/*
 * Copyright (c) 2001-2005 Jakub Jermar
 * Copyright (c) 2005 Sergey Bondari
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup genericmm
 * @{
 */

/**
 * @file
 * @brief	Physical frame allocator.
 *
 * This file contains the physical frame allocator and memory zone management.
 * The frame allocator is built on top of the buddy allocator.
 *
 * @see buddy.c
 */

/*
 * Locking order
 *
 * In order to access particular zone, the process must first lock
 * the zones.lock, then lock the zone and then unlock the zones.lock.
 * This insures, that we can fiddle with the zones in runtime without
 * affecting the processes. 
 *
 */

#include <arch/types.h>
#include <mm/frame.h>
#include <mm/as.h>
#include <panic.h>
#include <debug.h>
#include <adt/list.h>
#include <synch/spinlock.h>
#include <synch/mutex.h>
#include <synch/condvar.h>
#include <arch/asm.h>
#include <arch.h>
#include <print.h>
#include <align.h>
#include <mm/slab.h>
#include <bitops.h>
#include <macros.h>
#include <config.h>

typedef struct {
	count_t refcount;	/**< tracking of shared frames  */
	uint8_t buddy_order;	/**< buddy system block order */
	link_t buddy_link;	/**< link to the next free block inside one
				     order */
	void *parent;           /**< If allocated by slab, this points there */
} frame_t;

typedef struct {
	SPINLOCK_DECLARE(lock);	/**< this lock protects everything below */
	pfn_t base;		/**< frame_no of the first frame in the frames
				     array */
	count_t count;          /**< Size of zone */

	frame_t *frames;	/**< array of frame_t structures in this
				     zone */
	count_t free_count;	/**< number of free frame_t structures */
	count_t busy_count;	/**< number of busy frame_t structures */
	
	buddy_system_t *buddy_system; /**< buddy system for the zone */
	int flags;
} zone_t;

/*
 * The zoneinfo.lock must be locked when accessing zoneinfo structure.
 * Some of the attributes in zone_t structures are 'read-only'
 */

typedef struct {
	SPINLOCK_DECLARE(lock);
	unsigned int count;
	zone_t *info[ZONES_MAX];
} zones_t;

static zones_t zones;

/*
 * Synchronization primitives used to sleep when there is no memory
 * available.
 */
mutex_t mem_avail_mtx;
condvar_t mem_avail_cv;
unsigned long mem_avail_frames = 0;	/**< Number of available frames. */
unsigned long mem_avail_gen = 0;	/**< Generation counter. */

/********************/
/* Helper functions */
/********************/

static inline index_t frame_index(zone_t *zone, frame_t *frame)
{
	return (index_t) (frame - zone->frames);
}

static inline index_t frame_index_abs(zone_t *zone, frame_t *frame)
{
	return (index_t) (frame - zone->frames) + zone->base;
}

static inline int frame_index_valid(zone_t *zone, index_t index)
{
	return (index < zone->count);
}

/** Compute pfn_t from frame_t pointer & zone pointer */
static index_t make_frame_index(zone_t *zone, frame_t *frame)
{
	return (frame - zone->frames);
}

/** Initialize frame structure.
 *
 * @param frame		Frame structure to be initialized.
 */
static void frame_initialize(frame_t *frame)
{
	frame->refcount = 1;
	frame->buddy_order = 0;
}

/**********************/
/* Zoneinfo functions */
/**********************/

/** Insert-sort zone into zones list.
 *
 * @param newzone	New zone to be inserted into zone list.
 * @return		Zone number on success, -1 on error.
 */
static int zones_add_zone(zone_t *newzone)
{
	unsigned int i, j;
	ipl_t ipl;
	zone_t *z;

	ipl = interrupts_disable();
	spinlock_lock(&zones.lock);
	
	/* Try to merge */
	if (zones.count + 1 == ZONES_MAX) {
		printf("Maximum zone count %u exceeded!\n", ZONES_MAX);
		spinlock_unlock(&zones.lock);
		interrupts_restore(ipl);
		return -1;
	}
	
	for (i = 0; i < zones.count; i++) {
		/* Check for overflow */
		z = zones.info[i];
		if (overlaps(newzone->base, newzone->count, z->base,
		    z->count)) {
			printf("Zones overlap!\n");
			return -1;
		}
		if (newzone->base < z->base)
			break;
	}
	
