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

 // SPDX-License-Identifier: GPL-2.0
 /*
  *    Copyright IBM Corp. 2006
  */

 #include <linux/memory_hotplug.h>
 #include <linux/memblock.h>
 #include <linux/pfn.h>
 #include <linux/mm.h>
 #include <linux/init.h>
 #include <linux/list.h>
 #include <linux/hugetlb.h>
 #include <linux/slab.h>
 #include <linux/sort.h>
 #include <asm/cacheflush.h>
 #include <asm/nospec-branch.h>
 #include <asm/pgalloc.h>
 #include <asm/setup.h>
 #include <asm/tlbflush.h>
 #include <asm/sections.h>
 #include <asm/set_memory.h>

 static DEFINE_MUTEX(vmem_mutex);

 static void __ref *vmem_alloc_pages(unsigned int order)
 {
 	unsigned long size = PAGE_SIZE << order;

 	if (slab_is_available())
 		return (void *)__get_free_pages(GFP_KERNEL, order);
 	return memblock_alloc(size, size);
 }

 static void vmem_free_pages(unsigned long addr, int order)
 {
 	/* We don't expect boot memory to be removed ever. */
 	if (!slab_is_available() ||
 	    WARN_ON_ONCE(PageReserved(virt_to_page((void *)addr))))
 		return;
 	free_pages(addr, order);
 }

 void *vmem_crst_alloc(unsigned long val)
 {
 	unsigned long *table;

 	table = vmem_alloc_pages(CRST_ALLOC_ORDER);
 	if (table)
 		crst_table_init(table, val);
 	return table;
 }

 pte_t __ref *vmem_pte_alloc(void)
 {
 	unsigned long size = PTRS_PER_PTE * sizeof(pte_t);
 	pte_t *pte;

 	if (slab_is_available())
 		pte = (pte_t *) page_table_alloc(&init_mm);
 	else
 		pte = (pte_t *) memblock_alloc(size, size);
 	if (!pte)
 		return NULL;
 	memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
 	return pte;
 }

 static void vmem_pte_free(unsigned long *table)
 {
 	/* We don't expect boot memory to be removed ever. */
 	if (!slab_is_available() ||
 	    WARN_ON_ONCE(PageReserved(virt_to_page(table))))
 		return;
 	page_table_free(&init_mm, table);
 }

 #define PAGE_UNUSED 0xFD

 /*
  * The unused vmemmap range, which was not yet memset(PAGE_UNUSED) ranges
  * from unused_sub_pmd_start to next PMD_SIZE boundary.
  */
 static unsigned long unused_sub_pmd_start;

 static void vmemmap_flush_unused_sub_pmd(void)
 {
 	if (!unused_sub_pmd_start)
 		return;
 	memset((void *)unused_sub_pmd_start, PAGE_UNUSED,
 	       ALIGN(unused_sub_pmd_start, PMD_SIZE) - unused_sub_pmd_start);
 	unused_sub_pmd_start = 0;
 }

 static void vmemmap_mark_sub_pmd_used(unsigned long start, unsigned long end)
 {
 	/*
 	 * As we expect to add in the same granularity as we remove, it's
 	 * sufficient to mark only some piece used to block the memmap page from
 	 * getting removed (just in case the memmap never gets initialized,
 	 * e.g., because the memory block never gets onlined).
 	 */
 	memset((void *)start, 0, sizeof(struct page));
 }

 static void vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
 {
 	/*
 	 * We only optimize if the new used range directly follows the
 	 * previously unused range (esp., when populating consecutive sections).
 	 */
 	if (unused_sub_pmd_start == start) {
 		unused_sub_pmd_start = end;
 		if (likely(IS_ALIGNED(unused_sub_pmd_start, PMD_SIZE)))
 			unused_sub_pmd_start = 0;
 		return;
 	}
 	vmemmap_flush_unused_sub_pmd();
 	vmemmap_mark_sub_pmd_used(start, end);
 }

 static void vmemmap_use_new_sub_pmd(unsigned long start, unsigned long end)
 {
 	unsigned long page = ALIGN_DOWN(start, PMD_SIZE);

 	vmemmap_flush_unused_sub_pmd();

 	/* Could be our memmap page is filled with PAGE_UNUSED already ... */
 	vmemmap_mark_sub_pmd_used(start, end);

 	/* Mark the unused parts of the new memmap page PAGE_UNUSED. */
 	if (!IS_ALIGNED(start, PMD_SIZE))
 		memset((void *)page, PAGE_UNUSED, start - page);
 	/*
 	 * We want to avoid memset(PAGE_UNUSED) when populating the vmemmap of
 	 * consecutive sections. Remember for the last added PMD the last
 	 * unused range in the populated PMD.
 	 */
 	if (!IS_ALIGNED(end, PMD_SIZE))
 		unused_sub_pmd_start = end;
 }

 /* Returns true if the PMD is completely unused and can be freed. */
 static bool vmemmap_unuse_sub_pmd(unsigned long start, unsigned long end)
 {
 	unsigned long page = ALIGN_DOWN(start, PMD_SIZE);

 	vmemmap_flush_unused_sub_pmd();
 	memset((void *)start, PAGE_UNUSED, end - start);
 	return !memchr_inv((void *)page, PAGE_UNUSED, PMD_SIZE);
 }

