arch/powerpc/mm/init_64.c - kernel/msm-4.9 - Gitiles

 /*
  *  PowerPC version
  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
  *
  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
  *    Copyright (C) 1996 Paul Mackerras
  *
  *  Derived from "arch/i386/mm/init.c"
  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  *
  *  Dave Engebretsen <engebret@us.ibm.com>
  *      Rework for PPC64 port.
  *
  *  This program is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU General Public License
  *  as published by the Free Software Foundation; either version
  *  2 of the License, or (at your option) any later version.
  *
  */

 #undef DEBUG

 #include <linux/signal.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/mman.h>
 #include <linux/mm.h>
 #include <linux/swap.h>
 #include <linux/stddef.h>
 #include <linux/vmalloc.h>
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/highmem.h>
 #include <linux/idr.h>
 #include <linux/nodemask.h>
 #include <linux/module.h>
 #include <linux/poison.h>
 #include <linux/memblock.h>
 #include <linux/hugetlb.h>
 #include <linux/slab.h>

 #include <asm/pgalloc.h>
 #include <asm/page.h>
 #include <asm/prom.h>
 #include <asm/rtas.h>
 #include <asm/io.h>
 #include <asm/mmu_context.h>
 #include <asm/pgtable.h>
 #include <asm/mmu.h>
 #include <asm/uaccess.h>
 #include <asm/smp.h>
 #include <asm/machdep.h>
 #include <asm/tlb.h>
 #include <asm/eeh.h>
 #include <asm/processor.h>
 #include <asm/mmzone.h>
 #include <asm/cputable.h>
 #include <asm/sections.h>
 #include <asm/iommu.h>
 #include <asm/vdso.h>

 #include "mmu_decl.h"

 #ifdef CONFIG_PPC_STD_MMU_64
 #if PGTABLE_RANGE > USER_VSID_RANGE
 #warning Limited user VSID range means pagetable space is wasted
 #endif

 #if (TASK_SIZE_USER64 < PGTABLE_RANGE) && (TASK_SIZE_USER64 < USER_VSID_RANGE)
 #warning TASK_SIZE is smaller than it needs to be.
 #endif
 #endif /* CONFIG_PPC_STD_MMU_64 */

 phys_addr_t memstart_addr = ~0;
 EXPORT_SYMBOL_GPL(memstart_addr);
 phys_addr_t kernstart_addr;
 EXPORT_SYMBOL_GPL(kernstart_addr);

 static void pgd_ctor(void *addr)
 {
 	memset(addr, 0, PGD_TABLE_SIZE);
 }

 static void pmd_ctor(void *addr)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	memset(addr, 0, PMD_TABLE_SIZE * 2);
 #else
 	memset(addr, 0, PMD_TABLE_SIZE);
 #endif
 }

 struct kmem_cache *pgtable_cache[MAX_PGTABLE_INDEX_SIZE];

 /*
  * Create a kmem_cache() for pagetables.  This is not used for PTE
  * pages - they're linked to struct page, come from the normal free
  * pages pool and have a different entry size (see real_pte_t) to
  * everything else.  Caches created by this function are used for all
  * the higher level pagetables, and for hugepage pagetables.
  */
 void pgtable_cache_add(unsigned shift, void (*ctor)(void *))
 {
 	char *name;
 	unsigned long table_size = sizeof(void *) << shift;
 	unsigned long align = table_size;

 	/* When batching pgtable pointers for RCU freeing, we store
 	 * the index size in the low bits.  Table alignment must be
 	 * big enough to fit it.
 	 *
 	 * Likewise, hugeapge pagetable pointers contain a (different)
 	 * shift value in the low bits.  All tables must be aligned so
 	 * as to leave enough 0 bits in the address to contain it. */
 	unsigned long minalign = max(MAX_PGTABLE_INDEX_SIZE + 1,
 				     HUGEPD_SHIFT_MASK + 1);
 	struct kmem_cache *new;

