xref: /src/sys/uvm/uvm_page.h

/*	$NetBSD: uvm_page.h,v 1.73.2.11 2012/05/23 10:08:20 yamt Exp $	*/

/*
 * Copyright (c) 1997 Charles D. Cranor and Washington University.
 * 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. 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.
 *
 *	@(#)vm_page.h   7.3 (Berkeley) 4/21/91
 * from: Id: uvm_page.h,v 1.1.2.6 1998/02/04 02:31:42 chuck Exp
 *
 *
 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
 * All rights reserved.
 *
 * 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 (at) 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.
 */

#ifndef _UVM_UVM_PAGE_H_
#define _UVM_UVM_PAGE_H_

#include <uvm/uvm_extern.h>
#include <uvm/uvm_pglist.h>

/*
 * Management of resident (logical) pages.
 *
 * Each resident page has a vm_page structure, indexed by page number.
 * There are several lists in the structure:
 *
 * - A radix tree rooted with the containing object is used to
 *   quickly perform object+offset lookups.
 * - 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.
 *
 * Note that the page structure has no lock of its own.  The page is
 * generally protected by its owner's lock (UVM object or amap/anon).
 * It should be noted that UVM has to serialize pmap(9) operations on
 * the managed pages, e.g. for pmap_enter() calls.  Hence, the lock
 * order is as follows:
 *
 *	[vmpage-owner-lock] ->
 *		any pmap locks (e.g. PV hash lock)
 *
 * Since the kernel is always self-consistent, no serialization is
 * required for unmanaged mappings, e.g. for pmap_kenter_pa() calls.
 *
 * Field markings and the corresponding locks:
 *
 * o:	page owner's lock (UVM object or amap/anon)
 * p:	lock on the page queues
 * o|p:	either lock can be acquired
 * o&p:	both locks are required
 * ?:	locked by pmap or assumed page owner's lock
 *
 * UVM and pmap(9) may use uvm_page_locked_p() to assert whether the
 * page owner's lock is acquired.
 */

struct vm_page {
	union {
		TAILQ_ENTRY(vm_page) queue;
		LIST_ENTRY(vm_page) list;
	} pageq;				/* p: queue info for FIFO
						 * queue or free list */

	union {
		struct {
			struct vm_anon *o_anon;	/* o,p: anon */
			struct uvm_object *o_object; /* o,p: object */
		} owner;
#define uanon	u.owner.o_anon
#define	uobject	u.owner.o_object
		LIST_ENTRY(vm_page) cpulist;
	} u;
	voff_t			offset;		/* o,p: offset into object */
	uint16_t		flags;		/* o: object flags */
	uint16_t		loan_count;	/* number of active loans
						 * o|p: for reading
						 * o&p: for modification */
	uint16_t		wire_count;	/* p: wired down map refs */
	uint16_t		pqflags;	/* p: page queue flags */
	paddr_t			phys_addr;	/* physical address of page */

#ifdef __HAVE_VM_PAGE_MD
	struct vm_page_md	mdpage;		/* ?: pmap-specific data */
#endif

#if defined(UVM_PAGE_TRKOWN)
	/* debugging fields to track page ownership */
	pid_t			owner;		/* proc that set PG_BUSY */
	lwpid_t			lowner;		/* lwp that set PG_BUSY */
	const char		*owner_tag;	/* why it was set busy */
#endif
};

/*
 * Overview of UVM page flags.
 *
 * Locking notes:
 *
 * PG_, struct vm_page::flags	=> locked by the owner
 * PQ_, struct vm_page::pqflags	=> locked by the page-queue lock
 * PQ_FREE			=> additionally locked by free-queue lock
 *
 * Flag descriptions:
 *
 * PG_CLEAN:
 *	Page is known clean.
 *	The contents of the page is consistent with its backing store.
 *
 * PG_DIRTY:
 *	Page is known dirty.
 *	To avoid losing data, the contents of the page should be written
 *	back to the backing store before freeing the page.
 *
 * PG_BUSY:
 *	Page is long-term locked, usually because of I/O (transfer from the
 *	page memory to the backing store) is in progress.  LWP attempting
 *	to access the page shall set PG_WANTED and wait.
 *
 * PG_WANTED:
 *	Indicates that the page, which is currently PG_BUSY, is wanted by
 *	some other LWP.  The page owner (i.e. LWP which set PG_BUSY) is
 *	responsible to clear both flags and wake up any waiters once it has
 *	released the long-term lock (PG_BUSY).
 *
 * PG_PAGEOUT:
 *	Indicates that the page is being paged-out in preparation for
 *	being freed.
 *
 * PG_RELEASED:
 *	Indicates that the page, which is currently PG_BUSY, should be freed
 *	after the release of long-term lock.  It is responsibility of the
 *	owning LWP (i.e. which set PG_BUSY) to do it.
 *
 * PG_FAKE:
 *	Page has been allocated, but not yet initialised.  The flag is used
 *	to avoid overwriting of valid data, e.g. to prevent read from the
 *	backing store when in-core data is newer.
 *
 * PG_RDONLY:
 *	Indicates that the page must be mapped read-only.
 *
 * PG_ZERO:
 *	Indicates that the page has been pre-zeroed.  This flag is only
 *	set when the page is not in the queues and is cleared when the
 *	page is placed on the free list.
 *
 * PG_TABLED:
 *	Indicates that the page is currently in the object's offset queue,
 *	and that it should be removed from it once the page is freed.  Used
 *	diagnostic purposes.
 */

