1 /* 2 * linux/arch/arm/kernel/traps.c 3 * 4 * Copyright (C) 1995-2009 Russell King 5 * Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 * 'traps.c' handles hardware exceptions after we have saved some state in 12 * 'linux/arch/arm/lib/traps.S'. Mostly a debugging aid, but will probably 13 * kill the offending process. 14 */ 15 #include <linux/signal.h> 16 #include <linux/personality.h> 17 #include <linux/kallsyms.h> 18 #include <linux/spinlock.h> 19 #include <linux/uaccess.h> 20 #include <linux/hardirq.h> 21 #include <linux/kdebug.h> 22 #include <linux/module.h> 23 #include <linux/kexec.h> 24 #include <linux/bug.h> 25 #include <linux/delay.h> 26 #include <linux/init.h> 27 #include <linux/sched.h> 28 29 #include <linux/atomic.h> 30 #include <asm/cacheflush.h> 31 #include <asm/exception.h> 32 #include <asm/unistd.h> 33 #include <asm/traps.h> 34 #include <asm/unwind.h> 35 #include <asm/tls.h> 36 #include <asm/system_misc.h> 37 #include <asm/opcodes.h> 38 39 static const char *handler[]= { 40 "prefetch abort", 41 "data abort", 42 "address exception", 43 "interrupt", 44 "undefined instruction", 45 }; 46 47 void *vectors_page; 48 49 #ifdef CONFIG_DEBUG_USER 50 unsigned int user_debug; 51 52 static int __init user_debug_setup(char *str) 53 { 54 get_option(&str, &user_debug); 55 return 1; 56 } 57 __setup("user_debug=", user_debug_setup); 58 #endif 59 60 static void dump_mem(const char *, const char *, unsigned long, unsigned long); 61 62 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame) 63 { 64 #ifdef CONFIG_KALLSYMS 65 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from); 66 #else 67 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from); 68 #endif 69 70 if (in_exception_text(where)) 71 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs)); 72 } 73 74 #ifndef CONFIG_ARM_UNWIND 75 /* 76 * Stack pointers should always be within the kernels view of 77 * physical memory. If it is not there, then we can't dump 78 * out any information relating to the stack. 79 */ 80 static int verify_stack(unsigned long sp) 81 { 82 if (sp < PAGE_OFFSET || 83 (sp > (unsigned long)high_memory && high_memory != NULL)) 84 return -EFAULT; 85 86 return 0; 87 } 88 #endif 89 90 /* 91 * Dump out the contents of some memory nicely... 92 */ 93 static void dump_mem(const char *lvl, const char *str, unsigned long bottom, 94 unsigned long top) 95 { 96 unsigned long first; 97 mm_segment_t fs; 98 int i; 99 100 /* 101 * We need to switch to kernel mode so that we can use __get_user 102 * to safely read from kernel space. Note that we now dump the 103 * code first, just in case the backtrace kills us. 104 */ 105 fs = get_fs(); 106 set_fs(KERNEL_DS); 107 108 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top); 109 110 for (first = bottom & ~31; first < top; first += 32) { 111 unsigned long p; 112 char str[sizeof(" 12345678") * 8 + 1]; 113 114 memset(str, ' ', sizeof(str)); 115 str[sizeof(str) - 1] = '\0'; 116 117 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) { 118 if (p >= bottom && p < top) { 119 unsigned long val; 120 if (__get_user(val, (unsigned long *)p) == 0) 121 sprintf(str + i * 9, " %08lx", val); 122 else 123 sprintf(str + i * 9, " ????????"); 124 } 125 } 126 printk("%s%04lx:%s\n", lvl, first & 0xffff, str); 127 } 128 129 set_fs(fs); 130 } 131 132 static void dump_instr(const char *lvl, struct pt_regs *regs) 133 { 134 unsigned long addr = instruction_pointer(regs); 135 const int thumb = thumb_mode(regs); 136 const int width = thumb ? 