FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_page.h

     /*-
      * 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.
     * 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: releng/9.0/sys/vm/vm_page.h 226319 2011-10-12 20:08:25Z kib $
     */
    
    /*
     *      Resident memory system definitions.
     */
    
    #ifndef _VM_PAGE_
    #define _VM_PAGE_
    
    #include <vm/pmap.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.
     *
     *      In general, operations on this structure's mutable fields are
     *      synchronized using either one of or a combination of the lock on the
     *      object that the page belongs to (O), the pool lock for the page (P),
     *      or the lock for either the free or paging queues (Q).  If a field is
     *      annotated below with two of these locks, then holding either lock is
     *      sufficient for read access, but both locks are required for write
     *      access.
     *
    *      In contrast, the synchronization of accesses to the page's
    *      dirty field is machine dependent (M).  In the
    *      machine-independent layer, the lock on the object that the
    *      page belongs to must be held in order to operate on the field.
    *      However, the pmap layer is permitted to set all bits within
    *      the field without holding that lock.  If the underlying
    *      architecture does not support atomic read-modify-write
    *      operations on the field's type, then the machine-independent
    *      layer uses a 32-bit atomic on the aligned 32-bit word that
    *      contains the dirty field.  In the machine-independent layer,
    *      the implementation of read-modify-write operations on the
    *      field is encapsulated in vm_page_clear_dirty_mask().
    */
   
   TAILQ_HEAD(pglist, vm_page);
   
   struct vm_page {
           TAILQ_ENTRY(vm_page) pageq;     /* queue info for FIFO queue or free list (Q) */
           TAILQ_ENTRY(vm_page) listq;     /* pages in same object (O)     */
           struct vm_page *left;           /* splay tree link (O)          */
           struct vm_page *right;          /* splay tree link (O)          */
   
           vm_object_t object;             /* which object am I in (O,P)*/
           vm_pindex_t pindex;             /* offset into object (O,P) */
           vm_paddr_t phys_addr;           /* physical address of page */
           struct md_page md;              /* machine dependant stuff */
           uint8_t queue;                  /* page queue index (P,Q) */
           int8_t segind;
           short hold_count;               /* page hold count (P) */
           uint8_t order;                  /* index of the buddy queue */
           uint8_t pool;
           u_short cow;                    /* page cow mapping count (P) */
           u_int wire_count;               /* wired down maps refs (P) */
           uint8_t aflags;                 /* access is atomic */
           uint8_t flags;                  /* see below, often immutable after alloc */
           u_short oflags;                 /* page flags (O) */
           u_char  act_count;              /* page usage count (O) */
           u_char  busy;                   /* page busy count (O) */
           /* 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 */
           /* In reality, support for 32KB pages is not fully implemented. */
   #if PAGE_SIZE == 4096
           uint8_t valid;                  /* map of valid DEV_BSIZE chunks (O) */
           uint8_t dirty;                  /* map of dirty DEV_BSIZE chunks (M) */
   #elif PAGE_SIZE == 8192
           uint16_t valid;                 /* map of valid DEV_BSIZE chunks (O) */
           uint16_t dirty;                 /* map of dirty DEV_BSIZE chunks (M) */
   #elif PAGE_SIZE == 16384
           uint32_t valid;                 /* map of valid DEV_BSIZE chunks (O) */
           uint32_t dirty;                 /* map of dirty DEV_BSIZE chunks (M) */
   #elif PAGE_SIZE == 32768
           uint64_t valid;                 /* map of valid DEV_BSIZE chunks (O) */
           uint64_t dirty;                 /* map of dirty DEV_BSIZE chunks (M) */
   #endif
   };
   
   /*
    * Page flags stored in oflags:
    *
    * Access to these page flags is synchronized by the lock on the object
    * containing the page (O).
    *
    * Note: VPO_UNMANAGED (used by OBJT_DEVICE, OBJT_PHYS and OBJT_SG)
    *       indicates that the page is not under PV management but
    *       otherwise should be treated as a normal page.  Pages not
    *       under PV management cannot be paged out via the
    *       object/vm_page_t because there is no knowledge of their pte
    *       mappings, and such pages are also not on any PQ queue.
    *
    */
   #define VPO_BUSY        0x0001  /* page is in transit */
   #define VPO_WANTED      0x0002  /* someone is waiting for page */
   #define VPO_UNMANAGED   0x0004          /* No PV management for page */
   #define VPO_SWAPINPROG  0x0200  /* swap I/O in progress on page */
   #define VPO_NOSYNC      0x0400  /* do not collect for syncer */
   
