arch/mn10300/mm/fault.c - kernel/msm-5.4 - Gitiles

 /* MN10300 MMU Fault handler
  *
  * Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  * Modified by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public Licence
  * as published by the Free Software Foundation; either version
  * 2 of the Licence, or (at your option) any later version.
  */

 #include <linux/signal.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/ptrace.h>
 #include <linux/mman.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>
 #include <linux/vt_kern.h>		/* For unblank_screen() */

 #include <asm/system.h>
 #include <asm/uaccess.h>
 #include <asm/pgalloc.h>
 #include <asm/hardirq.h>
 #include <asm/gdb-stub.h>
 #include <asm/cpu-regs.h>

 /*
  * Unlock any spinlocks which will prevent us from getting the
  * message out
  */
 void bust_spinlocks(int yes)
 {
 	if (yes) {
 		oops_in_progress = 1;
 	} else {
 		int loglevel_save = console_loglevel;
 #ifdef CONFIG_VT
 		unblank_screen();
 #endif
 		oops_in_progress = 0;
 		/*
 		 * OK, the message is on the console.  Now we call printk()
 		 * without oops_in_progress set so that printk will give klogd
 		 * a poke.  Hold onto your hats...
 		 */
 		console_loglevel = 15;	/* NMI oopser may have shut the console
 					 * up */
 		printk(" ");
 		console_loglevel = loglevel_save;
 	}
 }

 void do_BUG(const char *file, int line)
 {
 	bust_spinlocks(1);
 	printk(KERN_EMERG "------------[ cut here ]------------\n");
 	printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
 }

 #if 0
 static void print_pagetable_entries(pgd_t *pgdir, unsigned long address)
 {
 	pgd_t *pgd;
 	pmd_t *pmd;
 	pte_t *pte;

 	pgd = pgdir + __pgd_offset(address);
 	printk(KERN_DEBUG "pgd entry %p: %016Lx\n",
 	       pgd, (long long) pgd_val(*pgd));

 	if (!pgd_present(*pgd)) {
 		printk(KERN_DEBUG "... pgd not present!\n");
 		return;
 	}
 	pmd = pmd_offset(pgd, address);
 	printk(KERN_DEBUG "pmd entry %p: %016Lx\n",
 	       pmd, (long long)pmd_val(*pmd));

 	if (!pmd_present(*pmd)) {
 		printk(KERN_DEBUG "... pmd not present!\n");
 		return;
 	}
 	pte = pte_offset(pmd, address);
 	printk(KERN_DEBUG "pte entry %p: %016Lx\n",
 	       pte, (long long) pte_val(*pte));

 	if (!pte_present(*pte))
 		printk(KERN_DEBUG "... pte not present!\n");
 }
 #endif

 /*
  * This routine handles page faults.  It determines the address,
  * and the problem, and then passes it off to one of the appropriate
  * routines.
  *
  * fault_code:
  * - LSW: either MMUFCR_IFC or MMUFCR_DFC as appropriate
  * - MSW: 0 if data access, 1 if instruction access
  * - bit 0: TLB miss flag
  * - bit 1: initial write
  * - bit 2: page invalid
  * - bit 3: protection violation
  * - bit 4: accessor (0=user 1=kernel)
  * - bit 5: 0=read 1=write
  * - bit 6-8: page protection spec
  * - bit 9: illegal address
  * - bit 16: 0=data 1=ins
  *
  */
 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
 			      unsigned long address)
 {
 	struct vm_area_struct *vma;
 	struct task_struct *tsk;
 	struct mm_struct *mm;
 	unsigned long page;
 	siginfo_t info;
 	int write, fault;

 #ifdef CONFIG_GDBSTUB
 	/* handle GDB stub causing a fault */
 	if (gdbstub_busy) {
 		gdbstub_exception(regs, TBR & TBR_INT_CODE);
 		return;
 	}
 #endif

