[mirror_ubuntu-bionic-kernel.git] / mm / mprotect.c

/*
 *  mm/mprotect.c
 *
 *  (C) Copyright 1994 Linus Torvalds
 *  (C) Copyright 2002 Christoph Hellwig
 *
 *  Address space accounting code	<alan@lxorguk.ukuu.org.uk>
 *  (C) Copyright 2002 Red Hat Inc, All Rights Reserved
 */

#include <linux/mm.h>
#include <linux/hugetlb.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 <linux/swap.h>
#include <linux/swapops.h>
#include <linux/mmu_notifier.h>
#include <linux/migrate.h>
#include <linux/perf_event.h>
#include <linux/ksm.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>

#ifndef pgprot_modify
static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
{
	return newprot;
}
#endif

/*
 * For a prot_numa update we only hold mmap_sem for read so there is a
 * potential race with faulting where a pmd was temporarily none. This
 * function checks for a transhuge pmd under the appropriate lock. It
 * returns a pte if it was successfully locked or NULL if it raced with
 * a transhuge insertion.
 */
static pte_t *lock_pte_protection(struct vm_area_struct *vma, pmd_t *pmd,
			unsigned long addr, int prot_numa, spinlock_t **ptl)
{
	pte_t *pte;
	spinlock_t *pmdl;

	/* !prot_numa is protected by mmap_sem held for write */
	if (!prot_numa)
		return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);

	pmdl = pmd_lock(vma->vm_mm, pmd);
	if (unlikely(pmd_trans_huge(*pmd) || pmd_none(*pmd))) {
		spin_unlock(pmdl);
		return NULL;
	}

	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
	spin_unlock(pmdl);
	return pte;
}

static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
		unsigned long addr, unsigned long end, pgprot_t newprot,
		int dirty_accountable, int prot_numa)
{
	struct mm_struct *mm = vma->vm_mm;
	pte_t *pte, oldpte;
	spinlock_t *ptl;
	unsigned long pages = 0;

	pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
	if (!pte)
		return 0;

	arch_enter_lazy_mmu_mode();
	do {
		oldpte = *pte;
		if (pte_present(oldpte)) {
			pte_t ptent;
			bool updated = false;

			if (!prot_numa) {
				ptent = ptep_modify_prot_start(mm, addr, pte);
				if (pte_numa(ptent))
					ptent = pte_mknonnuma(ptent);
				ptent = pte_modify(ptent, newprot);
				/*
				 * Avoid taking write faults for pages we
				 * know to be dirty.
				 */
				if (dirty_accountable && pte_dirty(ptent))
					ptent = pte_mkwrite(ptent);
				ptep_modify_prot_commit(mm, addr, pte, ptent);
				updated = true;
			} else {
				struct page *page;

				page = vm_normal_page(vma, addr, oldpte);
				if (page && !PageKsm(page)) {
					if (!pte_numa(oldpte)) {
						ptep_set_numa(mm, addr, pte);
						updated = true;
					}
				}
			}
			if (updated)
				pages++;
		} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
			swp_entry_t entry = pte_to_swp_entry(oldpte);

			if (is_write_migration_entry(entry)) {
				pte_t newpte;
				/*
				 * A protection check is difficult so
				 * just be safe and disable write
				 */
				make_migration_entry_read(&entry);
				newpte = swp_entry_to_pte(entry);
				if (pte_swp_soft_dirty(oldpte))
					newpte = pte_swp_mksoft_dirty(newpte);
				set_pte_at(mm, addr, pte, newpte);

				pages++;
			}
		}
	} while (pte++, addr += PAGE_SIZE, addr != end);
	arch_leave_lazy_mmu_mode();
	pte_unmap_unlock(pte - 1, ptl);

	return pages;
}

static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
		pud_t *pud, unsigned long addr, unsigned long end,
		pgprot_t newprot, int dirty_accountable, int prot_numa)
{
	pmd_t *pmd;
	struct mm_struct *mm = vma->vm_mm;
	unsigned long next;
	unsigned long pages = 0;
	unsigned long nr_huge_updates = 0;
	unsigned long mni_start = 0;

	pmd = pmd_offset(pud, addr);
	do {
		unsigned long this_pages;

		next = pmd_addr_end(addr, end);
		if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd))
			continue;