   #define PQ_NONE         255
   #define PQ_INACTIVE     0
   #define PQ_ACTIVE       1
   #define PQ_HOLD         2
   #define PQ_COUNT        3
   
   struct vpgqueues {
           struct pglist pl;
           int     *cnt;
   };
   
   extern struct vpgqueues vm_page_queues[PQ_COUNT];
   
   struct vpglocks {
           struct mtx      data;
           char            pad[CACHE_LINE_SIZE - sizeof(struct mtx)];
   } __aligned(CACHE_LINE_SIZE);
   
   extern struct vpglocks vm_page_queue_free_lock;
   extern struct vpglocks pa_lock[];
   
   #if defined(__arm__)
   #define PDRSHIFT        PDR_SHIFT
   #elif !defined(PDRSHIFT)
   #define PDRSHIFT        21
   #endif
   
   #define pa_index(pa)    ((pa) >> PDRSHIFT)
   #define PA_LOCKPTR(pa)  &pa_lock[pa_index((pa)) % PA_LOCK_COUNT].data
   #define PA_LOCKOBJPTR(pa)       ((struct lock_object *)PA_LOCKPTR((pa)))
   #define PA_LOCK(pa)     mtx_lock(PA_LOCKPTR(pa))
   #define PA_TRYLOCK(pa)  mtx_trylock(PA_LOCKPTR(pa))
   #define PA_UNLOCK(pa)   mtx_unlock(PA_LOCKPTR(pa))
   #define PA_UNLOCK_COND(pa)                      \
           do {                                    \
                   if ((pa) != 0) {                \
                           PA_UNLOCK((pa));        \
                           (pa) = 0;               \
                   }                               \
           } while (0)
   
   #define PA_LOCK_ASSERT(pa, a)   mtx_assert(PA_LOCKPTR(pa), (a))
   
   #define vm_page_lockptr(m)      (PA_LOCKPTR(VM_PAGE_TO_PHYS((m))))
   #define vm_page_lock(m)         mtx_lock(vm_page_lockptr((m)))
   #define vm_page_unlock(m)       mtx_unlock(vm_page_lockptr((m)))
   #define vm_page_trylock(m)      mtx_trylock(vm_page_lockptr((m)))
   #define vm_page_lock_assert(m, a)       mtx_assert(vm_page_lockptr((m)), (a))
   
   #define vm_page_queue_free_mtx  vm_page_queue_free_lock.data
   /*
    * These are the flags defined for vm_page.
    *
    * aflags are updated by atomic accesses. Use the vm_page_aflag_set()
    * and vm_page_aflag_clear() functions to set and clear the flags.
    *
    * PGA_REFERENCED may be cleared only if the object containing the page is
    * locked.
    *
    * PGA_WRITEABLE is set exclusively on managed pages by pmap_enter().  When it
    * does so, the page must be VPO_BUSY.
    */
   #define PGA_WRITEABLE   0x01            /* page may be mapped writeable */
   #define PGA_REFERENCED  0x02            /* page has been referenced */
   
   /*
    * Page flags.  If changed at any other time than page allocation or
    * freeing, the modification must be protected by the vm_page lock.
    */
   #define PG_CACHED       0x01            /* page is cached */
   #define PG_FREE         0x02            /* page is free */
   #define PG_FICTITIOUS   0x04            /* physical page doesn't exist (O) */
   #define PG_ZERO         0x08            /* page is zeroed */
   #define PG_MARKER       0x10            /* special queue marker page */
   #define PG_SLAB         0x20            /* object pointer is actually a slab */
   #define PG_WINATCFLS    0x40            /* flush dirty page on inactive q */
   
   /*
    * Misc constants.
    */
   #define ACT_DECLINE             1
   #define ACT_ADVANCE             3
   #define ACT_INIT                5
   #define ACT_MAX                 64
   