 /* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
 static int __ref modify_pte_table(pmd_t *pmd, unsigned long addr,
 				  unsigned long end, bool add, bool direct)
 {
 	unsigned long prot, pages = 0;
 	int ret = -ENOMEM;
 	pte_t *pte;

 	prot = pgprot_val(PAGE_KERNEL);
 	if (!MACHINE_HAS_NX)
 		prot &= ~_PAGE_NOEXEC;

 	pte = pte_offset_kernel(pmd, addr);
 	for (; addr < end; addr += PAGE_SIZE, pte++) {
 		if (!add) {
 			if (pte_none(*pte))
 				continue;
 			if (!direct)
 				vmem_free_pages((unsigned long) pfn_to_virt(pte_pfn(*pte)), 0);
 			pte_clear(&init_mm, addr, pte);
 		} else if (pte_none(*pte)) {
 			if (!direct) {
 				void *new_page = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);

 				if (!new_page)
 					goto out;
 				set_pte(pte, __pte(__pa(new_page) | prot));
 			} else {
 				set_pte(pte, __pte(__pa(addr) | prot));
 			}
 		} else {
 			continue;
 		}
 		pages++;
 	}
 	ret = 0;
 out:
 	if (direct)
 		update_page_count(PG_DIRECT_MAP_4K, add ? pages : -pages);
 	return ret;
 }

 static void try_free_pte_table(pmd_t *pmd, unsigned long start)
 {
 	pte_t *pte;
 	int i;

 	/* We can safely assume this is fully in 1:1 mapping & vmemmap area */
 	pte = pte_offset_kernel(pmd, start);
 	for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
 		if (!pte_none(*pte))
 			return;
 	}
 	vmem_pte_free((unsigned long *) pmd_deref(*pmd));
 	pmd_clear(pmd);
 }

 /* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
 static int __ref modify_pmd_table(pud_t *pud, unsigned long addr,
 				  unsigned long end, bool add, bool direct)
 {
 	unsigned long next, prot, pages = 0;
 	int ret = -ENOMEM;
 	pmd_t *pmd;
 	pte_t *pte;

 	prot = pgprot_val(SEGMENT_KERNEL);
 	if (!MACHINE_HAS_NX)
 		prot &= ~_SEGMENT_ENTRY_NOEXEC;

 	pmd = pmd_offset(pud, addr);
 	for (; addr < end; addr = next, pmd++) {
 		next = pmd_addr_end(addr, end);
 		if (!add) {
 			if (pmd_none(*pmd))
 				continue;
 			if (pmd_large(*pmd)) {
 				if (IS_ALIGNED(addr, PMD_SIZE) &&
 				    IS_ALIGNED(next, PMD_SIZE)) {
 					if (!direct)
 						vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE));
 					pmd_clear(pmd);
 					pages++;
 				} else if (!direct && vmemmap_unuse_sub_pmd(addr, next)) {
 					vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE));
 					pmd_clear(pmd);
 				}
 				continue;
 			}
 		} else if (pmd_none(*pmd)) {
 			if (IS_ALIGNED(addr, PMD_SIZE) &&
 			    IS_ALIGNED(next, PMD_SIZE) &&
 			    MACHINE_HAS_EDAT1 && direct &&
 			    !debug_pagealloc_enabled()) {
 				set_pmd(pmd, __pmd(__pa(addr) | prot));
 				pages++;
 				continue;
 			} else if (!direct && MACHINE_HAS_EDAT1) {
 				void *new_page;

 				/*
 				 * Use 1MB frames for vmemmap if available. We
 				 * always use large frames even if they are only
 				 * partially used. Otherwise we would have also
 				 * page tables since vmemmap_populate gets
 				 * called for each section separately.
 				 */
 				new_page = vmemmap_alloc_block(PMD_SIZE, NUMA_NO_NODE);
 				if (new_page) {
 					set_pmd(pmd, __pmd(__pa(new_page) | prot));
 					if (!IS_ALIGNED(addr, PMD_SIZE) ||
 					    !IS_ALIGNED(next, PMD_SIZE)) {
 						vmemmap_use_new_sub_pmd(addr, next);
 					}
 					continue;
 				}
 			}
 			pte = vmem_pte_alloc();
 			if (!pte)
 				goto out;
 			pmd_populate(&init_mm, pmd, pte);
 		} else if (pmd_large(*pmd)) {
 			if (!direct)
 				vmemmap_use_sub_pmd(addr, next);
 			continue;
 		}
 		ret = modify_pte_table(pmd, addr, next, add, direct);
 		if (ret)
 			goto out;
 		if (!add)
 			try_free_pte_table(pmd, addr & PMD_MASK);
 	}
 	ret = 0;
 out:
 	if (direct)
 		update_page_count(PG_DIRECT_MAP_1M, add ? pages : -pages);
 	return ret;
 }

 static void try_free_pmd_table(pud_t *pud, unsigned long start)
 {
 	pmd_t *pmd;
 	int i;

 	pmd = pmd_offset(pud, start);
 	for (i = 0; i < PTRS_PER_PMD; i++, pmd++)
 		if (!pmd_none(*pmd))
 			return;
 	vmem_free_pages(pud_deref(*pud), CRST_ALLOC_ORDER);
 	pud_clear(pud);
 }

 static int modify_pud_table(p4d_t *p4d, unsigned long addr, unsigned long end,
 			    bool add, bool direct)
 {
 	unsigned long next, prot, pages = 0;
 	int ret = -ENOMEM;
 	pud_t *pud;
 	pmd_t *pmd;