		/* invoke the mmu notifier if the pmd is populated */
		if (!mni_start) {
			mni_start = addr;
			mmu_notifier_invalidate_range_start(mm, mni_start, end);
		}

		if (pmd_trans_huge(*pmd)) {
			if (next - addr != HPAGE_PMD_SIZE)
				split_huge_page_pmd(vma, addr, pmd);
			else {
				int nr_ptes = change_huge_pmd(vma, pmd, addr,
						newprot, prot_numa);

				if (nr_ptes) {
					if (nr_ptes == HPAGE_PMD_NR) {
						pages += HPAGE_PMD_NR;
						nr_huge_updates++;
					}

					/* huge pmd was handled */
					continue;
				}
			}
			/* fall through, the trans huge pmd just split */
		}
		this_pages = change_pte_range(vma, pmd, addr, next, newprot,
				 dirty_accountable, prot_numa);
		pages += this_pages;
	} while (pmd++, addr = next, addr != end);

	if (mni_start)
		mmu_notifier_invalidate_range_end(mm, mni_start, end);

	if (nr_huge_updates)
		count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
	return pages;
}

static inline unsigned long change_pud_range(struct vm_area_struct *vma,
		pgd_t *pgd, unsigned long addr, unsigned long end,
		pgprot_t newprot, int dirty_accountable, int prot_numa)
{
	pud_t *pud;
	unsigned long next;
	unsigned long pages = 0;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud))
			continue;
		pages += change_pmd_range(vma, pud, addr, next, newprot,
				 dirty_accountable, prot_numa);
	} while (pud++, addr = next, addr != end);

	return pages;
}

static unsigned long change_protection_range(struct vm_area_struct *vma,
		unsigned long addr, unsigned long end, pgprot_t newprot,
		int dirty_accountable, int prot_numa)
{
	struct mm_struct *mm = vma->vm_mm;
	pgd_t *pgd;
	unsigned long next;
	unsigned long start = addr;
	unsigned long pages = 0;

	BUG_ON(addr >= end);
	pgd = pgd_offset(mm, addr);
	flush_cache_range(vma, addr, end);
	set_tlb_flush_pending(mm);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd))
			continue;
		pages += change_pud_range(vma, pgd, addr, next, newprot,
				 dirty_accountable, prot_numa);
	} while (pgd++, addr = next, addr != end);

	/* Only flush the TLB if we actually modified any entries: */
	if (pages)
		flush_tlb_range(vma, start, end);
	clear_tlb_flush_pending(mm);

	return pages;
}

unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
		       unsigned long end, pgprot_t newprot,
		       int dirty_accountable, int prot_numa)
{
	unsigned long pages;

	if (is_vm_hugetlb_page(vma))
		pages = hugetlb_change_protection(vma, start, end, newprot);
	else
		pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);

	return pages;
}

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;
	pgoff_t pgoff;
	int error;
	int dirty_accountable = 0;

	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. hugetlb mapping were accounted for
	 * even if read-only so there is no need to account for them here
	 */
	if (newflags & VM_WRITE) {
		if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
						VM_SHARED|VM_NORESERVE))) {
			charged = nrpages;
			if (security_vm_enough_memory_mm(mm, charged))
				return -ENOMEM;
			newflags |= VM_ACCOUNT;
		}
	}

	/*
	 * 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 = pgprot_modify(vma->vm_page_prot,
					  vm_get_page_prot(newflags));

	if (vma_wants_writenotify(vma)) {
		vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
		dirty_accountable = 1;
	}

	change_protection(vma, start, end, vma->vm_page_prot,
			  dirty_accountable, 0);

	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
	perf_event_mmap(vma);
	return 0;

fail:
	vm_unacct_memory(charged);
	return error;
}

SYSCALL_DEFINE3(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 (!arch_validate_prot(prot))
		return -EINVAL;

	reqprot = prot;
	/*
	 * Does the application expect PROT_READ to imply PROT_EXEC:
	 */
	if ((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(current->mm, start);
	error = -ENOMEM;
	if (!vma)
		goto out;
	prev = vma->vm_prev;
	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. */

		newflags = vm_flags;
		newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));

