Example #1
0
void
MachineCheckException(struct pt_regs *regs)
{
#ifdef CONFIG_ALL_PPC
	unsigned long fixup;
#endif /* CONFIG_ALL_PPC */

	if (user_mode(regs)) {
		_exception(SIGSEGV, regs);	
		return;
	}

#if defined(CONFIG_8xx) && defined(CONFIG_PCI)
	/* the qspan pci read routines can cause machine checks -- Cort */
	bad_page_fault(regs, regs->dar);
	return;
#endif
#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
	if (debugger_fault_handler) {
		debugger_fault_handler(regs);
		return;
	}
#endif

#ifdef CONFIG_ALL_PPC
	/*
	 * I/O accesses can cause machine checks on powermacs.
	 * Check if the NIP corresponds to the address of a sync
	 * instruction for which there is an entry in the exception
	 * table.
	 */
	if (regs->msr & (0x80000 | 0x40000)
	    && (fixup = search_exception_table(regs->nip)) != 0) {
		/*
		 * Check that it's a sync instruction.
		 * As the address is in the exception table
		 * we should be able to read the instr there.
		 */
		if (*(unsigned int *)regs->nip == 0x7c0004ac) {
			unsigned int lsi = ((unsigned int *)regs->nip)[-1];
			int rb = (lsi >> 11) & 0x1f;
			printk(KERN_DEBUG "%s bad port %lx at %lx\n",
			       (lsi & 0x100)? "OUT to": "IN from",
			       regs->gpr[rb] - _IO_BASE, regs->nip);
			regs->nip = fixup;
			return;
		}
	}
Example #2
0
void
MachineCheckException(struct pt_regs *regs)
{
	if ( !user_mode(regs) )
	{
#ifdef CONFIG_MBX
		/* the mbx pci read routines can cause machine checks -- Cort */
		bad_page_fault(regs,regs->dar);
		return;
#endif /* CONFIG_MBX */
#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
		if (debugger_fault_handler) {
			debugger_fault_handler(regs);
			return;
		}
#endif
		printk("Machine check in kernel mode.\n");
		printk("Caused by (from msr): ");
		printk("regs %p ",regs);
		switch( regs->msr & 0x0000F000)
		{
		case (1<<12) :
			printk("Machine check signal - probably due to mm fault\n"
				"with mmu off\n");
			break;
		case (1<<13) :
			printk("Transfer error ack signal\n");
			break;
		case (1<<14) :
			printk("Data parity signal\n");
			break;
		case (1<<15) :
			printk("Address parity signal\n");
			break;
		default:
			printk("Unknown values in msr\n");
		}
		show_regs(regs);
#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
		debugger(regs);
#endif
		print_backtrace((unsigned long *)regs->gpr[1]);
		instruction_dump((unsigned long *)regs->nip);
		panic("machine check");
	}
	_exception(SIGSEGV, regs);	
}
Example #3
0
void
AlignmentException(struct pt_regs *regs)
{
	int fixed;

#ifdef __SMP__
	if (regs->msr & MSR_FP )
		smp_giveup_fpu(current);
#else	
	if (last_task_used_math == current)
		giveup_fpu();
#endif	
	fixed = fix_alignment(regs);
	if (fixed == 1) {
		regs->nip += 4;	/* skip over emulated instruction */
		return;
	}
	if (fixed == -EFAULT) {
		/* fixed == -EFAULT means the operand address was bad */
		bad_page_fault(regs, regs->dar);
		return;
	}
	_exception(SIGBUS, regs);	
}
Example #4
0
void
AlignmentException(struct pt_regs *regs)
{
	int fixed;
	siginfo_t info;

	fixed = fix_alignment(regs);

	if (fixed == 1) {
		regs->nip += 4;	/* skip over emulated instruction */
		emulate_single_step(regs);
		return;
	}

	/* Operand address was bad */	
	if (fixed == -EFAULT) {
		if (user_mode(regs)) {
			info.si_signo = SIGSEGV;
			info.si_errno = 0;
			info.si_code = SEGV_MAPERR;
			info.si_addr = (void *)regs->dar;
			force_sig_info(SIGSEGV, &info, current);
		} else {
			/* Search exception table */
			bad_page_fault(regs, regs->dar, SIGSEGV);
		}

		return;
	}

	info.si_signo = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRALN;
	info.si_addr = (void *)regs->nip;
	_exception(SIGBUS, &info, regs);	
}
Example #5
0
void do_page_fault(struct pt_regs *regs)
{
	struct vm_area_struct * vma;
	struct mm_struct *mm = current->mm;
	unsigned int exccause = regs->exccause;
	unsigned int address = regs->excvaddr;
	siginfo_t info;

	int is_write, is_exec;
	int fault;
	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

	info.si_code = SEGV_MAPERR;