 	/* It would be nice if this was a BUILD_BUG_ON(), but at the
 	 * moment, gcc doesn't seem to recognize is_power_of_2 as a
 	 * constant expression, so so much for that. */
 	BUG_ON(!is_power_of_2(minalign));
 	BUG_ON((shift < 1) || (shift > MAX_PGTABLE_INDEX_SIZE));

 	if (PGT_CACHE(shift))
 		return; /* Already have a cache of this size */

 	align = max_t(unsigned long, align, minalign);
 	name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
 	new = kmem_cache_create(name, table_size, align, 0, ctor);
 	kfree(name);
 	pgtable_cache[shift - 1] = new;
 	pr_debug("Allocated pgtable cache for order %d\n", shift);
 }


 void pgtable_cache_init(void)
 {
 	pgtable_cache_add(PGD_INDEX_SIZE, pgd_ctor);
 	pgtable_cache_add(PMD_CACHE_INDEX, pmd_ctor);
 	if (!PGT_CACHE(PGD_INDEX_SIZE) || !PGT_CACHE(PMD_CACHE_INDEX))
 		panic("Couldn't allocate pgtable caches");
 	/* In all current configs, when the PUD index exists it's the
 	 * same size as either the pgd or pmd index.  Verify that the
 	 * initialization above has also created a PUD cache.  This
 	 * will need re-examiniation if we add new possibilities for
 	 * the pagetable layout. */
 	BUG_ON(PUD_INDEX_SIZE && !PGT_CACHE(PUD_INDEX_SIZE));
 }

 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 /*
  * Given an address within the vmemmap, determine the pfn of the page that
  * represents the start of the section it is within.  Note that we have to
  * do this by hand as the proffered address may not be correctly aligned.
  * Subtraction of non-aligned pointers produces undefined results.
  */
 static unsigned long __meminit vmemmap_section_start(unsigned long page)
 {
 	unsigned long offset = page - ((unsigned long)(vmemmap));

 	/* Return the pfn of the start of the section. */
 	return (offset / sizeof(struct page)) & PAGE_SECTION_MASK;
 }

 /*
  * Check if this vmemmap page is already initialised.  If any section
  * which overlaps this vmemmap page is initialised then this page is
  * initialised already.
  */
 static int __meminit vmemmap_populated(unsigned long start, int page_size)
 {
 	unsigned long end = start + page_size;
 	start = (unsigned long)(pfn_to_page(vmemmap_section_start(start)));

 	for (; start < end; start += (PAGES_PER_SECTION * sizeof(struct page)))
 		if (pfn_valid(page_to_pfn((struct page *)start)))
 			return 1;

 	return 0;
 }

 /* On hash-based CPUs, the vmemmap is bolted in the hash table.
  *
  * On Book3E CPUs, the vmemmap is currently mapped in the top half of
  * the vmalloc space using normal page tables, though the size of
  * pages encoded in the PTEs can be different
  */

 #ifdef CONFIG_PPC_BOOK3E
 static void __meminit vmemmap_create_mapping(unsigned long start,
 					     unsigned long page_size,
 					     unsigned long phys)
 {
 	/* Create a PTE encoding without page size */
 	unsigned long i, flags = _PAGE_PRESENT | _PAGE_ACCESSED |
 		_PAGE_KERNEL_RW;

 	/* PTEs only contain page size encodings up to 32M */
 	BUG_ON(mmu_psize_defs[mmu_vmemmap_psize].enc > 0xf);

 	/* Encode the size in the PTE */
 	flags |= mmu_psize_defs[mmu_vmemmap_psize].enc << 8;

 	/* For each PTE for that area, map things. Note that we don't
 	 * increment phys because all PTEs are of the large size and
 	 * thus must have the low bits clear
 	 */
 	for (i = 0; i < page_size; i += PAGE_SIZE)
 		BUG_ON(map_kernel_page(start + i, phys, flags));
 }

 #ifdef CONFIG_MEMORY_HOTPLUG
 static void vmemmap_remove_mapping(unsigned long start,
 				   unsigned long page_size)
 {
 }
 #endif
 #else /* CONFIG_PPC_BOOK3E */
 static void __meminit vmemmap_create_mapping(unsigned long start,
 					     unsigned long page_size,
 					     unsigned long phys)
 {
 	int  mapped = htab_bolt_mapping(start, start + page_size, phys,
 					pgprot_val(PAGE_KERNEL),
 					mmu_vmemmap_psize,
 					mmu_kernel_ssize);
 	BUG_ON(mapped < 0);
 }