		/* newflags >> 4 shift VM_MAY% in place of VM_% */
		if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
			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;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* mm/mprotect.c
	3	*
	4	* (C) Copyright 1994 Linus Torvalds
	5	* (C) Copyright 2002 Christoph Hellwig
	6	*
046c6884	7	* Address space accounting code <alan@lxorguk.ukuu.org.uk>
1da177e4 LT	8	* (C) Copyright 2002 Red Hat Inc, All Rights Reserved
	9	*/
	10
	11	#include <linux/mm.h>
	12	#include <linux/hugetlb.h>
1da177e4 LT	13	#include <linux/shm.h>
	14	#include <linux/mman.h>
	15	#include <linux/fs.h>
	16	#include <linux/highmem.h>
	17	#include <linux/security.h>
	18	#include <linux/mempolicy.h>
	19	#include <linux/personality.h>
	20	#include <linux/syscalls.h>
0697212a CL	21	#include <linux/swap.h>
0697212a CL	22	#include <linux/swapops.h>
cddb8a5c	23	#include <linux/mmu_notifier.h>
64cdd548	24	#include <linux/migrate.h>
cdd6c482	25	#include <linux/perf_event.h>
64a9a34e	26	#include <linux/ksm.h>
1da177e4 LT	27	#include <asm/uaccess.h>
	28	#include <asm/pgtable.h>
	29	#include <asm/cacheflush.h>
	30	#include <asm/tlbflush.h>
	31
1c12c4cf VP	32	#ifndef pgprot_modify
	33	static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
	34	{
	35	return newprot;
	36	}
	37	#endif
	38
1ad9f620 MG	39	/*
	40	* For a prot_numa update we only hold mmap_sem for read so there is a
	41	* potential race with faulting where a pmd was temporarily none. This
	42	* function checks for a transhuge pmd under the appropriate lock. It
	43	* returns a pte if it was successfully locked or NULL if it raced with
	44	* a transhuge insertion.
	45	*/
	46	static pte_t lock_pte_protection(struct vm_area_struct vma, pmd_t *pmd,
	47	unsigned long addr, int prot_numa, spinlock_t **ptl)
	48	{
	49	pte_t *pte;
	50	spinlock_t *pmdl;
	51
	52	/* !prot_numa is protected by mmap_sem held for write */
	53	if (!prot_numa)
	54	return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
	55
	56	pmdl = pmd_lock(vma->vm_mm, pmd);
	57	if (unlikely(pmd_trans_huge(pmd) \|\| pmd_none(pmd))) {
	58	spin_unlock(pmdl);
	59	return NULL;
	60	}
	61
	62	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
	63	spin_unlock(pmdl);
	64	return pte;
	65	}
	66
4b10e7d5	67	static unsigned long change_pte_range(struct vm_area_struct vma, pmd_t pmd,
c1e6098b	68	unsigned long addr, unsigned long end, pgprot_t newprot,
0f19c179	69	int dirty_accountable, int prot_numa)
1da177e4	70	{
4b10e7d5	71	struct mm_struct *mm = vma->vm_mm;
0697212a	72	pte_t *pte, oldpte;
705e87c0	73	spinlock_t *ptl;
7da4d641	74	unsigned long pages = 0;
1da177e4	75
1ad9f620 MG	76	pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
	77	if (!pte)
	78	return 0;
	79
6606c3e0	80	arch_enter_lazy_mmu_mode();
1da177e4	81	do {
0697212a CL	82	oldpte = *pte;
0697212a CL	83	if (pte_present(oldpte)) {
1da177e4	84	pte_t ptent;
4b10e7d5	85	bool updated = false;
1da177e4	86
4b10e7d5	87	if (!prot_numa) {
0c5f83c2	88	ptent = ptep_modify_prot_start(mm, addr, pte);
1667918b MG	89	if (pte_numa(ptent))
1667918b MG	90	ptent = pte_mknonnuma(ptent);
4b10e7d5	91	ptent = pte_modify(ptent, newprot);
9d85d586 AK	92	/*
	93	* Avoid taking write faults for pages we
	94	* know to be dirty.
	95	*/
	96	if (dirty_accountable && pte_dirty(ptent))
	97	ptent = pte_mkwrite(ptent);
	98	ptep_modify_prot_commit(mm, addr, pte, ptent);
4b10e7d5 MG	99	updated = true;
	100	} else {
	101	struct page *page;
	102
	103	page = vm_normal_page(vma, addr, oldpte);
