[linux-2.6-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/memblock.h>
#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.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),
					MEMBLOCK_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
57c8a661	13	#include <linux/memblock.h>
69786cdb AR	14	#include <linux/init.h>
	15	#include <linux/kasan.h>
	16	#include <linux/kernel.h>
5c6a84a3	17	#include <linux/mm.h>
69786cdb	18	#include <linux/pfn.h>
0207df4f	19	#include <linux/slab.h>
69786cdb AR	20
	21	#include <asm/page.h>
	22	#include <asm/pgalloc.h>
	23
0207df4f AR	24	#include "kasan.h"
0207df4f AR	25
69786cdb AR	26	/*
	27	* This page serves two purposes:
	28	* - It used as early shadow memory. The entire shadow region populated
	29	* with this page, before we will be able to setup normal shadow memory.
	30	* - Latter it reused it as zero shadow to cover large ranges of memory
	31	* that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
	32	*/
	33	unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
	34
c2febafc	35	#if CONFIG_PGTABLE_LEVELS > 4
c65e774f	36	p4d_t kasan_zero_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss;
0207df4f AR	37	static inline bool kasan_p4d_table(pgd_t pgd)
	38	{
	39	return pgd_page(pgd) == virt_to_page(lm_alias(kasan_zero_p4d));
	40	}
	41	#else
	42	static inline bool kasan_p4d_table(pgd_t pgd)
	43	{
	44	return 0;
	45	}
c2febafc	46	#endif
69786cdb AR	47	#if CONFIG_PGTABLE_LEVELS > 3
69786cdb AR	48	pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
0207df4f AR	49	static inline bool kasan_pud_table(p4d_t p4d)
	50	{
	51	return p4d_page(p4d) == virt_to_page(lm_alias(kasan_zero_pud));
	52	}
	53	#else
	54	static inline bool kasan_pud_table(p4d_t p4d)
	55	{
	56	return 0;
	57	}
69786cdb AR	58	#endif
	59	#if CONFIG_PGTABLE_LEVELS > 2
	60	pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
0207df4f AR	61	static inline bool kasan_pmd_table(pud_t pud)
	62	{
	63	return pud_page(pud) == virt_to_page(lm_alias(kasan_zero_pmd));
	64	}
	65	#else
	66	static inline bool kasan_pmd_table(pud_t pud)
	67	{
	68	return 0;
	69	}
69786cdb AR	70	#endif
	71	pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
	72
0207df4f AR	73	static inline bool kasan_pte_table(pmd_t pmd)
	74	{
	75	return pmd_page(pmd) == virt_to_page(lm_alias(kasan_zero_pte));
	76	}
	77
	78	static inline bool kasan_zero_page_entry(pte_t pte)
	79	{
	80	return pte_page(pte) == virt_to_page(lm_alias(kasan_zero_page));
	81	}
	82
69786cdb AR	83	static __init void *early_alloc(size_t size, int node)
69786cdb AR	84	{
eb31d559	85	return memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
97ad1087	86	MEMBLOCK_ALLOC_ACCESSIBLE, node);
69786cdb AR	87	}
69786cdb AR	88
0207df4f	89	static void __ref zero_pte_populate(pmd_t *pmd, unsigned long addr,
69786cdb AR	90	unsigned long end)
	91	{
	92	pte_t *pte = pte_offset_kernel(pmd, addr);
	93	pte_t zero_pte;
	94
5c6a84a3	95	zero_pte = pfn_pte(PFN_DOWN(__pa_symbol(kasan_zero_page)), PAGE_KERNEL);
69786cdb AR	96	zero_pte = pte_wrprotect(zero_pte);
	97
	98	while (addr + PAGE_SIZE <= end) {
	99	set_pte_at(&init_mm, addr, pte, zero_pte);
	100	addr += PAGE_SIZE;
	101	pte = pte_offset_kernel(pmd, addr);
	102	}
	103	}
	104
0207df4f	105	static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr,
69786cdb AR	106	unsigned long end)
	107	{
	108	pmd_t *pmd = pmd_offset(pud, addr);
	109	unsigned long next;
	110
	111	do {
	112	next = pmd_addr_end(addr, end);
	113
	114	if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
