[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 <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, bool *ret_all_same_node)
{
	struct mm_struct *mm = vma->vm_mm;
	pte_t *pte, oldpte;
	spinlock_t *ptl;
	unsigned long pages = 0;
	bool all_same_node = true;
	int last_nid = -1;

	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;

			ptent = ptep_modify_prot_start(mm, addr, pte);
			if (!prot_numa) {
				ptent = pte_modify(ptent, newprot);
				updated = true;
			} else {
				struct page *page;

				page = vm_normal_page(vma, addr, oldpte);
				if (page) {
					int this_nid = page_to_nid(page);
					if (last_nid == -1)
						last_nid = this_nid;
					if (last_nid != this_nid)
						all_same_node = false;

					/* only check non-shared pages */
					if (!pte_numa(oldpte) &&
					    page_mapcount(page) == 1) {
						ptent = pte_mknuma(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++;
			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);

	*ret_all_same_node = all_same_node;
	return pages;
}

#ifdef CONFIG_NUMA_BALANCING
static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
				       pmd_t *pmd)
{
	spin_lock(&mm->page_table_lock);
	set_pmd_at(mm, addr & PMD_MASK, pmd, pmd_mknuma(*pmd));
	spin_unlock(&mm->page_table_lock);
}
#else
static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
				       pmd_t *pmd)
{
	BUG();
}
#endif /* CONFIG_NUMA_BALANCING */

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;
	bool all_same_node;

	pmd = pmd_offset(pud, addr);
	do {
		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 if (change_huge_pmd(vma, pmd, addr, newprot,
						 prot_numa)) {
				pages += HPAGE_PMD_NR;
				continue;
			}
			/* fall through */
		}
		if (pmd_none_or_clear_bad(pmd))
			continue;
		pages += change_pte_range(vma, pmd, addr, next, newprot,
				 dirty_accountable, prot_numa, &all_same_node);

		/*
		 * If we are changing protections for NUMA hinting faults then
		 * set pmd_numa if the examined pages were all on the same
		 * node. This allows a regular PMD to be handled as one fault
		 * and effectively batches the taking of the PTL
		 */
		if (prot_numa && all_same_node)
			change_pmd_protnuma(vma->vm_mm, addr, pmd);
	} while (pmd++, addr = next, addr != end);

	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);
	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);

