FreeBSD/Linux Kernel Cross Reference
sys/uvm/uvm_page.h

     /*      $NetBSD: uvm_page.h,v 1.55 2008/06/04 15:06:04 ad 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. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by Charles D. Cranor,
     *      Washington University, 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.
     *
     *      @(#)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@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_
    
    /*
     * uvm_page.h
     */
    
    /*
     *      Resident memory system definitions.
     */
    
    /*
     *      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 red-black tree rooted with the containing
     *              object is 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) [or both].
    */
   
   /*
    * locking note: the mach version of this data structure had bit
    * fields for the flags, and the bit fields were divided into two
    * items (depending on who locked what).  some time, in BSD, the bit
    * fields were dumped and all the flags were lumped into one short.
    * that is fine for a single threaded uniprocessor OS, but bad if you
    * want to actual make use of locking.  so, we've separated things
    * back out again.
    *
    * note the page structure has no lock of its own.
    */
   
   #include <uvm/uvm_extern.h>
   #include <uvm/uvm_pglist.h>
   
   #include <sys/rb.h>
   
   struct vm_page {
           struct rb_node          rb_node;        /* tree of pages in obj (O) */
   
           union {
                   TAILQ_ENTRY(vm_page) queue;
                   LIST_ENTRY(vm_page) list;
           } pageq;                                /* queue info for FIFO
                                                    * queue or free list (P) */
           union {
                   TAILQ_ENTRY(vm_page) queue;
                   LIST_ENTRY(vm_page) list;
           } listq;                                /* pages in same object (O)*/
   
           struct vm_anon          *uanon;         /* anon (O,P) */
           struct uvm_object       *uobject;       /* object (O,P) */
           voff_t                  offset;         /* offset into object (O,P) */
           uint16_t                flags;          /* object flags [O] */
           uint16_t                loan_count;     /* number of active loans
                                                    * to read: [O or P]
                                                    * to modify: [O _and_ P] */
           uint16_t                wire_count;     /* wired down map refs [P] */
           uint16_t                pqflags;        /* page queue flags [P] */
           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
   };
   
   /*
    * These are the flags defined for vm_page.
    */
   
   /*
    * locking rules:
    *   PG_ ==> locked by object lock
    *   PQ_ ==> lock by page queue lock
    *   PQ_FREE is locked by free queue lock and is mutex with all other PQs
    *
    * PG_ZERO is used to indicate that a page has been pre-zero'd.  This flag
    * is only set when the page is on no queues, and is cleared when the page
    * is placed on the free list.
    */
   
   #define PG_BUSY         0x0001          /* page is locked */
   #define PG_WANTED       0x0002          /* someone is waiting for page */
   #define PG_TABLED       0x0004          /* page is in VP table  */
   #define PG_CLEAN        0x0008          /* page has not been modified */
   #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_PAGER1       0x1000          /* pager-specific flag */
   
   #define UVM_PGFLAGBITS \
           "\2\1BUSY\2WANTED\3TABLED\4CLEAN\5PAGEOUT\6RELEASED\7FAKE\10RDONLY" \
           "\11ZERO\15PAGER1"
   
   #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_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 \
           "\2\1FREE\2ANON\3AOBJ\4READAHEAD" \
           "\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  */
           int     free_list;              /* which free list they belong on */
           struct  vm_page *pgs;           /* vm_page structures (from start) */
           struct  vm_page *lastpg;        /* vm_page structure for end */
   #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.
    */
   
   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_rehash(void);
   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_pagewait(struct vm_page *, int);
   void uvm_pagewake(struct vm_page *);
   void uvm_pagewire(struct vm_page *);
   void uvm_pagezero(struct vm_page *);
   
   int uvm_page_lookup_freelist(struct vm_page *);
   
   static struct vm_page *PHYS_TO_VM_PAGE(paddr_t);
   static int vm_physseg_find(paddr_t, int *);
   
   /*
    * macros
    */
   
   #define UVM_PAGE_HASH_PENALTY   4       /* XXX: a guess */
   
   #define uvm_pagehash(obj,off) \
           (((unsigned long)obj+(unsigned long)atop(off)) & uvm.page_hashmask)
   
   #define VM_PAGE_TO_PHYS(entry)  ((entry)->phys_addr)
   
   /*
    * Compute the page color bucket for a given page.
    */
   #define VM_PGCOLOR_BUCKET(pg) \
           (atop(VM_PAGE_TO_PHYS((pg))) & uvmexp.colormask)
   
   /*
    * when VM_PHYSSEG_MAX is 1, we can simplify these functions
    */
   
   /*
    * vm_physseg_find: find vm_physseg structure that belongs to a PA
    */
   static __inline int
   vm_physseg_find(paddr_t pframe, int *offp)
   {
   #if VM_PHYSSEG_MAX == 1
   
           /* 'contig' case */
           if (pframe >= vm_physmem[0].start && pframe < vm_physmem[0].end) {
                   if (offp)
                           *offp = pframe - vm_physmem[0].start;
                   return(0);
           }
           return(-1);
   
   #elif (VM_PHYSSEG_STRAT == VM_PSTRAT_BSEARCH)
           /* binary search for it */
           u_int   start, len, try;
   
           /*
            * if try is too large (thus target is less than try) we reduce
            * the length to trunc(len/2) [i.e. everything smaller than "try"]
            *
            * if the try is too small (thus target is greater than try) then
            * we set the new start to be (try + 1).   this means we need to
            * reduce the length to (round(len/2) - 1).
            *
            * note "adjust" below which takes advantage of the fact that
            *  (round(len/2) - 1) == trunc((len - 1) / 2)
            * for any value of len we may have
            */
   
           for (start = 0, len = vm_nphysseg ; len != 0 ; len = len / 2) {
                   try = start + (len / 2);        /* try in the middle */
   
                   /* start past our try? */
                   if (pframe >= vm_physmem[try].start) {
                           /* was try correct? */
                           if (pframe < vm_physmem[try].end) {
                                   if (offp)
                                           *offp = pframe - vm_physmem[try].start;
                                   return(try);            /* got it */
                           }
                           start = try + 1;        /* next time, start here */
                           len--;                  /* "adjust" */
                   } else {
                           /*
                            * pframe before try, just reduce length of
                            * region, done in "for" loop
                            */
                   }
           }
           return(-1);
   
   #else
           /* linear search for it */
           int     lcv;
   
           for (lcv = 0; lcv < vm_nphysseg; lcv++) {
                   if (pframe >= vm_physmem[lcv].start &&
                       pframe < vm_physmem[lcv].end) {
                           if (offp)
                                   *offp = pframe - vm_physmem[lcv].start;
                           return(lcv);               /* got it */
                   }
           }
           return(-1);
   
   #endif
   }
   
   
   /*
    * IS_VM_PHYSADDR: only used my mips/pmax/pica trap/pmap.
    */
   
   #define IS_VM_PHYSADDR(PA) (vm_physseg_find(atop(PA), NULL) != -1)
   
   /*
    * PHYS_TO_VM_PAGE: find vm_page for a PA.   used by MI code to get vm_pages
    * back from an I/O mapping (ugh!).   used in some MD code as well.
    */
   static __inline struct vm_page *
   PHYS_TO_VM_PAGE(paddr_t pa)
   {
           paddr_t pf = atop(pa);
           int     off;
           int     psi;
   
           psi = vm_physseg_find(pf, &off);
           if (psi != -1)
                   return(&vm_physmem[psi].pgs[off]);
           return(NULL);
   }
   
   #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_ */

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