[linux-block.git] / mm / kasan / kasan_init.c

/*
 * This file contains some kasan initialization code.
 *
 * Copyright (c) 2015 Samsung Electronics Co., Ltd.
 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/bootmem.h>
#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/pfn.h>
#include <linux/slab.h>

#include <asm/page.h>
#include <asm/pgalloc.h>

#include "kasan.h"

/*
 * This page serves two purposes:
 *   - It used as early shadow memory. The entire shadow region populated
 *     with this page, before we will be able to setup normal shadow memory.
 *   - Latter it reused it as zero shadow to cover large ranges of memory
 *     that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
 */
unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;

#if CONFIG_PGTABLE_LEVELS > 4
p4d_t kasan_zero_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss;
static inline bool kasan_p4d_table(pgd_t pgd)
{
	return pgd_page(pgd) == virt_to_page(lm_alias(kasan_zero_p4d));
}
#else
static inline bool kasan_p4d_table(pgd_t pgd)
{
	return 0;
}
#endif
#if CONFIG_PGTABLE_LEVELS > 3
pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
static inline bool kasan_pud_table(p4d_t p4d)
{
	return p4d_page(p4d) == virt_to_page(lm_alias(kasan_zero_pud));
}
#else
static inline bool kasan_pud_table(p4d_t p4d)
{
	return 0;
}
#endif
#if CONFIG_PGTABLE_LEVELS > 2
pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
static inline bool kasan_pmd_table(pud_t pud)
{
	return pud_page(pud) == virt_to_page(lm_alias(kasan_zero_pmd));
}
#else
static inline bool kasan_pmd_table(pud_t pud)
{
	return 0;
}
#endif
pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;

static inline bool kasan_pte_table(pmd_t pmd)
{
	return pmd_page(pmd) == virt_to_page(lm_alias(kasan_zero_pte));
}

static inline bool kasan_zero_page_entry(pte_t pte)
{
	return pte_page(pte) == virt_to_page(lm_alias(kasan_zero_page));
}

static __init void *early_alloc(size_t size, int node)
{
	return memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
					BOOTMEM_ALLOC_ACCESSIBLE, node);
}

static void __ref zero_pte_populate(pmd_t *pmd, unsigned long addr,
				unsigned long end)
{
	pte_t *pte = pte_offset_kernel(pmd, addr);
	pte_t zero_pte;

	zero_pte = pfn_pte(PFN_DOWN(__pa_symbol(kasan_zero_page)), PAGE_KERNEL);
	zero_pte = pte_wrprotect(zero_pte);

	while (addr + PAGE_SIZE <= end) {
		set_pte_at(&init_mm, addr, pte, zero_pte);
		addr += PAGE_SIZE;
		pte = pte_offset_kernel(pmd, addr);
	}
}

static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr,
				unsigned long end)
{
	pmd_t *pmd = pmd_offset(pud, addr);
	unsigned long next;

	do {
		next = pmd_addr_end(addr, end);

		if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
			pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
			continue;
		}

		if (pmd_none(*pmd)) {
			pte_t *p;

			if (slab_is_available())
				p = pte_alloc_one_kernel(&init_mm, addr);
			else
				p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
			if (!p)
				return -ENOMEM;

			pmd_populate_kernel(&init_mm, pmd, p);
		}
		zero_pte_populate(pmd, addr, next);
	} while (pmd++, addr = next, addr != end);

	return 0;
}

static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr,
				unsigned long end)
{
	pud_t *pud = pud_offset(p4d, addr);
	unsigned long next;

	do {
		next = pud_addr_end(addr, end);
		if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
			pmd_t *pmd;

			pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
			pmd = pmd_offset(pud, addr);
			pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
			continue;
		}

		if (pud_none(*pud)) {
			pmd_t *p;

			if (slab_is_available()) {
				p = pmd_alloc(&init_mm, pud, addr);
				if (!p)
					return -ENOMEM;
			} else {
				pud_populate(&init_mm, pud,
					early_alloc(PAGE_SIZE, NUMA_NO_NODE));
			}
		}
		zero_pmd_populate(pud, addr, next);
	} while (pud++, addr = next, addr != end);

	return 0;
}

static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
				unsigned long end)
{
	p4d_t *p4d = p4d_offset(pgd, addr);
	unsigned long next;

