/*
 * maps a range of physical memory into the requested pages. the old
 * mappings are removed. any references to nonexistent pages results
 * in null mappings (currently treated as "copy-on-access")
 */
static inline void remap_pte_range(pte_t * pte, unsigned long address, unsigned long size,
	unsigned long offset, pgprot_t prot)
{
	unsigned long end;

	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
		end = PMD_SIZE;
	do {
		pte_t oldpage = *pte;
		pte_clear(pte);
		if (offset >= high_memory || PageReserved(mem_map+MAP_NR(offset)))
 			set_pte(pte, mk_pte(offset, prot));
		forget_pte(oldpage);
		address += PAGE_SIZE;
		offset += PAGE_SIZE;
		pte++;
	} while (address < end);
}

/*
 * transfer all the memory from the bootmem allocator to the runtime allocator
 */
void __init mem_init(void)
{
	int codesize, reservedpages, datasize, initsize;
	int tmp;

	if (!mem_map)
		BUG();

#define START_PFN	(contig_page_data.bdata->node_min_pfn)
#define MAX_LOW_PFN	(contig_page_data.bdata->node_low_pfn)

	max_mapnr = num_physpages = MAX_LOW_PFN - START_PFN;
	high_memory = (void *) __va(MAX_LOW_PFN * PAGE_SIZE);

	/* clear the zero-page */
	memset(empty_zero_page, 0, PAGE_SIZE);

	/* this will put all low memory onto the freelists */
	totalram_pages += free_all_bootmem();

	reservedpages = 0;
	for (tmp = 0; tmp < num_physpages; tmp++)
		if (PageReserved(&mem_map[tmp]))
			reservedpages++;

	codesize =  (unsigned long) &_etext - (unsigned long) &_stext;
	datasize =  (unsigned long) &_edata - (unsigned long) &_etext;
	initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;

	printk(KERN_INFO
	       "Memory: %luk/%luk available"
	       " (%dk kernel code, %dk reserved, %dk data, %dk init,"
	       " %ldk highmem)\n",
	       nr_free_pages() << (PAGE_SHIFT - 10),
	       max_mapnr << (PAGE_SHIFT - 10),
	       codesize >> 10,
	       reservedpages << (PAGE_SHIFT - 10),
	       datasize >> 10,
	       initsize >> 10,
	       totalhigh_pages << (PAGE_SHIFT - 10));
}

static int _phymem_pages_proc_show(struct seq_file *m, void *v)
{
	int free = 0, total = 0, reserved = 0;
	int other = 0, shared = 0, cached = 0, slab = 0, node, i;

	struct meminfo * mi = &meminfo;
	for_each_bank (i,mi) {
		struct membank *bank = &mi->bank[i];
		unsigned int pfn1, pfn2;
		struct page *page, *end;
		pfn1 = bank_pfn_start(bank);
		pfn2 = bank_pfn_end(bank);
		page = pfn_to_page(pfn1);
		end  = pfn_to_page(pfn2 - 1) + 1;
		do {
			total++;
			if (PageReserved(page))
				reserved++;
			else if (PageSwapCache(page))
				cached++;
			else if (PageSlab(page))
				slab++;
			else if (page_count(page) > 1)
				shared++;
			else if (!page_count(page))
				free++;
			else
				other++;
			page++;
		}while (page < end);
	}

	seq_printf(m, "pages of RAM       %d\n", total);
	seq_printf(m, "free pages         %d\n", free);
	seq_printf(m, "reserved pages     %d\n", reserved);
	seq_printf(m, "slab pages         %d\n", slab);
	seq_printf(m, "pages shared       %d\n", shared);
	seq_printf(m, "pages swap cached  %d\n", cached);
	seq_printf(m, "other pages        %d\n", other);
	return 0;
}

void si_meminfo(struct sysinfo *val)
{
	int i;

	i = MAP_NR(high_memory);
	val->totalram = 0;
	val->sharedram = 0;
	val->freeram = nr_free_pages << PAGE_SHIFT;
	val->bufferram = buffermem;
	while (i-- > 0)  {
		if (PageReserved(mem_map+i))
			continue;
		val->totalram++;
		if (!atomic_read(&mem_map[i].count))
			continue;
		val->sharedram += atomic_read(&mem_map[i].count) - 1;
	}
	val->totalram <<= PAGE_SHIFT;
	val->sharedram <<= PAGE_SHIFT;
	return;
}