	/* Move other zones up */
	for (j = i; j < zones.count; j++)
		zones.info[j + 1] = zones.info[j];
	
	zones.info[i] = newzone;
	zones.count++;
	
	spinlock_unlock(&zones.lock);
	interrupts_restore(ipl);

	return i;
}

/** Try to find a zone where can we find the frame.
 *
 * Assume interrupts are disabled.
 *
 * @param frame		Frame number contained in zone.
 * @param pzone		If not null, it is used as zone hint. Zone index is
 * 			filled into the variable on success. 
 * @return		Pointer to locked zone containing frame.
 */
static zone_t *find_zone_and_lock(pfn_t frame, unsigned int *pzone)
{
	unsigned int i;
	unsigned int hint = pzone ? *pzone : 0;
	zone_t *z;
	
	spinlock_lock(&zones.lock);

	if (hint >= zones.count)
		hint = 0;
	
	i = hint;
	do {
		z = zones.info[i];
		spinlock_lock(&z->lock);
		if (z->base <= frame && z->base + z->count > frame) {
			/* Unlock the global lock */
			spinlock_unlock(&zones.lock); 
			if (pzone)
				*pzone = i;
			return z;
		}
		spinlock_unlock(&z->lock);

		i++;
		if (i >= zones.count)
			i = 0;
	} while (i != hint);

	spinlock_unlock(&zones.lock);
	return NULL;
}

/** @return True if zone can allocate specified order */
static int zone_can_alloc(zone_t *z, uint8_t order)
{
	return buddy_system_can_alloc(z->buddy_system, order);
}

/** Find and lock zone that can allocate order frames.
 *
 * Assume interrupts are disabled.
 *
 * @param order		Size (2^order) of free space we are trying to find.
 * @param flags		Required flags of the target zone.
 * @param pzone		Pointer to preferred zone or NULL, on return contains
 * 			zone number.
 */
static zone_t *
find_free_zone_and_lock(uint8_t order, int flags, unsigned int *pzone)
{
	unsigned int i;
	zone_t *z;
	unsigned int hint = pzone ? *pzone : 0;
	
	/* Mask off flags that are not applicable. */
	flags &= FRAME_LOW_4_GiB;

	spinlock_lock(&zones.lock);
	if (hint >= zones.count)
		hint = 0;
	i = hint;
	do {
		z = zones.info[i];
		
		spinlock_lock(&z->lock);

		/*
		 * Check whether the zone meets the search criteria.
		 */
		if ((z->flags & flags) == flags) {
			/*
			 * Check if the zone has 2^order frames area available.
			 */
			if (zone_can_alloc(z, order)) {
				spinlock_unlock(&zones.lock);
				if (pzone)
					*pzone = i;
				return z;
			}
		}
		spinlock_unlock(&z->lock);
		if (++i >= zones.count)
			i = 0;
	} while (i != hint);
	spinlock_unlock(&zones.lock);
	return NULL;
}

/**************************/
/* Buddy system functions */
/**************************/

/** Buddy system find_block implementation.
 *
 * Find block that is parent of current list.
 * That means go to lower addresses, until such block is found
 *
 * @param order		Order of parent must be different then this
 * 			parameter!!
 */
static link_t *zone_buddy_find_block(buddy_system_t *b, link_t *child,
    uint8_t order)
{
	frame_t *frame;
	zone_t *zone;
	index_t index;
	
	frame = list_get_instance(child, frame_t, buddy_link);
	zone = (zone_t *) b->data;

	index = frame_index(zone, frame);
	do {
		if (zone->frames[index].buddy_order != order) {
			return &zone->frames[index].buddy_link;
		}
	} while(index-- > 0);
	return NULL;
}

/** Buddy system find_buddy implementation.
 *
 * @param b		Buddy system.
 * @param block		Block for which buddy should be found.
 *
 * @return		Buddy for given block if found.
 */
static link_t *zone_buddy_find_buddy(buddy_system_t *b, link_t *block) 
{
	frame_t *frame;
	zone_t *zone;
	index_t index;
	bool is_left, is_right;

	frame = list_get_instance(block, frame_t, buddy_link);
	zone = (zone_t *) b->data;
	ASSERT(IS_BUDDY_ORDER_OK(frame_index_abs(zone, frame),
	    frame->buddy_order));
	
	is_left = IS_BUDDY_LEFT_BLOCK_ABS(zone, frame);
	is_right = IS_BUDDY_RIGHT_BLOCK_ABS(zone, frame);

	ASSERT(is_left ^ is_right);
	if (is_left) {
		index = (frame_index(zone, frame)) +
		    (1 << frame->buddy_order);
	} else { 	/* if (is_right) */
		index = (frame_index(zone, frame)) -
		    (1 << frame->buddy_order);
	}
	
	if (frame_index_valid(zone, index)) {
		if (zone->frames[index].buddy_order == frame->buddy_order && 
		    zone->frames[index].refcount == 0) {
			return &zone->frames[index].buddy_link;
		}
	}

	return NULL;	
}

/** Buddy system bisect implementation.
 *
 * @param b		Buddy system.
 * @param block		Block to bisect.
 *
 * @return		Right block.
 */
static link_t *zone_buddy_bisect(buddy_system_t *b, link_t *block)
{
	frame_t *frame_l, *frame_r;

