// SPDX-License-Identifier: GPL-2.0-only
/*
 * This kernel test validates architecture page table helpers and
 * accessors and helps in verifying their continued compliance with
 * expected generic MM semantics.
 *
 * Copyright (C) 2019 ARM Ltd.
 *
 * Author: Anshuman Khandual <anshuman.khandual@arm.com>
 */
#define pr_fmt(fmt) "debug_vm_pgtable: [%-25s]: " fmt, __func__

#include <linux/gfp.h>
#include <linux/highmem.h>
#include <linux/hugetlb.h>
#include <linux/kernel.h>
#include <linux/kconfig.h>
#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/mm_types.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/pgtable.h>
#include <linux/random.h>
#include <linux/spinlock.h>
#include <linux/swap.h>
#include <linux/leafops.h>
#include <linux/start_kernel.h>
#include <linux/sched/mm.h>
#include <linux/io.h>
#include <linux/vmalloc.h>
#include <linux/pgalloc.h>

#include <asm/cacheflush.h>
#include <asm/tlbflush.h>

/*
 * Please refer Documentation/mm/arch_pgtable_helpers.rst for the semantics
 * expectations that are being validated here. All future changes in here
 * or the documentation need to be in sync.
 */
#define RANDOM_NZVALUE  GENMASK(7, 0)

struct pgtable_debug_args {
        struct mm_struct        *mm;
        struct vm_area_struct   *vma;

        pgd_t                   *pgdp;
        p4d_t                   *p4dp;
        pud_t                   *pudp;
        pmd_t                   *pmdp;
        pte_t                   *ptep;

        p4d_t                   *start_p4dp;
        pud_t                   *start_pudp;
        pmd_t                   *start_pmdp;
        pgtable_t               start_ptep;

        unsigned long           vaddr;
        pgprot_t                page_prot;
        pgprot_t                page_prot_none;

        bool                    is_contiguous_page;
        unsigned long           pud_pfn;
        unsigned long           pmd_pfn;
        unsigned long           pte_pfn;

        unsigned long           fixed_alignment;
        unsigned long           fixed_pgd_pfn;
        unsigned long           fixed_p4d_pfn;
        unsigned long           fixed_pud_pfn;
        unsigned long           fixed_pmd_pfn;
        unsigned long           fixed_pte_pfn;

        swp_entry_t             swp_entry;
        swp_entry_t             leaf_entry;
};

static void __init pte_basic_tests(struct pgtable_debug_args *args, int idx)
{
        pgprot_t prot = vm_get_page_prot(idx);
        pte_t pte = pfn_pte(args->fixed_pte_pfn, prot);
        unsigned long val = idx, *ptr = &val;

        pr_debug("Validating PTE basic (%pGv)\n", ptr);

        /*
         * This test needs to be executed after the given page table entry
         * is created with pfn_pte() to make sure that vm_get_page_prot(idx)
         * does not have the dirty bit enabled from the beginning. This is
         * important for platforms like arm64 where (!PTE_RDONLY) indicate
         * dirty bit being set.
         */
        WARN_ON(pte_dirty(pte_wrprotect(pte)));

        WARN_ON(!pte_same(pte, pte));
        WARN_ON(!pte_young(pte_mkyoung(pte_mkold(pte))));
        WARN_ON(!pte_dirty(pte_mkdirty(pte_mkclean(pte))));
        WARN_ON(!pte_write(pte_mkwrite(pte_wrprotect(pte), args->vma)));
        WARN_ON(pte_young(pte_mkold(pte_mkyoung(pte))));
        WARN_ON(pte_dirty(pte_mkclean(pte_mkdirty(pte))));
        WARN_ON(pte_write(pte_wrprotect(pte_mkwrite(pte, args->vma))));
        WARN_ON(pte_dirty(pte_wrprotect(pte_mkclean(pte))));
        WARN_ON(!pte_dirty(pte_wrprotect(pte_mkdirty(pte))));

        WARN_ON(!pte_dirty(pte_mkwrite_novma(pte_mkdirty(pte))));
        WARN_ON(pte_dirty(pte_mkwrite_novma(pte_mkclean(pte))));
        WARN_ON(!pte_write(pte_mkdirty(pte_mkwrite_novma(pte))));
        WARN_ON(!pte_write(pte_mkwrite_novma(pte_wrprotect(pte))));
        WARN_ON(pte_write(pte_wrprotect(pte_mkwrite_novma(pte))));
}

static void __init pte_advanced_tests(struct pgtable_debug_args *args)
{
        struct page *page;
        pte_t pte;

        /*
         * Architectures optimize set_pte_at by avoiding TLB flush.
         * This requires set_pte_at to be not used to update an
         * existing pte entry. Clear pte before we do set_pte_at
         *
         * flush_dcache_page() is called after set_pte_at() to clear
         * PG_arch_1 for the page on ARM64. The page flag isn't cleared
         * when it's released and page allocation check will fail when
         * the page is allocated again. For architectures other than ARM64,
         * the unexpected overhead of cache flushing is acceptable.
         */
        page = (args->pte_pfn != ULONG_MAX) ? pfn_to_page(args->pte_pfn) : NULL;
        if (!page)
                return;

        pr_debug("Validating PTE advanced\n");
        if (WARN_ON(!args->ptep))
                return;

        pte = pfn_pte(args->pte_pfn, args->page_prot);
        set_pte_at(args->mm, args->vaddr, args->ptep, pte);
        flush_dcache_page(page);
        ptep_set_wrprotect(args->mm, args->vaddr, args->ptep);
        pte = ptep_get(args->ptep);
        WARN_ON(pte_write(pte));
        ptep_get_and_clear(args->mm, args->vaddr, args->ptep);
        pte = ptep_get(args->ptep);
        WARN_ON(!pte_none(pte));

        pte = pfn_pte(args->pte_pfn, args->page_prot);
        pte = pte_wrprotect(pte);
        pte = pte_mkclean(pte);
        set_pte_at(args->mm, args->vaddr, args->ptep, pte);
        flush_dcache_page(page);
        pte = pte_mkwrite(pte, args->vma);
        pte = pte_mkdirty(pte);
        ptep_set_access_flags(args->vma, args->vaddr, args->ptep, pte, 1);
        pte = ptep_get(args->ptep);
        WARN_ON(!(pte_write(pte) && pte_dirty(pte)));
        ptep_get_and_clear_full(args->mm, args->vaddr, args->ptep, 1);
        pte = ptep_get(args->ptep);
        WARN_ON(!pte_none(pte));

