Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 896 insertions, 0 deletions

diff --git a/mm/mprotect.c b/mm/mprotect.c
new file mode 100644
index 0000000000..b94fbb45d5
--- /dev/null
+++ b/mm/mprotect.c
@@ -0,0 +1,896 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  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/pagewalk.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/pkeys.h>
+#include <linux/ksm.h>
+#include <linux/uaccess.h>
+#include <linux/mm_inline.h>
+#include <linux/pgtable.h>
+#include <linux/sched/sysctl.h>
+#include <linux/userfaultfd_k.h>
+#include <linux/memory-tiers.h>
+#include <asm/cacheflush.h>
+#include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
+#include <asm/tlb.h>
+
+#include "internal.h"
+
+bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
+			     pte_t pte)
+{
+	struct page *page;
+
+	if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
+		return false;
+
+	/* Don't touch entries that are not even readable. */
+	if (pte_protnone(pte))
+		return false;
+
+	/* Do we need write faults for softdirty tracking? */
+	if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte))
+		return false;
+
+	/* Do we need write faults for uffd-wp tracking? */
+	if (userfaultfd_pte_wp(vma, pte))
+		return false;
+
+	if (!(vma->vm_flags & VM_SHARED)) {
+		/*
+		 * Writable MAP_PRIVATE mapping: We can only special-case on
+		 * exclusive anonymous pages, because we know that our
+		 * write-fault handler similarly would map them writable without
+		 * any additional checks while holding the PT lock.
+		 */
+		page = vm_normal_page(vma, addr, pte);
+		return page && PageAnon(page) && PageAnonExclusive(page);
+	}
+
+	/*
+	 * Writable MAP_SHARED mapping: "clean" might indicate that the FS still
+	 * needs a real write-fault for writenotify
+	 * (see vma_wants_writenotify()). If "dirty", the assumption is that the
+	 * FS was already notified and we can simply mark the PTE writable
+	 * just like the write-fault handler would do.
+	 */
+	return pte_dirty(pte);
+}
+
+static long change_pte_range(struct mmu_gather *tlb,
+		struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr,
+		unsigned long end, pgprot_t newprot, unsigned long cp_flags)
+{
+	pte_t *pte, oldpte;
+	spinlock_t *ptl;
+	long pages = 0;
+	int target_node = NUMA_NO_NODE;
+	bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
+	bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
+	bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
+
+	tlb_change_page_size(tlb, PAGE_SIZE);
+	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	if (!pte)
+		return -EAGAIN;
+
+	/* Get target node for single threaded private VMAs */
+	if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
+	    atomic_read(&vma->vm_mm->mm_users) == 1)
+		target_node = numa_node_id();
+
+	flush_tlb_batched_pending(vma->vm_mm);
+	arch_enter_lazy_mmu_mode();
+	do {
+		oldpte = ptep_get(pte);
+		if (pte_present(oldpte)) {
+			pte_t ptent;
+
+			/*
+			 * Avoid trapping faults against the zero or KSM
+			 * pages. See similar comment in change_huge_pmd.
+			 */
+			if (prot_numa) {
+				struct page *page;
+				int nid;
+				bool toptier;
+
+				/* Avoid TLB flush if possible */
+				if (pte_protnone(oldpte))
+					continue;
+
+				page = vm_normal_page(vma, addr, oldpte);
+				if (!page || is_zone_device_page(page) || PageKsm(page))
+					continue;
+
+				/* Also skip shared copy-on-write pages */
+				if (is_cow_mapping(vma->vm_flags) &&
+				    page_count(page) != 1)
+					continue;
+
+				/*
+				 * While migration can move some dirty pages,
+				 * it cannot move them all from MIGRATE_ASYNC
+				 * context.
+				 */
+				if (page_is_file_lru(page) && PageDirty(page))
+					continue;
+
+				/*
+				 * Don't mess with PTEs if page is already on the node
+				 * a single-threaded process is running on.