64a9a34e	104	if (page && !PageKsm(page)) {
1bc115d8	105	if (!pte_numa(oldpte)) {
56eecdb9	106	ptep_set_numa(mm, addr, pte);
4b10e7d5 MG	107	updated = true;
	108	}
	109	}
	110	}
4b10e7d5 MG	111	if (updated)
4b10e7d5 MG	112	pages++;
ce1744f4	113	} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
0697212a CL	114	swp_entry_t entry = pte_to_swp_entry(oldpte);
	115
	116	if (is_write_migration_entry(entry)) {
c3d16e16	117	pte_t newpte;
0697212a CL	118	/*
	119	* A protection check is difficult so
	120	* just be safe and disable write
	121	*/
	122	make_migration_entry_read(&entry);
c3d16e16 CG	123	newpte = swp_entry_to_pte(entry);
	124	if (pte_swp_soft_dirty(oldpte))
	125	newpte = pte_swp_mksoft_dirty(newpte);
	126	set_pte_at(mm, addr, pte, newpte);
e920e14c MG	127
e920e14c MG	128	pages++;
0697212a	129	}
1da177e4 LT	130	}
1da177e4 LT	131	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	132	arch_leave_lazy_mmu_mode();
705e87c0	133	pte_unmap_unlock(pte - 1, ptl);
7da4d641 PZ	134
7da4d641 PZ	135	return pages;
1da177e4 LT	136	}
1da177e4 LT	137
7d12efae AM	138	static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
	139	pud_t *pud, unsigned long addr, unsigned long end,
	140	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	141	{
1da177e4 LT	142	pmd_t *pmd;
a5338093	143	struct mm_struct *mm = vma->vm_mm;
1da177e4	144	unsigned long next;
7da4d641	145	unsigned long pages = 0;
72403b4a	146	unsigned long nr_huge_updates = 0;
a5338093	147	unsigned long mni_start = 0;
1da177e4 LT	148
	149	pmd = pmd_offset(pud, addr);
	150	do {
25cbbef1 MG	151	unsigned long this_pages;
25cbbef1 MG	152
1da177e4	153	next = pmd_addr_end(addr, end);
88a9ab6e RR	154	if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd))
88a9ab6e RR	155	continue;
a5338093 RR	156
	157	/* invoke the mmu notifier if the pmd is populated */
	158	if (!mni_start) {
	159	mni_start = addr;
	160	mmu_notifier_invalidate_range_start(mm, mni_start, end);
	161	}
	162
cd7548ab JW	163	if (pmd_trans_huge(*pmd)) {
cd7548ab JW	164	if (next - addr != HPAGE_PMD_SIZE)
e180377f	165	split_huge_page_pmd(vma, addr, pmd);
f123d74a MG	166	else {
	167	int nr_ptes = change_huge_pmd(vma, pmd, addr,
	168	newprot, prot_numa);
	169
	170	if (nr_ptes) {
72403b4a MG	171	if (nr_ptes == HPAGE_PMD_NR) {
	172	pages += HPAGE_PMD_NR;
	173	nr_huge_updates++;
	174	}
1ad9f620 MG	175
1ad9f620 MG	176	/* huge pmd was handled */
f123d74a MG	177	continue;
f123d74a MG	178	}
7da4d641	179	}
88a9ab6e	180	/* fall through, the trans huge pmd just split */
cd7548ab	181	}
25cbbef1	182	this_pages = change_pte_range(vma, pmd, addr, next, newprot,
0f19c179	183	dirty_accountable, prot_numa);
25cbbef1	184	pages += this_pages;
1da177e4	185	} while (pmd++, addr = next, addr != end);
7da4d641	186
a5338093 RR	187	if (mni_start)
	188	mmu_notifier_invalidate_range_end(mm, mni_start, end);
	189
72403b4a MG	190	if (nr_huge_updates)
72403b4a MG	191	count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
7da4d641	192	return pages;
1da177e4 LT	193	}
1da177e4 LT	194
7d12efae AM	195	static inline unsigned long change_pud_range(struct vm_area_struct *vma,
	196	pgd_t *pgd, unsigned long addr, unsigned long end,
	197	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	198	{
	199	pud_t *pud;
	200	unsigned long next;
7da4d641	201	unsigned long pages = 0;
1da177e4 LT	202
	203	pud = pud_offset(pgd, addr);
	204	do {
	205	next = pud_addr_end(addr, end);
	206	if (pud_none_or_clear_bad(pud))
	207	continue;
