spu_fault.c

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/*
 * SPU mm fault handler
 *
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2007
 *
 * Author: Arnd Bergmann <[email protected]>
 * Author: Jeremy Kerr <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/export.h>

#include <asm/spu.h>
#include <asm/spu_csa.h>

/*
 * This ought to be kept in sync with the powerpc specific do_page_fault
 * function. Currently, there are a few corner cases that we haven't had
 * to handle fortunately.
 */
int spu_handle_mm_fault(struct mm_struct *mm, unsigned long ea,
        unsigned long dsisr, unsigned *flt)
{
    struct vm_area_struct *vma;
    unsigned long is_write;
    int ret;

    if (mm == NULL)
        return -EFAULT;

    if (mm->pgd == NULL)
        return -EFAULT;

    down_read(&mm->mmap_sem);
    ret = -EFAULT;
    vma = find_vma(mm, ea);
    if (!vma)
        goto out_unlock;

    if (ea < vma->vm_start) {
        if (!(vma->vm_flags & VM_GROWSDOWN))
            goto out_unlock;
        if (expand_stack(vma, ea))
            goto out_unlock;
    }

    is_write = dsisr & MFC_DSISR_ACCESS_PUT;
    if (is_write) {
        if (!(vma->vm_flags & VM_WRITE))
            goto out_unlock;
    } else {
        if (dsisr & MFC_DSISR_ACCESS_DENIED)
            goto out_unlock;
        if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
            goto out_unlock;
    }

    ret = 0;
    *flt = handle_mm_fault(mm, vma, ea, is_write ? FAULT_FLAG_WRITE : 0);
    if (unlikely(*flt & VM_FAULT_ERROR)) {
        if (*flt & VM_FAULT_OOM) {
            ret = -ENOMEM;
            goto out_unlock;
        } else if (*flt & VM_FAULT_SIGBUS) {
            ret = -EFAULT;
            goto out_unlock;
        }
        BUG();
    }

    if (*flt & VM_FAULT_MAJOR)
        current->maj_flt++;
    else
        current->min_flt++;

out_unlock:
    up_read(&mm->mmap_sem);
    return ret;
}
EXPORT_SYMBOL_GPL(spu_handle_mm_fault);