 #if 0
 	printk(KERN_DEBUG "--- do_page_fault(%p,%s:%04lx,%08lx)\n",
 	       regs,
 	       fault_code & 0x10000 ? "ins" : "data",
 	       fault_code & 0xffff, address);
 #endif

 	tsk = current;

 	/*
 	 * We fault-in kernel-space virtual memory on-demand. The
 	 * 'reference' page table is init_mm.pgd.
 	 *
 	 * NOTE! We MUST NOT take any locks for this case. We may
 	 * be in an interrupt or a critical region, and should
 	 * only copy the information from the master page table,
 	 * nothing more.
 	 *
 	 * This verifies that the fault happens in kernel space
 	 * and that the fault was a page not present (invalid) error
 	 */
 	if (address >= VMALLOC_START && address < VMALLOC_END &&
 	    (fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR &&
 	    (fault_code & MMUFCR_xFC_PGINVAL) == MMUFCR_xFC_PGINVAL
 	    )
 		goto vmalloc_fault;

 	mm = tsk->mm;
 	info.si_code = SEGV_MAPERR;

 	/*
 	 * If we're in an interrupt or have no user
 	 * context, we must not take the fault..
 	 */
 	if (in_atomic() || !mm)
 		goto no_context;

 	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 ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
 		/* accessing the stack below the stack pointer is always a
 		 * bug */
 		if ((address & PAGE_MASK) + 2 * PAGE_SIZE < regs->sp) {
 #if 0
 			printk(KERN_WARNING
 			       "[%d] ### Access below stack @%lx (sp=%lx)\n",
 			       current->pid, address, regs->sp);
 			printk(KERN_WARNING
 			       "vma [%08x - %08x]\n",
 			       vma->vm_start, vma->vm_end);
 			show_registers(regs);
 			printk(KERN_WARNING
 			       "[%d] ### Code: [%08lx]"
 			       " %02x %02x %02x %02x %02x %02x %02x %02x\n",
 			       current->pid,
 			       regs->pc,
 			       ((u8 *) regs->pc)[0],
 			       ((u8 *) regs->pc)[1],
 			       ((u8 *) regs->pc)[2],
 			       ((u8 *) regs->pc)[3],
 			       ((u8 *) regs->pc)[4],
 			       ((u8 *) regs->pc)[5],
 			       ((u8 *) regs->pc)[6],
 			       ((u8 *) regs->pc)[7]
 			       );
 #endif
 			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;
 	write = 0;
 	switch (fault_code & (MMUFCR_xFC_PGINVAL|MMUFCR_xFC_TYPE)) {
 	default:	/* 3: write, present */
 	case MMUFCR_xFC_TYPE_WRITE:
 #ifdef TEST_VERIFY_AREA
 		if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
 			printk(KERN_DEBUG "WP fault at %08lx\n", regs->pc);
 #endif
 		/* write to absent page */
 	case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_WRITE:
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
 		write++;
 		break;

 		/* read from protected page */
 	case MMUFCR_xFC_TYPE_READ:
 		goto bad_area;

 		/* read from absent page present */
 	case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_READ:
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
 		break;
 	}

 	/*
 	 * 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(mm, vma, address, 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;

 /*
  * 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);

 	/* User mode accesses just cause a SIGSEGV */
 	if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
 		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, tsk);
 		return;
 	}

 no_context:
 	/* Are we prepared to handle this kernel fault?  */
 	if (fixup_exception(regs))
 		return;

 /*
  * Oops. The kernel tried to access some bad page. We'll have to
  * terminate things with extreme prejudice.
  */

 	bust_spinlocks(1);

 	if (address < PAGE_SIZE)
 		printk(KERN_ALERT
 		       "Unable to handle kernel NULL pointer dereference");
 	else
 		printk(KERN_ALERT
 		       "Unable to handle kernel paging request");
 	printk(" at virtual address %08lx\n", address);
 	printk(" printing pc:\n");
 	printk(KERN_ALERT "%08lx\n", regs->pc);

