_fs(fs); 153 } 154 155 static void __dump_instr(const char *lvl, struct pt_regs *regs) 156 { 157 unsigned long addr = instruction_pointer(regs); 158 const int thumb = thumb_mode(regs); 159 const int width = thumb ? 4 : 8; 160 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str; 161 int i; 162 163 /* 164 * Note that we now dump the code first, just in case the backtrace 165 * kills us. 166 */ 167 168 for (i = -4; i < 1 + !!thumb; i++) { 169 unsigned int val, bad; 170 171 if (thumb) 172 bad = get_user(val, &((u16 *)addr)[i]); 173 else 174 bad = get_user(val, &((u32 *)addr)[i]); 175 176 if (!bad) 177 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ", 178 width, val); 179 else { 180 p += sprintf(p, "bad PC value"); 181 break; 182 } 183 } 184 printk("%sCode: %s\n", lvl, str); 185 } 186 187 static void dump_instr(const char *lvl, struct pt_regs *regs) 188 { 189 mm_segment_t fs; 190 191 if (!user_mode(regs)) { 192 fs = get_fs(); 193 set_fs(KERNEL_DS); 194 __dump_instr(lvl, regs); 195 set_fs(fs); 196 } else { 197 __dump_instr(lvl, regs); 198 } 199 } 200 201 #ifdef CONFIG_ARM_UNWIND 202 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) 203 { 204 unwind_backtrace(regs, tsk); 205 } 206 #else 207 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) 208 { 209 unsigned int fp, mode; 210 int ok = 1; 211 212 printk("Backtrace: "); 213 214 if (!tsk) 215 tsk = current; 216 217 if (regs) { 218 fp = frame_pointer(regs); 219 mode = processor_mode(regs); 220 } else if (tsk != current) { 221 fp = thread_saved_fp(tsk); 222 mode = 0x10; 223 } else { 224 asm("mov %0, fp" : "=r" (fp) : : "cc"); 225 mode = 0x10; 226 } 227 228 if (!fp) { 229 pr_cont("no frame pointer"); 230 ok = 0; 231 } else if (verify_stack(fp)) { 232 pr_cont("invalid frame pointer 0x%08x", fp); 233 ok = 0; 234 } else if (fp < (unsigned long)end_of_stack(tsk)) 235 pr_cont("frame pointer underflow"); 236 pr_cont("\n"); 237 238 if (ok) 239 c_backtrace(fp, mode); 240 } 241 #endif 242 243 void show_stack(struct task_struct *tsk, unsigned long *sp) 244 { 245 dump_backtrace(NULL, tsk); 246 barrier(); 247 } 248 249 #ifdef CONFIG_PREEMPT 250 #define S_PREEMPT " PREEMPT" 251 #else 252 #define S_PREEMPT "" 253 #endif 254 #ifdef CONFIG_SMP 255 #define S_SMP " SMP" 256 #else 257 #define S_SMP "" 258 #endif 259 #ifdef CONFIG_THUMB2_KERNEL 260 #define S_ISA " THUMB2" 261 #else 262 #define S_ISA " ARM" 263 #endif 264 265 static int __die(const char *str, int err, struct pt_regs *regs) 266 { 267 struct task_struct *tsk = current; 268 static int die_counter; 269 int ret; 270 271 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n", 272 str, err, ++die_counter); 273 274 /* trap and error numbers are mostly meaningless on ARM */ 275 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV); 276 if (ret == NOTIFY_STOP) 277 return 1; 278 279 print_modules(); 280 __show_regs(regs); 281 pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n", 282 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk)); 283 284 if (!user_mode(regs) || in_interrupt()) { 285 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp, 286 THREAD_SIZE + (unsigned long)task_stack_page(tsk)); 287 dump_backtrace(regs, tsk); 288 dump_instr(KERN_EMERG, regs); 289 } 290 291 return 0; 292 } 293 294 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED; 295 static int die_owner = -1; 296 static unsigned int die_nest_count; 297 298 static unsigned long oops_begin(void) 299 { 300 int cpu; 301 unsigned long flags; 302 303 oops_enter(); 304 305 /* racy, but better than risking deadlock. */ 306 raw_local_irq_save(flags); 307 cpu = smp_processor_id(); 308 if (!arch_spin_trylock(&die_lock)) { 