arch/x86/mm/kasan_init_64.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 #define DISABLE_BRANCH_PROFILING
 #define pr_fmt(fmt) "kasan: " fmt

 /* cpu_feature_enabled() cannot be used this early */
 #define USE_EARLY_PGTABLE_L5

 #include <linux/memblock.h>
 #include <linux/kasan.h>
 #include <linux/kdebug.h>
 #include <linux/mm.h>
 #include <linux/sched.h>
 #include <linux/sched/task.h>
 #include <linux/vmalloc.h>

 #include <asm/e820/types.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
 #include <asm/sections.h>
 #include <asm/pgtable.h>
 #include <asm/cpu_entry_area.h>

 extern struct range pfn_mapped[E820_MAX_ENTRIES];

 static p4d_t tmp_p4d_table[MAX_PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);

 static __init void *early_alloc(size_t size, int nid, bool panic)
 {
 	if (panic)
 		return memblock_alloc_try_nid(size, size,
 			__pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, nid);
 	else
 		return memblock_alloc_try_nid_nopanic(size, size,
 			__pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, nid);
 }

 static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
 				      unsigned long end, int nid)
 {
 	pte_t *pte;

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

 		if (boot_cpu_has(X86_FEATURE_PSE) &&
 		    ((end - addr) == PMD_SIZE) &&
 		    IS_ALIGNED(addr, PMD_SIZE)) {
 			p = early_alloc(PMD_SIZE, nid, false);
 			if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
 				return;
 			else if (p)
 				memblock_free(__pa(p), PMD_SIZE);
 		}

 		p = early_alloc(PAGE_SIZE, nid, true);
 		pmd_populate_kernel(&init_mm, pmd, p);
 	}

 	pte = pte_offset_kernel(pmd, addr);
 	do {
 		pte_t entry;
 		void *p;

 		if (!pte_none(*pte))
 			continue;

 		p = early_alloc(PAGE_SIZE, nid, true);
 		entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
 		set_pte_at(&init_mm, addr, pte, entry);
 	} while (pte++, addr += PAGE_SIZE, addr != end);
 }

 static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
 				      unsigned long end, int nid)
 {
 	pmd_t *pmd;
 	unsigned long next;

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

 		if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
 		    ((end - addr) == PUD_SIZE) &&
 		    IS_ALIGNED(addr, PUD_SIZE)) {
 			p = early_alloc(PUD_SIZE, nid, false);
 			if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
 				return;
 			else if (p)
 				memblock_free(__pa(p), PUD_SIZE);
 		}

 		p = early_alloc(PAGE_SIZE, nid, true);
 		pud_populate(&init_mm, pud, p);
 	}

 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
 		if (!pmd_large(*pmd))
 			kasan_populate_pmd(pmd, addr, next, nid);
 	} while (pmd++, addr = next, addr != end);
 }

 static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
 				      unsigned long end, int nid)
 {
 	pud_t *pud;
 	unsigned long next;

 	if (p4d_none(*p4d)) {
 		void *p = early_alloc(PAGE_SIZE, nid, true);

 		p4d_populate(&init_mm, p4d, p);
 	}

 	pud = pud_offset(p4d, addr);
 	do {
 		next = pud_addr_end(addr, end);
 		if (!pud_large(*pud))
 			kasan_populate_pud(pud, addr, next, nid);
 	} while (pud++, addr = next, addr != end);
 }

 static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
 				      unsigned long end, int nid)
 {
 	void *p;
 	p4d_t *p4d;
 	unsigned long next;

 	if (pgd_none(*pgd)) {
 		p = early_alloc(PAGE_SIZE, nid, true);
 		pgd_populate(&init_mm, pgd, p);
 	}

 	p4d = p4d_offset(pgd, addr);
 	do {
 		next = p4d_addr_end(addr, end);
 		kasan_populate_p4d(p4d, addr, next, nid);
 	} while (p4d++, addr = next, addr != end);
 }

 static void __init kasan_populate_shadow(unsigned long addr, unsigned long end,
 					 int nid)
 {
 	pgd_t *pgd;
 	unsigned long next;

