/* SPDX-License-Identifier: GPL-2.0 */
#ifndef LINUX_MM_INLINE_H
#define LINUX_MM_INLINE_H

#include <linux/atomic.h>
#include <linux/huge_mm.h>
#include <linux/mm_types.h>
#include <linux/swap.h>
#include <linux/string.h>
#include <linux/userfaultfd_k.h>
#include <linux/leafops.h>

/**
 * folio_is_file_lru - Should the folio be on a file LRU or anon LRU?
 * @folio: The folio to test.
 *
 * We would like to get this info without a page flag, but the state
 * needs to survive until the folio is last deleted from the LRU, which
 * could be as far down as __page_cache_release.
 *
 * Return: An integer (not a boolean!) used to sort a folio onto the
 * right LRU list and to account folios correctly.
 * 1 if @folio is a regular filesystem backed page cache folio
 * or a lazily freed anonymous folio (e.g. via MADV_FREE).
 * 0 if @folio is a normal anonymous folio, a tmpfs folio or otherwise
 * ram or swap backed folio.
 */
static inline int folio_is_file_lru(const struct folio *folio)
{
        return !folio_test_swapbacked(folio);
}

static inline int page_is_file_lru(struct page *page)
{
        return folio_is_file_lru(page_folio(page));
}

static __always_inline void __update_lru_size(struct lruvec *lruvec,
                                enum lru_list lru, enum zone_type zid,
                                long nr_pages)
{
        struct pglist_data *pgdat = lruvec_pgdat(lruvec);

        lockdep_assert_held(&lruvec->lru_lock);
        WARN_ON_ONCE(nr_pages != (int)nr_pages);

        mod_lruvec_state(lruvec, NR_LRU_BASE + lru, nr_pages);
        __mod_zone_page_state(&pgdat->node_zones[zid],
                                NR_ZONE_LRU_BASE + lru, nr_pages);
}

static __always_inline void update_lru_size(struct lruvec *lruvec,
                                enum lru_list lru, enum zone_type zid,
                                long nr_pages)
{
        __update_lru_size(lruvec, lru, zid, nr_pages);
#ifdef CONFIG_MEMCG
        mem_cgroup_update_lru_size(lruvec, lru, zid, nr_pages);
#endif
}

/**
 * __folio_clear_lru_flags - Clear page lru flags before releasing a page.
 * @folio: The folio that was on lru and now has a zero reference.
 */
static __always_inline void __folio_clear_lru_flags(struct folio *folio)
{
        VM_BUG_ON_FOLIO(!folio_test_lru(folio), folio);

        __folio_clear_lru(folio);

        /* this shouldn't happen, so leave the flags to bad_page() */
        if (folio_test_active(folio) && folio_test_unevictable(folio))
                return;

        __folio_clear_active(folio);
        __folio_clear_unevictable(folio);
}

/**
 * folio_lru_list - Which LRU list should a folio be on?
 * @folio: The folio to test.
 *
 * Return: The LRU list a folio should be on, as an index
 * into the array of LRU lists.
 */
static __always_inline enum lru_list folio_lru_list(const struct folio *folio)
{
        enum lru_list lru;

        VM_BUG_ON_FOLIO(folio_test_active(folio) && folio_test_unevictable(folio), folio);

        if (folio_test_unevictable(folio))
                return LRU_UNEVICTABLE;

        lru = folio_is_file_lru(folio) ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON;
        if (folio_test_active(folio))
                lru += LRU_ACTIVE;

        return lru;
}

#ifdef CONFIG_LRU_GEN

#ifdef CONFIG_LRU_GEN_ENABLED
static inline bool lru_gen_enabled(void)
{
        DECLARE_STATIC_KEY_TRUE(lru_gen_caps[NR_LRU_GEN_CAPS]);

        return static_branch_likely(&lru_gen_caps[LRU_GEN_CORE]);
}
#else
static inline bool lru_gen_enabled(void)
{
        DECLARE_STATIC_KEY_FALSE(lru_gen_caps[NR_LRU_GEN_CAPS]);

        return static_branch_unlikely(&lru_gen_caps[LRU_GEN_CORE]);
}
#endif

static inline bool lru_gen_in_fault(void)
{
        return current->in_lru_fault;
}

static inline int lru_gen_from_seq(unsigned long seq)
{
        return seq % MAX_NR_GENS;
}

static inline int lru_hist_from_seq(unsigned long seq)
{
        return seq % NR_HIST_GENS;
}

static inline int lru_tier_from_refs(int refs, bool workingset)
{
        VM_WARN_ON_ONCE(refs > BIT(LRU_REFS_WIDTH));