 	prot = pgprot_val(REGION3_KERNEL);
 	if (!MACHINE_HAS_NX)
 		prot &= ~_REGION_ENTRY_NOEXEC;
 	pud = pud_offset(p4d, addr);
 	for (; addr < end; addr = next, pud++) {
 		next = pud_addr_end(addr, end);
 		if (!add) {
 			if (pud_none(*pud))
 				continue;
 			if (pud_large(*pud)) {
 				if (IS_ALIGNED(addr, PUD_SIZE) &&
 				    IS_ALIGNED(next, PUD_SIZE)) {
 					pud_clear(pud);
 					pages++;
 				}
 				continue;
 			}
 		} else if (pud_none(*pud)) {
 			if (IS_ALIGNED(addr, PUD_SIZE) &&
 			    IS_ALIGNED(next, PUD_SIZE) &&
 			    MACHINE_HAS_EDAT2 && direct &&
 			    !debug_pagealloc_enabled()) {
 				set_pud(pud, __pud(__pa(addr) | prot));
 				pages++;
 				continue;
 			}
 			pmd = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 			if (!pmd)
 				goto out;
 			pud_populate(&init_mm, pud, pmd);
 		} else if (pud_large(*pud)) {
 			continue;
 		}
 		ret = modify_pmd_table(pud, addr, next, add, direct);
 		if (ret)
 			goto out;
 		if (!add)
 			try_free_pmd_table(pud, addr & PUD_MASK);
 	}
 	ret = 0;
 out:
 	if (direct)
 		update_page_count(PG_DIRECT_MAP_2G, add ? pages : -pages);
 	return ret;
 }

 static void try_free_pud_table(p4d_t *p4d, unsigned long start)
 {
 	pud_t *pud;
 	int i;

 	pud = pud_offset(p4d, start);
 	for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
 		if (!pud_none(*pud))
 			return;
 	}
 	vmem_free_pages(p4d_deref(*p4d), CRST_ALLOC_ORDER);
 	p4d_clear(p4d);
 }

 static int modify_p4d_table(pgd_t *pgd, unsigned long addr, unsigned long end,
 			    bool add, bool direct)
 {
 	unsigned long next;
 	int ret = -ENOMEM;
 	p4d_t *p4d;
 	pud_t *pud;

 	p4d = p4d_offset(pgd, addr);
 	for (; addr < end; addr = next, p4d++) {
 		next = p4d_addr_end(addr, end);
 		if (!add) {
 			if (p4d_none(*p4d))
 				continue;
 		} else if (p4d_none(*p4d)) {
 			pud = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
 			if (!pud)
 				goto out;
 			p4d_populate(&init_mm, p4d, pud);
 		}
 		ret = modify_pud_table(p4d, addr, next, add, direct);
 		if (ret)
 			goto out;
 		if (!add)
 			try_free_pud_table(p4d, addr & P4D_MASK);
 	}
 	ret = 0;
 out:
 	return ret;
 }

 static void try_free_p4d_table(pgd_t *pgd, unsigned long start)
 {
 	p4d_t *p4d;
 	int i;

 	p4d = p4d_offset(pgd, start);
 	for (i = 0; i < PTRS_PER_P4D; i++, p4d++) {
 		if (!p4d_none(*p4d))
 			return;
 	}
 	vmem_free_pages(pgd_deref(*pgd), CRST_ALLOC_ORDER);
 	pgd_clear(pgd);
 }

 static int modify_pagetable(unsigned long start, unsigned long end, bool add,
 			    bool direct)
 {
 	unsigned long addr, next;
 	int ret = -ENOMEM;
 	pgd_t *pgd;
 	p4d_t *p4d;

 	if (WARN_ON_ONCE(!PAGE_ALIGNED(start | end)))
 		return -EINVAL;
 	/* Don't mess with any tables not fully in 1:1 mapping & vmemmap area */
 	if (WARN_ON_ONCE(end > VMALLOC_START))
 		return -EINVAL;
 	for (addr = start; addr < end; addr = next) {
 		next = pgd_addr_end(addr, end);
 		pgd = pgd_offset_k(addr);

 		if (!add) {
 			if (pgd_none(*pgd))
 				continue;
 		} else if (pgd_none(*pgd)) {
 			p4d = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
 			if (!p4d)
 				goto out;
 			pgd_populate(&init_mm, pgd, p4d);
 		}
 		ret = modify_p4d_table(pgd, addr, next, add, direct);
 		if (ret)
 			goto out;
 		if (!add)
 			try_free_p4d_table(pgd, addr & PGDIR_MASK);
 	}
 	ret = 0;
 out:
 	if (!add)
 		flush_tlb_kernel_range(start, end);
 	return ret;
 }

 static int add_pagetable(unsigned long start, unsigned long end, bool direct)
 {
 	return modify_pagetable(start, end, true, direct);
 }

 static int remove_pagetable(unsigned long start, unsigned long end, bool direct)
 {
 	return modify_pagetable(start, end, false, direct);
 }

 /*
  * Add a physical memory range to the 1:1 mapping.
  */
 static int vmem_add_range(unsigned long start, unsigned long size)
 {
 	start = (unsigned long)__va(start);
 	return add_pagetable(start, start + size, true);
 }