7da4d641	208	pages += change_pmd_range(vma, pud, addr, next, newprot,
4b10e7d5	209	dirty_accountable, prot_numa);
1da177e4	210	} while (pud++, addr = next, addr != end);
7da4d641 PZ	211
7da4d641 PZ	212	return pages;
1da177e4 LT	213	}
1da177e4 LT	214
7da4d641	215	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b	216	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	217	int dirty_accountable, int prot_numa)
1da177e4 LT	218	{
	219	struct mm_struct *mm = vma->vm_mm;
	220	pgd_t *pgd;
	221	unsigned long next;
	222	unsigned long start = addr;
7da4d641	223	unsigned long pages = 0;
1da177e4 LT	224
	225	BUG_ON(addr >= end);
	226	pgd = pgd_offset(mm, addr);
	227	flush_cache_range(vma, addr, end);
20841405	228	set_tlb_flush_pending(mm);
1da177e4 LT	229	do {
	230	next = pgd_addr_end(addr, end);
	231	if (pgd_none_or_clear_bad(pgd))
	232	continue;
7da4d641	233	pages += change_pud_range(vma, pgd, addr, next, newprot,
4b10e7d5	234	dirty_accountable, prot_numa);
1da177e4	235	} while (pgd++, addr = next, addr != end);
7da4d641	236
1233d588 IM	237	/* Only flush the TLB if we actually modified any entries: */
	238	if (pages)
	239	flush_tlb_range(vma, start, end);
20841405	240	clear_tlb_flush_pending(mm);
7da4d641 PZ	241
	242	return pages;
	243	}
	244
	245	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	246	unsigned long end, pgprot_t newprot,
4b10e7d5	247	int dirty_accountable, int prot_numa)
7da4d641	248	{
7da4d641 PZ	249	unsigned long pages;
7da4d641 PZ	250
7da4d641 PZ	251	if (is_vm_hugetlb_page(vma))
	252	pages = hugetlb_change_protection(vma, start, end, newprot);
	253	else
4b10e7d5	254	pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
7da4d641 PZ	255
7da4d641 PZ	256	return pages;
1da177e4 LT	257	}
1da177e4 LT	258
b6a2fea3	259	int
1da177e4 LT	260	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	261	unsigned long start, unsigned long end, unsigned long newflags)
	262	{
	263	struct mm_struct *mm = vma->vm_mm;
	264	unsigned long oldflags = vma->vm_flags;
	265	long nrpages = (end - start) >> PAGE_SHIFT;
	266	unsigned long charged = 0;
1da177e4 LT	267	pgoff_t pgoff;
1da177e4 LT	268	int error;
c1e6098b	269	int dirty_accountable = 0;
1da177e4 LT	270
	271	if (newflags == oldflags) {
	272	*pprev = vma;
	273	return 0;
	274	}
	275
	276	/*
	277	* If we make a private mapping writable we increase our commit;
	278	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	279	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	280	* even if read-only so there is no need to account for them here
1da177e4 LT	281	*/
1da177e4 LT	282	if (newflags & VM_WRITE) {
5a6fe125	283	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	284	VM_SHARED\|VM_NORESERVE))) {
1da177e4	285	charged = nrpages;
191c5424	286	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	287	return -ENOMEM;
	288	newflags \|= VM_ACCOUNT;
	289	}
	290	}
	291
1da177e4 LT	292	/*
	293	* First try to merge with previous and/or next vma.
	294	*/
	295	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	296	pprev = vma_merge(mm, pprev, start, end, newflags,
	297	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	298	if (*pprev) {
	299	vma = *pprev;
	300	goto success;
	301	}
	302
	303	*pprev = vma;
	304
	305	if (start != vma->vm_start) {
	306	error = split_vma(mm, vma, start, 1);
	307	if (error)
	308	goto fail;
	309	}
	310
	311	if (end != vma->vm_end) {
	312	error = split_vma(mm, vma, end, 0);
	313	if (error)
	314	goto fail;
	315	}
	316
	317	success:
	318	/*
	319	* vm_flags and vm_page_prot are protected by the mmap_sem
	320	* held in write mode.
	321	*/
	322	vma->vm_flags = newflags;
1c12c4cf VP	323	vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
	324	vm_get_page_prot(newflags));
	325
c1e6098b	326	if (vma_wants_writenotify(vma)) {
1ddd439e	327	vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
c1e6098b PZ	328	dirty_accountable = 1;
c1e6098b PZ	329	}
d08b3851	330
7d12efae AM	331	change_protection(vma, start, end, vma->vm_page_prot,
7d12efae AM	332	dirty_accountable, 0);
7da4d641	333
ab50b8ed HD	334	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	335	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
63bfd738	336	perf_event_mmap(vma);
1da177e4 LT	337	return 0;
	338
	339	fail:
	340	vm_unacct_memory(charged);
	341	return error;
	342	}
	343
6a6160a7 HC	344	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	345	unsigned long, prot)
1da177e4 LT	346	{
	347	unsigned long vm_flags, nstart, end, tmp, reqprot;
	348	struct vm_area_struct vma, prev;
	349	int error = -EINVAL;
	350	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	351	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	352	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	353	return -EINVAL;
	354
	355	if (start & ~PAGE_MASK)
	356	return -EINVAL;
	357	if (!len)
	358	return 0;
	359	len = PAGE_ALIGN(len);
	360	end = start + len;
	361	if (end <= start)
	362	return -ENOMEM;
b845f313	363	if (!arch_validate_prot(prot))
1da177e4 LT	364	return -EINVAL;
	365
	366	reqprot = prot;
	367	/*
	368	* Does the application expect PROT_READ to imply PROT_EXEC:
	369	*/
b344e05c	370	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	371	prot \|= PROT_EXEC;
	372
	373	vm_flags = calc_vm_prot_bits(prot);
	374
	375	down_write(&current->mm->mmap_sem);
	376
097d5910	377	vma = find_vma(current->mm, start);
1da177e4 LT	378	error = -ENOMEM;
	379	if (!vma)
	380	goto out;
097d5910	381	prev = vma->vm_prev;
1da177e4 LT	382	if (unlikely(grows & PROT_GROWSDOWN)) {
	383	if (vma->vm_start >= end)
	384	goto out;
	385	start = vma->vm_start;
	386	error = -EINVAL;
	387	if (!(vma->vm_flags & VM_GROWSDOWN))
	388	goto out;
7d12efae	389	} else {
1da177e4 LT	390	if (vma->vm_start > start)
	391	goto out;
	392	if (unlikely(grows & PROT_GROWSUP)) {
	393	end = vma->vm_end;
	394	error = -EINVAL;
	395	if (!(vma->vm_flags & VM_GROWSUP))
	396	goto out;
	397	}
	398	}
	399	if (start > vma->vm_start)
	400	prev = vma;
	401
	402	for (nstart = start ; ; ) {
	403	unsigned long newflags;
	404
7d12efae	405	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
1da177e4	406
7d12efae AM	407	newflags = vm_flags;
7d12efae AM	408	newflags \|= (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4	409
7e2cff42 PBG	410	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	411	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	412	error = -EACCES;
	413	goto out;
	414	}
	415
	416	error = security_file_mprotect(vma, reqprot, prot);
	417	if (error)
	418	goto out;
	419
	420	tmp = vma->vm_end;
	421	if (tmp > end)
	422	tmp = end;
	423	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	424	if (error)
	425	goto out;
	426	nstart = tmp;
	427
	428	if (nstart < prev->vm_end)
	429	nstart = prev->vm_end;
	430	if (nstart >= end)
	431	goto out;
	432
	433	vma = prev->vm_next;
	434	if (!vma \|\| vma->vm_start != nstart) {
	435	error = -ENOMEM;
	436	goto out;
	437	}
	438	}
	439	out:
	440	up_write(&current->mm->mmap_sem);
	441	return error;
	442	}