static void
default_init_memmap(struct Page *base, size_t n) {
    assert(n > 0);
	// n是页数
    struct Page *p = base;
    for (; p != base + n; p ++) {
        assert(PageReserved(p));
        p->flags = p->property = 0;
		SetPageProperty(p);
        set_page_ref(p, 0); // 引用计数设置为0
		// 也就是在free_list的前面插入，不过考虑到这是一个双向链表，所以实际的意思是，插到链表的尾部
		list_add_before(&free_list, &(p->page_link));
    }
	// 因为base是头表
	// property这个玩意只有在free block首地址对应的Page有用，其余都被设置为了0
	// 用于指示这个free block一共有多少个free page
    base->property = n; // 可用的页面数是n
    SetPageProperty(base); // base所在的页面为头表
    nr_free += n; // 空闲的页面数目增加了n
    //list_add(&free_list, &(base->page_link)); // 添加到free_list的头部
}

void si_meminfo(struct sysinfo *val)
{
    unsigned long i;

    i = (high_memory - PAGE_OFFSET) >> PAGE_SHIFT;
    val->totalram = 0;
    val->sharedram = 0;
    val->freeram = nr_free_pages << PAGE_SHIFT;
    val->bufferram = buffermem;
    while (i-- > 0) {
	if (PageReserved(mem_map+i))
	    continue;
	val->totalram++;
	if (!mem_map[i].count)
	    continue;
	val->sharedram += mem_map[i].count-1;
    }
    val->totalram <<= PAGE_SHIFT;
    val->sharedram <<= PAGE_SHIFT;
    return;
}

static void default_free_pages(struct Page *base, size_t n) {
	assert(n > 0);
	struct Page *p = base;
	for (; p != base + n; p ++) { 
		assert(!PageReserved(p) && !PageProperty(p));
        p->flags = 0;
        set_page_ref(p, 0);
    }
    base->property = n;
    SetPageProperty(base);
    list_entry_t *le = list_next(&free_list);
    while (le != &free_list) {
        p = le2page(le, page_link);
        le = list_next(le);
        if (base + base->property == p) {
            base->property += p->property;
            ClearPageProperty(p);
            list_del(&(p->page_link));
        }
        else if (p + p->property == base) {
            p->property += base->property;
            ClearPageProperty(base);
            base = p;
            list_del(&(p->page_link));
        }
    }
    nr_free += n;
    //list_add(&free_list, &(base->page_link));
	list_entry_t *curr=&free_list;
	while((curr=list_next(curr))!=&free_list){
		struct Page *currp=le2page(curr,page_link);
		if(p<currp){
			list_add_before(curr,&(base->page_link));
			break;
		}
	}
	if(curr==&free_list){
		list_add_before(curr,&(base->page_link));
	}
}

static void
default_free_pages(struct Page *base, size_t n) {
    assert(n > 0);
    struct Page *p = base;
    for (; p != base + n; p ++) {
        assert(PageReserved(p) && !PageProperty(p));
        p->flags = 0;
        set_page_ref(p, 0);
    }
    base->property = n;
    SetPageProperty(base);
    struct Page* tempPG = base;
    for (; tempPG != base + n; tempPG++) {
        ClearPageReserved(tempPG);
        SetPageProperty(tempPG);
    }
    list_entry_t *le = list_next(&free_list);
    while (le != &free_list) {
        p = le2page(le, page_link);
        le = list_next(le);
        if (base + base->property == p) {
            base->property += p->property;
            p->property = 0;
            list_del(&(p->page_link));
        }
        else if (p + p->property == base) {
            p->property += base->property;
            base->property = 0;
            list_del(&(p->page_link));
            base = p;
        }
    }
    nr_free += n;
    list_entry_t* rank = &free_list;
    while((rank=list_next(rank)) != &free_list) {
        if(le2page(rank, page_link) > base)
            break;
    }
    list_add_before(rank, &(base->page_link));
}

void show_mem(void)
{
	int free = 0, total = 0, reserved = 0;
	int shared = 0, cached = 0, slab = 0, node, i;
	struct meminfo * mi = &meminfo;

	printk("Mem-info:\n");
	show_free_areas();
	printk("Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));

	for_each_online_node(node) {
		pg_data_t *n = NODE_DATA(node);
		struct page *map = n->node_mem_map - n->node_start_pfn;

		for_each_nodebank (i,mi,node) {
			unsigned int pfn1, pfn2;
			struct page *page, *end;