 #ifdef CONFIG_GDBSTUB
 	gdbstub_intercept(
 		regs, fault_code & 0x00010000 ? EXCEP_IAERROR : EXCEP_DAERROR);
 #endif

 	page = PTBR;
 	page = ((unsigned long *) __va(page))[address >> 22];
 	printk(KERN_ALERT "*pde = %08lx\n", page);
 	if (page & 1) {
 		page &= PAGE_MASK;
 		address &= 0x003ff000;
 		page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
 		printk(KERN_ALERT "*pte = %08lx\n", page);
 	}

 	die("Oops", regs, fault_code);
 	do_exit(SIGKILL);

 /*
  * 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);
 	printk(KERN_ALERT "VM: killing process %s\n", tsk->comm);
 	if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
 		do_exit(SIGKILL);
 	goto no_context;

 do_sigbus:
 	up_read(&mm->mmap_sem);

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

 	/* Kernel mode? Handle exceptions or die */
 	if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
 		goto no_context;
 	return;

 vmalloc_fault:
 	{
 		/*
 		 * Synchronize this task's top level page-table
 		 * with the 'reference' page table.
 		 *
 		 * Do _not_ use "tsk" here. We might be inside
 		 * an interrupt in the middle of a task switch..
 		 */
 		int index = pgd_index(address);
 		pgd_t *pgd, *pgd_k;
 		pud_t *pud, *pud_k;
 		pmd_t *pmd, *pmd_k;
 		pte_t *pte_k;

 		pgd_k = init_mm.pgd + index;

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

 		pud_k = pud_offset(pgd_k, address);
 		if (!pud_present(*pud_k))
 			goto no_context;

 		pmd_k = pmd_offset(pud_k, address);
 		if (!pmd_present(*pmd_k))
 			goto no_context;

 		pgd = (pgd_t *) PTBR + index;
 		pud = pud_offset(pgd, address);
 		pmd = pmd_offset(pud, address);
 		set_pmd(pmd, *pmd_k);

 		pte_k = pte_offset_kernel(pmd_k, address);
 		if (!pte_present(*pte_k))
 			goto no_context;
 		return;
 	}
 }
	/* MN10300 MMU Fault handler
	*
	* Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
	* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
	* Modified by David Howells (dhowells@redhat.com)
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public Licence
	* as published by the Free Software Foundation; either version
	* 2 of the Licence, or (at your option) any later version.
	*/

	#include <linux/signal.h>
	#include <linux/sched.h>
	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/string.h>
	#include <linux/types.h>
	#include <linux/ptrace.h>
	#include <linux/mman.h>
	#include <linux/mm.h>
	#include <linux/smp.h>
	#include <linux/interrupt.h>
	#include <linux/init.h>
	#include <linux/vt_kern.h> /* For unblank_screen() */

	#include <asm/system.h>
	#include <asm/uaccess.h>
	#include <asm/pgalloc.h>
	#include <asm/hardirq.h>
	#include <asm/gdb-stub.h>
	#include <asm/cpu-regs.h>

	/*
	* Unlock any spinlocks which will prevent us from getting the
	* message out
	*/
	void bust_spinlocks(int yes)
	{
	if (yes) {
	oops_in_progress = 1;
	} else {
	int loglevel_save = console_loglevel;
	#ifdef CONFIG_VT
	unblank_screen();
	#endif
	oops_in_progress = 0;
	/*
	* OK, the message is on the console. Now we call printk()
	* without oops_in_progress set so that printk will give klogd
	* a poke. Hold onto your hats...
	*/
	console_loglevel = 15; /* NMI oopser may have shut the console
	* up */
	printk(" ");
	console_loglevel = loglevel_save;
	}
	}

	void do_BUG(const char *file, int line)
	{
	bust_spinlocks(1);
	printk(KERN_EMERG "------------[ cut here ]------------\n");
	printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
	}

