arch/riscv/mm/pageattr.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2019 SiFive
  */

 #include <linux/pagewalk.h>
 #include <linux/pgtable.h>
 #include <linux/vmalloc.h>
 #include <asm/tlbflush.h>
 #include <asm/bitops.h>
 #include <asm/set_memory.h>

 struct pageattr_masks {
 	pgprot_t set_mask;
 	pgprot_t clear_mask;
 };

 static unsigned long set_pageattr_masks(unsigned long val, struct mm_walk *walk)
 {
 	struct pageattr_masks *masks = walk->private;
 	unsigned long new_val = val;

 	new_val &= ~(pgprot_val(masks->clear_mask));
 	new_val |= (pgprot_val(masks->set_mask));

 	return new_val;
 }

 static int pageattr_p4d_entry(p4d_t *p4d, unsigned long addr,
 			      unsigned long next, struct mm_walk *walk)
 {
 	p4d_t val = p4dp_get(p4d);

 	if (p4d_leaf(val)) {
 		val = __p4d(set_pageattr_masks(p4d_val(val), walk));
 		set_p4d(p4d, val);
 	}

 	return 0;
 }

 static int pageattr_pud_entry(pud_t *pud, unsigned long addr,
 			      unsigned long next, struct mm_walk *walk)
 {
 	pud_t val = pudp_get(pud);

 	if (pud_leaf(val)) {
 		val = __pud(set_pageattr_masks(pud_val(val), walk));
 		set_pud(pud, val);
 	}

 	return 0;
 }

 static int pageattr_pmd_entry(pmd_t *pmd, unsigned long addr,
 			      unsigned long next, struct mm_walk *walk)
 {
 	pmd_t val = pmdp_get(pmd);

 	if (pmd_leaf(val)) {
 		val = __pmd(set_pageattr_masks(pmd_val(val), walk));
 		set_pmd(pmd, val);
 	}

 	return 0;
 }

 static int pageattr_pte_entry(pte_t *pte, unsigned long addr,
 			      unsigned long next, struct mm_walk *walk)
 {
 	pte_t val = ptep_get(pte);

 	val = __pte(set_pageattr_masks(pte_val(val), walk));
 	set_pte(pte, val);

 	return 0;
 }

 static int pageattr_pte_hole(unsigned long addr, unsigned long next,
 			     int depth, struct mm_walk *walk)
 {
 	/* Nothing to do here */
 	return 0;
 }

 static const struct mm_walk_ops pageattr_ops = {
 	.p4d_entry = pageattr_p4d_entry,
 	.pud_entry = pageattr_pud_entry,
 	.pmd_entry = pageattr_pmd_entry,
 	.pte_entry = pageattr_pte_entry,
 	.pte_hole = pageattr_pte_hole,
 	.walk_lock = PGWALK_RDLOCK,
 };

 #ifdef CONFIG_64BIT
 static int __split_linear_mapping_pmd(pud_t *pudp,
 				      unsigned long vaddr, unsigned long end)
 {
 	pmd_t *pmdp;
 	unsigned long next;

 	pmdp = pmd_offset(pudp, vaddr);

 	do {
 		next = pmd_addr_end(vaddr, end);

 		if (next - vaddr >= PMD_SIZE &&
 		    vaddr <= (vaddr & PMD_MASK) && end >= next)
 			continue;

 		if (pmd_leaf(pmdp_get(pmdp))) {
 			struct page *pte_page;
 			unsigned long pfn = _pmd_pfn(pmdp_get(pmdp));
 			pgprot_t prot = __pgprot(pmd_val(pmdp_get(pmdp)) & ~_PAGE_PFN_MASK);
 			pte_t *ptep_new;
 			int i;

 			pte_page = alloc_page(GFP_KERNEL);
 			if (!pte_page)
 				return -ENOMEM;

 			ptep_new = (pte_t *)page_address(pte_page);
 			for (i = 0; i < PTRS_PER_PTE; ++i, ++ptep_new)
 				set_pte(ptep_new, pfn_pte(pfn + i, prot));

 			smp_wmb();

 			set_pmd(pmdp, pfn_pmd(page_to_pfn(pte_page), PAGE_TABLE));
 		}
 	} while (pmdp++, vaddr = next, vaddr != end);

