[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_nidpid)
{
	struct mm_struct *mm = vma->vm_mm;
	pte_t *pte, oldpte;
	spinlock_t *ptl;
	unsigned long pages = 0;
	bool all_same_nidpid = true;
	int last_nid = -1;
	int last_pid = -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 nidpid = page_nidpid_last(page);
					int this_nid = nidpid_to_nid(nidpid);
					int this_pid = nidpid_to_pid(nidpid);

					if (last_nid == -1)
						last_nid = this_nid;
					if (last_pid == -1)
						last_pid = this_pid;
					if (last_nid != this_nid ||
					    last_pid != this_pid) {
						all_same_nidpid = false;
					}

					if (!pte_numa(oldpte)) {
						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_nidpid = all_same_nidpid;
	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_nidpid;

	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 {
				int nr_ptes = change_huge_pmd(vma, pmd, addr,
						newprot, prot_numa);

				if (nr_ptes) {
					if (nr_ptes == HPAGE_PMD_NR)
						pages++;

					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_nidpid);

		/*
		 * 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_nidpid)
			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,
b795854b	40	int dirty_accountable, int prot_numa, bool *ret_all_same_nidpid)
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;
b795854b	46	bool all_same_nidpid = true;
9532fec1	47	int last_nid = -1;
b795854b	48	int last_pid = -1;
1da177e4	49
705e87c0	50	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
6606c3e0	51	arch_enter_lazy_mmu_mode();
1da177e4	52	do {
0697212a CL	53	oldpte = *pte;
0697212a CL	54	if (pte_present(oldpte)) {
1da177e4	55	pte_t ptent;
4b10e7d5	56	bool updated = false;
1da177e4	57
1ea0704e	58	ptent = ptep_modify_prot_start(mm, addr, pte);
4b10e7d5 MG	59	if (!prot_numa) {
	60	ptent = pte_modify(ptent, newprot);
	61	updated = true;
	62	} else {
	63	struct page *page;
	64
	65	page = vm_normal_page(vma, addr, oldpte);
	66	if (page) {
b795854b MG	67	int nidpid = page_nidpid_last(page);
	68	int this_nid = nidpid_to_nid(nidpid);
	69	int this_pid = nidpid_to_pid(nidpid);
	70
9532fec1 MG	71	if (last_nid == -1)
9532fec1 MG	72	last_nid = this_nid;
b795854b MG	73	if (last_pid == -1)
	74	last_pid = this_pid;
	75	if (last_nid != this_nid \|\|
	76	last_pid != this_pid) {
	77	all_same_nidpid = false;
	78	}
9532fec1	79
1bc115d8	80	if (!pte_numa(oldpte)) {
4b10e7d5 MG	81	ptent = pte_mknuma(ptent);
	82	updated = true;
	83	}
	84	}
	85	}
1ea0704e	86
c1e6098b PZ	87	/*
	88	* Avoid taking write faults for pages we know to be
	89	* dirty.