4 : 8; 137 mm_segment_t fs; 138 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str; 139 int i; 140 141 /* 142 * We need to switch to kernel mode so that we can use __get_user 143 * to safely read from kernel space. Note that we now dump the 144 * code first, just in case the backtrace kills us. 145 */ 146 fs = get_fs(); 147 set_fs(KERNEL_DS); 148 149 for (i = -4; i < 1 + !!thumb; i++) { 150 unsigned int val, bad; 151 152 if (thumb) 153 bad = __get_user(val, &((u16 *)addr)[i]); 154 else 155 bad = __get_user(val, &((u32 *)addr)[i]); 156 157 if (!bad) 158 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ", 159 width, val); 160 else { 161 p += sprintf(p, "bad PC value"); 162 break; 163 } 164 } 165 printk("%sCode: %s\n", lvl, str); 166 167 set_fs(fs); 168 } 169 170 #ifdef CONFIG_ARM_UNWIND 171 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) 172 { 173 unwind_backtrace(regs, tsk); 174 } 175 #else 176 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) 177 { 178 unsigned int fp, mode; 179 int ok = 1; 180 181 printk("Backtrace: "); 182 183 if (!tsk) 184 tsk = current; 185 186 if (regs) { 187 fp = regs->ARM_fp; 188 mode = processor_mode(regs); 189 } else if (tsk != current) { 190 fp = thread_saved_fp(tsk); 191 mode = 0x10; 192 } else { 193 asm("mov %0, fp" : "=r" (fp) : : "cc"); 194 mode = 0x10; 195 } 196 197 if (!fp) { 198 printk("no frame pointer"); 199 ok = 0; 200 } else if (verify_stack(fp)) { 201 printk("invalid frame pointer 0x%08x", fp); 202 ok = 0; 203 } else if (fp < (unsigned long)end_of_stack(tsk)) 204 printk("frame pointer underflow"); 205 printk("\n"); 206 207 if (ok) 208 c_backtrace(fp, mode); 209 } 210 #endif 211 212 void show_stack(struct task_struct *tsk, unsigned long *sp) 213 { 214 dump_backtrace(NULL, tsk); 215 barrier(); 216 } 217 218 #ifdef CONFIG_PREEMPT 219 #define S_PREEMPT " PREEMPT" 220 #else 221 #define S_PREEMPT "" 222 #endif 223 #ifdef CONFIG_SMP 224 #define S_SMP " SMP" 225 #else 226 #define S_SMP "" 227 #endif 228 #ifdef CONFIG_THUMB2_KERNEL 229 #define S_ISA " THUMB2" 230 #else 231 #define S_ISA " ARM" 232 #endif 233 234 static int __die(const char *str, int err, struct pt_regs *regs) 235 { 236 struct task_struct *tsk = current; 237 static int die_counter; 238 int ret; 239 240 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP 241 S_ISA "\n", str, err, ++die_counter); 242 243 /* trap and error numbers are mostly meaningless on ARM */ 244 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV); 245 if (ret == NOTIFY_STOP) 246 return 1; 247 248 print_modules(); 249 __show_regs(regs); 250 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n", 251 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk)); 252 253 if (!user_mode(regs) || in_interrupt()) { 254 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp, 255 THREAD_SIZE + (unsigned long)task_stack_page(tsk)); 256 dump_backtrace(regs, tsk); 257 dump_instr(KERN_EMERG, regs); 258 } 259 260 return 0; 261 } 262 263 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED; 264 static int die_owner = -1; 265 static unsigned int die_nest_count; 266 267 static unsigned long oops_begin(void) 268 { 269 int cpu; 270 unsigned long flags; 271 272 oops_enter(); 273 274 /* racy, but better than risking deadlock. */ 275 raw_local_irq_save(flags); 276 cpu = smp_processor_id(); 277 if (!arch_spin_trylock(&die_lock)) { 278 if (cpu == die_owner) 279 /* nested oops. should stop eventually */; 280 else 281 arch_spin_lock(&die_lock); 