pmap.h

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/*	$NetBSD: pmap.h,v 1.51 2000/12/06 03:13:47 chs Exp $	*/

/*
 *
 * Copyright (c) 1997 Charles D. Cranor and Washington University.
 * All rights reserved.
 *
 * 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 acknowledgment:
 *      This product includes software developed by Charles D. Cranor and
 *      Washington University.
 * 4. 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.
 */

/*
 * pmap.h: see pmap.c for the history of this pmap module.
 */

#ifndef	_I386_PMAP_H_
#define	_I386_PMAP_H_

#if defined(_KERNEL) && !defined(_LKM)
#include "opt_user_ldt.h"
#include "opt_largepages.h"
#endif

#include <machine/cpufunc.h>
#include <machine/pte.h>
#include <machine/segments.h>
#include <uvm/uvm_object.h>

/*
 * see pte.h for a description of i386 MMU terminology and hardware
 * interface.
 *
 * a pmap describes a processes' 4GB virtual address space.  this
 * virtual address space can be broken up into 1024 4MB regions which
 * are described by PDEs in the PDP.  the PDEs are defined as follows:
 *
 * (ranges are inclusive -> exclusive, just like vm_map_entry start/end)
 * (the following assumes that KERNBASE is 0xc0000000)
 *
 * PDE#s	VA range		usage
 * 0->767	0x0 -> 0xbfc00000	user address space, note that the
 *					max user address is 0xbfbfe000
 *					the final two pages in the last 4MB
 *					used to be reserved for the UAREA
 *					but now are no longer used
 * 768		0xbfc00000->		recursive mapping of PDP (used for
 *			0xc0000000	linear mapping of PTPs)
 * 768->1023	0xc0000000->		kernel address space (constant
 *			0xffc00000	across all pmap's/processes)
 * 1023		0xffc00000->		"alternate" recursive PDP mapping
 *			<end>		(for other pmaps)
 *
 *
 * note: a recursive PDP mapping provides a way to map all the PTEs for
 * a 4GB address space into a linear chunk of virtual memory.  in other
 * words, the PTE for page 0 is the first int mapped into the 4MB recursive
 * area.  the PTE for page 1 is the second int.  the very last int in the
 * 4MB range is the PTE that maps VA 0xffffe000 (the last page in a 4GB
 * address).
 *
 * all pmap's PD's must have the same values in slots 768->1023 so that
 * the kernel is always mapped in every process.  these values are loaded
 * into the PD at pmap creation time.
 *
 * at any one time only one pmap can be active on a processor.  this is
 * the pmap whose PDP is pointed to by processor register %cr3.  this pmap
 * will have all its PTEs mapped into memory at the recursive mapping
 * point (slot #767 as show above).  when the pmap code wants to find the
 * PTE for a virtual address, all it has to do is the following:
 *
 * address of PTE = (767 * 4MB) + (VA / NBPG) * sizeof(pt_entry_t)
 *                = 0xbfc00000 + (VA / 4096) * 4
 *
 * what happens if the pmap layer is asked to perform an operation
 * on a pmap that is not the one which is currently active?  in that
 * case we take the PA of the PDP of non-active pmap and put it in
 * slot 1023 of the active pmap.  this causes the non-active pmap's
 * PTEs to get mapped in the final 4MB of the 4GB address space
 * (e.g. starting at 0xffc00000).
 *
 * the following figure shows the effects of the recursive PDP mapping:
 *
 *   PDP (%cr3)
 *   +----+
 *   |   0| -> PTP#0 that maps VA 0x0 -> 0x400000
 *   |    |
 *   |    |
 *   | 767| -> points back to PDP (%cr3) mapping VA 0xbfc00000 -> 0xc0000000
 *   | 768| -> first kernel PTP (maps 0xc0000000 -> 0xf0400000)
 *   |    |
 *   |1023| -> points to alternate pmap's PDP (maps 0xffc00000 -> end)
 *   +----+
 *
 * note that the PDE#767 VA (0xbfc00000) is defined as "PTE_BASE"
 * note that the PDE#1023 VA (0xffc00000) is defined as "APTE_BASE"
 *
 * starting at VA 0xbfc00000 the current active PDP (%cr3) acts as a
 * PTP:
 *
 * PTP#767 == PDP(%cr3) => maps VA 0xbfc00000 -> 0xc0000000
 *   +----+
 *   |   0| -> maps the contents of PTP#0 at VA 0xbfc00000->0xbfc01000
 *   |    |
 *   |    |
 *   | 767| -> maps contents of PTP#767 (the PDP) at VA 0xbffbf000
 *   | 768| -> maps contents of first kernel PTP
 *   |    |
 *   |1023|
 *   +----+
 *
 * note that mapping of the PDP at PTP#959's VA (0xeffbf000) is
 * defined as "PDP_BASE".... within that mapping there are two
 * defines:
 *   "PDP_PDE" (0xeffbfefc) is the VA of the PDE in the PDP
 *      which points back to itself.
 *   "APDP_PDE" (0xeffbfffc) is the VA of the PDE in the PDP which
 *      establishes the recursive mapping of the alternate pmap.
 *      to set the alternate PDP, one just has to put the correct
 *	PA info in *APDP_PDE.
 *
 * note that in the APTE_BASE space, the APDP appears at VA
 * "APDP_BASE" (0xfffff000).
 */