+				 */
+				nid = page_to_nid(page);
+				if (target_node == nid)
+					continue;
+				toptier = node_is_toptier(nid);
+
+				/*
+				 * Skip scanning top tier node if normal numa
+				 * balancing is disabled
+				 */
+				if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
+				    toptier)
+					continue;
+				if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
+				    !toptier)
+					xchg_page_access_time(page,
+						jiffies_to_msecs(jiffies));
+			}
+
+			oldpte = ptep_modify_prot_start(vma, addr, pte);
+			ptent = pte_modify(oldpte, newprot);
+
+			if (uffd_wp)
+				ptent = pte_mkuffd_wp(ptent);
+			else if (uffd_wp_resolve)
+				ptent = pte_clear_uffd_wp(ptent);
+
+			/*
+			 * In some writable, shared mappings, we might want
+			 * to catch actual write access -- see
+			 * vma_wants_writenotify().
+			 *
+			 * In all writable, private mappings, we have to
+			 * properly handle COW.
+			 *
+			 * In both cases, we can sometimes still change PTEs
+			 * writable and avoid the write-fault handler, for
+			 * example, if a PTE is already dirty and no other
+			 * COW or special handling is required.
+			 */
+			if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) &&
+			    !pte_write(ptent) &&
+			    can_change_pte_writable(vma, addr, ptent))
+				ptent = pte_mkwrite(ptent, vma);
+
+			ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
+			if (pte_needs_flush(oldpte, ptent))
+				tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
+			pages++;
+		} else if (is_swap_pte(oldpte)) {
+			swp_entry_t entry = pte_to_swp_entry(oldpte);
+			pte_t newpte;
+
+			if (is_writable_migration_entry(entry)) {
+				struct page *page = pfn_swap_entry_to_page(entry);
+
+				/*
+				 * A protection check is difficult so
+				 * just be safe and disable write
+				 */
+				if (PageAnon(page))
+					entry = make_readable_exclusive_migration_entry(
+							     swp_offset(entry));
+				else
+					entry = make_readable_migration_entry(swp_offset(entry));
+				newpte = swp_entry_to_pte(entry);
+				if (pte_swp_soft_dirty(oldpte))
+					newpte = pte_swp_mksoft_dirty(newpte);
+			} else if (is_writable_device_private_entry(entry)) {
+				/*
+				 * We do not preserve soft-dirtiness. See
+				 * copy_nonpresent_pte() for explanation.
+				 */
+				entry = make_readable_device_private_entry(
+							swp_offset(entry));
+				newpte = swp_entry_to_pte(entry);
+				if (pte_swp_uffd_wp(oldpte))
+					newpte = pte_swp_mkuffd_wp(newpte);
+			} else if (is_writable_device_exclusive_entry(entry)) {
+				entry = make_readable_device_exclusive_entry(
+							swp_offset(entry));
+				newpte = swp_entry_to_pte(entry);
+				if (pte_swp_soft_dirty(oldpte))
+					newpte = pte_swp_mksoft_dirty(newpte);
+				if (pte_swp_uffd_wp(oldpte))
+					newpte = pte_swp_mkuffd_wp(newpte);
+			} else if (is_pte_marker_entry(entry)) {
+				/*
+				 * Ignore error swap entries unconditionally,
+				 * because any access should sigbus anyway.
+				 */
+				if (is_poisoned_swp_entry(entry))
+					continue;
+				/*
+				 * If this is uffd-wp pte marker and we'd like
+				 * to unprotect it, drop it; the next page
+				 * fault will trigger without uffd trapping.
+				 */
+				if (uffd_wp_resolve) {
+					pte_clear(vma->vm_mm, addr, pte);
+					pages++;
+				}
+				continue;
+			} else {
+				newpte = oldpte;
+			}
+
+			if (uffd_wp)
+				newpte = pte_swp_mkuffd_wp(newpte);
+			else if (uffd_wp_resolve)
+				newpte = pte_swp_clear_uffd_wp(newpte);
+
+			if (!pte_same(oldpte, newpte)) {
+				set_pte_at(vma->vm_mm, addr, pte, newpte);
+				pages++;
+			}
+		} else {
+			/* It must be an none page, or what else?.. */
+			WARN_ON_ONCE(!pte_none(oldpte));
+
+			/*
+			 * Nobody plays with any none ptes besides
+			 * userfaultfd when applying the protections.
