// SPDX-License-Identifier: GPL-2.0
#include <linux/pagewalk.h>
#include <linux/vmacache.h>
#include <linux/hugetlb.h>
#include <linux/huge_mm.h>
#include <linux/mount.h>
#include <linux/seq_file.h>
#include <linux/highmem.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/mempolicy.h>
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/sched/mm.h>
#include <linux/swapops.h>
#include <linux/mmu_notifier.h>
#include <linux/page_idle.h>
#include <linux/shmem_fs.h>
#include <linux/uaccess.h>
#include <linux/pkeys.h>

#include <asm/elf.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include "internal.h"

#define SEQ_PUT_DEC(str, val) \
                seq_put_decimal_ull_width(m, str, (val) << (PAGE_SHIFT-10), 8)
void task_mem(struct seq_file *m, struct mm_struct *mm)
{
        unsigned long text, lib, swap, anon, file, shmem;
        unsigned long hiwater_vm, total_vm, hiwater_rss, total_rss;

        anon = get_mm_counter(mm, MM_ANONPAGES);
        file = get_mm_counter(mm, MM_FILEPAGES);
        shmem = get_mm_counter(mm, MM_SHMEMPAGES);

        /*
         * Note: to minimize their overhead, mm maintains hiwater_vm and
         * hiwater_rss only when about to *lower* total_vm or rss.  Any
         * collector of these hiwater stats must therefore get total_vm
         * and rss too, which will usually be the higher.  Barriers? not
         * worth the effort, such snapshots can always be inconsistent.
         */
        hiwater_vm = total_vm = mm->total_vm;
        if (hiwater_vm < mm->hiwater_vm)
                hiwater_vm = mm->hiwater_vm;
        hiwater_rss = total_rss = anon + file + shmem;
        if (hiwater_rss < mm->hiwater_rss)
                hiwater_rss = mm->hiwater_rss;

        /* split executable areas between text and lib */
        text = PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK);
        text = min(text, mm->exec_vm << PAGE_SHIFT);
        lib = (mm->exec_vm << PAGE_SHIFT) - text;

        swap = get_mm_counter(mm, MM_SWAPENTS);
        SEQ_PUT_DEC("VmPeak:\t", hiwater_vm);
        SEQ_PUT_DEC(" kB\nVmSize:\t", total_vm);
        SEQ_PUT_DEC(" kB\nVmLck:\t", mm->locked_vm);
        SEQ_PUT_DEC(" kB\nVmPin:\t", atomic64_read(&mm->pinned_vm));
        SEQ_PUT_DEC(" kB\nVmHWM:\t", hiwater_rss);
        SEQ_PUT_DEC(" kB\nVmRSS:\t", total_rss);
        SEQ_PUT_DEC(" kB\nRssAnon:\t", anon);
        SEQ_PUT_DEC(" kB\nRssFile:\t", file);
        SEQ_PUT_DEC(" kB\nRssShmem:\t", shmem);
        SEQ_PUT_DEC(" kB\nVmData:\t", mm->data_vm);
        SEQ_PUT_DEC(" kB\nVmStk:\t", mm->stack_vm);
        seq_put_decimal_ull_width(m,
                    " kB\nVmExe:\t", text >> 10, 8);
        seq_put_decimal_ull_width(m,
                    " kB\nVmLib:\t", lib >> 10, 8);
        seq_put_decimal_ull_width(m,
                    " kB\nVmPTE:\t", mm_pgtables_bytes(mm) >> 10, 8);
        SEQ_PUT_DEC(" kB\nVmSwap:\t", swap);
        seq_puts(m, " kB\n");
        hugetlb_report_usage(m, mm);
}
#undef SEQ_PUT_DEC

unsigned long task_vsize(struct mm_struct *mm)
{
        return PAGE_SIZE * mm->total_vm;
}

unsigned long task_statm(struct mm_struct *mm,
                         unsigned long *shared, unsigned long *text,
                         unsigned long *data, unsigned long *resident)
{
        *shared = get_mm_counter(mm, MM_FILEPAGES) +
                        get_mm_counter(mm, MM_SHMEMPAGES);
        *text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK))
                                                                >> PAGE_SHIFT;
        *data = mm->data_vm + mm->stack_vm;
        *resident = *shared + get_mm_counter(mm, MM_ANONPAGES);
        return mm->total_vm;
}

#ifdef CONFIG_NUMA
/*
 * Save get_task_policy() for show_numa_map().
 */
static void hold_task_mempolicy(struct proc_maps_private *priv)
{
        struct task_struct *task = priv->task;

        task_lock(task);
        priv->task_mempolicy = get_task_policy(task);
        mpol_get(priv->task_mempolicy);
        task_unlock(task);
}
static void release_task_mempolicy(struct proc_maps_private *priv)
{
        mpol_put(priv->task_mempolicy);
}
#else
static void hold_task_mempolicy(struct proc_maps_private *priv)
{
}
static void release_task_mempolicy(struct proc_maps_private *priv)
{
}
#endif

static void *m_start(struct seq_file *m, loff_t *ppos)
{
        struct proc_maps_private *priv = m->private;
        unsigned long last_addr = *ppos;
        struct mm_struct *mm;
        struct vm_area_struct *vma;

        /* See m_next(). Zero at the start or after lseek. */
        if (last_addr == -1UL)
                return NULL;

        priv->task = get_proc_task(priv->inode);
        if (!priv->task)
                return ERR_PTR(-ESRCH);

        mm = priv->mm;
        if (!mm || !mmget_not_zero(mm)) {
                put_task_struct(priv->task);
                priv->task = NULL;
                return NULL;
        }

        if (mmap_read_lock_killable(mm)) {
                mmput(mm);
                put_task_struct(priv->task);
                priv->task = NULL;
                return ERR_PTR(-EINTR);
        }

        hold_task_mempolicy(priv);
        priv->tail_vma = get_gate_vma(mm);

        vma = find_vma(mm, last_addr);
        if (vma)
                return vma;

        return priv->tail_vma;
}

static void *m_next(struct seq_file *m, void *v, loff_t *ppos)
{
        struct proc_maps_private *priv = m->private;
        struct vm_area_struct *next, *vma = v;

        if (vma == priv->tail_vma)
                next = NULL;
        else if (vma->vm_next)
                next = vma->vm_next;
        else
                next = priv->tail_vma;

        *ppos = next ? next->vm_start : -1UL;

        return next;
}

static void m_stop(struct seq_file *m, void *v)
{
        struct proc_maps_private *priv = m->private;
        struct mm_struct *mm = priv->mm;

        if (!priv->task)
                return;

        release_task_mempolicy(priv);
        mmap_read_unlock(mm);
        mmput(mm);
        put_task_struct(priv->task);
        priv->task = NULL;
}

static int proc_maps_open(struct inode *inode, struct file *file,
                        const struct seq_operations *ops, int psize)
{
        struct proc_maps_private *priv = __seq_open_private(file, ops, psize);

        if (!priv)
                return -ENOMEM;

        priv->inode = inode;
        priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
        if (IS_ERR(priv->mm)) {
                int err = PTR_ERR(priv->mm);

                seq_release_private(inode, file);
                return err;
        }

        return 0;
}

static int proc_map_release(struct inode *inode, struct file *file)
{
        struct seq_file *seq = file->private_data;
        struct proc_maps_private *priv = seq->private;

        if (priv->mm)
                mmdrop(priv->mm);

        return seq_release_private(inode, file);
}

static int do_maps_open(struct inode *inode, struct file *file,
                        const struct seq_operations *ops)
{
        return proc_maps_open(inode, file, ops,
                                sizeof(struct proc_maps_private));
}