 	return 0;
 }

 static int __split_linear_mapping_pud(p4d_t *p4dp,
 				      unsigned long vaddr, unsigned long end)
 {
 	pud_t *pudp;
 	unsigned long next;
 	int ret;

 	pudp = pud_offset(p4dp, vaddr);

 	do {
 		next = pud_addr_end(vaddr, end);

 		if (next - vaddr >= PUD_SIZE &&
 		    vaddr <= (vaddr & PUD_MASK) && end >= next)
 			continue;

 		if (pud_leaf(pudp_get(pudp))) {
 			struct page *pmd_page;
 			unsigned long pfn = _pud_pfn(pudp_get(pudp));
 			pgprot_t prot = __pgprot(pud_val(pudp_get(pudp)) & ~_PAGE_PFN_MASK);
 			pmd_t *pmdp_new;
 			int i;

 			pmd_page = alloc_page(GFP_KERNEL);
 			if (!pmd_page)
 				return -ENOMEM;

 			pmdp_new = (pmd_t *)page_address(pmd_page);
 			for (i = 0; i < PTRS_PER_PMD; ++i, ++pmdp_new)
 				set_pmd(pmdp_new,
 					pfn_pmd(pfn + ((i * PMD_SIZE) >> PAGE_SHIFT), prot));

 			smp_wmb();

 			set_pud(pudp, pfn_pud(page_to_pfn(pmd_page), PAGE_TABLE));
 		}

 		ret = __split_linear_mapping_pmd(pudp, vaddr, next);
 		if (ret)
 			return ret;
 	} while (pudp++, vaddr = next, vaddr != end);

 	return 0;
 }

 static int __split_linear_mapping_p4d(pgd_t *pgdp,
 				      unsigned long vaddr, unsigned long end)
 {
 	p4d_t *p4dp;
 	unsigned long next;
 	int ret;

 	p4dp = p4d_offset(pgdp, vaddr);

 	do {
 		next = p4d_addr_end(vaddr, end);

 		/*
 		 * If [vaddr; end] contains [vaddr & P4D_MASK; next], we don't
 		 * need to split, we'll change the protections on the whole P4D.
 		 */
 		if (next - vaddr >= P4D_SIZE &&
 		    vaddr <= (vaddr & P4D_MASK) && end >= next)
 			continue;

 		if (p4d_leaf(p4dp_get(p4dp))) {
 			struct page *pud_page;
 			unsigned long pfn = _p4d_pfn(p4dp_get(p4dp));
 			pgprot_t prot = __pgprot(p4d_val(p4dp_get(p4dp)) & ~_PAGE_PFN_MASK);
 			pud_t *pudp_new;
 			int i;

 			pud_page = alloc_page(GFP_KERNEL);
 			if (!pud_page)
 				return -ENOMEM;

 			/*
 			 * Fill the pud level with leaf puds that have the same
 			 * protections as the leaf p4d.
 			 */
 			pudp_new = (pud_t *)page_address(pud_page);
 			for (i = 0; i < PTRS_PER_PUD; ++i, ++pudp_new)
 				set_pud(pudp_new,
 					pfn_pud(pfn + ((i * PUD_SIZE) >> PAGE_SHIFT), prot));

 			/*
 			 * Make sure the pud filling is not reordered with the
 			 * p4d store which could result in seeing a partially
 			 * filled pud level.
 			 */
 			smp_wmb();

 			set_p4d(p4dp, pfn_p4d(page_to_pfn(pud_page), PAGE_TABLE));
 		}

 		ret = __split_linear_mapping_pud(p4dp, vaddr, next);
 		if (ret)
 			return ret;
 	} while (p4dp++, vaddr = next, vaddr != end);

 	return 0;
 }

 static int __split_linear_mapping_pgd(pgd_t *pgdp,
 				      unsigned long vaddr,
 				      unsigned long end)
 {
 	unsigned long next;
 	int ret;

 	do {
 		next = pgd_addr_end(vaddr, end);
 		/* We never use PGD mappings for the linear mapping */
 		ret = __split_linear_mapping_p4d(pgdp, vaddr, next);
 		if (ret)
 			return ret;
 	} while (pgdp++, vaddr = next, vaddr != end);

