diff --git a/mm/mprotect.c b/mm/mprotect.c
new file mode 100644
index 0000000..e9fbd01
--- /dev/null
+++ b/mm/mprotect.c
@@ -0,0 +1,282 @@
+/*
+ *  mm/mprotect.c
+ *
+ *  (C) Copyright 1994 Linus Torvalds
+ *  (C) Copyright 2002 Christoph Hellwig
+ *
+ *  Address space accounting code	<alan@redhat.com>
+ *  (C) Copyright 2002 Red Hat Inc, All Rights Reserved
+ */
+
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/slab.h>
+#include <linux/shm.h>
+#include <linux/mman.h>
+#include <linux/fs.h>
+#include <linux/highmem.h>
+#include <linux/security.h>
+#include <linux/mempolicy.h>
+#include <linux/personality.h>
+#include <linux/syscalls.h>
+
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
+		unsigned long addr, unsigned long end, pgprot_t newprot)
+{
+	pte_t *pte;
+
+	pte = pte_offset_map(pmd, addr);
+	do {
+		if (pte_present(*pte)) {
+			pte_t ptent;
+
+			/* Avoid an SMP race with hardware updated dirty/clean
+			 * bits by wiping the pte and then setting the new pte
+			 * into place.
+			 */
+			ptent = pte_modify(ptep_get_and_clear(mm, addr, pte), newprot);
+			set_pte_at(mm, addr, pte, ptent);
+			lazy_mmu_prot_update(ptent);
+		}
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+	pte_unmap(pte - 1);
+}
+
+static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
+		unsigned long addr, unsigned long end, pgprot_t newprot)
+{
+	pmd_t *pmd;
+	unsigned long next;
+
+	pmd = pmd_offset(pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		if (pmd_none_or_clear_bad(pmd))
+			continue;
+		change_pte_range(mm, pmd, addr, next, newprot);
+	} while (pmd++, addr = next, addr != end);
+}
+
+static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
+		unsigned long addr, unsigned long end, pgprot_t newprot)
+{
+	pud_t *pud;
+	unsigned long next;
+
+	pud = pud_offset(pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_none_or_clear_bad(pud))
+			continue;
+		change_pmd_range(mm, pud, addr, next, newprot);
+	} while (pud++, addr = next, addr != end);
+}
+
+static void change_protection(struct vm_area_struct *vma,
+		unsigned long addr, unsigned long end, pgprot_t newprot)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pgd_t *pgd;
+	unsigned long next;
+	unsigned long start = addr;
+
+	BUG_ON(addr >= end);
+	pgd = pgd_offset(mm, addr);
+	flush_cache_range(vma, addr, end);
+	spin_lock(&mm->page_table_lock);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd))
+			continue;
+		change_pud_range(mm, pgd, addr, next, newprot);
+	} while (pgd++, addr = next, addr != end);
+	flush_tlb_range(vma, start, end);
+	spin_unlock(&mm->page_table_lock);
+}
+
+static int
+mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
+	unsigned long start, unsigned long end, unsigned long newflags)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long oldflags = vma->vm_flags;
+	long nrpages = (end - start) >> PAGE_SHIFT;
+	unsigned long charged = 0;
+	pgprot_t newprot;
+	pgoff_t pgoff;
+	int error;
+
+	if (newflags == oldflags) {
+		*pprev = vma;
+		return 0;
+	}
+
+	/*
+	 * If we make a private mapping writable we increase our commit;
+	 * but (without finer accounting) cannot reduce our commit if we
+	 * make it unwritable again.
+	 *
+	 * FIXME? We haven't defined a VM_NORESERVE flag, so mprotecting
+	 * a MAP_NORESERVE private mapping to writable will now reserve.
+	 */
+	if (newflags & VM_WRITE) {
+		if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED|VM_HUGETLB))) {
+			charged = nrpages;
+			if (security_vm_enough_memory(charged))
+				return -ENOMEM;
+			newflags |= VM_ACCOUNT;
+		}
+	}
+
+	newprot = protection_map[newflags & 0xf];
+
+	/*
+	 * First try to merge with previous and/or next vma.
