text: /*
   *  linux/arch/arm/kernel/traps.c
   *
   *  Copyright (C) 1995-2009 Russell King
   *  Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   *  'traps.c' handles hardware exceptions after we have saved some state in
   *  'linux/arch/arm/lib/traps.S'.  Mostly a debugging aid, but will probably
   *  kill the offending process.
   */
  #include <linux/signal.h>
  #include <linux/personality.h>
  #include <linux/kallsyms.h>
  #include <linux/spinlock.h>
  #include <linux/uaccess.h>
  #include <linux/hardirq.h>
  #include <linux/kdebug.h>
  #include <linux/kprobes.h>
  #include <linux/module.h>
  #include <linux/kexec.h>
  #include <linux/bug.h>
  #include <linux/delay.h>
  #include <linux/init.h>
  #include <linux/sched.h>
  #include <linux/irq.h>
  
  #include <linux/atomic.h>
  #include <asm/cacheflush.h>
  #include <asm/exception.h>
  #include <asm/unistd.h>
  #include <asm/traps.h>
  #include <asm/ptrace.h>
  #include <asm/unwind.h>
  #include <asm/tls.h>
  #include <asm/system_misc.h>
  #include <asm/opcodes.h>
  
  
  static const char *handler[]= {
  	"prefetch abort",
  	"data abort",
  	"address exception",
  	"interrupt",
  	"undefined instruction",
  };
  
  void *vectors_page;
  
  #ifdef CONFIG_DEBUG_USER
  unsigned int user_debug;
  
  static int __init user_debug_setup(char *str)
  {
  	get_option(&str, &user_debug);
  	return 1;
  }
  __setup("user_debug=", user_debug_setup);
  #endif
  
  static void dump_mem(const char *, const char *, unsigned long, unsigned long);
  
  void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
  {
  #ifdef CONFIG_KALLSYMS
  	printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
  #else
  	printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
  #endif
  
  	if (in_exception_text(where))
  		dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
  }
  
  #ifndef CONFIG_ARM_UNWIND
  /*
   * Stack pointers should always be within the kernels view of
   * physical memory.  If it is not there, then we can't dump
   * out any information relating to the stack.
   */
  static int verify_stack(unsigned long sp)
  {
  	if (sp < PAGE_OFFSET ||
  	    (sp > (unsigned long)high_memory && high_memory != NULL))
  		return -EFAULT;
  
  	return 0;
  }
  #endif
  
  /*
   * Dump out the contents of some memory nicely...
   */
  static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
  		     unsigned long top)
  {
  	unsigned long first;
  	mm_segment_t fs;
  	int i;
  
  	/*
  	 * We need to switch to kernel mode so that we can use __get_user
  	 * to safely read from kernel space.  Note that we now dump the
  	 * code first, just in case the backtrace kills us.
  	 */
  	fs = get_fs();
  	set_fs(KERNEL_DS);
  
  	printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
  
  	for (first = bottom & ~31; first < top; first += 32) {
  		unsigned long p;
  		char str[sizeof(" 12345678") * 8 + 1];
  
  		memset(str, ' ', sizeof(str));
  		str[sizeof(str) - 1] = '\0';
  
  		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
  			if (p >= bottom && p < top) {
  				unsigned long val;
  				if (__get_user(val, (unsigned long *)p) == 0)
  					sprintf(str + i * 9, " %08lx", val);
  				else
  					sprintf(str + i * 9, " ????????");
  			}
  		}
  		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
  	}
  
  	set_fs(fs);
  }
  
  static void __dump_instr(const char *lvl, struct pt_regs *regs)
  {
  	unsigned long addr = instruction_pointer(regs);
  	const int thumb = thumb_mode(regs);
  	const int width = thumb ? 4 : 8;
  	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
  	int i;
  
  	/*
  	 * Note that we now dump the code first, just in case the backtrace
  	 * kills us.
  	 */
  
  	for (i = -4; i < 1 + !!thumb; i++) {
  		unsigned int val, bad;
  
  		if (thumb)
  			bad = get_user(val, &((u16 *)addr)[i]);
  		else
  			bad = get_user(val, &((u32 *)addr)[i]);
  
  		if (!bad)
  			p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
  					width, val);
  		else {
  			p += sprintf(p, "bad PC value");
  			break;
  		}
  	}
  	printk("%sCode: %s\n", lvl, str);
  }
  
  static void dump_instr(const char *lvl, struct pt_regs *regs)
  {
  	mm_segment_t fs;
  
  	if (!user_mode(regs)) {
  		fs = get_fs();
  		set_fs(KERNEL_DS);
  		__dump_instr(lvl, regs);
  		set_fs(fs);
  	} else {
  		__dump_instr(lvl, regs);
  	}
  }
  