+			 */
+			if (likely(!uffd_wp))
+				continue;
+
+			if (userfaultfd_wp_use_markers(vma)) {
+				/*
+				 * For file-backed mem, we need to be able to
+				 * wr-protect a none pte, because even if the
+				 * pte is none, the page/swap cache could
+				 * exist.  Doing that by install a marker.
+				 */
+				set_pte_at(vma->vm_mm, addr, pte,
+					   make_pte_marker(PTE_MARKER_UFFD_WP));
+				pages++;
+			}
+		}
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+	arch_leave_lazy_mmu_mode();
+	pte_unmap_unlock(pte - 1, ptl);
+
+	return pages;
+}
+
+/*
+ * Return true if we want to split THPs into PTE mappings in change
+ * protection procedure, false otherwise.
+ */
+static inline bool
+pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags)
+{
+	/*
+	 * pte markers only resides in pte level, if we need pte markers,
+	 * we need to split.  We cannot wr-protect shmem thp because file
+	 * thp is handled differently when split by erasing the pmd so far.
+	 */
+	return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
+}
+
+/*
+ * Return true if we want to populate pgtables in change protection
+ * procedure, false otherwise
+ */
+static inline bool
+pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags)
+{
+	/* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */
+	if (!(cp_flags & MM_CP_UFFD_WP))
+		return false;
+
+	/* Populate if the userfaultfd mode requires pte markers */
+	return userfaultfd_wp_use_markers(vma);
+}
+
+/*
+ * Populate the pgtable underneath for whatever reason if requested.
+ * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable
+ * allocation failures during page faults by kicking OOM and returning
+ * error.
+ */
+#define  change_pmd_prepare(vma, pmd, cp_flags)				\
+	({								\
+		long err = 0;						\
+		if (unlikely(pgtable_populate_needed(vma, cp_flags))) {	\
+			if (pte_alloc(vma->vm_mm, pmd))			\
+				err = -ENOMEM;				\
+		}							\
+		err;							\
+	})
+
+/*
+ * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
+ * have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
+ * while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
+ */
+#define  change_prepare(vma, high, low, addr, cp_flags)			\
+	  ({								\
+		long err = 0;						\
+		if (unlikely(pgtable_populate_needed(vma, cp_flags))) {	\
+			low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
+			if (p == NULL)					\
+				err = -ENOMEM;				\
+		}							\
+		err;							\
+	})
+
+static inline long change_pmd_range(struct mmu_gather *tlb,
+		struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
+		unsigned long end, pgprot_t newprot, unsigned long cp_flags)
+{
+	pmd_t *pmd;
+	unsigned long next;
+	long pages = 0;
+	unsigned long nr_huge_updates = 0;
+	struct mmu_notifier_range range;
+
+	range.start = 0;
+
+	pmd = pmd_offset(pud, addr);
+	do {
+		long ret;
+		pmd_t _pmd;
+again:
+		next = pmd_addr_end(addr, end);
+
+		ret = change_pmd_prepare(vma, pmd, cp_flags);
+		if (ret) {
+			pages = ret;
+			break;
+		}
+
+		if (pmd_none(*pmd))
+			goto next;
+
+		/* invoke the mmu notifier if the pmd is populated */
+		if (!range.start) {
+			mmu_notifier_range_init(&range,
+				MMU_NOTIFY_PROTECTION_VMA, 0,
+				vma->vm_mm, addr, end);
+			mmu_notifier_invalidate_range_start(&range);
+		}
+
+		_pmd = pmdp_get_lockless(pmd);
+		if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) {
+			if ((next - addr != HPAGE_PMD_SIZE) ||
+			    pgtable_split_needed(vma, cp_flags)) {
+				__split_huge_pmd(vma, pmd, addr, false, NULL);
+				/*
+				 * For file-backed, the pmd could have been
+				 * cleared; make sure pmd populated if
+				 * necessary, then fall-through to pte level.
