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

 /*
  *    Copyright IBM Corp. 2006
  *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
  */

 #include <linux/bootmem.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/memblock.h>
 #include <asm/cacheflush.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
 #include <asm/setup.h>
 #include <asm/tlbflush.h>
 #include <asm/sections.h>
 #include <asm/set_memory.h>

 static DEFINE_MUTEX(vmem_mutex);

 struct memory_segment {
 	struct list_head list;
 	unsigned long start;
 	unsigned long size;
 };

 static LIST_HEAD(mem_segs);

 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 (void *) memblock_alloc(size, size);
 }

 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;
 	clear_table((unsigned long *) pte, _PAGE_INVALID, size);
 	return pte;
 }

 /*
  * Add a physical memory range to the 1:1 mapping.
  */
 static int vmem_add_mem(unsigned long start, unsigned long size)
 {
 	unsigned long pgt_prot, sgt_prot, r3_prot;
 	unsigned long pages4k, pages1m, pages2g;
 	unsigned long end = start + size;
 	unsigned long address = start;
 	pgd_t *pg_dir;
 	p4d_t *p4_dir;
 	pud_t *pu_dir;
 	pmd_t *pm_dir;
 	pte_t *pt_dir;
 	int ret = -ENOMEM;

 	pgt_prot = pgprot_val(PAGE_KERNEL);
 	sgt_prot = pgprot_val(SEGMENT_KERNEL);
 	r3_prot = pgprot_val(REGION3_KERNEL);
 	if (!MACHINE_HAS_NX) {
 		pgt_prot &= ~_PAGE_NOEXEC;
 		sgt_prot &= ~_SEGMENT_ENTRY_NOEXEC;
 		r3_prot &= ~_REGION_ENTRY_NOEXEC;
 	}
 	pages4k = pages1m = pages2g = 0;
 	while (address < end) {
 		pg_dir = pgd_offset_k(address);
 		if (pgd_none(*pg_dir)) {
 			p4_dir = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
 			if (!p4_dir)
 				goto out;
 			pgd_populate(&init_mm, pg_dir, p4_dir);
 		}
 		p4_dir = p4d_offset(pg_dir, address);
 		if (p4d_none(*p4_dir)) {
 			pu_dir = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
 			if (!pu_dir)
 				goto out;
 			p4d_populate(&init_mm, p4_dir, pu_dir);
 		}
 		pu_dir = pud_offset(p4_dir, address);
 		if (MACHINE_HAS_EDAT2 && pud_none(*pu_dir) && address &&
 		    !(address & ~PUD_MASK) && (address + PUD_SIZE <= end) &&
 		     !debug_pagealloc_enabled()) {
 			pud_val(*pu_dir) = address | r3_prot;
 			address += PUD_SIZE;
 			pages2g++;
 			continue;
 		}
 		if (pud_none(*pu_dir)) {
 			pm_dir = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 			if (!pm_dir)
 				goto out;
 			pud_populate(&init_mm, pu_dir, pm_dir);
 		}
 		pm_dir = pmd_offset(pu_dir, address);
 		if (MACHINE_HAS_EDAT1 && pmd_none(*pm_dir) && address &&
 		    !(address & ~PMD_MASK) && (address + PMD_SIZE <= end) &&
 		    !debug_pagealloc_enabled()) {
 			pmd_val(*pm_dir) = address | sgt_prot;
 			address += PMD_SIZE;
 			pages1m++;
 			continue;
 		}
 		if (pmd_none(*pm_dir)) {
 			pt_dir = vmem_pte_alloc();
 			if (!pt_dir)
 				goto out;
 			pmd_populate(&init_mm, pm_dir, pt_dir);
 		}

 		pt_dir = pte_offset_kernel(pm_dir, address);
 		pte_val(*pt_dir) = address | pgt_prot;
 		address += PAGE_SIZE;
 		pages4k++;
 	}
 	ret = 0;
 out:
 	update_page_count(PG_DIRECT_MAP_4K, pages4k);
 	update_page_count(PG_DIRECT_MAP_1M, pages1m);
 	update_page_count(PG_DIRECT_MAP_2G, pages2g);
 	return ret;
 }