        pte = pfn_pte(args->pte_pfn, args->page_prot);
        pte = pte_mkyoung(pte);
        set_pte_at(args->mm, args->vaddr, args->ptep, pte);
        flush_dcache_page(page);
        ptep_test_and_clear_young(args->vma, args->vaddr, args->ptep);
        pte = ptep_get(args->ptep);
        WARN_ON(pte_young(pte));

        ptep_get_and_clear_full(args->mm, args->vaddr, args->ptep, 1);
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx)
{
        pgprot_t prot = vm_get_page_prot(idx);
        unsigned long val = idx, *ptr = &val;
        pmd_t pmd;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD basic (%pGv)\n", ptr);
        pmd = pfn_pmd(args->fixed_pmd_pfn, prot);

        /*
         * This test needs to be executed after the given page table entry
         * is created with pfn_pmd() to make sure that vm_get_page_prot(idx)
         * does not have the dirty bit enabled from the beginning. This is
         * important for platforms like arm64 where (!PTE_RDONLY) indicate
         * dirty bit being set.
         */
        WARN_ON(pmd_dirty(pmd_wrprotect(pmd)));


        WARN_ON(!pmd_same(pmd, pmd));
        WARN_ON(!pmd_young(pmd_mkyoung(pmd_mkold(pmd))));
        WARN_ON(!pmd_dirty(pmd_mkdirty(pmd_mkclean(pmd))));
        WARN_ON(!pmd_write(pmd_mkwrite(pmd_wrprotect(pmd), args->vma)));
        WARN_ON(pmd_young(pmd_mkold(pmd_mkyoung(pmd))));
        WARN_ON(pmd_dirty(pmd_mkclean(pmd_mkdirty(pmd))));
        WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite(pmd, args->vma))));
        WARN_ON(pmd_dirty(pmd_wrprotect(pmd_mkclean(pmd))));
        WARN_ON(!pmd_dirty(pmd_wrprotect(pmd_mkdirty(pmd))));

        WARN_ON(!pmd_dirty(pmd_mkwrite_novma(pmd_mkdirty(pmd))));
        WARN_ON(pmd_dirty(pmd_mkwrite_novma(pmd_mkclean(pmd))));
        WARN_ON(!pmd_write(pmd_mkdirty(pmd_mkwrite_novma(pmd))));
        WARN_ON(!pmd_write(pmd_mkwrite_novma(pmd_wrprotect(pmd))));
        WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite_novma(pmd))));

        /*
         * A huge page does not point to next level page table
         * entry. Hence this must qualify as pmd_bad().
         */
        WARN_ON(!pmd_bad(pmd_mkhuge(pmd)));
}

static void __init pmd_advanced_tests(struct pgtable_debug_args *args)
{
        struct page *page;
        pmd_t pmd;
        unsigned long vaddr = args->vaddr;

        if (!has_transparent_hugepage())
                return;

        page = (args->pmd_pfn != ULONG_MAX) ? pfn_to_page(args->pmd_pfn) : NULL;
        if (!page)
                return;

        /*
         * flush_dcache_page() is called after set_pmd_at() to clear
         * PG_arch_1 for the page on ARM64. The page flag isn't cleared
         * when it's released and page allocation check will fail when
         * the page is allocated again. For architectures other than ARM64,
         * the unexpected overhead of cache flushing is acceptable.
         */
        pr_debug("Validating PMD advanced\n");
        /* Align the address wrt HPAGE_PMD_SIZE */
        vaddr &= HPAGE_PMD_MASK;

        pgtable_trans_huge_deposit(args->mm, args->pmdp, args->start_ptep);

        pmd = pfn_pmd(args->pmd_pfn, args->page_prot);
        set_pmd_at(args->mm, vaddr, args->pmdp, pmd);
        flush_dcache_page(page);
        pmdp_set_wrprotect(args->mm, vaddr, args->pmdp);
        pmd = pmdp_get(args->pmdp);
        WARN_ON(pmd_write(pmd));
        pmdp_huge_get_and_clear(args->mm, vaddr, args->pmdp);
        pmd = pmdp_get(args->pmdp);
        WARN_ON(!pmd_none(pmd));

        pmd = pfn_pmd(args->pmd_pfn, args->page_prot);
        pmd = pmd_wrprotect(pmd);
        pmd = pmd_mkclean(pmd);
        set_pmd_at(args->mm, vaddr, args->pmdp, pmd);
        flush_dcache_page(page);
        pmd = pmd_mkwrite(pmd, args->vma);
        pmd = pmd_mkdirty(pmd);
        pmdp_set_access_flags(args->vma, vaddr, args->pmdp, pmd, 1);
        pmd = pmdp_get(args->pmdp);
        WARN_ON(!(pmd_write(pmd) && pmd_dirty(pmd)));
        pmdp_huge_get_and_clear_full(args->vma, vaddr, args->pmdp, 1);
        pmd = pmdp_get(args->pmdp);
        WARN_ON(!pmd_none(pmd));

        pmd = pmd_mkhuge(pfn_pmd(args->pmd_pfn, args->page_prot));
        pmd = pmd_mkyoung(pmd);
        set_pmd_at(args->mm, vaddr, args->pmdp, pmd);
        flush_dcache_page(page);
        pmdp_test_and_clear_young(args->vma, vaddr, args->pmdp);
        pmd = pmdp_get(args->pmdp);
        WARN_ON(pmd_young(pmd));

        /*  Clear the pte entries  */
        pmdp_huge_get_and_clear(args->mm, vaddr, args->pmdp);
        pgtable_trans_huge_withdraw(args->mm, args->pmdp);
}

static void __init pmd_leaf_tests(struct pgtable_debug_args *args)
{
        pmd_t pmd;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD leaf\n");
        pmd = pfn_pmd(args->fixed_pmd_pfn, args->page_prot);

        /*
         * PMD based THP is a leaf entry.
         */
        pmd = pmd_mkhuge(pmd);
        WARN_ON(!pmd_leaf(pmd));
}

