[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 mm_struct *mm, pmd_t *pmd,
		unsigned long addr, unsigned long end, pgprot_t newprot,
		int dirty_accountable)
{
	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;

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

			/*
			 * Avoid taking write faults for pages we know to be
			 * dirty.
			 */
			if (dirty_accountable && pte_dirty(ptent))
				ptent = pte_mkwrite(ptent);

			ptep_modify_prot_commit(mm, addr, pte, ptent);
			pages++;
		} 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;
}

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)
{
	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)) {
				pages += HPAGE_PMD_NR;
				continue;
			}
			/* fall through */
		}
		if (pmd_none_or_clear_bad(pmd))
			continue;
		pages += change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
				 dirty_accountable);
	} 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)
{
	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);
	} 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)
{
	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);
	} 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)
{
	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);
	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);

	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
7da4d641	38	static unsigned long change_pte_range(struct mm_struct mm, pmd_t pmd,
c1e6098b PZ	39	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	40	int dirty_accountable)
1da177e4	41	{
0697212a	42	pte_t *pte, oldpte;
705e87c0	43	spinlock_t *ptl;
7da4d641	44	unsigned long pages = 0;
1da177e4	45
705e87c0	46	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
6606c3e0	47	arch_enter_lazy_mmu_mode();
1da177e4	48	do {
0697212a CL	49	oldpte = *pte;
0697212a CL	50	if (pte_present(oldpte)) {
1da177e4 LT	51	pte_t ptent;
1da177e4 LT	52
1ea0704e	53	ptent = ptep_modify_prot_start(mm, addr, pte);
c1e6098b	54	ptent = pte_modify(ptent, newprot);
1ea0704e	55
c1e6098b PZ	56	/*
	57	* Avoid taking write faults for pages we know to be
	58	* dirty.
	59	*/
	60	if (dirty_accountable && pte_dirty(ptent))
	61	ptent = pte_mkwrite(ptent);
1ea0704e JF	62
1ea0704e JF	63	ptep_modify_prot_commit(mm, addr, pte, ptent);
7da4d641	64	pages++;
ce1744f4	65	} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
0697212a CL	66	swp_entry_t entry = pte_to_swp_entry(oldpte);
	67
	68	if (is_write_migration_entry(entry)) {
	69	/*
	70	* A protection check is difficult so
	71	* just be safe and disable write
	72	*/
	73	make_migration_entry_read(&entry);
	74	set_pte_at(mm, addr, pte,
	75	swp_entry_to_pte(entry));
	76	}
7da4d641	77	pages++;
1da177e4 LT	78	}
1da177e4 LT	79	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	80	arch_leave_lazy_mmu_mode();
705e87c0	81	pte_unmap_unlock(pte - 1, ptl);
7da4d641 PZ	82
7da4d641 PZ	83	return pages;
1da177e4 LT	84	}
1da177e4 LT	85
7da4d641	86	static inline unsigned long change_pmd_range(struct vm_area_struct vma, pud_t pud,
c1e6098b PZ	87	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	88	int dirty_accountable)
1da177e4 LT	89	{
	90	pmd_t *pmd;
	91	unsigned long next;
7da4d641	92	unsigned long pages = 0;
1da177e4 LT	93
	94	pmd = pmd_offset(pud, addr);
	95	do {
	96	next = pmd_addr_end(addr, end);
cd7548ab JW	97	if (pmd_trans_huge(*pmd)) {
	98	if (next - addr != HPAGE_PMD_SIZE)
	99	split_huge_page_pmd(vma->vm_mm, pmd);
7da4d641 PZ	100	else if (change_huge_pmd(vma, pmd, addr, newprot)) {
7da4d641 PZ	101	pages += HPAGE_PMD_NR;
cd7548ab	102	continue;
7da4d641	103	}
cd7548ab JW	104	/* fall through */
cd7548ab JW	105	}
1da177e4 LT	106	if (pmd_none_or_clear_bad(pmd))
1da177e4 LT	107	continue;