	frame_l = list_get_instance(block, frame_t, buddy_link);
	frame_r = (frame_l + (1 << (frame_l->buddy_order - 1)));
	
	return &frame_r->buddy_link;
}

/** Buddy system coalesce implementation.
 *
 * @param b		Buddy system.
 * @param block_1	First block.
 * @param block_2	First block's buddy.
 *
 * @return		Coalesced block (actually block that represents lower
 * 			address).
 */
static link_t *zone_buddy_coalesce(buddy_system_t *b, link_t *block_1, 
    link_t *block_2) 
{
	frame_t *frame1, *frame2;
	
	frame1 = list_get_instance(block_1, frame_t, buddy_link);
	frame2 = list_get_instance(block_2, frame_t, buddy_link);
	
	return frame1 < frame2 ? block_1 : block_2;
}

/** Buddy system set_order implementation.
 *
 * @param b		Buddy system.
 * @param block		Buddy system block.
 * @param order		Order to set.
 */
static void zone_buddy_set_order(buddy_system_t *b, link_t *block,
    uint8_t order)
{
	frame_t *frame;
	frame = list_get_instance(block, frame_t, buddy_link);
	frame->buddy_order = order;
}

/** Buddy system get_order implementation.
 *
 * @param b		Buddy system.
 * @param block		Buddy system block.
 *
 * @return		Order of block.
 */
static uint8_t zone_buddy_get_order(buddy_system_t *b, link_t *block)
{
	frame_t *frame;
	frame = list_get_instance(block, frame_t, buddy_link);
	return frame->buddy_order;
}

/** Buddy system mark_busy implementation.
 *
 * @param b		Buddy system.
 * @param block		Buddy system block.
 */
static void zone_buddy_mark_busy(buddy_system_t *b, link_t * block)
{
	frame_t * frame;

	frame = list_get_instance(block, frame_t, buddy_link);
	frame->refcount = 1;
}

/** Buddy system mark_available implementation.
 *
 * @param b		Buddy system.
 * @param block		Buddy system block.
 */
static void zone_buddy_mark_available(buddy_system_t *b, link_t *block)
{
	frame_t *frame;
	frame = list_get_instance(block, frame_t, buddy_link);
	frame->refcount = 0;
}

static buddy_system_operations_t zone_buddy_system_operations = {
	.find_buddy = zone_buddy_find_buddy,
	.bisect = zone_buddy_bisect,
	.coalesce = zone_buddy_coalesce,
	.set_order = zone_buddy_set_order,
	.get_order = zone_buddy_get_order,
	.mark_busy = zone_buddy_mark_busy,
	.mark_available = zone_buddy_mark_available,
	.find_block = zone_buddy_find_block
};

/******************/
/* Zone functions */
/******************/

/** Allocate frame in particular zone.
 *
 * Assume zone is locked.
 * Panics if allocation is impossible.
 *
 * @param zone		Zone to allocate from.
 * @param order		Allocate exactly 2^order frames.
 *
 * @return		Frame index in zone.
 *
 */
static pfn_t zone_frame_alloc(zone_t *zone, uint8_t order)
{
	pfn_t v;
	link_t *tmp;
	frame_t *frame;

	/* Allocate frames from zone buddy system */
	tmp = buddy_system_alloc(zone->buddy_system, order);
	
	ASSERT(tmp);
	
	/* Update zone information. */
	zone->free_count -= (1 << order);
	zone->busy_count += (1 << order);

	/* Frame will be actually a first frame of the block. */
	frame = list_get_instance(tmp, frame_t, buddy_link);
	
	/* get frame address */
	v = make_frame_index(zone, frame);
	return v;
}

/** Free frame from zone.
 *
 * Assume zone is locked.
 *
 * @param zone		Pointer to zone from which the frame is to be freed.
 * @param frame_idx	Frame index relative to zone.
 */
static void zone_frame_free(zone_t *zone, index_t frame_idx)
{
	frame_t *frame;
	uint8_t order;

	frame = &zone->frames[frame_idx];
	
	/* remember frame order */
	order = frame->buddy_order;

	ASSERT(frame->refcount);

	if (!--frame->refcount) {
		buddy_system_free(zone->buddy_system, &frame->buddy_link);
	
		/* Update zone information. */
		zone->free_count += (1 << order);
		zone->busy_count -= (1 << order);
	}
}

/** Return frame from zone. */
static frame_t *zone_get_frame(zone_t *zone, index_t frame_idx)
{
	ASSERT(frame_idx < zone->count);
	return &zone->frames[frame_idx];
}

