// 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/mm.h>
#include <linux/mman.h>
#include <linux/mm_types.h>
#include <linux/module.h>
#include <linux/pfn_t.h>
#include <linux/printk.h>
#include <linux/pgtable.h>
#include <linux/random.h>
#include <linux/spinlock.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/start_kernel.h>
#include <linux/sched/mm.h>
#include <linux/io.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>

/*
 * Please refer Documentation/vm/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 VMFLAGS (VM_READ|VM_WRITE|VM_EXEC)

/*
 * On s390 platform, the lower 4 bits are used to identify given page table
 * entry type. But these bits might affect the ability to clear entries with
 * pxx_clear() because of how dynamic page table folding works on s390. So
 * while loading up the entries do not change the lower 4 bits. It does not
 * have affect any other platform. Also avoid the 62nd bit on ppc64 that is
 * used to mark a pte entry.
 */
#define S390_SKIP_MASK          GENMASK(3, 0)
#if __BITS_PER_LONG == 64
#define PPC64_SKIP_MASK         GENMASK(62, 62)
#else
#define PPC64_SKIP_MASK         0x0
#endif
#define ARCH_SKIP_MASK (S390_SKIP_MASK | PPC64_SKIP_MASK)
#define RANDOM_ORVALUE (GENMASK(BITS_PER_LONG - 1, 0) & ~ARCH_SKIP_MASK)
#define RANDOM_NZVALUE  GENMASK(7, 0)

static void __init pte_basic_tests(unsigned long pfn, int idx)
{
        pgprot_t prot = protection_map[idx];
        pte_t pte = pfn_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 protection_map[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))));
        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))));
        WARN_ON(pte_dirty(pte_wrprotect(pte_mkclean(pte))));
        WARN_ON(!pte_dirty(pte_wrprotect(pte_mkdirty(pte))));
}

static void __init pte_advanced_tests(struct mm_struct *mm,
                                      struct vm_area_struct *vma, pte_t *ptep,
                                      unsigned long pfn, unsigned long vaddr,
                                      pgprot_t prot)
{
        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
         */

        pr_debug("Validating PTE advanced\n");
        pte = pfn_pte(pfn, prot);
        set_pte_at(mm, vaddr, ptep, pte);
        ptep_set_wrprotect(mm, vaddr, ptep);
        pte = ptep_get(ptep);
        WARN_ON(pte_write(pte));
        ptep_get_and_clear(mm, vaddr, ptep);
        pte = ptep_get(ptep);
        WARN_ON(!pte_none(pte));

        pte = pfn_pte(pfn, prot);
        pte = pte_wrprotect(pte);
        pte = pte_mkclean(pte);
        set_pte_at(mm, vaddr, ptep, pte);
        pte = pte_mkwrite(pte);
        pte = pte_mkdirty(pte);
        ptep_set_access_flags(vma, vaddr, ptep, pte, 1);
        pte = ptep_get(ptep);
        WARN_ON(!(pte_write(pte) && pte_dirty(pte)));
        ptep_get_and_clear_full(mm, vaddr, ptep, 1);
        pte = ptep_get(ptep);
        WARN_ON(!pte_none(pte));

        pte = pfn_pte(pfn, prot);
        pte = pte_mkyoung(pte);
        set_pte_at(mm, vaddr, ptep, pte);
        ptep_test_and_clear_young(vma, vaddr, ptep);
        pte = ptep_get(ptep);
        WARN_ON(pte_young(pte));
}

static void __init pte_savedwrite_tests(unsigned long pfn, pgprot_t prot)
{
        pte_t pte = pfn_pte(pfn, prot);

        if (!IS_ENABLED(CONFIG_NUMA_BALANCING))
                return;

        pr_debug("Validating PTE saved write\n");
        WARN_ON(!pte_savedwrite(pte_mk_savedwrite(pte_clear_savedwrite(pte))));
        WARN_ON(pte_savedwrite(pte_clear_savedwrite(pte_mk_savedwrite(pte))));
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_basic_tests(unsigned long pfn, int idx)
{
        pgprot_t prot = protection_map[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(pfn, prot);