#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx)
{
        pgprot_t prot = vm_get_page_prot(idx);
        unsigned long val = idx, *ptr = &val;
        pud_t pud;

        if (!has_transparent_pud_hugepage())
                return;

        pr_debug("Validating PUD basic (%pGv)\n", ptr);
        pud = pfn_pud(args->fixed_pud_pfn, prot);

        /*
         * This test needs to be executed after the given page table entry
         * is created with pfn_pud() to make sure that vm_get_page_prot(idx)
         * does not have the dirty bit enabled from the beginning. This is
         * important for platforms like arm64 where (!PTE_RDONLY) indicate
         * dirty bit being set.
         */
        WARN_ON(pud_dirty(pud_wrprotect(pud)));

        WARN_ON(!pud_same(pud, pud));
        WARN_ON(!pud_young(pud_mkyoung(pud_mkold(pud))));
        WARN_ON(!pud_dirty(pud_mkdirty(pud_mkclean(pud))));
        WARN_ON(pud_dirty(pud_mkclean(pud_mkdirty(pud))));
        WARN_ON(!pud_write(pud_mkwrite(pud_wrprotect(pud))));
        WARN_ON(pud_write(pud_wrprotect(pud_mkwrite(pud))));
        WARN_ON(pud_young(pud_mkold(pud_mkyoung(pud))));
        WARN_ON(pud_dirty(pud_wrprotect(pud_mkclean(pud))));
        WARN_ON(!pud_dirty(pud_wrprotect(pud_mkdirty(pud))));

        if (mm_pmd_folded(args->mm))
                return;

        /*
         * A huge page does not point to next level page table
         * entry. Hence this must qualify as pud_bad().
         */
        WARN_ON(!pud_bad(pud_mkhuge(pud)));
}

static void __init pud_advanced_tests(struct pgtable_debug_args *args)
{
        struct page *page;
        unsigned long vaddr = args->vaddr;
        pud_t pud;

        if (!has_transparent_pud_hugepage())
                return;

        page = (args->pud_pfn != ULONG_MAX) ? pfn_to_page(args->pud_pfn) : NULL;
        if (!page)
                return;

        /*
         * flush_dcache_page() is called after set_pud_at() to clear
         * PG_arch_1 for the page on ARM64. The page flag isn't cleared
         * when it's released and page allocation check will fail when
         * the page is allocated again. For architectures other than ARM64,
         * the unexpected overhead of cache flushing is acceptable.
         */
        pr_debug("Validating PUD advanced\n");
        /* Align the address wrt HPAGE_PUD_SIZE */
        vaddr &= HPAGE_PUD_MASK;

        pud = pfn_pud(args->pud_pfn, args->page_prot);
        set_pud_at(args->mm, vaddr, args->pudp, pud);
        flush_dcache_page(page);
        pudp_set_wrprotect(args->mm, vaddr, args->pudp);
        pud = pudp_get(args->pudp);
        WARN_ON(pud_write(pud));

#ifndef __PAGETABLE_PMD_FOLDED
        pudp_huge_get_and_clear(args->mm, vaddr, args->pudp);
        pud = pudp_get(args->pudp);
        WARN_ON(!pud_none(pud));
#endif /* __PAGETABLE_PMD_FOLDED */
        pud = pfn_pud(args->pud_pfn, args->page_prot);
        pud = pud_wrprotect(pud);
        pud = pud_mkclean(pud);
        set_pud_at(args->mm, vaddr, args->pudp, pud);
        flush_dcache_page(page);
        pud = pud_mkwrite(pud);
        pud = pud_mkdirty(pud);
        pudp_set_access_flags(args->vma, vaddr, args->pudp, pud, 1);
        pud = pudp_get(args->pudp);
        WARN_ON(!(pud_write(pud) && pud_dirty(pud)));

#ifndef __PAGETABLE_PMD_FOLDED
        pudp_huge_get_and_clear_full(args->vma, vaddr, args->pudp, 1);
        pud = pudp_get(args->pudp);
        WARN_ON(!pud_none(pud));
#endif /* __PAGETABLE_PMD_FOLDED */

        pud = pfn_pud(args->pud_pfn, args->page_prot);
        pud = pud_mkyoung(pud);
        set_pud_at(args->mm, vaddr, args->pudp, pud);
        flush_dcache_page(page);
        pudp_test_and_clear_young(args->vma, vaddr, args->pudp);
        pud = pudp_get(args->pudp);
        WARN_ON(pud_young(pud));

        pudp_huge_get_and_clear(args->mm, vaddr, args->pudp);
}

static void __init pud_leaf_tests(struct pgtable_debug_args *args)
{
        pud_t pud;

        if (!has_transparent_pud_hugepage())
                return;

        pr_debug("Validating PUD leaf\n");
        pud = pfn_pud(args->fixed_pud_pfn, args->page_prot);
        /*
         * PUD based THP is a leaf entry.
         */
        pud = pud_mkhuge(pud);
        WARN_ON(!pud_leaf(pud));
}
#else  /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx) { }
static void __init pud_advanced_tests(struct pgtable_debug_args *args) { }
static void __init pud_leaf_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
#else  /* !CONFIG_TRANSPARENT_HUGEPAGE */
static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx) { }
static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx) { }
static void __init pmd_advanced_tests(struct pgtable_debug_args *args) { }
static void __init pud_advanced_tests(struct pgtable_debug_args *args) { }
static void __init pmd_leaf_tests(struct pgtable_debug_args *args) { }
static void __init pud_leaf_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
static void __init pmd_huge_tests(struct pgtable_debug_args *args)
{
        pmd_t pmd;

        if (!arch_vmap_pmd_supported(args->page_prot) ||
            args->fixed_alignment < PMD_SIZE)
                return;

        pr_debug("Validating PMD huge\n");
        /*
         * X86 defined pmd_set_huge() verifies that the given
         * PMD is not a populated non-leaf entry.
         */
        WRITE_ONCE(*args->pmdp, __pmd(0));
        WARN_ON(!pmd_set_huge(args->pmdp, __pfn_to_phys(args->fixed_pmd_pfn), args->page_prot));
        WARN_ON(!pmd_clear_huge(args->pmdp));
        pmd = pmdp_get(args->pmdp);
        WARN_ON(!pmd_none(pmd));
}

static void __init pud_huge_tests(struct pgtable_debug_args *args)
{
        pud_t pud;

