[mirror_ubuntu-jammy-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

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);
				/*
				 * 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;

				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;
					}
				}
			}
			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;
	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	60	ptent = pte_modify(ptent, newprot);
9d85d586 AK	61	/*
	62	* Avoid taking write faults for pages we
	63	* know to be dirty.
	64	*/
	65	if (dirty_accountable && pte_dirty(ptent))
	66	ptent = pte_mkwrite(ptent);
	67	ptep_modify_prot_commit(mm, addr, pte, ptent);
4b10e7d5 MG	68	updated = true;
	69	} else {
	70	struct page *page;
	71
0c5f83c2	72	ptent = *pte;
4b10e7d5	73	page = vm_normal_page(vma, addr, oldpte);
64a9a34e	74	if (page && !PageKsm(page)) {
1bc115d8	75	if (!pte_numa(oldpte)) {
4b10e7d5	76	ptent = pte_mknuma(ptent);
0c5f83c2	77	set_pte_at(mm, addr, pte, ptent);
4b10e7d5 MG	78	updated = true;
	79	}
	80	}
	81	}
4b10e7d5 MG	82	if (updated)
4b10e7d5 MG	83	pages++;
ce1744f4	84	} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
0697212a CL	85	swp_entry_t entry = pte_to_swp_entry(oldpte);
	86
	87	if (is_write_migration_entry(entry)) {
c3d16e16	88	pte_t newpte;
0697212a CL	89	/*
	90	* A protection check is difficult so
	91	* just be safe and disable write
	92	*/
	93	make_migration_entry_read(&entry);
c3d16e16 CG	94	newpte = swp_entry_to_pte(entry);
	95	if (pte_swp_soft_dirty(oldpte))
	96	newpte = pte_swp_mksoft_dirty(newpte);
	97	set_pte_at(mm, addr, pte, newpte);
e920e14c MG	98
e920e14c MG	99	pages++;
0697212a	100	}
1da177e4 LT	101	}
1da177e4 LT	102	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	103	arch_leave_lazy_mmu_mode();
705e87c0	104	pte_unmap_unlock(pte - 1, ptl);
7da4d641 PZ	105
7da4d641 PZ	106	return pages;
1da177e4 LT	107	}
1da177e4 LT	108
7d12efae AM	109	static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
	110	pud_t *pud, unsigned long addr, unsigned long end,
	111	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	112	{
	113	pmd_t *pmd;
	114	unsigned long next;
7da4d641	115	unsigned long pages = 0;
72403b4a	116	unsigned long nr_huge_updates = 0;
1da177e4 LT	117
	118	pmd = pmd_offset(pud, addr);
	119	do {
25cbbef1 MG	120	unsigned long this_pages;
25cbbef1 MG	121
1da177e4	122	next = pmd_addr_end(addr, end);
cd7548ab JW	123	if (pmd_trans_huge(*pmd)) {
cd7548ab JW	124	if (next - addr != HPAGE_PMD_SIZE)
e180377f	125	split_huge_page_pmd(vma, addr, pmd);
f123d74a MG	126	else {
	127	int nr_ptes = change_huge_pmd(vma, pmd, addr,
	128	newprot, prot_numa);
	129
	130	if (nr_ptes) {
72403b4a MG	131	if (nr_ptes == HPAGE_PMD_NR) {
	132	pages += HPAGE_PMD_NR;
	133	nr_huge_updates++;
	134	}
f123d74a MG	135	continue;
f123d74a MG	136	}
7da4d641	137	}
cd7548ab JW	138	/* fall through */
cd7548ab JW	139	}
1da177e4 LT	140	if (pmd_none_or_clear_bad(pmd))
1da177e4 LT	141	continue;
25cbbef1	142	this_pages = change_pte_range(vma, pmd, addr, next, newprot,
0f19c179	143	dirty_accountable, prot_numa);
25cbbef1	144	pages += this_pages;
1da177e4	145	} while (pmd++, addr = next, addr != end);
7da4d641	146
72403b4a MG	147	if (nr_huge_updates)
72403b4a MG	148	count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
7da4d641	149	return pages;
1da177e4 LT	150	}
1da177e4 LT	151
7d12efae AM	152	static inline unsigned long change_pud_range(struct vm_area_struct *vma,