 /*
  * Remove a physical memory range from the 1:1 mapping.
  */
 static void vmem_remove_range(unsigned long start, unsigned long size)
 {
 	start = (unsigned long)__va(start);
 	remove_pagetable(start, start + size, true);
 }

 /*
  * Add a backed mem_map array to the virtual mem_map array.
  */
 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 			       struct vmem_altmap *altmap)
 {
 	int ret;

 	mutex_lock(&vmem_mutex);
 	/* We don't care about the node, just use NUMA_NO_NODE on allocations */
 	ret = add_pagetable(start, end, false);
 	if (ret)
 		remove_pagetable(start, end, false);
 	mutex_unlock(&vmem_mutex);
 	return ret;
 }

 void vmemmap_free(unsigned long start, unsigned long end,
 		  struct vmem_altmap *altmap)
 {
 	mutex_lock(&vmem_mutex);
 	remove_pagetable(start, end, false);
 	mutex_unlock(&vmem_mutex);
 }

 void vmem_remove_mapping(unsigned long start, unsigned long size)
 {
 	mutex_lock(&vmem_mutex);
 	vmem_remove_range(start, size);
 	mutex_unlock(&vmem_mutex);
 }

 struct range arch_get_mappable_range(void)
 {
 	struct range mhp_range;

 	mhp_range.start = 0;
 	mhp_range.end = max_mappable - 1;
 	return mhp_range;
 }

 int vmem_add_mapping(unsigned long start, unsigned long size)
 {
 	struct range range = arch_get_mappable_range();
 	int ret;

 	if (start < range.start ||
 	    start + size > range.end + 1 ||
 	    start + size < start)
 		return -ERANGE;

 	mutex_lock(&vmem_mutex);
 	ret = vmem_add_range(start, size);
 	if (ret)
 		vmem_remove_range(start, size);
 	mutex_unlock(&vmem_mutex);
 	return ret;
 }

 /*
  * Allocate new or return existing page-table entry, but do not map it
  * to any physical address. If missing, allocate segment- and region-
  * table entries along. Meeting a large segment- or region-table entry
  * while traversing is an error, since the function is expected to be
  * called against virtual regions reserved for 4KB mappings only.
  */
 pte_t *vmem_get_alloc_pte(unsigned long addr, bool alloc)
 {
 	pte_t *ptep = NULL;
 	pgd_t *pgd;
 	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;

 	pgd = pgd_offset_k(addr);
 	if (pgd_none(*pgd)) {
 		if (!alloc)
 			goto out;
 		p4d = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
 		if (!p4d)
 			goto out;
 		pgd_populate(&init_mm, pgd, p4d);
 	}
 	p4d = p4d_offset(pgd, addr);
 	if (p4d_none(*p4d)) {
 		if (!alloc)
 			goto out;
 		pud = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
 		if (!pud)
 			goto out;
 		p4d_populate(&init_mm, p4d, pud);
 	}
 	pud = pud_offset(p4d, addr);
 	if (pud_none(*pud)) {
 		if (!alloc)
 			goto out;
 		pmd = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 		if (!pmd)
 			goto out;
 		pud_populate(&init_mm, pud, pmd);
 	} else if (WARN_ON_ONCE(pud_large(*pud))) {
 		goto out;
 	}
 	pmd = pmd_offset(pud, addr);
 	if (pmd_none(*pmd)) {
 		if (!alloc)
 			goto out;
 		pte = vmem_pte_alloc();
 		if (!pte)
 			goto out;
 		pmd_populate(&init_mm, pmd, pte);
 	} else if (WARN_ON_ONCE(pmd_large(*pmd))) {
 		goto out;
 	}
 	ptep = pte_offset_kernel(pmd, addr);
 out:
 	return ptep;
 }

 int __vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot, bool alloc)
 {
 	pte_t *ptep, pte;

 	if (!IS_ALIGNED(addr, PAGE_SIZE))
 		return -EINVAL;
 	ptep = vmem_get_alloc_pte(addr, alloc);
 	if (!ptep)
 		return -ENOMEM;
 	__ptep_ipte(addr, ptep, 0, 0, IPTE_GLOBAL);
 	pte = mk_pte_phys(phys, prot);
 	set_pte(ptep, pte);
 	return 0;
 }

 int vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot)
 {
 	int rc;

 	mutex_lock(&vmem_mutex);
 	rc = __vmem_map_4k_page(addr, phys, prot, true);
 	mutex_unlock(&vmem_mutex);
 	return rc;
 }

 void vmem_unmap_4k_page(unsigned long addr)
 {
 	pte_t *ptep;

 	mutex_lock(&vmem_mutex);
 	ptep = virt_to_kpte(addr);
 	__ptep_ipte(addr, ptep, 0, 0, IPTE_GLOBAL);
 	pte_clear(&init_mm, addr, ptep);
 	mutex_unlock(&vmem_mutex);
 }

 void __init vmem_map_init(void)
 {
 	__set_memory_rox(_stext, _etext);
 	__set_memory_ro(_etext, __end_rodata);
 	__set_memory_rox(_sinittext, _einittext);
 	__set_memory_rox(__stext_amode31, __etext_amode31);
 	/*
 	 * If the BEAR-enhancement facility is not installed the first
 	 * prefix page is used to return to the previous context with
 	 * an LPSWE instruction and therefore must be executable.
 	 */
 	if (!static_key_enabled(&cpu_has_bear))
 		set_memory_x(0, 1);
 	if (debug_pagealloc_enabled()) {
 		/*
 		 * Use RELOC_HIDE() as long as __va(0) translates to NULL,
 		 * since performing pointer arithmetic on a NULL pointer
 		 * has undefined behavior and generates compiler warnings.
 		 */
 		__set_memory_4k(__va(0), RELOC_HIDE(__va(0), ident_map_size));
 	}
 	if (MACHINE_HAS_NX)
 		ctl_set_bit(0, 20);
 	pr_info("Write protected kernel read-only data: %luk\n",
 		(unsigned long)(__end_rodata - _stext) >> 10);
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright IBM Corp. 2006
	*/