 #ifdef CONFIG_MEMORY_HOTPLUG
 static void vmemmap_remove_mapping(unsigned long start,
 				   unsigned long page_size)
 {
 	int mapped = htab_remove_mapping(start, start + page_size,
 					 mmu_vmemmap_psize,
 					 mmu_kernel_ssize);
 	BUG_ON(mapped < 0);
 }
 #endif

 #endif /* CONFIG_PPC_BOOK3E */

 struct vmemmap_backing *vmemmap_list;
 static struct vmemmap_backing *next;
 static int num_left;
 static int num_freed;

 static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node)
 {
 	struct vmemmap_backing *vmem_back;
 	/* get from freed entries first */
 	if (num_freed) {
 		num_freed--;
 		vmem_back = next;
 		next = next->list;

 		return vmem_back;
 	}

 	/* allocate a page when required and hand out chunks */
 	if (!num_left) {
 		next = vmemmap_alloc_block(PAGE_SIZE, node);
 		if (unlikely(!next)) {
 			WARN_ON(1);
 			return NULL;
 		}
 		num_left = PAGE_SIZE / sizeof(struct vmemmap_backing);
 	}

 	num_left--;

 	return next++;
 }

 static __meminit void vmemmap_list_populate(unsigned long phys,
 					    unsigned long start,
 					    int node)
 {
 	struct vmemmap_backing *vmem_back;

 	vmem_back = vmemmap_list_alloc(node);
 	if (unlikely(!vmem_back)) {
 		WARN_ON(1);
 		return;
 	}

 	vmem_back->phys = phys;
 	vmem_back->virt_addr = start;
 	vmem_back->list = vmemmap_list;

 	vmemmap_list = vmem_back;
 }

 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
 {
 	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;

 	/* Align to the page size of the linear mapping. */
 	start = _ALIGN_DOWN(start, page_size);

 	pr_debug("vmemmap_populate %lx..%lx, node %d\n", start, end, node);

 	for (; start < end; start += page_size) {
 		void *p;

 		if (vmemmap_populated(start, page_size))
 			continue;

 		p = vmemmap_alloc_block(page_size, node);
 		if (!p)
 			return -ENOMEM;

 		vmemmap_list_populate(__pa(p), start, node);

 		pr_debug("      * %016lx..%016lx allocated at %p\n",
 			 start, start + page_size, p);

 		vmemmap_create_mapping(start, page_size, __pa(p));
 	}

 	return 0;
 }

 #ifdef CONFIG_MEMORY_HOTPLUG
 static unsigned long vmemmap_list_free(unsigned long start)
 {
 	struct vmemmap_backing *vmem_back, *vmem_back_prev;

 	vmem_back_prev = vmem_back = vmemmap_list;

 	/* look for it with prev pointer recorded */
 	for (; vmem_back; vmem_back = vmem_back->list) {
 		if (vmem_back->virt_addr == start)
 			break;
 		vmem_back_prev = vmem_back;
 	}

 	if (unlikely(!vmem_back)) {
 		WARN_ON(1);
 		return 0;
 	}

 	/* remove it from vmemmap_list */
 	if (vmem_back == vmemmap_list) /* remove head */
 		vmemmap_list = vmem_back->list;
 	else
 		vmem_back_prev->list = vmem_back->list;

 	/* next point to this freed entry */
 	vmem_back->list = next;
 	next = vmem_back;
 	num_freed++;

 	return vmem_back->phys;
 }

 void __ref vmemmap_free(unsigned long start, unsigned long end)
 {
 	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;

 	start = _ALIGN_DOWN(start, page_size);

 	pr_debug("vmemmap_free %lx...%lx\n", start, end);

 	for (; start < end; start += page_size) {
 		unsigned long addr;

 		/*
 		 * the section has already be marked as invalid, so
 		 * vmemmap_populated() true means some other sections still
 		 * in this page, so skip it.
 		 */
 		if (vmemmap_populated(start, page_size))
 			continue;

 		addr = vmemmap_list_free(start);
 		if (addr) {
 			struct page *page = pfn_to_page(addr >> PAGE_SHIFT);

 			if (PageReserved(page)) {
 				/* allocated from bootmem */
 				if (page_size < PAGE_SIZE) {
 					/*
 					 * this shouldn't happen, but if it is
 					 * the case, leave the memory there
 					 */
 					WARN_ON_ONCE(1);
 				} else {
 					unsigned int nr_pages =
 						1 << get_order(page_size);
 					while (nr_pages--)
 						free_reserved_page(page++);
 				}
 			} else
 				free_pages((unsigned long)(__va(addr)),
 							get_order(page_size));

 			vmemmap_remove_mapping(start, page_size);
 		}
 	}
 }
 #endif
 void register_page_bootmem_memmap(unsigned long section_nr,
 				  struct page *start_page, unsigned long size)
 {
 }