        if (!arch_vmap_pud_supported(args->page_prot) ||
            args->fixed_alignment < PUD_SIZE)
                return;

        pr_debug("Validating PUD huge\n");
        /*
         * X86 defined pud_set_huge() verifies that the given
         * PUD is not a populated non-leaf entry.
         */
        WRITE_ONCE(*args->pudp, __pud(0));
        WARN_ON(!pud_set_huge(args->pudp, __pfn_to_phys(args->fixed_pud_pfn), args->page_prot));
        WARN_ON(!pud_clear_huge(args->pudp));
        pud = pudp_get(args->pudp);
        WARN_ON(!pud_none(pud));
}
#else /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
static void __init pmd_huge_tests(struct pgtable_debug_args *args) { }
static void __init pud_huge_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */

static void __init p4d_basic_tests(struct pgtable_debug_args *args)
{
        p4d_t p4d;

        pr_debug("Validating P4D basic\n");
        memset(&p4d, RANDOM_NZVALUE, sizeof(p4d_t));
        WARN_ON(!p4d_same(p4d, p4d));
}

static void __init pgd_basic_tests(struct pgtable_debug_args *args)
{
        pgd_t pgd;

        pr_debug("Validating PGD basic\n");
        memset(&pgd, RANDOM_NZVALUE, sizeof(pgd_t));
        WARN_ON(!pgd_same(pgd, pgd));
}

#ifndef __PAGETABLE_PUD_FOLDED
static void __init pud_clear_tests(struct pgtable_debug_args *args)
{
        pud_t pud = pudp_get(args->pudp);

        if (mm_pmd_folded(args->mm))
                return;

        pr_debug("Validating PUD clear\n");
        WARN_ON(pud_none(pud));
        pud_clear(args->pudp);
        pud = pudp_get(args->pudp);
        WARN_ON(!pud_none(pud));
}

static void __init pud_populate_tests(struct pgtable_debug_args *args)
{
        pud_t pud;

        if (mm_pmd_folded(args->mm))
                return;

        pr_debug("Validating PUD populate\n");
        /*
         * This entry points to next level page table page.
         * Hence this must not qualify as pud_bad().
         */
        pud_populate(args->mm, args->pudp, args->start_pmdp);
        pud = pudp_get(args->pudp);
        WARN_ON(pud_bad(pud));
}
#else  /* !__PAGETABLE_PUD_FOLDED */
static void __init pud_clear_tests(struct pgtable_debug_args *args) { }
static void __init pud_populate_tests(struct pgtable_debug_args *args) { }
#endif /* PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_P4D_FOLDED
static void __init p4d_clear_tests(struct pgtable_debug_args *args)
{
        p4d_t p4d = p4dp_get(args->p4dp);

        if (mm_pud_folded(args->mm))
                return;

        pr_debug("Validating P4D clear\n");
        WARN_ON(p4d_none(p4d));
        p4d_clear(args->p4dp);
        p4d = p4dp_get(args->p4dp);
        WARN_ON(!p4d_none(p4d));
}

static void __init p4d_populate_tests(struct pgtable_debug_args *args)
{
        p4d_t p4d;

        if (mm_pud_folded(args->mm))
                return;

        pr_debug("Validating P4D populate\n");
        /*
         * This entry points to next level page table page.
         * Hence this must not qualify as p4d_bad().
         */
        pud_clear(args->pudp);
        p4d_clear(args->p4dp);
        p4d_populate(args->mm, args->p4dp, args->start_pudp);
        p4d = p4dp_get(args->p4dp);
        WARN_ON(p4d_bad(p4d));
}

static void __init pgd_clear_tests(struct pgtable_debug_args *args)
{
        pgd_t pgd = pgdp_get(args->pgdp);

        if (mm_p4d_folded(args->mm))
                return;

        pr_debug("Validating PGD clear\n");
        WARN_ON(pgd_none(pgd));
        pgd_clear(args->pgdp);
        pgd = pgdp_get(args->pgdp);
        WARN_ON(!pgd_none(pgd));
}

static void __init pgd_populate_tests(struct pgtable_debug_args *args)
{
        pgd_t pgd;

        if (mm_p4d_folded(args->mm))
                return;

        pr_debug("Validating PGD populate\n");
        /*
         * This entry points to next level page table page.
         * Hence this must not qualify as pgd_bad().
         */
        p4d_clear(args->p4dp);
        pgd_clear(args->pgdp);
        pgd_populate(args->mm, args->pgdp, args->start_p4dp);
        pgd = pgdp_get(args->pgdp);
        WARN_ON(pgd_bad(pgd));
}
#else  /* !__PAGETABLE_P4D_FOLDED */
static void __init p4d_clear_tests(struct pgtable_debug_args *args) { }
static void __init pgd_clear_tests(struct pgtable_debug_args *args) { }
static void __init p4d_populate_tests(struct pgtable_debug_args *args) { }
static void __init pgd_populate_tests(struct pgtable_debug_args *args) { }
#endif /* PAGETABLE_P4D_FOLDED */

static void __init pte_clear_tests(struct pgtable_debug_args *args)
{
        struct page *page;
        pte_t pte = pfn_pte(args->pte_pfn, args->page_prot);

        page = (args->pte_pfn != ULONG_MAX) ? pfn_to_page(args->pte_pfn) : NULL;
        if (!page)
                return;

        /*
         * flush_dcache_page() is called after set_pte_at() to clear
         * PG_arch_1 for the page on ARM64. The page flag isn't cleared
         * when it's released and page allocation check will fail when
         * the page is allocated again. For architectures other than ARM64,
         * the unexpected overhead of cache flushing is acceptable.
         */
        pr_debug("Validating PTE clear\n");
        if (WARN_ON(!args->ptep))
                return;

        set_pte_at(args->mm, args->vaddr, args->ptep, pte);
        WARN_ON(pte_none(pte));
        flush_dcache_page(page);
        barrier();
        ptep_clear(args->mm, args->vaddr, args->ptep);
        pte = ptep_get(args->ptep);
        WARN_ON(!pte_none(pte));
}

static void __init pmd_clear_tests(struct pgtable_debug_args *args)
{
        pmd_t pmd = pmdp_get(args->pmdp);

        pr_debug("Validating PMD clear\n");
        WARN_ON(pmd_none(pmd));
        pmd_clear(args->pmdp);
        pmd = pmdp_get(args->pmdp);
        WARN_ON(!pmd_none(pmd));
}

