[deliverable/linux.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

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 = pte_offset_map_lock(mm, pmd, addr, &ptl);
	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);
				updated = true;
			} else {
				struct page *page;

				ptent = *pte;
				page = vm_normal_page(vma, addr, oldpte);
				if (page && !PageKsm(page)) {
					if (!pte_numa(oldpte)) {
						ptent = pte_mknuma(ptent);
						set_pte_at(mm, addr, pte, ptent);
						updated = true;
					}
				}
			}

			/*
			 * Avoid taking write faults for pages we know to be
			 * dirty.
			 */
			if (dirty_accountable && pte_dirty(ptent)) {
				ptent = pte_mkwrite(ptent);
				updated = true;
			}

			if (updated)
				pages++;

			/* Only !prot_numa always clears the pte */
			if (!prot_numa)
				ptep_modify_prot_commit(mm, addr, pte, ptent);
		} 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;
	unsigned long next;
	unsigned long pages = 0;
	unsigned long nr_huge_updates = 0;

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

		next = pmd_addr_end(addr, 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++;
					}
					continue;
				}
			}
			/* fall through */
		}
		if (pmd_none_or_clear_bad(pmd))
			continue;
		this_pages = change_pte_range(vma, pmd, addr, next, newprot,
				 dirty_accountable, prot_numa);
		pages += this_pages;
	} while (pmd++, addr = next, addr != 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)
{
	struct mm_struct *mm = vma->vm_mm;
	unsigned long pages;

	mmu_notifier_invalidate_range_start(mm, start, end);
	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);
	mmu_notifier_invalidate_range_end(mm, start, end);