/** Mark frame in zone unavailable to allocation. */
static void zone_mark_unavailable(zone_t *zone, index_t frame_idx)
{
	frame_t *frame;
	link_t *link;

	frame = zone_get_frame(zone, frame_idx);
	if (frame->refcount)
		return;
	link = buddy_system_alloc_block(zone->buddy_system,
	    &frame->buddy_link);
	ASSERT(link);
	zone->free_count--;

	mutex_lock(&mem_avail_mtx);
	mem_avail_frames--;
	mutex_unlock(&mem_avail_mtx);
}

/** Join two zones.
 *
 * Expect zone_t *z to point to space at least zone_conf_size large.
 *
 * Assume z1 & z2 are locked.
 *
 * @param z		Target zone structure pointer.
 * @param z1		Zone to merge.
 * @param z2		Zone to merge.
 */
static void _zone_merge(zone_t *z, zone_t *z1, zone_t *z2)
{
	uint8_t max_order;
	unsigned int i;
	int z2idx;
	pfn_t frame_idx;
	frame_t *frame;

	ASSERT(!overlaps(z1->base, z1->count, z2->base, z2->count));
	ASSERT(z1->base < z2->base);

	spinlock_initialize(&z->lock, "zone_lock");
	z->base = z1->base;
	z->count = z2->base + z2->count - z1->base;
	z->flags = z1->flags & z2->flags;

	z->free_count = z1->free_count + z2->free_count;
	z->busy_count = z1->busy_count + z2->busy_count;
	
	max_order = fnzb(z->count);

	z->buddy_system = (buddy_system_t *) &z[1];
	buddy_system_create(z->buddy_system, max_order,
	    &zone_buddy_system_operations, (void *) z);

	z->frames = (frame_t *)((uint8_t *) z->buddy_system +
	    buddy_conf_size(max_order));
	for (i = 0; i < z->count; i++) {
		/* This marks all frames busy */
		frame_initialize(&z->frames[i]);
	}
	/* Copy frames from both zones to preserve full frame orders,
	 * parents etc. Set all free frames with refcount=0 to 1, because
	 * we add all free frames to buddy allocator later again, clear
	 * order to 0. Don't set busy frames with refcount=0, as they
	 * will not be reallocated during merge and it would make later
	 * problems with allocation/free.
	 */
	for (i = 0; i < z1->count; i++)
		z->frames[i] = z1->frames[i];
	for (i = 0; i < z2->count; i++) {
		z2idx = i + (z2->base - z1->base);
		z->frames[z2idx] = z2->frames[i];
	}
	i = 0;
	while (i < z->count) {
		if (z->frames[i].refcount) {
			/* skip busy frames */
			i += 1 << z->frames[i].buddy_order;
		} else { /* Free frames, set refcount=1 */
			/* All free frames have refcount=0, we need not
			 * to check the order */
			z->frames[i].refcount = 1;
			z->frames[i].buddy_order = 0;
			i++;
		}
	}
	/* Add free blocks from the 2 original zones */
	while (zone_can_alloc(z1, 0)) {
		frame_idx = zone_frame_alloc(z1, 0);
		frame = &z->frames[frame_idx];
		frame->refcount = 0;
		buddy_system_free(z->buddy_system, &frame->buddy_link);
	}
	while (zone_can_alloc(z2, 0)) {
		frame_idx = zone_frame_alloc(z2, 0);
		frame = &z->frames[frame_idx + (z2->base - z1->base)];
		frame->refcount = 0;
		buddy_system_free(z->buddy_system, &frame->buddy_link);
	}
}

/** Return old configuration frames into the zone.
 *
 * We have several cases
 * - the conf. data is outside of zone -> exit, shall we call frame_free??
 * - the conf. data was created by zone_create or 
 *   updated with reduce_region -> free every frame
 *
 * @param newzone	The actual zone where freeing should occur.
 * @param oldzone	Pointer to old zone configuration data that should
 * 			be freed from new zone.
 */
static void return_config_frames(zone_t *newzone, zone_t *oldzone)
{
	pfn_t pfn;
	frame_t *frame;
	count_t cframes;
	unsigned int i;

	pfn = ADDR2PFN((uintptr_t)KA2PA(oldzone));
	cframes = SIZE2FRAMES(zone_conf_size(oldzone->count));
	
	if (pfn < newzone->base || pfn >= newzone->base + newzone->count)
		return;

	frame = &newzone->frames[pfn - newzone->base];
	ASSERT(!frame->buddy_order);

	for (i = 0; i < cframes; i++) {
		newzone->busy_count++;
		zone_frame_free(newzone, pfn+i-newzone->base);
	}
}

/** Reduce allocated block to count of order 0 frames.
 *
 * The allocated block need 2^order frames of space. Reduce all frames
 * in block to order 0 and free the unneeded frames. This means, that 
 * when freeing the previously allocated block starting with frame_idx, 
 * you have to free every frame.
 *
 * @param zone 
 * @param frame_idx		Index to block.
 * @param count			Allocated space in block.
 */
static void zone_reduce_region(zone_t *zone, pfn_t frame_idx, count_t count)
{
	count_t i;
	uint8_t order;
	frame_t *frame;
	
