/*
   *  linux/mm/bootmem.c
   *
   *  Copyright (C) 1999 Ingo Molnar
   *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
   *
   *  simple boot-time physical memory area allocator and
   *  free memory collector. It's used to deal with reserved
   *  system memory and memory holes as well.
   */

  #include <linux/init.h>

  #include <linux/pfn.h>

  #include <linux/bootmem.h>

  #include <linux/module.h>

  
  #include <asm/bug.h>

  #include <asm/io.h>

  #include <asm/processor.h>

  #include "internal.h"
  
  /*
   * Access to this subsystem has to be serialized externally. (this is
   * true for the boot process anyway)
   */
  unsigned long max_low_pfn;
  unsigned long min_low_pfn;
  unsigned long max_pfn;

  EXPORT_UNUSED_SYMBOL(max_pfn);  /*  June 2006  */

  static LIST_HEAD(bdata_list);

  #ifdef CONFIG_CRASH_DUMP
  /*
   * If we have booted due to a crash, max_pfn will be a very low value. We need
   * to know the amount of memory that the previous kernel used.
   */
  unsigned long saved_max_pfn;
  #endif

  /* return the number of _pages_ that will be allocated for the boot bitmap */

  unsigned long __init bootmem_bootmap_pages(unsigned long pages)

  {
  	unsigned long mapsize;
  
  	mapsize = (pages+7)/8;
  	mapsize = (mapsize + ~PAGE_MASK) & PAGE_MASK;
  	mapsize >>= PAGE_SHIFT;
  
  	return mapsize;
  }

  /*
   * link bdata in order
   */

  static void __init link_bootmem(bootmem_data_t *bdata)

  {
  	bootmem_data_t *ent;

  	if (list_empty(&bdata_list)) {
  		list_add(&bdata->list, &bdata_list);
  		return;
  	}
  	/* insert in order */
  	list_for_each_entry(ent, &bdata_list, list) {
  		if (bdata->node_boot_start < ent->node_boot_start) {
  			list_add_tail(&bdata->list, &ent->list);
  			return;
  		}
  	}
  	list_add_tail(&bdata->list, &bdata_list);

  }

  /*
   * Given an initialised bdata, it returns the size of the boot bitmap
   */
  static unsigned long __init get_mapsize(bootmem_data_t *bdata)
  {
  	unsigned long mapsize;
  	unsigned long start = PFN_DOWN(bdata->node_boot_start);
  	unsigned long end = bdata->node_low_pfn;
  
  	mapsize = ((end - start) + 7) / 8;
  	return ALIGN(mapsize, sizeof(long));
  }

  
  /*
   * Called once to set up the allocator itself.
   */

  static unsigned long __init init_bootmem_core(pg_data_t *pgdat,

  	unsigned long mapstart, unsigned long start, unsigned long end)
  {
  	bootmem_data_t *bdata = pgdat->bdata;

  	unsigned long mapsize;

  	bdata->node_bootmem_map = phys_to_virt(PFN_PHYS(mapstart));
  	bdata->node_boot_start = PFN_PHYS(start);

  	bdata->node_low_pfn = end;

  	link_bootmem(bdata);

  
  	/*
  	 * Initially all pages are reserved - setup_arch() has to
  	 * register free RAM areas explicitly.
  	 */

  	mapsize = get_mapsize(bdata);

  	memset(bdata->node_bootmem_map, 0xff, mapsize);
  
  	return mapsize;
  }
  
  /*
   * Marks a particular physical memory range as unallocatable. Usable RAM
   * might be used for boot-time allocations - or it might get added
   * to the free page pool later on.
   */

  static void __init reserve_bootmem_core(bootmem_data_t *bdata, unsigned long addr,
  					unsigned long size)

  {

  	unsigned long sidx, eidx;

  	unsigned long i;

  	/*
  	 * round up, partially reserved pages are considered
  	 * fully reserved.
  	 */

  	BUG_ON(!size);

