path: root/mm/debug_vm_pgtable.c

// 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/cacheflush.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)

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_pgd_pfn;
	unsigned long		fixed_p4d_pfn;
	unsigned long		fixed_pud_pfn;
	unsigned long		fixed_pmd_pfn;
	unsigned long		fixed_pte_pfn;
};

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(!