        /*
         * This test needs to be executed after the given page table entry
         * is created with pfn_pmd() to make sure that protection_map[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))));
        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))));
        WARN_ON(pmd_dirty(pmd_wrprotect(pmd_mkclean(pmd))));
        WARN_ON(!pmd_dirty(pmd_wrprotect(pmd_mkdirty(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 mm_struct *mm,
                                      struct vm_area_struct *vma, pmd_t *pmdp,
                                      unsigned long pfn, unsigned long vaddr,
                                      pgprot_t prot, pgtable_t pgtable)
{
        pmd_t pmd;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD advanced\n");
        /* Align the address wrt HPAGE_PMD_SIZE */
        vaddr &= HPAGE_PMD_MASK;

        pgtable_trans_huge_deposit(mm, pmdp, pgtable);

        pmd = pfn_pmd(pfn, prot);
        set_pmd_at(mm, vaddr, pmdp, pmd);
        pmdp_set_wrprotect(mm, vaddr, pmdp);
        pmd = READ_ONCE(*pmdp);
        WARN_ON(pmd_write(pmd));
        pmdp_huge_get_and_clear(mm, vaddr, pmdp);
        pmd = READ_ONCE(*pmdp);
        WARN_ON(!pmd_none(pmd));

        pmd = pfn_pmd(pfn, prot);
        pmd = pmd_wrprotect(pmd);
        pmd = pmd_mkclean(pmd);
        set_pmd_at(mm, vaddr, pmdp, pmd);
        pmd = pmd_mkwrite(pmd);
        pmd = pmd_mkdirty(pmd);
        pmdp_set_access_flags(vma, vaddr, pmdp, pmd, 1);
        pmd = READ_ONCE(*pmdp);
        WARN_ON(!(pmd_write(pmd) && pmd_dirty(pmd)));
        pmdp_huge_get_and_clear_full(vma, vaddr, pmdp, 1);
        pmd = READ_ONCE(*pmdp);
        WARN_ON(!pmd_none(pmd));

        pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
        pmd = pmd_mkyoung(pmd);
        set_pmd_at(mm, vaddr, pmdp, pmd);
        pmdp_test_and_clear_young(vma, vaddr, pmdp);
        pmd = READ_ONCE(*pmdp);
        WARN_ON(pmd_young(pmd));

        /*  Clear the pte entries  */
        pmdp_huge_get_and_clear(mm, vaddr, pmdp);
        pgtable = pgtable_trans_huge_withdraw(mm, pmdp);
}

static void __init pmd_leaf_tests(unsigned long pfn, pgprot_t prot)
{
        pmd_t pmd;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD leaf\n");
        pmd = pfn_pmd(pfn, prot);

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

static void __init pmd_savedwrite_tests(unsigned long pfn, pgprot_t prot)
{
        pmd_t pmd;

        if (!IS_ENABLED(CONFIG_NUMA_BALANCING))
                return;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD saved write\n");
        pmd = pfn_pmd(pfn, prot);
        WARN_ON(!pmd_savedwrite(pmd_mk_savedwrite(pmd_clear_savedwrite(pmd))));
        WARN_ON(pmd_savedwrite(pmd_clear_savedwrite(pmd_mk_savedwrite(pmd))));
}

#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static void __init pud_basic_tests(struct mm_struct *mm, unsigned long pfn, int idx)
{
        pgprot_t prot = protection_map[idx];
        unsigned long val = idx, *ptr = &val;
        pud_t pud;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PUD basic (%pGv)\n", ptr);
        pud = pfn_pud(pfn, prot);

        /*
         * This test needs to be executed after the given page table entry
         * is created with pfn_pud() to make sure that protection_map[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(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 mm_struct *mm,
                                      struct vm_area_struct *vma, pud_t *pudp,
                                      unsigned long pfn, unsigned long vaddr,
                                      pgprot_t prot)
{
        pud_t pud;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PUD advanced\n");
        /* Align the address wrt HPAGE_PUD_SIZE */
        vaddr &= HPAGE_PUD_MASK;

        pud = pfn_pud(pfn, prot);
        set_pud_at(mm, vaddr, pudp, pud);
        pudp_set_wrprotect(mm, vaddr, pudp);
        pud = READ_ONCE(*pudp);
        WARN_ON(pud_write(pud));