 	addr = addr & PAGE_MASK;
 	end = round_up(end, PAGE_SIZE);
 	pgd = pgd_offset_k(addr);
 	do {
 		next = pgd_addr_end(addr, end);
 		kasan_populate_pgd(pgd, addr, next, nid);
 	} while (pgd++, addr = next, addr != end);
 }

 static void __init map_range(struct range *range)
 {
 	unsigned long start;
 	unsigned long end;

 	start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
 	end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));

 	kasan_populate_shadow(start, end, early_pfn_to_nid(range->start));
 }

 static void __init clear_pgds(unsigned long start,
 			unsigned long end)
 {
 	pgd_t *pgd;
 	/* See comment in kasan_init() */
 	unsigned long pgd_end = end & PGDIR_MASK;

 	for (; start < pgd_end; start += PGDIR_SIZE) {
 		pgd = pgd_offset_k(start);
 		/*
 		 * With folded p4d, pgd_clear() is nop, use p4d_clear()
 		 * instead.
 		 */
 		if (pgtable_l5_enabled())
 			pgd_clear(pgd);
 		else
 			p4d_clear(p4d_offset(pgd, start));
 	}

 	pgd = pgd_offset_k(start);
 	for (; start < end; start += P4D_SIZE)
 		p4d_clear(p4d_offset(pgd, start));
 }

 static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
 {
 	unsigned long p4d;

 	if (!pgtable_l5_enabled())
 		return (p4d_t *)pgd;

 	p4d = __pa_nodebug(pgd_val(*pgd)) & PTE_PFN_MASK;
 	p4d += __START_KERNEL_map - phys_base;
 	return (p4d_t *)p4d + p4d_index(addr);
 }

 static void __init kasan_early_p4d_populate(pgd_t *pgd,
 		unsigned long addr,
 		unsigned long end)
 {
 	pgd_t pgd_entry;
 	p4d_t *p4d, p4d_entry;
 	unsigned long next;

 	if (pgd_none(*pgd)) {
 		pgd_entry = __pgd(_KERNPG_TABLE |
 					__pa_nodebug(kasan_early_shadow_p4d));
 		set_pgd(pgd, pgd_entry);
 	}

 	p4d = early_p4d_offset(pgd, addr);
 	do {
 		next = p4d_addr_end(addr, end);

 		if (!p4d_none(*p4d))
 			continue;

 		p4d_entry = __p4d(_KERNPG_TABLE |
 					__pa_nodebug(kasan_early_shadow_pud));
 		set_p4d(p4d, p4d_entry);
 	} while (p4d++, addr = next, addr != end && p4d_none(*p4d));
 }

 static void __init kasan_map_early_shadow(pgd_t *pgd)
 {
 	/* See comment in kasan_init() */
 	unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
 	unsigned long end = KASAN_SHADOW_END;
 	unsigned long next;

 	pgd += pgd_index(addr);
 	do {
 		next = pgd_addr_end(addr, end);
 		kasan_early_p4d_populate(pgd, addr, next);
 	} while (pgd++, addr = next, addr != end);
 }

 #ifdef CONFIG_KASAN_INLINE
 static int kasan_die_handler(struct notifier_block *self,
 			     unsigned long val,
 			     void *data)
 {
 	if (val == DIE_GPF) {
 		pr_emerg("CONFIG_KASAN_INLINE enabled\n");
 		pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
 	}
 	return NOTIFY_OK;
 }

 static struct notifier_block kasan_die_notifier = {
 	.notifier_call = kasan_die_handler,
 };
 #endif

 void __init kasan_early_init(void)
 {
 	int i;
 	pteval_t pte_val = __pa_nodebug(kasan_early_shadow_page) |
 				__PAGE_KERNEL | _PAGE_ENC;
 	pmdval_t pmd_val = __pa_nodebug(kasan_early_shadow_pte) | _KERNPG_TABLE;
 	pudval_t pud_val = __pa_nodebug(kasan_early_shadow_pmd) | _KERNPG_TABLE;
 	p4dval_t p4d_val = __pa_nodebug(kasan_early_shadow_pud) | _KERNPG_TABLE;