static void __init pmd_populate_tests(struct pgtable_debug_args *args)
{
        pmd_t pmd;

        pr_debug("Validating PMD populate\n");
        /*
         * This entry points to next level page table page.
         * Hence this must not qualify as pmd_bad().
         */
        pmd_populate(args->mm, args->pmdp, args->start_ptep);
        pmd = pmdp_get(args->pmdp);
        WARN_ON(pmd_bad(pmd));
}

static void __init pte_special_tests(struct pgtable_debug_args *args)
{
        pte_t pte = pfn_pte(args->fixed_pte_pfn, args->page_prot);

        if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL))
                return;

        pr_debug("Validating PTE special\n");
        WARN_ON(!pte_special(pte_mkspecial(pte)));
}

static void __init pte_protnone_tests(struct pgtable_debug_args *args)
{
        pte_t pte = pfn_pte(args->fixed_pte_pfn, args->page_prot_none);

        if (!IS_ENABLED(CONFIG_NUMA_BALANCING))
                return;

        pr_debug("Validating PTE protnone\n");
        WARN_ON(!pte_protnone(pte));
        WARN_ON(!pte_present(pte));
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_protnone_tests(struct pgtable_debug_args *args)
{
        pmd_t pmd;

        if (!IS_ENABLED(CONFIG_NUMA_BALANCING))
                return;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD protnone\n");
        pmd = pmd_mkhuge(pfn_pmd(args->fixed_pmd_pfn, args->page_prot_none));
        WARN_ON(!pmd_protnone(pmd));
        WARN_ON(!pmd_present(pmd));
}
#else  /* !CONFIG_TRANSPARENT_HUGEPAGE */
static void __init pmd_protnone_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

static void __init pte_soft_dirty_tests(struct pgtable_debug_args *args)
{
        pte_t pte = pfn_pte(args->fixed_pte_pfn, args->page_prot);

        if (!pgtable_supports_soft_dirty())
                return;

        pr_debug("Validating PTE soft dirty\n");
        WARN_ON(!pte_soft_dirty(pte_mksoft_dirty(pte)));
        WARN_ON(pte_soft_dirty(pte_clear_soft_dirty(pte)));
}

static void __init pte_swap_soft_dirty_tests(struct pgtable_debug_args *args)
{
        pte_t pte;
        softleaf_t entry;

        if (!pgtable_supports_soft_dirty())
                return;

        pr_debug("Validating PTE swap soft dirty\n");
        pte = swp_entry_to_pte(args->swp_entry);
        entry = softleaf_from_pte(pte);

        WARN_ON(!softleaf_is_swap(entry));
        WARN_ON(!pte_swp_soft_dirty(pte_swp_mksoft_dirty(pte)));
        WARN_ON(pte_swp_soft_dirty(pte_swp_clear_soft_dirty(pte)));
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_soft_dirty_tests(struct pgtable_debug_args *args)
{
        pmd_t pmd;

        if (!pgtable_supports_soft_dirty())
                return;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD soft dirty\n");
        pmd = pfn_pmd(args->fixed_pmd_pfn, args->page_prot);
        WARN_ON(!pmd_soft_dirty(pmd_mksoft_dirty(pmd)));
        WARN_ON(pmd_soft_dirty(pmd_clear_soft_dirty(pmd)));
}

static void __init pmd_leaf_soft_dirty_tests(struct pgtable_debug_args *args)
{
        pmd_t pmd;

        if (!pgtable_supports_soft_dirty() ||
            !IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION))
                return;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD swap soft dirty\n");
        pmd = swp_entry_to_pmd(args->leaf_entry);
        WARN_ON(!pmd_is_huge(pmd));
        WARN_ON(!pmd_is_valid_softleaf(pmd));

        WARN_ON(!pmd_swp_soft_dirty(pmd_swp_mksoft_dirty(pmd)));
        WARN_ON(pmd_swp_soft_dirty(pmd_swp_clear_soft_dirty(pmd)));
}
#else  /* !CONFIG_TRANSPARENT_HUGEPAGE */
static void __init pmd_soft_dirty_tests(struct pgtable_debug_args *args) { }
static void __init pmd_leaf_soft_dirty_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

static void __init pte_swap_exclusive_tests(struct pgtable_debug_args *args)
{
        swp_entry_t entry;
        softleaf_t softleaf;
        pte_t pte;

        pr_debug("Validating PTE swap exclusive\n");
        entry = args->swp_entry;

        pte = swp_entry_to_pte(entry);
        softleaf = softleaf_from_pte(pte);

        WARN_ON(pte_swp_exclusive(pte));
        WARN_ON(!softleaf_is_swap(softleaf));
        WARN_ON(memcmp(&entry, &softleaf, sizeof(entry)));

        pte = pte_swp_mkexclusive(pte);
        softleaf = softleaf_from_pte(pte);

        WARN_ON(!pte_swp_exclusive(pte));
        WARN_ON(!softleaf_is_swap(softleaf));
        WARN_ON(pte_swp_soft_dirty(pte));
        WARN_ON(memcmp(&entry, &softleaf, sizeof(entry)));

        pte = pte_swp_clear_exclusive(pte);
        softleaf = softleaf_from_pte(pte);

        WARN_ON(pte_swp_exclusive(pte));
        WARN_ON(!softleaf_is_swap(softleaf));
        WARN_ON(memcmp(&entry, &softleaf, sizeof(entry)));
}

static void __init pte_swap_tests(struct pgtable_debug_args *args)
{
        swp_entry_t arch_entry;
        softleaf_t entry;
        pte_t pte1, pte2;

        pr_debug("Validating PTE swap\n");
        pte1 = swp_entry_to_pte(args->swp_entry);
        entry = softleaf_from_pte(pte1);

        WARN_ON(!softleaf_is_swap(entry));

        arch_entry = __pte_to_swp_entry(pte1);
        pte2 = __swp_entry_to_pte(arch_entry);
        WARN_ON(memcmp(&pte1, &pte2, sizeof(pte1)));
}