	#include <linux/memory_hotplug.h>
	#include <linux/memblock.h>
	#include <linux/pfn.h>
	#include <linux/mm.h>
	#include <linux/init.h>
	#include <linux/list.h>
	#include <linux/hugetlb.h>
	#include <linux/slab.h>
	#include <linux/sort.h>
	#include <asm/cacheflush.h>
	#include <asm/nospec-branch.h>
	#include <asm/pgalloc.h>
	#include <asm/setup.h>
	#include <asm/tlbflush.h>
	#include <asm/sections.h>
	#include <asm/set_memory.h>

	static DEFINE_MUTEX(vmem_mutex);

	static void __ref *vmem_alloc_pages(unsigned int order)
	{
	unsigned long size = PAGE_SIZE << order;

	if (slab_is_available())
	return (void *)__get_free_pages(GFP_KERNEL, order);
	return memblock_alloc(size, size);
	}

	static void vmem_free_pages(unsigned long addr, int order)
	{
	/* We don't expect boot memory to be removed ever. */
	if (!slab_is_available() \|\|
	WARN_ON_ONCE(PageReserved(virt_to_page((void *)addr))))
	return;
	free_pages(addr, order);
	}

	void *vmem_crst_alloc(unsigned long val)
	{
	unsigned long *table;

	table = vmem_alloc_pages(CRST_ALLOC_ORDER);
	if (table)
	crst_table_init(table, val);
	return table;
	}

	pte_t __ref *vmem_pte_alloc(void)
	{
	unsigned long size = PTRS_PER_PTE * sizeof(pte_t);
	pte_t *pte;

	if (slab_is_available())
	pte = (pte_t *) page_table_alloc(&init_mm);
	else
	pte = (pte_t *) memblock_alloc(size, size);
	if (!pte)
	return NULL;
	memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
	return pte;
	}

	static void vmem_pte_free(unsigned long *table)
	{
	/* We don't expect boot memory to be removed ever. */
	if (!slab_is_available() \|\|
	WARN_ON_ONCE(PageReserved(virt_to_page(table))))
	return;
	page_table_free(&init_mm, table);
	}

	#define PAGE_UNUSED 0xFD

	/*
	* The unused vmemmap range, which was not yet memset(PAGE_UNUSED) ranges
	* from unused_sub_pmd_start to next PMD_SIZE boundary.
	*/
	static unsigned long unused_sub_pmd_start;

	static void vmemmap_flush_unused_sub_pmd(void)
	{
	if (!unused_sub_pmd_start)
	return;
	memset((void *)unused_sub_pmd_start, PAGE_UNUSED,
	ALIGN(unused_sub_pmd_start, PMD_SIZE) - unused_sub_pmd_start);
	unused_sub_pmd_start = 0;
	}

	static void vmemmap_mark_sub_pmd_used(unsigned long start, unsigned long end)
	{
	/*
	* As we expect to add in the same granularity as we remove, it's
	* sufficient to mark only some piece used to block the memmap page from
	* getting removed (just in case the memmap never gets initialized,
	* e.g., because the memory block never gets onlined).
	*/
	memset((void *)start, 0, sizeof(struct page));
	}

	static void vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
	{
	/*
	* We only optimize if the new used range directly follows the
	* previously unused range (esp., when populating consecutive sections).
	*/
	if (unused_sub_pmd_start == start) {
	unused_sub_pmd_start = end;
	if (likely(IS_ALIGNED(unused_sub_pmd_start, PMD_SIZE)))
	unused_sub_pmd_start = 0;
	return;
	}
	vmemmap_flush_unused_sub_pmd();
	vmemmap_mark_sub_pmd_used(start, end);
	}

	static void vmemmap_use_new_sub_pmd(unsigned long start, unsigned long end)
	{
	unsigned long page = ALIGN_DOWN(start, PMD_SIZE);

	vmemmap_flush_unused_sub_pmd();

	/* Could be our memmap page is filled with PAGE_UNUSED already ... */
	vmemmap_mark_sub_pmd_used(start, end);

	/* Mark the unused parts of the new memmap page PAGE_UNUSED. */
	if (!IS_ALIGNED(start, PMD_SIZE))
	memset((void *)page, PAGE_UNUSED, start - page);
	/*
	* We want to avoid memset(PAGE_UNUSED) when populating the vmemmap of
	* consecutive sections. Remember for the last added PMD the last
	* unused range in the populated PMD.
	*/
	if (!IS_ALIGNED(end, PMD_SIZE))
	unused_sub_pmd_start = end;
	}