282 } 283 die_nest_count++; 284 die_owner = cpu; 285 console_verbose(); 286 bust_spinlocks(1); 287 return flags; 288 } 289 290 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr) 291 { 292 if (regs && kexec_should_crash(current)) 293 crash_kexec(regs); 294 295 bust_spinlocks(0); 296 die_owner = -1; 297 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 298 die_nest_count--; 299 if (!die_nest_count) 300 /* Nest count reaches zero, release the lock. */ 301 arch_spin_unlock(&die_lock); 302 raw_local_irq_restore(flags); 303 oops_exit(); 304 305 if (in_interrupt()) 306 panic("Fatal exception in interrupt"); 307 if (panic_on_oops) 308 panic("Fatal exception"); 309 if (signr) 310 do_exit(signr); 311 } 312 313 /* 314 * This function is protected against re-entrancy. 315 */ 316 void die(const char *str, struct pt_regs *regs, int err) 317 { 318 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE; 319 unsigned long flags = oops_begin(); 320 int sig = SIGSEGV; 321 322 if (!user_mode(regs)) 323 bug_type = report_bug(regs->ARM_pc, regs); 324 if (bug_type != BUG_TRAP_TYPE_NONE) 325 str = "Oops - BUG"; 326 327 if (__die(str, err, regs)) 328 sig = 0; 329 330 oops_end(flags, regs, sig); 331 } 332 333 void arm_notify_die(const char *str, struct pt_regs *regs, 334 struct siginfo *info, unsigned long err, unsigned long trap) 335 { 336 if (user_mode(regs)) { 337 current->thread.error_code = err; 338 current->thread.trap_no = trap; 339 340 force_sig_info(info->si_signo, info, current); 341 } else { 342 die(str, regs, err); 343 } 344 } 345 346 #ifdef CONFIG_GENERIC_BUG 347 348 int is_valid_bugaddr(unsigned long pc) 349 { 350 #ifdef CONFIG_THUMB2_KERNEL 351 u16 bkpt; 352 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE); 353 #else 354 u32 bkpt; 355 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE); 356 #endif 357 358 if (probe_kernel_address((unsigned *)pc, bkpt)) 359 return 0; 360 361 return bkpt == insn; 362 } 363 364 #endif 365 366 static LIST_HEAD(undef_hook); 367 static DEFINE_RAW_SPINLOCK(undef_lock); 368 369 void register_undef_hook(struct undef_hook *hook) 370 { 371 unsigned long flags; 372 373 raw_spin_lock_irqsave(&undef_lock, flags); 374 list_add(&hook->node, &undef_hook); 375 raw_spin_unlock_irqrestore(&undef_lock, flags); 376 } 377 378 void unregister_undef_hook(struct undef_hook *hook) 379 { 380 unsigned long flags; 381 382 raw_spin_lock_irqsave(&undef_lock, flags); 383 list_del(&hook->node); 384 raw_spin_unlock_irqrestore(&undef_lock, flags); 385 } 386 387 static int call_undef_hook(struct pt_regs *regs, unsigned int instr) 388 { 389 struct undef_hook *hook; 390 unsigned long flags; 391 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL; 392 393 raw_spin_lock_irqsave(&undef_lock, flags); 394 list_for_each_entry(hook, &undef_hook, node) 395 if ((instr & hook->instr_mask) == hook->instr_val && 396 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val) 397 fn = hook->fn; 398 raw_spin_unlock_irqrestore(&undef_lock, flags); 399 400 return fn ? fn(regs, instr) : 1; 401 } 402 403 asmlinkage void __exception do_undefinstr(struct pt_regs *regs) 404 { 405 unsigned int instr; 406 siginfo_t info; 407 void __user *pc; 408 409 pc = (void __user *)instruction_pointer(regs); 410 411 if (processor_mode(regs) == SVC_MODE) { 412 #ifdef CONFIG_THUMB2_KERNEL 413 if (thumb_mode(regs)) { 414 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]); 415 if (is_wide_instruction(instr)) { 416 u16 inst2; 417 