 	return 0;
 }

 static int split_linear_mapping(unsigned long start, unsigned long end)
 {
 	return __split_linear_mapping_pgd(pgd_offset_k(start), start, end);
 }
 #endif	/* CONFIG_64BIT */

 static int __set_memory(unsigned long addr, int numpages, pgprot_t set_mask,
 			pgprot_t clear_mask)
 {
 	int ret;
 	unsigned long start = addr;
 	unsigned long end = start + PAGE_SIZE * numpages;
 	unsigned long __maybe_unused lm_start;
 	unsigned long __maybe_unused lm_end;
 	struct pageattr_masks masks = {
 		.set_mask = set_mask,
 		.clear_mask = clear_mask
 	};

 	if (!numpages)
 		return 0;

 	mmap_write_lock(&init_mm);

 #ifdef CONFIG_64BIT
 	/*
 	 * We are about to change the permissions of a kernel mapping, we must
 	 * apply the same changes to its linear mapping alias, which may imply
 	 * splitting a huge mapping.
 	 */

 	if (is_vmalloc_or_module_addr((void *)start)) {
 		struct vm_struct *area = NULL;
 		int i, page_start;

 		area = find_vm_area((void *)start);
 		page_start = (start - (unsigned long)area->addr) >> PAGE_SHIFT;

 		for (i = page_start; i < page_start + numpages; ++i) {
 			lm_start = (unsigned long)page_address(area->pages[i]);
 			lm_end = lm_start + PAGE_SIZE;

 			ret = split_linear_mapping(lm_start, lm_end);
 			if (ret)
 				goto unlock;

 			ret = walk_page_range_novma(&init_mm, lm_start, lm_end,
 						    &pageattr_ops, NULL, &masks);
 			if (ret)
 				goto unlock;
 		}
 	} else if (is_kernel_mapping(start) || is_linear_mapping(start)) {
 		if (is_kernel_mapping(start)) {
 			lm_start = (unsigned long)lm_alias(start);
 			lm_end = (unsigned long)lm_alias(end);
 		} else {
 			lm_start = start;
 			lm_end = end;
 		}

 		ret = split_linear_mapping(lm_start, lm_end);
 		if (ret)
 			goto unlock;

 		ret = walk_page_range_novma(&init_mm, lm_start, lm_end,
 					    &pageattr_ops, NULL, &masks);
 		if (ret)
 			goto unlock;
 	}

 	ret =  walk_page_range_novma(&init_mm, start, end, &pageattr_ops, NULL,
 				     &masks);

 unlock:
 	mmap_write_unlock(&init_mm);

 	/*
 	 * We can't use flush_tlb_kernel_range() here as we may have split a
 	 * hugepage that is larger than that, so let's flush everything.
 	 */
 	flush_tlb_all();
 #else
 	ret =  walk_page_range_novma(&init_mm, start, end, &pageattr_ops, NULL,
 				     &masks);

 	mmap_write_unlock(&init_mm);

 	flush_tlb_kernel_range(start, end);
 #endif

 	return ret;
 }

 int set_memory_rw_nx(unsigned long addr, int numpages)
 {
 	return __set_memory(addr, numpages, __pgprot(_PAGE_READ | _PAGE_WRITE),
 			    __pgprot(_PAGE_EXEC));
 }

 int set_memory_ro(unsigned long addr, int numpages)
 {
 	return __set_memory(addr, numpages, __pgprot(_PAGE_READ),
 			    __pgprot(_PAGE_WRITE));
 }

 int set_memory_rw(unsigned long addr, int numpages)
 {
 	return __set_memory(addr, numpages, __pgprot(_PAGE_READ | _PAGE_WRITE),
 			    __pgprot(0));
 }

 int set_memory_x(unsigned long addr, int numpages)
 {
 	return __set_memory(addr, numpages, __pgprot(_PAGE_EXEC), __pgprot(0));
 }

 int set_memory_nx(unsigned long addr, int numpages)
 {
 	return __set_memory(addr, numpages, __pgprot(0), __pgprot(_PAGE_EXEC));
 }

 int set_direct_map_invalid_noflush(struct page *page)
 {
 	return __set_memory((unsigned long)page_address(page), 1,
 			    __pgprot(0), __pgprot(_PAGE_PRESENT));
 }

 int set_direct_map_default_noflush(struct page *page)
 {
 	return __set_memory((unsigned long)page_address(page), 1,
 			    PAGE_KERNEL, __pgprot(_PAGE_EXEC));
 }