 	/* Mask out unsupported __PAGE_KERNEL bits: */
 	pte_val &= __default_kernel_pte_mask;
 	pmd_val &= __default_kernel_pte_mask;
 	pud_val &= __default_kernel_pte_mask;
 	p4d_val &= __default_kernel_pte_mask;

 	for (i = 0; i < PTRS_PER_PTE; i++)
 		kasan_early_shadow_pte[i] = __pte(pte_val);

 	for (i = 0; i < PTRS_PER_PMD; i++)
 		kasan_early_shadow_pmd[i] = __pmd(pmd_val);

 	for (i = 0; i < PTRS_PER_PUD; i++)
 		kasan_early_shadow_pud[i] = __pud(pud_val);

 	for (i = 0; pgtable_l5_enabled() && i < PTRS_PER_P4D; i++)
 		kasan_early_shadow_p4d[i] = __p4d(p4d_val);

 	kasan_map_early_shadow(early_top_pgt);
 	kasan_map_early_shadow(init_top_pgt);
 }

 void __init kasan_init(void)
 {
 	int i;
 	void *shadow_cpu_entry_begin, *shadow_cpu_entry_end;

 #ifdef CONFIG_KASAN_INLINE
 	register_die_notifier(&kasan_die_notifier);
 #endif

 	memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));

 	/*
 	 * We use the same shadow offset for 4- and 5-level paging to
 	 * facilitate boot-time switching between paging modes.
 	 * As result in 5-level paging mode KASAN_SHADOW_START and
 	 * KASAN_SHADOW_END are not aligned to PGD boundary.
 	 *
 	 * KASAN_SHADOW_START doesn't share PGD with anything else.
 	 * We claim whole PGD entry to make things easier.
 	 *
 	 * KASAN_SHADOW_END lands in the last PGD entry and it collides with
 	 * bunch of things like kernel code, modules, EFI mapping, etc.
 	 * We need to take extra steps to not overwrite them.
 	 */
 	if (pgtable_l5_enabled()) {
 		void *ptr;

 		ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
 		memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
 		set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
 				__pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
 	}

 	load_cr3(early_top_pgt);
 	__flush_tlb_all();

 	clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);

 	kasan_populate_early_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
 			kasan_mem_to_shadow((void *)PAGE_OFFSET));

 	for (i = 0; i < E820_MAX_ENTRIES; i++) {
 		if (pfn_mapped[i].end == 0)
 			break;

 		map_range(&pfn_mapped[i]);
 	}

 	shadow_cpu_entry_begin = (void *)CPU_ENTRY_AREA_BASE;
 	shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
 	shadow_cpu_entry_begin = (void *)round_down(
 			(unsigned long)shadow_cpu_entry_begin, PAGE_SIZE);

 	shadow_cpu_entry_end = (void *)(CPU_ENTRY_AREA_BASE +
 					CPU_ENTRY_AREA_MAP_SIZE);
 	shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
 	shadow_cpu_entry_end = (void *)round_up(
 			(unsigned long)shadow_cpu_entry_end, PAGE_SIZE);

 	kasan_populate_early_shadow(
 		kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
 		shadow_cpu_entry_begin);

 	kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
 			      (unsigned long)shadow_cpu_entry_end, 0);

 	kasan_populate_early_shadow(shadow_cpu_entry_end,
 			kasan_mem_to_shadow((void *)__START_KERNEL_map));

 	kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
 			      (unsigned long)kasan_mem_to_shadow(_end),
 			      early_pfn_to_nid(__pa(_stext)));

 	kasan_populate_early_shadow(kasan_mem_to_shadow((void *)MODULES_END),
 					(void *)KASAN_SHADOW_END);

 	load_cr3(init_top_pgt);
 	__flush_tlb_all();

 	/*
 	 * kasan_early_shadow_page has been used as early shadow memory, thus
 	 * it may contain some garbage. Now we can clear and write protect it,
 	 * since after the TLB flush no one should write to it.
 	 */
 	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 	for (i = 0; i < PTRS_PER_PTE; i++) {
 		pte_t pte;
 		pgprot_t prot;

 		prot = __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC);
 		pgprot_val(prot) &= __default_kernel_pte_mask;

 		pte = __pte(__pa(kasan_early_shadow_page) | pgprot_val(prot));
 		set_pte(&kasan_early_shadow_pte[i], pte);
 	}
 	/* Flush TLBs again to be sure that write protection applied. */
 	__flush_tlb_all();

 	init_task.kasan_depth = 0;
 	pr_info("KernelAddressSanitizer initialized\n");
 }
	// SPDX-License-Identifier: GPL-2.0
	#define DISABLE_BRANCH_PROFILING
	#define pr_fmt(fmt) "kasan: " fmt