	/* Returns true if the PMD is completely unused and can be freed. */
	static bool vmemmap_unuse_sub_pmd(unsigned long start, unsigned long end)
	{
	unsigned long page = ALIGN_DOWN(start, PMD_SIZE);

	vmemmap_flush_unused_sub_pmd();
	memset((void *)start, PAGE_UNUSED, end - start);
	return !memchr_inv((void *)page, PAGE_UNUSED, PMD_SIZE);
	}

	/* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
	static int __ref modify_pte_table(pmd_t *pmd, unsigned long addr,
	unsigned long end, bool add, bool direct)
	{
	unsigned long prot, pages = 0;
	int ret = -ENOMEM;
	pte_t *pte;

	prot = pgprot_val(PAGE_KERNEL);
	if (!MACHINE_HAS_NX)
	prot &= ~_PAGE_NOEXEC;

	pte = pte_offset_kernel(pmd, addr);
	for (; addr < end; addr += PAGE_SIZE, pte++) {
	if (!add) {
	if (pte_none(*pte))
	continue;
	if (!direct)
	vmem_free_pages((unsigned long) pfn_to_virt(pte_pfn(*pte)), 0);
	pte_clear(&init_mm, addr, pte);
	} else if (pte_none(*pte)) {
	if (!direct) {
	void *new_page = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);

	if (!new_page)
	goto out;
	set_pte(pte, __pte(__pa(new_page) \| prot));
	} else {
	set_pte(pte, __pte(__pa(addr) \| prot));
	}
	} else {
	continue;
	}
	pages++;
	}
	ret = 0;
	out:
	if (direct)
	update_page_count(PG_DIRECT_MAP_4K, add ? pages : -pages);
	return ret;
	}

	static void try_free_pte_table(pmd_t *pmd, unsigned long start)
	{
	pte_t *pte;
	int i;

	/* We can safely assume this is fully in 1:1 mapping & vmemmap area */
	pte = pte_offset_kernel(pmd, start);
	for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
	if (!pte_none(*pte))
	return;
	}
	vmem_pte_free((unsigned long ) pmd_deref(pmd));
	pmd_clear(pmd);
	}

	/* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
	static int __ref modify_pmd_table(pud_t *pud, unsigned long addr,
	unsigned long end, bool add, bool direct)
	{
	unsigned long next, prot, pages = 0;
	int ret = -ENOMEM;
	pmd_t *pmd;
	pte_t *pte;

	prot = pgprot_val(SEGMENT_KERNEL);
	if (!MACHINE_HAS_NX)
	prot &= ~_SEGMENT_ENTRY_NOEXEC;

	pmd = pmd_offset(pud, addr);
	for (; addr < end; addr = next, pmd++) {
	next = pmd_addr_end(addr, end);
	if (!add) {
	if (pmd_none(*pmd))
	continue;
	if (pmd_large(*pmd)) {
	if (IS_ALIGNED(addr, PMD_SIZE) &&
	IS_ALIGNED(next, PMD_SIZE)) {
	if (!direct)
	vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE));
	pmd_clear(pmd);
	pages++;
	} else if (!direct && vmemmap_unuse_sub_pmd(addr, next)) {
	vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE));
	pmd_clear(pmd);
	}
	continue;
	}
	} else if (pmd_none(*pmd)) {
	if (IS_ALIGNED(addr, PMD_SIZE) &&
	IS_ALIGNED(next, PMD_SIZE) &&
	MACHINE_HAS_EDAT1 && direct &&
	!debug_pagealloc_enabled()) {
	set_pmd(pmd, __pmd(__pa(addr) \| prot));
	pages++;
	continue;
	} else if (!direct && MACHINE_HAS_EDAT1) {
	void *new_page;

	/*
	* Use 1MB frames for vmemmap if available. We
	* always use large frames even if they are only
	* partially used. Otherwise we would have also
	* page tables since vmemmap_populate gets
	* called for each section separately.
	*/
	new_page = vmemmap_alloc_block(PMD_SIZE, NUMA_NO_NODE);
	if (new_page) {
	set_pmd(pmd, __pmd(__pa(new_page) \| prot));
	if (!IS_ALIGNED(addr, PMD_SIZE) \|\|
	!IS_ALIGNED(next, PMD_SIZE)) {
	vmemmap_use_new_sub_pmd(addr, next);
	}
	continue;
	}
	}
	pte = vmem_pte_alloc();
	if (!pte)
	goto out;
	pmd_populate(&init_mm, pmd, pte);
	} else if (pmd_large(*pmd)) {
	if (!direct)
	vmemmap_use_sub_pmd(addr, next);
	continue;
	}
	ret = modify_pte_table(pmd, addr, next, add, direct);
	if (ret)
	goto out;
	if (!add)
	try_free_pte_table(pmd, addr & PMD_MASK);
	}
	ret = 0;
	out:
	if (direct)
	update_page_count(PG_DIRECT_MAP_1M, add ? pages : -pages);
	return ret;
	}

	static void try_free_pmd_table(pud_t *pud, unsigned long start)
	{
	pmd_t *pmd;
	int i;

	pmd = pmd_offset(pud, start);
	for (i = 0; i < PTRS_PER_PMD; i++, pmd++)
	if (!pmd_none(*pmd))
	return;
	vmem_free_pages(pud_deref(*pud), CRST_ALLOC_ORDER);
	pud_clear(pud);
	}

	static int modify_pud_table(p4d_t *p4d, unsigned long addr, unsigned long end,
	bool add, bool direct)
	{
	unsigned long next, prot, pages = 0;
	int ret = -ENOMEM;
	pud_t *pud;
	pmd_t *pmd;