#ifndef __PAGETABLE_PMD_FOLDED
        pudp_huge_get_and_clear(mm, vaddr, pudp);
        pud = READ_ONCE(*pudp);
        WARN_ON(!pud_none(pud));
#endif /* __PAGETABLE_PMD_FOLDED */
        pud = pfn_pud(pfn, prot);
        pud = pud_wrprotect(pud);
        pud = pud_mkclean(pud);
        set_pud_at(mm, vaddr, pudp, pud);
        pud = pud_mkwrite(pud);
        pud = pud_mkdirty(pud);
        pudp_set_access_flags(vma, vaddr, pudp, pud, 1);
        pud = READ_ONCE(*pudp);
        WARN_ON(!(pud_write(pud) && pud_dirty(pud)));

#ifndef __PAGETABLE_PMD_FOLDED
        pudp_huge_get_and_clear_full(mm, vaddr, pudp, 1);
        pud = READ_ONCE(*pudp);
        WARN_ON(!pud_none(pud));
#endif /* __PAGETABLE_PMD_FOLDED */

        pud = pfn_pud(pfn, prot);
        pud = pud_mkyoung(pud);
        set_pud_at(mm, vaddr, pudp, pud);
        pudp_test_and_clear_young(vma, vaddr, pudp);
        pud = READ_ONCE(*pudp);
        WARN_ON(pud_young(pud));

        pudp_huge_get_and_clear(mm, vaddr, pudp);
}

static void __init pud_leaf_tests(unsigned long pfn, pgprot_t prot)
{
        pud_t pud;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PUD leaf\n");
        pud = pfn_pud(pfn, 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 mm_struct *mm, unsigned long pfn, int idx) { }
static void __init pud_advanced_tests(struct mm_struct *mm,
                                      struct vm_area_struct *vma, pud_t *pudp,
                                      unsigned long pfn, unsigned long vaddr,
                                      pgprot_t prot)
{
}
static void __init pud_leaf_tests(unsigned long pfn, pgprot_t prot) { }
#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
#else  /* !CONFIG_TRANSPARENT_HUGEPAGE */
static void __init pmd_basic_tests(unsigned long pfn, int idx) { }
static void __init pud_basic_tests(struct mm_struct *mm, unsigned long pfn, int idx) { }
static void __init pmd_advanced_tests(struct mm_struct *mm,
                                      struct vm_area_struct *vma, pmd_t *pmdp,
                                      unsigned long pfn, unsigned long vaddr,
                                      pgprot_t prot, pgtable_t pgtable)
{
}
static void __init pud_advanced_tests(struct mm_struct *mm,
                                      struct vm_area_struct *vma, pud_t *pudp,
                                      unsigned long pfn, unsigned long vaddr,
                                      pgprot_t prot)
{
}
static void __init pmd_leaf_tests(unsigned long pfn, pgprot_t prot) { }
static void __init pud_leaf_tests(unsigned long pfn, pgprot_t prot) { }
static void __init pmd_savedwrite_tests(unsigned long pfn, pgprot_t prot) { }
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot)
{
        pmd_t pmd;

        if (!arch_vmap_pmd_supported(prot))
                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(*pmdp, __pmd(0));
        WARN_ON(!pmd_set_huge(pmdp, __pfn_to_phys(pfn), prot));
        WARN_ON(!pmd_clear_huge(pmdp));
        pmd = READ_ONCE(*pmdp);
        WARN_ON(!pmd_none(pmd));
}

static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot)
{
        pud_t pud;

        if (!arch_vmap_pud_supported(prot))
                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(*pudp, __pud(0));
        WARN_ON(!pud_set_huge(pudp, __pfn_to_phys(pfn), prot));
        WARN_ON(!pud_clear_huge(pudp));
        pud = READ_ONCE(*pudp);
        WARN_ON(!pud_none(pud));
}
#else /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot) { }
static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot) { }
#endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */

static void __init p4d_basic_tests(unsigned long pfn, pgprot_t prot)
{
        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(unsigned long pfn, pgprot_t prot)
{
        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 mm_struct *mm, pud_t *pudp)
{
        pud_t pud = READ_ONCE(*pudp);

        if (mm_pmd_folded(mm))
                return;

        pr_debug("Validating PUD clear\n");
        pud = __pud(pud_val(pud) | RANDOM_ORVALUE);
        WRITE_ONCE(*pudp, pud);
        pud_clear(pudp);
        pud = READ_ONCE(*pudp);
        WARN_ON(!pud_none(pud));
}