 /*
  * Remove a physical memory range from the 1:1 mapping.
  * Currently only invalidates page table entries.
  */
 static void vmem_remove_range(unsigned long start, unsigned long size)
 {
 	unsigned long pages4k, pages1m, pages2g;
 	unsigned long end = start + size;
 	unsigned long address = start;
 	pgd_t *pg_dir;
 	p4d_t *p4_dir;
 	pud_t *pu_dir;
 	pmd_t *pm_dir;
 	pte_t *pt_dir;

 	pages4k = pages1m = pages2g = 0;
 	while (address < end) {
 		pg_dir = pgd_offset_k(address);
 		if (pgd_none(*pg_dir)) {
 			address += PGDIR_SIZE;
 			continue;
 		}
 		p4_dir = p4d_offset(pg_dir, address);
 		if (p4d_none(*p4_dir)) {
 			address += P4D_SIZE;
 			continue;
 		}
 		pu_dir = pud_offset(p4_dir, address);
 		if (pud_none(*pu_dir)) {
 			address += PUD_SIZE;
 			continue;
 		}
 		if (pud_large(*pu_dir)) {
 			pud_clear(pu_dir);
 			address += PUD_SIZE;
 			pages2g++;
 			continue;
 		}
 		pm_dir = pmd_offset(pu_dir, address);
 		if (pmd_none(*pm_dir)) {
 			address += PMD_SIZE;
 			continue;
 		}
 		if (pmd_large(*pm_dir)) {
 			pmd_clear(pm_dir);
 			address += PMD_SIZE;
 			pages1m++;
 			continue;
 		}
 		pt_dir = pte_offset_kernel(pm_dir, address);
 		pte_clear(&init_mm, address, pt_dir);
 		address += PAGE_SIZE;
 		pages4k++;
 	}
 	flush_tlb_kernel_range(start, end);
 	update_page_count(PG_DIRECT_MAP_4K, -pages4k);
 	update_page_count(PG_DIRECT_MAP_1M, -pages1m);
 	update_page_count(PG_DIRECT_MAP_2G, -pages2g);
 }

 /*
  * Add a backed mem_map array to the virtual mem_map array.
  */
 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
 {
 	unsigned long pgt_prot, sgt_prot;
 	unsigned long address = start;
 	pgd_t *pg_dir;
 	p4d_t *p4_dir;
 	pud_t *pu_dir;
 	pmd_t *pm_dir;
 	pte_t *pt_dir;
 	int ret = -ENOMEM;

 	pgt_prot = pgprot_val(PAGE_KERNEL);
 	sgt_prot = pgprot_val(SEGMENT_KERNEL);
 	if (!MACHINE_HAS_NX) {
 		pgt_prot &= ~_PAGE_NOEXEC;
 		sgt_prot &= ~_SEGMENT_ENTRY_NOEXEC;
 	}
 	for (address = start; address < end;) {
 		pg_dir = pgd_offset_k(address);
 		if (pgd_none(*pg_dir)) {
 			p4_dir = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
 			if (!p4_dir)
 				goto out;
 			pgd_populate(&init_mm, pg_dir, p4_dir);
 		}

 		p4_dir = p4d_offset(pg_dir, address);
 		if (p4d_none(*p4_dir)) {
 			pu_dir = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
 			if (!pu_dir)
 				goto out;
 			p4d_populate(&init_mm, p4_dir, pu_dir);
 		}

 		pu_dir = pud_offset(p4_dir, address);
 		if (pud_none(*pu_dir)) {
 			pm_dir = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 			if (!pm_dir)
 				goto out;
 			pud_populate(&init_mm, pu_dir, pm_dir);
 		}

 		pm_dir = pmd_offset(pu_dir, address);
 		if (pmd_none(*pm_dir)) {
 			/* 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. */
 			if (MACHINE_HAS_EDAT1) {
 				void *new_page;

 				new_page = vmemmap_alloc_block(PMD_SIZE, node);
 				if (!new_page)
 					goto out;
 				pmd_val(*pm_dir) = __pa(new_page) | sgt_prot;
 				address = (address + PMD_SIZE) & PMD_MASK;
 				continue;
 			}
 			pt_dir = vmem_pte_alloc();
 			if (!pt_dir)
 				goto out;
 			pmd_populate(&init_mm, pm_dir, pt_dir);
 		} else if (pmd_large(*pm_dir)) {
 			address = (address + PMD_SIZE) & PMD_MASK;
 			continue;
 		}

