[linux-2.6-block.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>

/*
 * 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;

			ptent = ptep_modify_prot_start(mm, addr, pte);
			ptent = pte_modify(ptent, newprot);

			/* Avoid taking write faults for known dirty pages */
			if (dirty_accountable && pte_dirty(ptent) &&
					(pte_soft_dirty(ptent) ||
					 !(vma->vm_flags & VM_SOFTDIRTY))) {
				ptent = pte_mkwrite(ptent);
			}
			ptep_modify_prot_commit(mm, addr, pte, ptent);
			pages++;
		} else if (IS_ENABLED(CONFIG_MIGRATION)) {
			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);

				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;
	dirty_accountable = vma_wants_writenotify(vma);
	vma_set_page_prot(vma);

	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
1ad9f620 MG	32	/*
	33	* For a prot_numa update we only hold mmap_sem for read so there is a
	34	* potential race with faulting where a pmd was temporarily none. This
	35	* function checks for a transhuge pmd under the appropriate lock. It
	36	* returns a pte if it was successfully locked or NULL if it raced with
	37	* a transhuge insertion.
	38	*/
	39	static pte_t lock_pte_protection(struct vm_area_struct vma, pmd_t *pmd,
	40	unsigned long addr, int prot_numa, spinlock_t **ptl)
	41	{
	42	pte_t *pte;
	43	spinlock_t *pmdl;
	44
	45	/* !prot_numa is protected by mmap_sem held for write */
	46	if (!prot_numa)
	47	return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
	48
	49	pmdl = pmd_lock(vma->vm_mm, pmd);
	50	if (unlikely(pmd_trans_huge(pmd) \|\| pmd_none(pmd))) {
	51	spin_unlock(pmdl);
	52	return NULL;
	53	}
	54
	55	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
	56	spin_unlock(pmdl);
	57	return pte;
	58	}
	59
4b10e7d5	60	static unsigned long change_pte_range(struct vm_area_struct vma, pmd_t pmd,
c1e6098b	61	unsigned long addr, unsigned long end, pgprot_t newprot,
0f19c179	62	int dirty_accountable, int prot_numa)
1da177e4	63	{
4b10e7d5	64	struct mm_struct *mm = vma->vm_mm;
0697212a	65	pte_t *pte, oldpte;
705e87c0	66	spinlock_t *ptl;
7da4d641	67	unsigned long pages = 0;
1da177e4	68
1ad9f620 MG	69	pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
	70	if (!pte)
	71	return 0;
	72
6606c3e0	73	arch_enter_lazy_mmu_mode();
1da177e4	74	do {
0697212a CL	75	oldpte = *pte;
0697212a CL	76	if (pte_present(oldpte)) {
1da177e4 LT	77	pte_t ptent;
1da177e4 LT	78
8a0516ed MG	79	ptent = ptep_modify_prot_start(mm, addr, pte);
8a0516ed MG	80	ptent = pte_modify(ptent, newprot);
4b10e7d5	81
8a0516ed MG	82	/* Avoid taking write faults for known dirty pages */
	83	if (dirty_accountable && pte_dirty(ptent) &&
	84	(pte_soft_dirty(ptent) \|\|
	85	!(vma->vm_flags & VM_SOFTDIRTY))) {
	86	ptent = pte_mkwrite(ptent);
4b10e7d5	87	}
8a0516ed MG	88	ptep_modify_prot_commit(mm, addr, pte, ptent);
8a0516ed MG	89	pages++;
0661a336	90	} else if (IS_ENABLED(CONFIG_MIGRATION)) {
0697212a CL	91	swp_entry_t entry = pte_to_swp_entry(oldpte);
	92
	93	if (is_write_migration_entry(entry)) {
c3d16e16	94	pte_t newpte;
0697212a CL	95	/*
	96	* A protection check is difficult so
	97	* just be safe and disable write
	98	*/
	99	make_migration_entry_read(&entry);
c3d16e16 CG	100	newpte = swp_entry_to_pte(entry);
