/*

   *  Copyright (C) 1991, 1992  Linus Torvalds

   *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs

   *
   *  Pentium III FXSR, SSE support
   *	Gareth Hughes <gareth@valinux.com>, May 2000
   */
  
  /*

   * Handle hardware traps and faults.

   */

  #include <linux/interrupt.h>
  #include <linux/kallsyms.h>
  #include <linux/spinlock.h>

  #include <linux/kprobes.h>
  #include <linux/uaccess.h>

  #include <linux/kdebug.h>

  #include <linux/kgdb.h>

  #include <linux/kernel.h>

  #include <linux/module.h>
  #include <linux/ptrace.h>

  #include <linux/string.h>

  #include <linux/delay.h>

  #include <linux/errno.h>

  #include <linux/kexec.h>
  #include <linux/sched.h>

  #include <linux/timer.h>

  #include <linux/init.h>

  #include <linux/bug.h>

  #include <linux/nmi.h>
  #include <linux/mm.h>

  #include <linux/smp.h>
  #include <linux/io.h>

  
  #ifdef CONFIG_EISA
  #include <linux/ioport.h>
  #include <linux/eisa.h>
  #endif
  
  #ifdef CONFIG_MCA
  #include <linux/mca.h>
  #endif

  #if defined(CONFIG_EDAC)
  #include <linux/edac.h>
  #endif

  #include <asm/kmemcheck.h>

  #include <asm/stacktrace.h>

  #include <asm/processor.h>

  #include <asm/debugreg.h>

  #include <linux/atomic.h>

  #include <asm/system.h>

  #include <asm/traps.h>

  #include <asm/desc.h>
  #include <asm/i387.h>

  #include <asm/mce.h>

  #include <asm/mach_traps.h>

  #ifdef CONFIG_X86_64

  #include <asm/x86_init.h>

  #include <asm/pgalloc.h>
  #include <asm/proto.h>

  #else

  #include <asm/processor-flags.h>

  #include <asm/setup.h>

  asmlinkage int system_call(void);

  /* Do we ignore FPU interrupts ? */

  char ignore_fpu_irq;

  
  /*
   * The IDT has to be page-aligned to simplify the Pentium

   * F0 0F bug workaround.

   */

  gate_desc idt_table[NR_VECTORS] __page_aligned_data = { { { { 0, 0 } } }, };

  #endif

  DECLARE_BITMAP(used_vectors, NR_VECTORS);
  EXPORT_SYMBOL_GPL(used_vectors);

  static inline void conditional_sti(struct pt_regs *regs)
  {
  	if (regs->flags & X86_EFLAGS_IF)
  		local_irq_enable();
  }

  static inline void preempt_conditional_sti(struct pt_regs *regs)
  {
  	inc_preempt_count();
  	if (regs->flags & X86_EFLAGS_IF)
  		local_irq_enable();
  }

  static inline void conditional_cli(struct pt_regs *regs)
  {
  	if (regs->flags & X86_EFLAGS_IF)
  		local_irq_disable();
  }

  static inline void preempt_conditional_cli(struct pt_regs *regs)
  {
  	if (regs->flags & X86_EFLAGS_IF)
  		local_irq_disable();
  	dec_preempt_count();
  }

  static void __kprobes

  do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,

  	long error_code, siginfo_t *info)

  {

  	struct task_struct *tsk = current;

  #ifdef CONFIG_X86_32

  	if (regs->flags & X86_VM_MASK) {

  		/*
  		 * traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
  		 * On nmi (interrupt 2), do_trap should not be called.
  		 */
  		if (trapnr < 6)

  			goto vm86_trap;
  		goto trap_signal;
  	}

  #endif

  	if (!user_mode(regs))

  		goto kernel_trap;

  #ifdef CONFIG_X86_32

  trap_signal:

  #endif

  	/*
  	 * We want error_code and trap_no set for userspace faults and
  	 * kernelspace faults which result in die(), but not
  	 * kernelspace faults which are fixed up.  die() gives the
  	 * process no chance to handle the signal and notice the
  	 * kernel fault information, so that won't result in polluting
  	 * the information about previously queued, but not yet
  	 * delivered, faults.  See also do_general_protection below.
  	 */
  	tsk->thread.error_code = error_code;
  	tsk->thread.trap_no = trapnr;

  #ifdef CONFIG_X86_64
  	if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
  	    printk_ratelimit()) {
  		printk(KERN_INFO
  		       "%s[%d] trap %s ip:%lx sp:%lx error:%lx",
  		       tsk->comm, tsk->pid, str,
  		       regs->ip, regs->sp, error_code);
  		print_vma_addr(" in ", regs->ip);
  		printk("
  ");
  	}
  #endif

  	if (info)
  		force_sig_info(signr, info, tsk);
  	else
  		force_sig(signr, tsk);
  	return;

  kernel_trap:
  	if (!fixup_exception(regs)) {
  		tsk->thread.error_code = error_code;
  		tsk->thread.trap_no = trapnr;
  		die(str, regs, error_code);

  	}

  	return;

  #ifdef CONFIG_X86_32

  vm86_trap:
  	if (handle_vm86_trap((struct kernel_vm86_regs *) regs,
  						error_code, trapnr))
  		goto trap_signal;
  	return;

  #endif

  }

  #define DO_ERROR(trapnr, signr, str, name)				\

  dotraplinkage void do_##name(struct pt_regs *regs, long error_code)	\

  {									\
  	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)	\

  							== NOTIFY_STOP)	\

  		return;							\

  	conditional_sti(regs);						\

  	do_trap(trapnr, signr, str, regs, error_code, NULL);		\

  }

  #define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr)		\

  dotraplinkage void do_##name(struct pt_regs *regs, long error_code)	\

  {									\
  	siginfo_t info;							\
  	info.si_signo = signr;						\
  	info.si_errno = 0;						\
  	info.si_code = sicode;						\
  	info.si_addr = (void __user *)siaddr;				\

  	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)	\

  							== NOTIFY_STOP)	\

  		return;							\

  	conditional_sti(regs);						\

  	do_trap(trapnr, signr, str, regs, error_code, &info);		\

  }

  DO_ERROR_INFO(0, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->ip)
  DO_ERROR(4, SIGSEGV, "overflow", overflow)
  DO_ERROR(5, SIGSEGV, "bounds", bounds)
  DO_ERROR_INFO(6, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN, regs->ip)

  DO_ERROR(9, SIGFPE, "coprocessor segment overrun", coprocessor_segment_overrun)

  DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)

  DO_ERROR(11, SIGBUS, "segment not present", segment_not_present)

  #ifdef CONFIG_X86_32

  DO_ERROR(12, SIGBUS, "stack segment", stack_segment)

  #endif

  DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)

  #ifdef CONFIG_X86_64
  /* Runs on IST stack */
  dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
  {
  	if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
  			12, SIGBUS) == NOTIFY_STOP)
  		return;
  	preempt_conditional_sti(regs);
  	do_trap(12, SIGBUS, "stack segment", regs, error_code, NULL);
  	preempt_conditional_cli(regs);
  }
  
  dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
  {
  	static const char str[] = "double fault";
  	struct task_struct *tsk = current;
  
  	/* Return not checked because double check cannot be ignored */
  	notify_die(DIE_TRAP, str, regs, error_code, 8, SIGSEGV);
  
  	tsk->thread.error_code = error_code;
  	tsk->thread.trap_no = 8;

  	/*
  	 * This is always a kernel trap and never fixable (and thus must
  	 * never return).
  	 */

  	for (;;)
  		die(str, regs, error_code);
  }
  #endif

  dotraplinkage void __kprobes

  do_general_protection(struct pt_regs *regs, long error_code)