#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
static void __init pmd_softleaf_tests(struct pgtable_debug_args *args)
{
        swp_entry_t arch_entry;
        pmd_t pmd1, pmd2;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD swap\n");
        pmd1 = swp_entry_to_pmd(args->leaf_entry);
        WARN_ON(!pmd_is_huge(pmd1));
        WARN_ON(!pmd_is_valid_softleaf(pmd1));

        arch_entry = __pmd_to_swp_entry(pmd1);
        pmd2 = __swp_entry_to_pmd(arch_entry);
        WARN_ON(memcmp(&pmd1, &pmd2, sizeof(pmd1)));
}
#else  /* !CONFIG_ARCH_ENABLE_THP_MIGRATION */
static void __init pmd_softleaf_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_ARCH_ENABLE_THP_MIGRATION */

static void __init swap_migration_tests(struct pgtable_debug_args *args)
{
        struct page *page;
        softleaf_t entry;

        if (!IS_ENABLED(CONFIG_MIGRATION))
                return;

        /*
         * swap_migration_tests() requires a dedicated page as it needs to
         * be locked before creating a migration entry from it. Locking the
         * page that actually maps kernel text ('start_kernel') can be real
         * problematic. Lets use the allocated page explicitly for this
         * purpose.
         */
        page = (args->pte_pfn != ULONG_MAX) ? pfn_to_page(args->pte_pfn) : NULL;
        if (!page)
                return;

        pr_debug("Validating swap migration\n");

        /*
         * make_[readable|writable]_migration_entry() expects given page to
         * be locked, otherwise it stumbles upon a BUG_ON().
         */
        __SetPageLocked(page);
        entry = make_writable_migration_entry(page_to_pfn(page));
        WARN_ON(!softleaf_is_migration(entry));
        WARN_ON(!softleaf_is_migration_write(entry));

        entry = make_readable_migration_entry(swp_offset(entry));
        WARN_ON(!softleaf_is_migration(entry));
        WARN_ON(softleaf_is_migration_write(entry));

        entry = make_readable_migration_entry(page_to_pfn(page));
        WARN_ON(!softleaf_is_migration(entry));
        WARN_ON(softleaf_is_migration_write(entry));
        __ClearPageLocked(page);
}

#ifdef CONFIG_HUGETLB_PAGE
static void __init hugetlb_basic_tests(struct pgtable_debug_args *args)
{
        pte_t pte;

        pr_debug("Validating HugeTLB basic\n");
        pte = pfn_pte(args->fixed_pmd_pfn, args->page_prot);
        pte = arch_make_huge_pte(pte, PMD_SHIFT, VM_ACCESS_FLAGS);

#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
        WARN_ON(!pte_huge(pte));
#endif
        WARN_ON(!huge_pte_dirty(huge_pte_mkdirty(pte)));
        WARN_ON(!huge_pte_write(huge_pte_mkwrite(huge_pte_wrprotect(pte))));
        WARN_ON(huge_pte_write(huge_pte_wrprotect(huge_pte_mkwrite(pte))));
}
#else  /* !CONFIG_HUGETLB_PAGE */
static void __init hugetlb_basic_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_HUGETLB_PAGE */

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_thp_tests(struct pgtable_debug_args *args)
{
        pmd_t pmd;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD based THP\n");
        /*
         * pmd_trans_huge() and pmd_present() must return positive after
         * MMU invalidation with pmd_mkinvalid(). This behavior is an
         * optimization for transparent huge page. pmd_trans_huge() must
         * be true if pmd_page() returns a valid THP to avoid taking the
         * pmd_lock when others walk over non transhuge pmds (i.e. there
         * are no THP allocated). Especially when splitting a THP and
         * removing the present bit from the pmd, pmd_trans_huge() still
         * needs to return true. pmd_present() should be true whenever
         * pmd_trans_huge() returns true.
         */
        pmd = pfn_pmd(args->fixed_pmd_pfn, args->page_prot);
        WARN_ON(!pmd_trans_huge(pmd_mkhuge(pmd)));

#ifndef __HAVE_ARCH_PMDP_INVALIDATE
        WARN_ON(!pmd_trans_huge(pmd_mkinvalid(pmd_mkhuge(pmd))));
        WARN_ON(!pmd_present(pmd_mkinvalid(pmd_mkhuge(pmd))));
        WARN_ON(!pmd_leaf(pmd_mkinvalid(pmd_mkhuge(pmd))));
#endif /* __HAVE_ARCH_PMDP_INVALIDATE */
}

#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static void __init pud_thp_tests(struct pgtable_debug_args *args)
{
        pud_t pud;

        if (!has_transparent_pud_hugepage())
                return;

        pr_debug("Validating PUD based THP\n");
        pud = pfn_pud(args->fixed_pud_pfn, args->page_prot);
        WARN_ON(!pud_trans_huge(pud_mkhuge(pud)));

        /*
         * pud_mkinvalid() has been dropped for now. Enable back
         * these tests when it comes back with a modified pud_present().
         *
         * WARN_ON(!pud_trans_huge(pud_mkinvalid(pud_mkhuge(pud))));
         * WARN_ON(!pud_present(pud_mkinvalid(pud_mkhuge(pud))));
         */
}
#else  /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
static void __init pud_thp_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
#else  /* !CONFIG_TRANSPARENT_HUGEPAGE */
static void __init pmd_thp_tests(struct pgtable_debug_args *args) { }
static void __init pud_thp_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

static unsigned long __init get_random_vaddr(void)
{
        unsigned long random_vaddr, random_pages, total_user_pages;

        total_user_pages = (TASK_SIZE - FIRST_USER_ADDRESS) / PAGE_SIZE;

        random_pages = get_random_long() % total_user_pages;
        random_vaddr = FIRST_USER_ADDRESS + random_pages * PAGE_SIZE;

        return random_vaddr;
}

static void __init
debug_vm_pgtable_free_huge_page(struct pgtable_debug_args *args,
                unsigned long pfn, int order)
{
#ifdef CONFIG_CONTIG_ALLOC
        if (args->is_contiguous_page) {
                free_contig_range(pfn, 1 << order);
                return;
        }
#endif
        __free_pages(pfn_to_page(pfn), order);
}

static void __init destroy_args(struct pgtable_debug_args *args)
{
        /* Free (huge) page */
        if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
            has_transparent_pud_hugepage() &&
            args->pud_pfn != ULONG_MAX) {
                debug_vm_pgtable_free_huge_page(args, args->pud_pfn, HPAGE_PUD_ORDER);
                args->pud_pfn = ULONG_MAX;
                args->pmd_pfn = ULONG_MAX;
                args->pte_pfn = ULONG_MAX;
        }