	ASSERT(frame_idx + count < zone->count);

	order = zone->frames[frame_idx].buddy_order;
	ASSERT((count_t) (1 << order) >= count);

	/* Reduce all blocks to order 0 */
	for (i = 0; i < (count_t) (1 << order); i++) {
		frame = &zone->frames[i + frame_idx];
		frame->buddy_order = 0;
		if (!frame->refcount)
			frame->refcount = 1;
		ASSERT(frame->refcount == 1);
	}
	/* Free unneeded frames */
	for (i = count; i < (count_t) (1 << order); i++) {
		zone_frame_free(zone, i + frame_idx);
	}
}

/** Merge zones z1 and z2.
 *
 * - the zones must be 2 zones with no zone existing in between,
 *   which means that z2 = z1+1
 *
 * - When you create a new zone, the frame allocator configuration does
 *   not to be 2^order size. Once the allocator is running it is no longer
 *   possible, merged configuration data occupies more space :-/
 */
void zone_merge(unsigned int z1, unsigned int z2)
{
	ipl_t ipl;
	zone_t *zone1, *zone2, *newzone;
	unsigned int cframes;
	uint8_t order;
	unsigned int i;
	pfn_t pfn;

	ipl = interrupts_disable();
	spinlock_lock(&zones.lock);

	if ((z1 >= zones.count) || (z2 >= zones.count))
		goto errout;
	/* We can join only 2 zones with none existing inbetween */
	if (z2 - z1 != 1)
		goto errout;

	zone1 = zones.info[z1];
	zone2 = zones.info[z2];
	spinlock_lock(&zone1->lock);
	spinlock_lock(&zone2->lock);

	cframes = SIZE2FRAMES(zone_conf_size(zone2->base + zone2->count -
	    zone1->base));
	if (cframes == 1)
		order = 0;
	else 
		order = fnzb(cframes - 1) + 1;

	/* Allocate zonedata inside one of the zones */
	if (zone_can_alloc(zone1, order))
		pfn = zone1->base + zone_frame_alloc(zone1, order);
	else if (zone_can_alloc(zone2, order))
		pfn = zone2->base + zone_frame_alloc(zone2, order);
	else
		goto errout2;

	newzone = (zone_t *) PA2KA(PFN2ADDR(pfn));

	_zone_merge(newzone, zone1, zone2);

	/* Free unneeded config frames */
	zone_reduce_region(newzone, pfn - newzone->base,  cframes);
	/* Subtract zone information from busy frames */
	newzone->busy_count -= cframes;

	/* Replace existing zones in zoneinfo list */
	zones.info[z1] = newzone;
	for (i = z2 + 1; i < zones.count; i++)
		zones.info[i - 1] = zones.info[i];
	zones.count--;

	/* Free old zone information */
	return_config_frames(newzone, zone1);
	return_config_frames(newzone, zone2);
errout2:
	/* Nobody is allowed to enter to zone, so we are safe
	 * to touch the spinlocks last time */
	spinlock_unlock(&zone1->lock);
	spinlock_unlock(&zone2->lock);
errout:
	spinlock_unlock(&zones.lock);
	interrupts_restore(ipl);
}

/** Merge all zones into one big zone.
 *
 * It is reasonable to do this on systems whose bios reports parts in chunks,
 * so that we could have 1 zone (it's faster).
 */
void zone_merge_all(void)
{
	int count = zones.count;

	while (zones.count > 1 && --count) {
		zone_merge(0, 1);
		break;
	}
}

/** Create new frame zone.
 *
 * @param start		Physical address of the first frame within the zone.
 * @param count		Count of frames in zone.
 * @param z		Address of configuration information of zone.
 * @param flags		Zone flags.
 *
 * @return		Initialized zone.
 */
static void zone_construct(pfn_t start, count_t count, zone_t *z, int flags)
{
	unsigned int i;
	uint8_t max_order;

	spinlock_initialize(&z->lock, "zone_lock");
	z->base = start;
	z->count = count;

	/* Mask off flags that are calculated automatically. */
	flags &= ~FRAME_LOW_4_GiB;
	/* Determine calculated flags. */
	if (z->base + count < (1ULL << (32 - FRAME_WIDTH)))	/* 4 GiB */
		flags |= FRAME_LOW_4_GiB;

	z->flags = flags;

	z->free_count = count;
	z->busy_count = 0;

	/*
	 * Compute order for buddy system, initialize
	 */
	max_order = fnzb(count);
	z->buddy_system = (buddy_system_t *)&z[1];
	
	buddy_system_create(z->buddy_system, max_order, 
	    &zone_buddy_system_operations, (void *) z);
	