 /*
  * We do not have access to the sparsemem vmemmap, so we fallback to
  * walking the list of sparsemem blocks which we already maintain for
  * the sake of crashdump. In the long run, we might want to maintain
  * a tree if performance of that linear walk becomes a problem.
  *
  * realmode_pfn_to_page functions can fail due to:
  * 1) As real sparsemem blocks do not lay in RAM continously (they
  * are in virtual address space which is not available in the real mode),
  * the requested page struct can be split between blocks so get_page/put_page
  * may fail.
  * 2) When huge pages are used, the get_page/put_page API will fail
  * in real mode as the linked addresses in the page struct are virtual
  * too.
  */
 struct page *realmode_pfn_to_page(unsigned long pfn)
 {
 	struct vmemmap_backing *vmem_back;
 	struct page *page;
 	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
 	unsigned long pg_va = (unsigned long) pfn_to_page(pfn);

 	for (vmem_back = vmemmap_list; vmem_back; vmem_back = vmem_back->list) {
 		if (pg_va < vmem_back->virt_addr)
 			continue;

 		/* After vmemmap_list entry free is possible, need check all */
 		if ((pg_va + sizeof(struct page)) <=
 				(vmem_back->virt_addr + page_size)) {
 			page = (struct page *) (vmem_back->phys + pg_va -
 				vmem_back->virt_addr);
 			return page;
 		}
 	}

 	/* Probably that page struct is split between real pages */
 	return NULL;
 }
 EXPORT_SYMBOL_GPL(realmode_pfn_to_page);

 #elif defined(CONFIG_FLATMEM)

 struct page *realmode_pfn_to_page(unsigned long pfn)
 {
 	struct page *page = pfn_to_page(pfn);
 	return page;
 }
 EXPORT_SYMBOL_GPL(realmode_pfn_to_page);

 #endif /* CONFIG_SPARSEMEM_VMEMMAP/CONFIG_FLATMEM */
	/*
	* PowerPC version
	* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
	*
	* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
	* and Cort Dougan (PReP) (cort@cs.nmt.edu)
	* Copyright (C) 1996 Paul Mackerras
	*
	* Derived from "arch/i386/mm/init.c"
	* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
	*
	* Dave Engebretsen <engebret@us.ibm.com>
	* Rework for PPC64 port.
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*
	*/

	#undef DEBUG

	#include <linux/signal.h>
	#include <linux/sched.h>
	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/string.h>
	#include <linux/types.h>
	#include <linux/mman.h>
	#include <linux/mm.h>
	#include <linux/swap.h>
	#include <linux/stddef.h>
	#include <linux/vmalloc.h>
	#include <linux/init.h>
	#include <linux/delay.h>
	#include <linux/highmem.h>
	#include <linux/idr.h>
	#include <linux/nodemask.h>
	#include <linux/module.h>
	#include <linux/poison.h>
	#include <linux/memblock.h>
	#include <linux/hugetlb.h>
	#include <linux/slab.h>

	#include <asm/pgalloc.h>
	#include <asm/page.h>
	#include <asm/prom.h>
	#include <asm/rtas.h>
	#include <asm/io.h>
	#include <asm/mmu_context.h>
	#include <asm/pgtable.h>
	#include <asm/mmu.h>
	#include <asm/uaccess.h>
	#include <asm/smp.h>
	#include <asm/machdep.h>
	#include <asm/tlb.h>
	#include <asm/eeh.h>
	#include <asm/processor.h>
	#include <asm/mmzone.h>
	#include <asm/cputable.h>
	#include <asm/sections.h>
	#include <asm/iommu.h>
	#include <asm/vdso.h>

	#include "mmu_decl.h"

	#ifdef CONFIG_PPC_STD_MMU_64
	#if PGTABLE_RANGE > USER_VSID_RANGE
	#warning Limited user VSID range means pagetable space is wasted
	#endif