309 if (cpu == die_owner) 310 /* nested oops. should stop eventually */; 311 else 312 arch_spin_lock(&die_lock); 313 } 314 die_nest_count++; 315 die_owner = cpu; 316 console_verbose(); 317 bust_spinlocks(1); 318 return flags; 319 } 320 321 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr) 322 { 323 if (regs && kexec_should_crash(current)) 324 crash_kexec(regs); 325 326 bust_spinlocks(0); 327 die_owner = -1; 328 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 329 die_nest_count--; 330 if (!die_nest_count) 331 /* Nest count reaches zero, release the lock. */ 332 arch_spin_unlock(&die_lock); 333 raw_local_irq_restore(flags); 334 oops_exit(); 335 336 if (in_interrupt()) 337 panic("Fatal exception in interrupt"); 338 if (panic_on_oops) 339 panic("Fatal exception"); 340 if (signr) 341 do_exit(signr); 342 } 343 344 /* 345 * This function is protected against re-entrancy. 346 */ 347 void die(const char *str, struct pt_regs *regs, int err) 348 { 349 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE; 350 unsigned long flags = oops_begin(); 351 int sig = SIGSEGV; 352 353 if (!user_mode(regs)) 354 bug_type = report_bug(regs->ARM_pc, regs); 355 if (bug_type != BUG_TRAP_TYPE_NONE) 356 str = "Oops - BUG"; 357 358 if (__die(str, err, regs)) 359 sig = 0; 360 361 oops_end(flags, regs, sig); 362 } 363 364 void arm_notify_die(const char *str, struct pt_regs *regs, 365 int signo, int si_code, void __user *addr, 366 unsigned long err, unsigned long trap) 367 { 368 if (user_mode(regs)) { 369 current->thread.error_code = err; 370 current->thread.trap_no = trap; 371 372 force_sig_fault(signo, si_code, addr); 373 } else { 374 die(str, regs, err); 375 } 376 } 377 378 #ifdef CONFIG_GENERIC_BUG 379 380 int is_valid_bugaddr(unsigned long pc) 381 { 382 #ifdef CONFIG_THUMB2_KERNEL 383 u16 bkpt; 384 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE); 385 #else 386 u32 bkpt; 387 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE); 388 #endif 389 390 if (probe_kernel_address((unsigned *)pc, bkpt)) 391 return 0; 392 393 return bkpt == insn; 394 } 395 396 #endif 397 398 static LIST_HEAD(undef_hook); 399 static DEFINE_RAW_SPINLOCK(undef_lock); 400 401 void register_undef_hook(struct undef_hook *hook) 402 { 403 unsigned long flags; 404 405 raw_spin_lock_irqsave(&undef_lock, flags); 406 list_add(&hook->node, &undef_hook); 407 raw_spin_unlock_irqrestore(&undef_lock, flags); 408 } 409 410 void unregister_undef_hook(struct undef_hook *hook) 411 { 412 unsigned long flags; 413 414 raw_spin_lock_irqsave(&undef_lock, flags); 415 list_del(&hook->node); 416 raw_spin_unlock_irqrestore(&undef_lock, flags); 417 } 418 419 static nokprobe_inline 420 int call_undef_hook(struct pt_regs *regs, unsigned int instr) 421 { 422 struct undef_hook *hook; 423 unsigned long flags; 424 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL; 425 426 raw_spin_lock_irqsave(&undef_lock, flags); 427 list_for_each_entry(hook, &undef_hook, node) 428 if ((instr & hook->instr_mask) == hook->instr_val && 429 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val) 430 fn = hook->fn; 431 raw_spin_unlock_irqrestore(&undef_lock, flags); 432 433 return fn ? fn(regs, instr) : 1; 434 } 435 436 asmlinkage void do_undefinstr(struct pt_regs *regs) 437 { 438 unsigned int instr; 439 void __user *pc; 440 441 pc = (void __user *)instruction_pointer(regs); 442 443 if (processor_mode(regs) == SVC_MODE) { 444 #ifdef CONFIG_THUMB2_KERNEL 445 if (thumb_mode(regs)) { 446 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]); 447 if (is_wide_instruction(instr)) { 448 u16 inst2; 449 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]); 450 