[mirror_ubuntu-artful-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>

#include "internal.h"

/*
 * For a prot_numa update we only hold mmap_sem for read so there is a
 * potential race with faulting where a pmd was temporarily none. This
 * function checks for a transhuge pmd under the appropriate lock. It
 * returns a pte if it was successfully locked or NULL if it raced with
 * a transhuge insertion.
 */
static pte_t *lock_pte_protection(struct vm_area_struct *vma, pmd_t *pmd,
			unsigned long addr, int prot_numa, spinlock_t **ptl)
{
	pte_t *pte;
	spinlock_t *pmdl;

	/* !prot_numa is protected by mmap_sem held for write */
	if (!prot_numa)
		return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);

	pmdl = pmd_lock(vma->vm_mm, pmd);
	if (unlikely(pmd_trans_huge(*pmd) || pmd_none(*pmd))) {
		spin_unlock(pmdl);
		return NULL;
	}

	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
	spin_unlock(pmdl);
	return pte;
}

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 = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
	if (!pte)
		return 0;

	arch_enter_lazy_mmu_mode();
	do {
		oldpte = *pte;
		if (pte_present(oldpte)) {
			pte_t ptent;
			bool preserve_write = prot_numa && pte_write(oldpte);

			/*
			 * Avoid trapping faults against the zero or KSM
			 * pages. See similar comment in change_huge_pmd.
			 */
			if (prot_numa) {
				struct page *page;

				page = vm_normal_page(vma, addr, oldpte);
				if (!page || PageKsm(page))
					continue;

				/* Avoid TLB flush if possible */
				if (pte_protnone(oldpte))
					continue;
			}

			ptent = ptep_modify_prot_start(mm, addr, pte);
			ptent = pte_modify(ptent, newprot);
			if (preserve_write)
				ptent = pte_mkwrite(ptent);

			/* Avoid taking write faults for known dirty pages */
			if (dirty_accountable && pte_dirty(ptent) &&
					(pte_soft_dirty(ptent) ||
					 !(vma->vm_flags & VM_SOFTDIRTY))) {
				ptent = pte_mkwrite(ptent);
			}
			ptep_modify_prot_commit(mm, addr, pte, ptent);
			pages++;
		} else if (IS_ENABLED(CONFIG_MIGRATION)) {
			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;
	struct mm_struct *mm = vma->vm_mm;
	unsigned long next;
	unsigned long pages = 0;
	unsigned long nr_huge_updates = 0;
	unsigned long mni_start = 0;

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

		next = pmd_addr_end(addr, end);
		if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd))
			continue;

		/* invoke the mmu notifier if the pmd is populated */
		if (!mni_start) {
			mni_start = addr;
			mmu_notifier_invalidate_range_start(mm, mni_start, 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++;
					}

					/* huge pmd was handled */
					continue;
				}
			}
			/* fall through, the trans huge pmd just split */
		}
		this_pages = change_pte_range(vma, pmd, addr, next, newprot,
				 dirty_accountable, prot_numa);
		pages += this_pages;
	} while (pmd++, addr = next, addr != end);

	if (mni_start)
		mmu_notifier_invalidate_range_end(mm, mni_start, 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)
{
	unsigned long pages;

	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);

	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;
	dirty_accountable = vma_wants_writenotify(vma);
	vma_set_page_prot(vma);

	change_protection(vma, start, end, vma->vm_page_prot,
			  dirty_accountable, 0);

	/*
	 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
	 * fault on access.
	 */
	if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
			(newflags & VM_WRITE)) {
		populate_vma_page_range(vma, start, end, NULL);
	}