5c6a84a3	115	pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
69786cdb AR	116	continue;
	117	}
	118
	119	if (pmd_none(*pmd)) {
0207df4f AR	120	pte_t *p;
	121
	122	if (slab_is_available())
	123	p = pte_alloc_one_kernel(&init_mm, addr);
	124	else
	125	p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
	126	if (!p)
	127	return -ENOMEM;
	128
	129	pmd_populate_kernel(&init_mm, pmd, p);
69786cdb AR	130	}
	131	zero_pte_populate(pmd, addr, next);
	132	} while (pmd++, addr = next, addr != end);
0207df4f AR	133
0207df4f AR	134	return 0;
69786cdb AR	135	}
69786cdb AR	136
0207df4f	137	static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr,
69786cdb AR	138	unsigned long end)
69786cdb AR	139	{
c2febafc	140	pud_t *pud = pud_offset(p4d, addr);
69786cdb AR	141	unsigned long next;
	142
	143	do {
	144	next = pud_addr_end(addr, end);
	145	if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
	146	pmd_t *pmd;
	147
5c6a84a3	148	pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
69786cdb	149	pmd = pmd_offset(pud, addr);
5c6a84a3	150	pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
69786cdb AR	151	continue;
	152	}
	153
	154	if (pud_none(*pud)) {
0207df4f AR	155	pmd_t *p;
	156
	157	if (slab_is_available()) {
	158	p = pmd_alloc(&init_mm, pud, addr);
	159	if (!p)
	160	return -ENOMEM;
	161	} else {
	162	pud_populate(&init_mm, pud,
	163	early_alloc(PAGE_SIZE, NUMA_NO_NODE));
	164	}
69786cdb AR	165	}
	166	zero_pmd_populate(pud, addr, next);
	167	} while (pud++, addr = next, addr != end);
0207df4f AR	168
0207df4f AR	169	return 0;
69786cdb AR	170	}
69786cdb AR	171
0207df4f	172	static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
c2febafc KS	173	unsigned long end)
	174	{
	175	p4d_t *p4d = p4d_offset(pgd, addr);
	176	unsigned long next;
	177
	178	do {
	179	next = p4d_addr_end(addr, end);
458f7920 JK	180	if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) {
	181	pud_t *pud;
	182	pmd_t *pmd;
	183
	184	p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud));
	185	pud = pud_offset(p4d, addr);
	186	pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
	187	pmd = pmd_offset(pud, addr);
	188	pmd_populate_kernel(&init_mm, pmd,
	189	lm_alias(kasan_zero_pte));
	190	continue;
	191	}
c2febafc KS	192
c2febafc KS	193	if (p4d_none(*p4d)) {
0207df4f AR	194	pud_t *p;
	195
	196	if (slab_is_available()) {
	197	p = pud_alloc(&init_mm, p4d, addr);
	198	if (!p)
	199	return -ENOMEM;
	200	} else {
	201	p4d_populate(&init_mm, p4d,
	202	early_alloc(PAGE_SIZE, NUMA_NO_NODE));
	203	}
c2febafc KS	204	}
	205	zero_pud_populate(p4d, addr, next);
	206	} while (p4d++, addr = next, addr != end);
0207df4f AR	207
0207df4f AR	208	return 0;
c2febafc KS	209	}
c2febafc KS	210
69786cdb AR	211	/**
	212	* kasan_populate_zero_shadow - populate shadow memory region with
	213	* kasan_zero_page
	214	* @shadow_start - start of the memory range to populate
	215	* @shadow_end - end of the memory range to populate
	216	*/
0207df4f	217	int __ref kasan_populate_zero_shadow(const void *shadow_start,
69786cdb AR	218	const void *shadow_end)
	219	{
	220	unsigned long addr = (unsigned long)shadow_start;
	221	unsigned long end = (unsigned long)shadow_end;
	222	pgd_t *pgd = pgd_offset_k(addr);
	223	unsigned long next;
	224
	225	do {
	226	next = pgd_addr_end(addr, end);
	227
	228	if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
c2febafc	229	p4d_t *p4d;
69786cdb AR	230	pud_t *pud;
	231	pmd_t *pmd;
	232
	233	/*
	234	* kasan_zero_pud should be populated with pmds
	235	* at this moment.