	#if 0
	static void print_pagetable_entries(pgd_t *pgdir, unsigned long address)
	{
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;

	pgd = pgdir + __pgd_offset(address);
	printk(KERN_DEBUG "pgd entry %p: %016Lx\n",
	pgd, (long long) pgd_val(*pgd));

	if (!pgd_present(*pgd)) {
	printk(KERN_DEBUG "... pgd not present!\n");
	return;
	}
	pmd = pmd_offset(pgd, address);
	printk(KERN_DEBUG "pmd entry %p: %016Lx\n",
	pmd, (long long)pmd_val(*pmd));

	if (!pmd_present(*pmd)) {
	printk(KERN_DEBUG "... pmd not present!\n");
	return;
	}
	pte = pte_offset(pmd, address);
	printk(KERN_DEBUG "pte entry %p: %016Lx\n",
	pte, (long long) pte_val(*pte));

	if (!pte_present(*pte))
	printk(KERN_DEBUG "... pte not present!\n");
	}
	#endif

	/*
	* This routine handles page faults. It determines the address,
	* and the problem, and then passes it off to one of the appropriate
	* routines.
	*
	* fault_code:
	* - LSW: either MMUFCR_IFC or MMUFCR_DFC as appropriate
	* - MSW: 0 if data access, 1 if instruction access
	* - bit 0: TLB miss flag
	* - bit 1: initial write
	* - bit 2: page invalid
	* - bit 3: protection violation
	* - bit 4: accessor (0=user 1=kernel)
	* - bit 5: 0=read 1=write
	* - bit 6-8: page protection spec
	* - bit 9: illegal address
	* - bit 16: 0=data 1=ins
	*
	*/
	asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
	unsigned long address)
	{
	struct vm_area_struct *vma;
	struct task_struct *tsk;
	struct mm_struct *mm;
	unsigned long page;
	siginfo_t info;
	int write, fault;

	#ifdef CONFIG_GDBSTUB
	/* handle GDB stub causing a fault */
	if (gdbstub_busy) {
	gdbstub_exception(regs, TBR & TBR_INT_CODE);
	return;
	}
	#endif

	#if 0
	printk(KERN_DEBUG "--- do_page_fault(%p,%s:%04lx,%08lx)\n",
	regs,
	fault_code & 0x10000 ? "ins" : "data",
	fault_code & 0xffff, address);
	#endif

	tsk = current;

	/*
	* We fault-in kernel-space virtual memory on-demand. The
	* 'reference' page table is init_mm.pgd.
	*
	* NOTE! We MUST NOT take any locks for this case. We may
	* be in an interrupt or a critical region, and should
	* only copy the information from the master page table,
	* nothing more.
	*
	* This verifies that the fault happens in kernel space
	* and that the fault was a page not present (invalid) error
	*/
	if (address >= VMALLOC_START && address < VMALLOC_END &&
	(fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR &&
	(fault_code & MMUFCR_xFC_PGINVAL) == MMUFCR_xFC_PGINVAL
	)
	goto vmalloc_fault;

	mm = tsk->mm;
	info.si_code = SEGV_MAPERR;

	/*
	* If we're in an interrupt or have no user
	* context, we must not take the fault..
	*/
	if (in_atomic() \|\| !mm)
	goto no_context;

	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 ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
	/* accessing the stack below the stack pointer is always a
	* bug */
	if ((address & PAGE_MASK) + 2 * PAGE_SIZE < regs->sp) {
	#if 0
	printk(KERN_WARNING
	"[%d] ### Access below stack @%lx (sp=%lx)\n",
	current->pid, address, regs->sp);
	printk(KERN_WARNING
	"vma [%08x - %08x]\n",
	vma->vm_start, vma->vm_end);
	show_registers(regs);
	printk(KERN_WARNING
	"[%d] ### Code: [%08lx]"
	" %02x %02x %02x %02x %02x %02x %02x %02x\n",
	current->pid,
	regs->pc,
	((u8 *) regs->pc)[0],
	((u8 *) regs->pc)[1],
	((u8 *) regs->pc)[2],
	((u8 *) regs->pc)[3],
	((u8 *) regs->pc)[4],
	((u8 *) regs->pc)[5],
	((u8 *) regs->pc)[6],
	((u8 *) regs->pc)[7]
	);
	#endif
	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;
	write = 0;
	switch (fault_code & (MMUFCR_xFC_PGINVAL\|MMUFCR_xFC_TYPE)) {
	default: /* 3: write, present */
	case MMUFCR_xFC_TYPE_WRITE:
	#ifdef TEST_VERIFY_AREA
	if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
	printk(KERN_DEBUG "WP fault at %08lx\n", regs->pc);
	#endif
	/* write to absent page */
	case MMUFCR_xFC_PGINVAL \| MMUFCR_xFC_TYPE_WRITE:
	if (!(vma->vm_flags & VM_WRITE))
	goto bad_area;
	write++;
	break;