	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
36f88188 KS	32	#include "internal.h"
36f88188 KS	33
1ad9f620 MG	34	/*
	35	* For a prot_numa update we only hold mmap_sem for read so there is a
	36	* potential race with faulting where a pmd was temporarily none. This
	37	* function checks for a transhuge pmd under the appropriate lock. It
	38	* returns a pte if it was successfully locked or NULL if it raced with
	39	* a transhuge insertion.
	40	*/
	41	static pte_t lock_pte_protection(struct vm_area_struct vma, pmd_t *pmd,
	42	unsigned long addr, int prot_numa, spinlock_t **ptl)
	43	{
	44	pte_t *pte;
	45	spinlock_t *pmdl;
	46
	47	/* !prot_numa is protected by mmap_sem held for write */
	48	if (!prot_numa)
	49	return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
	50
	51	pmdl = pmd_lock(vma->vm_mm, pmd);
	52	if (unlikely(pmd_trans_huge(pmd) \|\| pmd_none(pmd))) {
	53	spin_unlock(pmdl);
	54	return NULL;
	55	}
	56
	57	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
	58	spin_unlock(pmdl);
	59	return pte;
	60	}
	61
4b10e7d5	62	static unsigned long change_pte_range(struct vm_area_struct vma, pmd_t pmd,
c1e6098b	63	unsigned long addr, unsigned long end, pgprot_t newprot,
0f19c179	64	int dirty_accountable, int prot_numa)
1da177e4	65	{
4b10e7d5	66	struct mm_struct *mm = vma->vm_mm;
0697212a	67	pte_t *pte, oldpte;
705e87c0	68	spinlock_t *ptl;
7da4d641	69	unsigned long pages = 0;
1da177e4	70
1ad9f620 MG	71	pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
	72	if (!pte)
	73	return 0;
	74
6606c3e0	75	arch_enter_lazy_mmu_mode();
1da177e4	76	do {
0697212a CL	77	oldpte = *pte;
0697212a CL	78	if (pte_present(oldpte)) {
1da177e4	79	pte_t ptent;
b191f9b1	80	bool preserve_write = prot_numa && pte_write(oldpte);
1da177e4	81
e944fd67 MG	82	/*
	83	* Avoid trapping faults against the zero or KSM
	84	* pages. See similar comment in change_huge_pmd.
	85	*/
	86	if (prot_numa) {
	87	struct page *page;
	88
	89	page = vm_normal_page(vma, addr, oldpte);
	90	if (!page \|\| PageKsm(page))
	91	continue;
10c1045f MG	92
	93	/* Avoid TLB flush if possible */
	94	if (pte_protnone(oldpte))
	95	continue;
e944fd67 MG	96	}
e944fd67 MG	97
8a0516ed MG	98	ptent = ptep_modify_prot_start(mm, addr, pte);
8a0516ed MG	99	ptent = pte_modify(ptent, newprot);
b191f9b1 MG	100	if (preserve_write)
b191f9b1 MG	101	ptent = pte_mkwrite(ptent);
4b10e7d5	102
8a0516ed MG	103	/* Avoid taking write faults for known dirty pages */
	104	if (dirty_accountable && pte_dirty(ptent) &&
	105	(pte_soft_dirty(ptent) \|\|
	106	!(vma->vm_flags & VM_SOFTDIRTY))) {
	107	ptent = pte_mkwrite(ptent);
4b10e7d5	108	}
8a0516ed MG	109	ptep_modify_prot_commit(mm, addr, pte, ptent);
8a0516ed MG	110	pages++;
0661a336	111	} else if (IS_ENABLED(CONFIG_MIGRATION)) {
0697212a CL	112	swp_entry_t entry = pte_to_swp_entry(oldpte);
	113
	114	if (is_write_migration_entry(entry)) {
c3d16e16	115	pte_t newpte;
0697212a CL	116	/*
	117	* A protection check is difficult so
	118	* just be safe and disable write
	119	*/
	120	make_migration_entry_read(&entry);
c3d16e16 CG	121	newpte = swp_entry_to_pte(entry);
	122	if (pte_swp_soft_dirty(oldpte))
	123	newpte = pte_swp_mksoft_dirty(newpte);
	124	set_pte_at(mm, addr, pte, newpte);
e920e14c MG	125
e920e14c MG	126	pages++;