static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
                                      pmd_t *pmdp)
{
        pud_t pud;

        if (mm_pmd_folded(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(mm, pudp, pmdp);
        pud = READ_ONCE(*pudp);
        WARN_ON(pud_bad(pud));
}
#else  /* !__PAGETABLE_PUD_FOLDED */
static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp) { }
static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
                                      pmd_t *pmdp)
{
}
#endif /* PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_P4D_FOLDED
static void __init p4d_clear_tests(struct mm_struct *mm, p4d_t *p4dp)
{
        p4d_t p4d = READ_ONCE(*p4dp);

        if (mm_pud_folded(mm))
                return;

        pr_debug("Validating P4D clear\n");
        p4d = __p4d(p4d_val(p4d) | RANDOM_ORVALUE);
        WRITE_ONCE(*p4dp, p4d);
        p4d_clear(p4dp);
        p4d = READ_ONCE(*p4dp);
        WARN_ON(!p4d_none(p4d));
}

static void __init p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp,
                                      pud_t *pudp)
{
        p4d_t p4d;

        if (mm_pud_folded(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(pudp);
        p4d_clear(p4dp);
        p4d_populate(mm, p4dp, pudp);
        p4d = READ_ONCE(*p4dp);
        WARN_ON(p4d_bad(p4d));
}

static void __init pgd_clear_tests(struct mm_struct *mm, pgd_t *pgdp)
{
        pgd_t pgd = READ_ONCE(*pgdp);

        if (mm_p4d_folded(mm))
                return;

        pr_debug("Validating PGD clear\n");
        pgd = __pgd(pgd_val(pgd) | RANDOM_ORVALUE);
        WRITE_ONCE(*pgdp, pgd);
        pgd_clear(pgdp);
        pgd = READ_ONCE(*pgdp);
        WARN_ON(!pgd_none(pgd));
}

static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp,
                                      p4d_t *p4dp)
{
        pgd_t pgd;

        if (mm_p4d_folded(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(p4dp);
        pgd_clear(pgdp);
        pgd_populate(mm, pgdp, p4dp);
        pgd = READ_ONCE(*pgdp);
        WARN_ON(pgd_bad(pgd));
}
#else  /* !__PAGETABLE_P4D_FOLDED */
static void __init p4d_clear_tests(struct mm_struct *mm, p4d_t *p4dp) { }
static void __init pgd_clear_tests(struct mm_struct *mm, pgd_t *pgdp) { }
static void __init p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp,
                                      pud_t *pudp)
{
}
static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp,
                                      p4d_t *p4dp)
{
}
#endif /* PAGETABLE_P4D_FOLDED */

static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep,
                                   unsigned long pfn, unsigned long vaddr,
                                   pgprot_t prot)
{
        pte_t pte = pfn_pte(pfn, prot);

        pr_debug("Validating PTE clear\n");
#ifndef CONFIG_RISCV
        pte = __pte(pte_val(pte) | RANDOM_ORVALUE);
#endif
        set_pte_at(mm, vaddr, ptep, pte);
        barrier();
        pte_clear(mm, vaddr, ptep);
        pte = ptep_get(ptep);
        WARN_ON(!pte_none(pte));
}

static void __init pmd_clear_tests(struct mm_struct *mm, pmd_t *pmdp)
{
        pmd_t pmd = READ_ONCE(*pmdp);

        pr_debug("Validating PMD clear\n");
        pmd = __pmd(pmd_val(pmd) | RANDOM_ORVALUE);
        WRITE_ONCE(*pmdp, pmd);
        pmd_clear(pmdp);
        pmd = READ_ONCE(*pmdp);
        WARN_ON(!pmd_none(pmd));
}

static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp,
                                      pgtable_t pgtable)
{
        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(mm, pmdp, pgtable);
        pmd = READ_ONCE(*pmdp);
        WARN_ON(pmd_bad(pmd));
}

static void __init pte_special_tests(unsigned long pfn, pgprot_t prot)
{
        pte_t pte = pfn_pte(pfn, 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(unsigned long pfn, pgprot_t prot)
{
        pte_t pte = pfn_pte(pfn, prot);

        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(unsigned long pfn, pgprot_t prot)
{
        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(pfn, prot));
        WARN_ON(!pmd_protnone(pmd));
        WARN_ON(!pmd_present(pmd));
}
#else  /* !CONFIG_TRANSPARENT_HUGEPAGE */
static void __init pmd_protnone_tests(unsigned long pfn, pgprot_t prot) { }
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