  #ifdef CONFIG_ARM_UNWIND
  static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
  {
  	unwind_backtrace(regs, tsk);
  }
  #else
  static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
  {
  	unsigned int fp, mode;
  	int ok = 1;
  
  	printk("Backtrace: ");
  
  	if (!tsk)
  		tsk = current;
  
  	if (regs) {
  		fp = frame_pointer(regs);
  		mode = processor_mode(regs);
  	} else if (tsk != current) {
  		fp = thread_saved_fp(tsk);
  		mode = 0x10;
  	} else {
  		asm("mov %0, fp" : "=r" (fp) : : "cc");
  		mode = 0x10;
  	}
  
  	if (!fp) {
  		printk("no frame pointer");
  		ok = 0;
  	} else if (verify_stack(fp)) {
  		printk("invalid frame pointer 0x%08x", fp);
  		ok = 0;
  	} else if (fp < (unsigned long)end_of_stack(tsk))
  		printk("frame pointer underflow");
  	printk("\n");
  
  	if (ok)
  		c_backtrace(fp, mode);
  }
  #endif
  
  void show_stack(struct task_struct *tsk, unsigned long *sp)
  {
  	dump_backtrace(NULL, tsk);
  	barrier();
  }
  
  #ifdef CONFIG_PREEMPT
  #define S_PREEMPT " PREEMPT"
  #else
  #define S_PREEMPT ""
  #endif
  #ifdef CONFIG_SMP
  #define S_SMP " SMP"
  #else
  #define S_SMP ""
  #endif
  #ifdef CONFIG_THUMB2_KERNEL
  #define S_ISA " THUMB2"
  #else
  #define S_ISA " ARM"
  #endif
  
  static int __die(const char *str, int err, struct pt_regs *regs)
  {
  	struct task_struct *tsk = current;
  	static int die_counter;
  	int ret;
  
  	printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
  	       S_ISA "\n", str, err, ++die_counter);
  
  	/* trap and error numbers are mostly meaningless on ARM */
  	ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
  	if (ret == NOTIFY_STOP)
  		return 1;
  
  	print_modules();
  	__show_regs(regs);
  	printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
  		TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
  
  	if (!user_mode(regs) || in_interrupt()) {
  		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
  			 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
  		dump_backtrace(regs, tsk);
  		dump_instr(KERN_EMERG, regs);
  	}
  
  	return 0;
  }
  
  static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
  static int die_owner = -1;
  static unsigned int die_nest_count;
  
  static unsigned long oops_begin(void)
  {
  	int cpu;
  	unsigned long flags;
  
  	oops_enter();
  
  	/* racy, but better than risking deadlock. */
  	raw_local_irq_save(flags);
  	cpu = smp_processor_id();
  	if (!arch_spin_trylock(&die_lock)) {
  		if (cpu == die_owner)
  			/* nested oops. should stop eventually */;
  		else
  			arch_spin_lock(&die_lock);
  	}
  	die_nest_count++;
  	die_owner = cpu;
  	console_verbose();
  	bust_spinlocks(1);
  	return flags;
  }
  
  static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
  {
  	if (regs && kexec_should_crash(current))
  		crash_kexec(regs);
  
  	bust_spinlocks(0);
  	die_owner = -1;
  	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
  	die_nest_count--;
  	if (!die_nest_count)
  		/* Nest count reaches zero, release the lock. */
  		arch_spin_unlock(&die_lock);
  	raw_local_irq_restore(flags);
  	oops_exit();
  
  	if (in_interrupt())
  		panic("Fatal exception in interrupt");
  	if (panic_on_oops)
  		panic("Fatal exception");
  	if (signr)
  		do_exit(signr);
  }
  
