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

     /*      $NetBSD: uvm_object.h,v 1.39 2020/08/14 09:06:15 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.
     *
     * 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.
     *
     * from: Id: uvm_object.h,v 1.1.2.2 1998/01/04 22:44:51 chuck Exp
     */
    
    #ifndef _UVM_UVM_OBJECT_H_
    #define _UVM_UVM_OBJECT_H_
    
    #include <sys/queue.h>
    #include <sys/radixtree.h>
    #include <uvm/uvm_pglist.h>
    
    /*
     * The UVM memory object interface.  Notes:
     *
     * A UVM memory object represents a list of pages, which are managed by
     * the object's pager operations (uvm_object::pgops).  All pages belonging
     * to an object are owned by it and thus protected by the object lock.
     *
     * The lock (uvm_object::vmobjlock) may be shared amongst the UVM objects.
     * By default, the lock is allocated dynamically using mutex_obj(9) cache.
     * Lock sharing is normally used when there is an underlying object.  For
     * example, vnode representing a file may have an underlying node, which
     * is the case for tmpfs and layered file systems.  In such case, vnode's
     * UVM object and the underlying UVM object shares the lock (note that the
     * vnode_t::v_interlock points to uvm_object::vmobjlock).
     *
     * The reference count is managed atomically for the anonymous UVM objects.
     * For other objects, it is arbitrary (may use the lock or atomics).
     */
    
    struct krwlock;
    struct uvm_object {
            struct krwlock *        vmobjlock;      /* lock on object */
            const struct uvm_pagerops *pgops;       /* pager ops */
            int                     uo_npages;      /* # of pages in uo_pages */
            unsigned                uo_refs;        /* reference count */
            struct radix_tree       uo_pages;       /* tree of pages */
            LIST_HEAD(,ubc_map)     uo_ubc;         /* ubc mappings */
    };
    
    /*
     * tags for uo_pages
     */
    
    #define UVM_PAGE_DIRTY_TAG      1       /* might be dirty (!PG_CLEAN) */
    #define UVM_PAGE_WRITEBACK_TAG  2       /* being written back */
    
    /*
     * UVM_OBJ_KERN is a 'special' uo_refs value which indicates that the
     * object is a kernel memory object rather than a normal one (kernel
     * memory objects don't have reference counts -- they never die).
     *
     * this value is used to detected kernel object mappings at uvm_unmap()
     * time.   normally when an object is unmapped its pages eventaully become
     * deactivated and then paged out and/or freed.    this is not useful
     * for kernel objects... when a kernel object is unmapped we always want
     * to free the resources associated with the mapping.   UVM_OBJ_KERN
     * allows us to decide which type of unmapping we want to do.
     */
    #define UVM_OBJ_KERN            (-2)
    
    #define UVM_OBJ_IS_KERN_OBJECT(uobj)                                    \
            ((uobj)->uo_refs == UVM_OBJ_KERN)
    
    #ifdef _KERNEL
    
    extern const struct uvm_pagerops uvm_vnodeops;
    extern const struct uvm_pagerops uvm_deviceops;
    extern const struct uvm_pagerops ubc_pager;
    extern const struct uvm_pagerops aobj_pager;
    
    #define UVM_OBJ_IS_VNODE(uobj)                                          \
            ((uobj)->pgops == &uvm_vnodeops)
    
   #define UVM_OBJ_IS_DEVICE(uobj)                                         \
           ((uobj)->pgops == &uvm_deviceops)
   
   #define UVM_OBJ_IS_VTEXT(uobj)                                          \
           (UVM_OBJ_IS_VNODE(uobj) && uvn_text_p(uobj))
   
   #define UVM_OBJ_IS_CLEAN(uobj)                                          \
           (UVM_OBJ_IS_VNODE(uobj) && uvm_obj_clean_p(uobj))
   
   /*
    * UVM_OBJ_NEEDS_WRITEFAULT: true if the uobj needs to detect modification.
    * (ie. wants to avoid writable user mappings.)
    *
    * XXX bad name
    */
   
   #define UVM_OBJ_NEEDS_WRITEFAULT(uobj)                                  \
           (UVM_OBJ_IS_VNODE(uobj) && uvm_obj_clean_p(uobj))
   
   #define UVM_OBJ_IS_AOBJ(uobj)                                           \
           ((uobj)->pgops == &aobj_pager)
   
   #endif /* _KERNEL */
   
   #endif /* _UVM_UVM_OBJECT_H_ */

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