 int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid)
 {
 	pgprot_t set, clear;

 	if (valid) {
 		set = PAGE_KERNEL;
 		clear = __pgprot(_PAGE_EXEC);
 	} else {
 		set = __pgprot(0);
 		clear = __pgprot(_PAGE_PRESENT);
 	}

 	return __set_memory((unsigned long)page_address(page), nr, set, clear);
 }

 #ifdef CONFIG_DEBUG_PAGEALLOC
 static int debug_pagealloc_set_page(pte_t *pte, unsigned long addr, void *data)
 {
 	int enable = *(int *)data;

 	unsigned long val = pte_val(ptep_get(pte));

 	if (enable)
 		val |= _PAGE_PRESENT;
 	else
 		val &= ~_PAGE_PRESENT;

 	set_pte(pte, __pte(val));

 	return 0;
 }

 void __kernel_map_pages(struct page *page, int numpages, int enable)
 {
 	if (!debug_pagealloc_enabled())
 		return;

 	unsigned long start = (unsigned long)page_address(page);
 	unsigned long size = PAGE_SIZE * numpages;

 	apply_to_existing_page_range(&init_mm, start, size, debug_pagealloc_set_page, &enable);

 	flush_tlb_kernel_range(start, start + size);
 }
 #endif

 bool kernel_page_present(struct page *page)
 {
 	unsigned long addr = (unsigned long)page_address(page);
 	pgd_t *pgd;
 	pud_t *pud;
 	p4d_t *p4d;
 	pmd_t *pmd;
 	pte_t *pte;

 	pgd = pgd_offset_k(addr);
 	if (!pgd_present(pgdp_get(pgd)))
 		return false;
 	if (pgd_leaf(pgdp_get(pgd)))
 		return true;

 	p4d = p4d_offset(pgd, addr);
 	if (!p4d_present(p4dp_get(p4d)))
 		return false;
 	if (p4d_leaf(p4dp_get(p4d)))
 		return true;

 	pud = pud_offset(p4d, addr);
 	if (!pud_present(pudp_get(pud)))
 		return false;
 	if (pud_leaf(pudp_get(pud)))
 		return true;

 	pmd = pmd_offset(pud, addr);
 	if (!pmd_present(pmdp_get(pmd)))
 		return false;
 	if (pmd_leaf(pmdp_get(pmd)))
 		return true;

 	pte = pte_offset_kernel(pmd, addr);
 	return pte_present(ptep_get(pte));
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (C) 2019 SiFive
	*/

	#include <linux/pagewalk.h>
	#include <linux/pgtable.h>
	#include <linux/vmalloc.h>
	#include <asm/tlbflush.h>
	#include <asm/bitops.h>
	#include <asm/set_memory.h>

	struct pageattr_masks {
	pgprot_t set_mask;
	pgprot_t clear_mask;
	};

	static unsigned long set_pageattr_masks(unsigned long val, struct mm_walk *walk)
	{
	struct pageattr_masks *masks = walk->private;
	unsigned long new_val = val;

	new_val &= ~(pgprot_val(masks->clear_mask));
	new_val \|= (pgprot_val(masks->set_mask));

	return new_val;
	}

	static int pageattr_p4d_entry(p4d_t *p4d, unsigned long addr,
	unsigned long next, struct mm_walk *walk)
	{
	p4d_t val = p4dp_get(p4d);

	if (p4d_leaf(val)) {
	val = __p4d(set_pageattr_masks(p4d_val(val), walk));
	set_p4d(p4d, val);
	}

	return 0;
	}

	static int pageattr_pud_entry(pud_t *pud, unsigned long addr,
	unsigned long next, struct mm_walk *walk)
	{
	pud_t val = pudp_get(pud);

	if (pud_leaf(val)) {
	val = __pud(set_pageattr_masks(pud_val(val), walk));
	set_pud(pud, val);
	}

	return 0;
	}

	static int pageattr_pmd_entry(pmd_t *pmd, unsigned long addr,
	unsigned long next, struct mm_walk *walk)
	{
	pmd_t val = pmdp_get(pmd);

	if (pmd_leaf(val)) {
	val = __pmd(set_pageattr_masks(pmd_val(val), walk));
	set_pmd(pmd, val);
	}