  /*
   * This function is protected against re-entrancy.
   */
  void die(const char *str, struct pt_regs *regs, int err)
  {
  	enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
  	unsigned long flags = oops_begin();
  	int sig = SIGSEGV;
  
  	if (!user_mode(regs))
  		bug_type = report_bug(regs->ARM_pc, regs);
  	if (bug_type != BUG_TRAP_TYPE_NONE)
  		str = "Oops - BUG";
  
  	if (__die(str, err, regs))
  		sig = 0;
  
  	oops_end(flags, regs, sig);
  }
  
  void arm_notify_die(const char *str, struct pt_regs *regs,
  		struct siginfo *info, unsigned long err, unsigned long trap)
  {
  	if (user_mode(regs)) {
  		current->thread.error_code = err;
  		current->thread.trap_no = trap;
  
  		force_sig_info(info->si_signo, info, current);
  	} else {
  		die(str, regs, err);
  	}
  }
  
  #ifdef CONFIG_GENERIC_BUG
  
  int is_valid_bugaddr(unsigned long pc)
  {
  #ifdef CONFIG_THUMB2_KERNEL
  	u16 bkpt;
  	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
  #else
  	u32 bkpt;
  	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
  #endif
  
  	if (probe_kernel_address((unsigned *)pc, bkpt))
  		return 0;
  
  	return bkpt == insn;
  }
  
  #endif
  
  static LIST_HEAD(undef_hook);
  static DEFINE_RAW_SPINLOCK(undef_lock);
  
  void register_undef_hook(struct undef_hook *hook)
  {
  	unsigned long flags;
  
  	raw_spin_lock_irqsave(&undef_lock, flags);
  	list_add(&hook->node, &undef_hook);
  	raw_spin_unlock_irqrestore(&undef_lock, flags);
  }
  
  void unregister_undef_hook(struct undef_hook *hook)
  {
  	unsigned long flags;
  
  	raw_spin_lock_irqsave(&undef_lock, flags);
  	list_del(&hook->node);
  	raw_spin_unlock_irqrestore(&undef_lock, flags);
  }
  
  static nokprobe_inline
  int call_undef_hook(struct pt_regs *regs, unsigned int instr)
  {
  	struct undef_hook *hook;
  	unsigned long flags;
  	int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
  
  	raw_spin_lock_irqsave(&undef_lock, flags);
  	list_for_each_entry(hook, &undef_hook, node)
  		if ((instr & hook->instr_mask) == hook->instr_val &&
  		    (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
  			fn = hook->fn;
  	raw_spin_unlock_irqrestore(&undef_lock, flags);
  
  	return fn ? fn(regs, instr) : 1;
  }
  
  asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
  {
  	unsigned int instr;
  	siginfo_t info;
  	void __user *pc;
  
  	pc = (void __user *)instruction_pointer(regs);
  
  	if (processor_mode(regs) == SVC_MODE) {
  #ifdef CONFIG_THUMB2_KERNEL
  		if (thumb_mode(regs)) {
  			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
  			if (is_wide_instruction(instr)) {
  				u16 inst2;
  				inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
  				instr = __opcode_thumb32_compose(instr, inst2);
  			}
  		} else
  #endif
  			instr = __mem_to_opcode_arm(*(u32 *) pc);
  	} else if (thumb_mode(regs)) {
  		if (get_user(instr, (u16 __user *)pc))
  			goto die_sig;
  		instr = __mem_to_opcode_thumb16(instr);
  		if (is_wide_instruction(instr)) {
  			unsigned int instr2;
  			if (get_user(instr2, (u16 __user *)pc+1))
  				goto die_sig;
  			instr2 = __mem_to_opcode_thumb16(instr2);
  			instr = __opcode_thumb32_compose(instr, instr2);
  		}
  	} else {
  		if (get_user(instr, (u32 __user *)pc))
  			goto die_sig;
  		instr = __mem_to_opcode_arm(instr);
  	}
  
  	if (call_undef_hook(regs, instr) == 0)
  		return;
  
  die_sig:
  #ifdef CONFIG_DEBUG_USER
  	if (user_debug & UDBG_UNDEFINED) {
  		printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
  			current->comm, task_pid_nr(current), pc);
  		__show_regs(regs);
  		dump_instr(KERN_INFO, regs);
  	}
  #endif
  
  	info.si_signo = SIGILL;
  	info.si_errno = 0;
  	info.si_code  = ILL_ILLOPC;
  	info.si_addr  = pc;
  
  	arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
  }
  NOKPROBE_SYMBOL(do_undefinstr)
  