 		pt_dir = pte_offset_kernel(pm_dir, address);
 		if (pte_none(*pt_dir)) {
 			void *new_page;

 			new_page = vmemmap_alloc_block(PAGE_SIZE, node);
 			if (!new_page)
 				goto out;
 			pte_val(*pt_dir) = __pa(new_page) | pgt_prot;
 		}
 		address += PAGE_SIZE;
 	}
 	ret = 0;
 out:
 	return ret;
 }

 void vmemmap_free(unsigned long start, unsigned long end)
 {
 }

 /*
  * Add memory segment to the segment list if it doesn't overlap with
  * an already present segment.
  */
 static int insert_memory_segment(struct memory_segment *seg)
 {
 	struct memory_segment *tmp;

 	if (seg->start + seg->size > VMEM_MAX_PHYS ||
 	    seg->start + seg->size < seg->start)
 		return -ERANGE;

 	list_for_each_entry(tmp, &mem_segs, list) {
 		if (seg->start >= tmp->start + tmp->size)
 			continue;
 		if (seg->start + seg->size <= tmp->start)
 			continue;
 		return -ENOSPC;
 	}
 	list_add(&seg->list, &mem_segs);
 	return 0;
 }

 /*
  * Remove memory segment from the segment list.
  */
 static void remove_memory_segment(struct memory_segment *seg)
 {
 	list_del(&seg->list);
 }

 static void __remove_shared_memory(struct memory_segment *seg)
 {
 	remove_memory_segment(seg);
 	vmem_remove_range(seg->start, seg->size);
 }

 int vmem_remove_mapping(unsigned long start, unsigned long size)
 {
 	struct memory_segment *seg;
 	int ret;

 	mutex_lock(&vmem_mutex);

 	ret = -ENOENT;
 	list_for_each_entry(seg, &mem_segs, list) {
 		if (seg->start == start && seg->size == size)
 			break;
 	}

 	if (seg->start != start || seg->size != size)
 		goto out;

 	ret = 0;
 	__remove_shared_memory(seg);
 	kfree(seg);
 out:
 	mutex_unlock(&vmem_mutex);
 	return ret;
 }

 int vmem_add_mapping(unsigned long start, unsigned long size)
 {
 	struct memory_segment *seg;
 	int ret;

 	mutex_lock(&vmem_mutex);
 	ret = -ENOMEM;
 	seg = kzalloc(sizeof(*seg), GFP_KERNEL);
 	if (!seg)
 		goto out;
 	seg->start = start;
 	seg->size = size;

 	ret = insert_memory_segment(seg);
 	if (ret)
 		goto out_free;

 	ret = vmem_add_mem(start, size);
 	if (ret)
 		goto out_remove;
 	goto out;

 out_remove:
 	__remove_shared_memory(seg);
 out_free:
 	kfree(seg);
 out:
 	mutex_unlock(&vmem_mutex);
 	return ret;
 }

 /*
  * map whole physical memory to virtual memory (identity mapping)
  * we reserve enough space in the vmalloc area for vmemmap to hotplug
  * additional memory segments.
  */
 void __init vmem_map_init(void)
 {
 	struct memblock_region *reg;

 	for_each_memblock(memory, reg)
 		vmem_add_mem(reg->base, reg->size);
 	__set_memory((unsigned long) _stext,
 		     (_etext - _stext) >> PAGE_SHIFT,
 		     SET_MEMORY_RO | SET_MEMORY_X);
 	__set_memory((unsigned long) _etext,
 		     (_eshared - _etext) >> PAGE_SHIFT,
 		     SET_MEMORY_RO);
 	__set_memory((unsigned long) _sinittext,
 		     (_einittext - _sinittext) >> PAGE_SHIFT,
 		     SET_MEMORY_RO | SET_MEMORY_X);
 	pr_info("Write protected kernel read-only data: %luk\n",
 		(_eshared - _stext) >> 10);
 }

 /*
  * Convert memblock.memory  to a memory segment list so there is a single
  * list that contains all memory segments.
  */
 static int __init vmem_convert_memory_chunk(void)
 {
 	struct memblock_region *reg;
 	struct memory_segment *seg;

 	mutex_lock(&vmem_mutex);
 	for_each_memblock(memory, reg) {
 		seg = kzalloc(sizeof(*seg), GFP_KERNEL);
 		if (!seg)
 			panic("Out of memory...\n");
 		seg->start = reg->base;
 		seg->size = reg->size;
 		insert_memory_segment(seg);
 	}
 	mutex_unlock(&vmem_mutex);
 	return 0;
 }

 core_initcall(vmem_convert_memory_chunk);
	/*
	* Copyright IBM Corp. 2006
	* Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
	*/