  	BUG_ON(PFN_DOWN(addr) >= bdata->node_low_pfn);
  	BUG_ON(PFN_UP(addr + size) > bdata->node_low_pfn);
  
  	sidx = PFN_DOWN(addr - bdata->node_boot_start);
  	eidx = PFN_UP(addr + size - bdata->node_boot_start);

  
  	for (i = sidx; i < eidx; i++)
  		if (test_and_set_bit(i, bdata->node_bootmem_map)) {
  #ifdef CONFIG_DEBUG_BOOTMEM
  			printk("hm, page %08lx reserved twice.
  ", i*PAGE_SIZE);
  #endif
  		}
  }

  static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr,
  				     unsigned long size)

  {

  	unsigned long sidx, eidx;

  	unsigned long i;

  	/*
  	 * round down end of usable mem, partially free pages are
  	 * considered reserved.
  	 */

  	BUG_ON(!size);

  	BUG_ON(PFN_DOWN(addr + size) > bdata->node_low_pfn);

  
  	if (addr < bdata->last_success)
  		bdata->last_success = addr;
  
  	/*
  	 * Round up the beginning of the address.
  	 */

  	sidx = PFN_UP(addr) - PFN_DOWN(bdata->node_boot_start);
  	eidx = PFN_DOWN(addr + size - bdata->node_boot_start);

  
  	for (i = sidx; i < eidx; i++) {
  		if (unlikely(!test_and_clear_bit(i, bdata->node_bootmem_map)))
  			BUG();
  	}
  }
  
  /*
   * We 'merge' subsequent allocations to save space. We might 'lose'
   * some fraction of a page if allocations cannot be satisfied due to
   * size constraints on boxes where there is physical RAM space
   * fragmentation - in these cases (mostly large memory boxes) this
   * is not a problem.
   *
   * On low memory boxes we get it right in 100% of the cases.
   *
   * alignment has to be a power of 2 value.
   *
   * NOTE:  This function is _not_ reentrant.
   */

  void * __init

  __alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,

  	      unsigned long align, unsigned long goal, unsigned long limit)

  {
  	unsigned long offset, remaining_size, areasize, preferred;

  	unsigned long i, start = 0, incr, eidx, end_pfn;

  	void *ret;

  	if (!size) {

  		printk("__alloc_bootmem_core(): zero-sized request
  ");
  		BUG();
  	}
  	BUG_ON(align & (align-1));

  	if (limit && bdata->node_boot_start >= limit)
  		return NULL;

  	end_pfn = bdata->node_low_pfn;
  	limit = PFN_DOWN(limit);

  	if (limit && end_pfn > limit)
  		end_pfn = limit;

  	eidx = end_pfn - PFN_DOWN(bdata->node_boot_start);

  	offset = 0;

  	if (align && (bdata->node_boot_start & (align - 1UL)) != 0)
  		offset = align - (bdata->node_boot_start & (align - 1UL));
  	offset = PFN_DOWN(offset);

  
  	/*
  	 * We try to allocate bootmem pages above 'goal'
  	 * first, then we try to allocate lower pages.
  	 */

  	if (goal && goal >= bdata->node_boot_start && PFN_DOWN(goal) < end_pfn) {

  		preferred = goal - bdata->node_boot_start;
  
  		if (bdata->last_success >= preferred)

  			if (!limit || (limit && limit > bdata->last_success))
  				preferred = bdata->last_success;

  	} else
  		preferred = 0;

  	preferred = PFN_DOWN(ALIGN(preferred, align)) + offset;
  	areasize = (size + PAGE_SIZE-1) / PAGE_SIZE;

  	incr = align >> PAGE_SHIFT ? : 1;
  
  restart_scan:
  	for (i = preferred; i < eidx; i += incr) {
  		unsigned long j;
  		i = find_next_zero_bit(bdata->node_bootmem_map, eidx, i);
  		i = ALIGN(i, incr);

  		if (i >= eidx)
  			break;

  		if (test_bit(i, bdata->node_bootmem_map))
  			continue;
  		for (j = i + 1; j < i + areasize; ++j) {
  			if (j >= eidx)
  				goto fail_block;

  			if (test_bit(j, bdata->node_bootmem_map))

  				goto fail_block;
  		}
  		start = i;
  		goto found;
  	fail_block:
  		i = ALIGN(j, incr);
  	}
  
  	if (preferred > offset) {
  		preferred = offset;
  		goto restart_scan;
  	}
  	return NULL;
  
  found:

  	bdata->last_success = PFN_PHYS(start);

