arch/s390/mm/pageattr.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright IBM Corp. 2011
  * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
  */
 #include <linux/hugetlb.h>
 #include <linux/proc_fs.h>
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
 #include <asm/cacheflush.h>
 #include <asm/facility.h>
 #include <asm/pgalloc.h>
 #include <asm/kfence.h>
 #include <asm/page.h>
 #include <asm/set_memory.h>

 static inline unsigned long sske_frame(unsigned long addr, unsigned char skey)
 {
 	asm volatile(".insn rrf,0xb22b0000,%[skey],%[addr],1,0"
 		     : [addr] "+a" (addr) : [skey] "d" (skey));
 	return addr;
 }

 void __storage_key_init_range(unsigned long start, unsigned long end)
 {
 	unsigned long boundary, size;

 	while (start < end) {
 		if (MACHINE_HAS_EDAT1) {
 			/* set storage keys for a 1MB frame */
 			size = 1UL << 20;
 			boundary = (start + size) & ~(size - 1);
 			if (boundary <= end) {
 				do {
 					start = sske_frame(start, PAGE_DEFAULT_KEY);
 				} while (start < boundary);
 				continue;
 			}
 		}
 		page_set_storage_key(start, PAGE_DEFAULT_KEY, 1);
 		start += PAGE_SIZE;
 	}
 }

 #ifdef CONFIG_PROC_FS
 atomic_long_t __bootdata_preserved(direct_pages_count[PG_DIRECT_MAP_MAX]);

 void arch_report_meminfo(struct seq_file *m)
 {
 	seq_printf(m, "DirectMap4k:    %8lu kB\n",
 		   atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_4K]) << 2);
 	seq_printf(m, "DirectMap1M:    %8lu kB\n",
 		   atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_1M]) << 10);
 	seq_printf(m, "DirectMap2G:    %8lu kB\n",
 		   atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_2G]) << 21);
 }
 #endif /* CONFIG_PROC_FS */

 static void pgt_set(unsigned long *old, unsigned long new, unsigned long addr,
 		    unsigned long dtt)
 {
 	unsigned long *table, mask;

 	mask = 0;
 	if (MACHINE_HAS_EDAT2) {
 		switch (dtt) {
 		case CRDTE_DTT_REGION3:
 			mask = ~(PTRS_PER_PUD * sizeof(pud_t) - 1);
 			break;
 		case CRDTE_DTT_SEGMENT:
 			mask = ~(PTRS_PER_PMD * sizeof(pmd_t) - 1);
 			break;
 		case CRDTE_DTT_PAGE:
 			mask = ~(PTRS_PER_PTE * sizeof(pte_t) - 1);
 			break;
 		}
 		table = (unsigned long *)((unsigned long)old & mask);
 		crdte(*old, new, table, dtt, addr, S390_lowcore.kernel_asce.val);
 	} else if (MACHINE_HAS_IDTE) {
 		cspg(old, *old, new);
 	} else {
 		csp((unsigned int *)old + 1, *old, new);
 	}
 }

 static int walk_pte_level(pmd_t *pmdp, unsigned long addr, unsigned long end,
 			  unsigned long flags)
 {
 	pte_t *ptep, new;

 	if (flags == SET_MEMORY_4K)
 		return 0;
 	ptep = pte_offset_kernel(pmdp, addr);
 	do {
 		new = *ptep;
 		if (pte_none(new))
 			return -EINVAL;
 		if (flags & SET_MEMORY_RO)
 			new = pte_wrprotect(new);
 		else if (flags & SET_MEMORY_RW)
 			new = pte_mkwrite_novma(pte_mkdirty(new));
 		if (flags & SET_MEMORY_NX)
 			new = set_pte_bit(new, __pgprot(_PAGE_NOEXEC));
 		else if (flags & SET_MEMORY_X)
 			new = clear_pte_bit(new, __pgprot(_PAGE_NOEXEC));
 		if (flags & SET_MEMORY_INV) {
 			new = set_pte_bit(new, __pgprot(_PAGE_INVALID));
 		} else if (flags & SET_MEMORY_DEF) {
 			new = __pte(pte_val(new) & PAGE_MASK);
 			new = set_pte_bit(new, PAGE_KERNEL);
 			if (!MACHINE_HAS_NX)
 				new = clear_pte_bit(new, __pgprot(_PAGE_NOEXEC));
 		}
 		pgt_set((unsigned long *)ptep, pte_val(new), addr, CRDTE_DTT_PAGE);
 		ptep++;
 		addr += PAGE_SIZE;
 		cond_resched();
 	} while (addr < end);
 	return 0;
 }