/*
 * Indicate if the VMA is a stack for the given task; for
 * /proc/PID/maps that is the stack of the main task.
 */
static int is_stack(struct vm_area_struct *vma)
{
        /*
         * We make no effort to guess what a given thread considers to be
         * its "stack".  It's not even well-defined for programs written
         * languages like Go.
         */
        return vma->vm_start <= vma->vm_mm->start_stack &&
                vma->vm_end >= vma->vm_mm->start_stack;
}

static void show_vma_header_prefix(struct seq_file *m,
                                   unsigned long start, unsigned long end,
                                   vm_flags_t flags, unsigned long long pgoff,
                                   dev_t dev, unsigned long ino)
{
        seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
        seq_put_hex_ll(m, NULL, start, 8);
        seq_put_hex_ll(m, "-", end, 8);
        seq_putc(m, ' ');
        seq_putc(m, flags & VM_READ ? 'r' : '-');
        seq_putc(m, flags & VM_WRITE ? 'w' : '-');
        seq_putc(m, flags & VM_EXEC ? 'x' : '-');
        seq_putc(m, flags & VM_MAYSHARE ? 's' : 'p');
        seq_put_hex_ll(m, " ", pgoff, 8);
        seq_put_hex_ll(m, " ", MAJOR(dev), 2);
        seq_put_hex_ll(m, ":", MINOR(dev), 2);
        seq_put_decimal_ull(m, " ", ino);
        seq_putc(m, ' ');
}

static void
show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
{
        struct mm_struct *mm = vma->vm_mm;
        struct file *file = vma->vm_file;
        vm_flags_t flags = vma->vm_flags;
        unsigned long ino = 0;
        unsigned long long pgoff = 0;
        unsigned long start, end;
        dev_t dev = 0;
        const char *name = NULL;

        if (file) {
                struct inode *inode = file_inode(vma->vm_file);
                dev = inode->i_sb->s_dev;
                ino = inode->i_ino;
                pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT;
        }

        start = vma->vm_start;
        end = vma->vm_end;
        show_vma_header_prefix(m, start, end, flags, pgoff, dev, ino);

        /*
         * Print the dentry name for named mappings, and a
         * special [heap] marker for the heap:
         */
        if (file) {
                seq_pad(m, ' ');
                seq_file_path(m, file, "\n");
                goto done;
        }

        if (vma->vm_ops && vma->vm_ops->name) {
                name = vma->vm_ops->name(vma);
                if (name)
                        goto done;
        }

        name = arch_vma_name(vma);
        if (!name) {
                if (!mm) {
                        name = "[vdso]";
                        goto done;
                }

                if (vma->vm_start <= mm->brk &&
                    vma->vm_end >= mm->start_brk) {
                        name = "[heap]";
                        goto done;
                }

                if (is_stack(vma))
                        name = "[stack]";
        }

done:
        if (name) {
                seq_pad(m, ' ');
                seq_puts(m, name);
        }
        seq_putc(m, '\n');
}

static int show_map(struct seq_file *m, void *v)
{
        show_map_vma(m, v);
        return 0;
}

static const struct seq_operations proc_pid_maps_op = {
        .start  = m_start,
        .next   = m_next,
        .stop   = m_stop,
        .show   = show_map
};

static int pid_maps_open(struct inode *inode, struct file *file)
{
        return do_maps_open(inode, file, &proc_pid_maps_op);
}

const struct file_operations proc_pid_maps_operations = {
        .open           = pid_maps_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = proc_map_release,
};

/*
 * Proportional Set Size(PSS): my share of RSS.
 *
 * PSS of a process is the count of pages it has in memory, where each
 * page is divided by the number of processes sharing it.  So if a
 * process has 1000 pages all to itself, and 1000 shared with one other
 * process, its PSS will be 1500.
 *
 * To keep (accumulated) division errors low, we adopt a 64bit
 * fixed-point pss counter to minimize division errors. So (pss >>
 * PSS_SHIFT) would be the real byte count.
 *
 * A shift of 12 before division means (assuming 4K page size):
 *      - 1M 3-user-pages add up to 8KB errors;
 *      - supports mapcount up to 2^24, or 16M;
 *      - supports PSS up to 2^52 bytes, or 4PB.
 */
#define PSS_SHIFT 12

#ifdef CONFIG_PROC_PAGE_MONITOR
struct mem_size_stats {
        unsigned long resident;
        unsigned long shared_clean;
        unsigned long shared_dirty;
        unsigned long private_clean;
        unsigned long private_dirty;
        unsigned long referenced;
        unsigned long anonymous;
        unsigned long lazyfree;
        unsigned long anonymous_thp;
        unsigned long shmem_thp;
        unsigned long file_thp;
        unsigned long swap;
        unsigned long shared_hugetlb;
        unsigned long private_hugetlb;
        u64 pss;
        u64 pss_anon;
        u64 pss_file;
        u64 pss_shmem;
        u64 pss_locked;
        u64 swap_pss;
        bool check_shmem_swap;
};

static void smaps_page_accumulate(struct mem_size_stats *mss,
                struct page *page, unsigned long size, unsigned long pss,
                bool dirty, bool locked, bool private)
{
        mss->pss += pss;

        if (PageAnon(page))
                mss->pss_anon += pss;
        else if (PageSwapBacked(page))
                mss->pss_shmem += pss;
        else
                mss->pss_file += pss;

        if (locked)
                mss->pss_locked += pss;

        if (dirty || PageDirty(page)) {
                if (private)
                        mss->private_dirty += size;
                else
                        mss->shared_dirty += size;
        } else {
                if (private)
                        mss->private_clean += size;
                else
                        mss->shared_clean += size;
        }
}

static void smaps_account(struct mem_size_stats *mss, struct page *page,
                bool compound, bool young, bool dirty, bool locked)
{
        int i, nr = compound ? compound_nr(page) : 1;
        unsigned long size = nr * PAGE_SIZE;

        /*
         * First accumulate quantities that depend only on |size| and the type
         * of the compound page.
         */
        if (PageAnon(page)) {
                mss->anonymous += size;
                if (!PageSwapBacked(page) && !dirty && !PageDirty(page))
                        mss->lazyfree += size;
        }

        mss->resident += size;
        /* Accumulate the size in pages that have been accessed. */
        if (young || page_is_young(page) || PageReferenced(page))
                mss->referenced += size;

        /*
         * Then accumulate quantities that may depend on sharing, or that may
         * differ page-by-page.
         *
         * page_count(page) == 1 guarantees the page is mapped exactly once.
         * If any subpage of the compound page mapped with PTE it would elevate
         * page_count().
         */
        if (page_count(page) == 1) {
                smaps_page_accumulate(mss, page, size, size << PSS_SHIFT, dirty,
                        locked, true);
                return;
        }
        for (i = 0; i < nr; i++, page++) {
                int mapcount = page_mapcount(page);
                unsigned long pss = PAGE_SIZE << PSS_SHIFT;
                if (mapcount >= 2)
                        pss /= mapcount;
                smaps_page_accumulate(mss, page, PAGE_SIZE, pss, dirty, locked,
                                      mapcount < 2);
        }
}

#ifdef CONFIG_SHMEM
static int smaps_pte_hole(unsigned long addr, unsigned long end,
                          __always_unused int depth, struct mm_walk *walk)
{
        struct mem_size_stats *mss = walk->private;

        mss->swap += shmem_partial_swap_usage(
                        walk->vma->vm_file->f_mapping, addr, end);

        return 0;
}
#else
#define smaps_pte_hole          NULL
#endif /* CONFIG_SHMEM */

static void smaps_pte_entry(pte_t *pte, unsigned long addr,
                struct mm_walk *walk)
{
        struct mem_size_stats *mss = walk->private;
        struct vm_area_struct *vma = walk->vma;
        bool locked = !!(vma->vm_flags & VM_LOCKED);
        struct page *page = NULL;

        if (pte_present(*pte)) {
                page = vm_normal_page(vma, addr, *pte);
        } else if (is_swap_pte(*pte)) {
                swp_entry_t swpent = pte_to_swp_entry(*pte);

                if (!non_swap_entry(swpent)) {
                        int mapcount;

