[GitHub/mt8127/android_kernel_alcatel_ttab.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)
{
	struct mm_struct *mm = vma->vm_mm;
	pte_t *pte, oldpte;
	spinlock_t *ptl;
	unsigned long pages = 0;

	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	arch_enter_lazy_mmu_mode();
	do {
		oldpte = *pte;
		if (pte_present(oldpte)) {
			pte_t ptent;
			bool updated = false;

			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) {
					/* 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);

	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;

	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->vm_mm, 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);

		if (prot_numa)
			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
	1	/*
	2	* mm/mprotect.c
	3	*
	4	* (C) Copyright 1994 Linus Torvalds
	5	* (C) Copyright 2002 Christoph Hellwig
	6	*
	7	* Address space accounting code <alan@lxorguk.ukuu.org.uk>
	8	* (C) Copyright 2002 Red Hat Inc, All Rights Reserved
	9	*/
	10
	11	#include <linux/mm.h>
	12	#include <linux/hugetlb.h>
	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>
	21	#include <linux/swap.h>
	22	#include <linux/swapops.h>
	23	#include <linux/mmu_notifier.h>
	24	#include <linux/migrate.h>
	25	#include <linux/perf_event.h>
	26	#include <asm/uaccess.h>
	27	#include <asm/pgtable.h>
	28	#include <asm/cacheflush.h>
	29	#include <asm/tlbflush.h>
	30
	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
	38	static unsigned long change_pte_range(struct vm_area_struct vma, pmd_t pmd,
	39	unsigned long addr, unsigned long end, pgprot_t newprot,
	40	int dirty_accountable, int prot_numa)
	41	{
	42	struct mm_struct *mm = vma->vm_mm;
	43	pte_t *pte, oldpte;
	44	spinlock_t *ptl;
	45	unsigned long pages = 0;
	46
	47	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	48	arch_enter_lazy_mmu_mode();
	49	do {
	50	oldpte = *pte;
	51	if (pte_present(oldpte)) {
	52	pte_t ptent;
	53	bool updated = false;
	54
	55	ptent = ptep_modify_prot_start(mm, addr, pte);
	56	if (!prot_numa) {
	57	ptent = pte_modify(ptent, newprot);
	58	updated = true;
	59	} else {
	60	struct page *page;
	61
	62	page = vm_normal_page(vma, addr, oldpte);
	63	if (page) {
	64	/* only check non-shared pages */
	65	if (!pte_numa(oldpte) &&
	66	page_mapcount(page) == 1) {
	67	ptent = pte_mknuma(ptent);
	68	updated = true;
	69	}
	70	}
	71	}
	72
	73	/*
	74	* Avoid taking write faults for pages we know to be
	75	* dirty.
	76	*/
	77	if (dirty_accountable && pte_dirty(ptent)) {
	78	ptent = pte_mkwrite(ptent);
	79	updated = true;
	80	}
	81
	82	if (updated)
	83	pages++;
	84
	85	ptep_modify_prot_commit(mm, addr, pte, ptent);
	86	} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
	87	swp_entry_t entry = pte_to_swp_entry(oldpte);
	88
	89	if (is_write_migration_entry(entry)) {
	90	/*
	91	* A protection check is difficult so
	92	* just be safe and disable write
	93	*/
	94	make_migration_entry_read(&entry);
	95	set_pte_at(mm, addr, pte,
	96	swp_entry_to_pte(entry));
	97	}
	98	pages++;
	99	}
	100	} while (pte++, addr += PAGE_SIZE, addr != end);
	101	arch_leave_lazy_mmu_mode();
	102	pte_unmap_unlock(pte - 1, ptl);
	103
	104	return pages;
	105	}
	106
	107	#ifdef CONFIG_NUMA_BALANCING
	108	static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
	109	pmd_t *pmd)
	110	{
	111	spin_lock(&mm->page_table_lock);
	112	set_pmd_at(mm, addr & PMD_MASK, pmd, pmd_mknuma(*pmd));
	113	spin_unlock(&mm->page_table_lock);
	114	}
	115	#else
	116	static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
	117	pmd_t *pmd)
	118	{
	119	BUG();
	120	}
	121	#endif /* CONFIG_NUMA_BALANCING */
	122
	123	static inline unsigned long change_pmd_range(struct vm_area_struct vma, pud_t pud,
	124	unsigned long addr, unsigned long end, pgprot_t newprot,