	prot = pgprot_val(REGION3_KERNEL);
	if (!MACHINE_HAS_NX)
	prot &= ~_REGION_ENTRY_NOEXEC;
	pud = pud_offset(p4d, addr);
	for (; addr < end; addr = next, pud++) {
	next = pud_addr_end(addr, end);
	if (!add) {
	if (pud_none(*pud))
	continue;
	if (pud_large(*pud)) {
	if (IS_ALIGNED(addr, PUD_SIZE) &&
	IS_ALIGNED(next, PUD_SIZE)) {
	pud_clear(pud);
	pages++;
	}
	continue;
	}
	} else if (pud_none(*pud)) {
	if (IS_ALIGNED(addr, PUD_SIZE) &&
	IS_ALIGNED(next, PUD_SIZE) &&
	MACHINE_HAS_EDAT2 && direct &&
	!debug_pagealloc_enabled()) {
	set_pud(pud, __pud(__pa(addr) \| prot));
	pages++;
	continue;
	}
	pmd = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
	if (!pmd)
	goto out;
	pud_populate(&init_mm, pud, pmd);
	} else if (pud_large(*pud)) {
	continue;
	}
	ret = modify_pmd_table(pud, addr, next, add, direct);
	if (ret)
	goto out;
	if (!add)
	try_free_pmd_table(pud, addr & PUD_MASK);
	}
	ret = 0;
	out:
	if (direct)
	update_page_count(PG_DIRECT_MAP_2G, add ? pages : -pages);
	return ret;
	}

	static void try_free_pud_table(p4d_t *p4d, unsigned long start)
	{
	pud_t *pud;
	int i;

	pud = pud_offset(p4d, start);
	for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
	if (!pud_none(*pud))
	return;
	}
	vmem_free_pages(p4d_deref(*p4d), CRST_ALLOC_ORDER);
	p4d_clear(p4d);
	}

	static int modify_p4d_table(pgd_t *pgd, unsigned long addr, unsigned long end,
	bool add, bool direct)
	{
	unsigned long next;
	int ret = -ENOMEM;
	p4d_t *p4d;
	pud_t *pud;

	p4d = p4d_offset(pgd, addr);
	for (; addr < end; addr = next, p4d++) {
	next = p4d_addr_end(addr, end);
	if (!add) {
	if (p4d_none(*p4d))
	continue;
	} else if (p4d_none(*p4d)) {
	pud = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
	if (!pud)
	goto out;
	p4d_populate(&init_mm, p4d, pud);
	}
	ret = modify_pud_table(p4d, addr, next, add, direct);
	if (ret)
	goto out;
	if (!add)
	try_free_pud_table(p4d, addr & P4D_MASK);
	}
	ret = 0;
	out:
	return ret;
	}

	static void try_free_p4d_table(pgd_t *pgd, unsigned long start)
	{
	p4d_t *p4d;
	int i;

	p4d = p4d_offset(pgd, start);
	for (i = 0; i < PTRS_PER_P4D; i++, p4d++) {
	if (!p4d_none(*p4d))
	return;
	}
	vmem_free_pages(pgd_deref(*pgd), CRST_ALLOC_ORDER);
	pgd_clear(pgd);
	}

	static int modify_pagetable(unsigned long start, unsigned long end, bool add,
	bool direct)
	{
	unsigned long addr, next;
	int ret = -ENOMEM;
	pgd_t *pgd;
	p4d_t *p4d;

	if (WARN_ON_ONCE(!PAGE_ALIGNED(start \| end)))
	return -EINVAL;
	/* Don't mess with any tables not fully in 1:1 mapping & vmemmap area */
	if (WARN_ON_ONCE(end > VMALLOC_START))
	return -EINVAL;
	for (addr = start; addr < end; addr = next) {
	next = pgd_addr_end(addr, end);
	pgd = pgd_offset_k(addr);

	if (!add) {
	if (pgd_none(*pgd))
	continue;
	} else if (pgd_none(*pgd)) {
	p4d = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
	if (!p4d)
	goto out;
	pgd_populate(&init_mm, pgd, p4d);
	}
	ret = modify_p4d_table(pgd, addr, next, add, direct);
	if (ret)
	goto out;
	if (!add)
	try_free_p4d_table(pgd, addr & PGDIR_MASK);
	}
	ret = 0;
	out:
	if (!add)
	flush_tlb_kernel_range(start, end);
	return ret;
	}

	static int add_pagetable(unsigned long start, unsigned long end, bool direct)
	{
	return modify_pagetable(start, end, true, direct);
	}

	static int remove_pagetable(unsigned long start, unsigned long end, bool direct)
	{
	return modify_pagetable(start, end, false, direct);
	}

	/*
	* Add a physical memory range to the 1:1 mapping.
	*/
	static int vmem_add_range(unsigned long start, unsigned long size)
	{
	start = (unsigned long)__va(start);
	return add_pagetable(start, start + size, true);
	}

	/*
	* Remove a physical memory range from the 1:1 mapping.
	*/
	static void vmem_remove_range(unsigned long start, unsigned long size)
	{
	start = (unsigned long)__va(start);
	remove_pagetable(start, start + size, true);
	}