 static int split_pmd_page(pmd_t *pmdp, unsigned long addr)
 {
 	unsigned long pte_addr, prot;
 	pte_t *pt_dir, *ptep;
 	pmd_t new;
 	int i, ro, nx;

 	pt_dir = vmem_pte_alloc();
 	if (!pt_dir)
 		return -ENOMEM;
 	pte_addr = pmd_pfn(*pmdp) << PAGE_SHIFT;
 	ro = !!(pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT);
 	nx = !!(pmd_val(*pmdp) & _SEGMENT_ENTRY_NOEXEC);
 	prot = pgprot_val(ro ? PAGE_KERNEL_RO : PAGE_KERNEL);
 	if (!nx)
 		prot &= ~_PAGE_NOEXEC;
 	ptep = pt_dir;
 	for (i = 0; i < PTRS_PER_PTE; i++) {
 		set_pte(ptep, __pte(pte_addr | prot));
 		pte_addr += PAGE_SIZE;
 		ptep++;
 	}
 	new = __pmd(__pa(pt_dir) | _SEGMENT_ENTRY);
 	pgt_set((unsigned long *)pmdp, pmd_val(new), addr, CRDTE_DTT_SEGMENT);
 	update_page_count(PG_DIRECT_MAP_4K, PTRS_PER_PTE);
 	update_page_count(PG_DIRECT_MAP_1M, -1);
 	return 0;
 }

 static void modify_pmd_page(pmd_t *pmdp, unsigned long addr,
 			    unsigned long flags)
 {
 	pmd_t new = *pmdp;

 	if (flags & SET_MEMORY_RO)
 		new = pmd_wrprotect(new);
 	else if (flags & SET_MEMORY_RW)
 		new = pmd_mkwrite_novma(pmd_mkdirty(new));
 	if (flags & SET_MEMORY_NX)
 		new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_NOEXEC));
 	else if (flags & SET_MEMORY_X)
 		new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_NOEXEC));
 	if (flags & SET_MEMORY_INV) {
 		new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_INVALID));
 	} else if (flags & SET_MEMORY_DEF) {
 		new = __pmd(pmd_val(new) & PMD_MASK);
 		new = set_pmd_bit(new, SEGMENT_KERNEL);
 		if (!MACHINE_HAS_NX)
 			new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_NOEXEC));
 	}
 	pgt_set((unsigned long *)pmdp, pmd_val(new), addr, CRDTE_DTT_SEGMENT);
 }

 static int walk_pmd_level(pud_t *pudp, unsigned long addr, unsigned long end,
 			  unsigned long flags)
 {
 	unsigned long next;
 	int need_split;
 	pmd_t *pmdp;
 	int rc = 0;

 	pmdp = pmd_offset(pudp, addr);
 	do {
 		if (pmd_none(*pmdp))
 			return -EINVAL;
 		next = pmd_addr_end(addr, end);
 		if (pmd_leaf(*pmdp)) {
 			need_split  = !!(flags & SET_MEMORY_4K);
 			need_split |= !!(addr & ~PMD_MASK);
 			need_split |= !!(addr + PMD_SIZE > next);
 			if (need_split) {
 				rc = split_pmd_page(pmdp, addr);
 				if (rc)
 					return rc;
 				continue;
 			}
 			modify_pmd_page(pmdp, addr, flags);
 		} else {
 			rc = walk_pte_level(pmdp, addr, next, flags);
 			if (rc)
 				return rc;
 		}
 		pmdp++;
 		addr = next;
 		cond_resched();
 	} while (addr < end);
 	return rc;
 }

 static int split_pud_page(pud_t *pudp, unsigned long addr)
 {
 	unsigned long pmd_addr, prot;
 	pmd_t *pm_dir, *pmdp;
 	pud_t new;
 	int i, ro, nx;