	125	int dirty_accountable, int prot_numa)
	126	{
	127	pmd_t *pmd;
	128	unsigned long next;
	129	unsigned long pages = 0;
	130
	131	pmd = pmd_offset(pud, addr);
	132	do {
	133	next = pmd_addr_end(addr, end);
	134	if (pmd_trans_huge(*pmd)) {
	135	if (next - addr != HPAGE_PMD_SIZE)
	136	split_huge_page_pmd(vma->vm_mm, pmd);
	137	else if (change_huge_pmd(vma, pmd, addr, newprot, prot_numa)) {
	138	pages += HPAGE_PMD_NR;
	139	continue;
	140	}
	141	/* fall through */
	142	}
	143	if (pmd_none_or_clear_bad(pmd))
	144	continue;
	145	pages += change_pte_range(vma, pmd, addr, next, newprot,
	146	dirty_accountable, prot_numa);
	147
	148	if (prot_numa)
	149	change_pmd_protnuma(vma->vm_mm, addr, pmd);
	150	} while (pmd++, addr = next, addr != end);
	151
	152	return pages;
	153	}
	154
	155	static inline unsigned long change_pud_range(struct vm_area_struct vma, pgd_t pgd,
	156	unsigned long addr, unsigned long end, pgprot_t newprot,
	157	int dirty_accountable, int prot_numa)
	158	{
	159	pud_t *pud;
	160	unsigned long next;
	161	unsigned long pages = 0;
	162
	163	pud = pud_offset(pgd, addr);
	164	do {
	165	next = pud_addr_end(addr, end);
	166	if (pud_none_or_clear_bad(pud))
	167	continue;
	168	pages += change_pmd_range(vma, pud, addr, next, newprot,
	169	dirty_accountable, prot_numa);
	170	} while (pud++, addr = next, addr != end);
	171
	172	return pages;
	173	}
	174
	175	static unsigned long change_protection_range(struct vm_area_struct *vma,
	176	unsigned long addr, unsigned long end, pgprot_t newprot,
	177	int dirty_accountable, int prot_numa)
	178	{
	179	struct mm_struct *mm = vma->vm_mm;
	180	pgd_t *pgd;
	181	unsigned long next;
	182	unsigned long start = addr;
	183	unsigned long pages = 0;
	184
	185	BUG_ON(addr >= end);
	186	pgd = pgd_offset(mm, addr);
	187	flush_cache_range(vma, addr, end);
	188	do {
	189	next = pgd_addr_end(addr, end);
	190	if (pgd_none_or_clear_bad(pgd))
	191	continue;
	192	pages += change_pud_range(vma, pgd, addr, next, newprot,
	193	dirty_accountable, prot_numa);
	194	} while (pgd++, addr = next, addr != end);
	195
	196	/* Only flush the TLB if we actually modified any entries: */
	197	if (pages)
	198	flush_tlb_range(vma, start, end);
	199
	200	return pages;
	201	}
	202
	203	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	204	unsigned long end, pgprot_t newprot,
	205	int dirty_accountable, int prot_numa)
	206	{
	207	struct mm_struct *mm = vma->vm_mm;
	208	unsigned long pages;
	209
	210	mmu_notifier_invalidate_range_start(mm, start, end);
	211	if (is_vm_hugetlb_page(vma))
	212	pages = hugetlb_change_protection(vma, start, end, newprot);
	213	else
	214	pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
	215	mmu_notifier_invalidate_range_end(mm, start, end);
	216
	217	return pages;
	218	}
	219
	220	int
	221	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	222	unsigned long start, unsigned long end, unsigned long newflags)
	223	{
	224	struct mm_struct *mm = vma->vm_mm;
	225	unsigned long oldflags = vma->vm_flags;
	226	long nrpages = (end - start) >> PAGE_SHIFT;
	227	unsigned long charged = 0;
	228	pgoff_t pgoff;
	229	int error;
	230	int dirty_accountable = 0;
	231
	232	if (newflags == oldflags) {
	233	*pprev = vma;
	234	return 0;
	235	}
	236
	237	/*
	238	* If we make a private mapping writable we increase our commit;
	239	* but (without finer accounting) cannot reduce our commit if we
	240	* make it unwritable again. hugetlb mapping were accounted for
	241	* even if read-only so there is no need to account for them here
	242	*/
	243	if (newflags & VM_WRITE) {
	244	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
	245	VM_SHARED\|VM_NORESERVE))) {
	246	charged = nrpages;
	247	if (security_vm_enough_memory_mm(mm, charged))
	248	return -ENOMEM;
	249	newflags \|= VM_ACCOUNT;
	250	}
	251	}
