text: /*
   * Copyright (c) 1991, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * This code is derived from software contributed to Berkeley by
   * The Mach Operating System project at Carnegie-Mellon University.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. 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.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This product includes software developed by the University of
   *	California, Berkeley and its contributors.
   * 4. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
   *
   *	from: @(#)vm_page.h	8.2 (Berkeley) 12/13/93
   *
   *
   * Copyright (c) 1987, 1990 Carnegie-Mellon University.
   * All rights reserved.
   *
   * Authors: Avadis Tevanian, Jr., Michael Wayne Young
   *
   * Permission to use, copy, modify and distribute this software and
   * its documentation is hereby granted, provided that both the copyright
   * notice and this permission notice appear in all copies of the
   * software, derivative works or modified versions, and any portions
   * thereof, and that both notices appear in supporting documentation.
   *
   * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
   * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
   * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   *
   * Carnegie Mellon requests users of this software to return to
   *
   *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   *  School of Computer Science
   *  Carnegie Mellon University
   *  Pittsburgh PA 15213-3890
   *
   * any improvements or extensions that they make and grant Carnegie the
   * rights to redistribute these changes.
   *
   * $FreeBSD: src/sys/vm/vm_page.h,v 1.75 1999/12/29 04:55:10 peter Exp $
   */
  
  /*
   *	Resident memory system definitions.
   */
  
  #ifndef	_VM_PAGE_
  #define	_VM_PAGE_
  
  #if !defined(KLD_MODULE)
  #include "opt_vmpage.h"
  #endif
  
  #include <vm/pmap.h>
  #include <machine/atomic.h>
  
  /*
   *	Management of resident (logical) pages.
   *
   *	A small structure is kept for each resident
   *	page, indexed by page number.  Each structure
   *	is an element of several lists:
   *
   *		A hash table bucket used to quickly
   *		perform object/offset lookups
   *
   *		A list of all pages for a given object,
   *		so they can be quickly deactivated at
   *		time of deallocation.
   *
   *		An ordered list of pages due for pageout.
   *
   *	In addition, the structure contains the object
   *	and offset to which this page belongs (for pageout),
   *	and sundry status bits.
   *
   *	Fields in this structure are locked either by the lock on the
   *	object that the page belongs to (O) or by the lock on the page
   *	queues (P).
   *
   *	The 'valid' and 'dirty' fields are distinct.  A page may have dirty
   *	bits set without having associated valid bits set.  This is used by
   *	NFS to implement piecemeal writes.
   */
  
  TAILQ_HEAD(pglist, vm_page);
  
  struct vm_page {
  	TAILQ_ENTRY(vm_page) pageq;	/* queue info for FIFO queue or free list (P) */
  	struct vm_page	*hnext;		/* hash table link (O,P)	*/
  	TAILQ_ENTRY(vm_page) listq;	/* pages in same object (O) 	*/
  
  	vm_object_t object;		/* which object am I in (O,P)*/
  	vm_pindex_t pindex;		/* offset into object (O,P) */
  	vm_offset_t phys_addr;		/* physical address of page */
  	u_short	queue;			/* page queue index */
  	u_short	flags,			/* see below */
  		pc;			/* page color */
  	u_short wire_count;		/* wired down maps refs (P) */
  	short hold_count;		/* page hold count */
  	u_char	act_count;		/* page usage count */
  	u_char	busy;			/* page busy count */
  	/* NOTE that these must support one bit per DEV_BSIZE in a page!!! */
  	/* so, on normal X86 kernels, they must be at least 8 bits wide */
  #if PAGE_SIZE == 4096
  	u_char	valid;			/* map of valid DEV_BSIZE chunks */
  	u_char	dirty;			/* map of dirty DEV_BSIZE chunks */
  #elif PAGE_SIZE == 8192
  	u_short	valid;			/* map of valid DEV_BSIZE chunks */
  	u_short	dirty;			/* map of dirty DEV_BSIZE chunks */
  #endif
  };
  
  /*
   * note: currently use SWAPBLK_NONE as an absolute value rather then 
   * a flag bit.
   */
  