	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
4b10e7d5	39	static unsigned long change_pte_range(struct vm_area_struct vma, pmd_t pmd,
c1e6098b	40	unsigned long addr, unsigned long end, pgprot_t newprot,
0f19c179	41	int dirty_accountable, int prot_numa)
1da177e4	42	{
4b10e7d5	43	struct mm_struct *mm = vma->vm_mm;
0697212a	44	pte_t *pte, oldpte;
705e87c0	45	spinlock_t *ptl;
7da4d641	46	unsigned long pages = 0;
1da177e4	47
705e87c0	48	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
6606c3e0	49	arch_enter_lazy_mmu_mode();
1da177e4	50	do {
0697212a CL	51	oldpte = *pte;
0697212a CL	52	if (pte_present(oldpte)) {
1da177e4	53	pte_t ptent;
4b10e7d5	54	bool updated = false;
1da177e4	55
4b10e7d5	56	if (!prot_numa) {
0c5f83c2	57	ptent = ptep_modify_prot_start(mm, addr, pte);
1667918b MG	58	if (pte_numa(ptent))
1667918b MG	59	ptent = pte_mknonnuma(ptent);
4b10e7d5 MG	60	ptent = pte_modify(ptent, newprot);
	61	updated = true;
	62	} else {
	63	struct page *page;
	64
0c5f83c2	65	ptent = *pte;
4b10e7d5	66	page = vm_normal_page(vma, addr, oldpte);
64a9a34e	67	if (page && !PageKsm(page)) {
1bc115d8	68	if (!pte_numa(oldpte)) {
4b10e7d5	69	ptent = pte_mknuma(ptent);
0c5f83c2	70	set_pte_at(mm, addr, pte, ptent);
4b10e7d5 MG	71	updated = true;
	72	}
	73	}
	74	}
1ea0704e	75
c1e6098b PZ	76	/*
	77	* Avoid taking write faults for pages we know to be
	78	* dirty.
	79	*/
4b10e7d5	80	if (dirty_accountable && pte_dirty(ptent)) {
c1e6098b	81	ptent = pte_mkwrite(ptent);
4b10e7d5 MG	82	updated = true;
4b10e7d5 MG	83	}
1ea0704e	84
4b10e7d5 MG	85	if (updated)
4b10e7d5 MG	86	pages++;
0c5f83c2 MG	87
	88	/* Only !prot_numa always clears the pte */
	89	if (!prot_numa)
	90	ptep_modify_prot_commit(mm, addr, pte, ptent);
ce1744f4	91	} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
0697212a CL	92	swp_entry_t entry = pte_to_swp_entry(oldpte);
	93
	94	if (is_write_migration_entry(entry)) {
c3d16e16	95	pte_t newpte;
0697212a CL	96	/*
	97	* A protection check is difficult so
	98	* just be safe and disable write
	99	*/
	100	make_migration_entry_read(&entry);
c3d16e16 CG	101	newpte = swp_entry_to_pte(entry);
	102	if (pte_swp_soft_dirty(oldpte))
	103	newpte = pte_swp_mksoft_dirty(newpte);
	104	set_pte_at(mm, addr, pte, newpte);
e920e14c MG	105
e920e14c MG	106	pages++;
0697212a	107	}
1da177e4 LT	108	}
1da177e4 LT	109	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	110	arch_leave_lazy_mmu_mode();
705e87c0	111	pte_unmap_unlock(pte - 1, ptl);
7da4d641 PZ	112
7da4d641 PZ	113	return pages;
1da177e4 LT	114	}
1da177e4 LT	115
7d12efae AM	116	static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
	117	pud_t *pud, unsigned long addr, unsigned long end,
	118	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	119	{
	120	pmd_t *pmd;
	121	unsigned long next;
7da4d641	122	unsigned long pages = 0;
72403b4a	123	unsigned long nr_huge_updates = 0;
1da177e4 LT	124
	125	pmd = pmd_offset(pud, addr);
	126	do {
25cbbef1 MG	127	unsigned long this_pages;
25cbbef1 MG	128
1da177e4	129	next = pmd_addr_end(addr, end);
cd7548ab JW	130	if (pmd_trans_huge(*pmd)) {
cd7548ab JW	131	if (next - addr != HPAGE_PMD_SIZE)
e180377f	132	split_huge_page_pmd(vma, addr, pmd);
f123d74a MG	133	else {
	134	int nr_ptes = change_huge_pmd(vma, pmd, addr,
	135	newprot, prot_numa);
	136
	137	if (nr_ptes) {
72403b4a MG	138	if (nr_ptes == HPAGE_PMD_NR) {
	139	pages += HPAGE_PMD_NR;
	140	nr_huge_updates++;
	141	}
f123d74a MG	142	continue;
f123d74a MG	143	}
7da4d641	144	}
cd7548ab JW	145	/* fall through */
cd7548ab JW	146	}
1da177e4 LT	147	if (pmd_none_or_clear_bad(pmd))
1da177e4 LT	148	continue;
25cbbef1	149	this_pages = change_pte_range(vma, pmd, addr, next, newprot,
0f19c179	150	dirty_accountable, prot_numa);
25cbbef1	151	pages += this_pages;
1da177e4	152	} while (pmd++, addr = next, addr != end);
7da4d641	153