 	pm_dir = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 	if (!pm_dir)
 		return -ENOMEM;
 	pmd_addr = pud_pfn(*pudp) << PAGE_SHIFT;
 	ro = !!(pud_val(*pudp) & _REGION_ENTRY_PROTECT);
 	nx = !!(pud_val(*pudp) & _REGION_ENTRY_NOEXEC);
 	prot = pgprot_val(ro ? SEGMENT_KERNEL_RO : SEGMENT_KERNEL);
 	if (!nx)
 		prot &= ~_SEGMENT_ENTRY_NOEXEC;
 	pmdp = pm_dir;
 	for (i = 0; i < PTRS_PER_PMD; i++) {
 		set_pmd(pmdp, __pmd(pmd_addr | prot));
 		pmd_addr += PMD_SIZE;
 		pmdp++;
 	}
 	new = __pud(__pa(pm_dir) | _REGION3_ENTRY);
 	pgt_set((unsigned long *)pudp, pud_val(new), addr, CRDTE_DTT_REGION3);
 	update_page_count(PG_DIRECT_MAP_1M, PTRS_PER_PMD);
 	update_page_count(PG_DIRECT_MAP_2G, -1);
 	return 0;
 }

 static void modify_pud_page(pud_t *pudp, unsigned long addr,
 			    unsigned long flags)
 {
 	pud_t new = *pudp;

 	if (flags & SET_MEMORY_RO)
 		new = pud_wrprotect(new);
 	else if (flags & SET_MEMORY_RW)
 		new = pud_mkwrite(pud_mkdirty(new));
 	if (flags & SET_MEMORY_NX)
 		new = set_pud_bit(new, __pgprot(_REGION_ENTRY_NOEXEC));
 	else if (flags & SET_MEMORY_X)
 		new = clear_pud_bit(new, __pgprot(_REGION_ENTRY_NOEXEC));
 	if (flags & SET_MEMORY_INV) {
 		new = set_pud_bit(new, __pgprot(_REGION_ENTRY_INVALID));
 	} else if (flags & SET_MEMORY_DEF) {
 		new = __pud(pud_val(new) & PUD_MASK);
 		new = set_pud_bit(new, REGION3_KERNEL);
 		if (!MACHINE_HAS_NX)
 			new = clear_pud_bit(new, __pgprot(_REGION_ENTRY_NOEXEC));
 	}
 	pgt_set((unsigned long *)pudp, pud_val(new), addr, CRDTE_DTT_REGION3);
 }

 static int walk_pud_level(p4d_t *p4d, unsigned long addr, unsigned long end,
 			  unsigned long flags)
 {
 	unsigned long next;
 	int need_split;
 	pud_t *pudp;
 	int rc = 0;

 	pudp = pud_offset(p4d, addr);
 	do {
 		if (pud_none(*pudp))
 			return -EINVAL;
 		next = pud_addr_end(addr, end);
 		if (pud_leaf(*pudp)) {
 			need_split  = !!(flags & SET_MEMORY_4K);
 			need_split |= !!(addr & ~PUD_MASK);
 			need_split |= !!(addr + PUD_SIZE > next);
 			if (need_split) {
 				rc = split_pud_page(pudp, addr);
 				if (rc)
 					break;
 				continue;
 			}
 			modify_pud_page(pudp, addr, flags);
 		} else {
 			rc = walk_pmd_level(pudp, addr, next, flags);
 		}
 		pudp++;
 		addr = next;
 		cond_resched();
 	} while (addr < end && !rc);
 	return rc;
 }

 static int walk_p4d_level(pgd_t *pgd, unsigned long addr, unsigned long end,
 			  unsigned long flags)
 {
 	unsigned long next;
 	p4d_t *p4dp;
 	int rc = 0;

 	p4dp = p4d_offset(pgd, addr);
 	do {
 		if (p4d_none(*p4dp))
 			return -EINVAL;
 		next = p4d_addr_end(addr, end);
 		rc = walk_pud_level(p4dp, addr, next, flags);
 		p4dp++;
 		addr = next;
 		cond_resched();
 	} while (addr < end && !rc);
 	return rc;
 }