                        mss->swap += PAGE_SIZE;
                        mapcount = swp_swapcount(swpent);
                        if (mapcount >= 2) {
                                u64 pss_delta = (u64)PAGE_SIZE << PSS_SHIFT;

                                do_div(pss_delta, mapcount);
                                mss->swap_pss += pss_delta;
                        } else {
                                mss->swap_pss += (u64)PAGE_SIZE << PSS_SHIFT;
                        }
                } else if (is_pfn_swap_entry(swpent))
                        page = pfn_swap_entry_to_page(swpent);
        } else if (unlikely(IS_ENABLED(CONFIG_SHMEM) && mss->check_shmem_swap
                                                        && pte_none(*pte))) {
                page = xa_load(&vma->vm_file->f_mapping->i_pages,
                                                linear_page_index(vma, addr));
                if (xa_is_value(page))
                        mss->swap += PAGE_SIZE;
                return;
        }

        if (!page)
                return;

        smaps_account(mss, page, false, pte_young(*pte), pte_dirty(*pte), locked);
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
                struct mm_walk *walk)
{
        struct mem_size_stats *mss = walk->private;
        struct vm_area_struct *vma = walk->vma;
        bool locked = !!(vma->vm_flags & VM_LOCKED);
        struct page *page = NULL;

        if (pmd_present(*pmd)) {
                /* FOLL_DUMP will return -EFAULT on huge zero page */
                page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP);
        } else if (unlikely(thp_migration_supported() && is_swap_pmd(*pmd))) {
                swp_entry_t entry = pmd_to_swp_entry(*pmd);

                if (is_migration_entry(entry))
                        page = pfn_swap_entry_to_page(entry);
        }
        if (IS_ERR_OR_NULL(page))
                return;
        if (PageAnon(page))
                mss->anonymous_thp += HPAGE_PMD_SIZE;
        else if (PageSwapBacked(page))
                mss->shmem_thp += HPAGE_PMD_SIZE;
        else if (is_zone_device_page(page))
                /* pass */;
        else
                mss->file_thp += HPAGE_PMD_SIZE;
        smaps_account(mss, page, true, pmd_young(*pmd), pmd_dirty(*pmd), locked);
}
#else
static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
                struct mm_walk *walk)
{
}
#endif

static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
                           struct mm_walk *walk)
{
        struct vm_area_struct *vma = walk->vma;
        pte_t *pte;
        spinlock_t *ptl;

        ptl = pmd_trans_huge_lock(pmd, vma);
        if (ptl) {
                smaps_pmd_entry(pmd, addr, walk);
                spin_unlock(ptl);
                goto out;
        }

        if (pmd_trans_unstable(pmd))
                goto out;
        /*
         * The mmap_lock held all the way back in m_start() is what
         * keeps khugepaged out of here and from collapsing things
         * in here.
         */
        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
        for (; addr != end; pte++, addr += PAGE_SIZE)
                smaps_pte_entry(pte, addr, walk);
        pte_unmap_unlock(pte - 1, ptl);
out:
        cond_resched();
        return 0;
}

static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
{
        /*
         * Don't forget to update Documentation/ on changes.
         */
        static const char mnemonics[BITS_PER_LONG][2] = {
                /*
                 * In case if we meet a flag we don't know about.
                 */
                [0 ... (BITS_PER_LONG-1)] = "??",

                [ilog2(VM_READ)]        = "rd",
                [ilog2(VM_WRITE)]       = "wr",
                [ilog2(VM_EXEC)]        = "ex",
                [ilog2(VM_SHARED)]      = "sh",
                [ilog2(VM_MAYREAD)]     = "mr",
                [ilog2(VM_MAYWRITE)]    = "mw",
                [ilog2(VM_MAYEXEC)]     = "me",
                [ilog2(VM_MAYSHARE)]    = "ms",
                [ilog2(VM_GROWSDOWN)]   = "gd",
                [ilog2(VM_PFNMAP)]      = "pf",
                [ilog2(VM_DENYWRITE)]   = "dw",
                [ilog2(VM_LOCKED)]      = "lo",
                [ilog2(VM_IO)]          = "io",
                [ilog2(VM_SEQ_READ)]    = "sr",
                [ilog2(VM_RAND_READ)]   = "rr",
                [ilog2(VM_DONTCOPY)]    = "dc",
                [ilog2(VM_DONTEXPAND)]  = "de",
                [ilog2(VM_ACCOUNT)]     = "ac",
                [ilog2(VM_NORESERVE)]   = "nr",
                [ilog2(VM_HUGETLB)]     = "ht",
                [ilog2(VM_SYNC)]        = "sf",
                [ilog2(VM_ARCH_1)]      = "ar",
                [ilog2(VM_WIPEONFORK)]  = "wf",
                [ilog2(VM_DONTDUMP)]    = "dd",
#ifdef CONFIG_ARM64_BTI
                [ilog2(VM_ARM64_BTI)]   = "bt",
#endif
#ifdef CONFIG_MEM_SOFT_DIRTY
                [ilog2(VM_SOFTDIRTY)]   = "sd",
#endif
                [ilog2(VM_MIXEDMAP)]    = "mm",
                [ilog2(VM_HUGEPAGE)]    = "hg",
                [ilog2(VM_NOHUGEPAGE)]  = "nh",
                [ilog2(VM_MERGEABLE)]   = "mg",
                [ilog2(VM_UFFD_MISSING)]= "um",
                [ilog2(VM_UFFD_WP)]     = "uw",
#ifdef CONFIG_ARM64_MTE
                [ilog2(VM_MTE)]         = "mt",
                [ilog2(VM_MTE_ALLOWED)] = "",
#endif
#ifdef CONFIG_ARCH_HAS_PKEYS
                /* These come out via ProtectionKey: */
                [ilog2(VM_PKEY_BIT0)]   = "",
                [ilog2(VM_PKEY_BIT1)]   = "",
                [ilog2(VM_PKEY_BIT2)]   = "",
                [ilog2(VM_PKEY_BIT3)]   = "",
#if VM_PKEY_BIT4
                [ilog2(VM_PKEY_BIT4)]   = "",
#endif
#endif /* CONFIG_ARCH_HAS_PKEYS */
#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
                [ilog2(VM_UFFD_MINOR)]  = "ui",
#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
        };
        size_t i;

        seq_puts(m, "VmFlags: ");
        for (i = 0; i < BITS_PER_LONG; i++) {
                if (!mnemonics[i][0])
                        continue;
                if (vma->vm_flags & (1UL << i)) {
                        seq_putc(m, mnemonics[i][0]);
                        seq_putc(m, mnemonics[i][1]);
                        seq_putc(m, ' ');
                }
        }
        seq_putc(m, '\n');
}

#ifdef CONFIG_HUGETLB_PAGE
static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask,
                                 unsigned long addr, unsigned long end,
                                 struct mm_walk *walk)
{
        struct mem_size_stats *mss = walk->private;
        struct vm_area_struct *vma = walk->vma;
        struct page *page = NULL;

        if (pte_present(*pte)) {
                page = vm_normal_page(vma, addr, *pte);
        } else if (is_swap_pte(*pte)) {
                swp_entry_t swpent = pte_to_swp_entry(*pte);

                if (is_pfn_swap_entry(swpent))
                        page = pfn_swap_entry_to_page(swpent);
        }
        if (page) {
                int mapcount = page_mapcount(page);

                if (mapcount >= 2)
                        mss->shared_hugetlb += huge_page_size(hstate_vma(vma));
                else
                        mss->private_hugetlb += huge_page_size(hstate_vma(vma));
        }
        return 0;
}
#else
#define smaps_hugetlb_range     NULL
#endif /* HUGETLB_PAGE */

static const struct mm_walk_ops smaps_walk_ops = {
        .pmd_entry              = smaps_pte_range,
        .hugetlb_entry          = smaps_hugetlb_range,
};

static const struct mm_walk_ops smaps_shmem_walk_ops = {
        .pmd_entry              = smaps_pte_range,
        .hugetlb_entry          = smaps_hugetlb_range,
        .pte_hole               = smaps_pte_hole,
};