        /* see the comment on MAX_NR_TIERS */
        return workingset ? MAX_NR_TIERS - 1 : order_base_2(refs);
}

static inline int folio_lru_refs(const struct folio *folio)
{
        unsigned long flags = READ_ONCE(folio->flags.f);

        if (!(flags & BIT(PG_referenced)))
                return 0;
        /*
         * Return the total number of accesses including PG_referenced. Also see
         * the comment on LRU_REFS_FLAGS.
         */
        return ((flags & LRU_REFS_MASK) >> LRU_REFS_PGOFF) + 1;
}

static inline int folio_lru_gen(const struct folio *folio)
{
        unsigned long flags = READ_ONCE(folio->flags.f);

        return ((flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
}

static inline bool lru_gen_is_active(const struct lruvec *lruvec, int gen)
{
        unsigned long max_seq = lruvec->lrugen.max_seq;

        VM_WARN_ON_ONCE(gen >= MAX_NR_GENS);

        /* see the comment on MIN_NR_GENS */
        return gen == lru_gen_from_seq(max_seq) || gen == lru_gen_from_seq(max_seq - 1);
}

static inline void lru_gen_update_size(struct lruvec *lruvec, struct folio *folio,
                                       int old_gen, int new_gen)
{
        int type = folio_is_file_lru(folio);
        int zone = folio_zonenum(folio);
        int delta = folio_nr_pages(folio);
        enum lru_list lru = type * LRU_INACTIVE_FILE;
        struct lru_gen_folio *lrugen = &lruvec->lrugen;

        VM_WARN_ON_ONCE(old_gen != -1 && old_gen >= MAX_NR_GENS);
        VM_WARN_ON_ONCE(new_gen != -1 && new_gen >= MAX_NR_GENS);
        VM_WARN_ON_ONCE(old_gen == -1 && new_gen == -1);

        if (old_gen >= 0)
                WRITE_ONCE(lrugen->nr_pages[old_gen][type][zone],
                           lrugen->nr_pages[old_gen][type][zone] - delta);
        if (new_gen >= 0)
                WRITE_ONCE(lrugen->nr_pages[new_gen][type][zone],
                           lrugen->nr_pages[new_gen][type][zone] + delta);

        /* addition */
        if (old_gen < 0) {
                if (lru_gen_is_active(lruvec, new_gen))
                        lru += LRU_ACTIVE;
                __update_lru_size(lruvec, lru, zone, delta);
                return;
        }

        /* deletion */
        if (new_gen < 0) {
                if (lru_gen_is_active(lruvec, old_gen))
                        lru += LRU_ACTIVE;
                __update_lru_size(lruvec, lru, zone, -delta);
                return;
        }

        /* promotion */
        if (!lru_gen_is_active(lruvec, old_gen) && lru_gen_is_active(lruvec, new_gen)) {
                __update_lru_size(lruvec, lru, zone, -delta);
                __update_lru_size(lruvec, lru + LRU_ACTIVE, zone, delta);
        }

        /* demotion requires isolation, e.g., lru_deactivate_fn() */
        VM_WARN_ON_ONCE(lru_gen_is_active(lruvec, old_gen) && !lru_gen_is_active(lruvec, new_gen));
}

static inline unsigned long lru_gen_folio_seq(const struct lruvec *lruvec,
                                              const struct folio *folio,
                                              bool reclaiming)
{
        int gen;
        int type = folio_is_file_lru(folio);
        const struct lru_gen_folio *lrugen = &lruvec->lrugen;

        /*
         * +-----------------------------------+-----------------------------------+
         * | Accessed through page tables and  | Accessed through file descriptors |
         * | promoted by folio_update_gen()    | and protected by folio_inc_gen()  |
         * +-----------------------------------+-----------------------------------+
         * | PG_active (set while isolated)    |                                   |
         * +-----------------+-----------------+-----------------+-----------------+
         * |  PG_workingset  |  PG_referenced  |  PG_workingset  |  LRU_REFS_FLAGS |
         * +-----------------------------------+-----------------------------------+
         * |<---------- MIN_NR_GENS ---------->|                                   |
         * |<---------------------------- MAX_NR_GENS ---------------------------->|
         */
        if (folio_test_active(folio))
                gen = MIN_NR_GENS - folio_test_workingset(folio);
        else if (reclaiming)
                gen = MAX_NR_GENS;
        else if ((!folio_is_file_lru(folio) && !folio_test_swapcache(folio)) ||
                 (folio_test_reclaim(folio) &&
                  (folio_test_dirty(folio) || folio_test_writeback(folio))))
                gen = MIN_NR_GENS;
        else
                gen = MAX_NR_GENS - folio_test_workingset(folio);