	#if (TASK_SIZE_USER64 < PGTABLE_RANGE) && (TASK_SIZE_USER64 < USER_VSID_RANGE)
	#warning TASK_SIZE is smaller than it needs to be.
	#endif
	#endif /* CONFIG_PPC_STD_MMU_64 */

	phys_addr_t memstart_addr = ~0;
	EXPORT_SYMBOL_GPL(memstart_addr);
	phys_addr_t kernstart_addr;
	EXPORT_SYMBOL_GPL(kernstart_addr);

	static void pgd_ctor(void *addr)
	{
	memset(addr, 0, PGD_TABLE_SIZE);
	}

	static void pmd_ctor(void *addr)
	{
	#ifdef CONFIG_TRANSPARENT_HUGEPAGE
	memset(addr, 0, PMD_TABLE_SIZE * 2);
	#else
	memset(addr, 0, PMD_TABLE_SIZE);
	#endif
	}

	struct kmem_cache *pgtable_cache[MAX_PGTABLE_INDEX_SIZE];

	/*
	* Create a kmem_cache() for pagetables. This is not used for PTE
	* pages - they're linked to struct page, come from the normal free
	* pages pool and have a different entry size (see real_pte_t) to
	* everything else. Caches created by this function are used for all
	* the higher level pagetables, and for hugepage pagetables.
	*/
	void pgtable_cache_add(unsigned shift, void (ctor)(void ))
	{
	char *name;
	unsigned long table_size = sizeof(void *) << shift;
	unsigned long align = table_size;

	/* When batching pgtable pointers for RCU freeing, we store
	* the index size in the low bits. Table alignment must be
	* big enough to fit it.
	*
	* Likewise, hugeapge pagetable pointers contain a (different)
	* shift value in the low bits. All tables must be aligned so
	* as to leave enough 0 bits in the address to contain it. */
	unsigned long minalign = max(MAX_PGTABLE_INDEX_SIZE + 1,
	HUGEPD_SHIFT_MASK + 1);
	struct kmem_cache *new;

	/* It would be nice if this was a BUILD_BUG_ON(), but at the
	* moment, gcc doesn't seem to recognize is_power_of_2 as a
	* constant expression, so so much for that. */
	BUG_ON(!is_power_of_2(minalign));
	BUG_ON((shift < 1) \|\| (shift > MAX_PGTABLE_INDEX_SIZE));

	if (PGT_CACHE(shift))
	return; /* Already have a cache of this size */

	align = max_t(unsigned long, align, minalign);
	name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
	new = kmem_cache_create(name, table_size, align, 0, ctor);
	kfree(name);
	pgtable_cache[shift - 1] = new;
	pr_debug("Allocated pgtable cache for order %d\n", shift);
	}


	void pgtable_cache_init(void)
	{
	pgtable_cache_add(PGD_INDEX_SIZE, pgd_ctor);
	pgtable_cache_add(PMD_CACHE_INDEX, pmd_ctor);
	if (!PGT_CACHE(PGD_INDEX_SIZE) \|\| !PGT_CACHE(PMD_CACHE_INDEX))
	panic("Couldn't allocate pgtable caches");
	/* In all current configs, when the PUD index exists it's the
	* same size as either the pgd or pmd index. Verify that the
	* initialization above has also created a PUD cache. This
	* will need re-examiniation if we add new possibilities for
	* the pagetable layout. */
	BUG_ON(PUD_INDEX_SIZE && !PGT_CACHE(PUD_INDEX_SIZE));
	}

	#ifdef CONFIG_SPARSEMEM_VMEMMAP
	/*
	* Given an address within the vmemmap, determine the pfn of the page that
	* represents the start of the section it is within. Note that we have to
	* do this by hand as the proffered address may not be correctly aligned.
	* Subtraction of non-aligned pointers produces undefined results.
	*/
	static unsigned long __meminit vmemmap_section_start(unsigned long page)
	{
	unsigned long offset = page - ((unsigned long)(vmemmap));

	/* Return the pfn of the start of the section. */
	return (offset / sizeof(struct page)) & PAGE_SECTION_MASK;
	}

