[mirror_ubuntu-kernels.git] / 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: %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);

	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);

	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);
Commit	Line	Data
399145f9 AK	1	// SPDX-License-Identifier: GPL-2.0-only
	2	/*
	3	* This kernel test validates architecture page table helpers and
	4	* accessors and helps in verifying their continued compliance with
	5	* expected generic MM semantics.
	6	*
	7	* Copyright (C) 2019 ARM Ltd.
	8	*
	9	* Author: Anshuman Khandual <anshuman.khandual@arm.com>
	10	*/
	11	#define pr_fmt(fmt) "debug_vm_pgtable: %s: " fmt, __func__
	12
	13	#include <linux/gfp.h>
	14	#include <linux/highmem.h>
	15	#include <linux/hugetlb.h>
	16	#include <linux/kernel.h>
	17	#include <linux/kconfig.h>
	18	#include <linux/mm.h>
	19	#include <linux/mman.h>
	20	#include <linux/mm_types.h>
	21	#include <linux/module.h>
	22	#include <linux/pfn_t.h>
	23	#include <linux/printk.h>
	24	#include <linux/random.h>
	25	#include <linux/spinlock.h>
	26	#include <linux/swap.h>
	27	#include <linux/swapops.h>
	28	#include <linux/start_kernel.h>
	29	#include <linux/sched/mm.h>
	30	#include <asm/pgalloc.h>
399145f9 AK	31
	32	#define VMFLAGS (VM_READ\|VM_WRITE\|VM_EXEC)
	33
	34	/*
	35	* On s390 platform, the lower 4 bits are used to identify given page table
	36	* entry type. But these bits might affect the ability to clear entries with
	37	* pxx_clear() because of how dynamic page table folding works on s390. So
	38	* while loading up the entries do not change the lower 4 bits. It does not
	39	* have affect any other platform.
	40	*/
	41	#define S390_MASK_BITS 4
	42	#define RANDOM_ORVALUE GENMASK(BITS_PER_LONG - 1, S390_MASK_BITS)
	43	#define RANDOM_NZVALUE GENMASK(7, 0)
	44
	45	static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot)
	46	{
	47	pte_t pte = pfn_pte(pfn, prot);
	48
	49	WARN_ON(!pte_same(pte, pte));
	50	WARN_ON(!pte_young(pte_mkyoung(pte_mkold(pte))));
	51	WARN_ON(!pte_dirty(pte_mkdirty(pte_mkclean(pte))));
	52	WARN_ON(!pte_write(pte_mkwrite(pte_wrprotect(pte))));
	53	WARN_ON(pte_young(pte_mkold(pte_mkyoung(pte))));
	54	WARN_ON(pte_dirty(pte_mkclean(pte_mkdirty(pte))));
	55	WARN_ON(pte_write(pte_wrprotect(pte_mkwrite(pte))));
	56	}
	57
	58	#ifdef CONFIG_TRANSPARENT_HUGEPAGE
	59	static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot)
	60	{
	61	pmd_t pmd = pfn_pmd(pfn, prot);
	62
	63	WARN_ON(!pmd_same(pmd, pmd));
	64	WARN_ON(!pmd_young(pmd_mkyoung(pmd_mkold(pmd))));
	65	WARN_ON(!pmd_dirty(pmd_mkdirty(pmd_mkclean(pmd))));
	66	WARN_ON(!pmd_write(pmd_mkwrite(pmd_wrprotect(pmd))));
	67	WARN_ON(pmd_young(pmd_mkold(pmd_mkyoung(pmd))));
	68	WARN_ON(pmd_dirty(pmd_mkclean(pmd_mkdirty(pmd))));
	69	WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite(pmd))));
	70	/*
	71	* A huge page does not point to next level page table
	72	* entry. Hence this must qualify as pmd_bad().