        return max(READ_ONCE(lrugen->max_seq) - gen + 1, READ_ONCE(lrugen->min_seq[type]));
}

static inline bool lru_gen_add_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
{
        unsigned long seq;
        unsigned long flags;
        int gen = folio_lru_gen(folio);
        int type = folio_is_file_lru(folio);
        int zone = folio_zonenum(folio);
        struct lru_gen_folio *lrugen = &lruvec->lrugen;

        VM_WARN_ON_ONCE_FOLIO(gen != -1, folio);

        if (folio_test_unevictable(folio) || !lrugen->enabled)
                return false;

        seq = lru_gen_folio_seq(lruvec, folio, reclaiming);
        gen = lru_gen_from_seq(seq);
        flags = (gen + 1UL) << LRU_GEN_PGOFF;
        /* see the comment on MIN_NR_GENS about PG_active */
        set_mask_bits(&folio->flags.f, LRU_GEN_MASK | BIT(PG_active), flags);

        lru_gen_update_size(lruvec, folio, -1, gen);
        /* for folio_rotate_reclaimable() */
        if (reclaiming)
                list_add_tail(&folio->lru, &lrugen->folios[gen][type][zone]);
        else
                list_add(&folio->lru, &lrugen->folios[gen][type][zone]);

        return true;
}

static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
{
        unsigned long flags;
        int gen = folio_lru_gen(folio);

        if (gen < 0)
                return false;

        VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio);
        VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);

        /* for folio_migrate_flags() */
        flags = !reclaiming && lru_gen_is_active(lruvec, gen) ? BIT(PG_active) : 0;
        flags = set_mask_bits(&folio->flags.f, LRU_GEN_MASK, flags);
        gen = ((flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;

        lru_gen_update_size(lruvec, folio, gen, -1);
        list_del(&folio->lru);

        return true;
}

static inline void folio_migrate_refs(struct folio *new, const struct folio *old)
{
        unsigned long refs = READ_ONCE(old->flags.f) & LRU_REFS_MASK;

        set_mask_bits(&new->flags.f, LRU_REFS_MASK, refs);
}
#else /* !CONFIG_LRU_GEN */

static inline bool lru_gen_enabled(void)
{
        return false;
}

static inline bool lru_gen_in_fault(void)
{
        return false;
}

static inline bool lru_gen_add_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
{
        return false;
}

static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
{
        return false;
}

static inline void folio_migrate_refs(struct folio *new, const struct folio *old)
{

}
#endif /* CONFIG_LRU_GEN */

static __always_inline
void lruvec_add_folio(struct lruvec *lruvec, struct folio *folio)
{
        enum lru_list lru = folio_lru_list(folio);

        if (lru_gen_add_folio(lruvec, folio, false))
                return;

        update_lru_size(lruvec, lru, folio_zonenum(folio),
                        folio_nr_pages(folio));
        if (lru != LRU_UNEVICTABLE)
                list_add(&folio->lru, &lruvec->lists[lru]);
}

static __always_inline
void lruvec_add_folio_tail(struct lruvec *lruvec, struct folio *folio)
{
        enum lru_list lru = folio_lru_list(folio);

        if (lru_gen_add_folio(lruvec, folio, true))
                return;

        update_lru_size(lruvec, lru, folio_zonenum(folio),
                        folio_nr_pages(folio));
        /* This is not expected to be used on LRU_UNEVICTABLE */
        list_add_tail(&folio->lru, &lruvec->lists[lru]);
}

static __always_inline
void lruvec_del_folio(struct lruvec *lruvec, struct folio *folio)
{
        enum lru_list lru = folio_lru_list(folio);

        if (lru_gen_del_folio(lruvec, folio, false))
                return;

        if (lru != LRU_UNEVICTABLE)
                list_del(&folio->lru);
        update_lru_size(lruvec, lru, folio_zonenum(folio),
                        -folio_nr_pages(folio));
}

#ifdef CONFIG_ANON_VMA_NAME
/* mmap_lock should be read-locked */
static inline void anon_vma_name_get(struct anon_vma_name *anon_name)
{
        if (anon_name)
                kref_get(&anon_name->kref);
}

static inline void anon_vma_name_put(struct anon_vma_name *anon_name)
{
        if (anon_name)
                kref_put(&anon_name->kref, anon_vma_name_free);
}

static inline
struct anon_vma_name *anon_vma_name_reuse(struct anon_vma_name *anon_name)
{
        /* Prevent anon_name refcount saturation early on */
        if (kref_read(&anon_name->kref) < REFCOUNT_MAX) {
                anon_vma_name_get(anon_name);
                return anon_name;

