[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 <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)) {
				/*
				 * A protection check is difficult so
				 * just be safe and disable write
				 */
				make_migration_entry_read(&entry);
				set_pte_at(mm, addr, pte,
					swp_entry_to_pte(entry));
			}
			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 | (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)) {
	97	/*
	98	* A protection check is difficult so
	99	* just be safe and disable write
	100	*/
	101	make_migration_entry_read(&entry);
	102	set_pte_at(mm, addr, pte,
	103	swp_entry_to_pte(entry));
	104	}
7da4d641	105	pages++;
1da177e4 LT	106	}
1da177e4 LT	107	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	108	arch_leave_lazy_mmu_mode();
705e87c0	109	pte_unmap_unlock(pte - 1, ptl);
7da4d641	110
9532fec1	111	*ret_all_same_node = all_same_node;
7da4d641	112	return pages;
1da177e4 LT	113	}
1da177e4 LT	114
4b10e7d5 MG	115	#ifdef CONFIG_NUMA_BALANCING
	116	static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
	117	pmd_t *pmd)
	118	{
	119	spin_lock(&mm->page_table_lock);
	120	set_pmd_at(mm, addr & PMD_MASK, pmd, pmd_mknuma(*pmd));
	121	spin_unlock(&mm->page_table_lock);
	122	}
	123	#else
	124	static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
	125	pmd_t *pmd)
	126	{
	127	BUG();
1da177e4	128	}
4b10e7d5	129	#endif /* CONFIG_NUMA_BALANCING */
1da177e4	130
7da4d641	131	static inline unsigned long change_pmd_range(struct vm_area_struct vma, pud_t pud,
c1e6098b	132	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	133	int dirty_accountable, int prot_numa)
1da177e4 LT	134	{
	135	pmd_t *pmd;
	136	unsigned long next;
7da4d641	137	unsigned long pages = 0;
9532fec1	138	bool all_same_node;
1da177e4 LT	139
	140	pmd = pmd_offset(pud, addr);
	141	do {
	142	next = pmd_addr_end(addr, end);
cd7548ab JW	143	if (pmd_trans_huge(*pmd)) {
cd7548ab JW	144	if (next - addr != HPAGE_PMD_SIZE)
e180377f	145	split_huge_page_pmd(vma, addr, pmd);
4b10e7d5	146	else if (change_huge_pmd(vma, pmd, addr, newprot, prot_numa)) {
7da4d641	147	pages += HPAGE_PMD_NR;
cd7548ab	148	continue;
7da4d641	149	}
cd7548ab JW	150	/* fall through */
cd7548ab JW	151	}
1da177e4 LT	152	if (pmd_none_or_clear_bad(pmd))
1da177e4 LT	153	continue;
4b10e7d5	154	pages += change_pte_range(vma, pmd, addr, next, newprot,
9532fec1	155	dirty_accountable, prot_numa, &all_same_node);
4b10e7d5	156
9532fec1 MG	157	/*
	158	* If we are changing protections for NUMA hinting faults then
	159	* set pmd_numa if the examined pages were all on the same
	160	* node. This allows a regular PMD to be handled as one fault
	161	* and effectively batches the taking of the PTL
	162	*/
	163	if (prot_numa && all_same_node)
4b10e7d5	164	change_pmd_protnuma(vma->vm_mm, addr, pmd);
1da177e4	165	} while (pmd++, addr = next, addr != end);
7da4d641 PZ	166
7da4d641 PZ	167	return pages;
1da177e4 LT	168	}
1da177e4 LT	169
7da4d641	170	static inline unsigned long change_pud_range(struct vm_area_struct vma, pgd_t pgd,
c1e6098b	171	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	172	int dirty_accountable, int prot_numa)
1da177e4 LT	173	{
	174	pud_t *pud;
	175	unsigned long next;
7da4d641	176	unsigned long pages = 0;
1da177e4 LT	177
	178	pud = pud_offset(pgd, addr);
	179	do {
	180	next = pud_addr_end(addr, end);
	181	if (pud_none_or_clear_bad(pud))
	182	continue;
7da4d641	183	pages += change_pmd_range(vma, pud, addr, next, newprot,
4b10e7d5	184	dirty_accountable, prot_numa);