/*
 * if you want to renumber PG_CLEAN and PG_DIRTY, check __CTASSERTs in
 * uvm_page_status.c first.
 */

#define	PG_CLEAN	0x0001		/* page is known clean */
#define	PG_DIRTY	0x0002		/* page is known dirty */
#define	PG_BUSY		0x0004		/* page is locked */
#define	PG_WANTED	0x0008		/* someone is waiting for page */
#define	PG_PAGEOUT	0x0010		/* page to be freed for pagedaemon */
#define PG_RELEASED	0x0020		/* page to be freed when unbusied */
#define	PG_FAKE		0x0040		/* page is not yet initialized */
#define	PG_RDONLY	0x0080		/* page must be mapped read-only */
#define	PG_ZERO		0x0100		/* page is pre-zero'd */
#define	PG_TABLED	0x0200		/* page is in VP table  */

#define PG_PAGER1	0x1000		/* pager-specific flag */
#define PG_PAGER2	0x2000		/* pager-specific flag */

#define	UVM_PGFLAGBITS \
	"\20\1CLEAN\2DIRTY\3BUSY\4WANTED" \
	"\5PAGEOUT\6RELEASED\7FAKE\10RDONLY" \
	"\11ZERO\12TABLED" \
	"\15PAGER1\16PAGER2"

#define PQ_FREE		0x0001		/* page is on free list */
#define PQ_ANON		0x0002		/* page is part of an anon, rather
					   than an uvm_object */
#define PQ_AOBJ		0x0004		/* page is part of an anonymous
					   uvm_object */
#define PQ_SWAPBACKED	(PQ_ANON|PQ_AOBJ)
#define PQ_READAHEAD	0x0008	/* read-ahead but has not been "hit" yet */
#define	PQ_FILE		0x0010		/* file backed (non-anonymous) */
#define	PQ_STAT		(PQ_ANON|PQ_AOBJ|PQ_FILE)

#define PQ_PRIVATE1	0x0100
#define PQ_PRIVATE2	0x0200
#define PQ_PRIVATE3	0x0400
#define PQ_PRIVATE4	0x0800
#define PQ_PRIVATE5	0x1000
#define PQ_PRIVATE6	0x2000
#define PQ_PRIVATE7	0x4000
#define PQ_PRIVATE8	0x8000

#define	UVM_PQFLAGBITS \
	"\20\1FREE\2ANON\3AOBJ\4READAHEAD\5FILE" \
	"\11PRIVATE1\12PRIVATE2\13PRIVATE3\14PRIVATE4" \
	"\15PRIVATE5\16PRIVATE6\17PRIVATE7\20PRIVATE8"

/*
 * physical memory layout structure
 *
 * MD vmparam.h must #define:
 *   VM_PHYSEG_MAX = max number of physical memory segments we support
 *		   (if this is "1" then we revert to a "contig" case)
 *   VM_PHYSSEG_STRAT: memory sort/search options (for VM_PHYSEG_MAX > 1)
 * 	- VM_PSTRAT_RANDOM:   linear search (random order)
 *	- VM_PSTRAT_BSEARCH:  binary search (sorted by address)
 *	- VM_PSTRAT_BIGFIRST: linear search (sorted by largest segment first)
 *      - others?
 *   XXXCDC: eventually we should purge all left-over global variables...
 */
#define VM_PSTRAT_RANDOM	1
#define VM_PSTRAT_BSEARCH	2
#define VM_PSTRAT_BIGFIRST	3