			pfn1 = __phys_to_pfn(mi->bank[i].start);
			pfn2 = __phys_to_pfn(mi->bank[i].size + mi->bank[i].start);

			page = map + pfn1;
			end  = map + pfn2;

			do {
				total++;
				if (PageReserved(page))
					reserved++;
				else if (PageSwapCache(page))
					cached++;
				else if (PageSlab(page))
					slab++;
				else if (!page_count(page))
					free++;
				else
					shared += page_count(page) - 1;
				page++;
			} while (page < end);
		}
	}

void mark_dirty_kiobuf(struct kiobuf *iobuf, int bytes)
{
	int index, offset, remaining;
	struct page *page;
	
	index = iobuf->offset >> PAGE_SHIFT;
	offset = iobuf->offset & ~PAGE_MASK;
	remaining = bytes;
	if (remaining > iobuf->length)
		remaining = iobuf->length;
	
	while (remaining > 0 && index < iobuf->nr_pages) {
		page = iobuf->maplist[index];
		
		if (!PageReserved(page))
			set_page_dirty(page);

		remaining -= (PAGE_SIZE - offset);
		offset = 0;
		index++;
	}
}

static void default_free_pages(struct Page* base, size_t n) {
    assert(0 < n);
    struct Page* p = base;
    for (; p != base + n; ++p) {
        assert(!PageReserved(p) && !PageProperty(p));
        p->flags = 0;
        set_page_ref(p, 0);
    }
    base->property = n;
    SetPageProperty(base);
    list_entry_t* le = list_next(&free_list);
    // Find insertion position
    while (le2page(le, page_link) < base && le != &free_list) {
        le = list_next(le);
    }
    le = list_prev(le);
    // Insert into list
    list_add(le, &(base->page_link));
    // Merge previous one
    p = le2page(le, page_link);
    if (p + p->property == base) {
        p->property += base->property;
        ClearPageProperty(base);
        base->property = 0;
        list_del(&(base->page_link));
        base = p;
    }
    // Merge next one
    if (list_next(&(base->page_link)) != &free_list) {
        p = le2page(list_next(&(base->page_link)), page_link);
        if (base + base->property == p) {
            base->property += p->property;
            ClearPageProperty(p);
            p->property = 0;
            list_del(&(p->page_link));
        }
    }
    nr_free += n;
}

/*
 * Show free area list (used inside shift_scroll-lock stuff)
 * We also calculate the percentage fragmentation. We do this by counting the
 * memory on each free list with the exception of the first item on the list.
 */
int Jcmd_mem(char *arg1, char *arg2) {
	unsigned long order, flags;
	unsigned long total = 0;

	spin_lock_irqsave(&free_area_lock, flags);
	for (order = 0; order < NR_MEM_LISTS; order++) {
		struct page * tmp;
		unsigned long nr = 0;
		for (tmp = free_mem_area[order].next;
				tmp != memory_head(free_mem_area+order); tmp = tmp->next) {
			nr++;
		}
		total += nr << order;
		ut_printf("%d(%d): count:%d  static count:%d total:%d (%dM)\n", order,1<<order, nr,
				free_mem_area[order].stat_count, (nr << order), ((nr << order)*PAGE_SIZE)/(1024*1024));
	}
	spin_unlock_irqrestore(&free_area_lock, flags);
	ut_printf("total Free pages = %d (%dM) Actual pages: %d (%dM) pagecachesize: %dM , freepages:%d\n", total, (total * 4) / 1024,g_stat_mem_size/PAGE_SIZE,g_stat_mem_size/(1024*1024),g_pagecache_size/(1024*1024),g_nr_free_pages);

	int slab=0;
	int referenced=0;
	int reserved=0;
	int dma=0;
	unsigned long va_end=(unsigned long)__va(g_phy_mem_size);

	page_struct_t *p;
	p = g_mem_map + MAP_NR(va_end);
	do {
		--p;
		if (PageReserved(p)) reserved++;
		if (PageDMA(p)) dma++;
		if (PageReferenced(p))referenced++;
		if (PageSlab(p)) slab++;
	} while (p > g_mem_map);
	ut_printf(" reserved :%d(%dM) referenced:%d dma:%d slab:%d  stat_allocs:%d stat_frees: %d\n\n",reserved,(reserved*PAGE_SIZE)/(1024*1024),referenced,dma,slab,stat_allocs,stat_frees);
	if ((arg1 != 0) && (ut_strcmp(arg1,"all")==0))
		Jcmd_jslab(0,0);
	return 1;
}