  {

  	struct task_struct *tsk;

  	conditional_sti(regs);

  #ifdef CONFIG_X86_32

  	if (regs->flags & X86_VM_MASK)

  		goto gp_in_vm86;

  #endif

  	tsk = current;

  	if (!user_mode(regs))

  		goto gp_in_kernel;

  	tsk->thread.error_code = error_code;
  	tsk->thread.trap_no = 13;

  	if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
  			printk_ratelimit()) {

  		printk(KERN_INFO

  			"%s[%d] general protection ip:%lx sp:%lx error:%lx",
  			tsk->comm, task_pid_nr(tsk),
  			regs->ip, regs->sp, error_code);

  		print_vma_addr(" in ", regs->ip);
  		printk("
  ");
  	}

  	force_sig(SIGSEGV, tsk);

  	return;

  #ifdef CONFIG_X86_32

  gp_in_vm86:
  	local_irq_enable();
  	handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
  	return;

  #endif

  
  gp_in_kernel:

  	if (fixup_exception(regs))
  		return;
  
  	tsk->thread.error_code = error_code;
  	tsk->thread.trap_no = 13;
  	if (notify_die(DIE_GPF, "general protection fault", regs,

  				error_code, 13, SIGSEGV) == NOTIFY_STOP)

  		return;
  	die("general protection fault", regs, error_code);

  }

  /* May run on IST stack. */

  dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)

  {

  #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
  	if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
  			== NOTIFY_STOP)
  		return;
  #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */

  	if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
  			== NOTIFY_STOP)

  		return;

  	/*
  	 * Let others (NMI) know that the debug stack is in use
  	 * as we may switch to the interrupt stack.
  	 */
  	debug_stack_usage_inc();

  	preempt_conditional_sti(regs);

  	do_trap(3, SIGTRAP, "int3", regs, error_code, NULL);

  	preempt_conditional_cli(regs);

  	debug_stack_usage_dec();

  }

  #ifdef CONFIG_X86_64

  /*
   * Help handler running on IST stack to switch back to user stack
   * for scheduling or signal handling. The actual stack switch is done in
   * entry.S
   */

  asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
  {
  	struct pt_regs *regs = eregs;
  	/* Did already sync */
  	if (eregs == (struct pt_regs *)eregs->sp)
  		;
  	/* Exception from user space */
  	else if (user_mode(eregs))
  		regs = task_pt_regs(current);

  	/*
  	 * Exception from kernel and interrupts are enabled. Move to
  	 * kernel process stack.
  	 */

  	else if (eregs->flags & X86_EFLAGS_IF)
  		regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
  	if (eregs != regs)
  		*regs = *eregs;
  	return regs;
  }
  #endif

  /*
   * Our handling of the processor debug registers is non-trivial.
   * We do not clear them on entry and exit from the kernel. Therefore
   * it is possible to get a watchpoint trap here from inside the kernel.
   * However, the code in ./ptrace.c has ensured that the user can
   * only set watchpoints on userspace addresses. Therefore the in-kernel
   * watchpoint trap can only occur in code which is reading/writing
   * from user space. Such code must not hold kernel locks (since it
   * can equally take a page fault), therefore it is safe to call
   * force_sig_info even though that claims and releases locks.

   *

   * Code in ./signal.c ensures that the debug control register
   * is restored before we deliver any signal, and therefore that
   * user code runs with the correct debug control register even though
   * we clear it here.
   *
   * Being careful here means that we don't have to be as careful in a
   * lot of more complicated places (task switching can be a bit lazy
   * about restoring all the debug state, and ptrace doesn't have to
   * find every occurrence of the TF bit that could be saved away even
   * by user code)

   *
   * May run on IST stack.