	/* cpu_feature_enabled() cannot be used this early */
	#define USE_EARLY_PGTABLE_L5

	#include <linux/memblock.h>
	#include <linux/kasan.h>
	#include <linux/kdebug.h>
	#include <linux/mm.h>
	#include <linux/sched.h>
	#include <linux/sched/task.h>
	#include <linux/vmalloc.h>

	#include <asm/e820/types.h>
	#include <asm/pgalloc.h>
	#include <asm/tlbflush.h>
	#include <asm/sections.h>
	#include <asm/pgtable.h>
	#include <asm/cpu_entry_area.h>

	extern struct range pfn_mapped[E820_MAX_ENTRIES];

	static p4d_t tmp_p4d_table[MAX_PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);

	static __init void *early_alloc(size_t size, int nid, bool panic)
	{
	if (panic)
	return memblock_alloc_try_nid(size, size,
	__pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, nid);
	else
	return memblock_alloc_try_nid_nopanic(size, size,
	__pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, nid);
	}

	static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
	unsigned long end, int nid)
	{
	pte_t *pte;

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

	if (boot_cpu_has(X86_FEATURE_PSE) &&
	((end - addr) == PMD_SIZE) &&
	IS_ALIGNED(addr, PMD_SIZE)) {
	p = early_alloc(PMD_SIZE, nid, false);
	if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
	return;
	else if (p)
	memblock_free(__pa(p), PMD_SIZE);
	}

	p = early_alloc(PAGE_SIZE, nid, true);
	pmd_populate_kernel(&init_mm, pmd, p);
	}

	pte = pte_offset_kernel(pmd, addr);
	do {
	pte_t entry;
	void *p;

	if (!pte_none(*pte))
	continue;

	p = early_alloc(PAGE_SIZE, nid, true);
	entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
	set_pte_at(&init_mm, addr, pte, entry);
	} while (pte++, addr += PAGE_SIZE, addr != end);
	}

	static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
	unsigned long end, int nid)
	{
	pmd_t *pmd;
	unsigned long next;

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

	if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
	((end - addr) == PUD_SIZE) &&
	IS_ALIGNED(addr, PUD_SIZE)) {
	p = early_alloc(PUD_SIZE, nid, false);
	if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
	return;
	else if (p)
	memblock_free(__pa(p), PUD_SIZE);
	}

	p = early_alloc(PAGE_SIZE, nid, true);
	pud_populate(&init_mm, pud, p);
	}

	pmd = pmd_offset(pud, addr);
	do {
	next = pmd_addr_end(addr, end);
	if (!pmd_large(*pmd))
	kasan_populate_pmd(pmd, addr, next, nid);
	} while (pmd++, addr = next, addr != end);
	}

	static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
	unsigned long end, int nid)
	{
	pud_t *pud;
	unsigned long next;

	if (p4d_none(*p4d)) {
	void *p = early_alloc(PAGE_SIZE, nid, true);

	p4d_populate(&init_mm, p4d, p);
	}

	pud = pud_offset(p4d, addr);
	do {
	next = pud_addr_end(addr, end);
	if (!pud_large(*pud))
	kasan_populate_pud(pud, addr, next, nid);
	} while (pud++, addr = next, addr != end);
	}

	static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
	unsigned long end, int nid)
	{
	void *p;
	p4d_t *p4d;
	unsigned long next;

	if (pgd_none(*pgd)) {
	p = early_alloc(PAGE_SIZE, nid, true);
	pgd_populate(&init_mm, pgd, p);
	}

	p4d = p4d_offset(pgd, addr);
	do {
	next = p4d_addr_end(addr, end);
	kasan_populate_p4d(p4d, addr, next, nid);
	} while (p4d++, addr = next, addr != end);
	}

	static void __init kasan_populate_shadow(unsigned long addr, unsigned long end,
	int nid)
	{
	pgd_t *pgd;
	unsigned long next;