	/* Allocate frames _after_ the conframe */
	/* Check sizes */
	z->frames = (frame_t *)((uint8_t *) z->buddy_system +
	    buddy_conf_size(max_order));
	for (i = 0; i < count; i++) {
		frame_initialize(&z->frames[i]);
	}
	
	/* Stuffing frames */
	for (i = 0; i < count; i++) {
		z->frames[i].refcount = 0;
		buddy_system_free(z->buddy_system, &z->frames[i].buddy_link);
	}
}

/** Compute configuration data size for zone.
 *
 * @param count		Size of zone in frames.
 * @return		Size of zone configuration info (in bytes).
 */
uintptr_t zone_conf_size(count_t count)
{
	int size = sizeof(zone_t) + count * sizeof(frame_t);
	int max_order;

	max_order = fnzb(count);
	size += buddy_conf_size(max_order);
	return size;
}

/** Create and add zone to system.
 *
 * @param start		First frame number (absolute).
 * @param count		Size of zone in frames.
 * @param confframe	Where configuration frames are supposed to be.
 * 			Automatically checks, that we will not disturb the 
 * 			kernel and possibly init.  If confframe is given
 * 			_outside_ this zone, it is expected, that the area is
 * 			already marked BUSY and big enough to contain
 * 			zone_conf_size() amount of data.  If the confframe is
 * 			inside the area, the zone free frame information is
 * 			modified not to include it.
 *
 * @return		Zone number or -1 on error.
 */
int zone_create(pfn_t start, count_t count, pfn_t confframe, int flags)
{
	zone_t *z;
	uintptr_t addr;
	count_t confcount;
	unsigned int i;
	int znum;

	/* Theoretically we could have here 0, practically make sure
	 * nobody tries to do that. If some platform requires, remove
	 * the assert
	 */
	ASSERT(confframe);
	/* If conframe is supposed to be inside our zone, then make sure
	 * it does not span kernel & init
	 */
	confcount = SIZE2FRAMES(zone_conf_size(count));
	if (confframe >= start && confframe < start + count) {
		for (; confframe < start + count; confframe++) {
			addr = PFN2ADDR(confframe);
			if (overlaps(addr, PFN2ADDR(confcount),
			    KA2PA(config.base), config.kernel_size))
				continue;
			
			if (overlaps(addr, PFN2ADDR(confcount),
			    KA2PA(config.stack_base), config.stack_size))
				continue;
			
			bool overlap = false;
			count_t i;
			for (i = 0; i < init.cnt; i++)
				if (overlaps(addr, PFN2ADDR(confcount),
				    KA2PA(init.tasks[i].addr),
				    init.tasks[i].size)) {
					overlap = true;
					break;
				}
			if (overlap)
				continue;
			
			break;
		}
		if (confframe >= start + count)
			panic("Cannot find configuration data for zone.");
	}

	z = (zone_t *) PA2KA(PFN2ADDR(confframe));
	zone_construct(start, count, z, flags);
	znum = zones_add_zone(z);
	if (znum == -1)
		return -1;

	mutex_lock(&mem_avail_mtx);
	mem_avail_frames += count;
	mutex_unlock(&mem_avail_mtx);

	/* If confdata in zone, mark as unavailable */
	if (confframe >= start && confframe < start + count)
		for (i = confframe; i < confframe + confcount; i++) {
			zone_mark_unavailable(z, i - z->base);
		}
	
	return znum;
}

/***************************************/
/* Frame functions */

/** Set parent of frame. */
void frame_set_parent(pfn_t pfn, void *data, unsigned int hint)
{
	zone_t *zone = find_zone_and_lock(pfn, &hint);

	ASSERT(zone);

	zone_get_frame(zone, pfn - zone->base)->parent = data;
	spinlock_unlock(&zone->lock);
}

void *frame_get_parent(pfn_t pfn, unsigned int hint)
{
	zone_t *zone = find_zone_and_lock(pfn, &hint);
	void *res;

	ASSERT(zone);
	res = zone_get_frame(zone, pfn - zone->base)->parent;
	
	spinlock_unlock(&zone->lock);
	return res;
}

/** Allocate power-of-two frames of physical memory.
 *
 * @param order		Allocate exactly 2^order frames.
 * @param flags		Flags for host zone selection and address processing.
 * @param pzone		Preferred zone.
 *
 * @return		Physical address of the allocated frame.
 *
 */
void *frame_alloc_generic(uint8_t order, int flags, unsigned int *pzone)
{
	ipl_t ipl;
	int freed;
	pfn_t v;
	zone_t *zone;
	unsigned long gen = 0;
	
loop:
	ipl = interrupts_disable();
	
	/*
	 * First, find suitable frame zone.
	 */
	zone = find_free_zone_and_lock(order, flags, pzone);
	