	/* We fault-in kernel-space virtual memory on-demand. The
	 * 'reference' page table is init_mm.pgd.
	 */
	if (address >= TASK_SIZE && !user_mode(regs))
		goto vmalloc_fault;

	/* If we're in an interrupt or have no user
	 * context, we must not take the fault..
	 */
	if (faulthandler_disabled() || !mm) {
		bad_page_fault(regs, address, SIGSEGV);
		return;
	}

	is_write = (exccause == EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0;
	is_exec =  (exccause == EXCCAUSE_ITLB_PRIVILEGE ||
		    exccause == EXCCAUSE_ITLB_MISS ||
		    exccause == EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0;

#ifdef DEBUG_PAGE_FAULT
	printk("[%s:%d:%08x:%d:%08x:%s%s]\n", current->comm, current->pid,
	       address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");
#endif

	if (user_mode(regs))
		flags |= FAULT_FLAG_USER;
retry:
	down_read(&mm->mmap_sem);
	vma = find_vma(mm, address);

	if (!vma)
		goto bad_area;
	if (vma->vm_start <= address)
		goto good_area;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		goto bad_area;
	if (expand_stack(vma, address))
		goto bad_area;

	/* Ok, we have a good vm_area for this memory access, so
	 * we can handle it..
	 */

good_area:
	info.si_code = SEGV_ACCERR;

	if (is_write) {
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
		flags |= FAULT_FLAG_WRITE;
	} else if (is_exec) {
		if (!(vma->vm_flags & VM_EXEC))
			goto bad_area;
	} else	/* Allow read even from write-only pages. */
		if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
			goto bad_area;

	/* If for any reason at all we couldn't handle the fault,
	 * make sure we exit gracefully rather than endlessly redo
	 * the fault.
	 */
	fault = handle_mm_fault(vma, address, flags);

	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
		return;

	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGSEGV)
			goto bad_area;
		else if (fault & VM_FAULT_SIGBUS)
			goto do_sigbus;
		BUG();
	}
	if (flags & FAULT_FLAG_ALLOW_RETRY) {
		if (fault & VM_FAULT_MAJOR)
			current->maj_flt++;
		else
			current->min_flt++;
		if (fault & VM_FAULT_RETRY) {
			flags &= ~FAULT_FLAG_ALLOW_RETRY;
			flags |= FAULT_FLAG_TRIED;

			 /* No need to up_read(&mm->mmap_sem) as we would
			 * have already released it in __lock_page_or_retry
			 * in mm/filemap.c.
			 */

			goto retry;
		}
	}

	up_read(&mm->mmap_sem);
	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
	if (flags & VM_FAULT_MAJOR)
		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
	else
		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);

	return;

	/* Something tried to access memory that isn't in our memory map..
	 * Fix it, but check if it's kernel or user first..
	 */
bad_area:
	up_read(&mm->mmap_sem);
	if (user_mode(regs)) {
		current->thread.bad_vaddr = address;
		current->thread.error_code = is_write;
		info.si_signo = SIGSEGV;
		info.si_errno = 0;
		/* info.si_code has been set above */
		info.si_addr = (void *) address;
		force_sig_info(SIGSEGV, &info, current);
		return;
	}
	bad_page_fault(regs, address, SIGSEGV);
	return;


	/* We ran out of memory, or some other thing happened to us that made
	 * us unable to handle the page fault gracefully.
	 */
out_of_memory:
	up_read(&mm->mmap_sem);
	if (!user_mode(regs))
		bad_page_fault(regs, address, SIGKILL);
	else
		pagefault_out_of_memory();
	return;

do_sigbus:
	up_read(&mm->mmap_sem);

	/* Send a sigbus, regardless of whether we were in kernel
	 * or user mode.
	 */
	current->thread.bad_vaddr = address;
	info.si_code = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRERR;
	info.si_addr = (void *) address;
	force_sig_info(SIGBUS, &info, current);

