// 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/userfaultfd_k.h>
#include <uapi/linux/mman.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
#include <asm/tlbflush.h>
#include <asm/tlb.h>

#include "internal.h"

static bool maybe_change_pte_writable(struct vm_area_struct *vma, pte_t pte)
{
        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 (pte_needs_soft_dirty_wp(vma, pte))
                return false;

        /* Do we need write faults for uffd-wp tracking? */
        if (userfaultfd_pte_wp(vma, pte))
                return false;

        return true;
}

static bool can_change_private_pte_writable(struct vm_area_struct *vma,
                                            unsigned long addr, pte_t pte)
{
        struct page *page;

        if (!maybe_change_pte_writable(vma, pte))
                return false;

        /*
         * 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);
}

static bool can_change_shared_pte_writable(struct vm_area_struct *vma,
                                           pte_t pte)
{
        if (!maybe_change_pte_writable(vma, pte))
                return false;

        VM_WARN_ON_ONCE(is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte));

        /*
         * 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);
}

bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
                             pte_t pte)
{
        if (!(vma->vm_flags & VM_SHARED))
                return can_change_private_pte_writable(vma, addr, pte);

        return can_change_shared_pte_writable(vma, pte);
}

static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep,
                                    pte_t pte, int max_nr_ptes, fpb_t flags)
{
        /* No underlying folio, so cannot batch */
        if (!folio)
                return 1;

        if (!folio_test_large(folio))
                return 1;

        return folio_pte_batch_flags(folio, NULL, ptep, &pte, max_nr_ptes, flags);
}

/* Set nr_ptes number of ptes, starting from idx */
static void prot_commit_flush_ptes(struct vm_area_struct *vma, unsigned long addr,
                pte_t *ptep, pte_t oldpte, pte_t ptent, int nr_ptes,
                int idx, bool set_write, struct mmu_gather *tlb)
{
        /*
         * Advance the position in the batch by idx; note that if idx > 0,
         * then the nr_ptes passed here is <= batch size - idx.
         */
        addr += idx * PAGE_SIZE;
        ptep += idx;
        oldpte = pte_advance_pfn(oldpte, idx);
        ptent = pte_advance_pfn(ptent, idx);

        if (set_write)
                ptent = pte_mkwrite(ptent, vma);

        modify_prot_commit_ptes(vma, addr, ptep, oldpte, ptent, nr_ptes);
        if (pte_needs_flush(oldpte, ptent))
                tlb_flush_pte_range(tlb, addr, nr_ptes * PAGE_SIZE);
}

/*
 * Get max length of consecutive ptes pointing to PageAnonExclusive() pages or
 * !PageAnonExclusive() pages, starting from start_idx. Caller must enforce
 * that the ptes point to consecutive pages of the same anon large folio.
 */
static int page_anon_exclusive_sub_batch(int start_idx, int max_len,
                struct page *first_page, bool expected_anon_exclusive)
{
        int idx;

        for (idx = start_idx + 1; idx < start_idx + max_len; ++idx) {
                if (expected_anon_exclusive != PageAnonExclusive(first_page + idx))
                        break;
        }
        return idx - start_idx;
}

/*
 * This function is a result of trying our very best to retain the
 * "avoid the write-fault handler" optimization. In can_change_pte_writable(),
 * if the vma is a private vma, and we cannot determine whether to change
 * the pte to writable just from the vma and the pte, we then need to look
 * at the actual page pointed to by the pte. Unfortunately, if we have a
 * batch of ptes pointing to consecutive pages of the same anon large folio,
 * the anon-exclusivity (or the negation) of the first page does not guarantee
 * the anon-exclusivity (or the negation) of the other pages corresponding to
 * the pte batch; hence in this case it is incorrect to decide to change or
 * not change the ptes to writable just by using information from the first
 * pte of the batch. Therefore, we must individually check all pages and
 * retrieve sub-batches.
 */
static void commit_anon_folio_batch(struct vm_area_struct *vma,
                struct folio *folio, struct page *first_page, unsigned long addr, pte_t *ptep,
                pte_t oldpte, pte_t ptent, int nr_ptes, struct mmu_gather *tlb)
{
        bool expected_anon_exclusive;
        int sub_batch_idx = 0;
        int len;