	101	if (pte_swp_soft_dirty(oldpte))
	102	newpte = pte_swp_mksoft_dirty(newpte);
	103	set_pte_at(mm, addr, pte, newpte);
e920e14c MG	104
e920e14c MG	105	pages++;
0697212a	106	}
1da177e4 LT	107	}
1da177e4 LT	108	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	109	arch_leave_lazy_mmu_mode();
705e87c0	110	pte_unmap_unlock(pte - 1, ptl);
7da4d641 PZ	111
7da4d641 PZ	112	return pages;
1da177e4 LT	113	}
1da177e4 LT	114
7d12efae AM	115	static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
	116	pud_t *pud, unsigned long addr, unsigned long end,
	117	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	118	{
1da177e4 LT	119	pmd_t *pmd;
a5338093	120	struct mm_struct *mm = vma->vm_mm;
1da177e4	121	unsigned long next;
7da4d641	122	unsigned long pages = 0;
72403b4a	123	unsigned long nr_huge_updates = 0;
a5338093	124	unsigned long mni_start = 0;
1da177e4 LT	125
	126	pmd = pmd_offset(pud, addr);
	127	do {
25cbbef1 MG	128	unsigned long this_pages;
25cbbef1 MG	129
1da177e4	130	next = pmd_addr_end(addr, end);
88a9ab6e RR	131	if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd))
88a9ab6e RR	132	continue;
a5338093 RR	133
	134	/* invoke the mmu notifier if the pmd is populated */
	135	if (!mni_start) {
	136	mni_start = addr;
	137	mmu_notifier_invalidate_range_start(mm, mni_start, end);
	138	}
	139
cd7548ab JW	140	if (pmd_trans_huge(*pmd)) {
cd7548ab JW	141	if (next - addr != HPAGE_PMD_SIZE)
e180377f	142	split_huge_page_pmd(vma, addr, pmd);
f123d74a MG	143	else {
f123d74a MG	144	int nr_ptes = change_huge_pmd(vma, pmd, addr,
4d942466	145	newprot);
f123d74a MG	146
f123d74a MG	147	if (nr_ptes) {
72403b4a MG	148	if (nr_ptes == HPAGE_PMD_NR) {
	149	pages += HPAGE_PMD_NR;
	150	nr_huge_updates++;
	151	}
1ad9f620 MG	152
1ad9f620 MG	153	/* huge pmd was handled */
f123d74a MG	154	continue;
f123d74a MG	155	}
7da4d641	156	}
88a9ab6e	157	/* fall through, the trans huge pmd just split */
cd7548ab	158	}
25cbbef1	159	this_pages = change_pte_range(vma, pmd, addr, next, newprot,
0f19c179	160	dirty_accountable, prot_numa);
25cbbef1	161	pages += this_pages;
1da177e4	162	} while (pmd++, addr = next, addr != end);
7da4d641	163
a5338093 RR	164	if (mni_start)
	165	mmu_notifier_invalidate_range_end(mm, mni_start, end);
	166
72403b4a MG	167	if (nr_huge_updates)
72403b4a MG	168	count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
7da4d641	169	return pages;
1da177e4 LT	170	}
1da177e4 LT	171
7d12efae AM	172	static inline unsigned long change_pud_range(struct vm_area_struct *vma,
	173	pgd_t *pgd, unsigned long addr, unsigned long end,
	174	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	175	{
	176	pud_t *pud;
	177	unsigned long next;
7da4d641	178	unsigned long pages = 0;
1da177e4 LT	179
	180	pud = pud_offset(pgd, addr);
	181	do {
	182	next = pud_addr_end(addr, end);
	183	if (pud_none_or_clear_bad(pud))
	184	continue;
7da4d641	185	pages += change_pmd_range(vma, pud, addr, next, newprot,
4b10e7d5	186	dirty_accountable, prot_numa);
1da177e4	187	} while (pud++, addr = next, addr != end);
7da4d641 PZ	188
7da4d641 PZ	189	return pages;
1da177e4 LT	190	}
1da177e4 LT	191
7da4d641	192	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b	193	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	194	int dirty_accountable, int prot_numa)