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]); 418 instr = __opcode_thumb32_compose(instr, inst2); 419 } 420 } else 421 #endif 422 instr = __mem_to_opcode_arm(*(u32 *) pc); 423 } else if (thumb_mode(regs)) { 424 if (get_user(instr, (u16 __user *)pc)) 425 goto die_sig; 426 instr = __mem_to_opcode_thumb16(instr); 427 if (is_wide_instruction(instr)) { 428 unsigned int instr2; 429 if (get_user(instr2, (u16 __user *)pc+1)) 430 goto die_sig; 431 instr2 = __mem_to_opcode_thumb16(instr2); 432 instr = __opcode_thumb32_compose(instr, instr2); 433 } 434 } else { 435 if (get_user(instr, (u32 __user *)pc)) 436 goto die_sig; 437 instr = __mem_to_opcode_arm(instr); 438 } 439 440 if (call_undef_hook(regs, instr) == 0) 441 return; 442 443 die_sig: 444 #ifdef CONFIG_DEBUG_USER 445 if (user_debug & UDBG_UNDEFINED) { 446 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n", 447 current->comm, task_pid_nr(current), pc); 448 dump_instr(KERN_INFO, regs); 449 } 450 #endif 451 452 info.si_signo = SIGILL; 453 info.si_errno = 0; 454 info.si_code = ILL_ILLOPC; 455 info.si_addr = pc; 456 457 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6); 458 } 459 460 asmlinkage void do_unexp_fiq (struct pt_regs *regs) 461 { 462 printk("Hmm. Unexpected FIQ received, but trying to continue\n"); 463 printk("You may have a hardware problem...\n"); 464 } 465 466 /* 467 * bad_mode handles the impossible case in the vectors. If you see one of 468 * these, then it's extremely serious, and could mean you have buggy hardware. 469 * It never returns, and never tries to sync. We hope that we can at least 470 * dump out some state information... 471 */ 472 asmlinkage void bad_mode(struct pt_regs *regs, int reason) 473 { 474 console_verbose(); 475 476 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]); 477 478 die("Oops - bad mode", regs, 0); 479 local_irq_disable(); 480 panic("bad mode"); 481 } 482 483 static int bad_syscall(int n, struct pt_regs *regs) 484 { 485 struct thread_info *thread = current_thread_info(); 486 siginfo_t info; 487 488 if ((current->personality & PER_MASK) != PER_LINUX && 489 thread->exec_domain->handler) { 490 thread->exec_domain->handler(n, regs); 491 return regs->ARM_r0; 492 } 493 494 #ifdef CONFIG_DEBUG_USER 495 if (user_debug & UDBG_SYSCALL) { 496 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n", 497 task_pid_nr(current), current->comm, n); 498 dump_instr(KERN_ERR, regs); 499 } 500 #endif 501 502 info.si_signo = SIGILL; 503 info.si_errno = 0; 504 info.si_code = ILL_ILLTRP; 505 info.si_addr = (void __user *)instruction_pointer(regs) - 506 (thumb_mode(regs) ? 2 : 4); 507 508 arm_notify_die("Oops - bad syscall", regs, &info, n, 0); 509 510 return regs->ARM_r0; 511 } 512 513 static long do_cache_op_restart(struct restart_block *); 514 515 static inline int 516 __do_cache_op(unsigned long start, unsigned long end) 517 { 518 int ret; 519 520 do { 521 unsigned long chunk = min(PAGE_SIZE, end - start); 522 523 if (signal_pending(current)) { 524 struct thread_info *ti = current_thread_info(); 525 526 ti->restart_block = (struct restart_block) { 527 .fn = do_cache_op_restart, 528 }; 529 530 ti->arm_restart_block = (struct arm_restart_block) { 531 { 532 .cache = { 533 .start = start, 534 .end = end, 535 }, 536 }, 537 }; 538 539 return -ERESTART_RESTARTBLOCK; 540 } 541 542 ret = flush_cache_user_range(start, start + chunk); 543 if (ret) 544 return ret; 545 546 cond_resched(); 547 start += chunk; 548 } while (start < end); 549 550 