	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>
1da177e4 LT	26	#include <asm/uaccess.h>
	27	#include <asm/pgtable.h>
	28	#include <asm/cacheflush.h>
	29	#include <asm/tlbflush.h>
	30
1c12c4cf VP	31	#ifndef pgprot_modify
	32	static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
	33	{
	34	return newprot;
	35	}
	36	#endif
	37
4b10e7d5	38	static unsigned long change_pte_range(struct vm_area_struct vma, pmd_t pmd,
c1e6098b	39	unsigned long addr, unsigned long end, pgprot_t newprot,
9532fec1	40	int dirty_accountable, int prot_numa, bool *ret_all_same_node)
1da177e4	41	{
4b10e7d5	42	struct mm_struct *mm = vma->vm_mm;
0697212a	43	pte_t *pte, oldpte;
705e87c0	44	spinlock_t *ptl;
7da4d641	45	unsigned long pages = 0;
9532fec1 MG	46	bool all_same_node = true;
9532fec1 MG	47	int last_nid = -1;
1da177e4	48
705e87c0	49	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
6606c3e0	50	arch_enter_lazy_mmu_mode();
1da177e4	51	do {
0697212a CL	52	oldpte = *pte;
0697212a CL	53	if (pte_present(oldpte)) {
1da177e4	54	pte_t ptent;
4b10e7d5	55	bool updated = false;
1da177e4	56
1ea0704e	57	ptent = ptep_modify_prot_start(mm, addr, pte);
4b10e7d5 MG	58	if (!prot_numa) {
	59	ptent = pte_modify(ptent, newprot);
	60	updated = true;
	61	} else {
	62	struct page *page;
	63
	64	page = vm_normal_page(vma, addr, oldpte);
	65	if (page) {
9532fec1 MG	66	int this_nid = page_to_nid(page);
	67	if (last_nid == -1)
	68	last_nid = this_nid;
	69	if (last_nid != this_nid)
	70	all_same_node = false;
	71
4b10e7d5 MG	72	/* only check non-shared pages */
	73	if (!pte_numa(oldpte) &&
	74	page_mapcount(page) == 1) {
	75	ptent = pte_mknuma(ptent);
	76	updated = true;
	77	}
	78	}
	79	}
1ea0704e	80
c1e6098b PZ	81	/*
	82	* Avoid taking write faults for pages we know to be
	83	* dirty.
	84	*/
4b10e7d5	85	if (dirty_accountable && pte_dirty(ptent)) {
c1e6098b	86	ptent = pte_mkwrite(ptent);
4b10e7d5 MG	87	updated = true;
4b10e7d5 MG	88	}
1ea0704e	89
4b10e7d5 MG	90	if (updated)
4b10e7d5 MG	91	pages++;
1ea0704e	92	ptep_modify_prot_commit(mm, addr, pte, ptent);
ce1744f4	93	} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
0697212a CL	94	swp_entry_t entry = pte_to_swp_entry(oldpte);
	95
	96	if (is_write_migration_entry(entry)) {
c3d16e16	97	pte_t newpte;
0697212a CL	98	/*
	99	* A protection check is difficult so
	100	* just be safe and disable write
	101	*/
	102	make_migration_entry_read(&entry);
c3d16e16 CG	103	newpte = swp_entry_to_pte(entry);
	104	if (pte_swp_soft_dirty(oldpte))
	105	newpte = pte_swp_mksoft_dirty(newpte);
	106	set_pte_at(mm, addr, pte, newpte);
0697212a	107	}
7da4d641	108	pages++;
1da177e4 LT	109	}
1da177e4 LT	110	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	111	arch_leave_lazy_mmu_mode();
705e87c0	112	pte_unmap_unlock(pte - 1, ptl);
7da4d641	113
9532fec1	114	*ret_all_same_node = all_same_node;
7da4d641	115	return pages;
1da177e4 LT	116	}
1da177e4 LT	117
4b10e7d5 MG	118	#ifdef CONFIG_NUMA_BALANCING
4b10e7d5 MG	119	static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
7d12efae	120	pmd_t *pmd)
4b10e7d5 MG	121	{
	122	spin_lock(&mm->page_table_lock);
	123	set_pmd_at(mm, addr & PMD_MASK, pmd, pmd_mknuma(*pmd));
	124	spin_unlock(&mm->page_table_lock);
	125	}
	126	#else
	127	static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
7d12efae	128	pmd_t *pmd)
4b10e7d5 MG	129	{
4b10e7d5 MG	130	BUG();
1da177e4	131	}
4b10e7d5	132	#endif /* CONFIG_NUMA_BALANCING */
1da177e4	133
7d12efae AM	134	static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
	135	pud_t *pud, unsigned long addr, unsigned long end,
	136	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	137	{
	138	pmd_t *pmd;
	139	unsigned long next;
7da4d641	140	unsigned long pages = 0;
9532fec1	141	bool all_same_node;
1da177e4 LT	142
	143	pmd = pmd_offset(pud, addr);
	144	do {
	145	next = pmd_addr_end(addr, end);
cd7548ab JW	146	if (pmd_trans_huge(*pmd)) {
cd7548ab JW	147	if (next - addr != HPAGE_PMD_SIZE)
e180377f	148	split_huge_page_pmd(vma, addr, pmd);
7d12efae AM	149	else if (change_huge_pmd(vma, pmd, addr, newprot,
7d12efae AM	150	prot_numa)) {