	/* read from protected page */
	case MMUFCR_xFC_TYPE_READ:
	goto bad_area;

	/* read from absent page present */
	case MMUFCR_xFC_PGINVAL \| MMUFCR_xFC_TYPE_READ:
	if (!(vma->vm_flags & (VM_READ \| VM_EXEC)))
	goto bad_area;
	break;
	}

	/*
	* 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(mm, vma, address, 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;

	/*
	* 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);

	/* User mode accesses just cause a SIGSEGV */
	if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
	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, tsk);
	return;
	}

	no_context:
	/* Are we prepared to handle this kernel fault? */
	if (fixup_exception(regs))
	return;

	/*
	* Oops. The kernel tried to access some bad page. We'll have to
	* terminate things with extreme prejudice.
	*/

	bust_spinlocks(1);

	if (address < PAGE_SIZE)
	printk(KERN_ALERT
	"Unable to handle kernel NULL pointer dereference");
	else
	printk(KERN_ALERT
	"Unable to handle kernel paging request");
	printk(" at virtual address %08lx\n", address);
	printk(" printing pc:\n");
	printk(KERN_ALERT "%08lx\n", regs->pc);

	#ifdef CONFIG_GDBSTUB
	gdbstub_intercept(
	regs, fault_code & 0x00010000 ? EXCEP_IAERROR : EXCEP_DAERROR);
	#endif

	page = PTBR;
	page = ((unsigned long *) __va(page))[address >> 22];
	printk(KERN_ALERT "*pde = %08lx\n", page);
	if (page & 1) {
	page &= PAGE_MASK;
	address &= 0x003ff000;
	page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
	printk(KERN_ALERT "*pte = %08lx\n", page);
	}

	die("Oops", regs, fault_code);
	do_exit(SIGKILL);

	/*
	* 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);
	printk(KERN_ALERT "VM: killing process %s\n", tsk->comm);
	if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
	do_exit(SIGKILL);
	goto no_context;

	do_sigbus:
	up_read(&mm->mmap_sem);

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

	/* Kernel mode? Handle exceptions or die */
	if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
	goto no_context;
	return;

	vmalloc_fault:
	{
	/*
	* Synchronize this task's top level page-table
	* with the 'reference' page table.
	*
	* Do _not_ use "tsk" here. We might be inside
	* an interrupt in the middle of a task switch..
	*/
	int index = pgd_index(address);
	pgd_t pgd, pgd_k;
	pud_t pud, pud_k;
	pmd_t pmd, pmd_k;
	pte_t *pte_k;

	pgd_k = init_mm.pgd + index;

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

	pud_k = pud_offset(pgd_k, address);
	if (!pud_present(*pud_k))
	goto no_context;

	pmd_k = pmd_offset(pud_k, address);
	if (!pmd_present(*pmd_k))
	goto no_context;

	pgd = (pgd_t *) PTBR + index;
	pud = pud_offset(pgd, address);
	pmd = pmd_offset(pud, address);
	set_pmd(pmd, *pmd_k);

	pte_k = pte_offset_kernel(pmd_k, address);
	if (!pte_present(*pte_k))
	goto no_context;
	return;
	}
	}