arch/arm/kernel/traps.c

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