7da4d641	108	pages += change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
b36f5b07	109	dirty_accountable);
1da177e4	110	} while (pmd++, addr = next, addr != end);
7da4d641 PZ	111
7da4d641 PZ	112	return pages;
1da177e4 LT	113	}
1da177e4 LT	114
7da4d641	115	static inline unsigned long change_pud_range(struct vm_area_struct vma, pgd_t pgd,
c1e6098b PZ	116	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	117	int dirty_accountable)
1da177e4 LT	118	{
	119	pud_t *pud;
	120	unsigned long next;
7da4d641	121	unsigned long pages = 0;
1da177e4 LT	122
	123	pud = pud_offset(pgd, addr);
	124	do {
	125	next = pud_addr_end(addr, end);
	126	if (pud_none_or_clear_bad(pud))
	127	continue;
7da4d641	128	pages += change_pmd_range(vma, pud, addr, next, newprot,
b36f5b07	129	dirty_accountable);
1da177e4	130	} while (pud++, addr = next, addr != end);
7da4d641 PZ	131
7da4d641 PZ	132	return pages;
1da177e4 LT	133	}
1da177e4 LT	134
7da4d641	135	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b PZ	136	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	137	int dirty_accountable)
1da177e4 LT	138	{
	139	struct mm_struct *mm = vma->vm_mm;
	140	pgd_t *pgd;
	141	unsigned long next;
	142	unsigned long start = addr;
7da4d641	143	unsigned long pages = 0;
1da177e4 LT	144
	145	BUG_ON(addr >= end);
	146	pgd = pgd_offset(mm, addr);
	147	flush_cache_range(vma, addr, end);
1da177e4 LT	148	do {
	149	next = pgd_addr_end(addr, end);
	150	if (pgd_none_or_clear_bad(pgd))
	151	continue;
7da4d641	152	pages += change_pud_range(vma, pgd, addr, next, newprot,
b36f5b07	153	dirty_accountable);
1da177e4	154	} while (pgd++, addr = next, addr != end);
7da4d641	155
1233d588 IM	156	/* Only flush the TLB if we actually modified any entries: */
	157	if (pages)
	158	flush_tlb_range(vma, start, end);
7da4d641 PZ	159
	160	return pages;
	161	}
	162
	163	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	164	unsigned long end, pgprot_t newprot,
	165	int dirty_accountable)
	166	{
	167	struct mm_struct *mm = vma->vm_mm;
	168	unsigned long pages;
	169
	170	mmu_notifier_invalidate_range_start(mm, start, end);
	171	if (is_vm_hugetlb_page(vma))
	172	pages = hugetlb_change_protection(vma, start, end, newprot);
	173	else
	174	pages = change_protection_range(vma, start, end, newprot, dirty_accountable);
	175	mmu_notifier_invalidate_range_end(mm, start, end);
	176
	177	return pages;
1da177e4 LT	178	}
1da177e4 LT	179
b6a2fea3	180	int
1da177e4 LT	181	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	182	unsigned long start, unsigned long end, unsigned long newflags)
	183	{
	184	struct mm_struct *mm = vma->vm_mm;
	185	unsigned long oldflags = vma->vm_flags;
	186	long nrpages = (end - start) >> PAGE_SHIFT;
	187	unsigned long charged = 0;
1da177e4 LT	188	pgoff_t pgoff;
1da177e4 LT	189	int error;
c1e6098b	190	int dirty_accountable = 0;
1da177e4 LT	191
	192	if (newflags == oldflags) {
	193	*pprev = vma;
	194	return 0;
	195	}
	196
	197	/*
	198	* If we make a private mapping writable we increase our commit;
	199	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	200	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	201	* even if read-only so there is no need to account for them here
1da177e4 LT	202	*/
1da177e4 LT	203	if (newflags & VM_WRITE) {
5a6fe125	204	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	205	VM_SHARED\|VM_NORESERVE))) {
1da177e4	206	charged = nrpages;
191c5424	207	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	208	return -ENOMEM;
	209	newflags \|= VM_ACCOUNT;
	210	}
	211	}
	212
1da177e4 LT	213	/*
	214	* First try to merge with previous and/or next vma.
	215	*/
	216	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	217	pprev = vma_merge(mm, pprev, start, end, newflags,
	218	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	219	if (*pprev) {