/*
 * Gather mem stats from @vma with the indicated beginning
 * address @start, and keep them in @mss.
 *
 * Use vm_start of @vma as the beginning address if @start is 0.
 */
static void smap_gather_stats(struct vm_area_struct *vma,
                struct mem_size_stats *mss, unsigned long start)
{
        const struct mm_walk_ops *ops = &smaps_walk_ops;

        /* Invalid start */
        if (start >= vma->vm_end)
                return;

#ifdef CONFIG_SHMEM
        /* In case of smaps_rollup, reset the value from previous vma */
        mss->check_shmem_swap = false;
        if (vma->vm_file && shmem_mapping(vma->vm_file->f_mapping)) {
                /*
                 * For shared or readonly shmem mappings we know that all
                 * swapped out pages belong to the shmem object, and we can
                 * obtain the swap value much more efficiently. For private
                 * writable mappings, we might have COW pages that are
                 * not affected by the parent swapped out pages of the shmem
                 * object, so we have to distinguish them during the page walk.
                 * Unless we know that the shmem object (or the part mapped by
                 * our VMA) has no swapped out pages at all.
                 */
                unsigned long shmem_swapped = shmem_swap_usage(vma);

                if (!start && (!shmem_swapped || (vma->vm_flags & VM_SHARED) ||
                                        !(vma->vm_flags & VM_WRITE))) {
                        mss->swap += shmem_swapped;
                } else {
                        mss->check_shmem_swap = true;
                        ops = &smaps_shmem_walk_ops;
                }
        }
#endif
        /* mmap_lock is held in m_start */
        if (!start)
                walk_page_vma(vma, ops, mss);
        else
                walk_page_range(vma->vm_mm, start, vma->vm_end, ops, mss);
}

#define SEQ_PUT_DEC(str, val) \
                seq_put_decimal_ull_width(m, str, (val) >> 10, 8)

/* Show the contents common for smaps and smaps_rollup */
static void __show_smap(struct seq_file *m, const struct mem_size_stats *mss,
        bool rollup_mode)
{
        SEQ_PUT_DEC("Rss:            ", mss->resident);
        SEQ_PUT_DEC(" kB\nPss:            ", mss->pss >> PSS_SHIFT);
        if (rollup_mode) {
                /*
                 * These are meaningful only for smaps_rollup, otherwise two of
                 * them are zero, and the other one is the same as Pss.
                 */
                SEQ_PUT_DEC(" kB\nPss_Anon:       ",
                        mss->pss_anon >> PSS_SHIFT);
                SEQ_PUT_DEC(" kB\nPss_File:       ",
                        mss->pss_file >> PSS_SHIFT);
                SEQ_PUT_DEC(" kB\nPss_Shmem:      ",
                        mss->pss_shmem >> PSS_SHIFT);
        }
        SEQ_PUT_DEC(" kB\nShared_Clean:   ", mss->shared_clean);
        SEQ_PUT_DEC(" kB\nShared_Dirty:   ", mss->shared_dirty);
        SEQ_PUT_DEC(" kB\nPrivate_Clean:  ", mss->private_clean);
        SEQ_PUT_DEC(" kB\nPrivate_Dirty:  ", mss->private_dirty);
        SEQ_PUT_DEC(" kB\nReferenced:     ", mss->referenced);
        SEQ_PUT_DEC(" kB\nAnonymous:      ", mss->anonymous);
        SEQ_PUT_DEC(" kB\nLazyFree:       ", mss->lazyfree);
        SEQ_PUT_DEC(" kB\nAnonHugePages:  ", mss->anonymous_thp);
        SEQ_PUT_DEC(" kB\nShmemPmdMapped: ", mss->shmem_thp);
        SEQ_PUT_DEC(" kB\nFilePmdMapped:  ", mss->file_thp);
        SEQ_PUT_DEC(" kB\nShared_Hugetlb: ", mss->shared_hugetlb);
        seq_put_decimal_ull_width(m, " kB\nPrivate_Hugetlb: ",
                                  mss->private_hugetlb >> 10, 7);
        SEQ_PUT_DEC(" kB\nSwap:           ", mss->swap);
        SEQ_PUT_DEC(" kB\nSwapPss:        ",
                                        mss->swap_pss >> PSS_SHIFT);
        SEQ_PUT_DEC(" kB\nLocked:         ",
                                        mss->pss_locked >> PSS_SHIFT);
        seq_puts(m, " kB\n");
}

static int show_smap(struct seq_file *m, void *v)
{
        struct vm_area_struct *vma = v;
        struct mem_size_stats mss;

        memset(&mss, 0, sizeof(mss));

        smap_gather_stats(vma, &mss, 0);

        show_map_vma(m, vma);

        SEQ_PUT_DEC("Size:           ", vma->vm_end - vma->vm_start);
        SEQ_PUT_DEC(" kB\nKernelPageSize: ", vma_kernel_pagesize(vma));
        SEQ_PUT_DEC(" kB\nMMUPageSize:    ", vma_mmu_pagesize(vma));
        seq_puts(m, " kB\n");

        __show_smap(m, &mss, false);

        seq_printf(m, "THPeligible:    %d\n",
                   transparent_hugepage_active(vma));

        if (arch_pkeys_enabled())
                seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma));
        show_smap_vma_flags(m, vma);

        return 0;
}

static int show_smaps_rollup(struct seq_file *m, void *v)
{
        struct proc_maps_private *priv = m->private;
        struct mem_size_stats mss;
        struct mm_struct *mm;
        struct vm_area_struct *vma;
        unsigned long last_vma_end = 0;
        int ret = 0;

        priv->task = get_proc_task(priv->inode);
        if (!priv->task)
                return -ESRCH;

        mm = priv->mm;
        if (!mm || !mmget_not_zero(mm)) {
                ret = -ESRCH;
                goto out_put_task;
        }

        memset(&mss, 0, sizeof(mss));

        ret = mmap_read_lock_killable(mm);
        if (ret)
                goto out_put_mm;

        hold_task_mempolicy(priv);

        for (vma = priv->mm->mmap; vma;) {
                smap_gather_stats(vma, &mss, 0);
                last_vma_end = vma->vm_end;

                /*
                 * Release mmap_lock temporarily if someone wants to
                 * access it for write request.
                 */
                if (mmap_lock_is_contended(mm)) {
                        mmap_read_unlock(mm);
                        ret = mmap_read_lock_killable(mm);
                        if (ret) {
                                release_task_mempolicy(priv);
                                goto out_put_mm;
                        }

                        /*
                         * After dropping the lock, there are four cases to
                         * consider. See the following example for explanation.
                         *
                         *   +------+------+-----------+
                         *   | VMA1 | VMA2 | VMA3      |
                         *   +------+------+-----------+
                         *   |      |      |           |
                         *  4k     8k     16k         400k
                         *
                         * Suppose we drop the lock after reading VMA2 due to
                         * contention, then we get:
                         *
                         *      last_vma_end = 16k
                         *
                         * 1) VMA2 is freed, but VMA3 exists:
                         *
                         *    find_vma(mm, 16k - 1) will return VMA3.
                         *    In this case, just continue from VMA3.
                         *
                         * 2) VMA2 still exists:
                         *
                         *    find_vma(mm, 16k - 1) will return VMA2.
                         *    Iterate the loop like the original one.
                         *
                         * 3) No more VMAs can be found:
                         *
                         *    find_vma(mm, 16k - 1) will return NULL.
                         *    No more things to do, just break.
                         *
                         * 4) (last_vma_end - 1) is the middle of a vma (VMA'):
                         *
                         *    find_vma(mm, 16k - 1) will return VMA' whose range
                         *    contains last_vma_end.
                         *    Iterate VMA' from last_vma_end.
                         */
                        vma = find_vma(mm, last_vma_end - 1);
                        /* Case 3 above */
                        if (!vma)
                                break;