0697212a	127	}
1da177e4 LT	128	}
1da177e4 LT	129	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	130	arch_leave_lazy_mmu_mode();
705e87c0	131	pte_unmap_unlock(pte - 1, ptl);
7da4d641 PZ	132
7da4d641 PZ	133	return pages;
1da177e4 LT	134	}
1da177e4 LT	135
7d12efae AM	136	static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
	137	pud_t *pud, unsigned long addr, unsigned long end,
	138	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	139	{
1da177e4 LT	140	pmd_t *pmd;
a5338093	141	struct mm_struct *mm = vma->vm_mm;
1da177e4	142	unsigned long next;
7da4d641	143	unsigned long pages = 0;
72403b4a	144	unsigned long nr_huge_updates = 0;
a5338093	145	unsigned long mni_start = 0;
1da177e4 LT	146
	147	pmd = pmd_offset(pud, addr);
	148	do {
25cbbef1 MG	149	unsigned long this_pages;
25cbbef1 MG	150
1da177e4	151	next = pmd_addr_end(addr, end);
88a9ab6e RR	152	if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd))
88a9ab6e RR	153	continue;
a5338093 RR	154
	155	/* invoke the mmu notifier if the pmd is populated */
	156	if (!mni_start) {
	157	mni_start = addr;
	158	mmu_notifier_invalidate_range_start(mm, mni_start, end);
	159	}
	160
cd7548ab JW	161	if (pmd_trans_huge(*pmd)) {
cd7548ab JW	162	if (next - addr != HPAGE_PMD_SIZE)
e180377f	163	split_huge_page_pmd(vma, addr, pmd);
f123d74a MG	164	else {
f123d74a MG	165	int nr_ptes = change_huge_pmd(vma, pmd, addr,
e944fd67	166	newprot, prot_numa);
f123d74a MG	167
f123d74a MG	168	if (nr_ptes) {
72403b4a MG	169	if (nr_ptes == HPAGE_PMD_NR) {
	170	pages += HPAGE_PMD_NR;
	171	nr_huge_updates++;
	172	}
1ad9f620 MG	173
1ad9f620 MG	174	/* huge pmd was handled */
f123d74a MG	175	continue;
f123d74a MG	176	}
7da4d641	177	}
88a9ab6e	178	/* fall through, the trans huge pmd just split */
cd7548ab	179	}
25cbbef1	180	this_pages = change_pte_range(vma, pmd, addr, next, newprot,
0f19c179	181	dirty_accountable, prot_numa);
25cbbef1	182	pages += this_pages;
1da177e4	183	} while (pmd++, addr = next, addr != end);
7da4d641	184
a5338093 RR	185	if (mni_start)
	186	mmu_notifier_invalidate_range_end(mm, mni_start, end);
	187
72403b4a MG	188	if (nr_huge_updates)
72403b4a MG	189	count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
7da4d641	190	return pages;
1da177e4 LT	191	}
1da177e4 LT	192
7d12efae AM	193	static inline unsigned long change_pud_range(struct vm_area_struct *vma,
	194	pgd_t *pgd, unsigned long addr, unsigned long end,
	195	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	196	{
	197	pud_t *pud;
	198	unsigned long next;
7da4d641	199	unsigned long pages = 0;
1da177e4 LT	200
	201	pud = pud_offset(pgd, addr);
	202	do {
	203	next = pud_addr_end(addr, end);
	204	if (pud_none_or_clear_bad(pud))
	205	continue;
7da4d641	206	pages += change_pmd_range(vma, pud, addr, next, newprot,
4b10e7d5	207	dirty_accountable, prot_numa);
1da177e4	208	} while (pud++, addr = next, addr != end);
7da4d641 PZ	209
7da4d641 PZ	210	return pages;
1da177e4 LT	211	}
1da177e4 LT	212
7da4d641	213	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b	214	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	215	int dirty_accountable, int prot_numa)
1da177e4 LT	216	{
	217	struct mm_struct *mm = vma->vm_mm;
	218	pgd_t *pgd;
	219	unsigned long next;
	220	unsigned long start = addr;
