/*
 * page.c - physical page related operations implementation
 *
 * Authors  Ghassan Almaless (2008,2009,2010,2011,2012)
 *          Alain Greiner    (2016,2017)
 *
 * Copyright (c) UPMC Sorbonne Universites
 *
 * This file is part of ALMOS-MKH.
 *
 * ALMOS-MKH is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2.0 of the License.
 *
 * ALMOS-MKH is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <hal_kernel_types.h>
#include <hal_special.h>
#include <hal_atomic.h>
#include <list.h>
#include <xlist.h>
#include <memcpy.h>
#include <thread.h>
#include <scheduler.h>
#include <cluster.h>
#include <ppm.h>
#include <mapper.h>
#include <printk.h>
#include <vfs.h>
#include <process.h>
#include <page.h>

////////////////////////////////////////
inline void page_init( page_t   * page )
{
	page->flags    = 0;
	page->order    = 0;
	page->mapper   = NULL;
	page->index    = 0;
	page->refcount = 0;
	page->forks    = 0;

	spinlock_init( &page->lock );
	list_entry_init( &page->list );
    xlist_root_init( XPTR( local_cxy , &page->wait_root ) );
}

////////////////////////////////////////////
inline void page_set_flag( page_t   * page,
                           uint32_t   value )
{
	hal_atomic_or( (uint32_t *)&page->flags , (uint32_t)value );
}

//////////////////////////////////////////////
inline void page_clear_flag( page_t   * page,
                             uint32_t   value )
{
	hal_atomic_and( (uint32_t *)&page->flags , ~((uint32_t)value) );
}

//////////////////////////////////////////////
inline bool_t page_is_flag( page_t   * page,
                            uint32_t   value )
{
    return ( (page->flags & value) ? 1 : 0 );
}

//////////////////////////////////////
bool_t page_do_dirty( page_t * page )
{
	bool_t done = false;

	ppm_t * ppm = &LOCAL_CLUSTER->ppm;

	// lock the PPM dirty_list
	spinlock_lock( &ppm->dirty_lock );

	if( !page_is_flag( page , PG_DIRTY ) )
	{
		// set dirty flag in page descriptor
		page_set_flag( page , PG_DIRTY );

		// register page in PPM dirty list
		list_add_first( &ppm->dirty_root , &page->list );
		done = true;
	}

	// unlock the PPM dirty_list
	spinlock_unlock( &ppm->dirty_lock );

	return done;
}

////////////////////////////////////////
bool_t page_undo_dirty( page_t * page )
{
	bool_t done = false;

	ppm_t * ppm = &LOCAL_CLUSTER->ppm;

	// lock the dirty_list
	spinlock_lock( &ppm->dirty_lock );

	if( page_is_flag( page , PG_DIRTY) )
	{
		// clear dirty flag in page descriptor
		page_clear_flag( page , PG_DIRTY );

		// remove page from PPM dirty list
		list_unlink( &page->list );
		done = true;
	}

	// unlock the dirty_list
	spinlock_unlock( &ppm->dirty_lock );

	return done;
}

/////////////////////
void sync_all_pages( void )
{
	page_t   * page;
	ppm_t    * ppm = &LOCAL_CLUSTER->ppm;

	// lock the dirty_list
	spinlock_lock( &ppm->dirty_lock );

	while( !list_is_empty( &ppm->dirty_root ) )
	{
		page = LIST_FIRST( &ppm->dirty_root ,  page_t , list );

		// unlock the dirty_list
		spinlock_unlock( &ppm->dirty_lock );

		// lock the page
		page_lock( page );

		// sync the page
		vfs_mapper_move_page( page , false );  // from mapper

		// unlock the page
		page_unlock( page );

		// lock the dirty_list
		spinlock_lock( &ppm->dirty_lock );
	}

	// unlock the dirty_list
	spinlock_unlock( &ppm->dirty_lock );

}

///////////////////////////////
void page_lock( page_t * page )
{
	// take the spinlock protecting the PG_LOCKED flag
	spinlock_lock( &page->lock );

	if( page_is_flag( page , PG_LOCKED ) )  // page is already locked
	{
		// get pointer on calling thread
		thread_t * thread = CURRENT_THREAD;

		// register thread in the page waiting queue
		xlist_add_last( XPTR( local_cxy , &page->wait_root ),
		                XPTR( local_cxy , &thread->wait_list ) );

		// release the spinlock
		spinlock_unlock( &page->lock );

		// deschedule the calling thread
		thread_block( XPTR( local_cxy , thread ) , THREAD_BLOCKED_PAGE );
		sched_yield("cannot lock a page");
	}
	else                                    // page is not locked
	{
		// set the PG_LOCKED flag
		page_set_flag( page , PG_LOCKED );

		// release the spinlock
		spinlock_unlock( &page->lock );
	}
}

/////////////////////////////////
void page_unlock( page_t * page )
{
	// take the spinlock protecting the PG_LOCKED flag
	spinlock_lock( &page->lock );

	// check the page waiting list
	bool_t is_empty = xlist_is_empty( XPTR( local_cxy , &page->wait_root ) );

	if( is_empty == false )    // at least one waiting thread => resume it
	{
		// get an extended pointer on the first waiting thread
		xptr_t root_xp   = XPTR( local_cxy , &page->wait_root );
		xptr_t thread_xp = XLIST_FIRST_ELEMENT( root_xp , thread_t , wait_list );

		// reactivate the first waiting thread
		thread_unblock( thread_xp , THREAD_BLOCKED_PAGE );
	}
	else                      // no waiting thread => clear the PG_LOCKED flag
	{
		page_clear_flag( page , PG_LOCKED );
	}

	// release the spinlock
	spinlock_unlock( &page->lock );
}

////////////////////////////////////////////
inline void page_refcount_up( page_t *page )
{
    hal_atomic_add( &page->refcount , +1 );
}

//////////////////////////////////////////////
inline void page_refcount_down( page_t *page )
{
    hal_atomic_add( &page->refcount , -1 );
}

///////////////////////////////
void page_zero( page_t * page )
{
	uint32_t   size = (1 << page->order) * CONFIG_PPM_PAGE_SIZE;

	xptr_t base_xp = ppm_page2base( XPTR( local_cxy , page ) );

	memset( GET_PTR( base_xp ) , 0 , size );
}

////////////////////////////////
void page_print( page_t * page )
{
	printk("*** Page %d : base = %x / flags = %x / order = %d / count = %d\n",
	        page->index,
	        GET_PTR( ppm_page2base( XPTR( local_cxy , page ) ) ),
	        page->flags,
	        page->order,
	        page->refcount );
}