   #ifdef _KERNEL
   
   #include <vm/vm_param.h>
   
   /*
    * Each pageable resident page falls into one of five lists:
    *
    *      free
    *              Available for allocation now.
    *
    *      cache
    *              Almost available for allocation. Still associated with
    *              an object, but clean and immediately freeable.
    *
    *      hold
    *              Will become free after a pending I/O operation
    *              completes.
    *
    * The following lists are LRU sorted:
    *
    *      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.
    *
    */
   
   struct vnode;
   extern int vm_page_zero_count;
   
   extern vm_page_t vm_page_array;         /* First resident page in table */
   extern int vm_page_array_size;          /* number of vm_page_t's */
   extern long first_page;                 /* first physical page number */
   
   #define VM_PAGE_IS_FREE(m)      (((m)->flags & PG_FREE) != 0)
   
   #define VM_PAGE_TO_PHYS(entry)  ((entry)->phys_addr)
   
   vm_page_t vm_phys_paddr_to_vm_page(vm_paddr_t pa);
   
   static __inline vm_page_t PHYS_TO_VM_PAGE(vm_paddr_t pa);
   
   static __inline vm_page_t
   PHYS_TO_VM_PAGE(vm_paddr_t pa)
   {
   #ifdef VM_PHYSSEG_SPARSE
           return (vm_phys_paddr_to_vm_page(pa));
   #elif defined(VM_PHYSSEG_DENSE)
           return (&vm_page_array[atop(pa) - first_page]);
   #else
   #error "Either VM_PHYSSEG_DENSE or VM_PHYSSEG_SPARSE must be defined."
   #endif
   }
   
   extern struct vpglocks vm_page_queue_lock;
   
   #define vm_page_queue_mtx       vm_page_queue_lock.data
   #define vm_page_lock_queues()   mtx_lock(&vm_page_queue_mtx)
   #define vm_page_unlock_queues() mtx_unlock(&vm_page_queue_mtx)
   
   #if PAGE_SIZE == 4096
   #define VM_PAGE_BITS_ALL 0xffu
   #elif PAGE_SIZE == 8192
   #define VM_PAGE_BITS_ALL 0xffffu
   #elif PAGE_SIZE == 16384
   #define VM_PAGE_BITS_ALL 0xffffffffu
   #elif PAGE_SIZE == 32768
   #define VM_PAGE_BITS_ALL 0xfffffffffffffffflu
   #endif
   
   /* page allocation classes: */
   #define VM_ALLOC_NORMAL         0
   #define VM_ALLOC_INTERRUPT      1
   #define VM_ALLOC_SYSTEM         2
   #define VM_ALLOC_CLASS_MASK     3
   /* page allocation flags: */
   #define VM_ALLOC_WIRED          0x0020  /* non pageable */
   #define VM_ALLOC_ZERO           0x0040  /* Try to obtain a zeroed page */
   #define VM_ALLOC_RETRY          0x0080  /* Mandatory with vm_page_grab() */
   #define VM_ALLOC_NOOBJ          0x0100  /* No associated object */
   #define VM_ALLOC_NOBUSY         0x0200  /* Do not busy the page */
   #define VM_ALLOC_IFCACHED       0x0400  /* Fail if the page is not cached */
   #define VM_ALLOC_IFNOTCACHED    0x0800  /* Fail if the page is cached */
   #define VM_ALLOC_IGN_SBUSY      0x1000  /* vm_page_grab() only */
   
   #define VM_ALLOC_COUNT_SHIFT    16
   #define VM_ALLOC_COUNT(count)   ((count) << VM_ALLOC_COUNT_SHIFT)
   
   void vm_page_aflag_set(vm_page_t m, uint8_t bits);
   void vm_page_aflag_clear(vm_page_t m, uint8_t bits);
   void vm_page_busy(vm_page_t m);
   void vm_page_flash(vm_page_t m);
   void vm_page_io_start(vm_page_t m);
   void vm_page_io_finish(vm_page_t m);
   void vm_page_hold(vm_page_t mem);
   void vm_page_unhold(vm_page_t mem);
   void vm_page_free(vm_page_t m);
   void vm_page_free_zero(vm_page_t m);
   void vm_page_dirty(vm_page_t m);
   void vm_page_wakeup(vm_page_t m);
   