+				 */
+				ret = change_pmd_prepare(vma, pmd, cp_flags);
+				if (ret) {
+					pages = ret;
+					break;
+				}
+			} else {
+				ret = change_huge_pmd(tlb, vma, pmd,
+						addr, newprot, cp_flags);
+				if (ret) {
+					if (ret == HPAGE_PMD_NR) {
+						pages += HPAGE_PMD_NR;
+						nr_huge_updates++;
+					}
+
+					/* huge pmd was handled */
+					goto next;
+				}
+			}
+			/* fall through, the trans huge pmd just split */
+		}
+
+		ret = change_pte_range(tlb, vma, pmd, addr, next, newprot,
+				       cp_flags);
+		if (ret < 0)
+			goto again;
+		pages += ret;
+next:
+		cond_resched();
+	} while (pmd++, addr = next, addr != end);
+
+	if (range.start)
+		mmu_notifier_invalidate_range_end(&range);
+
+	if (nr_huge_updates)
+		count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
+	return pages;
+}
+
+static inline long change_pud_range(struct mmu_gather *tlb,
+		struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
+		unsigned long end, pgprot_t newprot, unsigned long cp_flags)
+{
+	pud_t *pud;
+	unsigned long next;
+	long pages = 0, ret;
+
+	pud = pud_offset(p4d, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		ret = change_prepare(vma, pud, pmd, addr, cp_flags);
+		if (ret)
+			return ret;
+		if (pud_none_or_clear_bad(pud))
+			continue;
+		pages += change_pmd_range(tlb, vma, pud, addr, next, newprot,
+					  cp_flags);
+	} while (pud++, addr = next, addr != end);
+
+	return pages;
+}
+
+static inline long change_p4d_range(struct mmu_gather *tlb,
+		struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
+		unsigned long end, pgprot_t newprot, unsigned long cp_flags)
+{
+	p4d_t *p4d;
+	unsigned long next;
+	long pages = 0, ret;
+
+	p4d = p4d_offset(pgd, addr);
+	do {
+		next = p4d_addr_end(addr, end);
+		ret = change_prepare(vma, p4d, pud, addr, cp_flags);
+		if (ret)
+			return ret;
+		if (p4d_none_or_clear_bad(p4d))
+			continue;
+		pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
+					  cp_flags);
+	} while (p4d++, addr = next, addr != end);
+
+	return pages;
+}
+
+static long change_protection_range(struct mmu_gather *tlb,
+		struct vm_area_struct *vma, unsigned long addr,
+		unsigned long end, pgprot_t newprot, unsigned long cp_flags)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pgd_t *pgd;
+	unsigned long next;
+	long pages = 0, ret;
+
+	BUG_ON(addr >= end);
+	pgd = pgd_offset(mm, addr);
+	tlb_start_vma(tlb, vma);
+	do {
+		next = pgd_addr_end(addr, end);
+		ret = change_prepare(vma, pgd, p4d, addr, cp_flags);
+		if (ret) {
+			pages = ret;
+			break;
+		}
+		if (pgd_none_or_clear_bad(pgd))
+			continue;
+		pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
+					  cp_flags);
+	} while (pgd++, addr = next, addr != end);
+
+	tlb_end_vma(tlb, vma);
+
+	return pages;
+}
+
+long change_protection(struct mmu_gather *tlb,
+		       struct vm_area_struct *vma, unsigned long start,
+		       unsigned long end, unsigned long cp_flags)
+{
+	pgprot_t newprot = vma->vm_page_prot;
+	long pages;
+
+	BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
+
+#ifdef CONFIG_NUMA_BALANCING
+	/*
+	 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking)
+	 * are expected to reflect their requirements via VMA flags such that
+	 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly.