 DEFINE_MUTEX(cpa_mutex);

 static int change_page_attr(unsigned long addr, unsigned long end,
 			    unsigned long flags)
 {
 	unsigned long next;
 	int rc = -EINVAL;
 	pgd_t *pgdp;

 	pgdp = pgd_offset_k(addr);
 	do {
 		if (pgd_none(*pgdp))
 			break;
 		next = pgd_addr_end(addr, end);
 		rc = walk_p4d_level(pgdp, addr, next, flags);
 		if (rc)
 			break;
 		cond_resched();
 	} while (pgdp++, addr = next, addr < end && !rc);
 	return rc;
 }

 static int change_page_attr_alias(unsigned long addr, unsigned long end,
 				  unsigned long flags)
 {
 	unsigned long alias, offset, va_start, va_end;
 	struct vm_struct *area;
 	int rc = 0;

 	/*
 	 * Changes to read-only permissions on kernel VA mappings are also
 	 * applied to the kernel direct mapping. Execute permissions are
 	 * intentionally not transferred to keep all allocated pages within
 	 * the direct mapping non-executable.
 	 */
 	flags &= SET_MEMORY_RO | SET_MEMORY_RW;
 	if (!flags)
 		return 0;
 	area = NULL;
 	while (addr < end) {
 		if (!area)
 			area = find_vm_area((void *)addr);
 		if (!area || !(area->flags & VM_ALLOC))
 			return 0;
 		va_start = (unsigned long)area->addr;
 		va_end = va_start + area->nr_pages * PAGE_SIZE;
 		offset = (addr - va_start) >> PAGE_SHIFT;
 		alias = (unsigned long)page_address(area->pages[offset]);
 		rc = change_page_attr(alias, alias + PAGE_SIZE, flags);
 		if (rc)
 			break;
 		addr += PAGE_SIZE;
 		if (addr >= va_end)
 			area = NULL;
 	}
 	return rc;
 }

 int __set_memory(unsigned long addr, unsigned long numpages, unsigned long flags)
 {
 	unsigned long end;
 	int rc;

 	if (!MACHINE_HAS_NX)
 		flags &= ~(SET_MEMORY_NX | SET_MEMORY_X);
 	if (!flags)
 		return 0;
 	if (!numpages)
 		return 0;
 	addr &= PAGE_MASK;
 	end = addr + numpages * PAGE_SIZE;
 	mutex_lock(&cpa_mutex);
 	rc = change_page_attr(addr, end, flags);
 	if (rc)
 		goto out;
 	rc = change_page_attr_alias(addr, end, flags);
 out:
 	mutex_unlock(&cpa_mutex);
 	return rc;
 }

 int set_direct_map_invalid_noflush(struct page *page)
 {
 	return __set_memory((unsigned long)page_to_virt(page), 1, SET_MEMORY_INV);
 }

 int set_direct_map_default_noflush(struct page *page)
 {
 	return __set_memory((unsigned long)page_to_virt(page), 1, SET_MEMORY_DEF);
 }

 #if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)

 static void ipte_range(pte_t *pte, unsigned long address, int nr)
 {
 	int i;

 	if (test_facility(13)) {
 		__ptep_ipte_range(address, nr - 1, pte, IPTE_GLOBAL);
 		return;
 	}
 	for (i = 0; i < nr; i++) {
 		__ptep_ipte(address, pte, 0, 0, IPTE_GLOBAL);
 		address += PAGE_SIZE;
 		pte++;
 	}
 }

 void __kernel_map_pages(struct page *page, int numpages, int enable)
 {
 	unsigned long address;
 	pte_t *ptep, pte;
 	int nr, i, j;

 	for (i = 0; i < numpages;) {
 		address = (unsigned long)page_to_virt(page + i);
 		ptep = virt_to_kpte(address);
 		nr = (unsigned long)ptep >> ilog2(sizeof(long));
 		nr = PTRS_PER_PTE - (nr & (PTRS_PER_PTE - 1));
 		nr = min(numpages - i, nr);
 		if (enable) {
 			for (j = 0; j < nr; j++) {
 				pte = clear_pte_bit(*ptep, __pgprot(_PAGE_INVALID));
 				set_pte(ptep, pte);
 				address += PAGE_SIZE;
 				ptep++;
 			}
 		} else {
 			ipte_range(ptep, address, nr);
 		}
 		i += nr;
 	}
 }