1da177e4	185	} while (pud++, addr = next, addr != end);
7da4d641 PZ	186
7da4d641 PZ	187	return pages;
1da177e4 LT	188	}
1da177e4 LT	189
7da4d641	190	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b	191	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	192	int dirty_accountable, int prot_numa)
1da177e4 LT	193	{
	194	struct mm_struct *mm = vma->vm_mm;
	195	pgd_t *pgd;
	196	unsigned long next;
	197	unsigned long start = addr;
7da4d641	198	unsigned long pages = 0;
1da177e4 LT	199
	200	BUG_ON(addr >= end);
	201	pgd = pgd_offset(mm, addr);
	202	flush_cache_range(vma, addr, end);
1da177e4 LT	203	do {
	204	next = pgd_addr_end(addr, end);
	205	if (pgd_none_or_clear_bad(pgd))
	206	continue;
7da4d641	207	pages += change_pud_range(vma, pgd, addr, next, newprot,
4b10e7d5	208	dirty_accountable, prot_numa);
1da177e4	209	} while (pgd++, addr = next, addr != end);
7da4d641	210
1233d588 IM	211	/* Only flush the TLB if we actually modified any entries: */
	212	if (pages)
	213	flush_tlb_range(vma, start, end);
7da4d641 PZ	214
	215	return pages;
	216	}
	217
	218	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	219	unsigned long end, pgprot_t newprot,
4b10e7d5	220	int dirty_accountable, int prot_numa)
7da4d641 PZ	221	{
	222	struct mm_struct *mm = vma->vm_mm;
	223	unsigned long pages;
	224
	225	mmu_notifier_invalidate_range_start(mm, start, end);
	226	if (is_vm_hugetlb_page(vma))
	227	pages = hugetlb_change_protection(vma, start, end, newprot);
	228	else
4b10e7d5	229	pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
7da4d641 PZ	230	mmu_notifier_invalidate_range_end(mm, start, end);
	231
	232	return pages;
1da177e4 LT	233	}
1da177e4 LT	234
b6a2fea3	235	int
1da177e4 LT	236	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	237	unsigned long start, unsigned long end, unsigned long newflags)
	238	{
	239	struct mm_struct *mm = vma->vm_mm;
	240	unsigned long oldflags = vma->vm_flags;
	241	long nrpages = (end - start) >> PAGE_SHIFT;
	242	unsigned long charged = 0;
1da177e4 LT	243	pgoff_t pgoff;
1da177e4 LT	244	int error;
c1e6098b	245	int dirty_accountable = 0;
1da177e4 LT	246
	247	if (newflags == oldflags) {
	248	*pprev = vma;
	249	return 0;
	250	}
	251
	252	/*
	253	* If we make a private mapping writable we increase our commit;
	254	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	255	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	256	* even if read-only so there is no need to account for them here
1da177e4 LT	257	*/
1da177e4 LT	258	if (newflags & VM_WRITE) {
5a6fe125	259	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	260	VM_SHARED\|VM_NORESERVE))) {
1da177e4	261	charged = nrpages;
191c5424	262	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	263	return -ENOMEM;
	264	newflags \|= VM_ACCOUNT;
	265	}
	266	}
	267
1da177e4 LT	268	/*
	269	* First try to merge with previous and/or next vma.
	270	*/
	271	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	272	pprev = vma_merge(mm, pprev, start, end, newflags,
	273	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	274	if (*pprev) {
	275	vma = *pprev;
	276	goto success;
	277	}
	278
	279	*pprev = vma;
	280
	281	if (start != vma->vm_start) {
	282	error = split_vma(mm, vma, start, 1);
	283	if (error)
	284	goto fail;
	285	}
	286
	287	if (end != vma->vm_end) {
	288	error = split_vma(mm, vma, end, 0);
	289	if (error)
	290	goto fail;
	291	}
	292
	293	success:
	294	/*
	295	* vm_flags and vm_page_prot are protected by the mmap_sem
	296	* held in write mode.