   */

  dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)

  {

  	struct task_struct *tsk = current;

  	int user_icebp = 0;

  	unsigned long dr6;

  	int si_code;

  	get_debugreg(dr6, 6);

  	/* Filter out all the reserved bits which are preset to 1 */
  	dr6 &= ~DR6_RESERVED;

  	/*
  	 * If dr6 has no reason to give us about the origin of this trap,
  	 * then it's very likely the result of an icebp/int01 trap.
  	 * User wants a sigtrap for that.
  	 */
  	if (!dr6 && user_mode(regs))
  		user_icebp = 1;

  	/* Catch kmemcheck conditions first of all! */

  	if ((dr6 & DR_STEP) && kmemcheck_trap(regs))

  		return;

  	/* DR6 may or may not be cleared by the CPU */
  	set_debugreg(0, 6);

  	/*
  	 * The processor cleared BTF, so don't mark that we need it set.
  	 */
  	clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);

  	/* Store the virtualized DR6 value */
  	tsk->thread.debugreg6 = dr6;

  	if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
  							SIGTRAP) == NOTIFY_STOP)

  		return;

  	/*
  	 * Let others (NMI) know that the debug stack is in use
  	 * as we may switch to the interrupt stack.
  	 */
  	debug_stack_usage_inc();

  	/* It's safe to allow irq's after DR6 has been saved */

  	preempt_conditional_sti(regs);

  	if (regs->flags & X86_VM_MASK) {
  		handle_vm86_trap((struct kernel_vm86_regs *) regs,
  				error_code, 1);

  		preempt_conditional_cli(regs);

  		debug_stack_usage_dec();

  		return;

  	}

  	/*

  	 * Single-stepping through system calls: ignore any exceptions in
  	 * kernel space, but re-enable TF when returning to user mode.
  	 *
  	 * We already checked v86 mode above, so we can check for kernel mode
  	 * by just checking the CPL of CS.

  	 */

  	if ((dr6 & DR_STEP) && !user_mode(regs)) {
  		tsk->thread.debugreg6 &= ~DR_STEP;
  		set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
  		regs->flags &= ~X86_EFLAGS_TF;

  	}

  	si_code = get_si_code(tsk->thread.debugreg6);

  	if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)

  		send_sigtrap(tsk, regs, error_code, si_code);

  	preempt_conditional_cli(regs);

  	debug_stack_usage_dec();

  	return;
  }
  
  /*
   * Note that we play around with the 'TS' bit in an attempt to get
   * the correct behaviour even in the presence of the asynchronous
   * IRQ13 behaviour
   */

  void math_error(struct pt_regs *regs, int error_code, int trapnr)

  {

  	struct task_struct *task = current;

  	siginfo_t info;

  	unsigned short err;

  	char *str = (trapnr == 16) ? "fpu exception" : "simd exception";
  
  	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
  		return;
  	conditional_sti(regs);
  
  	if (!user_mode_vm(regs))
  	{
  		if (!fixup_exception(regs)) {
  			task->thread.error_code = error_code;
  			task->thread.trap_no = trapnr;
  			die(str, regs, error_code);
  		}
  		return;
  	}

  
  	/*
  	 * Save the info for the exception handler and clear the error.
  	 */

  	save_init_fpu(task);

  	task->thread.trap_no = trapnr;
  	task->thread.error_code = error_code;

  	info.si_signo = SIGFPE;
  	info.si_errno = 0;

  	info.si_addr = (void __user *)regs->ip;
  	if (trapnr == 16) {
  		unsigned short cwd, swd;
  		/*
  		 * (~cwd & swd) will mask out exceptions that are not set to unmasked
  		 * status.  0x3f is the exception bits in these regs, 0x200 is the
  		 * C1 reg you need in case of a stack fault, 0x040 is the stack
  		 * fault bit.  We should only be taking one exception at a time,
  		 * so if this combination doesn't produce any single exception,
  		 * then we have a bad program that isn't synchronizing its FPU usage
  		 * and it will suffer the consequences since we won't be able to
  		 * fully reproduce the context of the exception
  		 */
  		cwd = get_fpu_cwd(task);
  		swd = get_fpu_swd(task);