7da4d641	151	pages += HPAGE_PMD_NR;
cd7548ab	152	continue;
7da4d641	153	}
cd7548ab JW	154	/* fall through */
cd7548ab JW	155	}
1da177e4 LT	156	if (pmd_none_or_clear_bad(pmd))
1da177e4 LT	157	continue;
4b10e7d5	158	pages += change_pte_range(vma, pmd, addr, next, newprot,
9532fec1	159	dirty_accountable, prot_numa, &all_same_node);
4b10e7d5	160
9532fec1 MG	161	/*
	162	* If we are changing protections for NUMA hinting faults then
	163	* set pmd_numa if the examined pages were all on the same
	164	* node. This allows a regular PMD to be handled as one fault
	165	* and effectively batches the taking of the PTL
	166	*/
	167	if (prot_numa && all_same_node)
4b10e7d5	168	change_pmd_protnuma(vma->vm_mm, addr, pmd);
1da177e4	169	} while (pmd++, addr = next, addr != end);
7da4d641 PZ	170
7da4d641 PZ	171	return pages;
1da177e4 LT	172	}
1da177e4 LT	173
7d12efae AM	174	static inline unsigned long change_pud_range(struct vm_area_struct *vma,
	175	pgd_t *pgd, unsigned long addr, unsigned long end,
	176	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	177	{
	178	pud_t *pud;
	179	unsigned long next;
7da4d641	180	unsigned long pages = 0;
1da177e4 LT	181
	182	pud = pud_offset(pgd, addr);
	183	do {
	184	next = pud_addr_end(addr, end);
	185	if (pud_none_or_clear_bad(pud))
	186	continue;
7da4d641	187	pages += change_pmd_range(vma, pud, addr, next, newprot,
4b10e7d5	188	dirty_accountable, prot_numa);
1da177e4	189	} while (pud++, addr = next, addr != end);
7da4d641 PZ	190
7da4d641 PZ	191	return pages;
1da177e4 LT	192	}
1da177e4 LT	193
7da4d641	194	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b	195	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	196	int dirty_accountable, int prot_numa)
1da177e4 LT	197	{
	198	struct mm_struct *mm = vma->vm_mm;
	199	pgd_t *pgd;
	200	unsigned long next;
	201	unsigned long start = addr;
7da4d641	202	unsigned long pages = 0;
1da177e4 LT	203
	204	BUG_ON(addr >= end);
	205	pgd = pgd_offset(mm, addr);
	206	flush_cache_range(vma, addr, end);
1da177e4 LT	207	do {
	208	next = pgd_addr_end(addr, end);
	209	if (pgd_none_or_clear_bad(pgd))
	210	continue;
7da4d641	211	pages += change_pud_range(vma, pgd, addr, next, newprot,
4b10e7d5	212	dirty_accountable, prot_numa);
1da177e4	213	} while (pgd++, addr = next, addr != end);
7da4d641	214
1233d588 IM	215	/* Only flush the TLB if we actually modified any entries: */
	216	if (pages)
	217	flush_tlb_range(vma, start, end);
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 PZ	225	{
	226	struct mm_struct *mm = vma->vm_mm;
	227	unsigned long pages;
	228
	229	mmu_notifier_invalidate_range_start(mm, start, end);
	230	if (is_vm_hugetlb_page(vma))
	231	pages = hugetlb_change_protection(vma, start, end, newprot);
	232	else
4b10e7d5	233	pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
7da4d641 PZ	234	mmu_notifier_invalidate_range_end(mm, start, end);
	235
	236	return pages;
1da177e4 LT	237	}
1da177e4 LT	238
b6a2fea3	239	int
1da177e4 LT	240	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	241	unsigned long start, unsigned long end, unsigned long newflags)
	242	{
	243	struct mm_struct *mm = vma->vm_mm;
	244	unsigned long oldflags = vma->vm_flags;
	245	long nrpages = (end - start) >> PAGE_SHIFT;
	246	unsigned long charged = 0;
1da177e4 LT	247	pgoff_t pgoff;
1da177e4 LT	248	int error;
c1e6098b	249	int dirty_accountable = 0;
1da177e4 LT	250
	251	if (newflags == oldflags) {
	252	*pprev = vma;
	253	return 0;
	254	}
	255
	256	/*
	257	* If we make a private mapping writable we increase our commit;
	258	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	259	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	260	* even if read-only so there is no need to account for them here
1da177e4 LT	261	*/
1da177e4 LT	262	if (newflags & VM_WRITE) {
5a6fe125	263	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	264	VM_SHARED\|VM_NORESERVE))) {
1da177e4	265	charged = nrpages;
191c5424	266	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	267	return -ENOMEM;
	268	newflags \|= VM_ACCOUNT;
	269	}
	270	}
	271
1da177e4 LT	272	/*