	do {
		next = p4d_addr_end(addr, end);
		if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) {
			pud_t *pud;
			pmd_t *pmd;

			p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud));
			pud = pud_offset(p4d, addr);
			pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
			pmd = pmd_offset(pud, addr);
			pmd_populate_kernel(&init_mm, pmd,
						lm_alias(kasan_zero_pte));
			continue;
		}

		if (p4d_none(*p4d)) {
			pud_t *p;

			if (slab_is_available()) {
				p = pud_alloc(&init_mm, p4d, addr);
				if (!p)
					return -ENOMEM;
			} else {
				p4d_populate(&init_mm, p4d,
					early_alloc(PAGE_SIZE, NUMA_NO_NODE));
			}
		}
		zero_pud_populate(p4d, addr, next);
	} while (p4d++, addr = next, addr != end);

	return 0;
}

/**
 * kasan_populate_zero_shadow - populate shadow memory region with
 *                               kasan_zero_page
 * @shadow_start - start of the memory range to populate
 * @shadow_end   - end of the memory range to populate
 */
int __ref kasan_populate_zero_shadow(const void *shadow_start,
				const void *shadow_end)
{
	unsigned long addr = (unsigned long)shadow_start;
	unsigned long end = (unsigned long)shadow_end;
	pgd_t *pgd = pgd_offset_k(addr);
	unsigned long next;

	do {
		next = pgd_addr_end(addr, end);

		if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
			p4d_t *p4d;
			pud_t *pud;
			pmd_t *pmd;

			/*
			 * kasan_zero_pud should be populated with pmds
			 * at this moment.
			 * [pud,pmd]_populate*() below needed only for
			 * 3,2 - level page tables where we don't have
			 * puds,pmds, so pgd_populate(), pud_populate()
			 * is noops.
			 *
			 * The ifndef is required to avoid build breakage.
			 *
			 * With 5level-fixup.h, pgd_populate() is not nop and
			 * we reference kasan_zero_p4d. It's not defined
			 * unless 5-level paging enabled.
			 *
			 * The ifndef can be dropped once all KASAN-enabled
			 * architectures will switch to pgtable-nop4d.h.
			 */
#ifndef __ARCH_HAS_5LEVEL_HACK
			pgd_populate(&init_mm, pgd, lm_alias(kasan_zero_p4d));
#endif
			p4d = p4d_offset(pgd, addr);
			p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud));
			pud = pud_offset(p4d, addr);
			pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
			pmd = pmd_offset(pud, addr);
			pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
			continue;
		}

		if (pgd_none(*pgd)) {
			p4d_t *p;

			if (slab_is_available()) {
				p = p4d_alloc(&init_mm, pgd, addr);
				if (!p)
					return -ENOMEM;
			} else {
				pgd_populate(&init_mm, pgd,
					early_alloc(PAGE_SIZE, NUMA_NO_NODE));
			}
		}
		zero_p4d_populate(pgd, addr, next);
	} while (pgd++, addr = next, addr != end);

	return 0;
}

static void kasan_free_pte(pte_t *pte_start, pmd_t *pmd)
{
	pte_t *pte;
	int i;

	for (i = 0; i < PTRS_PER_PTE; i++) {
		pte = pte_start + i;
		if (!pte_none(*pte))
			return;
	}

	pte_free_kernel(&init_mm, (pte_t *)page_to_virt(pmd_page(*pmd)));
	pmd_clear(pmd);
}

static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud)
{
	pmd_t *pmd;
	int i;

	for (i = 0; i < PTRS_PER_PMD; i++) {
		pmd = pmd_start + i;
		if (!pmd_none(*pmd))
			return;
	}

	pmd_free(&init_mm, (pmd_t *)page_to_virt(pud_page(*pud)));
	pud_clear(pud);
}

static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d)
{
	pud_t *pud;
	int i;

	for (i = 0; i < PTRS_PER_PUD; i++) {
		pud = pud_start + i;
		if (!pud_none(*pud))
			return;
	}

	pud_free(&init_mm, (pud_t *)page_to_virt(p4d_page(*p4d)));
	p4d_clear(p4d);
}

static void kasan_free_p4d(p4d_t *p4d_start, pgd_t *pgd)
{
	p4d_t *p4d;
	int i;