72403b4a MG	154	if (nr_huge_updates)
72403b4a MG	155	count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
7da4d641	156	return pages;
1da177e4 LT	157	}
1da177e4 LT	158
7d12efae AM	159	static inline unsigned long change_pud_range(struct vm_area_struct *vma,
	160	pgd_t *pgd, unsigned long addr, unsigned long end,
	161	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	162	{
	163	pud_t *pud;
	164	unsigned long next;
7da4d641	165	unsigned long pages = 0;
1da177e4 LT	166
	167	pud = pud_offset(pgd, addr);
	168	do {
	169	next = pud_addr_end(addr, end);
	170	if (pud_none_or_clear_bad(pud))
	171	continue;
7da4d641	172	pages += change_pmd_range(vma, pud, addr, next, newprot,
4b10e7d5	173	dirty_accountable, prot_numa);
1da177e4	174	} while (pud++, addr = next, addr != end);
7da4d641 PZ	175
7da4d641 PZ	176	return pages;
1da177e4 LT	177	}
1da177e4 LT	178
7da4d641	179	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b	180	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	181	int dirty_accountable, int prot_numa)
1da177e4 LT	182	{
	183	struct mm_struct *mm = vma->vm_mm;
	184	pgd_t *pgd;
	185	unsigned long next;
	186	unsigned long start = addr;
7da4d641	187	unsigned long pages = 0;
1da177e4 LT	188
	189	BUG_ON(addr >= end);
	190	pgd = pgd_offset(mm, addr);
	191	flush_cache_range(vma, addr, end);
20841405	192	set_tlb_flush_pending(mm);
1da177e4 LT	193	do {
	194	next = pgd_addr_end(addr, end);
	195	if (pgd_none_or_clear_bad(pgd))
	196	continue;
7da4d641	197	pages += change_pud_range(vma, pgd, addr, next, newprot,
4b10e7d5	198	dirty_accountable, prot_numa);
1da177e4	199	} while (pgd++, addr = next, addr != end);
7da4d641	200
1233d588 IM	201	/* Only flush the TLB if we actually modified any entries: */
	202	if (pages)
	203	flush_tlb_range(vma, start, end);
20841405	204	clear_tlb_flush_pending(mm);
7da4d641 PZ	205
	206	return pages;
	207	}
	208
	209	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	210	unsigned long end, pgprot_t newprot,
4b10e7d5	211	int dirty_accountable, int prot_numa)
7da4d641 PZ	212	{
	213	struct mm_struct *mm = vma->vm_mm;
	214	unsigned long pages;
	215
	216	mmu_notifier_invalidate_range_start(mm, start, end);
	217	if (is_vm_hugetlb_page(vma))
	218	pages = hugetlb_change_protection(vma, start, end, newprot);
	219	else
4b10e7d5	220	pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
7da4d641 PZ	221	mmu_notifier_invalidate_range_end(mm, start, end);
	222
	223	return pages;
1da177e4 LT	224	}
1da177e4 LT	225
b6a2fea3	226	int
1da177e4 LT	227	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	228	unsigned long start, unsigned long end, unsigned long newflags)
	229	{
	230	struct mm_struct *mm = vma->vm_mm;
	231	unsigned long oldflags = vma->vm_flags;
	232	long nrpages = (end - start) >> PAGE_SHIFT;
	233	unsigned long charged = 0;
1da177e4 LT	234	pgoff_t pgoff;
1da177e4 LT	235	int error;
c1e6098b	236	int dirty_accountable = 0;
1da177e4 LT	237
	238	if (newflags == oldflags) {
	239	*pprev = vma;
	240	return 0;
	241	}
	242
	243	/*
	244	* If we make a private mapping writable we increase our commit;
	245	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	246	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	247	* even if read-only so there is no need to account for them here
1da177e4 LT	248	*/
1da177e4 LT	249	if (newflags & VM_WRITE) {
5a6fe125	250	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	251	VM_SHARED\|VM_NORESERVE))) {
1da177e4	252	charged = nrpages;
191c5424	253	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	254	return -ENOMEM;
	255	newflags \|= VM_ACCOUNT;
	256	}
	257	}
	258
1da177e4 LT	259	/*
	260	* First try to merge with previous and/or next vma.
	261	*/
	262	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	263	pprev = vma_merge(mm, pprev, start, end, newflags,
	264	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	265	if (*pprev) {