   void vm_pageq_remove(vm_page_t m);
   
   void vm_page_activate (vm_page_t);
   vm_page_t vm_page_alloc (vm_object_t, vm_pindex_t, int);
   vm_page_t vm_page_alloc_freelist(int, int);
   struct vnode *vm_page_alloc_init(vm_page_t);
   vm_page_t vm_page_grab (vm_object_t, vm_pindex_t, int);
   void vm_page_cache(vm_page_t);
   void vm_page_cache_free(vm_object_t, vm_pindex_t, vm_pindex_t);
   void vm_page_cache_remove(vm_page_t);
   void vm_page_cache_transfer(vm_object_t, vm_pindex_t, vm_object_t);
   int vm_page_try_to_cache (vm_page_t);
   int vm_page_try_to_free (vm_page_t);
   void vm_page_dontneed(vm_page_t);
   void vm_page_deactivate (vm_page_t);
   vm_page_t vm_page_find_least(vm_object_t, vm_pindex_t);
   vm_page_t vm_page_getfake(vm_paddr_t paddr, vm_memattr_t memattr);
   void vm_page_insert (vm_page_t, vm_object_t, vm_pindex_t);
   vm_page_t vm_page_lookup (vm_object_t, vm_pindex_t);
   vm_page_t vm_page_next(vm_page_t m);
   int vm_page_pa_tryrelock(pmap_t, vm_paddr_t, vm_paddr_t *);
   vm_page_t vm_page_prev(vm_page_t m);
   void vm_page_putfake(vm_page_t m);
   void vm_page_reference(vm_page_t m);
   void vm_page_remove (vm_page_t);
   void vm_page_rename (vm_page_t, vm_object_t, vm_pindex_t);
   void vm_page_requeue(vm_page_t m);
   void vm_page_set_valid(vm_page_t m, int base, int size);
   void vm_page_sleep(vm_page_t m, const char *msg);
   vm_page_t vm_page_splay(vm_pindex_t, vm_page_t);
   vm_offset_t vm_page_startup(vm_offset_t vaddr);
   void vm_page_unhold_pages(vm_page_t *ma, int count);
   void vm_page_unwire (vm_page_t, int);
   void vm_page_updatefake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr);
   void vm_page_wire (vm_page_t);
   void vm_page_set_validclean (vm_page_t, int, int);
   void vm_page_clear_dirty (vm_page_t, int, int);
   void vm_page_set_invalid (vm_page_t, int, int);
   int vm_page_is_valid (vm_page_t, int, int);
   void vm_page_test_dirty (vm_page_t);
   int vm_page_bits (int, int);
   void vm_page_zero_invalid(vm_page_t m, boolean_t setvalid);
   void vm_page_free_toq(vm_page_t m);
   void vm_page_zero_idle_wakeup(void);
   void vm_page_cowfault (vm_page_t);
   int vm_page_cowsetup(vm_page_t);
   void vm_page_cowclear (vm_page_t);
   
   #ifdef INVARIANTS
   void vm_page_object_lock_assert(vm_page_t m);
   #define VM_PAGE_OBJECT_LOCK_ASSERT(m)   vm_page_object_lock_assert(m)
   #else
   #define VM_PAGE_OBJECT_LOCK_ASSERT(m)   (void)0
   #endif
   
   /*
    *      vm_page_sleep_if_busy:
    *
    *      Sleep and release the page queues lock if VPO_BUSY is set or,
    *      if also_m_busy is TRUE, busy is non-zero.  Returns TRUE if the
    *      thread slept and the page queues lock was released.
    *      Otherwise, retains the page queues lock and returns FALSE.
    *
    *      The object containing the given page must be locked.
    */
   static __inline int
   vm_page_sleep_if_busy(vm_page_t m, int also_m_busy, const char *msg)
   {
   
           if ((m->oflags & VPO_BUSY) || (also_m_busy && m->busy)) {
                   vm_page_sleep(m, msg);
                   return (TRUE);
           }
           return (FALSE);
   }
   
   /*
    *      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)
   {
   
           VM_PAGE_OBJECT_LOCK_ASSERT(m);
           m->dirty = 0;
   }
   
   #endif                          /* _KERNEL */
   #endif                          /* !_VM_PAGE_ */

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