#ifdef CONFIG_ARCH_HAS_PTE_DEVMAP
static void __init pte_devmap_tests(unsigned long pfn, pgprot_t prot)
{
        pte_t pte = pfn_pte(pfn, prot);

        pr_debug("Validating PTE devmap\n");
        WARN_ON(!pte_devmap(pte_mkdevmap(pte)));
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_devmap_tests(unsigned long pfn, pgprot_t prot)
{
        pmd_t pmd;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD devmap\n");
        pmd = pfn_pmd(pfn, prot);
        WARN_ON(!pmd_devmap(pmd_mkdevmap(pmd)));
}

#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static void __init pud_devmap_tests(unsigned long pfn, pgprot_t prot)
{
        pud_t pud;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PUD devmap\n");
        pud = pfn_pud(pfn, prot);
        WARN_ON(!pud_devmap(pud_mkdevmap(pud)));
}
#else  /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
static void __init pud_devmap_tests(unsigned long pfn, pgprot_t prot) { }
#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
#else  /* CONFIG_TRANSPARENT_HUGEPAGE */
static void __init pmd_devmap_tests(unsigned long pfn, pgprot_t prot) { }
static void __init pud_devmap_tests(unsigned long pfn, pgprot_t prot) { }
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#else
static void __init pte_devmap_tests(unsigned long pfn, pgprot_t prot) { }
static void __init pmd_devmap_tests(unsigned long pfn, pgprot_t prot) { }
static void __init pud_devmap_tests(unsigned long pfn, pgprot_t prot) { }
#endif /* CONFIG_ARCH_HAS_PTE_DEVMAP */

static void __init pte_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
{
        pte_t pte = pfn_pte(pfn, prot);

        if (!IS_ENABLED(CONFIG_MEM_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(unsigned long pfn, pgprot_t prot)
{
        pte_t pte = pfn_pte(pfn, prot);

        if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
                return;

        pr_debug("Validating PTE swap soft dirty\n");
        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(unsigned long pfn, pgprot_t prot)
{
        pmd_t pmd;

        if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
                return;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD soft dirty\n");
        pmd = pfn_pmd(pfn, prot);
        WARN_ON(!pmd_soft_dirty(pmd_mksoft_dirty(pmd)));
        WARN_ON(pmd_soft_dirty(pmd_clear_soft_dirty(pmd)));
}

static void __init pmd_swap_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
{
        pmd_t pmd;

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

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD swap soft dirty\n");
        pmd = pfn_pmd(pfn, prot);
        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(unsigned long pfn, pgprot_t prot) { }
static void __init pmd_swap_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
{
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

static void __init pte_swap_tests(unsigned long pfn, pgprot_t prot)
{
        swp_entry_t swp;
        pte_t pte;

        pr_debug("Validating PTE swap\n");
        pte = pfn_pte(pfn, prot);
        swp = __pte_to_swp_entry(pte);
        pte = __swp_entry_to_pte(swp);
        WARN_ON(pfn != pte_pfn(pte));
}

#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
static void __init pmd_swap_tests(unsigned long pfn, pgprot_t prot)
{
        swp_entry_t swp;
        pmd_t pmd;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PMD swap\n");
        pmd = pfn_pmd(pfn, prot);
        swp = __pmd_to_swp_entry(pmd);
        pmd = __swp_entry_to_pmd(swp);
        WARN_ON(pfn != pmd_pfn(pmd));
}
#else  /* !CONFIG_ARCH_ENABLE_THP_MIGRATION */
static void __init pmd_swap_tests(unsigned long pfn, pgprot_t prot) { }
#endif /* CONFIG_ARCH_ENABLE_THP_MIGRATION */

static void __init swap_migration_tests(void)
{
        struct page *page;
        swp_entry_t swp;

        if (!IS_ENABLED(CONFIG_MIGRATION))
                return;

        pr_debug("Validating swap migration\n");
        /*
         * 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 allocate a dedicated page explicitly for this
         * purpose that will be freed subsequently.
         */
        page = alloc_page(GFP_KERNEL);
        if (!page) {
                pr_err("page allocation failed\n");
                return;
        }