1da177e4 LT	195	{
	196	struct mm_struct *mm = vma->vm_mm;
	197	pgd_t *pgd;
	198	unsigned long next;
	199	unsigned long start = addr;
7da4d641	200	unsigned long pages = 0;
1da177e4 LT	201
	202	BUG_ON(addr >= end);
	203	pgd = pgd_offset(mm, addr);
	204	flush_cache_range(vma, addr, end);
20841405	205	set_tlb_flush_pending(mm);
1da177e4 LT	206	do {
	207	next = pgd_addr_end(addr, end);
	208	if (pgd_none_or_clear_bad(pgd))
	209	continue;
7da4d641	210	pages += change_pud_range(vma, pgd, addr, next, newprot,
4b10e7d5	211	dirty_accountable, prot_numa);
1da177e4	212	} while (pgd++, addr = next, addr != end);
7da4d641	213
1233d588 IM	214	/* Only flush the TLB if we actually modified any entries: */
	215	if (pages)
	216	flush_tlb_range(vma, start, end);
20841405	217	clear_tlb_flush_pending(mm);
7da4d641 PZ	218
	219	return pages;
	220	}
	221
	222	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	223	unsigned long end, pgprot_t newprot,
4b10e7d5	224	int dirty_accountable, int prot_numa)
7da4d641	225	{
7da4d641 PZ	226	unsigned long pages;
7da4d641 PZ	227
7da4d641 PZ	228	if (is_vm_hugetlb_page(vma))
	229	pages = hugetlb_change_protection(vma, start, end, newprot);
	230	else
4b10e7d5	231	pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
7da4d641 PZ	232
7da4d641 PZ	233	return pages;
1da177e4 LT	234	}
1da177e4 LT	235
b6a2fea3	236	int
1da177e4 LT	237	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	238	unsigned long start, unsigned long end, unsigned long newflags)
	239	{
	240	struct mm_struct *mm = vma->vm_mm;
	241	unsigned long oldflags = vma->vm_flags;
	242	long nrpages = (end - start) >> PAGE_SHIFT;
	243	unsigned long charged = 0;
1da177e4 LT	244	pgoff_t pgoff;
1da177e4 LT	245	int error;
c1e6098b	246	int dirty_accountable = 0;
1da177e4 LT	247
	248	if (newflags == oldflags) {
	249	*pprev = vma;
	250	return 0;
	251	}
	252
	253	/*
	254	* If we make a private mapping writable we increase our commit;
	255	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	256	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	257	* even if read-only so there is no need to account for them here
1da177e4 LT	258	*/
1da177e4 LT	259	if (newflags & VM_WRITE) {
5a6fe125	260	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	261	VM_SHARED\|VM_NORESERVE))) {
1da177e4	262	charged = nrpages;
191c5424	263	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	264	return -ENOMEM;
	265	newflags \|= VM_ACCOUNT;
	266	}
	267	}
	268
1da177e4 LT	269	/*
	270	* First try to merge with previous and/or next vma.
	271	*/
	272	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	273	pprev = vma_merge(mm, pprev, start, end, newflags,
	274	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	275	if (*pprev) {
	276	vma = *pprev;
	277	goto success;
	278	}
	279
	280	*pprev = vma;
	281
	282	if (start != vma->vm_start) {
	283	error = split_vma(mm, vma, start, 1);
	284	if (error)
	285	goto fail;
	286	}
	287
	288	if (end != vma->vm_end) {
	289	error = split_vma(mm, vma, end, 0);
	290	if (error)
	291	goto fail;
	292	}
	293
	294	success:
	295	/*
	296	* vm_flags and vm_page_prot are protected by the mmap_sem
	297	* held in write mode.