  	BUG_ON(start >= eidx);
  
  	/*
  	 * Is the next page of the previous allocation-end the start
  	 * of this allocation's buffer? If yes then we can 'merge'
  	 * the previous partial page with this allocation.
  	 */
  	if (align < PAGE_SIZE &&
  	    bdata->last_offset && bdata->last_pos+1 == start) {

  		offset = ALIGN(bdata->last_offset, align);

  		BUG_ON(offset > PAGE_SIZE);

  		remaining_size = PAGE_SIZE - offset;

  		if (size < remaining_size) {
  			areasize = 0;
  			/* last_pos unchanged */

  			bdata->last_offset = offset + size;
  			ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
  					   offset +
  					   bdata->node_boot_start);

  		} else {
  			remaining_size = size - remaining_size;

  			areasize = (remaining_size + PAGE_SIZE-1) / PAGE_SIZE;
  			ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
  					   offset +
  					   bdata->node_boot_start);
  			bdata->last_pos = start + areasize - 1;

  			bdata->last_offset = remaining_size;
  		}
  		bdata->last_offset &= ~PAGE_MASK;
  	} else {
  		bdata->last_pos = start + areasize - 1;
  		bdata->last_offset = size & ~PAGE_MASK;
  		ret = phys_to_virt(start * PAGE_SIZE + bdata->node_boot_start);
  	}
  
  	/*
  	 * Reserve the area now:
  	 */

  	for (i = start; i < start + areasize; i++)

  		if (unlikely(test_and_set_bit(i, bdata->node_bootmem_map)))
  			BUG();
  	memset(ret, 0, size);
  	return ret;
  }
  
  static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
  {
  	struct page *page;

  	unsigned long pfn;

  	bootmem_data_t *bdata = pgdat->bdata;
  	unsigned long i, count, total = 0;
  	unsigned long idx;
  	unsigned long *map; 
  	int gofast = 0;
  
  	BUG_ON(!bdata->node_bootmem_map);
  
  	count = 0;
  	/* first extant page of the node */

  	pfn = PFN_DOWN(bdata->node_boot_start);
  	idx = bdata->node_low_pfn - pfn;

  	map = bdata->node_bootmem_map;
  	/* Check physaddr is O(LOG2(BITS_PER_LONG)) page aligned */
  	if (bdata->node_boot_start == 0 ||
  	    ffs(bdata->node_boot_start) - PAGE_SHIFT > ffs(BITS_PER_LONG))
  		gofast = 1;
  	for (i = 0; i < idx; ) {
  		unsigned long v = ~map[i / BITS_PER_LONG];

  		if (gofast && v == ~0UL) {

  			int order;

  			page = pfn_to_page(pfn);

  			count += BITS_PER_LONG;

  			order = ffs(BITS_PER_LONG) - 1;

  			__free_pages_bootmem(page, order);

  			i += BITS_PER_LONG;
  			page += BITS_PER_LONG;
  		} else if (v) {
  			unsigned long m;

  
  			page = pfn_to_page(pfn);

  			for (m = 1; m && i < idx; m<<=1, page++, i++) {
  				if (v & m) {
  					count++;

  					__free_pages_bootmem(page, 0);

  				}
  			}
  		} else {

  			i += BITS_PER_LONG;

  		}

  		pfn += BITS_PER_LONG;

  	}
  	total += count;
  