	/* If no memory, reclaim some slab memory,
	   if it does not help, reclaim all */
	if (!zone && !(flags & FRAME_NO_RECLAIM)) {
		freed = slab_reclaim(0);
		if (freed)
			zone = find_free_zone_and_lock(order, flags, pzone);
		if (!zone) {
			freed = slab_reclaim(SLAB_RECLAIM_ALL);
			if (freed)
				zone = find_free_zone_and_lock(order, flags,
				    pzone);
		}
	}
	if (!zone) {
		/*
		 * Sleep until some frames are available again.
		 */
		if (flags & FRAME_ATOMIC) {
			interrupts_restore(ipl);
			return 0;
		}
		
#ifdef CONFIG_DEBUG
		unsigned long avail;

		mutex_lock(&mem_avail_mtx);
		avail = mem_avail_frames;
		mutex_unlock(&mem_avail_mtx);

		printf("Thread %" PRIu64 " waiting for %u frames, "
		    "%u available.\n", THREAD->tid, 1ULL << order, avail);
#endif

		mutex_lock(&mem_avail_mtx);
		while ((mem_avail_frames < (1ULL << order)) ||
		    gen == mem_avail_gen)
			condvar_wait(&mem_avail_cv, &mem_avail_mtx);
		gen = mem_avail_gen;
		mutex_unlock(&mem_avail_mtx);

#ifdef CONFIG_DEBUG
		mutex_lock(&mem_avail_mtx);
		avail = mem_avail_frames;
		mutex_unlock(&mem_avail_mtx);

		printf("Thread %" PRIu64 " woken up, %u frames available.\n",
		    THREAD->tid, avail);
#endif

		interrupts_restore(ipl);
		goto loop;
	}
	
	v = zone_frame_alloc(zone, order);
	v += zone->base;

	spinlock_unlock(&zone->lock);
	
	mutex_lock(&mem_avail_mtx);
	mem_avail_frames -= (1ULL << order);
	mutex_unlock(&mem_avail_mtx);

	interrupts_restore(ipl);

	if (flags & FRAME_KA)
		return (void *)PA2KA(PFN2ADDR(v));
	return (void *)PFN2ADDR(v);
}

/** Free a frame.
 *
 * Find respective frame structure for supplied physical frame address.
 * Decrement frame reference count.
 * If it drops to zero, move the frame structure to free list.
 *
 * @param frame		Physical Address of of the frame to be freed.
 */
void frame_free(uintptr_t frame)
{
	ipl_t ipl;
	zone_t *zone;
	pfn_t pfn = ADDR2PFN(frame);

	ipl = interrupts_disable();

	/*
	 * First, find host frame zone for addr.
	 */
	zone = find_zone_and_lock(pfn, NULL);
	ASSERT(zone);
	
	zone_frame_free(zone, pfn - zone->base);
	
	spinlock_unlock(&zone->lock);
	
	/*
	 * Signal that some memory has been freed.
	 */
	mutex_lock(&mem_avail_mtx);
	mem_avail_frames++;
	mem_avail_gen++;
	condvar_broadcast(&mem_avail_cv);
	mutex_unlock(&mem_avail_mtx);

	interrupts_restore(ipl);
}

/** Add reference to frame.
 *
 * Find respective frame structure for supplied PFN and
 * increment frame reference count.
 *
 * @param pfn		Frame number of the frame to be freed.
 */
void frame_reference_add(pfn_t pfn)
{
	ipl_t ipl;
	zone_t *zone;
	frame_t *frame;

	ipl = interrupts_disable();
	
	/*
	 * First, find host frame zone for addr.
	 */
	zone = find_zone_and_lock(pfn, NULL);
	ASSERT(zone);
	
	frame = &zone->frames[pfn - zone->base];
	frame->refcount++;
	
	spinlock_unlock(&zone->lock);
	interrupts_restore(ipl);
}

/** Mark given range unavailable in frame zones. */
void frame_mark_unavailable(pfn_t start, count_t count)
{
	unsigned int i;
	zone_t *zone;
	unsigned int prefzone = 0;
	
	for (i = 0; i < count; i++) {
		zone = find_zone_and_lock(start + i, &prefzone);
		if (!zone) /* PFN not found */
			continue;
		zone_mark_unavailable(zone, start + i - zone->base);

		spinlock_unlock(&zone->lock);
	}
}

/** Initialize physical memory management. */
void frame_init(void)
{
	if (config.cpu_active == 1) {
		zones.count = 0;
		spinlock_initialize(&zones.lock, "zones.lock");
		mutex_initialize(&mem_avail_mtx, MUTEX_ACTIVE);
		condvar_initialize(&mem_avail_cv);
	}
	/* Tell the architecture to create some memory */
	frame_arch_init();
	if (config.cpu_active == 1) {
		frame_mark_unavailable(ADDR2PFN(KA2PA(config.base)),
		    SIZE2FRAMES(config.kernel_size));
		frame_mark_unavailable(ADDR2PFN(KA2PA(config.stack_base)),
		    SIZE2FRAMES(config.stack_size));
		
		count_t i;
		for (i = 0; i < init.cnt; i++) {
			pfn_t pfn = ADDR2PFN(KA2PA(init.tasks[i].addr));
			frame_mark_unavailable(pfn,
			    SIZE2FRAMES(init.tasks[i].size));
		}

		if (ballocs.size)
			frame_mark_unavailable(ADDR2PFN(KA2PA(ballocs.base)),
			    SIZE2FRAMES(ballocs.size));