        if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
            has_transparent_hugepage() &&
            args->pmd_pfn != ULONG_MAX) {
                debug_vm_pgtable_free_huge_page(args, args->pmd_pfn, HPAGE_PMD_ORDER);
                args->pmd_pfn = ULONG_MAX;
                args->pte_pfn = ULONG_MAX;
        }

        if (args->pte_pfn != ULONG_MAX) {
                __free_page(pfn_to_page(args->pte_pfn));

                args->pte_pfn = ULONG_MAX;
        }

        /* Free page table entries */
        if (args->start_ptep) {
                pmd_clear(args->pmdp);
                pte_free(args->mm, args->start_ptep);
                mm_dec_nr_ptes(args->mm);
        }

        if (args->start_pmdp) {
                pud_clear(args->pudp);
                pmd_free(args->mm, args->start_pmdp);
                mm_dec_nr_pmds(args->mm);
        }

        if (args->start_pudp) {
                p4d_clear(args->p4dp);
                pud_free(args->mm, args->start_pudp);
                mm_dec_nr_puds(args->mm);
        }

        if (args->start_p4dp) {
                pgd_clear(args->pgdp);
                p4d_free(args->mm, args->start_p4dp);
        }

        /* Free vma and mm struct */
        if (args->vma)
                vm_area_free(args->vma);

        if (args->mm)
                mmput(args->mm);
}

static struct page * __init
debug_vm_pgtable_alloc_huge_page(struct pgtable_debug_args *args, int order)
{
        struct page *page = NULL;

#ifdef CONFIG_CONTIG_ALLOC
        if (order > MAX_PAGE_ORDER) {
                page = alloc_contig_pages((1 << order), GFP_KERNEL,
                                          first_online_node, NULL);
                if (page) {
                        args->is_contiguous_page = true;
                        return page;
                }
        }
#endif

        if (order <= MAX_PAGE_ORDER)
                page = alloc_pages(GFP_KERNEL, order);

        return page;
}

/*
 * Check if a physical memory range described by <pstart, pend> contains
 * an area that is of size psize, and aligned to psize.
 *
 * Don't use address 0, an all-zeroes physical address might mask bugs, and
 * it's not used on x86.
 */
static void  __init phys_align_check(phys_addr_t pstart,
                                     phys_addr_t pend, unsigned long psize,
                                     phys_addr_t *physp, unsigned long *alignp)
{
        phys_addr_t aligned_start, aligned_end;

        if (pstart == 0)
                pstart = PAGE_SIZE;

        aligned_start = ALIGN(pstart, psize);
        aligned_end = aligned_start + psize;

        if (aligned_end > aligned_start && aligned_end <= pend) {
                *alignp = psize;
                *physp = aligned_start;
        }
}

static void __init init_fixed_pfns(struct pgtable_debug_args *args)
{
        u64 idx;
        phys_addr_t phys, pstart, pend;

        /*
         * Initialize the fixed pfns. To do this, try to find a
         * valid physical range, preferably aligned to PUD_SIZE,
         * but settling for aligned to PMD_SIZE as a fallback. If
         * neither of those is found, use the physical address of
         * the start_kernel symbol.
         *
         * The memory doesn't need to be allocated, it just needs to exist
         * as usable memory. It won't be touched.
         *
         * The alignment is recorded, and can be checked to see if we
         * can run the tests that require an actual valid physical
         * address range on some architectures ({pmd,pud}_huge_test
         * on x86).
         */

        phys = __pa_symbol(&start_kernel);
        args->fixed_alignment = PAGE_SIZE;

        for_each_mem_range(idx, &pstart, &pend) {
                /* First check for a PUD-aligned area */
                phys_align_check(pstart, pend, PUD_SIZE, &phys,
                                 &args->fixed_alignment);

                /* If a PUD-aligned area is found, we're done */
                if (args->fixed_alignment == PUD_SIZE)
                        break;

                /*
                 * If no PMD-aligned area found yet, check for one,
                 * but continue the loop to look for a PUD-aligned area.
                 */
                if (args->fixed_alignment < PMD_SIZE)
                        phys_align_check(pstart, pend, PMD_SIZE, &phys,
                                         &args->fixed_alignment);
        }

        args->fixed_pgd_pfn = __phys_to_pfn(phys & PGDIR_MASK);
        args->fixed_p4d_pfn = __phys_to_pfn(phys & P4D_MASK);
        args->fixed_pud_pfn = __phys_to_pfn(phys & PUD_MASK);
        args->fixed_pmd_pfn = __phys_to_pfn(phys & PMD_MASK);
        args->fixed_pte_pfn = __phys_to_pfn(phys & PAGE_MASK);
        WARN_ON(!pfn_valid(args->fixed_pte_pfn));
}


static int __init init_args(struct pgtable_debug_args *args)
{
        unsigned long max_swap_offset;
        struct page *page = NULL;
        int ret = 0;

        /*
         * Initialize the debugging data.
         *
         * vm_get_page_prot(VM_NONE) or vm_get_page_prot(VM_SHARED|VM_NONE)
         * will help create page table entries with PROT_NONE permission as
         * required for pxx_protnone_tests().
         */
        memset(args, 0, sizeof(*args));
        args->vaddr              = get_random_vaddr();
        args->page_prot          = vm_get_page_prot(VM_ACCESS_FLAGS);
        args->page_prot_none     = vm_get_page_prot(VM_NONE);
        args->is_contiguous_page = false;
        args->pud_pfn            = ULONG_MAX;
        args->pmd_pfn            = ULONG_MAX;
        args->pte_pfn            = ULONG_MAX;
        args->fixed_pgd_pfn      = ULONG_MAX;
        args->fixed_p4d_pfn      = ULONG_MAX;
        args->fixed_pud_pfn      = ULONG_MAX;
        args->fixed_pmd_pfn      = ULONG_MAX;
        args->fixed_pte_pfn      = ULONG_MAX;

        /* Allocate mm and vma */
        args->mm = mm_alloc();
        if (!args->mm) {
                pr_err("Failed to allocate mm struct\n");
                ret = -ENOMEM;
                goto error;
        }

        args->vma = vm_area_alloc(args->mm);
        if (!args->vma) {
                pr_err("Failed to allocate vma\n");
                ret = -ENOMEM;
                goto error;
        }