  	/*
  	 * Now free the allocator bitmap itself, it's not
  	 * needed anymore:
  	 */
  	page = virt_to_page(bdata->node_bootmem_map);
  	count = 0;

  	idx = (get_mapsize(bdata) + PAGE_SIZE-1) >> PAGE_SHIFT;
  	for (i = 0; i < idx; i++, page++) {

  		__free_pages_bootmem(page, 0);

  		count++;

  	}
  	total += count;
  	bdata->node_bootmem_map = NULL;
  
  	return total;
  }

  unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn,

  				unsigned long startpfn, unsigned long endpfn)

  {

  	return init_bootmem_core(pgdat, freepfn, startpfn, endpfn);

  }

  void __init reserve_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
  				 unsigned long size)

  {
  	reserve_bootmem_core(pgdat->bdata, physaddr, size);
  }

  void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
  			      unsigned long size)

  {
  	free_bootmem_core(pgdat->bdata, physaddr, size);
  }

  unsigned long __init free_all_bootmem_node(pg_data_t *pgdat)

  {

  	return free_all_bootmem_core(pgdat);

  }

  unsigned long __init init_bootmem(unsigned long start, unsigned long pages)

  {
  	max_low_pfn = pages;
  	min_low_pfn = start;

  	return init_bootmem_core(NODE_DATA(0), start, 0, pages);

  }
  
  #ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE

  void __init reserve_bootmem(unsigned long addr, unsigned long size)

  {
  	reserve_bootmem_core(NODE_DATA(0)->bdata, addr, size);
  }
  #endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */

  void __init free_bootmem(unsigned long addr, unsigned long size)

  {
  	free_bootmem_core(NODE_DATA(0)->bdata, addr, size);
  }

  unsigned long __init free_all_bootmem(void)

  {

  	return free_all_bootmem_core(NODE_DATA(0));

  }

  void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
  				      unsigned long goal)

  {

  	bootmem_data_t *bdata;

  	void *ptr;

  	list_for_each_entry(bdata, &bdata_list, list) {
  		ptr = __alloc_bootmem_core(bdata, size, align, goal, 0);
  		if (ptr)
  			return ptr;
  	}

  	return NULL;
  }

  void * __init __alloc_bootmem(unsigned long size, unsigned long align,
  			      unsigned long goal)

  {
  	void *mem = __alloc_bootmem_nopanic(size,align,goal);

  	if (mem)
  		return mem;

  	/*
  	 * Whoops, we cannot satisfy the allocation request.
  	 */
  	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!
  ", size);
  	panic("Out of memory");
  	return NULL;
  }

  void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
  				   unsigned long align, unsigned long goal)

  {
  	void *ptr;

  	ptr = __alloc_bootmem_core(pgdat->bdata, size, align, goal, 0);

  	if (ptr)

  		return ptr;

  	return __alloc_bootmem(size, align, goal);

  }

  #ifndef ARCH_LOW_ADDRESS_LIMIT
  #define ARCH_LOW_ADDRESS_LIMIT	0xffffffffUL
  #endif

  void * __init __alloc_bootmem_low(unsigned long size, unsigned long align,
  				  unsigned long goal)

  {

  	bootmem_data_t *bdata;

  	void *ptr;

  	list_for_each_entry(bdata, &bdata_list, list) {

  		ptr = __alloc_bootmem_core(bdata, size, align, goal,
  						ARCH_LOW_ADDRESS_LIMIT);

  		if (ptr)
  			return ptr;
  	}

  
  	/*
  	 * Whoops, we cannot satisfy the allocation request.
  	 */
  	printk(KERN_ALERT "low bootmem alloc of %lu bytes failed!
  ", size);
  	panic("Out of low memory");
  	return NULL;
  }
  
  void * __init __alloc_bootmem_low_node(pg_data_t *pgdat, unsigned long size,
  				       unsigned long align, unsigned long goal)
  {

  	return __alloc_bootmem_core(pgdat->bdata, size, align, goal,
  				    ARCH_LOW_ADDRESS_LIMIT);

  }