	220	vma = *pprev;
	221	goto success;
	222	}
	223
	224	*pprev = vma;
	225
	226	if (start != vma->vm_start) {
	227	error = split_vma(mm, vma, start, 1);
	228	if (error)
	229	goto fail;
	230	}
	231
	232	if (end != vma->vm_end) {
	233	error = split_vma(mm, vma, end, 0);
	234	if (error)
	235	goto fail;
	236	}
	237
	238	success:
	239	/*
	240	* vm_flags and vm_page_prot are protected by the mmap_sem
	241	* held in write mode.
	242	*/
	243	vma->vm_flags = newflags;
1c12c4cf VP	244	vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
	245	vm_get_page_prot(newflags));
	246
c1e6098b	247	if (vma_wants_writenotify(vma)) {
1ddd439e	248	vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
c1e6098b PZ	249	dirty_accountable = 1;
c1e6098b PZ	250	}
d08b3851	251
7da4d641 PZ	252	change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
7da4d641 PZ	253
ab50b8ed HD	254	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	255	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
63bfd738	256	perf_event_mmap(vma);
1da177e4 LT	257	return 0;
	258
	259	fail:
	260	vm_unacct_memory(charged);
	261	return error;
	262	}
	263
6a6160a7 HC	264	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	265	unsigned long, prot)
1da177e4 LT	266	{
	267	unsigned long vm_flags, nstart, end, tmp, reqprot;
	268	struct vm_area_struct vma, prev;
	269	int error = -EINVAL;
	270	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	271	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	272	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	273	return -EINVAL;
	274
	275	if (start & ~PAGE_MASK)
	276	return -EINVAL;
	277	if (!len)
	278	return 0;
	279	len = PAGE_ALIGN(len);
	280	end = start + len;
	281	if (end <= start)
	282	return -ENOMEM;
b845f313	283	if (!arch_validate_prot(prot))
1da177e4 LT	284	return -EINVAL;
	285
	286	reqprot = prot;
	287	/*
	288	* Does the application expect PROT_READ to imply PROT_EXEC:
	289	*/
b344e05c	290	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	291	prot \|= PROT_EXEC;
	292
	293	vm_flags = calc_vm_prot_bits(prot);
	294
	295	down_write(&current->mm->mmap_sem);
	296
097d5910	297	vma = find_vma(current->mm, start);
1da177e4 LT	298	error = -ENOMEM;
	299	if (!vma)
	300	goto out;
097d5910	301	prev = vma->vm_prev;
1da177e4 LT	302	if (unlikely(grows & PROT_GROWSDOWN)) {
	303	if (vma->vm_start >= end)
	304	goto out;
	305	start = vma->vm_start;
	306	error = -EINVAL;
	307	if (!(vma->vm_flags & VM_GROWSDOWN))
	308	goto out;
	309	}
	310	else {
	311	if (vma->vm_start > start)
	312	goto out;
	313	if (unlikely(grows & PROT_GROWSUP)) {
	314	end = vma->vm_end;
	315	error = -EINVAL;
	316	if (!(vma->vm_flags & VM_GROWSUP))
	317	goto out;
	318	}
	319	}
	320	if (start > vma->vm_start)
	321	prev = vma;
	322
	323	for (nstart = start ; ; ) {
	324	unsigned long newflags;
	325
	326	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
	327
1da177e4 LT	328	newflags = vm_flags \| (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4 LT	329
7e2cff42 PBG	330	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	331	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	332	error = -EACCES;
	333	goto out;
	334	}
	335
	336	error = security_file_mprotect(vma, reqprot, prot);
	337	if (error)
	338	goto out;
	339
	340	tmp = vma->vm_end;
	341	if (tmp > end)
	342	tmp = end;
	343	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	344	if (error)
	345	goto out;
	346	nstart = tmp;
	347
	348	if (nstart < prev->vm_end)
	349	nstart = prev->vm_end;
	350	if (nstart >= end)
	351	goto out;
	352
	353	vma = prev->vm_next;
	354	if (!vma \|\| vma->vm_start != nstart) {
	355	error = -ENOMEM;
	356	goto out;
	357	}
	358	}
	359	out:
	360	up_write(&current->mm->mmap_sem);
	361	return error;
	362	}