 #endif /* CONFIG_DEBUG_PAGEALLOC */
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright IBM Corp. 2011
	* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
	*/
	#include <linux/hugetlb.h>
	#include <linux/proc_fs.h>
	#include <linux/vmalloc.h>
	#include <linux/mm.h>
	#include <asm/cacheflush.h>
	#include <asm/facility.h>
	#include <asm/pgalloc.h>
	#include <asm/kfence.h>
	#include <asm/page.h>
	#include <asm/set_memory.h>

	static inline unsigned long sske_frame(unsigned long addr, unsigned char skey)
	{
	asm volatile(".insn rrf,0xb22b0000,%[skey],%[addr],1,0"
	: [addr] "+a" (addr) : [skey] "d" (skey));
	return addr;
	}

	void __storage_key_init_range(unsigned long start, unsigned long end)
	{
	unsigned long boundary, size;

	while (start < end) {
	if (MACHINE_HAS_EDAT1) {
	/* set storage keys for a 1MB frame */
	size = 1UL << 20;
	boundary = (start + size) & ~(size - 1);
	if (boundary <= end) {
	do {
	start = sske_frame(start, PAGE_DEFAULT_KEY);
	} while (start < boundary);
	continue;
	}
	}
	page_set_storage_key(start, PAGE_DEFAULT_KEY, 1);
	start += PAGE_SIZE;
	}
	}

	#ifdef CONFIG_PROC_FS
	atomic_long_t __bootdata_preserved(direct_pages_count[PG_DIRECT_MAP_MAX]);

	void arch_report_meminfo(struct seq_file *m)
	{
	seq_printf(m, "DirectMap4k: %8lu kB\n",
	atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_4K]) << 2);
	seq_printf(m, "DirectMap1M: %8lu kB\n",
	atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_1M]) << 10);
	seq_printf(m, "DirectMap2G: %8lu kB\n",
	atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_2G]) << 21);
	}
	#endif /* CONFIG_PROC_FS */

	static void pgt_set(unsigned long *old, unsigned long new, unsigned long addr,
	unsigned long dtt)
	{
	unsigned long *table, mask;

	mask = 0;
	if (MACHINE_HAS_EDAT2) {
	switch (dtt) {
	case CRDTE_DTT_REGION3:
	mask = ~(PTRS_PER_PUD * sizeof(pud_t) - 1);
	break;
	case CRDTE_DTT_SEGMENT:
	mask = ~(PTRS_PER_PMD * sizeof(pmd_t) - 1);
	break;
	case CRDTE_DTT_PAGE:
	mask = ~(PTRS_PER_PTE * sizeof(pte_t) - 1);
	break;
	}
	table = (unsigned long *)((unsigned long)old & mask);
	crdte(*old, new, table, dtt, addr, S390_lowcore.kernel_asce.val);
	} else if (MACHINE_HAS_IDTE) {
	cspg(old, *old, new);
	} else {
	csp((unsigned int )old + 1, old, new);
	}
	}

	static int walk_pte_level(pmd_t *pmdp, unsigned long addr, unsigned long end,
	unsigned long flags)
	{
	pte_t *ptep, new;

	if (flags == SET_MEMORY_4K)
	return 0;
	ptep = pte_offset_kernel(pmdp, addr);
	do {
	new = *ptep;
	if (pte_none(new))
	return -EINVAL;
	if (flags & SET_MEMORY_RO)
	new = pte_wrprotect(new);
	else if (flags & SET_MEMORY_RW)
	new = pte_mkwrite_novma(pte_mkdirty(new));
	if (flags & SET_MEMORY_NX)
	new = set_pte_bit(new, __pgprot(_PAGE_NOEXEC));
	else if (flags & SET_MEMORY_X)
	new = clear_pte_bit(new, __pgprot(_PAGE_NOEXEC));
	if (flags & SET_MEMORY_INV) {
	new = set_pte_bit(new, __pgprot(_PAGE_INVALID));
	} else if (flags & SET_MEMORY_DEF) {
	new = __pte(pte_val(new) & PAGE_MASK);
	new = set_pte_bit(new, PAGE_KERNEL);
	if (!MACHINE_HAS_NX)
	new = clear_pte_bit(new, __pgprot(_PAGE_NOEXEC));
	}
	pgt_set((unsigned long *)ptep, pte_val(new), addr, CRDTE_DTT_PAGE);
	ptep++;
	addr += PAGE_SIZE;
	cond_resched();
	} while (addr < end);
	return 0;
	}