	/*
	* Check if this vmemmap page is already initialised. If any section
	* which overlaps this vmemmap page is initialised then this page is
	* initialised already.
	*/
	static int __meminit vmemmap_populated(unsigned long start, int page_size)
	{
	unsigned long end = start + page_size;
	start = (unsigned long)(pfn_to_page(vmemmap_section_start(start)));

	for (; start < end; start += (PAGES_PER_SECTION * sizeof(struct page)))
	if (pfn_valid(page_to_pfn((struct page *)start)))
	return 1;

	return 0;
	}

	/* On hash-based CPUs, the vmemmap is bolted in the hash table.
	*
	* On Book3E CPUs, the vmemmap is currently mapped in the top half of
	* the vmalloc space using normal page tables, though the size of
	* pages encoded in the PTEs can be different
	*/

	#ifdef CONFIG_PPC_BOOK3E
	static void __meminit vmemmap_create_mapping(unsigned long start,
	unsigned long page_size,
	unsigned long phys)
	{
	/* Create a PTE encoding without page size */
	unsigned long i, flags = _PAGE_PRESENT \| _PAGE_ACCESSED \|
	_PAGE_KERNEL_RW;

	/* PTEs only contain page size encodings up to 32M */
	BUG_ON(mmu_psize_defs[mmu_vmemmap_psize].enc > 0xf);

	/* Encode the size in the PTE */
	flags \|= mmu_psize_defs[mmu_vmemmap_psize].enc << 8;

	/* For each PTE for that area, map things. Note that we don't
	* increment phys because all PTEs are of the large size and
	* thus must have the low bits clear
	*/
	for (i = 0; i < page_size; i += PAGE_SIZE)
	BUG_ON(map_kernel_page(start + i, phys, flags));
	}

	#ifdef CONFIG_MEMORY_HOTPLUG
	static void vmemmap_remove_mapping(unsigned long start,
	unsigned long page_size)
	{
	}
	#endif
	#else /* CONFIG_PPC_BOOK3E */
	static void __meminit vmemmap_create_mapping(unsigned long start,
	unsigned long page_size,
	unsigned long phys)
	{
	int mapped = htab_bolt_mapping(start, start + page_size, phys,
	pgprot_val(PAGE_KERNEL),
	mmu_vmemmap_psize,
	mmu_kernel_ssize);
	BUG_ON(mapped < 0);
	}

	#ifdef CONFIG_MEMORY_HOTPLUG
	static void vmemmap_remove_mapping(unsigned long start,
	unsigned long page_size)
	{
	int mapped = htab_remove_mapping(start, start + page_size,
	mmu_vmemmap_psize,
	mmu_kernel_ssize);
	BUG_ON(mapped < 0);
	}
	#endif

	#endif /* CONFIG_PPC_BOOK3E */

	struct vmemmap_backing *vmemmap_list;
	static struct vmemmap_backing *next;
	static int num_left;
	static int num_freed;

	static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node)
	{
	struct vmemmap_backing *vmem_back;
	/* get from freed entries first */
	if (num_freed) {
	num_freed--;
	vmem_back = next;
	next = next->list;

	return vmem_back;
	}

	/* allocate a page when required and hand out chunks */
	if (!num_left) {
	next = vmemmap_alloc_block(PAGE_SIZE, node);
	if (unlikely(!next)) {
	WARN_ON(1);
	return NULL;
	}
	num_left = PAGE_SIZE / sizeof(struct vmemmap_backing);
	}

	num_left--;

	return next++;
	}

	static __meminit void vmemmap_list_populate(unsigned long phys,
	unsigned long start,
	int node)
	{
	struct vmemmap_backing *vmem_back;

	vmem_back = vmemmap_list_alloc(node);
	if (unlikely(!vmem_back)) {
	WARN_ON(1);
	return;
	}

	vmem_back->phys = phys;
	vmem_back->virt_addr = start;
	vmem_back->list = vmemmap_list;

	vmemmap_list = vmem_back;
	}

	int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
	{
	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;

	/* Align to the page size of the linear mapping. */
	start = _ALIGN_DOWN(start, page_size);

	pr_debug("vmemmap_populate %lx..%lx, node %d\n", start, end, node);

	for (; start < end; start += page_size) {
	void *p;

	if (vmemmap_populated(start, page_size))
	continue;

	p = vmemmap_alloc_block(page_size, node);
	if (!p)
	return -ENOMEM;

	vmemmap_list_populate(__pa(p), start, node);

	pr_debug(" * %016lx..%016lx allocated at %p\n",
	start, start + page_size, p);

	vmemmap_create_mapping(start, page_size, __pa(p));
	}

	return 0;
	}

	#ifdef CONFIG_MEMORY_HOTPLUG
	static unsigned long vmemmap_list_free(unsigned long start)
	{
	struct vmemmap_backing vmem_back, vmem_back_prev;

	vmem_back_prev = vmem_back = vmemmap_list;