instr = __opcode_thumb32_compose(instr, inst2); 451 } 452 } else 453 #endif 454 instr = __mem_to_opcode_arm(*(u32 *) pc); 455 } else if (thumb_mode(regs)) { 456 if (get_user(instr, (u16 __user *)pc)) 457 goto die_sig; 458 instr = __mem_to_opcode_thumb16(instr); 459 if (is_wide_instruction(instr)) { 460 unsigned int instr2; 461 if (get_user(instr2, (u16 __user *)pc+1)) 462 goto die_sig; 463 instr2 = __mem_to_opcode_thumb16(instr2); 464 instr = __opcode_thumb32_compose(instr, instr2); 465 } 466 } else { 467 if (get_user(instr, (u32 __user *)pc)) 468 goto die_sig; 469 instr = __mem_to_opcode_arm(instr); 470 } 471 472 if (call_undef_hook(regs, instr) == 0) 473 return; 474 475 die_sig: 476 #ifdef CONFIG_DEBUG_USER 477 if (user_debug & UDBG_UNDEFINED) { 478 pr_info("%s (%d): undefined instruction: pc=%p\n", 479 current->comm, task_pid_nr(current), pc); 480 __show_regs(regs); 481 dump_instr(KERN_INFO, regs); 482 } 483 #endif 484 arm_notify_die("Oops - undefined instruction", regs, 485 SIGILL, ILL_ILLOPC, pc, 0, 6); 486 } 487 NOKPROBE_SYMBOL(do_undefinstr) 488 489 /* 490 * Handle FIQ similarly to NMI on x86 systems. 491 * 492 * The runtime environment for NMIs is extremely restrictive 493 * (NMIs can pre-empt critical sections meaning almost all locking is 494 * forbidden) meaning this default FIQ handling must only be used in 495 * circumstances where non-maskability improves robustness, such as 496 * watchdog or debug logic. 497 * 498 * This handler is not appropriate for general purpose use in drivers 499 * platform code and can be overrideen using set_fiq_handler. 500 */ 501 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs) 502 { 503 struct pt_regs *old_regs = set_irq_regs(regs); 504 505 nmi_enter(); 506 507 /* nop. FIQ handlers for special arch/arm features can be added here. */ 508 509 nmi_exit(); 510 511 set_irq_regs(old_regs); 512 } 513 514 /* 515 * bad_mode handles the impossible case in the vectors. If you see one of 516 * these, then it's extremely serious, and could mean you have buggy hardware. 517 * It never returns, and never tries to sync. We hope that we can at least 518 * dump out some state information... 519 */ 520 asmlinkage void bad_mode(struct pt_regs *regs, int reason) 521 { 522 console_verbose(); 523 524 pr_crit("Bad mode in %s handler detected\n", handler[reason]); 525 526 die("Oops - bad mode", regs, 0); 527 local_irq_disable(); 528 panic("bad mode"); 529 } 530 531 static int bad_syscall(int n, struct pt_regs *regs) 532 { 533 if ((current->personality & PER_MASK) != PER_LINUX) { 534 send_sig(SIGSEGV, current, 1); 535 return regs->ARM_r0; 536 } 537 538 #ifdef CONFIG_DEBUG_USER 539 if (user_debug & UDBG_SYSCALL) { 540 pr_err("[%d] %s: obsolete system call %08x.\n", 541 task_pid_nr(current), current->comm, n); 542 dump_instr(KERN_ERR, regs); 543 } 544 #endif 545 546 arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP, 547 (void __user *)instruction_pointer(regs) - 548 (thumb_mode(regs) ? 2 : 4), 549 n, 0); 550 551 return regs->ARM_r0; 552 } 553 554 static inline int 555 __do_cache_op(unsigned long start, unsigned long end) 556 { 557 int ret; 558 559 do { 560 unsigned long chunk = min(PAGE_SIZE, end - start); 561 562 if (fatal_signal_pending(current)) 563 return 0; 564 565 ret = flush_cache_user_range(start, start + chunk); 566 if (ret) 567 return ret; 568 569 cond_resched(); 570 start += chunk; 571 } while (start < end); 572 573 return 0; 574 } 575 576 static inline int 577 do_cache_op(unsigned long start, unsigned long end, int flags) 578 { 579 if (end < start || flags) 580 return -EINVAL; 581 582 if (!access_ok(start, end - start)) 583 return -EFAULT; 584 585 return __do_cache_op(start, end); 586 } 587 588 /* 589 * Handle all unrecognised system calls. 