	297	*/
	298	vma->vm_flags = newflags;
1c12c4cf VP	299	vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
	300	vm_get_page_prot(newflags));
	301
c1e6098b	302	if (vma_wants_writenotify(vma)) {
1ddd439e	303	vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
c1e6098b PZ	304	dirty_accountable = 1;
c1e6098b PZ	305	}
d08b3851	306
4b10e7d5	307	change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable, 0);
7da4d641	308
ab50b8ed HD	309	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	310	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
63bfd738	311	perf_event_mmap(vma);
1da177e4 LT	312	return 0;
	313
	314	fail:
	315	vm_unacct_memory(charged);
	316	return error;
	317	}
	318
6a6160a7 HC	319	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	320	unsigned long, prot)
1da177e4 LT	321	{
	322	unsigned long vm_flags, nstart, end, tmp, reqprot;
	323	struct vm_area_struct vma, prev;
	324	int error = -EINVAL;
	325	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	326	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	327	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	328	return -EINVAL;
	329
	330	if (start & ~PAGE_MASK)
	331	return -EINVAL;
	332	if (!len)
	333	return 0;
	334	len = PAGE_ALIGN(len);
	335	end = start + len;
	336	if (end <= start)
	337	return -ENOMEM;
b845f313	338	if (!arch_validate_prot(prot))
1da177e4 LT	339	return -EINVAL;
	340
	341	reqprot = prot;
	342	/*
	343	* Does the application expect PROT_READ to imply PROT_EXEC:
	344	*/
b344e05c	345	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	346	prot \|= PROT_EXEC;
	347
	348	vm_flags = calc_vm_prot_bits(prot);
	349
	350	down_write(&current->mm->mmap_sem);
	351
097d5910	352	vma = find_vma(current->mm, start);
1da177e4 LT	353	error = -ENOMEM;
	354	if (!vma)
	355	goto out;
097d5910	356	prev = vma->vm_prev;
1da177e4 LT	357	if (unlikely(grows & PROT_GROWSDOWN)) {
	358	if (vma->vm_start >= end)
	359	goto out;
	360	start = vma->vm_start;
	361	error = -EINVAL;
	362	if (!(vma->vm_flags & VM_GROWSDOWN))
	363	goto out;
	364	}
	365	else {
	366	if (vma->vm_start > start)
	367	goto out;
	368	if (unlikely(grows & PROT_GROWSUP)) {
	369	end = vma->vm_end;
	370	error = -EINVAL;
	371	if (!(vma->vm_flags & VM_GROWSUP))
	372	goto out;
	373	}
	374	}
	375	if (start > vma->vm_start)
	376	prev = vma;
	377
	378	for (nstart = start ; ; ) {
	379	unsigned long newflags;
	380
	381	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
	382
1da177e4 LT	383	newflags = vm_flags \| (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4 LT	384
7e2cff42 PBG	385	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	386	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	387	error = -EACCES;
	388	goto out;
	389	}
	390
	391	error = security_file_mprotect(vma, reqprot, prot);
	392	if (error)
	393	goto out;
	394
	395	tmp = vma->vm_end;
	396	if (tmp > end)
	397	tmp = end;
	398	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	399	if (error)
	400	goto out;
	401	nstart = tmp;
	402
	403	if (nstart < prev->vm_end)
	404	nstart = prev->vm_end;
	405	if (nstart >= end)
	406	goto out;
	407
	408	vma = prev->vm_next;
	409	if (!vma \|\| vma->vm_start != nstart) {
	410	error = -ENOMEM;
	411	goto out;
	412	}
	413	}
	414	out:
	415	up_write(&current->mm->mmap_sem);
	416	return error;
	417	}