	for (i = 0; i < PTRS_PER_P4D; i++) {
		p4d = p4d_start + i;
		if (!p4d_none(*p4d))
			return;
	}

	p4d_free(&init_mm, (p4d_t *)page_to_virt(pgd_page(*pgd)));
	pgd_clear(pgd);
}

static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
				unsigned long end)
{
	unsigned long next;

	for (; addr < end; addr = next, pte++) {
		next = (addr + PAGE_SIZE) & PAGE_MASK;
		if (next > end)
			next = end;

		if (!pte_present(*pte))
			continue;

		if (WARN_ON(!kasan_zero_page_entry(*pte)))
			continue;
		pte_clear(&init_mm, addr, pte);
	}
}

static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
				unsigned long end)
{
	unsigned long next;

	for (; addr < end; addr = next, pmd++) {
		pte_t *pte;

		next = pmd_addr_end(addr, end);

		if (!pmd_present(*pmd))
			continue;

		if (kasan_pte_table(*pmd)) {
			if (IS_ALIGNED(addr, PMD_SIZE) &&
			    IS_ALIGNED(next, PMD_SIZE))
				pmd_clear(pmd);
			continue;
		}
		pte = pte_offset_kernel(pmd, addr);
		kasan_remove_pte_table(pte, addr, next);
		kasan_free_pte(pte_offset_kernel(pmd, 0), pmd);
	}
}

static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
				unsigned long end)
{
	unsigned long next;

	for (; addr < end; addr = next, pud++) {
		pmd_t *pmd, *pmd_base;

		next = pud_addr_end(addr, end);

		if (!pud_present(*pud))
			continue;

		if (kasan_pmd_table(*pud)) {
			if (IS_ALIGNED(addr, PUD_SIZE) &&
			    IS_ALIGNED(next, PUD_SIZE))
				pud_clear(pud);
			continue;
		}
		pmd = pmd_offset(pud, addr);
		pmd_base = pmd_offset(pud, 0);
		kasan_remove_pmd_table(pmd, addr, next);
		kasan_free_pmd(pmd_base, pud);
	}
}

static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
				unsigned long end)
{
	unsigned long next;

	for (; addr < end; addr = next, p4d++) {
		pud_t *pud;

		next = p4d_addr_end(addr, end);

		if (!p4d_present(*p4d))
			continue;

		if (kasan_pud_table(*p4d)) {
			if (IS_ALIGNED(addr, P4D_SIZE) &&
			    IS_ALIGNED(next, P4D_SIZE))
				p4d_clear(p4d);
			continue;
		}
		pud = pud_offset(p4d, addr);
		kasan_remove_pud_table(pud, addr, next);
		kasan_free_pud(pud_offset(p4d, 0), p4d);
	}
}

void kasan_remove_zero_shadow(void *start, unsigned long size)
{
	unsigned long addr, end, next;
	pgd_t *pgd;

	addr = (unsigned long)kasan_mem_to_shadow(start);
	end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);

	if (WARN_ON((unsigned long)start %
			(KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
	    WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
		return;

	for (; addr < end; addr = next) {
		p4d_t *p4d;

		next = pgd_addr_end(addr, end);

		pgd = pgd_offset_k(addr);
		if (!pgd_present(*pgd))
			continue;

		if (kasan_p4d_table(*pgd)) {
			if (IS_ALIGNED(addr, PGDIR_SIZE) &&
			    IS_ALIGNED(next, PGDIR_SIZE))
				pgd_clear(pgd);
			continue;
		}

		p4d = p4d_offset(pgd, addr);
		kasan_remove_p4d_table(p4d, addr, next);
		kasan_free_p4d(p4d_offset(pgd, 0), pgd);
	}
}

int kasan_add_zero_shadow(void *start, unsigned long size)
{
	int ret;
	void *shadow_start, *shadow_end;

	shadow_start = kasan_mem_to_shadow(start);
	shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);

	if (WARN_ON((unsigned long)start %
			(KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
	    WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
		return -EINVAL;