        /*
         * Allocate page table entries. They will be modified in the tests.
         * Lets save the page table entries so that they can be released
         * when the tests are completed.
         */
        args->pgdp = pgd_offset(args->mm, args->vaddr);
        args->p4dp = p4d_alloc(args->mm, args->pgdp, args->vaddr);
        if (!args->p4dp) {
                pr_err("Failed to allocate p4d entries\n");
                ret = -ENOMEM;
                goto error;
        }
        args->start_p4dp = p4d_offset(args->pgdp, 0UL);
        WARN_ON(!args->start_p4dp);

        args->pudp = pud_alloc(args->mm, args->p4dp, args->vaddr);
        if (!args->pudp) {
                pr_err("Failed to allocate pud entries\n");
                ret = -ENOMEM;
                goto error;
        }
        args->start_pudp = pud_offset(args->p4dp, 0UL);
        WARN_ON(!args->start_pudp);

        args->pmdp = pmd_alloc(args->mm, args->pudp, args->vaddr);
        if (!args->pmdp) {
                pr_err("Failed to allocate pmd entries\n");
                ret = -ENOMEM;
                goto error;
        }
        args->start_pmdp = pmd_offset(args->pudp, 0UL);
        WARN_ON(!args->start_pmdp);

        if (pte_alloc(args->mm, args->pmdp)) {
                pr_err("Failed to allocate pte entries\n");
                ret = -ENOMEM;
                goto error;
        }
        args->start_ptep = pmd_pgtable(pmdp_get(args->pmdp));
        WARN_ON(!args->start_ptep);

        init_fixed_pfns(args);

        /* See generic_max_swapfile_size(): probe the maximum offset */
        max_swap_offset = swp_offset(softleaf_from_pte(softleaf_to_pte(swp_entry(0, ~0UL))));
        /* Create a swp entry with all possible bits set while still being swap. */
        args->swp_entry = swp_entry(MAX_SWAPFILES - 1, max_swap_offset);
        /* Create a non-present migration entry. */
        args->leaf_entry = make_writable_migration_entry(~0UL);

        /*
         * Allocate (huge) pages because some of the tests need to access
         * the data in the pages. The corresponding tests will be skipped
         * if we fail to allocate (huge) pages.
         */
        if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
            has_transparent_pud_hugepage()) {
                page = debug_vm_pgtable_alloc_huge_page(args, HPAGE_PUD_ORDER);
                if (page) {
                        args->pud_pfn = page_to_pfn(page);
                        args->pmd_pfn = args->pud_pfn;
                        args->pte_pfn = args->pud_pfn;
                        return 0;
                }
        }

        if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
            has_transparent_hugepage()) {
                page = debug_vm_pgtable_alloc_huge_page(args, HPAGE_PMD_ORDER);
                if (page) {
                        args->pmd_pfn = page_to_pfn(page);
                        args->pte_pfn = args->pmd_pfn;
                        return 0;
                }
        }

        page = alloc_page(GFP_KERNEL);
        if (page)
                args->pte_pfn = page_to_pfn(page);

        return 0;

error:
        destroy_args(args);
        return ret;
}

static int __init debug_vm_pgtable(void)
{
        struct pgtable_debug_args args;
        spinlock_t *ptl = NULL;
        int idx, ret;

        pr_info("Validating architecture page table helpers\n");
        ret = init_args(&args);
        if (ret)
                return ret;

        /*
         * Iterate over each possible vm_flags to make sure that all
         * the basic page table transformation validations just hold
         * true irrespective of the starting protection value for a
         * given page table entry.
         *
         * Protection based vm_flags combinations are always linear
         * and increasing i.e starting from VM_NONE and going up to
         * (VM_SHARED | READ | WRITE | EXEC).
         */
#define VM_FLAGS_START  (VM_NONE)
#define VM_FLAGS_END    (VM_SHARED | VM_EXEC | VM_WRITE | VM_READ)

        for (idx = VM_FLAGS_START; idx <= VM_FLAGS_END; idx++) {
                pte_basic_tests(&args, idx);
                pmd_basic_tests(&args, idx);
                pud_basic_tests(&args, idx);
        }

        /*
         * Both P4D and PGD level tests are very basic which do not
         * involve creating page table entries from the protection
         * value and the given pfn. Hence just keep them out from
         * the above iteration for now to save some test execution
         * time.
         */
        p4d_basic_tests(&args);
        pgd_basic_tests(&args);

        pmd_leaf_tests(&args);
        pud_leaf_tests(&args);

        pte_special_tests(&args);
        pte_protnone_tests(&args);
        pmd_protnone_tests(&args);

        pte_soft_dirty_tests(&args);
        pmd_soft_dirty_tests(&args);
        pte_swap_soft_dirty_tests(&args);
        pmd_leaf_soft_dirty_tests(&args);

        pte_swap_exclusive_tests(&args);

        pte_swap_tests(&args);
        pmd_softleaf_tests(&args);

        swap_migration_tests(&args);

        pmd_thp_tests(&args);
        pud_thp_tests(&args);

        hugetlb_basic_tests(&args);

        /*
         * Page table modifying tests. They need to hold
         * proper page table lock.
         */

        args.ptep = pte_offset_map_lock(args.mm, args.pmdp, args.vaddr, &ptl);
        pte_clear_tests(&args);
        pte_advanced_tests(&args);
        if (args.ptep)
                pte_unmap_unlock(args.ptep, ptl);

        ptl = pmd_lock(args.mm, args.pmdp);
        pmd_clear_tests(&args);
        pmd_advanced_tests(&args);
        pmd_huge_tests(&args);
        pmd_populate_tests(&args);
        spin_unlock(ptl);

        ptl = pud_lock(args.mm, args.pudp);
        pud_clear_tests(&args);
        pud_advanced_tests(&args);
        pud_huge_tests(&args);
        pud_populate_tests(&args);
        spin_unlock(ptl);

        spin_lock(&(args.mm->page_table_lock));
        p4d_clear_tests(&args);
        pgd_clear_tests(&args);
        p4d_populate_tests(&args);
        pgd_populate_tests(&args);
        spin_unlock(&(args.mm->page_table_lock));

        destroy_args(&args);
        return 0;
}
late_initcall(debug_vm_pgtable);