	/* Kernel mode? Handle exceptions or die */
	if (!user_mode(regs))
		bad_page_fault(regs, address, SIGBUS);
	return;

vmalloc_fault:
	{
		/* Synchronize this task's top level page-table
		 * with the 'reference' page table.
		 */
		struct mm_struct *act_mm = current->active_mm;
		int index = pgd_index(address);
		pgd_t *pgd, *pgd_k;
		pmd_t *pmd, *pmd_k;
		pte_t *pte_k;

		if (act_mm == NULL)
			goto bad_page_fault;

		pgd = act_mm->pgd + index;
		pgd_k = init_mm.pgd + index;

		if (!pgd_present(*pgd_k))
			goto bad_page_fault;

		pgd_val(*pgd) = pgd_val(*pgd_k);

		pmd = pmd_offset(pgd, address);
		pmd_k = pmd_offset(pgd_k, address);
		if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
			goto bad_page_fault;

		pmd_val(*pmd) = pmd_val(*pmd_k);
		pte_k = pte_offset_kernel(pmd_k, address);

		if (!pte_present(*pte_k))
			goto bad_page_fault;
		return;
	}
bad_page_fault:
	bad_page_fault(regs, address, SIGKILL);
	return;
}
void do_page_fault(struct pt_regs *regs)
{
	struct vm_area_struct * vma;
	struct mm_struct *mm = current->mm;
	unsigned int exccause = regs->exccause;
	unsigned int address = regs->excvaddr;
	siginfo_t info;

	int is_write, is_exec;
	int fault;

	info.si_code = SEGV_MAPERR;

	if (address >= TASK_SIZE && !user_mode(regs))
		goto vmalloc_fault;

	if (in_atomic() || !mm) {
		bad_page_fault(regs, address, SIGSEGV);
		return;
	}

	is_write = (exccause == EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0;
	is_exec =  (exccause == EXCCAUSE_ITLB_PRIVILEGE ||
		    exccause == EXCCAUSE_ITLB_MISS ||
		    exccause == EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0;

#ifdef DEBUG_PAGE_FAULT
	printk("[%s:%d:%08x:%d:%08x:%s%s]\n", current->comm, current->pid,
	       address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");
#endif

	down_read(&mm->mmap_sem);
	vma = find_vma(mm, address);

	if (!vma)
		goto bad_area;
	if (vma->vm_start <= address)
		goto good_area;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		goto bad_area;
	if (expand_stack(vma, address))
		goto bad_area;


good_area:
	info.si_code = SEGV_ACCERR;

	if (is_write) {
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
	} else if (is_exec) {
		if (!(vma->vm_flags & VM_EXEC))
			goto bad_area;
	} else	
		if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
			goto bad_area;

	fault = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0);
	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGBUS)
			goto do_sigbus;
		BUG();
	}
	if (fault & VM_FAULT_MAJOR)
		current->maj_flt++;
	else
		current->min_flt++;

	up_read(&mm->mmap_sem);
	return;

bad_area:
	up_read(&mm->mmap_sem);
	if (user_mode(regs)) {
		current->thread.bad_vaddr = address;
		current->thread.error_code = is_write;
		info.si_signo = SIGSEGV;
		info.si_errno = 0;
		
		info.si_addr = (void *) address;
		force_sig_info(SIGSEGV, &info, current);
		return;
	}
	bad_page_fault(regs, address, SIGSEGV);
	return;


out_of_memory:
	up_read(&mm->mmap_sem);
	if (!user_mode(regs))
		bad_page_fault(regs, address, SIGKILL);
	else
		pagefault_out_of_memory();
	return;

do_sigbus:
	up_read(&mm->mmap_sem);

	current->thread.bad_vaddr = address;
	info.si_code = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRERR;
	info.si_addr = (void *) address;
	force_sig_info(SIGBUS, &info, current);

	
	if (!user_mode(regs))
		bad_page_fault(regs, address, SIGBUS);

vmalloc_fault:
	{
		struct mm_struct *act_mm = current->active_mm;
		int index = pgd_index(address);
		pgd_t *pgd, *pgd_k;
		pmd_t *pmd, *pmd_k;
		pte_t *pte_k;

		if (act_mm == NULL)
			goto bad_page_fault;

		pgd = act_mm->pgd + index;
		pgd_k = init_mm.pgd + index;

		if (!pgd_present(*pgd_k))
			goto bad_page_fault;

		pgd_val(*pgd) = pgd_val(*pgd_k);

		pmd = pmd_offset(pgd, address);
		pmd_k = pmd_offset(pgd_k, address);
		if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
			goto bad_page_fault;

		pmd_val(*pmd) = pmd_val(*pmd_k);
		pte_k = pte_offset_kernel(pmd_k, address);

		if (!pte_present(*pte_k))
			goto bad_page_fault;
		return;
	}
bad_page_fault:
	bad_page_fault(regs, address, SIGKILL);
	return;
}
Example #7
0
/*
 * For 600- and 800-family processors, the error_code parameter is DSISR
 * for a data fault, SRR1 for an instruction fault. For 400-family processors
 * the error_code parameter is ESR for a data fault, 0 for an instruction
 * fault.
 */
void do_page_fault(struct pt_regs *regs, unsigned long address,
		   unsigned long error_code)
{
	struct vm_area_struct * vma;
	struct mm_struct *mm = current->mm;
	siginfo_t info;
	int code = SEGV_MAPERR;
#if defined(CONFIG_4xx)
	int is_write = error_code & ESR_DST;
#else
	int is_write = 0;

