// 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: %s: " 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/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 <asm/pgalloc.h>
#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.
*/
#define S390_MASK_BITS 4
#define RANDOM_ORVALUE GENMASK(BITS_PER_LONG - 1, S390_MASK_BITS)
#define RANDOM_NZVALUE GENMASK(7, 0)
static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot)
{
pte_t pte = pfn_pte(pfn, prot);
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))));
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot)
{
pmd_t pmd = pfn_pmd(pfn, prot);
if (!has_transparent_hugepage())
return;
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))));
/*
* 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)));
}
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot)
{
pud_t pud = pfn_pud(pfn, prot);
if (!has_transparent_hugepage())
return;
WARN_ON(!pud_same(pud, pud));
WARN_ON(!pud_young(pud_mkyoung(pud_mkold(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))));
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)));
}
#else /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
static void __init pud_basic_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, pgprot_t prot) { }
static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) { }
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
static void __init p4d_basic_tests(unsigned long pfn, pgprot_t prot)
{
p4d_t p4d;
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;
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;
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;
/*
* This entry points to next level page table page.
* Hence this must not qualify as pud_bad().
*/
pmd_clear(pmdp);
pud_clear(pudp);
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;
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;
/*
* 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;
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;
/*
* 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 vaddr)
{
pte_t pte = READ_ONCE(*ptep);
pte = __pte(pte_val(pte) | RANDOM_ORVALUE);
set_pte_at(mm, vaddr, ptep, pte);
barrier();
pte_clear(mm, vaddr, ptep);
pte = READ_ONCE(*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);
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;
/*
* This entry points to next level page table page.
* Hence this must not qualify as pmd_bad().
*/
pmd_clear(pmdp);
pmd_populate(mm, pmdp, pgtable);
pmd = READ_ONCE(*pmdp);
WARN_ON(pmd_bad(pmd));
}
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 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;
phys_addr_t paddr;
unsigned long vaddr, pte_aligned, pmd_aligned;
unsigned long pud_aligned, p4d_aligned, pgd_aligned;
spinlock_t *uninitialized_var(ptl);
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;
}
/*
* 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);
ptep = pte_alloc_map_lock(mm, pmdp, vaddr, &ptl);
/*
* 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);
pte_basic_tests(pte_aligned, prot);
pmd_basic_tests(pmd_aligned, prot);
pud_basic_tests(pud_aligned, prot);
p4d_basic_tests(p4d_aligned, prot);
pgd_basic_tests(pgd_aligned, prot);
pte_clear_tests(mm, ptep, vaddr);
pmd_clear_tests(mm, pmdp);
pud_clear_tests(mm, pudp);
p4d_clear_tests(mm, p4dp);
pgd_clear_tests(mm, pgdp);
pte_unmap_unlock(ptep, ptl);
pmd_populate_tests(mm, pmdp, saved_ptep);
pud_populate_tests(mm, pudp, saved_pmdp);
p4d_populate_tests(mm, p4dp, saved_pudp);
pgd_populate_tests(mm, pgdp, saved_p4dp);
p4d_free(mm, saved_p4dp);
pud_free(mm, saved_pudp);
pmd_free(mm, saved_pmdp);
pte_free(mm, saved_ptep);
mm_dec_nr_puds(mm);
mm_dec_nr_pmds(mm);
mm_dec_nr_ptes(mm);
mmdrop(mm);
return 0;
}
late_initcall(debug_vm_pgtable);