	ret = kasan_populate_zero_shadow(shadow_start, shadow_end);
	if (ret)
		kasan_remove_zero_shadow(shadow_start,
					size >> KASAN_SHADOW_SCALE_SHIFT);
	return ret;
}
Commit	Line	Data
69786cdb AR	1	/*
	2	* This file contains some kasan initialization code.
	3	*
	4	* Copyright (c) 2015 Samsung Electronics Co., Ltd.
	5	* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*
	11	*/
	12
	13	#include <linux/bootmem.h>
	14	#include <linux/init.h>
	15	#include <linux/kasan.h>
	16	#include <linux/kernel.h>
	17	#include <linux/memblock.h>
5c6a84a3	18	#include <linux/mm.h>
69786cdb	19	#include <linux/pfn.h>
0207df4f	20	#include <linux/slab.h>
69786cdb AR	21
	22	#include <asm/page.h>
	23	#include <asm/pgalloc.h>
	24
0207df4f AR	25	#include "kasan.h"
0207df4f AR	26
69786cdb AR	27	/*
	28	* This page serves two purposes:
	29	* - It used as early shadow memory. The entire shadow region populated
	30	* with this page, before we will be able to setup normal shadow memory.
	31	* - Latter it reused it as zero shadow to cover large ranges of memory
	32	* that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
	33	*/
	34	unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
	35
c2febafc	36	#if CONFIG_PGTABLE_LEVELS > 4
c65e774f	37	p4d_t kasan_zero_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss;
0207df4f AR	38	static inline bool kasan_p4d_table(pgd_t pgd)
	39	{
	40	return pgd_page(pgd) == virt_to_page(lm_alias(kasan_zero_p4d));
	41	}
	42	#else
	43	static inline bool kasan_p4d_table(pgd_t pgd)
	44	{
	45	return 0;
	46	}
c2febafc	47	#endif
69786cdb AR	48	#if CONFIG_PGTABLE_LEVELS > 3
69786cdb AR	49	pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
0207df4f AR	50	static inline bool kasan_pud_table(p4d_t p4d)
	51	{
	52	return p4d_page(p4d) == virt_to_page(lm_alias(kasan_zero_pud));
	53	}
	54	#else
	55	static inline bool kasan_pud_table(p4d_t p4d)
	56	{
	57	return 0;
	58	}
69786cdb AR	59	#endif
	60	#if CONFIG_PGTABLE_LEVELS > 2
	61	pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
0207df4f AR	62	static inline bool kasan_pmd_table(pud_t pud)
	63	{
	64	return pud_page(pud) == virt_to_page(lm_alias(kasan_zero_pmd));
	65	}
	66	#else
	67	static inline bool kasan_pmd_table(pud_t pud)
	68	{
	69	return 0;
	70	}
69786cdb AR	71	#endif
	72	pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
	73
0207df4f AR	74	static inline bool kasan_pte_table(pmd_t pmd)
	75	{
	76	return pmd_page(pmd) == virt_to_page(lm_alias(kasan_zero_pte));
	77	}
	78
	79	static inline bool kasan_zero_page_entry(pte_t pte)
	80	{
	81	return pte_page(pte) == virt_to_page(lm_alias(kasan_zero_page));
	82	}
	83
69786cdb AR	84	static __init void *early_alloc(size_t size, int node)
69786cdb AR	85	{
eb31d559	86	return memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
69786cdb AR	87	BOOTMEM_ALLOC_ACCESSIBLE, node);
	88	}
	89
0207df4f	90	static void __ref zero_pte_populate(pmd_t *pmd, unsigned long addr,
69786cdb AR	91	unsigned long end)
	92	{
	93	pte_t *pte = pte_offset_kernel(pmd, addr);
	94	pte_t zero_pte;
	95
5c6a84a3	96	zero_pte = pfn_pte(PFN_DOWN(__pa_symbol(kasan_zero_page)), PAGE_KERNEL);
69786cdb AR	97	zero_pte = pte_wrprotect(zero_pte);
	98
	99	while (addr + PAGE_SIZE <= end) {
	100	set_pte_at(&init_mm, addr, pte, zero_pte);
	101	addr += PAGE_SIZE;
	102	pte = pte_offset_kernel(pmd, addr);
	103	}
	104	}
	105