+	 */
+	if (cp_flags & MM_CP_PROT_NUMA)
+		newprot = PAGE_NONE;
+#else
+	WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA);
+#endif
+
+	if (is_vm_hugetlb_page(vma))
+		pages = hugetlb_change_protection(vma, start, end, newprot,
+						  cp_flags);
+	else
+		pages = change_protection_range(tlb, vma, start, end, newprot,
+						cp_flags);
+
+	return pages;
+}
+
+static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
+			       unsigned long next, struct mm_walk *walk)
+{
+	return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
+				  *(pgprot_t *)(walk->private)) ?
+		0 : -EACCES;
+}
+
+static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
+				   unsigned long addr, unsigned long next,
+				   struct mm_walk *walk)
+{
+	return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
+				  *(pgprot_t *)(walk->private)) ?
+		0 : -EACCES;
+}
+
+static int prot_none_test(unsigned long addr, unsigned long next,
+			  struct mm_walk *walk)
+{
+	return 0;
+}
+
+static const struct mm_walk_ops prot_none_walk_ops = {
+	.pte_entry		= prot_none_pte_entry,
+	.hugetlb_entry		= prot_none_hugetlb_entry,
+	.test_walk		= prot_none_test,
+	.walk_lock		= PGWALK_WRLOCK,
+};
+
+int
+mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
+	       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 int mm_cp_flags = 0;
+	unsigned long charged = 0;
+	pgoff_t pgoff;
+	int error;
+
+	if (newflags == oldflags) {
+		*pprev = vma;
+		return 0;
+	}
+
+	/*
+	 * Do PROT_NONE PFN permission checks here when we can still
+	 * bail out without undoing a lot of state. This is a rather
+	 * uncommon case, so doesn't need to be very optimized.
+	 */
+	if (arch_has_pfn_modify_check() &&
+	    (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
+	    (newflags & VM_ACCESS_FLAGS) == 0) {
+		pgprot_t new_pgprot = vm_get_page_prot(newflags);
+
+		error = walk_page_range(current->mm, start, end,
+				&prot_none_walk_ops, &new_pgprot);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * 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) {
+		/* Check space limits when area turns into data. */
+		if (!may_expand_vm(mm, newflags, nrpages) &&
+				may_expand_vm(mm, oldflags, nrpages))
+			return -ENOMEM;
+		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(vmi, mm, *pprev, start, end, newflags,
+			   vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
+			   vma->vm_userfaultfd_ctx, anon_vma_name(vma));
+	if (*pprev) {
+		vma = *pprev;
+		VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
+		goto success;
+	}
+
+	*pprev = vma;
+
+	if (start != vma->vm_start) {
+		error = split_vma(vmi, vma, start, 1);
+		if (error)
+			goto fail;
+	}
+
+	if (end != vma->vm_end) {
+		error = split_vma(vmi, vma, end, 0);
+		if (error)
+			goto fail;
+	}
+
+success:
+	/*
+	 * vm_flags and vm_page_prot are protected by the mmap_lock
+	 * held in write mode.
+	 */
+	vma_start_write(vma);
+	vm_flags_reset(vma, newflags);
+	if (vma_wants_manual_pte_write_upgrade(vma))
+		mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
+	vma_set_page_prot(vma);
+
+	change_protection(tlb, vma, start, end, mm_cp_flags);
+
+	/*
+	 * 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, -nrpages);
+	vm_stat_account(mm, newflags, nrpages);
+	perf_event_mmap(vma);
+	return 0;
+
+fail:
+	vm_unacct_memory(charged);
+	return error;
+}
+
+/*
+ * pkey==-1 when doing a legacy mprotect()
+ */
+static int do_mprotect_pkey(unsigned long start, size_t len,
+		unsigned long prot, int pkey)
+{
+	unsigned long nstart, end, tmp, reqprot;
+	struct vm_area_struct *vma, *prev;
+	int error;
+	const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
+	const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
+				(prot & PROT_READ);
+	struct mmu_gather tlb;
+	struct vma_iterator vmi;
+
+	start = untagged_addr(start);
+
+	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, start))
+		return -EINVAL;
+
+	reqprot = prot;
+
+	if (mmap_write_lock_killable(current->mm))
+		return -EINTR;
+
+	/*
+	 * If userspace did not allocate the pkey, do not let
+	 * them use it here.