  #define SWAPBLK_MASK	((daddr_t)((u_daddr_t)-1 >> 1))		/* mask */
  #define SWAPBLK_NONE	((daddr_t)((u_daddr_t)SWAPBLK_MASK + 1))/* flag */
  
  #if !defined(KLD_MODULE)
  
  /*
   * Page coloring parameters
   */
  /* Each of PQ_FREE, and PQ_CACHE have PQ_HASH_SIZE entries */
  
  /* Define one of the following */
  #if defined(PQ_HUGECACHE)
  #define PQ_PRIME1 31	/* Prime number somewhat less than PQ_HASH_SIZE */
  #define PQ_PRIME2 23	/* Prime number somewhat less than PQ_HASH_SIZE */
  #define PQ_L2_SIZE 256	/* A number of colors opt for 1M cache */
  #endif
  
  /* Define one of the following */
  #if defined(PQ_LARGECACHE)
  #define PQ_PRIME1 31	/* Prime number somewhat less than PQ_HASH_SIZE */
  #define PQ_PRIME2 23	/* Prime number somewhat less than PQ_HASH_SIZE */
  #define PQ_L2_SIZE 128	/* A number of colors opt for 512K cache */
  #endif
  
  
  /*
   * Use 'options PQ_NOOPT' to disable page coloring
   */
  #if defined(PQ_NOOPT)
  #define PQ_PRIME1 1
  #define PQ_PRIME2 1
  #define PQ_L2_SIZE 1
  #endif
  
  #if defined(PQ_NORMALCACHE)
  #define PQ_PRIME1 5	/* Prime number somewhat less than PQ_HASH_SIZE */
  #define PQ_PRIME2 3	/* Prime number somewhat less than PQ_HASH_SIZE */
  #define PQ_L2_SIZE 16	/* A reasonable number of colors (opt for 64K cache) */
  #endif
  
  #if defined(PQ_MEDIUMCACHE)
  #define PQ_PRIME1 13	/* Prime number somewhat less than PQ_HASH_SIZE */
  #define PQ_PRIME2 7	/* Prime number somewhat less than PQ_HASH_SIZE */
  #define PQ_L2_SIZE 64	/* A number of colors opt for 256K cache */
  #endif
  
  #if !defined(PQ_L2_SIZE)
  #define PQ_PRIME1 9	/* Produces a good PQ_L2_SIZE/3 + PQ_PRIME1 */
  #define PQ_PRIME2 5	/* Prime number somewhat less than PQ_HASH_SIZE */
  #define PQ_L2_SIZE 32	/* 512KB or smaller, 4-way set-associative cache */
  #endif
  
  #define PQ_L2_MASK (PQ_L2_SIZE - 1)
  
  #if 1
  #define PQ_NONE 0
  #define PQ_FREE	1
  #define PQ_INACTIVE (1 + 1*PQ_L2_SIZE)
  #define PQ_ACTIVE (2 + 1*PQ_L2_SIZE)
  #define PQ_CACHE (3 + 1*PQ_L2_SIZE)
  #define PQ_COUNT (3 + 2*PQ_L2_SIZE)
  #else
  #define PQ_NONE		PQ_COUNT
  #define PQ_FREE		0
  #define PQ_INACTIVE	PQ_L2_SIZE
  #define PQ_ACTIVE	(1 +   PQ_L2_SIZE)
  #define PQ_CACHE	(2 +   PQ_L2_SIZE)
  #define PQ_COUNT	(2 + 2*PQ_L2_SIZE)
  #endif
  
  struct vpgqueues {
  	struct pglist pl;
  	int	*cnt;
  	int	lcnt;
  };
  
  extern struct vpgqueues vm_page_queues[PQ_COUNT];
  