        /*
         * make_migration_entry() expects given page to be
         * locked, otherwise it stumbles upon a BUG_ON().
         */
        __SetPageLocked(page);
        swp = make_writable_migration_entry(page_to_pfn(page));
        WARN_ON(!is_migration_entry(swp));
        WARN_ON(!is_writable_migration_entry(swp));

        swp = make_readable_migration_entry(swp_offset(swp));
        WARN_ON(!is_migration_entry(swp));
        WARN_ON(is_writable_migration_entry(swp));

        swp = make_readable_migration_entry(page_to_pfn(page));
        WARN_ON(!is_migration_entry(swp));
        WARN_ON(is_writable_migration_entry(swp));
        __ClearPageLocked(page);
        __free_page(page);
}

#ifdef CONFIG_HUGETLB_PAGE
static void __init hugetlb_basic_tests(unsigned long pfn, pgprot_t prot)
{
        struct page *page;
        pte_t pte;

        pr_debug("Validating HugeTLB basic\n");
        /*
         * Accessing the page associated with the pfn is safe here,
         * as it was previously derived from a real kernel symbol.
         */
        page = pfn_to_page(pfn);
        pte = mk_huge_pte(page, prot);

        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))));

#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
        pte = pfn_pte(pfn, prot);

        WARN_ON(!pte_huge(pte_mkhuge(pte)));
#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
}
#else  /* !CONFIG_HUGETLB_PAGE */
static void __init hugetlb_basic_tests(unsigned long pfn, pgprot_t prot) { }
#endif /* CONFIG_HUGETLB_PAGE */

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_thp_tests(unsigned long pfn, pgprot_t prot)
{
        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(pfn, 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))));
#endif /* __HAVE_ARCH_PMDP_INVALIDATE */
}

#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static void __init pud_thp_tests(unsigned long pfn, pgprot_t prot)
{
        pud_t pud;

        if (!has_transparent_hugepage())
                return;

        pr_debug("Validating PUD based THP\n");
        pud = pfn_pud(pfn, 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(unsigned long pfn, pgprot_t prot) { }
#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
#else  /* !CONFIG_TRANSPARENT_HUGEPAGE */
static void __init pmd_thp_tests(unsigned long pfn, pgprot_t prot) { }
static void __init pud_thp_tests(unsigned long pfn, pgprot_t prot) { }
#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 int __init debug_vm_pgtable(void)
{
        struct vm_area_struct *vma;
        struct mm_struct *mm;
        pgd_t *pgdp;
        p4d_t *p4dp, *saved_p4dp;
        pud_t *pudp, *saved_pudp;
        pmd_t *pmdp, *saved_pmdp, pmd;
        pte_t *ptep;
        pgtable_t saved_ptep;
        pgprot_t prot, protnone;
        phys_addr_t paddr;
        unsigned long vaddr, pte_aligned, pmd_aligned;
        unsigned long pud_aligned, p4d_aligned, pgd_aligned;
        spinlock_t *ptl = NULL;
        int idx;

        pr_info("Validating architecture page table helpers\n");
        prot = vm_get_page_prot(VMFLAGS);
        vaddr = get_random_vaddr();
        mm = mm_alloc();
        if (!mm) {
                pr_err("mm_struct allocation failed\n");
                return 1;
        }

        /*
         * __P000 (or even __S000) will help create page table entries with
         * PROT_NONE permission as required for pxx_protnone_tests().
         */
        protnone = __P000;

        vma = vm_area_alloc(mm);
        if (!vma) {
                pr_err("vma allocation failed\n");
                return 1;
        }

        /*
         * PFN for mapping at PTE level is determined from a standard kernel
         * text symbol. But pfns for higher page table levels are derived by
         * masking lower bits of this real pfn. These derived pfns might not
         * exist on the platform but that does not really matter as pfn_pxx()