  		err = swd & ~cwd;
  	} else {
  		/*
  		 * The SIMD FPU exceptions are handled a little differently, as there
  		 * is only a single status/control register.  Thus, to determine which
  		 * unmasked exception was caught we must mask the exception mask bits
  		 * at 0x1f80, and then use these to mask the exception bits at 0x3f.
  		 */
  		unsigned short mxcsr = get_fpu_mxcsr(task);
  		err = ~(mxcsr >> 7) & mxcsr;
  	}

  
  	if (err & 0x001) {	/* Invalid op */

  		/*
  		 * swd & 0x240 == 0x040: Stack Underflow
  		 * swd & 0x240 == 0x240: Stack Overflow
  		 * User must clear the SF bit (0x40) if set
  		 */
  		info.si_code = FPE_FLTINV;

  	} else if (err & 0x004) { /* Divide by Zero */

  		info.si_code = FPE_FLTDIV;

  	} else if (err & 0x008) { /* Overflow */

  		info.si_code = FPE_FLTOVF;

  	} else if (err & 0x012) { /* Denormal, Underflow */
  		info.si_code = FPE_FLTUND;
  	} else if (err & 0x020) { /* Precision */

  		info.si_code = FPE_FLTRES;

  	} else {

  		/*
  		 * If we're using IRQ 13, or supposedly even some trap 16
  		 * implementations, it's possible we get a spurious trap...
  		 */

  		return;		/* Spurious trap, no error */

  	}
  	force_sig_info(SIGFPE, &info, task);
  }

  dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)

  {

  #ifdef CONFIG_X86_32

  	ignore_fpu_irq = 1;

  #endif

  	math_error(regs, error_code, 16);

  }

  dotraplinkage void
  do_simd_coprocessor_error(struct pt_regs *regs, long error_code)

  {

  	math_error(regs, error_code, 19);

  }

  dotraplinkage void
  do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)

  {

  	conditional_sti(regs);

  #if 0
  	/* No need to warn about this any longer. */

  	printk(KERN_INFO "Ignoring P6 Local APIC Spurious Interrupt Bug...
  ");

  #endif
  }

  asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)

  {

  }

  asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)

  {
  }

  /*

   * __math_state_restore assumes that cr0.TS is already clear and the
   * fpu state is all ready for use.  Used during context switch.
   */
  void __math_state_restore(void)

  {

  	struct thread_info *thread = current_thread_info();
  	struct task_struct *tsk = thread->task;
  
  	/*
  	 * Paranoid restore. send a SIGSEGV if we fail to restore the state.
  	 */
  	if (unlikely(restore_fpu_checking(tsk))) {
  		stts();
  		force_sig(SIGSEGV, tsk);
  		return;
  	}
  
  	thread->status |= TS_USEDFPU;	/* So we fnsave on switch_to() */
  	tsk->fpu_counter++;

  }

  
  /*

   * 'math_state_restore()' saves the current math information in the

   * old math state array, and gets the new ones from the current task
   *
   * Careful.. There are problems with IBM-designed IRQ13 behaviour.
   * Don't touch unless you *really* know how it works.
   *
   * Must be called with kernel preemption disabled (in this case,
   * local interrupts are disabled at the call-site in entry.S).
   */

  asmlinkage void math_state_restore(void)

  {
  	struct thread_info *thread = current_thread_info();
  	struct task_struct *tsk = thread->task;

  	if (!tsk_used_math(tsk)) {
  		local_irq_enable();
  		/*
  		 * does a slab alloc which can sleep
  		 */
  		if (init_fpu(tsk)) {
  			/*
  			 * ran out of memory!
  			 */
  			do_group_exit(SIGKILL);
  			return;
  		}
  		local_irq_disable();
  	}

  	clts();				/* Allow maths ops (or we recurse) */

  	__math_state_restore();

  }

  EXPORT_SYMBOL_GPL(math_state_restore);

  dotraplinkage void __kprobes

  do_device_not_available(struct pt_regs *regs, long error_code)