	73	*/
	74	WARN_ON(!pmd_bad(pmd_mkhuge(pmd)));
	75	}
	76
	77	#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
	78	static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot)
	79	{
	80	pud_t pud = pfn_pud(pfn, prot);
	81
	82	WARN_ON(!pud_same(pud, pud));
	83	WARN_ON(!pud_young(pud_mkyoung(pud_mkold(pud))));
	84	WARN_ON(!pud_write(pud_mkwrite(pud_wrprotect(pud))));
	85	WARN_ON(pud_write(pud_wrprotect(pud_mkwrite(pud))));
	86	WARN_ON(pud_young(pud_mkold(pud_mkyoung(pud))));
	87
	88	if (mm_pmd_folded(mm))
	89	return;
	90
	91	/*
	92	* A huge page does not point to next level page table
	93	* entry. Hence this must qualify as pud_bad().
	94	*/
95	WARN_ON(!pud_bad(pud_mkhuge(pud)));
96	}
97	#else /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
98	static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) { }
99	#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
100	#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
101	static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot) { }
102	static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) { }
103	#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
104
105	static void __init p4d_basic_tests(unsigned long pfn, pgprot_t prot)
106	{
107	p4d_t p4d;
108
109	memset(&p4d, RANDOM_NZVALUE, sizeof(p4d_t));
110	WARN_ON(!p4d_same(p4d, p4d));
111	}
112
113	static void __init pgd_basic_tests(unsigned long pfn, pgprot_t prot)
114	{
115	pgd_t pgd;
116
117	memset(&pgd, RANDOM_NZVALUE, sizeof(pgd_t));
118	WARN_ON(!pgd_same(pgd, pgd));
119	}
120
121	#ifndef __PAGETABLE_PUD_FOLDED
122	static void __init pud_clear_tests(struct mm_struct mm, pud_t pudp)
123	{
124	pud_t pud = READ_ONCE(*pudp);
125
126	if (mm_pmd_folded(mm))
127	return;
128
129	pud = __pud(pud_val(pud) \| RANDOM_ORVALUE);
130	WRITE_ONCE(*pudp, pud);
131	pud_clear(pudp);
132	pud = READ_ONCE(*pudp);
133	WARN_ON(!pud_none(pud));
134	}
135
136	static void __init pud_populate_tests(struct mm_struct mm, pud_t pudp,
137	pmd_t *pmdp)
138	{
139	pud_t pud;
140
141	if (mm_pmd_folded(mm))
142	return;
143	/*
144	* This entry points to next level page table page.
145	* Hence this must not qualify as pud_bad().
146	*/
147	pmd_clear(pmdp);
148	pud_clear(pudp);
149	pud_populate(mm, pudp, pmdp);
150	pud = READ_ONCE(*pudp);
151	WARN_ON(pud_bad(pud));
152	}
153	#else /* !__PAGETABLE_PUD_FOLDED */
154	static void __init pud_clear_tests(struct mm_struct mm, pud_t pudp) { }
155	static void __init pud_populate_tests(struct mm_struct mm, pud_t pudp,
156	pmd_t *pmdp)
157	{
158	}
159	#endif /* PAGETABLE_PUD_FOLDED */
160
161	#ifndef __PAGETABLE_P4D_FOLDED
162	static void __init p4d_clear_tests(struct mm_struct mm, p4d_t p4dp)
163	{
164	p4d_t p4d = READ_ONCE(*p4dp);
165
166	if (mm_pud_folded(mm))
167	return;
168
169	p4d = __p4d(p4d_val(p4d) \| RANDOM_ORVALUE);
170	WRITE_ONCE(*p4dp, p4d);
171	p4d_clear(p4dp);
172	p4d = READ_ONCE(*p4dp);
173	WARN_ON(!p4d_none(p4d));
174	}
175
176	static void __init p4d_populate_tests(struct mm_struct mm, p4d_t p4dp,
177	pud_t *pudp)
178	{
179	p4d_t p4d;
180
181	if (mm_pud_folded(mm))
182	return;
183
184	/*
185	* This entry points to next level page table page.
186	* Hence this must not qualify as p4d_bad().