	236	* [pud,pmd]_populate*() below needed only for
	237	* 3,2 - level page tables where we don't have
	238	* puds,pmds, so pgd_populate(), pud_populate()
	239	* is noops.
c2febafc KS	240	*
	241	* The ifndef is required to avoid build breakage.
	242	*
	243	* With 5level-fixup.h, pgd_populate() is not nop and
	244	* we reference kasan_zero_p4d. It's not defined
	245	* unless 5-level paging enabled.
	246	*
	247	* The ifndef can be dropped once all KASAN-enabled
	248	* architectures will switch to pgtable-nop4d.h.
69786cdb	249	*/
c2febafc KS	250	#ifndef __ARCH_HAS_5LEVEL_HACK
	251	pgd_populate(&init_mm, pgd, lm_alias(kasan_zero_p4d));
	252	#endif
	253	p4d = p4d_offset(pgd, addr);
	254	p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud));
	255	pud = pud_offset(p4d, addr);
5c6a84a3	256	pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
69786cdb	257	pmd = pmd_offset(pud, addr);
5c6a84a3	258	pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
69786cdb AR	259	continue;
	260	}
	261
	262	if (pgd_none(*pgd)) {
0207df4f AR	263	p4d_t *p;
	264
	265	if (slab_is_available()) {
	266	p = p4d_alloc(&init_mm, pgd, addr);
	267	if (!p)
	268	return -ENOMEM;
	269	} else {
	270	pgd_populate(&init_mm, pgd,
	271	early_alloc(PAGE_SIZE, NUMA_NO_NODE));
	272	}
69786cdb	273	}
c2febafc	274	zero_p4d_populate(pgd, addr, next);
69786cdb	275	} while (pgd++, addr = next, addr != end);
0207df4f AR	276
	277	return 0;
	278	}
	279
	280	static void kasan_free_pte(pte_t pte_start, pmd_t pmd)
	281	{
	282	pte_t *pte;
	283	int i;
	284
	285	for (i = 0; i < PTRS_PER_PTE; i++) {
	286	pte = pte_start + i;
	287	if (!pte_none(*pte))
	288	return;
	289	}
	290
	291	pte_free_kernel(&init_mm, (pte_t )page_to_virt(pmd_page(pmd)));
	292	pmd_clear(pmd);
	293	}
	294
	295	static void kasan_free_pmd(pmd_t pmd_start, pud_t pud)
	296	{
	297	pmd_t *pmd;
	298	int i;
	299
	300	for (i = 0; i < PTRS_PER_PMD; i++) {
	301	pmd = pmd_start + i;
	302	if (!pmd_none(*pmd))
	303	return;
	304	}
	305
	306	pmd_free(&init_mm, (pmd_t )page_to_virt(pud_page(pud)));
	307	pud_clear(pud);
	308	}
	309
	310	static void kasan_free_pud(pud_t pud_start, p4d_t p4d)
	311	{
	312	pud_t *pud;
	313	int i;
	314
	315	for (i = 0; i < PTRS_PER_PUD; i++) {
	316	pud = pud_start + i;
	317	if (!pud_none(*pud))
	318	return;
	319	}
	320
	321	pud_free(&init_mm, (pud_t )page_to_virt(p4d_page(p4d)));
	322	p4d_clear(p4d);
	323	}
	324
	325	static void kasan_free_p4d(p4d_t p4d_start, pgd_t pgd)
	326	{
	327	p4d_t *p4d;
	328	int i;
	329
	330	for (i = 0; i < PTRS_PER_P4D; i++) {
	331	p4d = p4d_start + i;
	332	if (!p4d_none(*p4d))
	333	return;
	334	}
	335
	336	p4d_free(&init_mm, (p4d_t )page_to_virt(pgd_page(pgd)));
	337	pgd_clear(pgd);
	338	}
	339
340	static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
341	unsigned long end)
342	{
343	unsigned long next;
344
345	for (; addr < end; addr = next, pte++) {
346	next = (addr + PAGE_SIZE) & PAGE_MASK;
347	if (next > end)
348	next = end;
349
350	if (!pte_present(*pte))
351	continue;
352
353	if (WARN_ON(!kasan_zero_page_entry(*pte)))
354	continue;
355	pte_clear(&init_mm, addr, pte);
356	}
357	}
358
359	static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