	#include <linux/bootmem.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/memblock.h>
	#include <asm/cacheflush.h>
	#include <asm/pgalloc.h>
	#include <asm/pgtable.h>
	#include <asm/setup.h>
	#include <asm/tlbflush.h>
	#include <asm/sections.h>
	#include <asm/set_memory.h>

	static DEFINE_MUTEX(vmem_mutex);

	struct memory_segment {
	struct list_head list;
	unsigned long start;
	unsigned long size;
	};

	static LIST_HEAD(mem_segs);

	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 (void *) memblock_alloc(size, size);
	}

	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;
	clear_table((unsigned long *) pte, _PAGE_INVALID, size);
	return pte;
	}

	/*
	* Add a physical memory range to the 1:1 mapping.
	*/
	static int vmem_add_mem(unsigned long start, unsigned long size)
	{
	unsigned long pgt_prot, sgt_prot, r3_prot;
	unsigned long pages4k, pages1m, pages2g;
	unsigned long end = start + size;
	unsigned long address = start;
	pgd_t *pg_dir;
	p4d_t *p4_dir;
	pud_t *pu_dir;
	pmd_t *pm_dir;
	pte_t *pt_dir;
	int ret = -ENOMEM;

	pgt_prot = pgprot_val(PAGE_KERNEL);
	sgt_prot = pgprot_val(SEGMENT_KERNEL);
	r3_prot = pgprot_val(REGION3_KERNEL);
	if (!MACHINE_HAS_NX) {
	pgt_prot &= ~_PAGE_NOEXEC;
	sgt_prot &= ~_SEGMENT_ENTRY_NOEXEC;
	r3_prot &= ~_REGION_ENTRY_NOEXEC;
	}
	pages4k = pages1m = pages2g = 0;
	while (address < end) {
	pg_dir = pgd_offset_k(address);
	if (pgd_none(*pg_dir)) {
	p4_dir = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
	if (!p4_dir)
	goto out;
	pgd_populate(&init_mm, pg_dir, p4_dir);
	}
	p4_dir = p4d_offset(pg_dir, address);
	if (p4d_none(*p4_dir)) {
	pu_dir = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
	if (!pu_dir)
	goto out;
	p4d_populate(&init_mm, p4_dir, pu_dir);
	}
	pu_dir = pud_offset(p4_dir, address);
	if (MACHINE_HAS_EDAT2 && pud_none(*pu_dir) && address &&
	!(address & ~PUD_MASK) && (address + PUD_SIZE <= end) &&
	!debug_pagealloc_enabled()) {
	pud_val(*pu_dir) = address \| r3_prot;
	address += PUD_SIZE;
	pages2g++;
	continue;
	}
	if (pud_none(*pu_dir)) {
	pm_dir = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
	if (!pm_dir)
	goto out;
	pud_populate(&init_mm, pu_dir, pm_dir);
	}
	pm_dir = pmd_offset(pu_dir, address);
	if (MACHINE_HAS_EDAT1 && pmd_none(*pm_dir) && address &&
	!(address & ~PMD_MASK) && (address + PMD_SIZE <= end) &&
	!debug_pagealloc_enabled()) {
	pmd_val(*pm_dir) = address \| sgt_prot;
	address += PMD_SIZE;
	pages1m++;
	continue;
	}
	if (pmd_none(*pm_dir)) {
	pt_dir = vmem_pte_alloc();
	if (!pt_dir)
	goto out;
	pmd_populate(&init_mm, pm_dir, pt_dir);
	}

	pt_dir = pte_offset_kernel(pm_dir, address);
	pte_val(*pt_dir) = address \| pgt_prot;
	address += PAGE_SIZE;
	pages4k++;
	}
	ret = 0;
	out:
	update_page_count(PG_DIRECT_MAP_4K, pages4k);
	update_page_count(PG_DIRECT_MAP_1M, pages1m);
	update_page_count(PG_DIRECT_MAP_2G, pages2g);
	return ret;
	}