                        /* Case 1 above */
                        if (vma->vm_start >= last_vma_end)
                                continue;

                        /* Case 4 above */
                        if (vma->vm_end > last_vma_end)
                                smap_gather_stats(vma, &mss, last_vma_end);
                }
                /* Case 2 above */
                vma = vma->vm_next;
        }

        show_vma_header_prefix(m, priv->mm->mmap->vm_start,
                               last_vma_end, 0, 0, 0, 0);
        seq_pad(m, ' ');
        seq_puts(m, "[rollup]\n");

        __show_smap(m, &mss, true);

        release_task_mempolicy(priv);
        mmap_read_unlock(mm);

out_put_mm:
        mmput(mm);
out_put_task:
        put_task_struct(priv->task);
        priv->task = NULL;

        return ret;
}
#undef SEQ_PUT_DEC

static const struct seq_operations proc_pid_smaps_op = {
        .start  = m_start,
        .next   = m_next,
        .stop   = m_stop,
        .show   = show_smap
};

static int pid_smaps_open(struct inode *inode, struct file *file)
{
        return do_maps_open(inode, file, &proc_pid_smaps_op);
}

static int smaps_rollup_open(struct inode *inode, struct file *file)
{
        int ret;
        struct proc_maps_private *priv;

        priv = kzalloc(sizeof(*priv), GFP_KERNEL_ACCOUNT);
        if (!priv)
                return -ENOMEM;

        ret = single_open(file, show_smaps_rollup, priv);
        if (ret)
                goto out_free;

        priv->inode = inode;
        priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
        if (IS_ERR(priv->mm)) {
                ret = PTR_ERR(priv->mm);

                single_release(inode, file);
                goto out_free;
        }

        return 0;

out_free:
        kfree(priv);
        return ret;
}

static int smaps_rollup_release(struct inode *inode, struct file *file)
{
        struct seq_file *seq = file->private_data;
        struct proc_maps_private *priv = seq->private;

        if (priv->mm)
                mmdrop(priv->mm);

        kfree(priv);
        return single_release(inode, file);
}

const struct file_operations proc_pid_smaps_operations = {
        .open           = pid_smaps_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = proc_map_release,
};

const struct file_operations proc_pid_smaps_rollup_operations = {
        .open           = smaps_rollup_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = smaps_rollup_release,
};

enum clear_refs_types {
        CLEAR_REFS_ALL = 1,
        CLEAR_REFS_ANON,
        CLEAR_REFS_MAPPED,
        CLEAR_REFS_SOFT_DIRTY,
        CLEAR_REFS_MM_HIWATER_RSS,
        CLEAR_REFS_LAST,
};

struct clear_refs_private {
        enum clear_refs_types type;
};

#ifdef CONFIG_MEM_SOFT_DIRTY

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

        if (!pte_write(pte))
                return false;
        if (!is_cow_mapping(vma->vm_flags))
                return false;
        if (likely(!test_bit(MMF_HAS_PINNED, &vma->vm_mm->flags)))
                return false;
        page = vm_normal_page(vma, addr, pte);
        if (!page)
                return false;
        return page_maybe_dma_pinned(page);
}

static inline void clear_soft_dirty(struct vm_area_struct *vma,
                unsigned long addr, pte_t *pte)
{
        /*
         * The soft-dirty tracker uses #PF-s to catch writes
         * to pages, so write-protect the pte as well. See the
         * Documentation/admin-guide/mm/soft-dirty.rst for full description
         * of how soft-dirty works.
         */
        pte_t ptent = *pte;

        if (pte_present(ptent)) {
                pte_t old_pte;

                if (pte_is_pinned(vma, addr, ptent))
                        return;
                old_pte = ptep_modify_prot_start(vma, addr, pte);
                ptent = pte_wrprotect(old_pte);
                ptent = pte_clear_soft_dirty(ptent);
                ptep_modify_prot_commit(vma, addr, pte, old_pte, ptent);
        } else if (is_swap_pte(ptent)) {
                ptent = pte_swp_clear_soft_dirty(ptent);
                set_pte_at(vma->vm_mm, addr, pte, ptent);
        }
}
#else
static inline void clear_soft_dirty(struct vm_area_struct *vma,
                unsigned long addr, pte_t *pte)
{
}
#endif

#if defined(CONFIG_MEM_SOFT_DIRTY) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma,
                unsigned long addr, pmd_t *pmdp)
{
        pmd_t old, pmd = *pmdp;

        if (pmd_present(pmd)) {
                /* See comment in change_huge_pmd() */
                old = pmdp_invalidate(vma, addr, pmdp);
                if (pmd_dirty(old))
                        pmd = pmd_mkdirty(pmd);
                if (pmd_young(old))
                        pmd = pmd_mkyoung(pmd);

                pmd = pmd_wrprotect(pmd);
                pmd = pmd_clear_soft_dirty(pmd);

                set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
        } else if (is_migration_entry(pmd_to_swp_entry(pmd))) {
                pmd = pmd_swp_clear_soft_dirty(pmd);
                set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
        }
}
#else
static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma,
                unsigned long addr, pmd_t *pmdp)
{
}
#endif

static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
                                unsigned long end, struct mm_walk *walk)
{
        struct clear_refs_private *cp = walk->private;
        struct vm_area_struct *vma = walk->vma;
        pte_t *pte, ptent;
        spinlock_t *ptl;
        struct page *page;

        ptl = pmd_trans_huge_lock(pmd, vma);
        if (ptl) {
                if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
                        clear_soft_dirty_pmd(vma, addr, pmd);
                        goto out;
                }

                if (!pmd_present(*pmd))
                        goto out;

                page = pmd_page(*pmd);

                /* Clear accessed and referenced bits. */
                pmdp_test_and_clear_young(vma, addr, pmd);
                test_and_clear_page_young(page);
                ClearPageReferenced(page);
out:
                spin_unlock(ptl);
                return 0;
        }

        if (pmd_trans_unstable(pmd))
                return 0;

        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
        for (; addr != end; pte++, addr += PAGE_SIZE) {
                ptent = *pte;

                if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
                        clear_soft_dirty(vma, addr, pte);
                        continue;
                }

                if (!pte_present(ptent))
                        continue;

                page = vm_normal_page(vma, addr, ptent);
                if (!page)
                        continue;

                /* Clear accessed and referenced bits. */
                ptep_test_and_clear_young(vma, addr, pte);
                test_and_clear_page_young(page);
                ClearPageReferenced(page);
        }
        pte_unmap_unlock(pte - 1, ptl);
        cond_resched();
        return 0;
}

static int clear_refs_test_walk(unsigned long start, unsigned long end,
                                struct mm_walk *walk)
{
        struct clear_refs_private *cp = walk->private;
        struct vm_area_struct *vma = walk->vma;

        if (vma->vm_flags & VM_PFNMAP)
                return 1;