0207df4f	106	static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr,
69786cdb AR	107	unsigned long end)
	108	{
	109	pmd_t *pmd = pmd_offset(pud, addr);
	110	unsigned long next;
	111
	112	do {
	113	next = pmd_addr_end(addr, end);
	114
	115	if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
5c6a84a3	116	pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
69786cdb AR	117	continue;
	118	}
	119
	120	if (pmd_none(*pmd)) {
0207df4f AR	121	pte_t *p;
	122
	123	if (slab_is_available())
	124	p = pte_alloc_one_kernel(&init_mm, addr);
	125	else
	126	p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
	127	if (!p)
	128	return -ENOMEM;
	129
	130	pmd_populate_kernel(&init_mm, pmd, p);
69786cdb AR	131	}
	132	zero_pte_populate(pmd, addr, next);
	133	} while (pmd++, addr = next, addr != end);
0207df4f AR	134
0207df4f AR	135	return 0;
69786cdb AR	136	}
69786cdb AR	137
0207df4f	138	static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr,
69786cdb AR	139	unsigned long end)
69786cdb AR	140	{
c2febafc	141	pud_t *pud = pud_offset(p4d, addr);
69786cdb AR	142	unsigned long next;
	143
	144	do {
	145	next = pud_addr_end(addr, end);
	146	if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
	147	pmd_t *pmd;
	148
5c6a84a3	149	pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
69786cdb	150	pmd = pmd_offset(pud, addr);
5c6a84a3	151	pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
69786cdb AR	152	continue;
	153	}
	154
	155	if (pud_none(*pud)) {
0207df4f AR	156	pmd_t *p;
	157
	158	if (slab_is_available()) {
	159	p = pmd_alloc(&init_mm, pud, addr);
	160	if (!p)
	161	return -ENOMEM;
	162	} else {
	163	pud_populate(&init_mm, pud,
	164	early_alloc(PAGE_SIZE, NUMA_NO_NODE));
	165	}
69786cdb AR	166	}
	167	zero_pmd_populate(pud, addr, next);
	168	} while (pud++, addr = next, addr != end);
0207df4f AR	169
0207df4f AR	170	return 0;
69786cdb AR	171	}
69786cdb AR	172
0207df4f	173	static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
c2febafc KS	174	unsigned long end)
	175	{
	176	p4d_t *p4d = p4d_offset(pgd, addr);
	177	unsigned long next;
	178
	179	do {
	180	next = p4d_addr_end(addr, end);
458f7920 JK	181	if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) {
	182	pud_t *pud;
	183	pmd_t *pmd;
	184
	185	p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud));
	186	pud = pud_offset(p4d, addr);
	187	pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
	188	pmd = pmd_offset(pud, addr);
	189	pmd_populate_kernel(&init_mm, pmd,
	190	lm_alias(kasan_zero_pte));
	191	continue;
	192	}
c2febafc KS	193
c2febafc KS	194	if (p4d_none(*p4d)) {
0207df4f AR	195	pud_t *p;
	196
	197	if (slab_is_available()) {
	198	p = pud_alloc(&init_mm, p4d, addr);
	199	if (!p)
	200	return -ENOMEM;
	201	} else {
	202	p4d_populate(&init_mm, p4d,
	203	early_alloc(PAGE_SIZE, NUMA_NO_NODE));
	204	}
c2febafc KS	205	}
	206	zero_pud_populate(p4d, addr, next);
	207	} while (p4d++, addr = next, addr != end);
0207df4f AR	208
0207df4f AR	209	return 0;
c2febafc KS	210	}
c2febafc KS	211
69786cdb AR	212	/**
	213	* kasan_populate_zero_shadow - populate shadow memory region with
	214	* kasan_zero_page
	215	* @shadow_start - start of the memory range to populate
	216	* @shadow_end - end of the memory range to populate
	217	*/
0207df4f	218	int __ref kasan_populate_zero_shadow(const void *shadow_start,
69786cdb AR	219	const void *shadow_end)
	220	{
	221	unsigned long addr = (unsigned long)shadow_start;