  /*
   * Handle FIQ similarly to NMI on x86 systems.
   *
   * The runtime environment for NMIs is extremely restrictive
   * (NMIs can pre-empt critical sections meaning almost all locking is
   * forbidden) meaning this default FIQ handling must only be used in
   * circumstances where non-maskability improves robustness, such as
   * watchdog or debug logic.
   *
   * This handler is not appropriate for general purpose use in drivers
   * platform code and can be overrideen using set_fiq_handler.
   */
  asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
  {
  	struct pt_regs *old_regs = set_irq_regs(regs);
  
  	nmi_enter();
  
  	/* nop. FIQ handlers for special arch/arm features can be added here. */
  
  	nmi_exit();
  
  	set_irq_regs(old_regs);
  }
  
  /*
   * bad_mode handles the impossible case in the vectors.  If you see one of
   * these, then it's extremely serious, and could mean you have buggy hardware.
   * It never returns, and never tries to sync.  We hope that we can at least
   * dump out some state information...
   */
  asmlinkage void bad_mode(struct pt_regs *regs, int reason)
  {
  	console_verbose();
  
  	printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
  
  	die("Oops - bad mode", regs, 0);
  	local_irq_disable();
  	panic("bad mode");
  }
  
  static int bad_syscall(int n, struct pt_regs *regs)
  {
  	struct thread_info *thread = current_thread_info();
  	siginfo_t info;
  
  	if ((current->personality & PER_MASK) != PER_LINUX &&
  	    thread->exec_domain->handler) {
  		thread->exec_domain->handler(n, regs);
  		return regs->ARM_r0;
  	}
  
  #ifdef CONFIG_DEBUG_USER
  	if (user_debug & UDBG_SYSCALL) {
  		printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
  			task_pid_nr(current), current->comm, n);
  		dump_instr(KERN_ERR, regs);
  	}
  #endif
  
  	info.si_signo = SIGILL;
  	info.si_errno = 0;
  	info.si_code  = ILL_ILLTRP;
  	info.si_addr  = (void __user *)instruction_pointer(regs) -
  			 (thumb_mode(regs) ? 2 : 4);
  
  	arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
  
  	return regs->ARM_r0;
  }
  
  static inline int
  __do_cache_op(unsigned long start, unsigned long end)
  {
  	int ret;
  
  	do {
  		unsigned long chunk = min(PAGE_SIZE, end - start);
  
  		if (fatal_signal_pending(current))
  			return 0;
  
  		ret = flush_cache_user_range(start, start + chunk);
  		if (ret)
  			return ret;
  
  		cond_resched();
  		start += chunk;
  	} while (start < end);
  
  	return 0;
  }
  
  static inline int
  do_cache_op(unsigned long start, unsigned long end, int flags)
  {
  	if (end < start || flags)
  		return -EINVAL;
  
  	if (!access_ok(VERIFY_READ, start, end - start))
  		return -EFAULT;
  
  	return __do_cache_op(start, end);
  }
  
  /*
   * Handle all unrecognised system calls.
   *  0x9f0000 - 0x9fffff are some more esoteric system calls
   */
  #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
  asmlinkage int arm_syscall(int no, struct pt_regs *regs)
  {
  	siginfo_t info;
  
  	if ((no >> 16) != (__ARM_NR_BASE>> 16))
  		return bad_syscall(no, regs);
  
  	switch (no & 0xffff) {
  	case 0: /* branch through 0 */
  		info.si_signo = SIGSEGV;
  		info.si_errno = 0;
  		info.si_code  = SEGV_MAPERR;
  		info.si_addr  = NULL;
  
  		arm_notify_die("branch through zero", regs, &info, 0, 0);
  		return 0;
  
  	case NR(breakpoint): /* SWI BREAK_POINT */
  		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
  		ptrace_break(current, regs);
  		return regs->ARM_r0;
  