return 0; 551 } 552 553 static long do_cache_op_restart(struct restart_block *unused) 554 { 555 struct arm_restart_block *restart_block; 556 557 restart_block = ¤t_thread_info()->arm_restart_block; 558 return __do_cache_op(restart_block->cache.start, 559 restart_block->cache.end); 560 } 561 562 static inline int 563 do_cache_op(unsigned long start, unsigned long end, int flags) 564 { 565 if (end < start || flags) 566 return -EINVAL; 567 568 if (!access_ok(VERIFY_READ, start, end - start)) 569 return -EFAULT; 570 571 return __do_cache_op(start, end); 572 } 573 574 /* 575 * Handle all unrecognised system calls. 576 * 0x9f0000 - 0x9fffff are some more esoteric system calls 577 */ 578 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE) 579 asmlinkage int arm_syscall(int no, struct pt_regs *regs) 580 { 581 struct thread_info *thread = current_thread_info(); 582 siginfo_t info; 583 584 if ((no >> 16) != (__ARM_NR_BASE>> 16)) 585 return bad_syscall(no, regs); 586 587 switch (no & 0xffff) { 588 case 0: /* branch through 0 */ 589 info.si_signo = SIGSEGV; 590 info.si_errno = 0; 591 info.si_code = SEGV_MAPERR; 592 info.si_addr = NULL; 593 594 arm_notify_die("branch through zero", regs, &info, 0, 0); 595 return 0; 596 597 case NR(breakpoint): /* SWI BREAK_POINT */ 598 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4; 599 ptrace_break(current, regs); 600 return regs->ARM_r0; 601 602 /* 603 * Flush a region from virtual address 'r0' to virtual address 'r1' 604 * _exclusive_. There is no alignment requirement on either address; 605 * user space does not need to know the hardware cache layout. 606 * 607 * r2 contains flags. It should ALWAYS be passed as ZERO until it 608 * is defined to be something else. For now we ignore it, but may 609 * the fires of hell burn in your belly if you break this rule. ;) 610 * 611 * (at a later date, we may want to allow this call to not flush 612 * various aspects of the cache. Passing '0' will guarantee that 613 * everything necessary gets flushed to maintain consistency in 614 * the specified region). 615 */ 616 case NR(cacheflush): 617 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2); 618 619 case NR(usr26): 620 if (!(elf_hwcap & HWCAP_26BIT)) 621 break; 622 regs->ARM_cpsr &= ~MODE32_BIT; 623 return regs->ARM_r0; 624 625 case NR(usr32): 626 if (!(elf_hwcap & HWCAP_26BIT)) 627 break; 628 regs->ARM_cpsr |= MODE32_BIT; 629 return regs->ARM_r0; 630 631 case NR(set_tls): 632 thread->tp_value[0] = regs->ARM_r0; 633 if (tls_emu) 634 return 0; 635 if (has_tls_reg) { 636 asm ("mcr p15, 0, %0, c13, c0, 3" 637 : : "r" (regs->ARM_r0)); 638 } else { 639 /* 640 * User space must never try to access this directly. 641 * Expect your app to break eventually if you do so. 642 * The user helper at 0xffff0fe0 must be used instead. 643 * (see entry-armv.S for details) 644 */ 645 *((unsigned int *)0xffff0ff0) = regs->ARM_r0; 646 } 647 return 0; 648 649 #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG 650 /* 651 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space. 652 * Return zero in r0 if *MEM was changed or non-zero if no exchange 653 * happened. Also set the user C flag accordingly. 654 * If access permissions have to be fixed up then non-zero is 655 * returned and the operation has to be re-attempted. 