	static int split_pmd_page(pmd_t *pmdp, unsigned long addr)
	{
	unsigned long pte_addr, prot;
	pte_t pt_dir, ptep;
	pmd_t new;
	int i, ro, nx;

	pt_dir = vmem_pte_alloc();
	if (!pt_dir)
	return -ENOMEM;
	pte_addr = pmd_pfn(*pmdp) << PAGE_SHIFT;
	ro = !!(pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT);
	nx = !!(pmd_val(*pmdp) & _SEGMENT_ENTRY_NOEXEC);
	prot = pgprot_val(ro ? PAGE_KERNEL_RO : PAGE_KERNEL);
	if (!nx)
	prot &= ~_PAGE_NOEXEC;
	ptep = pt_dir;
	for (i = 0; i < PTRS_PER_PTE; i++) {
	set_pte(ptep, __pte(pte_addr \| prot));
	pte_addr += PAGE_SIZE;
	ptep++;
	}
	new = __pmd(__pa(pt_dir) \| _SEGMENT_ENTRY);
	pgt_set((unsigned long *)pmdp, pmd_val(new), addr, CRDTE_DTT_SEGMENT);
	update_page_count(PG_DIRECT_MAP_4K, PTRS_PER_PTE);
	update_page_count(PG_DIRECT_MAP_1M, -1);
	return 0;
	}

	static void modify_pmd_page(pmd_t *pmdp, unsigned long addr,
	unsigned long flags)
	{
	pmd_t new = *pmdp;

	if (flags & SET_MEMORY_RO)
	new = pmd_wrprotect(new);
	else if (flags & SET_MEMORY_RW)
	new = pmd_mkwrite_novma(pmd_mkdirty(new));
	if (flags & SET_MEMORY_NX)
	new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_NOEXEC));
	else if (flags & SET_MEMORY_X)
	new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_NOEXEC));
	if (flags & SET_MEMORY_INV) {
	new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_INVALID));
	} else if (flags & SET_MEMORY_DEF) {
	new = __pmd(pmd_val(new) & PMD_MASK);
	new = set_pmd_bit(new, SEGMENT_KERNEL);
	if (!MACHINE_HAS_NX)
	new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_NOEXEC));
	}
	pgt_set((unsigned long *)pmdp, pmd_val(new), addr, CRDTE_DTT_SEGMENT);
	}

	static int walk_pmd_level(pud_t *pudp, unsigned long addr, unsigned long end,
	unsigned long flags)
	{
	unsigned long next;
	int need_split;
	pmd_t *pmdp;
	int rc = 0;

	pmdp = pmd_offset(pudp, addr);
	do {
	if (pmd_none(*pmdp))
	return -EINVAL;
	next = pmd_addr_end(addr, end);
	if (pmd_leaf(*pmdp)) {
	need_split = !!(flags & SET_MEMORY_4K);
	need_split \|= !!(addr & ~PMD_MASK);
	need_split \|= !!(addr + PMD_SIZE > next);
	if (need_split) {
	rc = split_pmd_page(pmdp, addr);
	if (rc)
	return rc;
	continue;
	}
	modify_pmd_page(pmdp, addr, flags);
	} else {
	rc = walk_pte_level(pmdp, addr, next, flags);
	if (rc)
	return rc;
	}
	pmdp++;
	addr = next;
	cond_resched();
	} while (addr < end);
	return rc;
	}

	static int split_pud_page(pud_t *pudp, unsigned long addr)
	{
	unsigned long pmd_addr, prot;
	pmd_t pm_dir, pmdp;
	pud_t new;
	int i, ro, nx;