	return 0;
	}

	static int pageattr_pte_entry(pte_t *pte, unsigned long addr,
	unsigned long next, struct mm_walk *walk)
	{
	pte_t val = ptep_get(pte);

	val = __pte(set_pageattr_masks(pte_val(val), walk));
	set_pte(pte, val);

	return 0;
	}

	static int pageattr_pte_hole(unsigned long addr, unsigned long next,
	int depth, struct mm_walk *walk)
	{
	/* Nothing to do here */
	return 0;
	}

	static const struct mm_walk_ops pageattr_ops = {
	.p4d_entry = pageattr_p4d_entry,
	.pud_entry = pageattr_pud_entry,
	.pmd_entry = pageattr_pmd_entry,
	.pte_entry = pageattr_pte_entry,
	.pte_hole = pageattr_pte_hole,
	.walk_lock = PGWALK_RDLOCK,
	};

	#ifdef CONFIG_64BIT
	static int __split_linear_mapping_pmd(pud_t *pudp,
	unsigned long vaddr, unsigned long end)
	{
	pmd_t *pmdp;
	unsigned long next;

	pmdp = pmd_offset(pudp, vaddr);

	do {
	next = pmd_addr_end(vaddr, end);

	if (next - vaddr >= PMD_SIZE &&
	vaddr <= (vaddr & PMD_MASK) && end >= next)
	continue;

	if (pmd_leaf(pmdp_get(pmdp))) {
	struct page *pte_page;
	unsigned long pfn = _pmd_pfn(pmdp_get(pmdp));
	pgprot_t prot = __pgprot(pmd_val(pmdp_get(pmdp)) & ~_PAGE_PFN_MASK);
	pte_t *ptep_new;
	int i;

	pte_page = alloc_page(GFP_KERNEL);
	if (!pte_page)
	return -ENOMEM;

	ptep_new = (pte_t *)page_address(pte_page);
	for (i = 0; i < PTRS_PER_PTE; ++i, ++ptep_new)
	set_pte(ptep_new, pfn_pte(pfn + i, prot));

	smp_wmb();

	set_pmd(pmdp, pfn_pmd(page_to_pfn(pte_page), PAGE_TABLE));
	}
	} while (pmdp++, vaddr = next, vaddr != end);

	return 0;
	}

	static int __split_linear_mapping_pud(p4d_t *p4dp,
	unsigned long vaddr, unsigned long end)
	{
	pud_t *pudp;
	unsigned long next;
	int ret;

	pudp = pud_offset(p4dp, vaddr);

	do {
	next = pud_addr_end(vaddr, end);

	if (next - vaddr >= PUD_SIZE &&
	vaddr <= (vaddr & PUD_MASK) && end >= next)
	continue;

	if (pud_leaf(pudp_get(pudp))) {
	struct page *pmd_page;
	unsigned long pfn = _pud_pfn(pudp_get(pudp));
	pgprot_t prot = __pgprot(pud_val(pudp_get(pudp)) & ~_PAGE_PFN_MASK);
	pmd_t *pmdp_new;
	int i;

	pmd_page = alloc_page(GFP_KERNEL);
	if (!pmd_page)
	return -ENOMEM;

	pmdp_new = (pmd_t *)page_address(pmd_page);
	for (i = 0; i < PTRS_PER_PMD; ++i, ++pmdp_new)
	set_pmd(pmdp_new,
	pfn_pmd(pfn + ((i * PMD_SIZE) >> PAGE_SHIFT), prot));

	smp_wmb();

	set_pud(pudp, pfn_pud(page_to_pfn(pmd_page), PAGE_TABLE));
	}

	ret = __split_linear_mapping_pmd(pudp, vaddr, next);
	if (ret)
	return ret;
	} while (pudp++, vaddr = next, vaddr != end);

	return 0;
	}

	static int __split_linear_mapping_p4d(pgd_t *pgdp,
	unsigned long vaddr, unsigned long end)
	{
	p4d_t *p4dp;
	unsigned long next;
	int ret;

	p4dp = p4d_offset(pgdp, vaddr);

	do {
	next = p4d_addr_end(vaddr, end);