656 * 657 * *NOTE*: This is a ghost syscall private to the kernel. Only the 658 * __kuser_cmpxchg code in entry-armv.S should be aware of its 659 * existence. Don't ever use this from user code. 660 */ 661 case NR(cmpxchg): 662 for (;;) { 663 extern void do_DataAbort(unsigned long addr, unsigned int fsr, 664 struct pt_regs *regs); 665 unsigned long val; 666 unsigned long addr = regs->ARM_r2; 667 struct mm_struct *mm = current->mm; 668 pgd_t *pgd; pmd_t *pmd; pte_t *pte; 669 spinlock_t *ptl; 670 671 regs->ARM_cpsr &= ~PSR_C_BIT; 672 down_read(&mm->mmap_sem); 673 pgd = pgd_offset(mm, addr); 674 if (!pgd_present(*pgd)) 675 goto bad_access; 676 pmd = pmd_offset(pgd, addr); 677 if (!pmd_present(*pmd)) 678 goto bad_access; 679 pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 680 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) { 681 pte_unmap_unlock(pte, ptl); 682 goto bad_access; 683 } 684 val = *(unsigned long *)addr; 685 val -= regs->ARM_r0; 686 if (val == 0) { 687 *(unsigned long *)addr = regs->ARM_r1; 688 regs->ARM_cpsr |= PSR_C_BIT; 689 } 690 pte_unmap_unlock(pte, ptl); 691 up_read(&mm->mmap_sem); 692 return val; 693 694 bad_access: 695 up_read(&mm->mmap_sem); 696 /* simulate a write access fault */ 697 do_DataAbort(addr, 15 + (1 << 11), regs); 698 } 699 #endif 700 701 default: 702 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS 703 if not implemented, rather than raising SIGILL. This 704 way the calling program can gracefully determine whether 705 a feature is supported. */ 706 if ((no & 0xffff) <= 0x7ff) 707 return -ENOSYS; 708 break; 709 } 710 #ifdef CONFIG_DEBUG_USER 711 /* 712 * experience shows that these seem to indicate that 713 * something catastrophic has happened 714 */ 715 if (user_debug & UDBG_SYSCALL) { 716 printk("[%d] %s: arm syscall %d\n", 717 task_pid_nr(current), current->comm, no); 718 dump_instr("", regs); 719 if (user_mode(regs)) { 720 __show_regs(regs); 721 c_backtrace(regs->ARM_fp, processor_mode(regs)); 722 } 723 } 724 #endif 725 info.si_signo = SIGILL; 726 info.si_errno = 0; 727 info.si_code = ILL_ILLTRP; 728 info.si_addr = (void __user *)instruction_pointer(regs) - 729 (thumb_mode(regs) ? 2 : 4); 730 731 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0); 732 return 0; 733 } 734 735 #ifdef CONFIG_TLS_REG_EMUL 736 737 /* 738 * We might be running on an ARMv6+ processor which should have the TLS 739 * register but for some reason we can't use it, or maybe an SMP system 740 * using a pre-ARMv6 processor (there are apparently a few prototypes like 741 * that in existence) and therefore access to that register must be 742 * emulated. 743 */ 744 745 static int get_tp_trap(struct pt_regs *regs, unsigned int instr) 746 { 747 int reg = (instr >> 12) & 15; 748 if (reg == 15) 749 return 1; 750 regs->uregs[reg] = current_thread_info()->tp_value[0]; 751 regs->ARM_pc += 4; 752 return 0; 753 } 754 755 static struct undef_hook arm_mrc_hook = { 756 .instr_mask = 0x0fff0fff, 757 .instr_val = 0x0e1d0f70, 758 .cpsr_mask = PSR_T_BIT, 759 .cpsr_val = 0, 760 .fn = get_tp_trap, 761 }; 762 763 static int __init arm_mrc_hook_init(void) 764 { 765 register_undef_hook(&arm_mrc_hook); 766 return 0; 767 } 768 769 late_initcall(arm_mrc_hook_init); 770 771 #endif 772 773 void __bad_xchg(volatile void *ptr, int size) 774 { 775 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n", 776 __builtin_return_address(0), ptr, size); 777 BUG(); 778 } 779 EXPORT_SYMBOL(__bad_xchg); 780 781 /* 782 * A data abort trap was taken, but we did not handle the instruction. 783 * Try to abort the user program, or panic if it was the kernel. 