187	*/
188	pud_clear(pudp);
189	p4d_clear(p4dp);
190	p4d_populate(mm, p4dp, pudp);
191	p4d = READ_ONCE(*p4dp);
192	WARN_ON(p4d_bad(p4d));
193	}
194
195	static void __init pgd_clear_tests(struct mm_struct mm, pgd_t pgdp)
196	{
197	pgd_t pgd = READ_ONCE(*pgdp);
198
199	if (mm_p4d_folded(mm))
200	return;
201
202	pgd = __pgd(pgd_val(pgd) \| RANDOM_ORVALUE);
203	WRITE_ONCE(*pgdp, pgd);
204	pgd_clear(pgdp);
205	pgd = READ_ONCE(*pgdp);
206	WARN_ON(!pgd_none(pgd));
207	}
208
209	static void __init pgd_populate_tests(struct mm_struct mm, pgd_t pgdp,
210	p4d_t *p4dp)
211	{
212	pgd_t pgd;
213
214	if (mm_p4d_folded(mm))
215	return;
216
217	/*
218	* This entry points to next level page table page.
219	* Hence this must not qualify as pgd_bad().
220	*/
221	p4d_clear(p4dp);
222	pgd_clear(pgdp);
223	pgd_populate(mm, pgdp, p4dp);
224	pgd = READ_ONCE(*pgdp);
225	WARN_ON(pgd_bad(pgd));
226	}
227	#else /* !__PAGETABLE_P4D_FOLDED */
228	static void __init p4d_clear_tests(struct mm_struct mm, p4d_t p4dp) { }
229	static void __init pgd_clear_tests(struct mm_struct mm, pgd_t pgdp) { }
230	static void __init p4d_populate_tests(struct mm_struct mm, p4d_t p4dp,
231	pud_t *pudp)
232	{
233	}
234	static void __init pgd_populate_tests(struct mm_struct mm, pgd_t pgdp,
235	p4d_t *p4dp)
236	{
237	}
238	#endif /* PAGETABLE_P4D_FOLDED */
239
240	static void __init pte_clear_tests(struct mm_struct mm, pte_t ptep,
241	unsigned long vaddr)
242	{
243	pte_t pte = READ_ONCE(*ptep);
244
245	pte = __pte(pte_val(pte) \| RANDOM_ORVALUE);
246	set_pte_at(mm, vaddr, ptep, pte);
247	barrier();
248	pte_clear(mm, vaddr, ptep);
249	pte = READ_ONCE(*ptep);
250	WARN_ON(!pte_none(pte));
251	}
252
253	static void __init pmd_clear_tests(struct mm_struct mm, pmd_t pmdp)
254	{
255	pmd_t pmd = READ_ONCE(*pmdp);
256
257	pmd = __pmd(pmd_val(pmd) \| RANDOM_ORVALUE);
258	WRITE_ONCE(*pmdp, pmd);
259	pmd_clear(pmdp);
260	pmd = READ_ONCE(*pmdp);
261	WARN_ON(!pmd_none(pmd));
262	}
263
264	static void __init pmd_populate_tests(struct mm_struct mm, pmd_t pmdp,
265	pgtable_t pgtable)
266	{
267	pmd_t pmd;
268
269	/*
270	* This entry points to next level page table page.
271	* Hence this must not qualify as pmd_bad().