	/*
	* If [vaddr; end] contains [vaddr & P4D_MASK; next], we don't
	* need to split, we'll change the protections on the whole P4D.
	*/
	if (next - vaddr >= P4D_SIZE &&
	vaddr <= (vaddr & P4D_MASK) && end >= next)
	continue;

	if (p4d_leaf(p4dp_get(p4dp))) {
	struct page *pud_page;
	unsigned long pfn = _p4d_pfn(p4dp_get(p4dp));
	pgprot_t prot = __pgprot(p4d_val(p4dp_get(p4dp)) & ~_PAGE_PFN_MASK);
	pud_t *pudp_new;
	int i;

	pud_page = alloc_page(GFP_KERNEL);
	if (!pud_page)
	return -ENOMEM;

	/*
	* Fill the pud level with leaf puds that have the same
	* protections as the leaf p4d.
	*/
	pudp_new = (pud_t *)page_address(pud_page);
	for (i = 0; i < PTRS_PER_PUD; ++i, ++pudp_new)
	set_pud(pudp_new,
	pfn_pud(pfn + ((i * PUD_SIZE) >> PAGE_SHIFT), prot));

	/*
	* Make sure the pud filling is not reordered with the
	* p4d store which could result in seeing a partially
	* filled pud level.
	*/
	smp_wmb();

	set_p4d(p4dp, pfn_p4d(page_to_pfn(pud_page), PAGE_TABLE));
	}

	ret = __split_linear_mapping_pud(p4dp, vaddr, next);
	if (ret)
	return ret;
	} while (p4dp++, vaddr = next, vaddr != end);

	return 0;
	}

	static int __split_linear_mapping_pgd(pgd_t *pgdp,
	unsigned long vaddr,
	unsigned long end)
	{
	unsigned long next;
	int ret;

	do {
	next = pgd_addr_end(vaddr, end);
	/* We never use PGD mappings for the linear mapping */
	ret = __split_linear_mapping_p4d(pgdp, vaddr, next);
	if (ret)
	return ret;
	} while (pgdp++, vaddr = next, vaddr != end);

	return 0;
	}

	static int split_linear_mapping(unsigned long start, unsigned long end)
	{
	return __split_linear_mapping_pgd(pgd_offset_k(start), start, end);
	}
	#endif /* CONFIG_64BIT */

	static int __set_memory(unsigned long addr, int numpages, pgprot_t set_mask,
	pgprot_t clear_mask)
	{
	int ret;
	unsigned long start = addr;
	unsigned long end = start + PAGE_SIZE * numpages;
	unsigned long __maybe_unused lm_start;
	unsigned long __maybe_unused lm_end;
	struct pageattr_masks masks = {
	.set_mask = set_mask,
	.clear_mask = clear_mask
	};

	if (!numpages)
	return 0;

	mmap_write_lock(&init_mm);

	#ifdef CONFIG_64BIT
	/*
	* We are about to change the permissions of a kernel mapping, we must
	* apply the same changes to its linear mapping alias, which may imply
	* splitting a huge mapping.
	*/

	if (is_vmalloc_or_module_addr((void *)start)) {
	struct vm_struct *area = NULL;
	int i, page_start;

	area = find_vm_area((void *)start);
	page_start = (start - (unsigned long)area->addr) >> PAGE_SHIFT;

	for (i = page_start; i < page_start + numpages; ++i) {
	lm_start = (unsigned long)page_address(area->pages[i]);
	lm_end = lm_start + PAGE_SIZE;

	ret = split_linear_mapping(lm_start, lm_end);
	if (ret)
	goto unlock;

	ret = walk_page_range_novma(&init_mm, lm_start, lm_end,
	&pageattr_ops, NULL, &masks);
	if (ret)
	goto unlock;
	}
	} else if (is_kernel_mapping(start) \|\| is_linear_mapping(start)) {
	if (is_kernel_mapping(start)) {
	lm_start = (unsigned long)lm_alias(start);
	lm_end = (unsigned long)lm_alias(end);
	} else {
	lm_start = start;
	lm_end = end;
	}

	ret = split_linear_mapping(lm_start, lm_end);
	if (ret)
	goto unlock;

	ret = walk_page_range_novma(&init_mm, lm_start, lm_end,
	&pageattr_ops, NULL, &masks);
	if (ret)
	goto unlock;
	}

	ret = walk_page_range_novma(&init_mm, start, end, &pageattr_ops, NULL,
	&masks);

	unlock:
	mmap_write_unlock(&init_mm);