        /*
         * Writing 1 to /proc/pid/clear_refs affects all pages.
         * Writing 2 to /proc/pid/clear_refs only affects anonymous pages.
         * Writing 3 to /proc/pid/clear_refs only affects file mapped pages.
         * Writing 4 to /proc/pid/clear_refs affects all pages.
         */
        if (cp->type == CLEAR_REFS_ANON && vma->vm_file)
                return 1;
        if (cp->type == CLEAR_REFS_MAPPED && !vma->vm_file)
                return 1;
        return 0;
}

static const struct mm_walk_ops clear_refs_walk_ops = {
        .pmd_entry              = clear_refs_pte_range,
        .test_walk              = clear_refs_test_walk,
};

static ssize_t clear_refs_write(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        struct task_struct *task;
        char buffer[PROC_NUMBUF];
        struct mm_struct *mm;
        struct vm_area_struct *vma;
        enum clear_refs_types type;
        int itype;
        int rv;

        memset(buffer, 0, sizeof(buffer));
        if (count > sizeof(buffer) - 1)
                count = sizeof(buffer) - 1;
        if (copy_from_user(buffer, buf, count))
                return -EFAULT;
        rv = kstrtoint(strstrip(buffer), 10, &itype);
        if (rv < 0)
                return rv;
        type = (enum clear_refs_types)itype;
        if (type < CLEAR_REFS_ALL || type >= CLEAR_REFS_LAST)
                return -EINVAL;

        task = get_proc_task(file_inode(file));
        if (!task)
                return -ESRCH;
        mm = get_task_mm(task);
        if (mm) {
                struct mmu_notifier_range range;
                struct clear_refs_private cp = {
                        .type = type,
                };

                if (mmap_write_lock_killable(mm)) {
                        count = -EINTR;
                        goto out_mm;
                }
                if (type == CLEAR_REFS_MM_HIWATER_RSS) {
                        /*
                         * Writing 5 to /proc/pid/clear_refs resets the peak
                         * resident set size to this mm's current rss value.
                         */
                        reset_mm_hiwater_rss(mm);
                        goto out_unlock;
                }

                if (type == CLEAR_REFS_SOFT_DIRTY) {
                        for (vma = mm->mmap; vma; vma = vma->vm_next) {
                                if (!(vma->vm_flags & VM_SOFTDIRTY))
                                        continue;
                                vma->vm_flags &= ~VM_SOFTDIRTY;
                                vma_set_page_prot(vma);
                        }

                        inc_tlb_flush_pending(mm);
                        mmu_notifier_range_init(&range, MMU_NOTIFY_SOFT_DIRTY,
                                                0, NULL, mm, 0, -1UL);
                        mmu_notifier_invalidate_range_start(&range);
                }
                walk_page_range(mm, 0, mm->highest_vm_end, &clear_refs_walk_ops,
                                &cp);
                if (type == CLEAR_REFS_SOFT_DIRTY) {
                        mmu_notifier_invalidate_range_end(&range);
                        flush_tlb_mm(mm);
                        dec_tlb_flush_pending(mm);
                }
out_unlock:
                mmap_write_unlock(mm);
out_mm:
                mmput(mm);
        }
        put_task_struct(task);

        return count;
}

const struct file_operations proc_clear_refs_operations = {
        .write          = clear_refs_write,
        .llseek         = noop_llseek,
};

typedef struct {
        u64 pme;
} pagemap_entry_t;

struct pagemapread {
        int pos, len;           /* units: PM_ENTRY_BYTES, not bytes */
        pagemap_entry_t *buffer;
        bool show_pfn;
};

#define PAGEMAP_WALK_SIZE       (PMD_SIZE)
#define PAGEMAP_WALK_MASK       (PMD_MASK)

#define PM_ENTRY_BYTES          sizeof(pagemap_entry_t)
#define PM_PFRAME_BITS          55
#define PM_PFRAME_MASK          GENMASK_ULL(PM_PFRAME_BITS - 1, 0)
#define PM_SOFT_DIRTY           BIT_ULL(55)
#define PM_MMAP_EXCLUSIVE       BIT_ULL(56)
#define PM_UFFD_WP              BIT_ULL(57)
#define PM_FILE                 BIT_ULL(61)
#define PM_SWAP                 BIT_ULL(62)
#define PM_PRESENT              BIT_ULL(63)

#define PM_END_OF_BUFFER    1

static inline pagemap_entry_t make_pme(u64 frame, u64 flags)
{
        return (pagemap_entry_t) { .pme = (frame & PM_PFRAME_MASK) | flags };
}

static int add_to_pagemap(unsigned long addr, pagemap_entry_t *pme,
                          struct pagemapread *pm)
{
        pm->buffer[pm->pos++] = *pme;
        if (pm->pos >= pm->len)
                return PM_END_OF_BUFFER;
        return 0;
}

static int pagemap_pte_hole(unsigned long start, unsigned long end,
                            __always_unused int depth, struct mm_walk *walk)
{
        struct pagemapread *pm = walk->private;
        unsigned long addr = start;
        int err = 0;

        while (addr < end) {
                struct vm_area_struct *vma = find_vma(walk->mm, addr);
                pagemap_entry_t pme = make_pme(0, 0);
                /* End of address space hole, which we mark as non-present. */
                unsigned long hole_end;

                if (vma)
                        hole_end = min(end, vma->vm_start);
                else
                        hole_end = end;

                for (; addr < hole_end; addr += PAGE_SIZE) {
                        err = add_to_pagemap(addr, &pme, pm);
                        if (err)
                                goto out;
                }

                if (!vma)
                        break;

                /* Addresses in the VMA. */
                if (vma->vm_flags & VM_SOFTDIRTY)
                        pme = make_pme(0, PM_SOFT_DIRTY);
                for (; addr < min(end, vma->vm_end); addr += PAGE_SIZE) {
                        err = add_to_pagemap(addr, &pme, pm);
                        if (err)
                                goto out;
                }
        }
out:
        return err;
}

static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm,
                struct vm_area_struct *vma, unsigned long addr, pte_t pte)
{
        u64 frame = 0, flags = 0;
        struct page *page = NULL;

        if (pte_present(pte)) {
                if (pm->show_pfn)
                        frame = pte_pfn(pte);
                flags |= PM_PRESENT;
                page = vm_normal_page(vma, addr, pte);
                if (pte_soft_dirty(pte))
                        flags |= PM_SOFT_DIRTY;
                if (pte_uffd_wp(pte))
                        flags |= PM_UFFD_WP;
        } else if (is_swap_pte(pte)) {
                swp_entry_t entry;
                if (pte_swp_soft_dirty(pte))
                        flags |= PM_SOFT_DIRTY;
                if (pte_swp_uffd_wp(pte))
                        flags |= PM_UFFD_WP;
                entry = pte_to_swp_entry(pte);
                if (pm->show_pfn)
                        frame = swp_type(entry) |
                                (swp_offset(entry) << MAX_SWAPFILES_SHIFT);
                flags |= PM_SWAP;
                if (is_pfn_swap_entry(entry))
                        page = pfn_swap_entry_to_page(entry);
        }

        if (page && !PageAnon(page))
                flags |= PM_FILE;
        if (page && page_mapcount(page) == 1)
                flags |= PM_MMAP_EXCLUSIVE;
        if (vma->vm_flags & VM_SOFTDIRTY)
                flags |= PM_SOFT_DIRTY;

        return make_pme(frame, flags);
}

static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
                             struct mm_walk *walk)
{
        struct vm_area_struct *vma = walk->vma;
        struct pagemapread *pm = walk->private;
        spinlock_t *ptl;
        pte_t *pte, *orig_pte;
        int err = 0;

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
        ptl = pmd_trans_huge_lock(pmdp, vma);
        if (ptl) {
                u64 flags = 0, frame = 0;
                pmd_t pmd = *pmdp;
                struct page *page = NULL;

                if (vma->vm_flags & VM_SOFTDIRTY)
                        flags |= PM_SOFT_DIRTY;

                if (pmd_present(pmd)) {
                        page = pmd_page(pmd);

                        flags |= PM_PRESENT;
                        if (pmd_soft_dirty(pmd))
                                flags |= PM_SOFT_DIRTY;
                        if (pmd_uffd_wp(pmd))
                                flags |= PM_UFFD_WP;
                        if (pm->show_pfn)
                                frame = pmd_pfn(pmd) +
                                        ((addr & ~PMD_MASK) >> PAGE_SHIFT);
                }
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
                else if (is_swap_pmd(pmd)) {
                        swp_entry_t entry = pmd_to_swp_entry(pmd);
                        unsigned long offset;