	/* look for it with prev pointer recorded */
	for (; vmem_back; vmem_back = vmem_back->list) {
	if (vmem_back->virt_addr == start)
	break;
	vmem_back_prev = vmem_back;
	}

	if (unlikely(!vmem_back)) {
	WARN_ON(1);
	return 0;
	}

	/* remove it from vmemmap_list */
	if (vmem_back == vmemmap_list) /* remove head */
	vmemmap_list = vmem_back->list;
	else
	vmem_back_prev->list = vmem_back->list;

	/* next point to this freed entry */
	vmem_back->list = next;
	next = vmem_back;
	num_freed++;

	return vmem_back->phys;
	}

	void __ref vmemmap_free(unsigned long start, unsigned long end)
	{
	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;

	start = _ALIGN_DOWN(start, page_size);

	pr_debug("vmemmap_free %lx...%lx\n", start, end);

	for (; start < end; start += page_size) {
	unsigned long addr;

	/*
	* the section has already be marked as invalid, so
	* vmemmap_populated() true means some other sections still
	* in this page, so skip it.
	*/
	if (vmemmap_populated(start, page_size))
	continue;

	addr = vmemmap_list_free(start);
	if (addr) {
	struct page *page = pfn_to_page(addr >> PAGE_SHIFT);

	if (PageReserved(page)) {
	/* allocated from bootmem */
	if (page_size < PAGE_SIZE) {
	/*
	* this shouldn't happen, but if it is
	* the case, leave the memory there
	*/
	WARN_ON_ONCE(1);
	} else {
	unsigned int nr_pages =
	1 << get_order(page_size);
	while (nr_pages--)
	free_reserved_page(page++);
	}
	} else
	free_pages((unsigned long)(__va(addr)),
	get_order(page_size));

	vmemmap_remove_mapping(start, page_size);
	}
	}
	}
	#endif
	void register_page_bootmem_memmap(unsigned long section_nr,
	struct page *start_page, unsigned long size)
	{
	}

	/*
	* We do not have access to the sparsemem vmemmap, so we fallback to
	* walking the list of sparsemem blocks which we already maintain for
	* the sake of crashdump. In the long run, we might want to maintain
	* a tree if performance of that linear walk becomes a problem.
	*
	* realmode_pfn_to_page functions can fail due to:
	* 1) As real sparsemem blocks do not lay in RAM continously (they
	* are in virtual address space which is not available in the real mode),
	* the requested page struct can be split between blocks so get_page/put_page
	* may fail.
	* 2) When huge pages are used, the get_page/put_page API will fail
	* in real mode as the linked addresses in the page struct are virtual
	* too.
	*/
	struct page *realmode_pfn_to_page(unsigned long pfn)
	{
	struct vmemmap_backing *vmem_back;
	struct page *page;
	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
	unsigned long pg_va = (unsigned long) pfn_to_page(pfn);

	for (vmem_back = vmemmap_list; vmem_back; vmem_back = vmem_back->list) {
	if (pg_va < vmem_back->virt_addr)
	continue;

	/* After vmemmap_list entry free is possible, need check all */
	if ((pg_va + sizeof(struct page)) <=
	(vmem_back->virt_addr + page_size)) {
	page = (struct page *) (vmem_back->phys + pg_va -
	vmem_back->virt_addr);
	return page;
	}
	}

	/* Probably that page struct is split between real pages */
	return NULL;
	}
	EXPORT_SYMBOL_GPL(realmode_pfn_to_page);

	#elif defined(CONFIG_FLATMEM)

	struct page *realmode_pfn_to_page(unsigned long pfn)
	{
	struct page *page = pfn_to_page(pfn);
	return page;
	}
	EXPORT_SYMBOL_GPL(realmode_pfn_to_page);

	#endif /* CONFIG_SPARSEMEM_VMEMMAP/CONFIG_FLATMEM */