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/*

 * 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 <arch/asm.h>

#include <arch.h>

#include <print.h>

#include <align.h>

#include <mm/slab.h>

#include <bitops.h>

#include <macros.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;

/*********************************/

/* 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 >= 0 && 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

 *

 * 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)

		panic("Maximum zone(%d) count exceeded.", ZONES_MAX);

	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)

		hint = 0;

	i = hint;

	do {

		z = zones.info[i];

		spinlock_lock(&z->lock);

		if (z->base <= frame && z->base + z->count > frame) {

			spinlock_unlock(&zones.lock); /* Unlock the global 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 pzone Pointer to preferred zone or NULL, on return contains zone number

 */

static zone_t * find_free_zone_and_lock(uint8_t order, int *pzone)

{

	unsigned int i;

	zone_t *z;

	unsigned int hint = pzone ? *pzone : 0;

	spinlock_lock(&zones.lock);

	if (hint >= zones.count)

		hint = 0;

	i = hint;

	do {

		z = zones.info[i];

		spinlock_lock(&z->lock);

		/* 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;

}

static void zone_buddy_print_id(buddy_system_t *b, link_t *block)

{

	frame_t * frame;

	zone_t * zone;

	index_t index;

	frame = list_get_instance(block, frame_t, buddy_link);

	zone = (zone_t *) b->data;

	index = frame_index(zone, frame);

	printf("%zd", index);

}				     

/** 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,

	.print_id = zone_buddy_print_id

};

/******************/

/* 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--;

}

/** 

 * Join 2 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 < 0 || z1 >= zones.count || z2 < 0 || 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 frame zone

 *

 * 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;

	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;

	/* 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, int *pzone) 

{

	ipl_t ipl;

	int freed;

	pfn_t v;

	zone_t *zone;

loop:

	ipl = interrupts_disable();

	/*

	 * First, find suitable frame zone.

	 */

	zone = find_free_zone_and_lock(order, 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, pzone);

		if (!zone) {

			freed = slab_reclaim(SLAB_RECLAIM_ALL);

			if (freed)

				zone = find_free_zone_and_lock(order, pzone);

		}

	}

	if (!zone) {

		/*

		 * TODO: Sleep until frames are available again.

		 */

		interrupts_restore(ipl);

		if (flags & FRAME_ATOMIC)

			return 0;

		panic("Sleep not implemented.\n");

		goto loop;

	}

	v = zone_frame_alloc(zone, order);

	v += zone->base;

	spinlock_unlock(&zone->lock);

	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);

	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

 *

 * Initialize physical memory managemnt.

 */

void frame_init(void)

{