	/*
	 * Fortunately the bit assignments in SRR1 for an instruction
	 * fault and DSISR for a data fault are mostly the same for the
	 * bits we are interested in.  But there are some bits which
	 * indicate errors in DSISR but can validly be set in SRR1.
	 */
	if (regs->trap == 0x400)
		error_code &= 0x48200000;
	else
		is_write = error_code & 0x02000000;
#endif /* CONFIG_4xx */

#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
	if (debugger_fault_handler && regs->trap == 0x300) {
		debugger_fault_handler(regs);
		return;
	}
#if !defined(CONFIG_4xx)
	if (error_code & 0x00400000) {
		/* DABR match */
		if (debugger_dabr_match(regs))
			return;
	}
#endif /* !CONFIG_4xx */
#endif /* CONFIG_XMON || CONFIG_KGDB */

	if (in_interrupt() || mm == NULL) {
		bad_page_fault(regs, address);
		return;
	}
	down(&mm->mmap_sem);
	vma = find_vma(mm, address);
	if (!vma)
		goto bad_area;
	if (vma->vm_start <= address)
		goto good_area;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		goto bad_area;
	if (expand_stack(vma, address))
		goto bad_area;

good_area:
	code = SEGV_ACCERR;
#if defined(CONFIG_6xx)
	if (error_code & 0x95700000)
		/* an error such as lwarx to I/O controller space,
		   address matching DABR, eciwx, etc. */
		goto bad_area;
#endif /* CONFIG_6xx */
#if defined(CONFIG_8xx)
        /* The MPC8xx seems to always set 0x80000000, which is
         * "undefined".  Of those that can be set, this is the only
         * one which seems bad.
         */
	if (error_code & 0x10000000)
                /* Guarded storage error. */
		goto bad_area;
#endif /* CONFIG_8xx */
	
	/* a write */
	if (is_write) {
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
	/* a read */
	} else {
		/* protection fault */
		if (error_code & 0x08000000)
			goto bad_area;
		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
			goto bad_area;
	}

	/*
	 * If for any reason at all we couldn't handle the fault,
	 * make sure we exit gracefully rather than endlessly redo
	 * the fault.
	 */
        switch (handle_mm_fault(mm, vma, address, is_write)) {
        case 1:
                current->min_flt++;
                break;
        case 2:
                current->maj_flt++;
                break;
        case 0:
                goto do_sigbus;
        default:
                goto out_of_memory;
	}

	up(&mm->mmap_sem);
	/*
	 * keep track of tlb+htab misses that are good addrs but
	 * just need pte's created via handle_mm_fault()
	 * -- Cort
	 */
	pte_misses++;
	return;

bad_area:
	up(&mm->mmap_sem);
	pte_errors++;	

	/* User mode accesses cause a SIGSEGV */
	if (user_mode(regs)) {
		info.si_signo = SIGSEGV;
		info.si_errno = 0;
		info.si_code = code;
		info.si_addr = (void *) address;
		force_sig_info(SIGSEGV, &info, current);
		return;
	}

	bad_page_fault(regs, address);
	return;

/*
 * We ran out of memory, or some other thing happened to us that made
 * us unable to handle the page fault gracefully.
 */
out_of_memory:
	up(&mm->mmap_sem);
	printk("VM: killing process %s\n", current->comm);
	if (user_mode(regs))
		do_exit(SIGKILL);
	bad_page_fault(regs, address);
	return;

do_sigbus:
	up(&mm->mmap_sem);
	info.si_signo = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRERR;
	info.si_addr = (void *)address;
	force_sig_info (SIGBUS, &info, current);
	if (!user_mode(regs))
		bad_page_fault(regs, address);
}
Example #8
0
void do_page_fault(struct pt_regs *regs)
{
	struct vm_area_struct * vma;
	struct mm_struct *mm = current->mm;
	unsigned int exccause = regs->exccause;
	unsigned int address = regs->excvaddr;
	siginfo_t info;
	int is_write, is_exec;

	is_write = (exccause == EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0;
	is_exec =  (exccause == EXCCAUSE_ITLB_PRIVILEGE ||
		    exccause == EXCCAUSE_ITLB_MISS ||
		    exccause == EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0;