	/*
	* Remove a physical memory range from the 1:1 mapping.
	* Currently only invalidates page table entries.
	*/
	static void vmem_remove_range(unsigned long start, unsigned long size)
	{
	unsigned long pages4k, pages1m, pages2g;
	unsigned long end = start + size;
	unsigned long address = start;
	pgd_t *pg_dir;
	p4d_t *p4_dir;
	pud_t *pu_dir;
	pmd_t *pm_dir;
	pte_t *pt_dir;

	pages4k = pages1m = pages2g = 0;
	while (address < end) {
	pg_dir = pgd_offset_k(address);
	if (pgd_none(*pg_dir)) {
	address += PGDIR_SIZE;
	continue;
	}
	p4_dir = p4d_offset(pg_dir, address);
	if (p4d_none(*p4_dir)) {
	address += P4D_SIZE;
	continue;
	}
	pu_dir = pud_offset(p4_dir, address);
	if (pud_none(*pu_dir)) {
	address += PUD_SIZE;
	continue;
	}
	if (pud_large(*pu_dir)) {
	pud_clear(pu_dir);
	address += PUD_SIZE;
	pages2g++;
	continue;
	}
	pm_dir = pmd_offset(pu_dir, address);
	if (pmd_none(*pm_dir)) {
	address += PMD_SIZE;
	continue;
	}
	if (pmd_large(*pm_dir)) {
	pmd_clear(pm_dir);
	address += PMD_SIZE;
	pages1m++;
	continue;
	}
	pt_dir = pte_offset_kernel(pm_dir, address);
	pte_clear(&init_mm, address, pt_dir);
	address += PAGE_SIZE;
	pages4k++;
	}
	flush_tlb_kernel_range(start, end);
	update_page_count(PG_DIRECT_MAP_4K, -pages4k);
	update_page_count(PG_DIRECT_MAP_1M, -pages1m);
	update_page_count(PG_DIRECT_MAP_2G, -pages2g);
	}

	/*
	* Add a backed mem_map array to the virtual mem_map array.
	*/
	int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
	{
	unsigned long pgt_prot, sgt_prot;
	unsigned long address = start;
	pgd_t *pg_dir;
	p4d_t *p4_dir;
	pud_t *pu_dir;
	pmd_t *pm_dir;
	pte_t *pt_dir;
	int ret = -ENOMEM;

	pgt_prot = pgprot_val(PAGE_KERNEL);
	sgt_prot = pgprot_val(SEGMENT_KERNEL);
	if (!MACHINE_HAS_NX) {
	pgt_prot &= ~_PAGE_NOEXEC;
	sgt_prot &= ~_SEGMENT_ENTRY_NOEXEC;
	}
	for (address = start; address < end;) {
	pg_dir = pgd_offset_k(address);
	if (pgd_none(*pg_dir)) {
	p4_dir = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
	if (!p4_dir)
	goto out;
	pgd_populate(&init_mm, pg_dir, p4_dir);
	}

	p4_dir = p4d_offset(pg_dir, address);
	if (p4d_none(*p4_dir)) {
	pu_dir = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
	if (!pu_dir)
	goto out;
	p4d_populate(&init_mm, p4_dir, pu_dir);
	}

	pu_dir = pud_offset(p4_dir, address);
	if (pud_none(*pu_dir)) {
	pm_dir = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
	if (!pm_dir)
	goto out;
	pud_populate(&init_mm, pu_dir, pm_dir);
	}

	pm_dir = pmd_offset(pu_dir, address);
	if (pmd_none(*pm_dir)) {
	/* 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. */
	if (MACHINE_HAS_EDAT1) {
	void *new_page;

	new_page = vmemmap_alloc_block(PMD_SIZE, node);
	if (!new_page)
	goto out;
	pmd_val(*pm_dir) = __pa(new_page) \| sgt_prot;
	address = (address + PMD_SIZE) & PMD_MASK;
	continue;
	}
	pt_dir = vmem_pte_alloc();
	if (!pt_dir)
	goto out;
	pmd_populate(&init_mm, pm_dir, pt_dir);
	} else if (pmd_large(*pm_dir)) {
	address = (address + PMD_SIZE) & PMD_MASK;
	continue;
	}

	pt_dir = pte_offset_kernel(pm_dir, address);
	if (pte_none(*pt_dir)) {
	void *new_page;