        while (nr_ptes) {
                expected_anon_exclusive = PageAnonExclusive(first_page + sub_batch_idx);
                len = page_anon_exclusive_sub_batch(sub_batch_idx, nr_ptes,
                                        first_page, expected_anon_exclusive);
                prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, len,
                                       sub_batch_idx, expected_anon_exclusive, tlb);
                sub_batch_idx += len;
                nr_ptes -= len;
        }
}

static void set_write_prot_commit_flush_ptes(struct vm_area_struct *vma,
                struct folio *folio, struct page *page, unsigned long addr, pte_t *ptep,
                pte_t oldpte, pte_t ptent, int nr_ptes, struct mmu_gather *tlb)
{
        bool set_write;

        if (vma->vm_flags & VM_SHARED) {
                set_write = can_change_shared_pte_writable(vma, ptent);
                prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, nr_ptes,
                                       /* idx = */ 0, set_write, tlb);
                return;
        }

        set_write = maybe_change_pte_writable(vma, ptent) &&
                    (folio && folio_test_anon(folio));
        if (!set_write) {
                prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, nr_ptes,
                                       /* idx = */ 0, set_write, tlb);
                return;
        }
        commit_anon_folio_batch(vma, folio, page, addr, ptep, oldpte, ptent, nr_ptes, tlb);
}

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;
        bool is_private_single_threaded;
        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;
        int nr_ptes;

        tlb_change_page_size(tlb, PAGE_SIZE);
        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
        if (!pte)
                return -EAGAIN;

        if (prot_numa)
                is_private_single_threaded = vma_is_single_threaded_private(vma);

        flush_tlb_batched_pending(vma->vm_mm);
        lazy_mmu_mode_enable();
        do {
                nr_ptes = 1;
                oldpte = ptep_get(pte);
                if (pte_present(oldpte)) {
                        const fpb_t flags = FPB_RESPECT_SOFT_DIRTY | FPB_RESPECT_WRITE;
                        int max_nr_ptes = (end - addr) >> PAGE_SHIFT;
                        struct folio *folio = NULL;
                        struct page *page;
                        pte_t ptent;

                        /* Already in the desired state. */
                        if (prot_numa && pte_protnone(oldpte))
                                continue;

                        page = vm_normal_page(vma, addr, oldpte);
                        if (page)
                                folio = page_folio(page);

                        /*
                         * Avoid trapping faults against the zero or KSM
                         * pages. See similar comment in change_huge_pmd.
                         */
                        if (prot_numa &&
                            !folio_can_map_prot_numa(folio, vma,
                                                is_private_single_threaded)) {

                                /* determine batch to skip */
                                nr_ptes = mprotect_folio_pte_batch(folio,
                                          pte, oldpte, max_nr_ptes, /* flags = */ 0);
                                continue;
                        }

                        nr_ptes = mprotect_folio_pte_batch(folio, pte, oldpte, max_nr_ptes, flags);

                        oldpte = modify_prot_start_ptes(vma, addr, pte, nr_ptes);
                        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))
                                set_write_prot_commit_flush_ptes(vma, folio, page,
                                addr, pte, oldpte, ptent, nr_ptes, tlb);
                        else
                                prot_commit_flush_ptes(vma, addr, pte, oldpte, ptent,
                                        nr_ptes, /* idx = */ 0, /* set_write = */ false, tlb);
                        pages += nr_ptes;
                } else if (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++;
                        }
                } else  {
                        softleaf_t entry = softleaf_from_pte(oldpte);
                        pte_t newpte;

                        if (softleaf_is_migration_write(entry)) {
                                const struct folio *folio = softleaf_to_folio(entry);

