text: /*
   *  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/mm.h>
  #include <linux/kernel_stat.h>
  #include <linux/swap.h>
  #include <linux/interrupt.h>
  #include <linux/init.h>
  #include <linux/bootmem.h>
  #include <linux/mmzone.h>
  #include <linux/module.h>
  #include <asm/dma.h>
  #include <asm/io.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_SYMBOL(max_pfn);		/* This is exported so
  				 * dma_get_required_mask(), which uses
  				 * it, can be an inline function */
  
  #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;
  }
  
  /*
   * 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 = ((end - start)+7)/8;
  
  	pgdat->pgdat_next = pgdat_list;
  	pgdat_list = pgdat;
  
  	mapsize = ALIGN(mapsize, sizeof(long));
  	bdata->node_bootmem_map = phys_to_virt(mapstart << PAGE_SHIFT);
  	bdata->node_boot_start = (start << PAGE_SHIFT);
  	bdata->node_low_pfn = end;
  
  	/*
  	 * Initially all pages are reserved - setup_arch() has to
  	 * register free RAM areas explicitly.
  	 */
  	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 i;
  	/*
  	 * round up, partially reserved pages are considered
  	 * fully reserved.
  	 */
  	unsigned long sidx = (addr - bdata->node_boot_start)/PAGE_SIZE;
  	unsigned long eidx = (addr + size - bdata->node_boot_start + 
  							PAGE_SIZE-1)/PAGE_SIZE;
  	unsigned long end = (addr + size + PAGE_SIZE-1)/PAGE_SIZE;
  
  	BUG_ON(!size);
  	BUG_ON(sidx >= eidx);
  	BUG_ON((addr >> PAGE_SHIFT) >= bdata->node_low_pfn);
  	BUG_ON(end > bdata->node_low_pfn);
  
  	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.\n", i*PAGE_SIZE);
  #endif
  		}
  }
  
  static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)
  {
  	unsigned long i;
  	unsigned long start;
  	/*
  	 * round down end of usable mem, partially free pages are
  	 * considered reserved.
  	 */
  	unsigned long sidx;
  	unsigned long eidx = (addr + size - bdata->node_boot_start)/PAGE_SIZE;
  	unsigned long end = (addr + size)/PAGE_SIZE;
  
  	BUG_ON(!size);
  	BUG_ON(end > bdata->node_low_pfn);
  
  	if (addr < bdata->last_success)
  		bdata->last_success = addr;
  
  	/*
  	 * Round up the beginning of the address.
  	 */
  	start = (addr + PAGE_SIZE-1) / PAGE_SIZE;
  	sidx = start - (bdata->node_boot_start/PAGE_SIZE);
  
  	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.
   */
  static 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 = bdata->node_low_pfn;
  	void *ret;
  
  	if(!size) {
  		printk("__alloc_bootmem_core(): zero-sized request\n");
  		BUG();
  	}
  	BUG_ON(align & (align-1));
  
  	if (limit && bdata->node_boot_start >= limit)
  		return NULL;
  
          limit >>=PAGE_SHIFT;
  	if (limit && end_pfn > limit)
  		end_pfn = limit;
  
  	eidx = end_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
  	offset = 0;
  	if (align &&
  	    (bdata->node_boot_start & (align - 1UL)) != 0)
  		offset = (align - (bdata->node_boot_start & (align - 1UL)));
  	offset >>= PAGE_SHIFT;
  
  	/*
  	 * We try to allocate bootmem pages above 'goal'
  	 * first, then we try to allocate lower pages.
  	 */
  	if (goal && (goal >= bdata->node_boot_start) && 
  	    ((goal >> PAGE_SHIFT) < 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 = ALIGN(preferred, align) >> PAGE_SHIFT;
  	preferred += 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 = start << PAGE_SHIFT;
  	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 = bdata->node_boot_start >> PAGE_SHIFT;
  	idx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
  	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;
  	for (i = 0; i < ((bdata->node_low_pfn-(bdata->node_boot_start >> PAGE_SHIFT))/8 + PAGE_SIZE-1)/PAGE_SIZE; i++,page++) {
  		count++;
  		__free_pages_bootmem(page, 0);
  	}
  	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(unsigned long size, unsigned long align, unsigned long goal)
  {
  	pg_data_t *pgdat = pgdat_list;
  	void *ptr;
  
  	for_each_pgdat(pgdat)
  		if ((ptr = __alloc_bootmem_core(pgdat->bdata, size,
  						 align, goal, 0)))
  			return(ptr);
  
  	/*
  	 * Whoops, we cannot satisfy the allocation request.
  	 */
  	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", 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);
  }
  
  #define LOW32LIMIT 0xffffffff
  
  void * __init __alloc_bootmem_low(unsigned long size, unsigned long align, unsigned long goal)
  {
  	pg_data_t *pgdat = pgdat_list;
  	void *ptr;
  
  	for_each_pgdat(pgdat)
  		if ((ptr = __alloc_bootmem_core(pgdat->bdata, size,
  						 align, goal, LOW32LIMIT)))
  			return(ptr);
  
  	/*
  	 * Whoops, we cannot satisfy the allocation request.
  	 */
  	printk(KERN_ALERT "low bootmem alloc of %lu bytes failed!\n", 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, LOW32LIMIT);
  }
  