	pm_dir = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
	if (!pm_dir)
	return -ENOMEM;
	pmd_addr = pud_pfn(*pudp) << PAGE_SHIFT;
	ro = !!(pud_val(*pudp) & _REGION_ENTRY_PROTECT);
	nx = !!(pud_val(*pudp) & _REGION_ENTRY_NOEXEC);
	prot = pgprot_val(ro ? SEGMENT_KERNEL_RO : SEGMENT_KERNEL);
	if (!nx)
	prot &= ~_SEGMENT_ENTRY_NOEXEC;
	pmdp = pm_dir;
	for (i = 0; i < PTRS_PER_PMD; i++) {
	set_pmd(pmdp, __pmd(pmd_addr \| prot));
	pmd_addr += PMD_SIZE;
	pmdp++;
	}
	new = __pud(__pa(pm_dir) \| _REGION3_ENTRY);
	pgt_set((unsigned long *)pudp, pud_val(new), addr, CRDTE_DTT_REGION3);
	update_page_count(PG_DIRECT_MAP_1M, PTRS_PER_PMD);
	update_page_count(PG_DIRECT_MAP_2G, -1);
	return 0;
	}

	static void modify_pud_page(pud_t *pudp, unsigned long addr,
	unsigned long flags)
	{
	pud_t new = *pudp;

	if (flags & SET_MEMORY_RO)
	new = pud_wrprotect(new);
	else if (flags & SET_MEMORY_RW)
	new = pud_mkwrite(pud_mkdirty(new));
	if (flags & SET_MEMORY_NX)
	new = set_pud_bit(new, __pgprot(_REGION_ENTRY_NOEXEC));
	else if (flags & SET_MEMORY_X)
	new = clear_pud_bit(new, __pgprot(_REGION_ENTRY_NOEXEC));
	if (flags & SET_MEMORY_INV) {
	new = set_pud_bit(new, __pgprot(_REGION_ENTRY_INVALID));
	} else if (flags & SET_MEMORY_DEF) {
	new = __pud(pud_val(new) & PUD_MASK);
	new = set_pud_bit(new, REGION3_KERNEL);
	if (!MACHINE_HAS_NX)
	new = clear_pud_bit(new, __pgprot(_REGION_ENTRY_NOEXEC));
	}
	pgt_set((unsigned long *)pudp, pud_val(new), addr, CRDTE_DTT_REGION3);
	}

	static int walk_pud_level(p4d_t *p4d, unsigned long addr, unsigned long end,
	unsigned long flags)
	{
	unsigned long next;
	int need_split;
	pud_t *pudp;
	int rc = 0;

	pudp = pud_offset(p4d, addr);
	do {
	if (pud_none(*pudp))
	return -EINVAL;
	next = pud_addr_end(addr, end);
	if (pud_leaf(*pudp)) {
	need_split = !!(flags & SET_MEMORY_4K);
	need_split \|= !!(addr & ~PUD_MASK);
	need_split \|= !!(addr + PUD_SIZE > next);
	if (need_split) {
	rc = split_pud_page(pudp, addr);
	if (rc)
	break;
	continue;
	}
	modify_pud_page(pudp, addr, flags);
	} else {
	rc = walk_pmd_level(pudp, addr, next, flags);
	}
	pudp++;
	addr = next;
	cond_resched();
	} while (addr < end && !rc);
	return rc;
	}

	static int walk_p4d_level(pgd_t *pgd, unsigned long addr, unsigned long end,
	unsigned long flags)
	{
	unsigned long next;
	p4d_t *p4dp;
	int rc = 0;

	p4dp = p4d_offset(pgd, addr);
	do {
	if (p4d_none(*p4dp))
	return -EINVAL;
	next = p4d_addr_end(addr, end);
	rc = walk_pud_level(p4dp, addr, next, flags);
	p4dp++;
	addr = next;
	cond_resched();
	} while (addr < end && !rc);
	return rc;
	}