	/*
	* We can't use flush_tlb_kernel_range() here as we may have split a
	* hugepage that is larger than that, so let's flush everything.
	*/
	flush_tlb_all();
	#else
	ret = walk_page_range_novma(&init_mm, start, end, &pageattr_ops, NULL,
	&masks);

	mmap_write_unlock(&init_mm);

	flush_tlb_kernel_range(start, end);
	#endif

	return ret;
	}

	int set_memory_rw_nx(unsigned long addr, int numpages)
	{
	return __set_memory(addr, numpages, __pgprot(_PAGE_READ \| _PAGE_WRITE),
	__pgprot(_PAGE_EXEC));
	}

	int set_memory_ro(unsigned long addr, int numpages)
	{
	return __set_memory(addr, numpages, __pgprot(_PAGE_READ),
	__pgprot(_PAGE_WRITE));
	}

	int set_memory_rw(unsigned long addr, int numpages)
	{
	return __set_memory(addr, numpages, __pgprot(_PAGE_READ \| _PAGE_WRITE),
	__pgprot(0));
	}

	int set_memory_x(unsigned long addr, int numpages)
	{
	return __set_memory(addr, numpages, __pgprot(_PAGE_EXEC), __pgprot(0));
	}

	int set_memory_nx(unsigned long addr, int numpages)
	{
	return __set_memory(addr, numpages, __pgprot(0), __pgprot(_PAGE_EXEC));
	}

	int set_direct_map_invalid_noflush(struct page *page)
	{
	return __set_memory((unsigned long)page_address(page), 1,
	__pgprot(0), __pgprot(_PAGE_PRESENT));
	}

	int set_direct_map_default_noflush(struct page *page)
	{
	return __set_memory((unsigned long)page_address(page), 1,
	PAGE_KERNEL, __pgprot(_PAGE_EXEC));
	}

	int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid)
	{
	pgprot_t set, clear;

	if (valid) {
	set = PAGE_KERNEL;
	clear = __pgprot(_PAGE_EXEC);
	} else {
	set = __pgprot(0);
	clear = __pgprot(_PAGE_PRESENT);
	}

	return __set_memory((unsigned long)page_address(page), nr, set, clear);
	}

	#ifdef CONFIG_DEBUG_PAGEALLOC
	static int debug_pagealloc_set_page(pte_t pte, unsigned long addr, void data)
	{
	int enable = (int )data;

	unsigned long val = pte_val(ptep_get(pte));

	if (enable)
	val \|= _PAGE_PRESENT;
	else
	val &= ~_PAGE_PRESENT;

	set_pte(pte, __pte(val));

	return 0;
	}

	void __kernel_map_pages(struct page *page, int numpages, int enable)
	{
	if (!debug_pagealloc_enabled())
	return;

	unsigned long start = (unsigned long)page_address(page);
	unsigned long size = PAGE_SIZE * numpages;

	apply_to_existing_page_range(&init_mm, start, size, debug_pagealloc_set_page, &enable);

	flush_tlb_kernel_range(start, start + size);
	}
	#endif

	bool kernel_page_present(struct page *page)
	{
	unsigned long addr = (unsigned long)page_address(page);
	pgd_t *pgd;
	pud_t *pud;
	p4d_t *p4d;
	pmd_t *pmd;
	pte_t *pte;

	pgd = pgd_offset_k(addr);
	if (!pgd_present(pgdp_get(pgd)))
	return false;
	if (pgd_leaf(pgdp_get(pgd)))
	return true;

	p4d = p4d_offset(pgd, addr);
	if (!p4d_present(p4dp_get(p4d)))
	return false;
	if (p4d_leaf(p4dp_get(p4d)))
	return true;

	pud = pud_offset(p4d, addr);
	if (!pud_present(pudp_get(pud)))
	return false;
	if (pud_leaf(pudp_get(pud)))
	return true;

	pmd = pmd_offset(pud, addr);
	if (!pmd_present(pmdp_get(pmd)))
	return false;
	if (pmd_leaf(pmdp_get(pmd)))
	return true;

	pte = pte_offset_kernel(pmd, addr);
	return pte_present(ptep_get(pte));
	}