#if DEBUG_PAGE_FAULT
	printk("[%s:%d:%08x:%d:%08lx:%s%s]\n", current->comm, current->pid,
	       address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");
#endif

	info.si_code = SEGV_MAPERR;

	/* We fault-in kernel-space virtual memory on-demand. The
	 * 'reference' page table is init_mm.pgd.
	 */
	if (address >= TASK_SIZE && !user_mode(regs))
		goto vmalloc_fault;

	/* If we're in an interrupt or have no user
	 * context, we must not take the fault..
	 */
	if (in_atomic() || !mm) {
		bad_page_fault(regs, address, SIGSEGV);
		return;
	}

	down_read(&mm->mmap_sem);
	vma = find_vma(mm, address);

	if (!vma)
		goto bad_area;
	if (vma->vm_start <= address)
		goto good_area;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		goto bad_area;
	if (expand_stack(vma, address))
		goto bad_area;

	/* Ok, we have a good vm_area for this memory access, so
	 * we can handle it..
	 */

good_area:
	info.si_code = SEGV_ACCERR;

	if (is_write) {
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
	} else if (is_exec) {
		if (!(vma->vm_flags & VM_EXEC))
			goto bad_area;
	} else	/* Allow read even from write-only pages. */
		if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
			goto bad_area;

	/* If for any reason at all we couldn't handle the fault,
	 * make sure we exit gracefully rather than endlessly redo
	 * the fault.
	 */
survive:
	switch (handle_mm_fault(mm, vma, address, is_write)) {
	case VM_FAULT_MINOR:
		current->min_flt++;
		break;
	case VM_FAULT_MAJOR:
		current->maj_flt++;
		break;
	case VM_FAULT_SIGBUS:
		goto do_sigbus;
	case VM_FAULT_OOM:
		goto out_of_memory;
	default:
		BUG();
	}

	up_read(&mm->mmap_sem);
	return;

	/* Something tried to access memory that isn't in our memory map..
	 * Fix it, but check if it's kernel or user first..
	 */
bad_area:
	up_read(&mm->mmap_sem);
	if (user_mode(regs)) {
		current->thread.bad_vaddr = address;
		current->thread.error_code = is_write;
		info.si_signo = SIGSEGV;
		info.si_errno = 0;
		/* info.si_code has been set above */
		info.si_addr = (void *) address;
		force_sig_info(SIGSEGV, &info, current);
		return;
	}
	bad_page_fault(regs, address, SIGSEGV);
	return;


	/* We ran out of memory, or some other thing happened to us that made
	 * us unable to handle the page fault gracefully.
	 */
out_of_memory:
	up_read(&mm->mmap_sem);
	if (current->pid == 1) {
		yield();
		down_read(&mm->mmap_sem);
		goto survive;
	}
	printk("VM: killing process %s\n", current->comm);
	if (user_mode(regs))
		do_exit(SIGKILL);
	bad_page_fault(regs, address, SIGKILL);
	return;

do_sigbus:
	up_read(&mm->mmap_sem);

	/* Send a sigbus, regardless of whether we were in kernel
	 * or user mode.
	 */
	current->thread.bad_vaddr = address;
	info.si_code = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRERR;
	info.si_addr = (void *) address;
	force_sig_info(SIGBUS, &info, current);

	/* Kernel mode? Handle exceptions or die */
	if (!user_mode(regs))
		bad_page_fault(regs, address, SIGBUS);

vmalloc_fault:
	{
		/* Synchronize this task's top level page-table
		 * with the 'reference' page table.
		 */
		struct mm_struct *act_mm = current->active_mm;
		int index = pgd_index(address);
		pgd_t *pgd, *pgd_k;
		pmd_t *pmd, *pmd_k;
		pte_t *pte_k;

		if (act_mm == NULL)
			goto bad_page_fault;

		pgd = act_mm->pgd + index;
		pgd_k = init_mm.pgd + index;

		if (!pgd_present(*pgd_k))
			goto bad_page_fault;

		pgd_val(*pgd) = pgd_val(*pgd_k);

		pmd = pmd_offset(pgd, address);
		pmd_k = pmd_offset(pgd_k, address);
		if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
			goto bad_page_fault;

		pmd_val(*pmd) = pmd_val(*pmd_k);
		pte_k = pte_offset_kernel(pmd_k, address);

		if (!pte_present(*pte_k))
			goto bad_page_fault;
		return;
	}
bad_page_fault:
	bad_page_fault(regs, address, SIGKILL);
	return;
}