	addr = addr & PAGE_MASK;
	end = round_up(end, PAGE_SIZE);
	pgd = pgd_offset_k(addr);
	do {
	next = pgd_addr_end(addr, end);
	kasan_populate_pgd(pgd, addr, next, nid);
	} while (pgd++, addr = next, addr != end);
	}

	static void __init map_range(struct range *range)
	{
	unsigned long start;
	unsigned long end;

	start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
	end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));

	kasan_populate_shadow(start, end, early_pfn_to_nid(range->start));
	}

	static void __init clear_pgds(unsigned long start,
	unsigned long end)
	{
	pgd_t *pgd;
	/* See comment in kasan_init() */
	unsigned long pgd_end = end & PGDIR_MASK;

	for (; start < pgd_end; start += PGDIR_SIZE) {
	pgd = pgd_offset_k(start);
	/*
	* With folded p4d, pgd_clear() is nop, use p4d_clear()
	* instead.
	*/
	if (pgtable_l5_enabled())
	pgd_clear(pgd);
	else
	p4d_clear(p4d_offset(pgd, start));
	}

	pgd = pgd_offset_k(start);
	for (; start < end; start += P4D_SIZE)
	p4d_clear(p4d_offset(pgd, start));
	}

	static inline p4d_t early_p4d_offset(pgd_t pgd, unsigned long addr)
	{
	unsigned long p4d;

	if (!pgtable_l5_enabled())
	return (p4d_t *)pgd;

	p4d = __pa_nodebug(pgd_val(*pgd)) & PTE_PFN_MASK;
	p4d += __START_KERNEL_map - phys_base;
	return (p4d_t *)p4d + p4d_index(addr);
	}

	static void __init kasan_early_p4d_populate(pgd_t *pgd,
	unsigned long addr,
	unsigned long end)
	{
	pgd_t pgd_entry;
	p4d_t *p4d, p4d_entry;
	unsigned long next;

	if (pgd_none(*pgd)) {
	pgd_entry = __pgd(_KERNPG_TABLE \|
	__pa_nodebug(kasan_early_shadow_p4d));
	set_pgd(pgd, pgd_entry);
	}

	p4d = early_p4d_offset(pgd, addr);
	do {
	next = p4d_addr_end(addr, end);

	if (!p4d_none(*p4d))
	continue;

	p4d_entry = __p4d(_KERNPG_TABLE \|
	__pa_nodebug(kasan_early_shadow_pud));
	set_p4d(p4d, p4d_entry);
	} while (p4d++, addr = next, addr != end && p4d_none(*p4d));
	}

	static void __init kasan_map_early_shadow(pgd_t *pgd)
	{
	/* See comment in kasan_init() */
	unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
	unsigned long end = KASAN_SHADOW_END;
	unsigned long next;

	pgd += pgd_index(addr);
	do {
	next = pgd_addr_end(addr, end);
	kasan_early_p4d_populate(pgd, addr, next);
	} while (pgd++, addr = next, addr != end);
	}

	#ifdef CONFIG_KASAN_INLINE
	static int kasan_die_handler(struct notifier_block *self,
	unsigned long val,
	void *data)
	{
	if (val == DIE_GPF) {
	pr_emerg("CONFIG_KASAN_INLINE enabled\n");
	pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
	}
	return NOTIFY_OK;
	}

	static struct notifier_block kasan_die_notifier = {
	.notifier_call = kasan_die_handler,
	};
	#endif

	void __init kasan_early_init(void)
	{
	int i;
	pteval_t pte_val = __pa_nodebug(kasan_early_shadow_page) \|
	__PAGE_KERNEL \| _PAGE_ENC;
	pmdval_t pmd_val = __pa_nodebug(kasan_early_shadow_pte) \| _KERNPG_TABLE;
	pudval_t pud_val = __pa_nodebug(kasan_early_shadow_pmd) \| _KERNPG_TABLE;
	p4dval_t p4d_val = __pa_nodebug(kasan_early_shadow_pud) \| _KERNPG_TABLE;