		/* Black list first frame, as allocating NULL would
		 * fail in some places */
		frame_mark_unavailable(0, 1);
	}
}


/** Return total size of all zones. */
uint64_t zone_total_size(void)
{
	zone_t *zone = NULL;
	unsigned int i;
	ipl_t ipl;
	uint64_t total = 0;

	ipl = interrupts_disable();
	spinlock_lock(&zones.lock);
	
	for (i = 0; i < zones.count; i++) {
		zone = zones.info[i];
		spinlock_lock(&zone->lock);
		total += (uint64_t) FRAMES2SIZE(zone->count);
		spinlock_unlock(&zone->lock);
	}
	
	spinlock_unlock(&zones.lock);
	interrupts_restore(ipl);
	
	return total;
}

/** Prints list of zones. */
void zone_print_list(void)
{
	zone_t *zone = NULL;
	unsigned int i;
	ipl_t ipl;

#ifdef __32_BITS__	
	printf("#  base address free frames  busy frames\n");
	printf("-- ------------ ------------ ------------\n");
#endif

#ifdef __64_BITS__
	printf("#  base address         free frames  busy frames\n");
	printf("-- -------------------- ------------ ------------\n");
#endif
	
	/*
	 * Because printing may require allocation of memory, we may not hold
	 * the frame allocator locks when printing zone statistics.  Therefore,
	 * we simply gather the statistics under the protection of the locks and
	 * print the statistics when the locks have been released.
	 *
	 * When someone adds/removes zones while we are printing the statistics,
	 * we may end up with inaccurate output (e.g. a zone being skipped from
	 * the listing).
	 */

	for (i = 0; ; i++) {
		uintptr_t base;
		count_t free_count;
		count_t busy_count;

		ipl = interrupts_disable();
		spinlock_lock(&zones.lock);
		
		if (i >= zones.count) {
			spinlock_unlock(&zones.lock);
			interrupts_restore(ipl);
			break;
		}

		zone = zones.info[i];
		spinlock_lock(&zone->lock);

		base = PFN2ADDR(zone->base);
		free_count = zone->free_count;
		busy_count = zone->busy_count;

		spinlock_unlock(&zone->lock);
		
		spinlock_unlock(&zones.lock);
		interrupts_restore(ipl);

#ifdef __32_BITS__
		printf("%-2u   %10p %12" PRIc " %12" PRIc "\n", i, base,
		    free_count, busy_count);
#endif

#ifdef __64_BITS__
		printf("%-2u   %18p %12" PRIc " %12" PRIc "\n", i, base,
		    free_count, busy_count);
#endif
		
	}
}

/** Prints zone details.
 *
 * @param num		Zone base address or zone number.
 */
void zone_print_one(unsigned int num)
{
	zone_t *zone = NULL;
	ipl_t ipl;
	unsigned int i;
	uintptr_t base;
	count_t count;
	count_t busy_count;
	count_t free_count;

	ipl = interrupts_disable();
	spinlock_lock(&zones.lock);

	for (i = 0; i < zones.count; i++) {
		if ((i == num) || (PFN2ADDR(zones.info[i]->base) == num)) {
			zone = zones.info[i];
			break;
		}
	}
	if (!zone) {
		spinlock_unlock(&zones.lock);
		interrupts_restore(ipl);
		printf("Zone not found.\n");
		return;
	}
	
	spinlock_lock(&zone->lock);
	base = PFN2ADDR(zone->base);
	count = zone->count;
	busy_count = zone->busy_count;
	free_count = zone->free_count;
	spinlock_unlock(&zone->lock);
	spinlock_unlock(&zones.lock);
	interrupts_restore(ipl);

	printf("Zone base address: %p\n", base);
	printf("Zone size: %" PRIc " frames (%" PRIs " KiB)\n", count,
	    SIZE2KB(FRAMES2SIZE(count)));
	printf("Allocated space: %" PRIc " frames (%" PRIs " KiB)\n",
	    busy_count, SIZE2KB(FRAMES2SIZE(busy_count)));
	printf("Available space: %" PRIc " frames (%" PRIs " KiB)\n",
	    free_count, SIZE2KB(FRAMES2SIZE(free_count)));
}

/** @}
 */