	153	pgd_t *pgd, unsigned long addr, unsigned long end,
	154	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	155	{
	156	pud_t *pud;
	157	unsigned long next;
7da4d641	158	unsigned long pages = 0;
1da177e4 LT	159
	160	pud = pud_offset(pgd, addr);
	161	do {
	162	next = pud_addr_end(addr, end);
	163	if (pud_none_or_clear_bad(pud))
	164	continue;
7da4d641	165	pages += change_pmd_range(vma, pud, addr, next, newprot,
4b10e7d5	166	dirty_accountable, prot_numa);
1da177e4	167	} while (pud++, addr = next, addr != end);
7da4d641 PZ	168
7da4d641 PZ	169	return pages;
1da177e4 LT	170	}
1da177e4 LT	171
7da4d641	172	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b	173	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	174	int dirty_accountable, int prot_numa)
1da177e4 LT	175	{
	176	struct mm_struct *mm = vma->vm_mm;
	177	pgd_t *pgd;
	178	unsigned long next;
	179	unsigned long start = addr;
7da4d641	180	unsigned long pages = 0;
1da177e4 LT	181
	182	BUG_ON(addr >= end);
	183	pgd = pgd_offset(mm, addr);
	184	flush_cache_range(vma, addr, end);
20841405	185	set_tlb_flush_pending(mm);
1da177e4 LT	186	do {
	187	next = pgd_addr_end(addr, end);
	188	if (pgd_none_or_clear_bad(pgd))
	189	continue;
7da4d641	190	pages += change_pud_range(vma, pgd, addr, next, newprot,
4b10e7d5	191	dirty_accountable, prot_numa);
1da177e4	192	} while (pgd++, addr = next, addr != end);
7da4d641	193
1233d588 IM	194	/* Only flush the TLB if we actually modified any entries: */
	195	if (pages)
	196	flush_tlb_range(vma, start, end);
20841405	197	clear_tlb_flush_pending(mm);
7da4d641 PZ	198
	199	return pages;
	200	}
	201
	202	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	203	unsigned long end, pgprot_t newprot,
4b10e7d5	204	int dirty_accountable, int prot_numa)
7da4d641 PZ	205	{
	206	struct mm_struct *mm = vma->vm_mm;
	207	unsigned long pages;
	208
	209	mmu_notifier_invalidate_range_start(mm, start, end);
	210	if (is_vm_hugetlb_page(vma))
	211	pages = hugetlb_change_protection(vma, start, end, newprot);
	212	else
4b10e7d5	213	pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
7da4d641 PZ	214	mmu_notifier_invalidate_range_end(mm, start, end);
	215
	216	return pages;
1da177e4 LT	217	}
1da177e4 LT	218
b6a2fea3	219	int
1da177e4 LT	220	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	221	unsigned long start, unsigned long end, unsigned long newflags)
	222	{
	223	struct mm_struct *mm = vma->vm_mm;
	224	unsigned long oldflags = vma->vm_flags;
	225	long nrpages = (end - start) >> PAGE_SHIFT;
	226	unsigned long charged = 0;
1da177e4 LT	227	pgoff_t pgoff;
1da177e4 LT	228	int error;
c1e6098b	229	int dirty_accountable = 0;
1da177e4 LT	230
	231	if (newflags == oldflags) {
	232	*pprev = vma;
	233	return 0;
	234	}
	235
	236	/*
	237	* If we make a private mapping writable we increase our commit;
	238	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	239	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	240	* even if read-only so there is no need to account for them here
1da177e4 LT	241	*/
1da177e4 LT	242	if (newflags & VM_WRITE) {
5a6fe125	243	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	244	VM_SHARED\|VM_NORESERVE))) {
1da177e4	245	charged = nrpages;
191c5424	246	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	247	return -ENOMEM;
	248	newflags \|= VM_ACCOUNT;
	249	}
	250	}
	251
1da177e4 LT	252	/*
	253	* First try to merge with previous and/or next vma.