                        if (pm->show_pfn) {
                                offset = swp_offset(entry) +
                                        ((addr & ~PMD_MASK) >> PAGE_SHIFT);
                                frame = swp_type(entry) |
                                        (offset << MAX_SWAPFILES_SHIFT);
                        }
                        flags |= PM_SWAP;
                        if (pmd_swp_soft_dirty(pmd))
                                flags |= PM_SOFT_DIRTY;
                        if (pmd_swp_uffd_wp(pmd))
                                flags |= PM_UFFD_WP;
                        VM_BUG_ON(!is_pmd_migration_entry(pmd));
                        page = pfn_swap_entry_to_page(entry);
                }
#endif

                if (page && page_mapcount(page) == 1)
                        flags |= PM_MMAP_EXCLUSIVE;

                for (; addr != end; addr += PAGE_SIZE) {
                        pagemap_entry_t pme = make_pme(frame, flags);

                        err = add_to_pagemap(addr, &pme, pm);
                        if (err)
                                break;
                        if (pm->show_pfn) {
                                if (flags & PM_PRESENT)
                                        frame++;
                                else if (flags & PM_SWAP)
                                        frame += (1 << MAX_SWAPFILES_SHIFT);
                        }
                }
                spin_unlock(ptl);
                return err;
        }

        if (pmd_trans_unstable(pmdp))
                return 0;
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

        /*
         * We can assume that @vma always points to a valid one and @end never
         * goes beyond vma->vm_end.
         */
        orig_pte = pte = pte_offset_map_lock(walk->mm, pmdp, addr, &ptl);
        for (; addr < end; pte++, addr += PAGE_SIZE) {
                pagemap_entry_t pme;

                pme = pte_to_pagemap_entry(pm, vma, addr, *pte);
                err = add_to_pagemap(addr, &pme, pm);
                if (err)
                        break;
        }
        pte_unmap_unlock(orig_pte, ptl);

        cond_resched();

        return err;
}

#ifdef CONFIG_HUGETLB_PAGE
/* This function walks within one hugetlb entry in the single call */
static int pagemap_hugetlb_range(pte_t *ptep, unsigned long hmask,
                                 unsigned long addr, unsigned long end,
                                 struct mm_walk *walk)
{
        struct pagemapread *pm = walk->private;
        struct vm_area_struct *vma = walk->vma;
        u64 flags = 0, frame = 0;
        int err = 0;
        pte_t pte;

        if (vma->vm_flags & VM_SOFTDIRTY)
                flags |= PM_SOFT_DIRTY;

        pte = huge_ptep_get(ptep);
        if (pte_present(pte)) {
                struct page *page = pte_page(pte);

                if (!PageAnon(page))
                        flags |= PM_FILE;

                if (page_mapcount(page) == 1)
                        flags |= PM_MMAP_EXCLUSIVE;

                flags |= PM_PRESENT;
                if (pm->show_pfn)
                        frame = pte_pfn(pte) +
                                ((addr & ~hmask) >> PAGE_SHIFT);
        }

        for (; addr != end; addr += PAGE_SIZE) {
                pagemap_entry_t pme = make_pme(frame, flags);

                err = add_to_pagemap(addr, &pme, pm);
                if (err)
                        return err;
                if (pm->show_pfn && (flags & PM_PRESENT))
                        frame++;
        }

        cond_resched();

        return err;
}
#else
#define pagemap_hugetlb_range   NULL
#endif /* HUGETLB_PAGE */

static const struct mm_walk_ops pagemap_ops = {
        .pmd_entry      = pagemap_pmd_range,
        .pte_hole       = pagemap_pte_hole,
        .hugetlb_entry  = pagemap_hugetlb_range,
};

/*
 * /proc/pid/pagemap - an array mapping virtual pages to pfns
 *
 * For each page in the address space, this file contains one 64-bit entry
 * consisting of the following:
 *
 * Bits 0-54  page frame number (PFN) if present
 * Bits 0-4   swap type if swapped
 * Bits 5-54  swap offset if swapped
 * Bit  55    pte is soft-dirty (see Documentation/admin-guide/mm/soft-dirty.rst)
 * Bit  56    page exclusively mapped
 * Bits 57-60 zero
 * Bit  61    page is file-page or shared-anon
 * Bit  62    page swapped
 * Bit  63    page present
 *
 * If the page is not present but in swap, then the PFN contains an
 * encoding of the swap file number and the page's offset into the
 * swap. Unmapped pages return a null PFN. This allows determining
 * precisely which pages are mapped (or in swap) and comparing mapped
 * pages between processes.
 *
 * Efficient users of this interface will use /proc/pid/maps to
 * determine which areas of memory are actually mapped and llseek to
 * skip over unmapped regions.
 */
static ssize_t pagemap_read(struct file *file, char __user *buf,
                            size_t count, loff_t *ppos)
{
        struct mm_struct *mm = file->private_data;
        struct pagemapread pm;
        unsigned long src;
        unsigned long svpfn;
        unsigned long start_vaddr;
        unsigned long end_vaddr;
        int ret = 0, copied = 0;

        if (!mm || !mmget_not_zero(mm))
                goto out;

        ret = -EINVAL;
        /* file position must be aligned */
        if ((*ppos % PM_ENTRY_BYTES) || (count % PM_ENTRY_BYTES))
                goto out_mm;

        ret = 0;
        if (!count)
                goto out_mm;

        /* do not disclose physical addresses: attack vector */
        pm.show_pfn = file_ns_capable(file, &init_user_ns, CAP_SYS_ADMIN);

        pm.len = (PAGEMAP_WALK_SIZE >> PAGE_SHIFT);
        pm.buffer = kmalloc_array(pm.len, PM_ENTRY_BYTES, GFP_KERNEL);
        ret = -ENOMEM;
        if (!pm.buffer)
                goto out_mm;

        src = *ppos;
        svpfn = src / PM_ENTRY_BYTES;
        end_vaddr = mm->task_size;

        /* watch out for wraparound */
        start_vaddr = end_vaddr;
        if (svpfn <= (ULONG_MAX >> PAGE_SHIFT))
                start_vaddr = untagged_addr(svpfn << PAGE_SHIFT);

        /* Ensure the address is inside the task */
        if (start_vaddr > mm->task_size)
                start_vaddr = end_vaddr;

        /*
         * The odds are that this will stop walking way
         * before end_vaddr, because the length of the
         * user buffer is tracked in "pm", and the walk
         * will stop when we hit the end of the buffer.
         */
        ret = 0;
        while (count && (start_vaddr < end_vaddr)) {
                int len;
                unsigned long end;

                pm.pos = 0;
                end = (start_vaddr + PAGEMAP_WALK_SIZE) & PAGEMAP_WALK_MASK;
                /* overflow ? */
                if (end < start_vaddr || end > end_vaddr)
                        end = end_vaddr;
                ret = mmap_read_lock_killable(mm);
                if (ret)
                        goto out_free;
                ret = walk_page_range(mm, start_vaddr, end, &pagemap_ops, &pm);
                mmap_read_unlock(mm);
                start_vaddr = end;

                len = min(count, PM_ENTRY_BYTES * pm.pos);
                if (copy_to_user(buf, pm.buffer, len)) {
                        ret = -EFAULT;
                        goto out_free;
                }
                copied += len;
                buf += len;
                count -= len;
        }
        *ppos += copied;
        if (!ret || ret == PM_END_OF_BUFFER)
                ret = copied;

out_free:
        kfree(pm.buffer);
out_mm:
        mmput(mm);
out:
        return ret;
}

static int pagemap_open(struct inode *inode, struct file *file)
{
        struct mm_struct *mm;

        mm = proc_mem_open(inode, PTRACE_MODE_READ);
        if (IS_ERR(mm))
                return PTR_ERR(mm);
        file->private_data = mm;
        return 0;
}

static int pagemap_release(struct inode *inode, struct file *file)
{
        struct mm_struct *mm = file->private_data;

        if (mm)
                mmdrop(mm);
        return 0;
}

const struct file_operations proc_pagemap_operations = {
        .llseek         = mem_lseek, /* borrow this */
        .read           = pagemap_read,
        .open           = pagemap_open,
        .release        = pagemap_release,
};
#endif /* CONFIG_PROC_PAGE_MONITOR */