	DEFINE_MUTEX(cpa_mutex);

	static int change_page_attr(unsigned long addr, unsigned long end,
	unsigned long flags)
	{
	unsigned long next;
	int rc = -EINVAL;
	pgd_t *pgdp;

	pgdp = pgd_offset_k(addr);
	do {
	if (pgd_none(*pgdp))
	break;
	next = pgd_addr_end(addr, end);
	rc = walk_p4d_level(pgdp, addr, next, flags);
	if (rc)
	break;
	cond_resched();
	} while (pgdp++, addr = next, addr < end && !rc);
	return rc;
	}

	static int change_page_attr_alias(unsigned long addr, unsigned long end,
	unsigned long flags)
	{
	unsigned long alias, offset, va_start, va_end;
	struct vm_struct *area;
	int rc = 0;

	/*
	* Changes to read-only permissions on kernel VA mappings are also
	* applied to the kernel direct mapping. Execute permissions are
	* intentionally not transferred to keep all allocated pages within
	* the direct mapping non-executable.
	*/
	flags &= SET_MEMORY_RO \| SET_MEMORY_RW;
	if (!flags)
	return 0;
	area = NULL;
	while (addr < end) {
	if (!area)
	area = find_vm_area((void *)addr);
	if (!area \|\| !(area->flags & VM_ALLOC))
	return 0;
	va_start = (unsigned long)area->addr;
	va_end = va_start + area->nr_pages * PAGE_SIZE;
	offset = (addr - va_start) >> PAGE_SHIFT;
	alias = (unsigned long)page_address(area->pages[offset]);
	rc = change_page_attr(alias, alias + PAGE_SIZE, flags);
	if (rc)
	break;
	addr += PAGE_SIZE;
	if (addr >= va_end)
	area = NULL;
	}
	return rc;
	}

	int __set_memory(unsigned long addr, unsigned long numpages, unsigned long flags)
	{
	unsigned long end;
	int rc;

	if (!MACHINE_HAS_NX)
	flags &= ~(SET_MEMORY_NX \| SET_MEMORY_X);
	if (!flags)
	return 0;
	if (!numpages)
	return 0;
	addr &= PAGE_MASK;
	end = addr + numpages * PAGE_SIZE;
	mutex_lock(&cpa_mutex);
	rc = change_page_attr(addr, end, flags);
	if (rc)
	goto out;
	rc = change_page_attr_alias(addr, end, flags);
	out:
	mutex_unlock(&cpa_mutex);
	return rc;
	}

	int set_direct_map_invalid_noflush(struct page *page)
	{
	return __set_memory((unsigned long)page_to_virt(page), 1, SET_MEMORY_INV);
	}

	int set_direct_map_default_noflush(struct page *page)
	{
	return __set_memory((unsigned long)page_to_virt(page), 1, SET_MEMORY_DEF);
	}

	#if defined(CONFIG_DEBUG_PAGEALLOC) \|\| defined(CONFIG_KFENCE)

	static void ipte_range(pte_t *pte, unsigned long address, int nr)
	{
	int i;

	if (test_facility(13)) {
	__ptep_ipte_range(address, nr - 1, pte, IPTE_GLOBAL);
	return;
	}
	for (i = 0; i < nr; i++) {
	__ptep_ipte(address, pte, 0, 0, IPTE_GLOBAL);
	address += PAGE_SIZE;
	pte++;
	}
	}

	void __kernel_map_pages(struct page *page, int numpages, int enable)
	{
	unsigned long address;
	pte_t *ptep, pte;
	int nr, i, j;

	for (i = 0; i < numpages;) {
	address = (unsigned long)page_to_virt(page + i);
	ptep = virt_to_kpte(address);
	nr = (unsigned long)ptep >> ilog2(sizeof(long));
	nr = PTRS_PER_PTE - (nr & (PTRS_PER_PTE - 1));
	nr = min(numpages - i, nr);
	if (enable) {
	for (j = 0; j < nr; j++) {
	pte = clear_pte_bit(*ptep, __pgprot(_PAGE_INVALID));
	set_pte(ptep, pte);
	address += PAGE_SIZE;
	ptep++;
	}
	} else {
	ipte_range(ptep, address, nr);
	}
	i += nr;
	}
	}

	#endif /* CONFIG_DEBUG_PAGEALLOC */