  #endif
  
  /*
   * These are the flags defined for vm_page.
   *
   * Note: PG_FILLED and PG_DIRTY are added for the filesystems.
   */
  #define	PG_BUSY		0x0001		/* page is in transit (O) */
  #define	PG_WANTED	0x0002		/* someone is waiting for page (O) */
  #define	PG_FICTITIOUS	0x0008		/* physical page doesn't exist (O) */
  #define	PG_WRITEABLE	0x0010		/* page is mapped writeable */
  #define PG_MAPPED	0x0020		/* page is mapped */
  #define	PG_ZERO		0x0040		/* page is zeroed */
  #define PG_REFERENCED	0x0080		/* page has been referenced */
  #define PG_CLEANCHK	0x0100		/* page will be checked for cleaning */
  #define PG_SWAPINPROG	0x0200		/* swap I/O in progress on page	     */
  #define PG_NOSYNC	0x0400		/* do not collect for syncer */
  
  /*
   * Misc constants.
   */
  
  #define ACT_DECLINE		1
  #define ACT_ADVANCE		3
  #define ACT_INIT		5
  #define ACT_MAX			64
  #define PFCLUSTER_BEHIND	3
  #define PFCLUSTER_AHEAD		3
  
  #ifdef _KERNEL
  /*
   * Each pageable resident page falls into one of four lists:
   *
   *	free
   *		Available for allocation now.
   *
   * The following are all LRU sorted:
   *
   *	cache
   *		Almost available for allocation. Still in an
   *		object, but clean and immediately freeable at
   *		non-interrupt times.
   *
   *	inactive
   *		Low activity, candidates for reclamation.
   *		This is the list of pages that should be
   *		paged out next.
   *
   *	active
   *		Pages that are "active" i.e. they have been
   *		recently referenced.
   *
   *	zero
   *		Pages that are really free and have been pre-zeroed
   *
   */
  
  extern int vm_page_zero_count;
  
  extern vm_page_t vm_page_array;		/* First resident page in table */
  extern long first_page;			/* first physical page number */
  
  #define VM_PAGE_TO_PHYS(entry)	((entry)->phys_addr)
  
  #define PHYS_TO_VM_PAGE(pa) \
  		(&vm_page_array[atop(pa) - first_page ])
  
  /*
   *	Functions implemented as macros
   */
  
  static __inline void
  vm_page_flag_set(vm_page_t m, unsigned int bits)
  {
  	atomic_set_short(&(m)->flags, bits);
  }
  
  static __inline void
  vm_page_flag_clear(vm_page_t m, unsigned int bits)
  {
  	atomic_clear_short(&(m)->flags, bits);
  }
  
  #if 0
  static __inline void
  vm_page_assert_wait(vm_page_t m, int interruptible)
  {
  	vm_page_flag_set(m, PG_WANTED);
  	assert_wait((int) m, interruptible);
  }
  #endif
  
  static __inline void
  vm_page_busy(vm_page_t m)
  {
  	KASSERT((m->flags & PG_BUSY) == 0, ("vm_page_busy: page already busy!!!"));
  	vm_page_flag_set(m, PG_BUSY);
  }
  
  /*
   *	vm_page_flash:
   *
   *	wakeup anyone waiting for the page.
   */
  
  static __inline void
  vm_page_flash(vm_page_t m)
  {
  	if (m->flags & PG_WANTED) {
  		vm_page_flag_clear(m, PG_WANTED);
  		wakeup(m);
  	}
  }
  
  /*
   *	vm_page_wakeup:
   *
   *	clear the PG_BUSY flag and wakeup anyone waiting for the
   *	page.
   *
   */
  
  static __inline void
  vm_page_wakeup(vm_page_t m)
  {
  	KASSERT(m->flags & PG_BUSY, ("vm_page_wakeup: page not busy!!!"));
  	vm_page_flag_clear(m, PG_BUSY);
  	vm_page_flash(m);
  }
  
  /*
   *
   *
   */
  
  static __inline void
  vm_page_io_start(vm_page_t m)
  {
  	atomic_add_char(&(m)->busy, 1);
  }
  
  static __inline void
  vm_page_io_finish(vm_page_t m)
  {
  	atomic_subtract_char(&m->busy, 1);
  	if (m->busy == 0)
  		vm_page_flash(m);
  }
  