	222	unsigned long end = (unsigned long)shadow_end;
	223	pgd_t *pgd = pgd_offset_k(addr);
	224	unsigned long next;
	225
	226	do {
	227	next = pgd_addr_end(addr, end);
	228
	229	if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
c2febafc	230	p4d_t *p4d;
69786cdb AR	231	pud_t *pud;
	232	pmd_t *pmd;
	233
	234	/*
	235	* kasan_zero_pud should be populated with pmds
	236	* at this moment.
	237	* [pud,pmd]_populate*() below needed only for
	238	* 3,2 - level page tables where we don't have
	239	* puds,pmds, so pgd_populate(), pud_populate()
	240	* is noops.
c2febafc KS	241	*
	242	* The ifndef is required to avoid build breakage.
	243	*
	244	* With 5level-fixup.h, pgd_populate() is not nop and
	245	* we reference kasan_zero_p4d. It's not defined
	246	* unless 5-level paging enabled.
	247	*
	248	* The ifndef can be dropped once all KASAN-enabled
	249	* architectures will switch to pgtable-nop4d.h.
69786cdb	250	*/
c2febafc KS	251	#ifndef __ARCH_HAS_5LEVEL_HACK
	252	pgd_populate(&init_mm, pgd, lm_alias(kasan_zero_p4d));
	253	#endif
	254	p4d = p4d_offset(pgd, addr);
	255	p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud));
	256	pud = pud_offset(p4d, addr);
5c6a84a3	257	pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
69786cdb	258	pmd = pmd_offset(pud, addr);
5c6a84a3	259	pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
69786cdb AR	260	continue;
	261	}
	262
	263	if (pgd_none(*pgd)) {
0207df4f AR	264	p4d_t *p;
	265
	266	if (slab_is_available()) {
	267	p = p4d_alloc(&init_mm, pgd, addr);
	268	if (!p)
	269	return -ENOMEM;
	270	} else {
	271	pgd_populate(&init_mm, pgd,
	272	early_alloc(PAGE_SIZE, NUMA_NO_NODE));
	273	}
69786cdb	274	}
c2febafc	275	zero_p4d_populate(pgd, addr, next);
69786cdb	276	} while (pgd++, addr = next, addr != end);
0207df4f AR	277
	278	return 0;
	279	}
	280
	281	static void kasan_free_pte(pte_t pte_start, pmd_t pmd)
	282	{
	283	pte_t *pte;
	284	int i;
	285
	286	for (i = 0; i < PTRS_PER_PTE; i++) {
	287	pte = pte_start + i;
	288	if (!pte_none(*pte))
	289	return;
	290	}
	291
	292	pte_free_kernel(&init_mm, (pte_t )page_to_virt(pmd_page(pmd)));
	293	pmd_clear(pmd);
	294	}
	295
	296	static void kasan_free_pmd(pmd_t pmd_start, pud_t pud)
	297	{
	298	pmd_t *pmd;
	299	int i;
	300
	301	for (i = 0; i < PTRS_PER_PMD; i++) {
	302	pmd = pmd_start + i;
	303	if (!pmd_none(*pmd))
	304	return;
	305	}
	306
	307	pmd_free(&init_mm, (pmd_t )page_to_virt(pud_page(pud)));
	308	pud_clear(pud);
	309	}
	310
	311	static void kasan_free_pud(pud_t pud_start, p4d_t p4d)
	312	{
	313	pud_t *pud;
	314	int i;
	315
	316	for (i = 0; i < PTRS_PER_PUD; i++) {
	317	pud = pud_start + i;
	318	if (!pud_none(*pud))
	319	return;
	320	}
	321
	322	pud_free(&init_mm, (pud_t )page_to_virt(p4d_page(p4d)));
	323	p4d_clear(p4d);
	324	}
	325
	326	static void kasan_free_p4d(p4d_t p4d_start, pgd_t pgd)
	327	{
	328	p4d_t *p4d;
	329	int i;
	330
	331	for (i = 0; i < PTRS_PER_P4D; i++) {
	332	p4d = p4d_start + i;
	333	if (!p4d_none(*p4d))
	334	return;
	335	}
	336
	337	p4d_free(&init_mm, (p4d_t )page_to_virt(pgd_page(pgd)));
	338	pgd_clear(pgd);
	339	}
	340
341	static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
342	unsigned long end)
343	{
344	unsigned long next;
345
346	for (; addr < end; addr = next, pte++) {
347	next = (addr + PAGE_SIZE) & PAGE_MASK;
348	if (next > end)
349	next = end;
350