272	*/
273	pmd_clear(pmdp);
274	pmd_populate(mm, pmdp, pgtable);
275	pmd = READ_ONCE(*pmdp);
276	WARN_ON(pmd_bad(pmd));
277	}
278
279	static unsigned long __init get_random_vaddr(void)
280	{
281	unsigned long random_vaddr, random_pages, total_user_pages;
282
283	total_user_pages = (TASK_SIZE - FIRST_USER_ADDRESS) / PAGE_SIZE;
284
285	random_pages = get_random_long() % total_user_pages;
286	random_vaddr = FIRST_USER_ADDRESS + random_pages * PAGE_SIZE;
287
288	return random_vaddr;
289	}
290
291	static int __init debug_vm_pgtable(void)
292	{
293	struct mm_struct *mm;
294	pgd_t *pgdp;
295	p4d_t p4dp, saved_p4dp;
296	pud_t pudp, saved_pudp;
297	pmd_t pmdp, saved_pmdp, pmd;
298	pte_t *ptep;
299	pgtable_t saved_ptep;
300	pgprot_t prot;
301	phys_addr_t paddr;
302	unsigned long vaddr, pte_aligned, pmd_aligned;
303	unsigned long pud_aligned, p4d_aligned, pgd_aligned;
304	spinlock_t *uninitialized_var(ptl);
305
306	pr_info("Validating architecture page table helpers\n");
307	prot = vm_get_page_prot(VMFLAGS);
308	vaddr = get_random_vaddr();
309	mm = mm_alloc();
310	if (!mm) {
311	pr_err("mm_struct allocation failed\n");
312	return 1;
313	}
314
315	/*
316	* PFN for mapping at PTE level is determined from a standard kernel
317	* text symbol. But pfns for higher page table levels are derived by
318	* masking lower bits of this real pfn. These derived pfns might not
319	* exist on the platform but that does not really matter as pfn_pxx()
320	* helpers will still create appropriate entries for the test. This
321	* helps avoid large memory block allocations to be used for mapping
322	* at higher page table levels.
323	*/
324	paddr = __pa_symbol(&start_kernel);
325
326	pte_aligned = (paddr & PAGE_MASK) >> PAGE_SHIFT;
327	pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT;
328	pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT;
329	p4d_aligned = (paddr & P4D_MASK) >> PAGE_SHIFT;
330	pgd_aligned = (paddr & PGDIR_MASK) >> PAGE_SHIFT;
331	WARN_ON(!pfn_valid(pte_aligned));
332
333	pgdp = pgd_offset(mm, vaddr);
334	p4dp = p4d_alloc(mm, pgdp, vaddr);
335	pudp = pud_alloc(mm, p4dp, vaddr);
336	pmdp = pmd_alloc(mm, pudp, vaddr);
337	ptep = pte_alloc_map_lock(mm, pmdp, vaddr, &ptl);
338
339	/*
340	* Save all the page table page addresses as the page table
341	* entries will be used for testing with random or garbage
342	* values. These saved addresses will be used for freeing
343	* page table pages.
344	*/
345	pmd = READ_ONCE(*pmdp);
346	saved_p4dp = p4d_offset(pgdp, 0UL);
347	saved_pudp = pud_offset(p4dp, 0UL);
348	saved_pmdp = pmd_offset(pudp, 0UL);
349	saved_ptep = pmd_pgtable(pmd);
350
351	pte_basic_tests(pte_aligned, prot);
352	pmd_basic_tests(pmd_aligned, prot);
353	pud_basic_tests(pud_aligned, prot);
354	p4d_basic_tests(p4d_aligned, prot);
355	pgd_basic_tests(pgd_aligned, prot);
356
357	pte_clear_tests(mm, ptep, vaddr);
358	pmd_clear_tests(mm, pmdp);
359	pud_clear_tests(mm, pudp);
360	p4d_clear_tests(mm, p4dp);
361	pgd_clear_tests(mm, pgdp);
362
363	pte_unmap_unlock(ptep, ptl);
364
365	pmd_populate_tests(mm, pmdp, saved_ptep);
366	pud_populate_tests(mm, pudp, saved_pmdp);
367	p4d_populate_tests(mm, p4dp, saved_pudp);
368	pgd_populate_tests(mm, pgdp, saved_p4dp);
369
370	p4d_free(mm, saved_p4dp);
371	pud_free(mm, saved_pudp);
372	pmd_free(mm, saved_pmdp);
373	pte_free(mm, saved_ptep);
374
375	mm_dec_nr_puds(mm);
376	mm_dec_nr_pmds(mm);
377	mm_dec_nr_ptes(mm);
378	mmdrop(mm);
379	return 0;
380	}
381	late_initcall(debug_vm_pgtable);