	/* Mask out unsupported __PAGE_KERNEL bits: */
	pte_val &= __default_kernel_pte_mask;
	pmd_val &= __default_kernel_pte_mask;
	pud_val &= __default_kernel_pte_mask;
	p4d_val &= __default_kernel_pte_mask;

	for (i = 0; i < PTRS_PER_PTE; i++)
	kasan_early_shadow_pte[i] = __pte(pte_val);

	for (i = 0; i < PTRS_PER_PMD; i++)
	kasan_early_shadow_pmd[i] = __pmd(pmd_val);

	for (i = 0; i < PTRS_PER_PUD; i++)
	kasan_early_shadow_pud[i] = __pud(pud_val);

	for (i = 0; pgtable_l5_enabled() && i < PTRS_PER_P4D; i++)
	kasan_early_shadow_p4d[i] = __p4d(p4d_val);

	kasan_map_early_shadow(early_top_pgt);
	kasan_map_early_shadow(init_top_pgt);
	}

	void __init kasan_init(void)
	{
	int i;
	void shadow_cpu_entry_begin, shadow_cpu_entry_end;

	#ifdef CONFIG_KASAN_INLINE
	register_die_notifier(&kasan_die_notifier);
	#endif

	memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));

	/*
	* We use the same shadow offset for 4- and 5-level paging to
	* facilitate boot-time switching between paging modes.
	* As result in 5-level paging mode KASAN_SHADOW_START and
	* KASAN_SHADOW_END are not aligned to PGD boundary.
	*
	* KASAN_SHADOW_START doesn't share PGD with anything else.
	* We claim whole PGD entry to make things easier.
	*
	* KASAN_SHADOW_END lands in the last PGD entry and it collides with
	* bunch of things like kernel code, modules, EFI mapping, etc.
	* We need to take extra steps to not overwrite them.
	*/
	if (pgtable_l5_enabled()) {
	void *ptr;

	ptr = (void )pgd_page_vaddr(pgd_offset_k(KASAN_SHADOW_END));
	memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
	set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
	__pgd(__pa(tmp_p4d_table) \| _KERNPG_TABLE));
	}

	load_cr3(early_top_pgt);
	__flush_tlb_all();

	clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);

	kasan_populate_early_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
	kasan_mem_to_shadow((void *)PAGE_OFFSET));

	for (i = 0; i < E820_MAX_ENTRIES; i++) {
	if (pfn_mapped[i].end == 0)
	break;

	map_range(&pfn_mapped[i]);
	}

	shadow_cpu_entry_begin = (void *)CPU_ENTRY_AREA_BASE;
	shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
	shadow_cpu_entry_begin = (void *)round_down(
	(unsigned long)shadow_cpu_entry_begin, PAGE_SIZE);

	shadow_cpu_entry_end = (void *)(CPU_ENTRY_AREA_BASE +
	CPU_ENTRY_AREA_MAP_SIZE);
	shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
	shadow_cpu_entry_end = (void *)round_up(
	(unsigned long)shadow_cpu_entry_end, PAGE_SIZE);

	kasan_populate_early_shadow(
	kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
	shadow_cpu_entry_begin);

	kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
	(unsigned long)shadow_cpu_entry_end, 0);

	kasan_populate_early_shadow(shadow_cpu_entry_end,
	kasan_mem_to_shadow((void *)__START_KERNEL_map));

	kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
	(unsigned long)kasan_mem_to_shadow(_end),
	early_pfn_to_nid(__pa(_stext)));

	kasan_populate_early_shadow(kasan_mem_to_shadow((void *)MODULES_END),
	(void *)KASAN_SHADOW_END);

	load_cr3(init_top_pgt);
	__flush_tlb_all();

	/*
	* kasan_early_shadow_page has been used as early shadow memory, thus
	* it may contain some garbage. Now we can clear and write protect it,
	* since after the TLB flush no one should write to it.
	*/
	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
	for (i = 0; i < PTRS_PER_PTE; i++) {
	pte_t pte;
	pgprot_t prot;

	prot = __pgprot(__PAGE_KERNEL_RO \| _PAGE_ENC);
	pgprot_val(prot) &= __default_kernel_pte_mask;

	pte = __pte(__pa(kasan_early_shadow_page) \| pgprot_val(prot));
	set_pte(&kasan_early_shadow_pte[i], pte);
	}
	/* Flush TLBs again to be sure that write protection applied. */
	__flush_tlb_all();

	init_task.kasan_depth = 0;
	pr_info("KernelAddressSanitizer initialized\n");
	}