	90	*/
4b10e7d5	91	if (dirty_accountable && pte_dirty(ptent)) {
c1e6098b	92	ptent = pte_mkwrite(ptent);
4b10e7d5 MG	93	updated = true;
4b10e7d5 MG	94	}
1ea0704e	95
4b10e7d5 MG	96	if (updated)
4b10e7d5 MG	97	pages++;
1ea0704e	98	ptep_modify_prot_commit(mm, addr, pte, ptent);
ce1744f4	99	} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
0697212a CL	100	swp_entry_t entry = pte_to_swp_entry(oldpte);
	101
	102	if (is_write_migration_entry(entry)) {
	103	/*
	104	* A protection check is difficult so
	105	* just be safe and disable write
	106	*/
	107	make_migration_entry_read(&entry);
	108	set_pte_at(mm, addr, pte,
	109	swp_entry_to_pte(entry));
e920e14c MG	110
e920e14c MG	111	pages++;
0697212a	112	}
1da177e4 LT	113	}
1da177e4 LT	114	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	115	arch_leave_lazy_mmu_mode();
705e87c0	116	pte_unmap_unlock(pte - 1, ptl);
7da4d641	117
b795854b	118	*ret_all_same_nidpid = all_same_nidpid;
7da4d641	119	return pages;
1da177e4 LT	120	}
1da177e4 LT	121
4b10e7d5 MG	122	#ifdef CONFIG_NUMA_BALANCING
4b10e7d5 MG	123	static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
7d12efae	124	pmd_t *pmd)
4b10e7d5 MG	125	{
	126	spin_lock(&mm->page_table_lock);
	127	set_pmd_at(mm, addr & PMD_MASK, pmd, pmd_mknuma(*pmd));
	128	spin_unlock(&mm->page_table_lock);
	129	}
	130	#else
	131	static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
7d12efae	132	pmd_t *pmd)
4b10e7d5 MG	133	{
4b10e7d5 MG	134	BUG();
1da177e4	135	}
4b10e7d5	136	#endif /* CONFIG_NUMA_BALANCING */
1da177e4	137
7d12efae AM	138	static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
	139	pud_t *pud, unsigned long addr, unsigned long end,
	140	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	141	{
	142	pmd_t *pmd;
	143	unsigned long next;
7da4d641	144	unsigned long pages = 0;
b795854b	145	bool all_same_nidpid;
1da177e4 LT	146
	147	pmd = pmd_offset(pud, addr);
	148	do {
	149	next = pmd_addr_end(addr, end);
cd7548ab JW	150	if (pmd_trans_huge(*pmd)) {
cd7548ab JW	151	if (next - addr != HPAGE_PMD_SIZE)
e180377f	152	split_huge_page_pmd(vma, addr, pmd);
f123d74a MG	153	else {
	154	int nr_ptes = change_huge_pmd(vma, pmd, addr,
	155	newprot, prot_numa);
	156
	157	if (nr_ptes) {
	158	if (nr_ptes == HPAGE_PMD_NR)
	159	pages++;
	160
	161	continue;
	162	}
7da4d641	163	}
cd7548ab JW	164	/* fall through */
cd7548ab JW	165	}
1da177e4 LT	166	if (pmd_none_or_clear_bad(pmd))
1da177e4 LT	167	continue;
4b10e7d5	168	pages += change_pte_range(vma, pmd, addr, next, newprot,
b795854b	169	dirty_accountable, prot_numa, &all_same_nidpid);
4b10e7d5	170
9532fec1 MG	171	/*
	172	* If we are changing protections for NUMA hinting faults then
	173	* set pmd_numa if the examined pages were all on the same
	174	* node. This allows a regular PMD to be handled as one fault
	175	* and effectively batches the taking of the PTL
	176	*/
b795854b	177	if (prot_numa && all_same_nidpid)
4b10e7d5	178	change_pmd_protnuma(vma->vm_mm, addr, pmd);
1da177e4	179	} while (pmd++, addr = next, addr != end);
7da4d641 PZ	180
7da4d641 PZ	181	return pages;
1da177e4 LT	182	}
1da177e4 LT	183
7d12efae AM	184	static inline unsigned long change_pud_range(struct vm_area_struct *vma,
	185	pgd_t *pgd, unsigned long addr, unsigned long end,
	186	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	187	{
	188	pud_t *pud;
	189	unsigned long next;
7da4d641	190	unsigned long pages = 0;
1da177e4 LT	191
	192	pud = pud_offset(pgd, addr);
	193	do {
	194	next = pud_addr_end(addr, end);
	195	if (pud_none_or_clear_bad(pud))
	196	continue;