7da4d641	221	unsigned long pages = 0;
1da177e4 LT	222
	223	BUG_ON(addr >= end);
	224	pgd = pgd_offset(mm, addr);
	225	flush_cache_range(vma, addr, end);
20841405	226	set_tlb_flush_pending(mm);
1da177e4 LT	227	do {
	228	next = pgd_addr_end(addr, end);
	229	if (pgd_none_or_clear_bad(pgd))
	230	continue;
7da4d641	231	pages += change_pud_range(vma, pgd, addr, next, newprot,
4b10e7d5	232	dirty_accountable, prot_numa);
1da177e4	233	} while (pgd++, addr = next, addr != end);
7da4d641	234
1233d588 IM	235	/* Only flush the TLB if we actually modified any entries: */
	236	if (pages)
	237	flush_tlb_range(vma, start, end);
20841405	238	clear_tlb_flush_pending(mm);
7da4d641 PZ	239
	240	return pages;
	241	}
	242
	243	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	244	unsigned long end, pgprot_t newprot,
4b10e7d5	245	int dirty_accountable, int prot_numa)
7da4d641	246	{
7da4d641 PZ	247	unsigned long pages;
7da4d641 PZ	248
7da4d641 PZ	249	if (is_vm_hugetlb_page(vma))
	250	pages = hugetlb_change_protection(vma, start, end, newprot);
	251	else
4b10e7d5	252	pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
7da4d641 PZ	253
7da4d641 PZ	254	return pages;
1da177e4 LT	255	}
1da177e4 LT	256
b6a2fea3	257	int
1da177e4 LT	258	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	259	unsigned long start, unsigned long end, unsigned long newflags)
	260	{
	261	struct mm_struct *mm = vma->vm_mm;
	262	unsigned long oldflags = vma->vm_flags;
	263	long nrpages = (end - start) >> PAGE_SHIFT;
	264	unsigned long charged = 0;
1da177e4 LT	265	pgoff_t pgoff;
1da177e4 LT	266	int error;
c1e6098b	267	int dirty_accountable = 0;
1da177e4 LT	268
	269	if (newflags == oldflags) {
	270	*pprev = vma;
	271	return 0;
	272	}
	273
	274	/*
	275	* If we make a private mapping writable we increase our commit;
	276	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	277	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	278	* even if read-only so there is no need to account for them here
1da177e4 LT	279	*/
1da177e4 LT	280	if (newflags & VM_WRITE) {
5a6fe125	281	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	282	VM_SHARED\|VM_NORESERVE))) {
1da177e4	283	charged = nrpages;
191c5424	284	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	285	return -ENOMEM;
	286	newflags \|= VM_ACCOUNT;
	287	}
	288	}
	289
1da177e4 LT	290	/*
	291	* First try to merge with previous and/or next vma.
	292	*/
	293	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	294	pprev = vma_merge(mm, pprev, start, end, newflags,
	295	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	296	if (*pprev) {
	297	vma = *pprev;
	298	goto success;
	299	}
	300
	301	*pprev = vma;
	302
	303	if (start != vma->vm_start) {
	304	error = split_vma(mm, vma, start, 1);
	305	if (error)
	306	goto fail;
	307	}
	308
	309	if (end != vma->vm_end) {
	310	error = split_vma(mm, vma, end, 0);
	311	if (error)
	312	goto fail;
	313	}
	314
	315	success:
	316	/*
	317	* vm_flags and vm_page_prot are protected by the mmap_sem
	318	* held in write mode.
	319	*/
	320	vma->vm_flags = newflags;
64e45507 PF	321	dirty_accountable = vma_wants_writenotify(vma);
64e45507 PF	322	vma_set_page_prot(vma);
d08b3851	323
7d12efae AM	324	change_protection(vma, start, end, vma->vm_page_prot,