+	 */
+	error = -EINVAL;
+	if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
+		goto out;
+
+	vma_iter_init(&vmi, current->mm, start);
+	vma = vma_find(&vmi, end);
+	error = -ENOMEM;
+	if (!vma)
+		goto out;
+
+	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;
+		}
+	}
+
+	prev = vma_prev(&vmi);
+	if (start > vma->vm_start)
+		prev = vma;
+
+	tlb_gather_mmu(&tlb, current->mm);
+	nstart = start;
+	tmp = vma->vm_start;
+	for_each_vma_range(vmi, vma, end) {
+		unsigned long mask_off_old_flags;
+		unsigned long newflags;
+		int new_vma_pkey;
+
+		if (vma->vm_start != tmp) {
+			error = -ENOMEM;
+			break;
+		}
+
+		/* Does the application expect PROT_READ to imply PROT_EXEC */
+		if (rier && (vma->vm_flags & VM_MAYEXEC))
+			prot |= PROT_EXEC;
+
+		/*
+		 * Each mprotect() call explicitly passes r/w/x permissions.
+		 * If a permission is not passed to mprotect(), it must be
+		 * cleared from the VMA.
+		 */
+		mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR;
+
+		new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
+		newflags = calc_vm_prot_bits(prot, new_vma_pkey);
+		newflags |= (vma->vm_flags & ~mask_off_old_flags);
+
+		/* newflags >> 4 shift VM_MAY% in place of VM_% */
+		if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
+			error = -EACCES;
+			break;
+		}
+
+		if (map_deny_write_exec(vma, newflags)) {
+			error = -EACCES;
+			break;
+		}
+
+		/* Allow architectures to sanity-check the new flags */
+		if (!arch_validate_flags(newflags)) {
+			error = -EINVAL;
+			break;
+		}
+
+		error = security_file_mprotect(vma, reqprot, prot);
+		if (error)
+			break;
+
+		tmp = vma->vm_end;
+		if (tmp > end)
+			tmp = end;
+
+		if (vma->vm_ops && vma->vm_ops->mprotect) {
+			error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
+			if (error)
+				break;
+		}
+
+		error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags);
+		if (error)
+			break;
+
+		tmp = vma_iter_end(&vmi);
+		nstart = tmp;
+		prot = reqprot;
+	}
+	tlb_finish_mmu(&tlb);
+
+	if (!error && tmp < end)
+		error = -ENOMEM;
+
+out:
+	mmap_write_unlock(current->mm);
+	return error;
+}
+
+SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
+		unsigned long, prot)
+{
+	return do_mprotect_pkey(start, len, prot, -1);
+}
+
+#ifdef CONFIG_ARCH_HAS_PKEYS
+
+SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
+		unsigned long, prot, int, pkey)
+{
+	return do_mprotect_pkey(start, len, prot, pkey);
+}
+
+SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
+{
+	int pkey;
+	int ret;
+
+	/* No flags supported yet. */
+	if (flags)
+		return -EINVAL;
+	/* check for unsupported init values */
+	if (init_val & ~PKEY_ACCESS_MASK)
+		return -EINVAL;
+
+	mmap_write_lock(current->mm);
+	pkey = mm_pkey_alloc(current->mm);
+
+	ret = -ENOSPC;
+	if (pkey == -1)
+		goto out;
+
+	ret = arch_set_user_pkey_access(current, pkey, init_val);
+	if (ret) {
+		mm_pkey_free(current->mm, pkey);
+		goto out;
+	}
+	ret = pkey;
+out:
+	mmap_write_unlock(current->mm);
+	return ret;
+}
+
+SYSCALL_DEFINE1(pkey_free, int, pkey)
+{
+	int ret;
+
+	mmap_write_lock(current->mm);
+	ret = mm_pkey_free(current->mm, pkey);
+	mmap_write_unlock(current->mm);
+
+	/*
+	 * We could provide warnings or errors if any VMA still
+	 * has the pkey set here.
+	 */
+	return ret;
+}
+
+#endif /* CONFIG_ARCH_HAS_PKEYS */