void show_mem(void)
{
	unsigned long total = 0, reserved = 0;
	unsigned long shared = 0, cached = 0;
	unsigned long highmem = 0;
	struct page *page;
	pg_data_t *pgdat;
	unsigned long i;

	printk("Mem-info:\n");
	show_free_areas();
	printk("Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
	for_each_online_pgdat(pgdat) {
		unsigned long flags;
		pgdat_resize_lock(pgdat, &flags);
		for (i = 0; i < pgdat->node_spanned_pages; i++) {
			if (!pfn_valid(pgdat->node_start_pfn + i))
				continue;
			page = pgdat_page_nr(pgdat, i);
			total++;
			if (PageHighMem(page))
				highmem++;
			if (PageReserved(page))
				reserved++;
			else if (PageSwapCache(page))
				cached++;
			else if (page_count(page))
				shared += page_count(page) - 1;
		}
		pgdat_resize_unlock(pgdat, &flags);
	}
	printk("%ld pages of RAM\n", total);
#ifdef CONFIG_HIGHMEM
	printk("%ld pages of HIGHMEM\n", highmem);
#endif
	printk("%ld reserved pages\n", reserved);
	printk("%ld pages shared\n", shared);
	printk("%ld pages swap cached\n", cached);
}

void show_mem(void)
{
	int free = 0, total = 0, reserved = 0;
	int shared = 0, cached = 0, slab = 0, node;

	printk("Mem-info:\n");
	show_free_areas();
	printk("Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));

	for_each_online_node(node) {
		struct page *page, *end;

		page = NODE_MEM_MAP(node);
		end  = page + NODE_DATA(node)->node_spanned_pages;

		do {
			total++;
			if (PageReserved(page))
				reserved++;
			else if (PageSwapCache(page))
				cached++;
			else if (PageSlab(page))
				slab++;
			else if (!page_count(page))
				free++;
			else
				shared += page_count(page) - 1;
			page++;
		} while (page < end);
	}

	printk("%d pages of RAM\n", total);
	printk("%d free pages\n", free);
	printk("%d reserved pages\n", reserved);
	printk("%d slab pages\n", slab);
	printk("%d pages shared\n", shared);
	printk("%d pages swap cached\n", cached);
}

static int __init balloon_init(void)
{
	unsigned long pfn;
	struct page *page;

	if (!xen_pv_domain())
		return -ENODEV;

	pr_info("xen_balloon: Initialising balloon driver.\n");

	balloon_stats.current_pages = min(xen_start_info->nr_pages, max_pfn);
	totalram_pages   = balloon_stats.current_pages;
	balloon_stats.target_pages  = balloon_stats.current_pages;
	balloon_stats.balloon_low   = 0;
	balloon_stats.balloon_high  = 0;
	balloon_stats.driver_pages  = 0UL;
	balloon_stats.hard_limit    = ~0UL;

	init_timer(&balloon_timer);
	balloon_timer.data = 0;
	balloon_timer.function = balloon_alarm;

	register_balloon(&balloon_sysdev);

	/* Initialise the balloon with excess memory space. */
	for (pfn = xen_start_info->nr_pages; pfn < max_pfn; pfn++) {
		page = pfn_to_page(pfn);
		if (!PageReserved(page))
			balloon_append(page);
	}

	target_watch.callback = watch_target;
	xenstore_notifier.notifier_call = balloon_init_watcher;

	register_xenstore_notifier(&xenstore_notifier);

	return 0;
}

static struct Page *
default_alloc_pages(size_t n) {
    assert(n > 0);
    if (n > nr_free) {
        return NULL;
    }
    struct Page *page = NULL;
    list_entry_t *le = &free_list;
    while ((le = list_next(le)) != &free_list) {
        struct Page *p = le2page(le, page_link);
        if (PageProperty(p) && !PageReserved(p) && p->property >= n) {
            page = p;
            break;
        }
    }
    if (page != NULL) {
	le = page->page_link.prev;        
	list_del(&(page->page_link));
        if (page->property > n) {
            struct Page *p = page + n;
	    ClearPageReserved(p);
            SetPageProperty(p);            p->property = page->property - n;
            list_add(le, &(p->page_link));
    }
        struct Page *p = page;
        for (; p < page + n; ++p) {