7da4d641	197	pages += change_pmd_range(vma, pud, addr, next, newprot,
4b10e7d5	198	dirty_accountable, prot_numa);
1da177e4	199	} while (pud++, addr = next, addr != end);
7da4d641 PZ	200
7da4d641 PZ	201	return pages;
1da177e4 LT	202	}
1da177e4 LT	203
7da4d641	204	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b	205	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	206	int dirty_accountable, int prot_numa)
1da177e4 LT	207	{
	208	struct mm_struct *mm = vma->vm_mm;
	209	pgd_t *pgd;
	210	unsigned long next;
	211	unsigned long start = addr;
7da4d641	212	unsigned long pages = 0;
1da177e4 LT	213
	214	BUG_ON(addr >= end);
	215	pgd = pgd_offset(mm, addr);
	216	flush_cache_range(vma, addr, end);
1da177e4 LT	217	do {
	218	next = pgd_addr_end(addr, end);
	219	if (pgd_none_or_clear_bad(pgd))
	220	continue;
7da4d641	221	pages += change_pud_range(vma, pgd, addr, next, newprot,
4b10e7d5	222	dirty_accountable, prot_numa);
1da177e4	223	} while (pgd++, addr = next, addr != end);
7da4d641	224
1233d588 IM	225	/* Only flush the TLB if we actually modified any entries: */
	226	if (pages)
	227	flush_tlb_range(vma, start, end);
7da4d641 PZ	228
	229	return pages;
	230	}
	231
	232	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	233	unsigned long end, pgprot_t newprot,
4b10e7d5	234	int dirty_accountable, int prot_numa)
7da4d641 PZ	235	{
	236	struct mm_struct *mm = vma->vm_mm;
	237	unsigned long pages;
	238
	239	mmu_notifier_invalidate_range_start(mm, start, end);
	240	if (is_vm_hugetlb_page(vma))
	241	pages = hugetlb_change_protection(vma, start, end, newprot);
	242	else
4b10e7d5	243	pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
7da4d641 PZ	244	mmu_notifier_invalidate_range_end(mm, start, end);
	245
	246	return pages;
1da177e4 LT	247	}
1da177e4 LT	248
b6a2fea3	249	int
1da177e4 LT	250	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	251	unsigned long start, unsigned long end, unsigned long newflags)
	252	{
	253	struct mm_struct *mm = vma->vm_mm;
	254	unsigned long oldflags = vma->vm_flags;
	255	long nrpages = (end - start) >> PAGE_SHIFT;
	256	unsigned long charged = 0;
1da177e4 LT	257	pgoff_t pgoff;
1da177e4 LT	258	int error;
c1e6098b	259	int dirty_accountable = 0;
1da177e4 LT	260
	261	if (newflags == oldflags) {
	262	*pprev = vma;
	263	return 0;
	264	}
	265
	266	/*
	267	* If we make a private mapping writable we increase our commit;
	268	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	269	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	270	* even if read-only so there is no need to account for them here
1da177e4 LT	271	*/
1da177e4 LT	272	if (newflags & VM_WRITE) {
5a6fe125	273	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	274	VM_SHARED\|VM_NORESERVE))) {
1da177e4	275	charged = nrpages;
191c5424	276	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	277	return -ENOMEM;
	278	newflags \|= VM_ACCOUNT;
	279	}
	280	}
	281
1da177e4 LT	282	/*
	283	* First try to merge with previous and/or next vma.
	284	*/
	285	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	286	pprev = vma_merge(mm, pprev, start, end, newflags,
	287	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	288	if (*pprev) {
	289	vma = *pprev;
	290	goto success;
	291	}
	292
	293	*pprev = vma;
	294
	295	if (start != vma->vm_start) {
	296	error = split_vma(mm, vma, start, 1);
	297	if (error)
	298	goto fail;
	299	}
	300
	301	if (end != vma->vm_end) {
	302	error = split_vma(mm, vma, end, 0);
	303	if (error)
	304	goto fail;
	305	}
	306
	307	success:
	308	/*
	309	* vm_flags and vm_page_prot are protected by the mmap_sem
	310	* held in write mode.