/*
 * vm_physseg: describes one segment of physical memory
 */
struct vm_physseg {
	paddr_t	start;			/* PF# of first page in segment */
	paddr_t	end;			/* (PF# of last page in segment) + 1 */
	paddr_t	avail_start;		/* PF# of first free page in segment */
	paddr_t	avail_end;		/* (PF# of last free page in segment) +1  */
	struct	vm_page *pgs;		/* vm_page structures (from start) */
	struct	vm_page *lastpg;	/* vm_page structure for end */
	int	free_list;		/* which free list they belong on */
	u_int	start_hint;		/* start looking for free pages here */
					/* protected by uvm_fpageqlock */
#ifdef __HAVE_PMAP_PHYSSEG
	struct	pmap_physseg pmseg;	/* pmap specific (MD) data */
#endif
};

#ifdef _KERNEL

/*
 * globals
 */

extern bool vm_page_zero_enable;

/*
 * physical memory config is stored in vm_physmem.
 */

#define	VM_PHYSMEM_PTR(i)	(&vm_physmem[i])
#define VM_PHYSMEM_PTR_SWAP(i, j) \
	do { vm_physmem[(i)] = vm_physmem[(j)]; } while (0)

extern struct vm_physseg vm_physmem[VM_PHYSSEG_MAX];
extern int vm_nphysseg;

/*
 * prototypes: the following prototypes define the interface to pages
 */

void uvm_page_init(vaddr_t *, vaddr_t *);
#if defined(UVM_PAGE_TRKOWN)
void uvm_page_own(struct vm_page *, const char *);
#endif
#if !defined(PMAP_STEAL_MEMORY)
bool uvm_page_physget(paddr_t *);
#endif
void uvm_page_recolor(int);
void uvm_pageidlezero(void);

void uvm_pageactivate(struct vm_page *);
vaddr_t uvm_pageboot_alloc(vsize_t);
void uvm_pagecopy(struct vm_page *, struct vm_page *);
void uvm_pagedeactivate(struct vm_page *);
void uvm_pagedequeue(struct vm_page *);
void uvm_pageenqueue(struct vm_page *);
void uvm_pagefree(struct vm_page *);
void uvm_page_unbusy(struct vm_page **, int);
struct vm_page *uvm_pagelookup(struct uvm_object *, voff_t);
void uvm_pageunwire(struct vm_page *);
void uvm_pagewire(struct vm_page *);
void uvm_pagezero(struct vm_page *);
bool uvm_pageismanaged(paddr_t);
unsigned int uvm_pagegetdirty(struct vm_page *);
void uvm_pagemarkdirty(struct vm_page *, unsigned int);
bool uvm_pagecheckdirty(struct vm_page *, bool);
bool uvm_pagereadonly_p(struct vm_page *);
bool uvm_page_locked_p(struct vm_page *);
kmutex_t *uvm_page_getlock(struct vm_page *);
bool uvm_page_samelock_p(struct vm_page *, struct vm_page *);

struct uvm_cpu;
struct uvm_cpu *uvm_cpu_get(void);
void uvm_cpu_put(struct uvm_cpu *);

/*
 * page dirtiness status for uvm_pagegetdirty and uvm_pagemarkdirty
 *
 * UNKNOWN means that we need to consult pmap to know if the page is
 * dirty or not.
 * basically, UVM_PAGE_STATUS_CLEAN implies that the page has no writable
 * mapping.
 *
 * if you want to renumber these, check __CTASSERTs in
 * uvm_page_status.c first.
 */
#define	UVM_PAGE_STATUS_UNKNOWN	0
#define	UVM_PAGE_STATUS_CLEAN	1
#define	UVM_PAGE_STATUS_DIRTY	2
#define	UVM_PAGE_NUM_STATUS	3

int uvm_page_lookup_freelist(struct vm_page *);

int vm_physseg_find(paddr_t, int *);
struct vm_page *uvm_phys_to_vm_page(paddr_t);
paddr_t uvm_vm_page_to_phys(const struct vm_page *);

/*
 * macros
 */

#define VM_PAGE_TO_PHYS(entry)	uvm_vm_page_to_phys(entry)

#ifdef __HAVE_VM_PAGE_MD
#define	VM_PAGE_TO_MD(pg)	(&(pg)->mdpage)
#endif

/*
 * Compute the page color bucket for a given page.
 */
#define	VM_PGCOLOR_BUCKET(pg) \
	(atop(VM_PAGE_TO_PHYS((pg))) & uvmexp.colormask)

#define	PHYS_TO_VM_PAGE(pa)	uvm_phys_to_vm_page(pa)

#define VM_PAGE_IS_FREE(entry)  ((entry)->pqflags & PQ_FREE)
#define	VM_FREE_PAGE_TO_CPU(pg)	((struct uvm_cpu *)((uintptr_t)pg->offset))

#ifdef DEBUG
void uvm_pagezerocheck(struct vm_page *);
#endif /* DEBUG */

#endif /* _KERNEL */

#endif /* _UVM_UVM_PAGE_H_ */