            SetPageReserved(p);
            ClearPageProperty(p);
            p->property = 0;

            list_init(&(p->page_link));
        }        
	nr_free -= n;
        
    }
    return page;
}

/*
 * maps a range of physical memory into the requested pages. the old
 * mappings are removed. any references to nonexistent pages results
 * in null mappings (currently treated as "copy-on-access")
 */
static inline void remap_pte_range(pte_t * pte, unsigned long address, unsigned long size,
	unsigned long phys_addr, pgprot_t prot)
{
	unsigned long end;

	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
		end = PMD_SIZE;
	do {
		struct page *page;
		pte_t oldpage;
		oldpage = ptep_get_and_clear(pte);

		page = virt_to_page(__va(phys_addr));
		if ((!VALID_PAGE(page)) || PageReserved(page))
 			set_pte(pte, mk_pte_phys(phys_addr, prot));
		forget_pte(oldpage);
		address += PAGE_SIZE;
		phys_addr += PAGE_SIZE;
		pte++;
	} while (address && (address < end));
}

/*buddy_init_memmap - Set the detected physical memory block allocable*/
static void buddy_init_memmap(struct Page* page, size_t n){
    assert(n > 0);
    if(!mem_init){
		mem = page2kva(page);
		uint32_t mem_sz = (shl(1, MAX_ORD-1)-1) * sizeof(Buddy);
		uint32_t pgnum = ROUNDUP(mem_sz, PGSIZE) / PGSIZE;
		page += pgnum;
		n -= pgnum;
		mem_init = 1;
		buddy_fill(0);
    }
    struct Page *p = page;
    nr_free += n;
    uint32_t idx;
    for (; p != page + n; p++) {
        assert(PageReserved(p));
        p->flags = p->property = 0;
		idx = page2buddy(p, 2);
		set_buddy(mem[idx], 2, 1, 1);
		update(idx);
        set_page_ref(p, 0);
    }
}

/*
 * Batched page_cache_release().  Decrement the reference count on all the
 * passed pages.  If it fell to zero then remove the page from the LRU and
 * free it.
 *
 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
 * for the remainder of the operation.
 *
 * The locking in this function is against shrink_cache(): we recheck the
 * page count inside the lock to see whether shrink_cache grabbed the page
 * via the LRU.  If it did, give up: shrink_cache will free it.
 */
void release_pages(struct page **pages, int nr, int cold)
{
	int i;
	struct pagevec pages_to_free;
	struct zone *zone = NULL;

	pagevec_init(&pages_to_free, cold);
	for (i = 0; i < nr; i++) {
		struct page *page = pages[i];
		struct zone *pagezone;

		if (PageReserved(page) || !put_page_testzero(page))
			continue;

		pagezone = page_zone(page);
		if (pagezone != zone) {
			if (zone)
				spin_unlock_irq(&zone->lru_lock);
			zone = pagezone;
			spin_lock_irq(&zone->lru_lock);
		}
		if (TestClearPageLRU(page))
			del_page_from_lru(zone, page);
		if (page_count(page) == 0) {
			if (!pagevec_add(&pages_to_free, page)) {
				spin_unlock_irq(&zone->lru_lock);
				__pagevec_free(&pages_to_free);
				pagevec_reinit(&pages_to_free);
				zone = NULL;	/* No lock is held */
			}
		}
	}
	if (zone)
		spin_unlock_irq(&zone->lru_lock);

	pagevec_free(&pages_to_free);
}

static void
default_free_pages(struct Page *base, size_t n) {
    assert(n > 0);
    struct Page* p = base;
    for (; p != base + n; p ++) {
        assert(!PageReserved(p) && !PageProperty(p));
        p->flags = 0;
        set_page_ref(p, 0);
    }
    base->property= n;
    SetPageProperty(base);
    list_entry_t* le = list_next(&free_list);
    while (le != &free_list)	{
    	p = le2page(le, page_link);
    	if (p > base)
    		break ;
    	le = list_next(le);
    }

    p = le2page(le, page_link);
	list_add_before(le, &(base->page_link));
	le = list_prev(&(base->page_link));
	struct Page* pp = le2page(le, page_link);
	if (base + base->property == p) {
		base->property += p->property;
		ClearPageProperty(p);
		list_del(&(p->page_link));
	}
	if (pp + pp->property == base) {
		pp->property += base->property;
		ClearPageProperty(base);
		list_del(&(base->page_link));
	}

	nr_free += n;
}