mem_32.c

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/*
 * Copyright (C) 2011 Richard Weinberger <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/mm.h>
#include <asm/page.h>
#include <asm/mman.h>

static struct vm_area_struct gate_vma;

static int __init gate_vma_init(void)
{
    if (!FIXADDR_USER_START)
        return 0;

    gate_vma.vm_mm = NULL;
    gate_vma.vm_start = FIXADDR_USER_START;
    gate_vma.vm_end = FIXADDR_USER_END;
    gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
    gate_vma.vm_page_prot = __P101;

    return 0;
}
__initcall(gate_vma_init);

struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
    return FIXADDR_USER_START ? &gate_vma : NULL;
}

int in_gate_area_no_mm(unsigned long addr)
{
    if (!FIXADDR_USER_START)
        return 0;

    if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
        return 1;

    return 0;
}

int in_gate_area(struct mm_struct *mm, unsigned long addr)
{
    struct vm_area_struct *vma = get_gate_vma(mm);

    if (!vma)
        return 0;

    return (addr >= vma->vm_start) && (addr < vma->vm_end);
}