/*
 * the following defines identify the slots used as described above.
 */

#ifdef OSKIT
#define PDSLOT_PTE	((USERBASE/NBPD)-2)	/* for recursive PDP map */
#define PDSLOT_KERN	(KERNBASE/NBPD)		/* start of kernel space */
#define PDSLOT_APTE	((USERBASE/NBPD)-1)     /* alternative recursive slot */
#else
#define PDSLOT_PTE	((KERNBASE/NBPD)-1) /* 767: for recursive PDP map */
#define PDSLOT_KERN	(KERNBASE/NBPD)	    /* 768: start of kernel space */
#define PDSLOT_APTE	((unsigned)1023) /* 1023: alternative recursive slot */
#endif

/*
 * the following defines give the virtual addresses of various MMU
 * data structures:
 * PTE_BASE and APTE_BASE: the base VA of the linear PTE mappings
 * PTD_BASE and APTD_BASE: the base VA of the recursive mapping of the PTD
 * PDP_PDE and APDP_PDE: the VA of the PDE that points back to the PDP/APDP
 */

#define PTE_BASE	((pt_entry_t *)  (PDSLOT_PTE * NBPD) )
#define APTE_BASE	((pt_entry_t *)  (PDSLOT_APTE * NBPD) )
#define PDP_BASE ((pd_entry_t *)(((char *)PTE_BASE) + (PDSLOT_PTE * NBPG)))
#define APDP_BASE ((pd_entry_t *)(((char *)APTE_BASE) + (PDSLOT_APTE * NBPG)))
#define PDP_PDE		(PDP_BASE + PDSLOT_PTE)
#define APDP_PDE	(PDP_BASE + PDSLOT_APTE)

/*
 * XXXCDC: tmp xlate from old names:
 * PTDPTDI -> PDSLOT_PTE
 * KPTDI -> PDSLOT_KERN
 * APTDPTDI -> PDSLOT_APTE
 */

/*
 * the follow define determines how many PTPs should be set up for the
 * kernel by locore.s at boot time.  this should be large enough to
 * get the VM system running.  once the VM system is running, the
 * pmap module can add more PTPs to the kernel area on demand.
 */

#ifndef NKPTP
#define NKPTP		4	/* 16MB to start */
#endif
#define NKPTP_MIN	4	/* smallest value we allow */
#define NKPTP_MAX	(1024 - (KERNBASE/NBPD) - 1)
				/* largest value (-1 for APTP space) */

/*
 * pdei/ptei: generate index into PDP/PTP from a VA
 */
#define	pdei(VA)	(((VA) & PD_MASK) >> PDSHIFT)
#define	ptei(VA)	(((VA) & PT_MASK) >> PGSHIFT)

/*
 * PTP macros:
 *   a PTP's index is the PD index of the PDE that points to it
 *   a PTP's offset is the byte-offset in the PTE space that this PTP is at
 *   a PTP's VA is the first VA mapped by that PTP
 *
 * note that NBPG == number of bytes in a PTP (4096 bytes == 1024 entries)
 *           NBPD == number of bytes a PTP can map (4MB)
 */

#define ptp_i2o(I)	((I) * NBPG)	/* index => offset */
#define ptp_o2i(O)	((O) / NBPG)	/* offset => index */
#define ptp_i2v(I)	((I) * NBPD)	/* index => VA */
#define ptp_v2i(V)	((V) / NBPD)	/* VA => index (same as pdei) */

/*
 * PG_AVAIL usage: we make use of the ignored bits of the PTE
 */

#define PG_W		PG_AVAIL1	/* "wired" mapping */
#define PG_PVLIST	PG_AVAIL2	/* mapping has entry on pvlist */
/* PG_AVAIL3 not used */

#ifdef _KERNEL
/*
 * pmap data structures: see pmap.c for details of locking.
 */

struct pmap;
typedef struct pmap *pmap_t;

/*
 * we maintain a list of all non-kernel pmaps
 */

LIST_HEAD(pmap_head, pmap); /* struct pmap_head: head of a pmap list */

/*
 * the pmap structure
 *
 * note that the pm_obj contains the simple_lock, the reference count,
 * page list, and number of PTPs within the pmap.
 */

struct pmap {
	struct uvm_object pm_obj;	/* object (lck by object lock) */
#define	pm_lock	pm_obj.vmobjlock
	LIST_ENTRY(pmap) pm_list;	/* list (lck by pm_list lock) */
	pd_entry_t *pm_pdir;		/* VA of PD (lck by object lock) */
	u_int32_t pm_pdirpa;		/* PA of PD (read-only after create) */
	struct vm_page *pm_ptphint;	/* pointer to a PTP in our pmap */
	struct pmap_statistics pm_stats;  /* pmap stats (lck by object lock) */

	int pm_flags;			/* see below */

	union descriptor *pm_ldt;	/* user-set LDT */
	int pm_ldt_len;			/* number of LDT entries */
	int pm_ldt_sel;			/* LDT selector */
};

/* pm_flags */
#define	PMF_USER_LDT	0x01	/* pmap has user-set LDT */

/*
 * for each managed physical page we maintain a list of <PMAP,VA>'s
 * which it is mapped at.  the list is headed by a pv_head structure.
 * there is one pv_head per managed phys page (allocated at boot time).
 * the pv_head structure points to a list of pv_entry structures (each