  
  #if PAGE_SIZE == 4096
  #define VM_PAGE_BITS_ALL 0xff
  #endif
  
  #if PAGE_SIZE == 8192
  #define VM_PAGE_BITS_ALL 0xffff
  #endif
  
  #define VM_ALLOC_NORMAL		0
  #define VM_ALLOC_INTERRUPT	1
  #define VM_ALLOC_SYSTEM		2
  #define	VM_ALLOC_ZERO		3
  #define	VM_ALLOC_RETRY		0x80
  
  void vm_page_activate __P((vm_page_t));
  vm_page_t vm_page_alloc __P((vm_object_t, vm_pindex_t, int));
  vm_page_t vm_page_grab __P((vm_object_t, vm_pindex_t, int));
  void vm_page_cache __P((register vm_page_t));
  void vm_page_dontneed __P((register vm_page_t));
  static __inline void vm_page_copy __P((vm_page_t, vm_page_t));
  static __inline void vm_page_free __P((vm_page_t));
  static __inline void vm_page_free_zero __P((vm_page_t));
  void vm_page_deactivate __P((vm_page_t));
  void vm_page_insert __P((vm_page_t, vm_object_t, vm_pindex_t));
  vm_page_t vm_page_lookup __P((vm_object_t, vm_pindex_t));
  void vm_page_remove __P((vm_page_t));
  void vm_page_rename __P((vm_page_t, vm_object_t, vm_pindex_t));
  vm_offset_t vm_page_startup __P((vm_offset_t, vm_offset_t, vm_offset_t));
  void vm_page_unwire __P((vm_page_t, int));
  void vm_page_wire __P((vm_page_t));
  void vm_page_unqueue __P((vm_page_t));
  void vm_page_unqueue_nowakeup __P((vm_page_t));
  void vm_page_set_validclean __P((vm_page_t, int, int));
  void vm_page_set_dirty __P((vm_page_t, int, int));
  void vm_page_clear_dirty __P((vm_page_t, int, int));
  void vm_page_set_invalid __P((vm_page_t, int, int));
  static __inline boolean_t vm_page_zero_fill __P((vm_page_t));
  int vm_page_is_valid __P((vm_page_t, int, int));
  void vm_page_test_dirty __P((vm_page_t));
  int vm_page_bits __P((int, int));
  vm_page_t _vm_page_list_find __P((int, int));
  #if 0
  int vm_page_sleep(vm_page_t m, char *msg, char *busy);
  int vm_page_asleep(vm_page_t m, char *msg, char *busy);
  #endif
  void vm_page_zero_invalid(vm_page_t m, boolean_t setvalid);
  void vm_page_free_toq(vm_page_t m);
  
  /*
   * Keep page from being freed by the page daemon
   * much of the same effect as wiring, except much lower
   * overhead and should be used only for *very* temporary
   * holding ("wiring").
   */
  static __inline void
  vm_page_hold(vm_page_t mem)
  {
  	mem->hold_count++;
  }
  
  static __inline void
  vm_page_unhold(vm_page_t mem)
  {
  	--mem->hold_count;
  	KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!"));
  }
  
  /*
   * 	vm_page_protect:
   *
   *	Reduce the protection of a page.  This routine never raises the 
   *	protection and therefore can be safely called if the page is already
   *	at VM_PROT_NONE (it will be a NOP effectively ).
   */
  
  static __inline void
  vm_page_protect(vm_page_t mem, int prot)
  {
  	if (prot == VM_PROT_NONE) {
  		if (mem->flags & (PG_WRITEABLE|PG_MAPPED)) {
  			pmap_page_protect(VM_PAGE_TO_PHYS(mem), VM_PROT_NONE);
  			vm_page_flag_clear(mem, PG_WRITEABLE|PG_MAPPED);
  		}
  	} else if ((prot == VM_PROT_READ) && (mem->flags & PG_WRITEABLE)) {
  		pmap_page_protect(VM_PAGE_TO_PHYS(mem), VM_PROT_READ);
  		vm_page_flag_clear(mem, PG_WRITEABLE);
  	}
  }
  
  /*
   *	vm_page_zero_fill:
   *
   *	Zero-fill the specified page.
   *	Written as a standard pagein routine, to
   *	be used by the zero-fill object.
   */
  static __inline boolean_t
  vm_page_zero_fill(m)
  	vm_page_t m;
  {
  	pmap_zero_page(VM_PAGE_TO_PHYS(m));
  	return (TRUE);
  }
  