590 * 0x9f0000 - 0x9fffff are some more esoteric system calls 591 */ 592 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE) 593 asmlinkage int arm_syscall(int no, struct pt_regs *regs) 594 { 595 if ((no >> 16) != (__ARM_NR_BASE>> 16)) 596 return bad_syscall(no, regs); 597 598 switch (no & 0xffff) { 599 case 0: /* branch through 0 */ 600 arm_notify_die("branch through zero", regs, 601 SIGSEGV, SEGV_MAPERR, NULL, 0, 0); 602 return 0; 603 604 case NR(breakpoint): /* SWI BREAK_POINT */ 605 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4; 606 ptrace_break(regs); 607 return regs->ARM_r0; 608 609 /* 610 * Flush a region from virtual address 'r0' to virtual address 'r1' 611 * _exclusive_. There is no alignment requirement on either address; 612 * user space does not need to know the hardware cache layout. 613 * 614 * r2 contains flags. It should ALWAYS be passed as ZERO until it 615 * is defined to be something else. For now we ignore it, but may 616 * the fires of hell burn in your belly if you break this rule. ;) 617 * 618 * (at a later date, we may want to allow this call to not flush 619 * various aspects of the cache. Passing '0' will guarantee that 620 * everything necessary gets flushed to maintain consistency in 621 * the specified region). 622 */ 623 case NR(cacheflush): 624 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2); 625 626 case NR(usr26): 627 if (!(elf_hwcap & HWCAP_26BIT)) 628 break; 629 regs->ARM_cpsr &= ~MODE32_BIT; 630 return regs->ARM_r0; 631 632 case NR(usr32): 633 if (!(elf_hwcap & HWCAP_26BIT)) 634 break; 635 regs->ARM_cpsr |= MODE32_BIT; 636 return regs->ARM_r0; 637 638 case NR(set_tls): 639 set_tls(regs->ARM_r0); 640 return 0; 641 642 case NR(get_tls): 643 return current_thread_info()->tp_value[0]; 644 645 default: 646 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS 647 if not implemented, rather than raising SIGILL. This 648 way the calling program can gracefully determine whether 649 a feature is supported. */ 650 if ((no & 0xffff) <= 0x7ff) 651 return -ENOSYS; 652 break; 653 } 654 #ifdef CONFIG_DEBUG_USER 655 /* 656 * experience shows that these seem to indicate that 657 * something catastrophic has happened 658 */ 659 if (user_debug & UDBG_SYSCALL) { 660 pr_err("[%d] %s: arm syscall %d\n", 661 task_pid_nr(current), current->comm, no); 662 dump_instr("", regs); 663 if (user_mode(regs)) { 664 __show_regs(regs); 665 c_backtrace(frame_pointer(regs), processor_mode(regs)); 666 } 667 } 668 #endif 669 arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP, 670 (void __user *)instruction_pointer(regs) - 671 (thumb_mode(regs) ? 2 : 4), 672 no, 0); 673 return 0; 674 } 675 676 #ifdef CONFIG_TLS_REG_EMUL 677 678 /* 679 * We might be running on an ARMv6+ processor which should have the TLS 680 * register but for some reason we can't use it, or maybe an SMP system 681 * using a pre-ARMv6 processor (there are apparently a few prototypes like 682 * that in existence) and therefore access to that register must be 683 * emulated. 684 */ 685 686 static int get_tp_trap(struct pt_regs *regs, unsigned int instr) 687 { 688 int reg = (instr >> 12) & 15; 689 if (reg == 15) 690 return 1; 691 regs->uregs[reg] = current_thread_info()->tp_value[0]; 692 regs->ARM_pc += 4; 693 return 0; 694 } 695 696 static struct undef_hook arm_mrc_hook = { 697 .instr_mask = 0x0fff0fff, 698 .instr_val = 0x0e1d0f70, 699 .cpsr_mask = PSR_T_BIT, 700 .cpsr_val = 0, 701 .fn = get_tp_trap, 702 }; 703 704 static int __init arm_mrc_hook_init(void) 705 { 706 register_undef_hook(&arm_mrc_hook); 707 return 0; 708 } 709 710 late_initcall(arm_mrc_hook_init); 711 712 #endif 713 714 /* 715 * A data abort trap was taken, but we did not handle the instruction. 