  {

  #ifdef CONFIG_MATH_EMULATION

  	if (read_cr0() & X86_CR0_EM) {

  		struct math_emu_info info = { };

  		conditional_sti(regs);

  		info.regs = regs;

  		math_emulate(&info);

  		return;

  	}

  #endif
  	math_state_restore(); /* interrupts still off */
  #ifdef CONFIG_X86_32
  	conditional_sti(regs);

  #endif

  }

  #ifdef CONFIG_X86_32

  dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)

  {
  	siginfo_t info;
  	local_irq_enable();
  
  	info.si_signo = SIGILL;
  	info.si_errno = 0;
  	info.si_code = ILL_BADSTK;

  	info.si_addr = NULL;

  	if (notify_die(DIE_TRAP, "iret exception",
  			regs, error_code, 32, SIGILL) == NOTIFY_STOP)
  		return;

  	do_trap(32, SIGILL, "iret exception", regs, error_code, &info);

  }

  #endif

  /* Set of traps needed for early debugging. */
  void __init early_trap_init(void)
  {
  	set_intr_gate_ist(1, &debug, DEBUG_STACK);
  	/* int3 can be called from all */
  	set_system_intr_gate_ist(3, &int3, DEBUG_STACK);
  	set_intr_gate(14, &page_fault);
  	load_idt(&idt_descr);
  }

  void __init trap_init(void)
  {

  	int i;

  #ifdef CONFIG_EISA

  	void __iomem *p = early_ioremap(0x0FFFD9, 4);

  
  	if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))

  		EISA_bus = 1;

  	early_iounmap(p, 4);

  #endif

  	set_intr_gate(0, &divide_error);

  	set_intr_gate_ist(2, &nmi, NMI_STACK);

  	/* int4 can be called from all */
  	set_system_intr_gate(4, &overflow);

  	set_intr_gate(5, &bounds);

  	set_intr_gate(6, &invalid_op);

  	set_intr_gate(7, &device_not_available);

  #ifdef CONFIG_X86_32

  	set_task_gate(8, GDT_ENTRY_DOUBLEFAULT_TSS);

  #else
  	set_intr_gate_ist(8, &double_fault, DOUBLEFAULT_STACK);
  #endif

  	set_intr_gate(9, &coprocessor_segment_overrun);

  	set_intr_gate(10, &invalid_TSS);

  	set_intr_gate(11, &segment_not_present);

  	set_intr_gate_ist(12, &stack_segment, STACKFAULT_STACK);

  	set_intr_gate(13, &general_protection);

  	set_intr_gate(15, &spurious_interrupt_bug);

  	set_intr_gate(16, &coprocessor_error);

  	set_intr_gate(17, &alignment_check);

  #ifdef CONFIG_X86_MCE

  	set_intr_gate_ist(18, &machine_check, MCE_STACK);

  #endif

  	set_intr_gate(19, &simd_coprocessor_error);

  	/* Reserve all the builtin and the syscall vector: */
  	for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
  		set_bit(i, used_vectors);

  #ifdef CONFIG_IA32_EMULATION
  	set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);

  	set_bit(IA32_SYSCALL_VECTOR, used_vectors);

  #endif
  
  #ifdef CONFIG_X86_32

  	set_system_trap_gate(SYSCALL_VECTOR, &system_call);

  	set_bit(SYSCALL_VECTOR, used_vectors);

  #endif

  	/*

  	 * Should be a barrier for any external CPU state:

  	 */
  	cpu_init();

  	x86_init.irqs.trap_init();

  
  #ifdef CONFIG_X86_64
  	memcpy(&nmi_idt_table, &idt_table, IDT_ENTRIES * 16);
  	set_nmi_gate(1, &debug);
  	set_nmi_gate(3, &int3);
  #endif

  }