  /*
   *	vm_page_copy:
   *
   *	Copy one page to another
   */
  static __inline void
  vm_page_copy(src_m, dest_m)
  	vm_page_t src_m;
  	vm_page_t dest_m;
  {
  	pmap_copy_page(VM_PAGE_TO_PHYS(src_m), VM_PAGE_TO_PHYS(dest_m));
  	dest_m->valid = VM_PAGE_BITS_ALL;
  }
  
  /*
   *	vm_page_free:
   *
   *	Free a page
   *
   *	The clearing of PG_ZERO is a temporary safety until the code can be
   *	reviewed to determine that PG_ZERO is being properly cleared on
   *	write faults or maps.  PG_ZERO was previously cleared in 
   *	vm_page_alloc().
   */
  static __inline void
  vm_page_free(m)
  	vm_page_t m;
  {
  	vm_page_flag_clear(m, PG_ZERO);
  	vm_page_free_toq(m);
  }
  
  /*
   *	vm_page_free_zero:
   *
   *	Free a page to the zerod-pages queue
   */
  static __inline void
  vm_page_free_zero(m)
  	vm_page_t m;
  {
  	vm_page_flag_set(m, PG_ZERO);
  	vm_page_free_toq(m);
  }
  
  /*
   *	vm_page_sleep_busy:
   *
   *	Wait until page is no longer PG_BUSY or (if also_m_busy is TRUE)
   *	m->busy is zero.  Returns TRUE if it had to sleep ( including if 
   *	it almost had to sleep and made temporary spl*() mods), FALSE 
   *	otherwise.
   *
   *	This routine assumes that interrupts can only remove the busy
   *	status from a page, not set the busy status or change it from
   *	PG_BUSY to m->busy or vise versa (which would create a timing
   *	window).
   *
   *	Note that being an inline, this code will be well optimized.
   */
  
  static __inline int
  vm_page_sleep_busy(vm_page_t m, int also_m_busy, const char *msg)
  {
  	if ((m->flags & PG_BUSY) || (also_m_busy && m->busy))  {
  		int s = splvm();
  		if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) {
  			/*
  			 * Page is busy. Wait and retry.
  			 */
  			vm_page_flag_set(m, PG_WANTED | PG_REFERENCED);
  			tsleep(m, PVM, msg, 0);
  		}
  		splx(s);
  		return(TRUE);
  		/* not reached */
  	}
  	return(FALSE);
  }
  
  /*
   *	vm_page_dirty:
   *
   *	make page all dirty
   */
  
  static __inline void
  vm_page_dirty(vm_page_t m)
  {
  #if !defined(KLD_MODULE)
  	KASSERT(m->queue - m->pc != PQ_CACHE, ("vm_page_dirty: page in cache!"));
  #endif
  	m->dirty = VM_PAGE_BITS_ALL;
  }
  
  /*
   *	vm_page_undirty:
   *
   *	Set page to not be dirty.  Note: does not clear pmap modify bits 
   */
  
  static __inline void
  vm_page_undirty(vm_page_t m)
  {
  	m->dirty = 0;
  }
  
  #if !defined(KLD_MODULE)
  
  static __inline vm_page_t
  vm_page_list_find(int basequeue, int index, boolean_t prefer_zero)
  {
  	vm_page_t m;
  
  #if PQ_L2_SIZE > 1
  	if (prefer_zero) {
  		m = TAILQ_LAST(&vm_page_queues[basequeue+index].pl, pglist);
  	} else {
  		m = TAILQ_FIRST(&vm_page_queues[basequeue+index].pl);
  	}
  	if (m == NULL)
  		m = _vm_page_list_find(basequeue, index);
  #else
  	if (prefer_zero) {
  		m = TAILQ_LAST(&vm_page_queues[basequeue].pl, pglist);
  	} else {
  		m = TAILQ_FIRST(&vm_page_queues[basequeue].pl);
  	}
  #endif
  	return(m);
  }
  
  #endif
  
  #endif				/* _KERNEL */
  #endif				/* !_VM_PAGE_ */
  