716 * Try to abort the user program, or panic if it was the kernel. 717 */ 718 asmlinkage void 719 baddataabort(int code, unsigned long instr, struct pt_regs *regs) 720 { 721 unsigned long addr = instruction_pointer(regs); 722 723 #ifdef CONFIG_DEBUG_USER 724 if (user_debug & UDBG_BADABORT) { 725 pr_err("8<--- cut here ---\n"); 726 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n", 727 task_pid_nr(current), current->comm, code, instr); 728 dump_instr(KERN_ERR, regs); 729 show_pte(KERN_ERR, current->mm, addr); 730 } 731 #endif 732 733 arm_notify_die("unknown data abort code", regs, 734 SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0); 735 } 736 737 void __readwrite_bug(const char *fn) 738 { 739 pr_err("%s called, but not implemented\n", fn); 740 BUG(); 741 } 742 EXPORT_SYMBOL(__readwrite_bug); 743 744 void __pte_error(const char *file, int line, pte_t pte) 745 { 746 pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte)); 747 } 748 749 void __pmd_error(const char *file, int line, pmd_t pmd) 750 { 751 pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd)); 752 } 753 754 void __pgd_error(const char *file, int line, pgd_t pgd) 755 { 756 pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd)); 757 } 758 759 asmlinkage void __div0(void) 760 { 761 pr_err("Division by zero in kernel.\n"); 762 dump_stack(); 763 } 764 EXPORT_SYMBOL(__div0); 765 766 void abort(void) 767 { 768 BUG(); 769 770 /* if that doesn't kill us, halt */ 771 panic("Oops failed to kill thread"); 772 } 773 774 void __init trap_init(void) 775 { 776 return; 777 } 778 779 #ifdef CONFIG_KUSER_HELPERS 780 static void __init kuser_init(void *vectors) 781 { 782 extern char __kuser_helper_start[], __kuser_helper_end[]; 783 int kuser_sz = __kuser_helper_end - __kuser_helper_start; 784 785 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz); 786 787 /* 788 * vectors + 0xfe0 = __kuser_get_tls 789 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8 790 */ 791 if (tls_emu || has_tls_reg) 792 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4); 793 } 794 #else 795 static inline void __init kuser_init(void *vectors) 796 { 797 } 798 #endif 799 800 void __init early_trap_init(void *vectors_base) 801 { 802 #ifndef CONFIG_CPU_V7M 803 unsigned long vectors = (unsigned long)vectors_base; 804 extern char __stubs_start[], __stubs_end[]; 805 extern char __vectors_start[], __vectors_end[]; 806 unsigned i; 807 808 vectors_page = vectors_base; 809 810 /* 811 * Poison the vectors page with an undefined instruction. This 812 * instruction is chosen to be undefined for both ARM and Thumb 813 * ISAs. The Thumb version is an undefined instruction with a 814 * branch back to the undefined instruction. 815 */ 816 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++) 817 ((u32 *)vectors_base)[i] = 0xe7fddef1; 818 819 /* 820 * Copy the vectors, stubs and kuser helpers (in entry-armv.S) 821 * into the vector page, mapped at 0xffff0000, and ensure these 822 * are visible to the instruction stream. 823 */ 824 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start); 825 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start); 826 827 kuser_init(vectors_base); 828 829 flush_icache_range(vectors, vectors + PAGE_SIZE * 2); 830 #else /* ifndef CONFIG_CPU_V7M */ 831 /* 832 * on V7-M there is no need to copy the vector table to a dedicated 833 * memory area. The address is configurable and so a table in the kernel 834 * image can be used. 835 */ 836 #endif 837 } 838