	298	*/
	299	vma->vm_flags = newflags;
64e45507 PF	300	dirty_accountable = vma_wants_writenotify(vma);
64e45507 PF	301	vma_set_page_prot(vma);
d08b3851	302
7d12efae AM	303	change_protection(vma, start, end, vma->vm_page_prot,
7d12efae AM	304	dirty_accountable, 0);
7da4d641	305
ab50b8ed HD	306	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	307	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
63bfd738	308	perf_event_mmap(vma);
1da177e4 LT	309	return 0;
	310
	311	fail:
	312	vm_unacct_memory(charged);
	313	return error;
	314	}
	315
6a6160a7 HC	316	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	317	unsigned long, prot)
1da177e4 LT	318	{
	319	unsigned long vm_flags, nstart, end, tmp, reqprot;
	320	struct vm_area_struct vma, prev;
	321	int error = -EINVAL;
	322	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	323	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	324	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	325	return -EINVAL;
	326
	327	if (start & ~PAGE_MASK)
	328	return -EINVAL;
	329	if (!len)
	330	return 0;
	331	len = PAGE_ALIGN(len);
	332	end = start + len;
	333	if (end <= start)
	334	return -ENOMEM;
b845f313	335	if (!arch_validate_prot(prot))
1da177e4 LT	336	return -EINVAL;
	337
	338	reqprot = prot;
	339	/*
	340	* Does the application expect PROT_READ to imply PROT_EXEC:
	341	*/
b344e05c	342	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	343	prot \|= PROT_EXEC;
	344
	345	vm_flags = calc_vm_prot_bits(prot);
	346
	347	down_write(&current->mm->mmap_sem);
	348
097d5910	349	vma = find_vma(current->mm, start);
1da177e4 LT	350	error = -ENOMEM;
	351	if (!vma)
	352	goto out;
097d5910	353	prev = vma->vm_prev;
1da177e4 LT	354	if (unlikely(grows & PROT_GROWSDOWN)) {
	355	if (vma->vm_start >= end)
	356	goto out;
	357	start = vma->vm_start;
	358	error = -EINVAL;
	359	if (!(vma->vm_flags & VM_GROWSDOWN))
	360	goto out;
7d12efae	361	} else {
1da177e4 LT	362	if (vma->vm_start > start)
	363	goto out;
	364	if (unlikely(grows & PROT_GROWSUP)) {
	365	end = vma->vm_end;
	366	error = -EINVAL;
	367	if (!(vma->vm_flags & VM_GROWSUP))
	368	goto out;
	369	}
	370	}
	371	if (start > vma->vm_start)
	372	prev = vma;
	373
	374	for (nstart = start ; ; ) {
	375	unsigned long newflags;
	376
7d12efae	377	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
1da177e4	378
7d12efae AM	379	newflags = vm_flags;
7d12efae AM	380	newflags \|= (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4	381
7e2cff42 PBG	382	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	383	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	384	error = -EACCES;
	385	goto out;
	386	}
	387
	388	error = security_file_mprotect(vma, reqprot, prot);
	389	if (error)
	390	goto out;
	391
	392	tmp = vma->vm_end;
	393	if (tmp > end)
	394	tmp = end;
	395	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	396	if (error)
	397	goto out;
	398	nstart = tmp;
	399
	400	if (nstart < prev->vm_end)
	401	nstart = prev->vm_end;
	402	if (nstart >= end)
	403	goto out;
	404
	405	vma = prev->vm_next;
	406	if (!vma \|\| vma->vm_start != nstart) {
	407	error = -ENOMEM;
	408	goto out;
	409	}
	410	}
	411	out:
	412	up_write(&current->mm->mmap_sem);
	413	return error;
	414	}