	254	*/
	255	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	256	pprev = vma_merge(mm, pprev, start, end, newflags,
	257	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	258	if (*pprev) {
	259	vma = *pprev;
	260	goto success;
	261	}
	262
	263	*pprev = vma;
	264
	265	if (start != vma->vm_start) {
	266	error = split_vma(mm, vma, start, 1);
	267	if (error)
	268	goto fail;
	269	}
	270
	271	if (end != vma->vm_end) {
	272	error = split_vma(mm, vma, end, 0);
	273	if (error)
	274	goto fail;
	275	}
	276
	277	success:
	278	/*
	279	* vm_flags and vm_page_prot are protected by the mmap_sem
	280	* held in write mode.
	281	*/
	282	vma->vm_flags = newflags;
1c12c4cf VP	283	vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
	284	vm_get_page_prot(newflags));
	285
c1e6098b	286	if (vma_wants_writenotify(vma)) {
1ddd439e	287	vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
c1e6098b PZ	288	dirty_accountable = 1;
c1e6098b PZ	289	}
d08b3851	290
7d12efae AM	291	change_protection(vma, start, end, vma->vm_page_prot,
7d12efae AM	292	dirty_accountable, 0);
7da4d641	293
ab50b8ed HD	294	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	295	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
63bfd738	296	perf_event_mmap(vma);
1da177e4 LT	297	return 0;
	298
	299	fail:
	300	vm_unacct_memory(charged);
	301	return error;
	302	}
	303
6a6160a7 HC	304	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	305	unsigned long, prot)
1da177e4 LT	306	{
	307	unsigned long vm_flags, nstart, end, tmp, reqprot;
	308	struct vm_area_struct vma, prev;
	309	int error = -EINVAL;
	310	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	311	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	312	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	313	return -EINVAL;
	314
	315	if (start & ~PAGE_MASK)
	316	return -EINVAL;
	317	if (!len)
	318	return 0;
	319	len = PAGE_ALIGN(len);
	320	end = start + len;
	321	if (end <= start)
	322	return -ENOMEM;
b845f313	323	if (!arch_validate_prot(prot))
1da177e4 LT	324	return -EINVAL;
	325
	326	reqprot = prot;
	327	/*
	328	* Does the application expect PROT_READ to imply PROT_EXEC:
	329	*/
b344e05c	330	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	331	prot \|= PROT_EXEC;
	332
	333	vm_flags = calc_vm_prot_bits(prot);
	334
	335	down_write(&current->mm->mmap_sem);
	336
097d5910	337	vma = find_vma(current->mm, start);
1da177e4 LT	338	error = -ENOMEM;
	339	if (!vma)
	340	goto out;
097d5910	341	prev = vma->vm_prev;
1da177e4 LT	342	if (unlikely(grows & PROT_GROWSDOWN)) {
	343	if (vma->vm_start >= end)
	344	goto out;
	345	start = vma->vm_start;
	346	error = -EINVAL;
	347	if (!(vma->vm_flags & VM_GROWSDOWN))
	348	goto out;
7d12efae	349	} else {
1da177e4 LT	350	if (vma->vm_start > start)
	351	goto out;
	352	if (unlikely(grows & PROT_GROWSUP)) {
	353	end = vma->vm_end;
	354	error = -EINVAL;
	355	if (!(vma->vm_flags & VM_GROWSUP))
	356	goto out;
	357	}
	358	}
	359	if (start > vma->vm_start)
	360	prev = vma;
	361
	362	for (nstart = start ; ; ) {
	363	unsigned long newflags;
	364
7d12efae	365	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
1da177e4	366
7d12efae AM	367	newflags = vm_flags;
7d12efae AM	368	newflags \|= (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4	369
7e2cff42 PBG	370	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	371	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	372	error = -EACCES;
	373	goto out;
	374	}
	375
	376	error = security_file_mprotect(vma, reqprot, prot);
	377	if (error)
	378	goto out;
	379
	380	tmp = vma->vm_end;
	381	if (tmp > end)
	382	tmp = end;
	383	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	384	if (error)
	385	goto out;
	386	nstart = tmp;
	387
	388	if (nstart < prev->vm_end)
	389	nstart = prev->vm_end;
	390	if (nstart >= end)
	391	goto out;
	392
	393	vma = prev->vm_next;
	394	if (!vma \|\| vma->vm_start != nstart) {
	395	error = -ENOMEM;
	396	goto out;
	397	}
	398	}
	399	out:
	400	up_write(&current->mm->mmap_sem);
	401	return error;
	402	}