	252
	253	/*
	254	* First try to merge with previous and/or next vma.
	255	*/
	256	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	257	pprev = vma_merge(mm, pprev, start, end, newflags,
	258	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	259	if (*pprev) {
	260	vma = *pprev;
	261	goto success;
	262	}
	263
	264	*pprev = vma;
	265
	266	if (start != vma->vm_start) {
	267	error = split_vma(mm, vma, start, 1);
	268	if (error)
	269	goto fail;
	270	}
	271
	272	if (end != vma->vm_end) {
	273	error = split_vma(mm, vma, end, 0);
	274	if (error)
	275	goto fail;
	276	}
	277
	278	success:
	279	/*
	280	* vm_flags and vm_page_prot are protected by the mmap_sem
	281	* held in write mode.
	282	*/
	283	vma->vm_flags = newflags;
	284	vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
	285	vm_get_page_prot(newflags));
	286
	287	if (vma_wants_writenotify(vma)) {
	288	vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
	289	dirty_accountable = 1;
	290	}
	291
	292	change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable, 0);
	293
	294	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
	295	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
	296	perf_event_mmap(vma);
	297	return 0;
	298
	299	fail:
	300	vm_unacct_memory(charged);
	301	return error;
	302	}
	303
	304	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
	305	unsigned long, prot)
	306	{
	307	unsigned long vm_flags, nstart, end, tmp, reqprot;
	308	struct vm_area_struct vma, prev;
	309	int error = -EINVAL;
	310	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	311	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	312	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	313	return -EINVAL;
	314
	315	if (start & ~PAGE_MASK)
	316	return -EINVAL;
	317	if (!len)
	318	return 0;
	319	len = PAGE_ALIGN(len);
	320	end = start + len;
	321	if (end <= start)
	322	return -ENOMEM;
	323	if (!arch_validate_prot(prot))
	324	return -EINVAL;
	325
	326	reqprot = prot;
	327	/*
	328	* Does the application expect PROT_READ to imply PROT_EXEC:
	329	*/
	330	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
	331	prot \|= PROT_EXEC;
	332
	333	vm_flags = calc_vm_prot_bits(prot);
	334
	335	down_write(&current->mm->mmap_sem);
	336
	337	vma = find_vma(current->mm, start);
	338	error = -ENOMEM;
	339	if (!vma)
	340	goto out;
	341	prev = vma->vm_prev;
	342	if (unlikely(grows & PROT_GROWSDOWN)) {
	343	if (vma->vm_start >= end)
	344	goto out;
	345	start = vma->vm_start;
	346	error = -EINVAL;
	347	if (!(vma->vm_flags & VM_GROWSDOWN))
	348	goto out;
	349	}
	350	else {
	351	if (vma->vm_start > start)
	352	goto out;
	353	if (unlikely(grows & PROT_GROWSUP)) {
	354	end = vma->vm_end;
	355	error = -EINVAL;
	356	if (!(vma->vm_flags & VM_GROWSUP))
	357	goto out;
	358	}
	359	}
	360	if (start > vma->vm_start)
	361	prev = vma;
	362
	363	for (nstart = start ; ; ) {
	364	unsigned long newflags;
	365
	366	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
	367
	368	newflags = vm_flags \| (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
	369
	370	/* newflags >> 4 shift VM_MAY% in place of VM_% */
	371	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
	372	error = -EACCES;
	373	goto out;
	374	}
	375
	376	error = security_file_mprotect(vma, reqprot, prot);
	377	if (error)
	378	goto out;
	379
	380	tmp = vma->vm_end;
	381	if (tmp > end)
	382	tmp = end;
	383	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	384	if (error)
	385	goto out;
	386	nstart = tmp;
	387
	388	if (nstart < prev->vm_end)
	389	nstart = prev->vm_end;
	390	if (nstart >= end)
	391	goto out;
	392
	393	vma = prev->vm_next;
	394	if (!vma \|\| vma->vm_start != nstart) {
	395	error = -ENOMEM;
	396	goto out;
	397	}
	398	}
	399	out:
	400	up_write(&current->mm->mmap_sem);
	401	return error;
	402	}