        }
        return anon_vma_name_alloc(anon_name->name);
}

static inline void dup_anon_vma_name(struct vm_area_struct *orig_vma,
                                     struct vm_area_struct *new_vma)
{
        struct anon_vma_name *anon_name = anon_vma_name(orig_vma);

        if (anon_name)
                new_vma->anon_name = anon_vma_name_reuse(anon_name);
}

static inline void free_anon_vma_name(struct vm_area_struct *vma)
{
        /*
         * Not using anon_vma_name because it generates a warning if mmap_lock
         * is not held, which might be the case here.
         */
        anon_vma_name_put(vma->anon_name);
}

static inline bool anon_vma_name_eq(struct anon_vma_name *anon_name1,
                                    struct anon_vma_name *anon_name2)
{
        if (anon_name1 == anon_name2)
                return true;

        return anon_name1 && anon_name2 &&
                !strcmp(anon_name1->name, anon_name2->name);
}

#else /* CONFIG_ANON_VMA_NAME */
static inline void anon_vma_name_get(struct anon_vma_name *anon_name) {}
static inline void anon_vma_name_put(struct anon_vma_name *anon_name) {}
static inline void dup_anon_vma_name(struct vm_area_struct *orig_vma,
                                     struct vm_area_struct *new_vma) {}
static inline void free_anon_vma_name(struct vm_area_struct *vma) {}

static inline bool anon_vma_name_eq(struct anon_vma_name *anon_name1,
                                    struct anon_vma_name *anon_name2)
{
        return true;
}

#endif  /* CONFIG_ANON_VMA_NAME */

void pfnmap_track_ctx_release(struct kref *ref);

static inline void init_tlb_flush_pending(struct mm_struct *mm)
{
        atomic_set(&mm->tlb_flush_pending, 0);
}

static inline void inc_tlb_flush_pending(struct mm_struct *mm)
{
        atomic_inc(&mm->tlb_flush_pending);
        /*
         * The only time this value is relevant is when there are indeed pages
         * to flush. And we'll only flush pages after changing them, which
         * requires the PTL.
         *
         * So the ordering here is:
         *
         *      atomic_inc(&mm->tlb_flush_pending);
         *      spin_lock(&ptl);
         *      ...
         *      set_pte_at();
         *      spin_unlock(&ptl);
         *
         *                              spin_lock(&ptl)
         *                              mm_tlb_flush_pending();
         *                              ....
         *                              spin_unlock(&ptl);
         *
         *      flush_tlb_range();
         *      atomic_dec(&mm->tlb_flush_pending);
         *
         * Where the increment if constrained by the PTL unlock, it thus
         * ensures that the increment is visible if the PTE modification is
         * visible. After all, if there is no PTE modification, nobody cares
         * about TLB flushes either.
         *
         * This very much relies on users (mm_tlb_flush_pending() and
         * mm_tlb_flush_nested()) only caring about _specific_ PTEs (and
         * therefore specific PTLs), because with SPLIT_PTE_PTLOCKS and RCpc
         * locks (PPC) the unlock of one doesn't order against the lock of
         * another PTL.
         *
         * The decrement is ordered by the flush_tlb_range(), such that
         * mm_tlb_flush_pending() will not return false unless all flushes have
         * completed.
         */
}

static inline void dec_tlb_flush_pending(struct mm_struct *mm)
{
        /*
         * See inc_tlb_flush_pending().
         *
         * This cannot be smp_mb__before_atomic() because smp_mb() simply does
         * not order against TLB invalidate completion, which is what we need.
         *
         * Therefore we must rely on tlb_flush_*() to guarantee order.
         */
        atomic_dec(&mm->tlb_flush_pending);
}

static inline bool mm_tlb_flush_pending(const struct mm_struct *mm)
{
        /*
         * Must be called after having acquired the PTL; orders against that
         * PTLs release and therefore ensures that if we observe the modified
         * PTE we must also observe the increment from inc_tlb_flush_pending().
         *
         * That is, it only guarantees to return true if there is a flush
         * pending for _this_ PTL.
         */
        return atomic_read(&mm->tlb_flush_pending);
}

static inline bool mm_tlb_flush_nested(const struct mm_struct *mm)
{
        /*
         * Similar to mm_tlb_flush_pending(), we must have acquired the PTL
         * for which there is a TLB flush pending in order to guarantee
         * we've seen both that PTE modification and the increment.
         *
         * (no requirement on actually still holding the PTL, that is irrelevant)
         */
        return atomic_read(&mm->tlb_flush_pending) > 1;
}