	/*
	* Add a backed mem_map array to the virtual mem_map array.
	*/
	int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
	struct vmem_altmap *altmap)
	{
	int ret;

	mutex_lock(&vmem_mutex);
	/* We don't care about the node, just use NUMA_NO_NODE on allocations */
	ret = add_pagetable(start, end, false);
	if (ret)
	remove_pagetable(start, end, false);
	mutex_unlock(&vmem_mutex);
	return ret;
	}

	void vmemmap_free(unsigned long start, unsigned long end,
	struct vmem_altmap *altmap)
	{
	mutex_lock(&vmem_mutex);
	remove_pagetable(start, end, false);
	mutex_unlock(&vmem_mutex);
	}

	void vmem_remove_mapping(unsigned long start, unsigned long size)
	{
	mutex_lock(&vmem_mutex);
	vmem_remove_range(start, size);
	mutex_unlock(&vmem_mutex);
	}

	struct range arch_get_mappable_range(void)
	{
	struct range mhp_range;

	mhp_range.start = 0;
	mhp_range.end = max_mappable - 1;
	return mhp_range;
	}

	int vmem_add_mapping(unsigned long start, unsigned long size)
	{
	struct range range = arch_get_mappable_range();
	int ret;

	if (start < range.start \|\|
	start + size > range.end + 1 \|\|
	start + size < start)
	return -ERANGE;

	mutex_lock(&vmem_mutex);
	ret = vmem_add_range(start, size);
	if (ret)
	vmem_remove_range(start, size);
	mutex_unlock(&vmem_mutex);
	return ret;
	}

	/*
	* Allocate new or return existing page-table entry, but do not map it
	* to any physical address. If missing, allocate segment- and region-
	* table entries along. Meeting a large segment- or region-table entry
	* while traversing is an error, since the function is expected to be
	* called against virtual regions reserved for 4KB mappings only.
	*/
	pte_t *vmem_get_alloc_pte(unsigned long addr, bool alloc)
	{
	pte_t *ptep = NULL;
	pgd_t *pgd;
	p4d_t *p4d;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	pgd = pgd_offset_k(addr);
	if (pgd_none(*pgd)) {
	if (!alloc)
	goto out;
	p4d = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
	if (!p4d)
	goto out;
	pgd_populate(&init_mm, pgd, p4d);
	}
	p4d = p4d_offset(pgd, addr);
	if (p4d_none(*p4d)) {
	if (!alloc)
	goto out;
	pud = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
	if (!pud)
	goto out;
	p4d_populate(&init_mm, p4d, pud);
	}
	pud = pud_offset(p4d, addr);
	if (pud_none(*pud)) {
	if (!alloc)
	goto out;
	pmd = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
	if (!pmd)
	goto out;
	pud_populate(&init_mm, pud, pmd);
	} else if (WARN_ON_ONCE(pud_large(*pud))) {
	goto out;
	}
	pmd = pmd_offset(pud, addr);
	if (pmd_none(*pmd)) {
	if (!alloc)
	goto out;
	pte = vmem_pte_alloc();
	if (!pte)
	goto out;
	pmd_populate(&init_mm, pmd, pte);
	} else if (WARN_ON_ONCE(pmd_large(*pmd))) {
	goto out;
	}
	ptep = pte_offset_kernel(pmd, addr);
	out:
	return ptep;
	}

	int __vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot, bool alloc)
	{
	pte_t *ptep, pte;

	if (!IS_ALIGNED(addr, PAGE_SIZE))
	return -EINVAL;
	ptep = vmem_get_alloc_pte(addr, alloc);
	if (!ptep)
	return -ENOMEM;
	__ptep_ipte(addr, ptep, 0, 0, IPTE_GLOBAL);
	pte = mk_pte_phys(phys, prot);
	set_pte(ptep, pte);
	return 0;
	}

	int vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot)
	{
	int rc;

	mutex_lock(&vmem_mutex);
	rc = __vmem_map_4k_page(addr, phys, prot, true);
	mutex_unlock(&vmem_mutex);
	return rc;
	}

	void vmem_unmap_4k_page(unsigned long addr)
	{
	pte_t *ptep;

	mutex_lock(&vmem_mutex);
	ptep = virt_to_kpte(addr);
	__ptep_ipte(addr, ptep, 0, 0, IPTE_GLOBAL);
	pte_clear(&init_mm, addr, ptep);
	mutex_unlock(&vmem_mutex);
	}

	void __init vmem_map_init(void)
	{
	__set_memory_rox(_stext, _etext);
	__set_memory_ro(_etext, __end_rodata);
	__set_memory_rox(_sinittext, _einittext);
	__set_memory_rox(__stext_amode31, __etext_amode31);
	/*
	* If the BEAR-enhancement facility is not installed the first
	* prefix page is used to return to the previous context with
	* an LPSWE instruction and therefore must be executable.
	*/
	if (!static_key_enabled(&cpu_has_bear))
	set_memory_x(0, 1);
	if (debug_pagealloc_enabled()) {
	/*
	* Use RELOC_HIDE() as long as __va(0) translates to NULL,
	* since performing pointer arithmetic on a NULL pointer
	* has undefined behavior and generates compiler warnings.
	*/
	__set_memory_4k(__va(0), RELOC_HIDE(__va(0), ident_map_size));
	}
	if (MACHINE_HAS_NX)
	ctl_set_bit(0, 20);
	pr_info("Write protected kernel read-only data: %luk\n",
	(unsigned long)(__end_rodata - _stext) >> 10);
	}