360	unsigned long end)
361	{
362	unsigned long next;
363
364	for (; addr < end; addr = next, pmd++) {
365	pte_t *pte;
366
367	next = pmd_addr_end(addr, end);
368
369	if (!pmd_present(*pmd))
370	continue;
371
372	if (kasan_pte_table(*pmd)) {
373	if (IS_ALIGNED(addr, PMD_SIZE) &&
374	IS_ALIGNED(next, PMD_SIZE))
375	pmd_clear(pmd);
376	continue;
377	}
378	pte = pte_offset_kernel(pmd, addr);
379	kasan_remove_pte_table(pte, addr, next);
380	kasan_free_pte(pte_offset_kernel(pmd, 0), pmd);
381	}
382	}
383
384	static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
385	unsigned long end)
386	{
387	unsigned long next;
388
389	for (; addr < end; addr = next, pud++) {
390	pmd_t pmd, pmd_base;
391
392	next = pud_addr_end(addr, end);
393
394	if (!pud_present(*pud))
395	continue;
396
397	if (kasan_pmd_table(*pud)) {
398	if (IS_ALIGNED(addr, PUD_SIZE) &&
399	IS_ALIGNED(next, PUD_SIZE))
400	pud_clear(pud);
401	continue;
402	}
403	pmd = pmd_offset(pud, addr);
404	pmd_base = pmd_offset(pud, 0);
405	kasan_remove_pmd_table(pmd, addr, next);
406	kasan_free_pmd(pmd_base, pud);
407	}
408	}
409
410	static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
411	unsigned long end)
412	{
413	unsigned long next;
414
415	for (; addr < end; addr = next, p4d++) {
416	pud_t *pud;
417
418	next = p4d_addr_end(addr, end);
419
420	if (!p4d_present(*p4d))
421	continue;
422
423	if (kasan_pud_table(*p4d)) {
424	if (IS_ALIGNED(addr, P4D_SIZE) &&
425	IS_ALIGNED(next, P4D_SIZE))
426	p4d_clear(p4d);
427	continue;
428	}
429	pud = pud_offset(p4d, addr);
430	kasan_remove_pud_table(pud, addr, next);
431	kasan_free_pud(pud_offset(p4d, 0), p4d);
432	}
433	}
434
435	void kasan_remove_zero_shadow(void *start, unsigned long size)
436	{
437	unsigned long addr, end, next;
438	pgd_t *pgd;
439
440	addr = (unsigned long)kasan_mem_to_shadow(start);
441	end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
442
443	if (WARN_ON((unsigned long)start %
444	(KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) \|\|
445	WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
446	return;
447
448	for (; addr < end; addr = next) {
449	p4d_t *p4d;
450
451	next = pgd_addr_end(addr, end);
452
453	pgd = pgd_offset_k(addr);
454	if (!pgd_present(*pgd))
455	continue;
456
457	if (kasan_p4d_table(*pgd)) {
458	if (IS_ALIGNED(addr, PGDIR_SIZE) &&
459	IS_ALIGNED(next, PGDIR_SIZE))
460	pgd_clear(pgd);
461	continue;
462	}
463
464	p4d = p4d_offset(pgd, addr);
465	kasan_remove_p4d_table(p4d, addr, next);
466	kasan_free_p4d(p4d_offset(pgd, 0), pgd);
467	}
468	}
469
470	int kasan_add_zero_shadow(void *start, unsigned long size)
471	{
472	int ret;
473	void shadow_start, shadow_end;
474
475	shadow_start = kasan_mem_to_shadow(start);
476	shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);
477
478	if (WARN_ON((unsigned long)start %
479	(KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) \|\|
480	WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
481	return -EINVAL;
482
483	ret = kasan_populate_zero_shadow(shadow_start, shadow_end);
484	if (ret)
485	kasan_remove_zero_shadow(shadow_start,
486	size >> KASAN_SHADOW_SCALE_SHIFT);
487	return ret;
69786cdb	488	}