#ifdef CONFIG_NUMA

struct numa_maps {
        unsigned long pages;
        unsigned long anon;
        unsigned long active;
        unsigned long writeback;
        unsigned long mapcount_max;
        unsigned long dirty;
        unsigned long swapcache;
        unsigned long node[MAX_NUMNODES];
};

struct numa_maps_private {
        struct proc_maps_private proc_maps;
        struct numa_maps md;
};

static void gather_stats(struct page *page, struct numa_maps *md, int pte_dirty,
                        unsigned long nr_pages)
{
        int count = page_mapcount(page);

        md->pages += nr_pages;
        if (pte_dirty || PageDirty(page))
                md->dirty += nr_pages;

        if (PageSwapCache(page))
                md->swapcache += nr_pages;

        if (PageActive(page) || PageUnevictable(page))
                md->active += nr_pages;

        if (PageWriteback(page))
                md->writeback += nr_pages;

        if (PageAnon(page))
                md->anon += nr_pages;

        if (count > md->mapcount_max)
                md->mapcount_max = count;

        md->node[page_to_nid(page)] += nr_pages;
}

static struct page *can_gather_numa_stats(pte_t pte, struct vm_area_struct *vma,
                unsigned long addr)
{
        struct page *page;
        int nid;

        if (!pte_present(pte))
                return NULL;

        page = vm_normal_page(vma, addr, pte);
        if (!page)
                return NULL;

        if (PageReserved(page))
                return NULL;

        nid = page_to_nid(page);
        if (!node_isset(nid, node_states[N_MEMORY]))
                return NULL;

        return page;
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static struct page *can_gather_numa_stats_pmd(pmd_t pmd,
                                              struct vm_area_struct *vma,
                                              unsigned long addr)
{
        struct page *page;
        int nid;

        if (!pmd_present(pmd))
                return NULL;

        page = vm_normal_page_pmd(vma, addr, pmd);
        if (!page)
                return NULL;

        if (PageReserved(page))
                return NULL;

        nid = page_to_nid(page);
        if (!node_isset(nid, node_states[N_MEMORY]))
                return NULL;

        return page;
}
#endif

static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
                unsigned long end, struct mm_walk *walk)
{
        struct numa_maps *md = walk->private;
        struct vm_area_struct *vma = walk->vma;
        spinlock_t *ptl;
        pte_t *orig_pte;
        pte_t *pte;

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
        ptl = pmd_trans_huge_lock(pmd, vma);
        if (ptl) {
                struct page *page;

                page = can_gather_numa_stats_pmd(*pmd, vma, addr);
                if (page)
                        gather_stats(page, md, pmd_dirty(*pmd),
                                     HPAGE_PMD_SIZE/PAGE_SIZE);
                spin_unlock(ptl);
                return 0;
        }

        if (pmd_trans_unstable(pmd))
                return 0;
#endif
        orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
        do {
                struct page *page = can_gather_numa_stats(*pte, vma, addr);
                if (!page)
                        continue;
                gather_stats(page, md, pte_dirty(*pte), 1);

        } while (pte++, addr += PAGE_SIZE, addr != end);
        pte_unmap_unlock(orig_pte, ptl);
        cond_resched();
        return 0;
}
#ifdef CONFIG_HUGETLB_PAGE
static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
                unsigned long addr, unsigned long end, struct mm_walk *walk)
{
        pte_t huge_pte = huge_ptep_get(pte);
        struct numa_maps *md;
        struct page *page;

        if (!pte_present(huge_pte))
                return 0;

        page = pte_page(huge_pte);
        if (!page)
                return 0;

        md = walk->private;
        gather_stats(page, md, pte_dirty(huge_pte), 1);
        return 0;
}

#else
static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
                unsigned long addr, unsigned long end, struct mm_walk *walk)
{
        return 0;
}
#endif

static const struct mm_walk_ops show_numa_ops = {
        .hugetlb_entry = gather_hugetlb_stats,
        .pmd_entry = gather_pte_stats,
};

/*
 * Display pages allocated per node and memory policy via /proc.
 */
static int show_numa_map(struct seq_file *m, void *v)
{
        struct numa_maps_private *numa_priv = m->private;
        struct proc_maps_private *proc_priv = &numa_priv->proc_maps;
        struct vm_area_struct *vma = v;
        struct numa_maps *md = &numa_priv->md;
        struct file *file = vma->vm_file;
        struct mm_struct *mm = vma->vm_mm;
        struct mempolicy *pol;
        char buffer[64];
        int nid;

        if (!mm)
                return 0;

        /* Ensure we start with an empty set of numa_maps statistics. */
        memset(md, 0, sizeof(*md));

        pol = __get_vma_policy(vma, vma->vm_start);
        if (pol) {
                mpol_to_str(buffer, sizeof(buffer), pol);
                mpol_cond_put(pol);
        } else {
                mpol_to_str(buffer, sizeof(buffer), proc_priv->task_mempolicy);
        }

        seq_printf(m, "%08lx %s", vma->vm_start, buffer);

        if (file) {
                seq_puts(m, " file=");
                seq_file_path(m, file, "\n\t= ");
        } else if (vma->vm_start <= mm->brk && vma->vm_end >= mm->start_brk) {
                seq_puts(m, " heap");
        } else if (is_stack(vma)) {
                seq_puts(m, " stack");
        }

        if (is_vm_hugetlb_page(vma))
                seq_puts(m, " huge");

        /* mmap_lock is held by m_start */
        walk_page_vma(vma, &show_numa_ops, md);

        if (!md->pages)
                goto out;

        if (md->anon)
                seq_printf(m, " anon=%lu", md->anon);

        if (md->dirty)
                seq_printf(m, " dirty=%lu", md->dirty);

        if (md->pages != md->anon && md->pages != md->dirty)
                seq_printf(m, " mapped=%lu", md->pages);

        if (md->mapcount_max > 1)
                seq_printf(m, " mapmax=%lu", md->mapcount_max);

        if (md->swapcache)
                seq_printf(m, " swapcache=%lu", md->swapcache);

        if (md->active < md->pages && !is_vm_hugetlb_page(vma))
                seq_printf(m, " active=%lu", md->active);

        if (md->writeback)
                seq_printf(m, " writeback=%lu", md->writeback);

        for_each_node_state(nid, N_MEMORY)
                if (md->node[nid])
                        seq_printf(m, " N%d=%lu", nid, md->node[nid]);

        seq_printf(m, " kernelpagesize_kB=%lu", vma_kernel_pagesize(vma) >> 10);
out:
        seq_putc(m, '\n');
        return 0;
}

static const struct seq_operations proc_pid_numa_maps_op = {
        .start  = m_start,
        .next   = m_next,
        .stop   = m_stop,
        .show   = show_numa_map,
};

static int pid_numa_maps_open(struct inode *inode, struct file *file)
{
        return proc_maps_open(inode, file, &proc_pid_numa_maps_op,
                                sizeof(struct numa_maps_private));
}

const struct file_operations proc_pid_numa_maps_operations = {
        .open           = pid_numa_maps_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = proc_map_release,
};

#endif /* CONFIG_NUMA */