351	if (!pte_present(*pte))
352	continue;
353
354	if (WARN_ON(!kasan_zero_page_entry(*pte)))
355	continue;
356	pte_clear(&init_mm, addr, pte);
357	}
358	}
359
360	static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
361	unsigned long end)
362	{
363	unsigned long next;
364
365	for (; addr < end; addr = next, pmd++) {
366	pte_t *pte;
367
368	next = pmd_addr_end(addr, end);
369
370	if (!pmd_present(*pmd))
371	continue;
372
373	if (kasan_pte_table(*pmd)) {
374	if (IS_ALIGNED(addr, PMD_SIZE) &&
375	IS_ALIGNED(next, PMD_SIZE))
376	pmd_clear(pmd);
377	continue;
378	}
379	pte = pte_offset_kernel(pmd, addr);
380	kasan_remove_pte_table(pte, addr, next);
381	kasan_free_pte(pte_offset_kernel(pmd, 0), pmd);
382	}
383	}
384
385	static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
386	unsigned long end)
387	{
388	unsigned long next;
389
390	for (; addr < end; addr = next, pud++) {
391	pmd_t pmd, pmd_base;
392
393	next = pud_addr_end(addr, end);
394
395	if (!pud_present(*pud))
396	continue;
397
398	if (kasan_pmd_table(*pud)) {
399	if (IS_ALIGNED(addr, PUD_SIZE) &&
400	IS_ALIGNED(next, PUD_SIZE))
401	pud_clear(pud);
402	continue;
403	}
404	pmd = pmd_offset(pud, addr);
405	pmd_base = pmd_offset(pud, 0);
406	kasan_remove_pmd_table(pmd, addr, next);
407	kasan_free_pmd(pmd_base, pud);
408	}
409	}
410
411	static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
412	unsigned long end)
413	{
414	unsigned long next;
415
416	for (; addr < end; addr = next, p4d++) {
417	pud_t *pud;
418
419	next = p4d_addr_end(addr, end);
420
421	if (!p4d_present(*p4d))
422	continue;
423
424	if (kasan_pud_table(*p4d)) {
425	if (IS_ALIGNED(addr, P4D_SIZE) &&
426	IS_ALIGNED(next, P4D_SIZE))
427	p4d_clear(p4d);
428	continue;
429	}
430	pud = pud_offset(p4d, addr);
431	kasan_remove_pud_table(pud, addr, next);
432	kasan_free_pud(pud_offset(p4d, 0), p4d);
433	}
434	}
435
436	void kasan_remove_zero_shadow(void *start, unsigned long size)
437	{
438	unsigned long addr, end, next;
439	pgd_t *pgd;
440
441	addr = (unsigned long)kasan_mem_to_shadow(start);
442	end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
443
444	if (WARN_ON((unsigned long)start %
445	(KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) \|\|
446	WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
447	return;
448
449	for (; addr < end; addr = next) {
450	p4d_t *p4d;
451
452	next = pgd_addr_end(addr, end);
453
454	pgd = pgd_offset_k(addr);
455	if (!pgd_present(*pgd))
456	continue;
457
458	if (kasan_p4d_table(*pgd)) {
459	if (IS_ALIGNED(addr, PGDIR_SIZE) &&
460	IS_ALIGNED(next, PGDIR_SIZE))
461	pgd_clear(pgd);
462	continue;
463	}
464
465	p4d = p4d_offset(pgd, addr);
466	kasan_remove_p4d_table(p4d, addr, next);
467	kasan_free_p4d(p4d_offset(pgd, 0), pgd);
468	}
469	}
470
471	int kasan_add_zero_shadow(void *start, unsigned long size)
472	{
473	int ret;
474	void shadow_start, shadow_end;
475
476	shadow_start = kasan_mem_to_shadow(start);
477	shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);
478
479	if (WARN_ON((unsigned long)start %
480	(KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) \|\|
481	WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
482	return -EINVAL;
483
484	ret = kasan_populate_zero_shadow(shadow_start, shadow_end);
485	if (ret)
486	kasan_remove_zero_shadow(shadow_start,
487	size >> KASAN_SHADOW_SCALE_SHIFT);
488	return ret;
69786cdb	489	}