7d12efae AM	325	dirty_accountable, 0);
7da4d641	326
36f88188 KS	327	/*
	328	* Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
	329	* fault on access.
	330	*/
	331	if ((oldflags & (VM_WRITE \| VM_SHARED \| VM_LOCKED)) == VM_LOCKED &&
	332	(newflags & VM_WRITE)) {
	333	populate_vma_page_range(vma, start, end, NULL);
	334	}
	335
ab50b8ed HD	336	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	337	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
63bfd738	338	perf_event_mmap(vma);
1da177e4 LT	339	return 0;
	340
	341	fail:
	342	vm_unacct_memory(charged);
	343	return error;
	344	}
	345
6a6160a7 HC	346	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	347	unsigned long, prot)
1da177e4 LT	348	{
	349	unsigned long vm_flags, nstart, end, tmp, reqprot;
	350	struct vm_area_struct vma, prev;
	351	int error = -EINVAL;
	352	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	353	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	354	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	355	return -EINVAL;
	356
	357	if (start & ~PAGE_MASK)
	358	return -EINVAL;
	359	if (!len)
	360	return 0;
	361	len = PAGE_ALIGN(len);
	362	end = start + len;
	363	if (end <= start)
	364	return -ENOMEM;
b845f313	365	if (!arch_validate_prot(prot))
1da177e4 LT	366	return -EINVAL;
	367
	368	reqprot = prot;
	369	/*
	370	* Does the application expect PROT_READ to imply PROT_EXEC:
	371	*/
b344e05c	372	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	373	prot \|= PROT_EXEC;
	374
	375	vm_flags = calc_vm_prot_bits(prot);
	376
	377	down_write(&current->mm->mmap_sem);
	378
097d5910	379	vma = find_vma(current->mm, start);
1da177e4 LT	380	error = -ENOMEM;
	381	if (!vma)
	382	goto out;
097d5910	383	prev = vma->vm_prev;
1da177e4 LT	384	if (unlikely(grows & PROT_GROWSDOWN)) {
	385	if (vma->vm_start >= end)
	386	goto out;
	387	start = vma->vm_start;
	388	error = -EINVAL;
	389	if (!(vma->vm_flags & VM_GROWSDOWN))
	390	goto out;
7d12efae	391	} else {
1da177e4 LT	392	if (vma->vm_start > start)
	393	goto out;
	394	if (unlikely(grows & PROT_GROWSUP)) {
	395	end = vma->vm_end;
	396	error = -EINVAL;
	397	if (!(vma->vm_flags & VM_GROWSUP))
	398	goto out;
	399	}
	400	}
	401	if (start > vma->vm_start)
	402	prev = vma;
	403
	404	for (nstart = start ; ; ) {
	405	unsigned long newflags;
	406
7d12efae	407	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
1da177e4	408
7d12efae AM	409	newflags = vm_flags;
7d12efae AM	410	newflags \|= (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4	411
7e2cff42 PBG	412	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	413	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	414	error = -EACCES;
	415	goto out;
	416	}
	417
	418	error = security_file_mprotect(vma, reqprot, prot);
	419	if (error)
	420	goto out;
	421
	422	tmp = vma->vm_end;
	423	if (tmp > end)
	424	tmp = end;
	425	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	426	if (error)
	427	goto out;
	428	nstart = tmp;
	429
	430	if (nstart < prev->vm_end)
	431	nstart = prev->vm_end;
	432	if (nstart >= end)
	433	goto out;
	434
	435	vma = prev->vm_next;
	436	if (!vma \|\| vma->vm_start != nstart) {
	437	error = -ENOMEM;
	438	goto out;
	439	}
	440	}
	441	out:
	442	up_write(&current->mm->mmap_sem);
	443	return error;
	444	}