                                /*
                                 * A protection check is difficult so
                                 * just be safe and disable write
                                 */
                                if (folio_test_anon(folio))
                                        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 (softleaf_is_device_private_write(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 (softleaf_is_marker(entry)) {
                                /*
                                 * Ignore error swap entries unconditionally,
                                 * because any access should sigbus/sigsegv
                                 * anyway.
                                 */
                                if (softleaf_is_poison_marker(entry) ||
                                    softleaf_is_guard_marker(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++;
                        }
                }
        } while (pte += nr_ptes, addr += nr_ptes * PAGE_SIZE, addr != end);
        lazy_mmu_mode_disable();
        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.  For example, we cannot wr-protect a file thp
         * (e.g. 2M shmem) 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;

        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;

                _pmd = pmdp_get_lockless(pmd);
                if (pmd_is_huge(_pmd)) {
                        if ((next - addr != HPAGE_PMD_SIZE) ||
                            pgtable_split_needed(vma, cp_flags)) {
                                __split_huge_pmd(vma, pmd, addr, false);
                                /*
                                 * 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 (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)
{
        struct mmu_notifier_range range;
        pud_t *pudp, pud;
        unsigned long next;
        long pages = 0, ret;

        range.start = 0;

        pudp = pud_offset(p4d, addr);
        do {
again:
                next = pud_addr_end(addr, end);
                ret = change_prepare(vma, pudp, pmd, addr, cp_flags);
                if (ret) {
                        pages = ret;
                        break;
                }

                pud = pudp_get(pudp);
                if (pud_none(pud))
                        continue;

                if (!range.start) {
                        mmu_notifier_range_init(&range,
                                                MMU_NOTIFY_PROTECTION_VMA, 0,
                                                vma->vm_mm, addr, end);
                        mmu_notifier_invalidate_range_start(&range);
                }

                if (pud_leaf(pud)) {
                        if ((next - addr != PUD_SIZE) ||
                            pgtable_split_needed(vma, cp_flags)) {
                                __split_huge_pud(vma, pudp, addr);
                                goto again;
                        } else {
                                ret = change_huge_pud(tlb, vma, pudp,
                                                      addr, newprot, cp_flags);
                                if (ret == 0)
                                        goto again;
                                /* huge pud was handled */
                                if (ret == HPAGE_PUD_NR)
                                        pages += HPAGE_PUD_NR;
                                continue;
                        }
                }

                pages += change_pmd_range(tlb, vma, pudp, addr, next, newprot,
                                          cp_flags);
        } while (pudp++, addr = next, addr != end);

        if (range.start)
                mmu_notifier_invalidate_range_end(&range);

        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, vm_flags_t newflags)
{
        struct mm_struct *mm = vma->vm_mm;
        vm_flags_t oldflags = READ_ONCE(vma->vm_flags);
        long nrpages = (end - start) >> PAGE_SHIFT;
        unsigned int mm_cp_flags = 0;
        unsigned long charged = 0;
        int error;

        if (vma_is_sealed(vma))
                return -EPERM;

        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() &&
            (oldflags & (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 except in the anonymous case where no
         * anon_vma has yet to be assigned.
         *
         * 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;
                }
        } else if ((oldflags & VM_ACCOUNT) && vma_is_anonymous(vma) &&
                   !vma->anon_vma) {
                newflags &= ~VM_ACCOUNT;
        }

        vma = vma_modify_flags(vmi, *pprev, vma, start, end, &newflags);
        if (IS_ERR(vma)) {
                error = PTR_ERR(vma);
                goto fail;
        }

        *pprev = vma;

        /*
         * vm_flags and vm_page_prot are protected by the mmap_lock
         * held in write mode.
         */
        vma_start_write(vma);
        vm_flags_reset_once(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);

        if ((oldflags & VM_ACCOUNT) && !(newflags & VM_ACCOUNT))
                vm_unacct_memory(nrpages);

        /*
         * 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) {
                vm_flags_t mask_off_old_flags;
                vm_flags_t 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->vm_flags, 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 */