+	 */
+	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
+	*pprev = vma_merge(mm, *pprev, start, end, newflags,
+			vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
+	if (*pprev) {
+		vma = *pprev;
+		goto success;
+	}
+
+	*pprev = vma;
+
+	if (start != vma->vm_start) {
+		error = split_vma(mm, vma, start, 1);
+		if (error)
+			goto fail;
+	}
+
+	if (end != vma->vm_end) {
+		error = split_vma(mm, vma, end, 0);
+		if (error)
+			goto fail;
+	}
+
+success:
+	/*
+	 * vm_flags and vm_page_prot are protected by the mmap_sem
+	 * held in write mode.
+	 */
+	vma->vm_flags = newflags;
+	vma->vm_page_prot = newprot;
+	change_protection(vma, start, end, newprot);
+	__vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
+	__vm_stat_account(mm, newflags, vma->vm_file, nrpages);
+	return 0;
+
+fail:
+	vm_unacct_memory(charged);
+	return error;
+}
+
+asmlinkage long
+sys_mprotect(unsigned long start, size_t len, unsigned long prot)
+{
+	unsigned long vm_flags, nstart, end, tmp, reqprot;
+	struct vm_area_struct *vma, *prev;
+	int error = -EINVAL;
+	const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
+	prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
+	if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
+		return -EINVAL;
+
+	if (start & ~PAGE_MASK)
+		return -EINVAL;
+	if (!len)
+		return 0;
+	len = PAGE_ALIGN(len);
+	end = start + len;
+	if (end <= start)
+		return -ENOMEM;
+	if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM))
+		return -EINVAL;
+
+	reqprot = prot;
+	/*
+	 * Does the application expect PROT_READ to imply PROT_EXEC:
+	 */
+	if (unlikely((prot & PROT_READ) &&
+			(current->personality & READ_IMPLIES_EXEC)))
+		prot |= PROT_EXEC;
+
+	vm_flags = calc_vm_prot_bits(prot);
+
+	down_write(&current->mm->mmap_sem);
+
+	vma = find_vma_prev(current->mm, start, &prev);
+	error = -ENOMEM;
+	if (!vma)
+		goto out;
+	if (unlikely(grows & PROT_GROWSDOWN)) {
+		if (vma->vm_start >= end)
+			goto out;
+		start = vma->vm_start;
+		error = -EINVAL;
+		if (!(vma->vm_flags & VM_GROWSDOWN))
+			goto out;
+	}
+	else {
+		if (vma->vm_start > start)
+			goto out;
+		if (unlikely(grows & PROT_GROWSUP)) {
+			end = vma->vm_end;
+			error = -EINVAL;
+			if (!(vma->vm_flags & VM_GROWSUP))
+				goto out;
+		}
+	}
+	if (start > vma->vm_start)
+		prev = vma;
+
+	for (nstart = start ; ; ) {
+		unsigned long newflags;
+
+		/* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
+
+		if (is_vm_hugetlb_page(vma)) {
+			error = -EACCES;
+			goto out;
+		}
+
+		newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
+
+		if ((newflags & ~(newflags >> 4)) & 0xf) {
+			error = -EACCES;
+			goto out;
+		}
+
+		error = security_file_mprotect(vma, reqprot, prot);
+		if (error)
+			goto out;
+
+		tmp = vma->vm_end;
+		if (tmp > end)
+			tmp = end;
+		error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
+		if (error)
+			goto out;
+		nstart = tmp;
+
+		if (nstart < prev->vm_end)
+			nstart = prev->vm_end;
+		if (nstart >= end)
+			goto out;
+
+		vma = prev->vm_next;
+		if (!vma || vma->vm_start != nstart) {
+			error = -ENOMEM;
+			goto out;
+		}
+	}
+out:
+	up_write(&current->mm->mmap_sem);
+	return error;
+}