	273	* First try to merge with previous and/or next vma.
	274	*/
	275	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	276	pprev = vma_merge(mm, pprev, start, end, newflags,
	277	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	278	if (*pprev) {
	279	vma = *pprev;
	280	goto success;
	281	}
	282
	283	*pprev = vma;
	284
	285	if (start != vma->vm_start) {
	286	error = split_vma(mm, vma, start, 1);
	287	if (error)
	288	goto fail;
	289	}
	290
	291	if (end != vma->vm_end) {
	292	error = split_vma(mm, vma, end, 0);
	293	if (error)
	294	goto fail;
	295	}
	296
	297	success:
	298	/*
	299	* vm_flags and vm_page_prot are protected by the mmap_sem
	300	* held in write mode.
	301	*/
	302	vma->vm_flags = newflags;
1c12c4cf VP	303	vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
	304	vm_get_page_prot(newflags));
	305
c1e6098b	306	if (vma_wants_writenotify(vma)) {
1ddd439e	307	vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
c1e6098b PZ	308	dirty_accountable = 1;
c1e6098b PZ	309	}
d08b3851	310
7d12efae AM	311	change_protection(vma, start, end, vma->vm_page_prot,
7d12efae AM	312	dirty_accountable, 0);
7da4d641	313
ab50b8ed HD	314	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	315	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
63bfd738	316	perf_event_mmap(vma);
1da177e4 LT	317	return 0;
	318
	319	fail:
	320	vm_unacct_memory(charged);
	321	return error;
	322	}
	323
6a6160a7 HC	324	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	325	unsigned long, prot)
1da177e4 LT	326	{
	327	unsigned long vm_flags, nstart, end, tmp, reqprot;
	328	struct vm_area_struct vma, prev;
	329	int error = -EINVAL;
	330	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	331	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	332	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	333	return -EINVAL;
	334
	335	if (start & ~PAGE_MASK)
	336	return -EINVAL;
	337	if (!len)
	338	return 0;
	339	len = PAGE_ALIGN(len);
	340	end = start + len;
	341	if (end <= start)
	342	return -ENOMEM;
b845f313	343	if (!arch_validate_prot(prot))
1da177e4 LT	344	return -EINVAL;
	345
	346	reqprot = prot;
	347	/*
	348	* Does the application expect PROT_READ to imply PROT_EXEC:
	349	*/
b344e05c	350	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	351	prot \|= PROT_EXEC;
	352
	353	vm_flags = calc_vm_prot_bits(prot);
	354
	355	down_write(&current->mm->mmap_sem);
	356
097d5910	357	vma = find_vma(current->mm, start);
1da177e4 LT	358	error = -ENOMEM;
	359	if (!vma)
	360	goto out;
097d5910	361	prev = vma->vm_prev;
1da177e4 LT	362	if (unlikely(grows & PROT_GROWSDOWN)) {
	363	if (vma->vm_start >= end)
	364	goto out;
	365	start = vma->vm_start;
	366	error = -EINVAL;
	367	if (!(vma->vm_flags & VM_GROWSDOWN))
	368	goto out;
7d12efae	369	} else {
1da177e4 LT	370	if (vma->vm_start > start)
	371	goto out;
	372	if (unlikely(grows & PROT_GROWSUP)) {
	373	end = vma->vm_end;
	374	error = -EINVAL;
	375	if (!(vma->vm_flags & VM_GROWSUP))
	376	goto out;
	377	}
	378	}
	379	if (start > vma->vm_start)
	380	prev = vma;
	381
	382	for (nstart = start ; ; ) {
	383	unsigned long newflags;
	384
7d12efae	385	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
1da177e4	386
7d12efae AM	387	newflags = vm_flags;
7d12efae AM	388	newflags \|= (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4	389
7e2cff42 PBG	390	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	391	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	392	error = -EACCES;
	393	goto out;
	394	}
	395
	396	error = security_file_mprotect(vma, reqprot, prot);
	397	if (error)
	398	goto out;
	399
	400	tmp = vma->vm_end;
	401	if (tmp > end)
	402	tmp = end;
	403	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	404	if (error)
	405	goto out;
	406	nstart = tmp;
	407
	408	if (nstart < prev->vm_end)
	409	nstart = prev->vm_end;
	410	if (nstart >= end)
	411	goto out;
	412
	413	vma = prev->vm_next;
	414	if (!vma \|\| vma->vm_start != nstart) {
	415	error = -ENOMEM;
	416	goto out;
	417	}
	418	}
	419	out:
	420	up_write(&current->mm->mmap_sem);
	421	return error;
	422	}