         * helpers will still create appropriate entries for the test. This
         * helps avoid large memory block allocations to be used for mapping
         * at higher page table levels.
         */
        paddr = __pa_symbol(&start_kernel);

        pte_aligned = (paddr & PAGE_MASK) >> PAGE_SHIFT;
        pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT;
        pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT;
        p4d_aligned = (paddr & P4D_MASK) >> PAGE_SHIFT;
        pgd_aligned = (paddr & PGDIR_MASK) >> PAGE_SHIFT;
        WARN_ON(!pfn_valid(pte_aligned));

        pgdp = pgd_offset(mm, vaddr);
        p4dp = p4d_alloc(mm, pgdp, vaddr);
        pudp = pud_alloc(mm, p4dp, vaddr);
        pmdp = pmd_alloc(mm, pudp, vaddr);
        /*
         * Allocate pgtable_t
         */
        if (pte_alloc(mm, pmdp)) {
                pr_err("pgtable allocation failed\n");
                return 1;
        }

        /*
         * Save all the page table page addresses as the page table
         * entries will be used for testing with random or garbage
         * values. These saved addresses will be used for freeing
         * page table pages.
         */
        pmd = READ_ONCE(*pmdp);
        saved_p4dp = p4d_offset(pgdp, 0UL);
        saved_pudp = pud_offset(p4dp, 0UL);
        saved_pmdp = pmd_offset(pudp, 0UL);
        saved_ptep = pmd_pgtable(pmd);

        /*
         * Iterate over the protection_map[] 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.
         */
        for (idx = 0; idx < ARRAY_SIZE(protection_map); idx++) {
                pte_basic_tests(pte_aligned, idx);
                pmd_basic_tests(pmd_aligned, idx);
                pud_basic_tests(mm, pud_aligned, 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(p4d_aligned, prot);
        pgd_basic_tests(pgd_aligned, prot);

        pmd_leaf_tests(pmd_aligned, prot);
        pud_leaf_tests(pud_aligned, prot);

        pte_savedwrite_tests(pte_aligned, protnone);
        pmd_savedwrite_tests(pmd_aligned, protnone);

        pte_special_tests(pte_aligned, prot);
        pte_protnone_tests(pte_aligned, protnone);
        pmd_protnone_tests(pmd_aligned, protnone);

        pte_devmap_tests(pte_aligned, prot);
        pmd_devmap_tests(pmd_aligned, prot);
        pud_devmap_tests(pud_aligned, prot);

        pte_soft_dirty_tests(pte_aligned, prot);
        pmd_soft_dirty_tests(pmd_aligned, prot);
        pte_swap_soft_dirty_tests(pte_aligned, prot);
        pmd_swap_soft_dirty_tests(pmd_aligned, prot);

        pte_swap_tests(pte_aligned, prot);
        pmd_swap_tests(pmd_aligned, prot);

        swap_migration_tests();

        pmd_thp_tests(pmd_aligned, prot);
        pud_thp_tests(pud_aligned, prot);

        hugetlb_basic_tests(pte_aligned, prot);

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

        ptep = pte_offset_map_lock(mm, pmdp, vaddr, &ptl);
        pte_clear_tests(mm, ptep, pte_aligned, vaddr, prot);
        pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot);
        pte_unmap_unlock(ptep, ptl);

        ptl = pmd_lock(mm, pmdp);
        pmd_clear_tests(mm, pmdp);
        pmd_advanced_tests(mm, vma, pmdp, pmd_aligned, vaddr, prot, saved_ptep);
        pmd_huge_tests(pmdp, pmd_aligned, prot);
        pmd_populate_tests(mm, pmdp, saved_ptep);
        spin_unlock(ptl);

        ptl = pud_lock(mm, pudp);
        pud_clear_tests(mm, pudp);
        pud_advanced_tests(mm, vma, pudp, pud_aligned, vaddr, prot);
        pud_huge_tests(pudp, pud_aligned, prot);
        pud_populate_tests(mm, pudp, saved_pmdp);
        spin_unlock(ptl);

        spin_lock(&mm->page_table_lock);
        p4d_clear_tests(mm, p4dp);
        pgd_clear_tests(mm, pgdp);
        p4d_populate_tests(mm, p4dp, saved_pudp);
        pgd_populate_tests(mm, pgdp, saved_p4dp);
        spin_unlock(&mm->page_table_lock);

        p4d_free(mm, saved_p4dp);
        pud_free(mm, saved_pudp);
        pmd_free(mm, saved_pmdp);
        pte_free(mm, saved_ptep);

        vm_area_free(vma);
        mm_dec_nr_puds(mm);
        mm_dec_nr_pmds(mm);
        mm_dec_nr_ptes(mm);
        mmdrop(mm);
        return 0;
}
late_initcall(debug_vm_pgtable);