  	/*
  	 * Flush a region from virtual address 'r0' to virtual address 'r1'
  	 * _exclusive_.  There is no alignment requirement on either address;
  	 * user space does not need to know the hardware cache layout.
  	 *
  	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
  	 * is defined to be something else.  For now we ignore it, but may
  	 * the fires of hell burn in your belly if you break this rule. ;)
  	 *
  	 * (at a later date, we may want to allow this call to not flush
  	 * various aspects of the cache.  Passing '0' will guarantee that
  	 * everything necessary gets flushed to maintain consistency in
  	 * the specified region).
  	 */
  	case NR(cacheflush):
  		return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
  
  	case NR(usr26):
  		if (!(elf_hwcap & HWCAP_26BIT))
  			break;
  		regs->ARM_cpsr &= ~MODE32_BIT;
  		return regs->ARM_r0;
  
  	case NR(usr32):
  		if (!(elf_hwcap & HWCAP_26BIT))
  			break;
  		regs->ARM_cpsr |= MODE32_BIT;
  		return regs->ARM_r0;
  
  	case NR(set_tls):
  		set_tls(regs->ARM_r0);
  		return 0;
  
  #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
  	/*
  	 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
  	 * Return zero in r0 if *MEM was changed or non-zero if no exchange
  	 * happened.  Also set the user C flag accordingly.
  	 * If access permissions have to be fixed up then non-zero is
  	 * returned and the operation has to be re-attempted.
  	 *
  	 * *NOTE*: This is a ghost syscall private to the kernel.  Only the
  	 * __kuser_cmpxchg code in entry-armv.S should be aware of its
  	 * existence.  Don't ever use this from user code.
  	 */
  	case NR(cmpxchg):
  	for (;;) {
  		extern void do_DataAbort(unsigned long addr, unsigned int fsr,
  					 struct pt_regs *regs);
  		unsigned long val;
  		unsigned long addr = regs->ARM_r2;
  		struct mm_struct *mm = current->mm;
  		pgd_t *pgd; pmd_t *pmd; pte_t *pte;
  		spinlock_t *ptl;
  
  		regs->ARM_cpsr &= ~PSR_C_BIT;
  		down_read(&mm->mmap_sem);
  		pgd = pgd_offset(mm, addr);
  		if (!pgd_present(*pgd))
  			goto bad_access;
  		pmd = pmd_offset(pgd, addr);
  		if (!pmd_present(*pmd))
  			goto bad_access;
  		pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
  		if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
  			pte_unmap_unlock(pte, ptl);
  			goto bad_access;
  		}
  		val = *(unsigned long *)addr;
  		val -= regs->ARM_r0;
  		if (val == 0) {
  			*(unsigned long *)addr = regs->ARM_r1;
  			regs->ARM_cpsr |= PSR_C_BIT;
  		}
  		pte_unmap_unlock(pte, ptl);
  		up_read(&mm->mmap_sem);
  		return val;
  
  		bad_access:
  		up_read(&mm->mmap_sem);
  		/* simulate a write access fault */
  		do_DataAbort(addr, 15 + (1 << 11), regs);
  	}
  #endif
  
  	default:
  		/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
  		   if not implemented, rather than raising SIGILL.  This
  		   way the calling program can gracefully determine whether
  		   a feature is supported.  */
  		if ((no & 0xffff) <= 0x7ff)
  			return -ENOSYS;
  		break;
  	}
  #ifdef CONFIG_DEBUG_USER
  	/*
  	 * experience shows that these seem to indicate that
  	 * something catastrophic has happened
  	 */
  	if (user_debug & UDBG_SYSCALL) {
  		printk("[%d] %s: arm syscall %d\n",
  		       task_pid_nr(current), current->comm, no);
  		dump_instr("", regs);
  		if (user_mode(regs)) {
  			__show_regs(regs);
  			c_backtrace(frame_pointer(regs), processor_mode(regs));
  		}
  	}
  #endif
  	info.si_signo = SIGILL;
  	info.si_errno = 0;
  	info.si_code  = ILL_ILLTRP;
  	info.si_addr  = (void __user *)instruction_pointer(regs) -
  			 (thumb_mode(regs) ? 2 : 4);
  
  	arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
  	return 0;
  }
  
  #ifdef CONFIG_TLS_REG_EMUL
  
  /*
   * We might be running on an ARMv6+ processor which should have the TLS
   * register but for some reason we can't use it, or maybe an SMP system
   * using a pre-ARMv6 processor (there are apparently a few prototypes like
   * that in existence) and therefore access to that register must be
   * emulated.
   */
  
  static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
  {
  	int reg = (instr >> 12) & 15;
  	if (reg == 15)
  		return 1;
  	regs->uregs[reg] = current_thread_info()->tp_value[0];
  	regs->ARM_pc += 4;
  	return 0;
  }
  
  static struct undef_hook arm_mrc_hook = {
  	.instr_mask	= 0x0fff0fff,
  	.instr_val	= 0x0e1d0f70,
  	.cpsr_mask	= PSR_T_BIT,
  	.cpsr_val	= 0,
  	.fn		= get_tp_trap,
  };
  
  static int __init arm_mrc_hook_init(void)
  {
  	register_undef_hook(&arm_mrc_hook);
  	return 0;
  }
  
  late_initcall(arm_mrc_hook_init);
  