	266	vma = *pprev;
	267	goto success;
	268	}
	269
	270	*pprev = vma;
	271
	272	if (start != vma->vm_start) {
	273	error = split_vma(mm, vma, start, 1);
	274	if (error)
	275	goto fail;
	276	}
	277
	278	if (end != vma->vm_end) {
	279	error = split_vma(mm, vma, end, 0);
	280	if (error)
	281	goto fail;
	282	}
	283
	284	success:
	285	/*
	286	* vm_flags and vm_page_prot are protected by the mmap_sem
	287	* held in write mode.
	288	*/
	289	vma->vm_flags = newflags;
1c12c4cf VP	290	vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
	291	vm_get_page_prot(newflags));
	292
c1e6098b	293	if (vma_wants_writenotify(vma)) {
1ddd439e	294	vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
c1e6098b PZ	295	dirty_accountable = 1;
c1e6098b PZ	296	}
d08b3851	297
7d12efae AM	298	change_protection(vma, start, end, vma->vm_page_prot,
7d12efae AM	299	dirty_accountable, 0);
7da4d641	300
ab50b8ed HD	301	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	302	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
63bfd738	303	perf_event_mmap(vma);
1da177e4 LT	304	return 0;
	305
	306	fail:
	307	vm_unacct_memory(charged);
	308	return error;
	309	}
	310
6a6160a7 HC	311	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	312	unsigned long, prot)
1da177e4 LT	313	{
	314	unsigned long vm_flags, nstart, end, tmp, reqprot;
	315	struct vm_area_struct vma, prev;
	316	int error = -EINVAL;
	317	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	318	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	319	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	320	return -EINVAL;
	321
	322	if (start & ~PAGE_MASK)
	323	return -EINVAL;
	324	if (!len)
	325	return 0;
	326	len = PAGE_ALIGN(len);
	327	end = start + len;
	328	if (end <= start)
	329	return -ENOMEM;
b845f313	330	if (!arch_validate_prot(prot))
1da177e4 LT	331	return -EINVAL;
	332
	333	reqprot = prot;
	334	/*
	335	* Does the application expect PROT_READ to imply PROT_EXEC:
	336	*/
b344e05c	337	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	338	prot \|= PROT_EXEC;
	339
	340	vm_flags = calc_vm_prot_bits(prot);
	341
	342	down_write(&current->mm->mmap_sem);
	343
097d5910	344	vma = find_vma(current->mm, start);
1da177e4 LT	345	error = -ENOMEM;
	346	if (!vma)
	347	goto out;
097d5910	348	prev = vma->vm_prev;
1da177e4 LT	349	if (unlikely(grows & PROT_GROWSDOWN)) {
	350	if (vma->vm_start >= end)
	351	goto out;
	352	start = vma->vm_start;
	353	error = -EINVAL;
	354	if (!(vma->vm_flags & VM_GROWSDOWN))
	355	goto out;
7d12efae	356	} else {
1da177e4 LT	357	if (vma->vm_start > start)
	358	goto out;
	359	if (unlikely(grows & PROT_GROWSUP)) {
	360	end = vma->vm_end;
	361	error = -EINVAL;
	362	if (!(vma->vm_flags & VM_GROWSUP))
	363	goto out;
	364	}
	365	}
	366	if (start > vma->vm_start)
	367	prev = vma;
	368
	369	for (nstart = start ; ; ) {
	370	unsigned long newflags;
	371
7d12efae	372	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
1da177e4	373
7d12efae AM	374	newflags = vm_flags;
7d12efae AM	375	newflags \|= (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4	376
7e2cff42 PBG	377	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	378	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	379	error = -EACCES;
	380	goto out;
	381	}
	382
	383	error = security_file_mprotect(vma, reqprot, prot);
	384	if (error)
	385	goto out;
	386
	387	tmp = vma->vm_end;
	388	if (tmp > end)
	389	tmp = end;
	390	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	391	if (error)
	392	goto out;
	393	nstart = tmp;
	394
	395	if (nstart < prev->vm_end)
	396	nstart = prev->vm_end;
	397	if (nstart >= end)
	398	goto out;
	399
	400	vma = prev->vm_next;
	401	if (!vma \|\| vma->vm_start != nstart) {
	402	error = -ENOMEM;
	403	goto out;
	404	}
	405	}
	406	out:
	407	up_write(&current->mm->mmap_sem);
	408	return error;
	409	}