	new_page = vmemmap_alloc_block(PAGE_SIZE, node);
	if (!new_page)
	goto out;
	pte_val(*pt_dir) = __pa(new_page) \| pgt_prot;
	}
	address += PAGE_SIZE;
	}
	ret = 0;
	out:
	return ret;
	}

	void vmemmap_free(unsigned long start, unsigned long end)
	{
	}

	/*
	* Add memory segment to the segment list if it doesn't overlap with
	* an already present segment.
	*/
	static int insert_memory_segment(struct memory_segment *seg)
	{
	struct memory_segment *tmp;

	if (seg->start + seg->size > VMEM_MAX_PHYS \|\|
	seg->start + seg->size < seg->start)
	return -ERANGE;

	list_for_each_entry(tmp, &mem_segs, list) {
	if (seg->start >= tmp->start + tmp->size)
	continue;
	if (seg->start + seg->size <= tmp->start)
	continue;
	return -ENOSPC;
	}
	list_add(&seg->list, &mem_segs);
	return 0;
	}

	/*
	* Remove memory segment from the segment list.
	*/
	static void remove_memory_segment(struct memory_segment *seg)
	{
	list_del(&seg->list);
	}

	static void __remove_shared_memory(struct memory_segment *seg)
	{
	remove_memory_segment(seg);
	vmem_remove_range(seg->start, seg->size);
	}

	int vmem_remove_mapping(unsigned long start, unsigned long size)
	{
	struct memory_segment *seg;
	int ret;

	mutex_lock(&vmem_mutex);

	ret = -ENOENT;
	list_for_each_entry(seg, &mem_segs, list) {
	if (seg->start == start && seg->size == size)
	break;
	}

	if (seg->start != start \|\| seg->size != size)
	goto out;

	ret = 0;
	__remove_shared_memory(seg);
	kfree(seg);
	out:
	mutex_unlock(&vmem_mutex);
	return ret;
	}

	int vmem_add_mapping(unsigned long start, unsigned long size)
	{
	struct memory_segment *seg;
	int ret;

	mutex_lock(&vmem_mutex);
	ret = -ENOMEM;
	seg = kzalloc(sizeof(*seg), GFP_KERNEL);
	if (!seg)
	goto out;
	seg->start = start;
	seg->size = size;

	ret = insert_memory_segment(seg);
	if (ret)
	goto out_free;

	ret = vmem_add_mem(start, size);
	if (ret)
	goto out_remove;
	goto out;

	out_remove:
	__remove_shared_memory(seg);
	out_free:
	kfree(seg);
	out:
	mutex_unlock(&vmem_mutex);
	return ret;
	}

	/*
	* map whole physical memory to virtual memory (identity mapping)
	* we reserve enough space in the vmalloc area for vmemmap to hotplug
	* additional memory segments.
	*/
	void __init vmem_map_init(void)
	{
	struct memblock_region *reg;

	for_each_memblock(memory, reg)
	vmem_add_mem(reg->base, reg->size);
	__set_memory((unsigned long) _stext,
	(_etext - _stext) >> PAGE_SHIFT,
	SET_MEMORY_RO \| SET_MEMORY_X);
	__set_memory((unsigned long) _etext,
	(_eshared - _etext) >> PAGE_SHIFT,
	SET_MEMORY_RO);
	__set_memory((unsigned long) _sinittext,
	(_einittext - _sinittext) >> PAGE_SHIFT,
	SET_MEMORY_RO \| SET_MEMORY_X);
	pr_info("Write protected kernel read-only data: %luk\n",
	(_eshared - _stext) >> 10);
	}

	/*
	* Convert memblock.memory to a memory segment list so there is a single
	* list that contains all memory segments.
	*/
	static int __init vmem_convert_memory_chunk(void)
	{
	struct memblock_region *reg;
	struct memory_segment *seg;

	mutex_lock(&vmem_mutex);
	for_each_memblock(memory, reg) {
	seg = kzalloc(sizeof(*seg), GFP_KERNEL);
	if (!seg)
	panic("Out of memory...\n");
	seg->start = reg->base;
	seg->size = reg->size;
	insert_memory_segment(seg);
	}
	mutex_unlock(&vmem_mutex);
	return 0;
	}

	core_initcall(vmem_convert_memory_chunk);