linux-imx

/*

 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)

 * Licensed under the GPL

 */

​

#include <linux/mm.h>

#include <linux/sched/signal.h>

#include <linux/hardirq.h>

#include <linux/module.h>

#include <linux/uaccess.h>

#include <linux/sched/debug.h>

#include <asm/current.h>

#include <asm/pgtable.h>

#include <asm/tlbflush.h>

#include <arch.h>

#include <as-layout.h>

#include <kern_util.h>

#include <os.h>

#include <skas.h>

​

/*

 * Note this is constrained to return 0, -EFAULT, -EACCES, -ENOMEM by

 * segv().

 */

int handle_page_fault(unsigned long address, unsigned long ip,

              int is_write, int is_user, int *code_out)

{

    struct mm_struct *mm = current->mm;

    struct vm_area_struct *vma;

    pgd_t *pgd;

    pud_t *pud;

    pmd_t *pmd;

    pte_t *pte;

    int err = -EFAULT;

    unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

​

    *code_out = SEGV_MAPERR;

​

    /*

     * If the fault was with pagefaults disabled, don't take the fault, just

     * fail.

     */

    if (faulthandler_disabled())

        goto out_nosemaphore;

​

    if (is_user)

        flags |= FAULT_FLAG_USER;

retry:

    down_read(&mm->mmap_sem);

    vma = find_vma(mm, address);

    if (!vma)

        goto out;

    else if (vma->vm_start <= address)

        goto good_area;

    else if (!(vma->vm_flags & VM_GROWSDOWN))

        goto out;

    else if (is_user && !ARCH_IS_STACKGROW(address))

        goto out;

    else if (expand_stack(vma, address))

        goto out;

​

good_area:

    *code_out = SEGV_ACCERR;

    if (is_write) {

        if (!(vma->vm_flags & VM_WRITE))

            goto out;

        flags |= FAULT_FLAG_WRITE;

    } else {

        /* Don't require VM_READ|VM_EXEC for write faults! */

        if (!(vma->vm_flags & (VM_READ | VM_EXEC)))

            goto out;

    }

​

    do {

        vm_fault_t fault;

​

        fault = handle_mm_fault(vma, address, flags);

​

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

            goto out_nosemaphore;

​

        if (unlikely(fault & VM_FAULT_ERROR)) {

            if (fault & VM_FAULT_OOM) {

                goto out_of_memory;

            } else if (fault & VM_FAULT_SIGSEGV) {

                goto out;

            } else if (fault & VM_FAULT_SIGBUS) {

                err = -EACCES;

                goto out;

            }

            BUG();

        }