  #endif
  
  void __bad_xchg(volatile void *ptr, int size)
  {
  	printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
  		__builtin_return_address(0), ptr, size);
  	BUG();
  }
  EXPORT_SYMBOL(__bad_xchg);
  
  /*
   * A data abort trap was taken, but we did not handle the instruction.
   * Try to abort the user program, or panic if it was the kernel.
   */
  asmlinkage void
  baddataabort(int code, unsigned long instr, struct pt_regs *regs)
  {
  	unsigned long addr = instruction_pointer(regs);
  	siginfo_t info;
  
  #ifdef CONFIG_DEBUG_USER
  	if (user_debug & UDBG_BADABORT) {
  		printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
  			task_pid_nr(current), current->comm, code, instr);
  		dump_instr(KERN_ERR, regs);
  		show_pte(current->mm, addr);
  	}
  #endif
  
  	info.si_signo = SIGILL;
  	info.si_errno = 0;
  	info.si_code  = ILL_ILLOPC;
  	info.si_addr  = (void __user *)addr;
  
  	arm_notify_die("unknown data abort code", regs, &info, instr, 0);
  }
  
  void __readwrite_bug(const char *fn)
  {
  	printk("%s called, but not implemented\n", fn);
  	BUG();
  }
  EXPORT_SYMBOL(__readwrite_bug);
  
  void __pte_error(const char *file, int line, pte_t pte)
  {
  	printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
  }
  
  void __pmd_error(const char *file, int line, pmd_t pmd)
  {
  	printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
  }
  
  void __pgd_error(const char *file, int line, pgd_t pgd)
  {
  	printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
  }
  
  asmlinkage void __div0(void)
  {
  	printk("Division by zero in kernel.\n");
  	dump_stack();
  }
  EXPORT_SYMBOL(__div0);
  
  void abort(void)
  {
  	BUG();
  
  	/* if that doesn't kill us, halt */
  	panic("Oops failed to kill thread");
  }
  EXPORT_SYMBOL(abort);
  
  void __init trap_init(void)
  {
  	return;
  }
  
  #ifdef CONFIG_KUSER_HELPERS
  static void __init kuser_init(void *vectors)
  {
  	extern char __kuser_helper_start[], __kuser_helper_end[];
  	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
  
  	memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
  
  	/*
  	 * vectors + 0xfe0 = __kuser_get_tls
  	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
  	 */
  	if (tls_emu || has_tls_reg)
  		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
  }
  #else
  static inline void __init kuser_init(void *vectors)
  {
  }
  #endif
  
  void __init early_trap_init(void *vectors_base)
  {
  #ifndef CONFIG_CPU_V7M
  	unsigned long vectors = (unsigned long)vectors_base;
  	extern char __stubs_start[], __stubs_end[];
  	extern char __vectors_start[], __vectors_end[];
  	unsigned i;
  
  	vectors_page = vectors_base;
  
  	/*
  	 * Poison the vectors page with an undefined instruction.  This
  	 * instruction is chosen to be undefined for both ARM and Thumb
  	 * ISAs.  The Thumb version is an undefined instruction with a
  	 * branch back to the undefined instruction.
  	 */
  	for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
  		((u32 *)vectors_base)[i] = 0xe7fddef1;
  
  	/*
  	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
  	 * into the vector page, mapped at 0xffff0000, and ensure these
  	 * are visible to the instruction stream.
  	 */
  	memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
  	memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
  
  	kuser_init(vectors_base);
  
  	flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
  #else /* ifndef CONFIG_CPU_V7M */
  	/*
  	 * on V7-M there is no need to copy the vector table to a dedicated
  	 * memory area. The address is configurable and so a table in the kernel
  	 * image can be used.
  	 */
  #endif
  }
  