	311	*/
	312	vma->vm_flags = newflags;
1c12c4cf VP	313	vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
	314	vm_get_page_prot(newflags));
	315
c1e6098b	316	if (vma_wants_writenotify(vma)) {
1ddd439e	317	vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
c1e6098b PZ	318	dirty_accountable = 1;
c1e6098b PZ	319	}
d08b3851	320
7d12efae AM	321	change_protection(vma, start, end, vma->vm_page_prot,
7d12efae AM	322	dirty_accountable, 0);
7da4d641	323
ab50b8ed HD	324	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	325	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
63bfd738	326	perf_event_mmap(vma);
1da177e4 LT	327	return 0;
	328
	329	fail:
	330	vm_unacct_memory(charged);
	331	return error;
	332	}
	333
6a6160a7 HC	334	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	335	unsigned long, prot)
1da177e4 LT	336	{
	337	unsigned long vm_flags, nstart, end, tmp, reqprot;
	338	struct vm_area_struct vma, prev;
	339	int error = -EINVAL;
	340	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	341	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	342	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	343	return -EINVAL;
	344
	345	if (start & ~PAGE_MASK)
	346	return -EINVAL;
	347	if (!len)
	348	return 0;
	349	len = PAGE_ALIGN(len);
	350	end = start + len;
	351	if (end <= start)
	352	return -ENOMEM;
b845f313	353	if (!arch_validate_prot(prot))
1da177e4 LT	354	return -EINVAL;
	355
	356	reqprot = prot;
	357	/*
	358	* Does the application expect PROT_READ to imply PROT_EXEC:
	359	*/
b344e05c	360	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	361	prot \|= PROT_EXEC;
	362
	363	vm_flags = calc_vm_prot_bits(prot);
	364
	365	down_write(&current->mm->mmap_sem);
	366
097d5910	367	vma = find_vma(current->mm, start);
1da177e4 LT	368	error = -ENOMEM;
	369	if (!vma)
	370	goto out;
097d5910	371	prev = vma->vm_prev;
1da177e4 LT	372	if (unlikely(grows & PROT_GROWSDOWN)) {
	373	if (vma->vm_start >= end)
	374	goto out;
	375	start = vma->vm_start;
	376	error = -EINVAL;
	377	if (!(vma->vm_flags & VM_GROWSDOWN))
	378	goto out;
7d12efae	379	} else {
1da177e4 LT	380	if (vma->vm_start > start)
	381	goto out;
	382	if (unlikely(grows & PROT_GROWSUP)) {
	383	end = vma->vm_end;
	384	error = -EINVAL;
	385	if (!(vma->vm_flags & VM_GROWSUP))
	386	goto out;
	387	}
	388	}
	389	if (start > vma->vm_start)
	390	prev = vma;
	391
	392	for (nstart = start ; ; ) {
	393	unsigned long newflags;
	394
7d12efae	395	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
1da177e4	396
7d12efae AM	397	newflags = vm_flags;
7d12efae AM	398	newflags \|= (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4	399
7e2cff42 PBG	400	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	401	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	402	error = -EACCES;
	403	goto out;
	404	}
	405
	406	error = security_file_mprotect(vma, reqprot, prot);
	407	if (error)
	408	goto out;
	409
	410	tmp = vma->vm_end;
	411	if (tmp > end)
	412	tmp = end;
	413	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	414	if (error)
	415	goto out;
	416	nstart = tmp;
	417
	418	if (nstart < prev->vm_end)
	419	nstart = prev->vm_end;
	420	if (nstart >= end)
	421	goto out;
	422
	423	vma = prev->vm_next;
	424	if (!vma \|\| vma->vm_start != nstart) {
	425	error = -ENOMEM;
	426	goto out;
	427	}
	428	}
	429	out:
	430	up_write(&current->mm->mmap_sem);
	431	return error;
	432	}