#ifdef CONFIG_MMU
/*
 * Computes the pte marker to copy from the given source entry into dst_vma.
 * If no marker should be copied, returns 0.
 * The caller should insert a new pte created with make_pte_marker().
 */
static inline pte_marker copy_pte_marker(
                softleaf_t entry, struct vm_area_struct *dst_vma)
{
        const pte_marker srcm = softleaf_to_marker(entry);
        /* Always copy error entries. */
        pte_marker dstm = srcm & (PTE_MARKER_POISONED | PTE_MARKER_GUARD);

        /* Only copy PTE markers if UFFD register matches. */
        if ((srcm & PTE_MARKER_UFFD_WP) && userfaultfd_wp(dst_vma))
                dstm |= PTE_MARKER_UFFD_WP;

        return dstm;
}

/*
 * If this pte is wr-protected by uffd-wp in any form, arm the special pte to
 * replace a none pte.  NOTE!  This should only be called when *pte is already
 * cleared so we will never accidentally replace something valuable.  Meanwhile
 * none pte also means we are not demoting the pte so tlb flushed is not needed.
 * E.g., when pte cleared the caller should have taken care of the tlb flush.
 *
 * Must be called with pgtable lock held so that no thread will see the none
 * pte, and if they see it, they'll fault and serialize at the pgtable lock.
 *
 * Returns true if an uffd-wp pte was installed, false otherwise.
 */
static inline bool
pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr,
                              pte_t *pte, pte_t pteval)
{
        bool arm_uffd_pte = false;

        if (!uffd_supports_wp_marker())
                return false;

        /* The current status of the pte should be "cleared" before calling */
        WARN_ON_ONCE(!pte_none(ptep_get(pte)));

        /*
         * NOTE: userfaultfd_wp_unpopulated() doesn't need this whole
         * thing, because when zapping either it means it's dropping the
         * page, or in TTU where the present pte will be quickly replaced
         * with a swap pte.  There's no way of leaking the bit.
         */
        if (vma_is_anonymous(vma) || !userfaultfd_wp(vma))
                return false;

        /* A uffd-wp wr-protected normal pte */
        if (unlikely(pte_present(pteval) && pte_uffd_wp(pteval)))
                arm_uffd_pte = true;

        /*
         * A uffd-wp wr-protected swap pte.  Note: this should even cover an
         * existing pte marker with uffd-wp bit set.
         */
        if (unlikely(pte_swp_uffd_wp_any(pteval)))
                arm_uffd_pte = true;

        if (unlikely(arm_uffd_pte)) {
                set_pte_at(vma->vm_mm, addr, pte,
                           make_pte_marker(PTE_MARKER_UFFD_WP));
                return true;
        }

        return false;
}

static inline bool vma_has_recency(const struct vm_area_struct *vma)
{
        if (vma->vm_flags & (VM_SEQ_READ | VM_RAND_READ))
                return false;

        if (vma->vm_file && (vma->vm_file->f_mode & FMODE_NOREUSE))
                return false;

        return true;
}
#endif

/**
 * num_pages_contiguous() - determine the number of contiguous pages
 *                          that represent contiguous PFNs
 * @pages: an array of page pointers
 * @nr_pages: length of the array, at least 1
 *
 * Determine the number of contiguous pages that represent contiguous PFNs
 * in @pages, starting from the first page.
 *
 * In some kernel configs contiguous PFNs will not have contiguous struct
 * pages. In these configurations num_pages_contiguous() will return a num
 * smaller than ideal number. The caller should continue to check for pfn
 * contiguity after each call to num_pages_contiguous().
 *
 * Returns the number of contiguous pages.
 */
static inline size_t num_pages_contiguous(struct page **pages, size_t nr_pages)
{
        struct page *cur_page = pages[0];
        unsigned long section = memdesc_section(cur_page->flags);
        size_t i;

        for (i = 1; i < nr_pages; i++) {
                if (++cur_page != pages[i])
                        break;
                /*
                 * In unproblematic kernel configs, page_to_section() == 0 and
                 * the whole check will get optimized out.
                 */
                if (memdesc_section(cur_page->flags) != section)
                        break;
        }

        return i;
}

#endif