784 */ 785 asmlinkage void 786 baddataabort(int code, unsigned long instr, struct pt_regs *regs) 787 { 788 unsigned long addr = instruction_pointer(regs); 789 siginfo_t info; 790 791 #ifdef CONFIG_DEBUG_USER 792 if (user_debug & UDBG_BADABORT) { 793 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n", 794 task_pid_nr(current), current->comm, code, instr); 795 dump_instr(KERN_ERR, regs); 796 show_pte(current->mm, addr); 797 } 798 #endif 799 800 info.si_signo = SIGILL; 801 info.si_errno = 0; 802 info.si_code = ILL_ILLOPC; 803 info.si_addr = (void __user *)addr; 804 805 arm_notify_die("unknown data abort code", regs, &info, instr, 0); 806 } 807 808 void __readwrite_bug(const char *fn) 809 { 810 printk("%s called, but not implemented\n", fn); 811 BUG(); 812 } 813 EXPORT_SYMBOL(__readwrite_bug); 814 815 void __pte_error(const char *file, int line, pte_t pte) 816 { 817 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte)); 818 } 819 820 void __pmd_error(const char *file, int line, pmd_t pmd) 821 { 822 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd)); 823 } 824 825 void __pgd_error(const char *file, int line, pgd_t pgd) 826 { 827 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd)); 828 } 829 830 asmlinkage void __div0(void) 831 { 832 printk("Division by zero in kernel.\n"); 833 dump_stack(); 834 } 835 EXPORT_SYMBOL(__div0); 836 837 void abort(void) 838 { 839 BUG(); 840 841 /* if that doesn't kill us, halt */ 842 panic("Oops failed to kill thread"); 843 } 844 EXPORT_SYMBOL(abort); 845 846 void __init trap_init(void) 847 { 848 return; 849 } 850 851 #ifdef CONFIG_KUSER_HELPERS 852 static void __init kuser_init(void *vectors) 853 { 854 extern char __kuser_helper_start[], __kuser_helper_end[]; 855 int kuser_sz = __kuser_helper_end - __kuser_helper_start; 856 857 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz); 858 859 /* 860 * vectors + 0xfe0 = __kuser_get_tls 861 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8 862 */ 863 if (tls_emu || has_tls_reg) 864 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4); 865 } 866 #else 867 static inline void __init kuser_init(void *vectors) 868 { 869 } 870 #endif 871 872 void __init early_trap_init(void *vectors_base) 873 { 874 #ifndef CONFIG_CPU_V7M 875 unsigned long vectors = (unsigned long)vectors_base; 876 extern char __stubs_start[], __stubs_end[]; 877 extern char __vectors_start[], __vectors_end[]; 878 unsigned i; 879 880 vectors_page = vectors_base; 881 882 /* 883 * Poison the vectors page with an undefined instruction. This 884 * instruction is chosen to be undefined for both ARM and Thumb 885 * ISAs. The Thumb version is an undefined instruction with a 886 * branch back to the undefined instruction. 887 */ 888 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++) 889 ((u32 *)vectors_base)[i] = 0xe7fddef1; 890 891 /* 892 * Copy the vectors, stubs and kuser helpers (in entry-armv.S) 893 * into the vector page, mapped at 0xffff0000, and ensure these 894 * are visible to the instruction stream. 895 */ 896 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start); 897 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start); 898 899 kuser_init(vectors_base); 900 901 flush_icache_range(vectors, vectors + PAGE_SIZE * 2); 902 modify_domain(DOMAIN_USER, DOMAIN_CLIENT); 903 #else /* ifndef CONFIG_CPU_V7M */ 904 /* 905 * on V7-M there is no need to copy the vector table to a dedicated 906 * memory area. The address is configurable and so a table in the kernel 907 * image can be used. 908 */ 909 #endif 910 } 911