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      1 /*	$NetBSD: uvm_object.h,v 1.40 2024/02/05 21:46:07 andvar Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1997 Charles D. Cranor and Washington University.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  *
     27  * from: Id: uvm_object.h,v 1.1.2.2 1998/01/04 22:44:51 chuck Exp
     28  */
     29 
     30 #ifndef _UVM_UVM_OBJECT_H_
     31 #define _UVM_UVM_OBJECT_H_
     32 
     33 #include <sys/queue.h>
     34 #include <sys/radixtree.h>
     35 #include <uvm/uvm_pglist.h>
     36 
     37 /*
     38  * The UVM memory object interface.  Notes:
     39  *
     40  * A UVM memory object represents a list of pages, which are managed by
     41  * the object's pager operations (uvm_object::pgops).  All pages belonging
     42  * to an object are owned by it and thus protected by the object lock.
     43  *
     44  * The lock (uvm_object::vmobjlock) may be shared amongst the UVM objects.
     45  * By default, the lock is allocated dynamically using mutex_obj(9) cache.
     46  * Lock sharing is normally used when there is an underlying object.  For
     47  * example, vnode representing a file may have an underlying node, which
     48  * is the case for tmpfs and layered file systems.  In such case, vnode's
     49  * UVM object and the underlying UVM object shares the lock (note that the
     50  * vnode_t::v_interlock points to uvm_object::vmobjlock).
     51  *
     52  * The reference count is managed atomically for the anonymous UVM objects.
     53  * For other objects, it is arbitrary (may use the lock or atomics).
     54  */
     55 
     56 struct krwlock;
     57 struct uvm_object {
     58 	struct krwlock *	vmobjlock;	/* lock on object */
     59 	const struct uvm_pagerops *pgops;	/* pager ops */
     60 	int			uo_npages;	/* # of pages in uo_pages */
     61 	unsigned		uo_refs;	/* reference count */
     62 	struct radix_tree	uo_pages;	/* tree of pages */
     63 	LIST_HEAD(,ubc_map)	uo_ubc;		/* ubc mappings */
     64 };
     65 
     66 /*
     67  * tags for uo_pages
     68  */
     69 
     70 #define	UVM_PAGE_DIRTY_TAG	1	/* might be dirty (!PG_CLEAN) */
     71 #define	UVM_PAGE_WRITEBACK_TAG	2	/* being written back */
     72 
     73 /*
     74  * UVM_OBJ_KERN is a 'special' uo_refs value which indicates that the
     75  * object is a kernel memory object rather than a normal one (kernel
     76  * memory objects don't have reference counts -- they never die).
     77  *
     78  * this value is used to detected kernel object mappings at uvm_unmap()
     79  * time.   normally when an object is unmapped its pages eventually become
     80  * deactivated and then paged out and/or freed.    this is not useful
     81  * for kernel objects... when a kernel object is unmapped we always want
     82  * to free the resources associated with the mapping.   UVM_OBJ_KERN
     83  * allows us to decide which type of unmapping we want to do.
     84  */
     85 #define UVM_OBJ_KERN		(-2)
     86 
     87 #define	UVM_OBJ_IS_KERN_OBJECT(uobj)					\
     88 	((uobj)->uo_refs == UVM_OBJ_KERN)
     89 
     90 #ifdef _KERNEL
     91 
     92 extern const struct uvm_pagerops uvm_vnodeops;
     93 extern const struct uvm_pagerops uvm_deviceops;
     94 extern const struct uvm_pagerops ubc_pager;
     95 extern const struct uvm_pagerops aobj_pager;
     96 
     97 #define	UVM_OBJ_IS_VNODE(uobj)						\
     98 	((uobj)->pgops == &uvm_vnodeops)
     99 
    100 #define	UVM_OBJ_IS_DEVICE(uobj)						\
    101 	((uobj)->pgops == &uvm_deviceops)
    102 
    103 #define	UVM_OBJ_IS_VTEXT(uobj)						\
    104 	(UVM_OBJ_IS_VNODE(uobj) && uvn_text_p(uobj))
    105 
    106 #define	UVM_OBJ_IS_CLEAN(uobj)						\
    107 	(UVM_OBJ_IS_VNODE(uobj) && uvm_obj_clean_p(uobj))
    108 
    109 /*
    110  * UVM_OBJ_NEEDS_WRITEFAULT: true if the uobj needs to detect modification.
    111  * (ie. wants to avoid writable user mappings.)
    112  *
    113  * XXX bad name
    114  */
    115 
    116 #define	UVM_OBJ_NEEDS_WRITEFAULT(uobj)					\
    117 	(UVM_OBJ_IS_VNODE(uobj) && uvm_obj_clean_p(uobj))
    118 
    119 #define	UVM_OBJ_IS_AOBJ(uobj)						\
    120 	((uobj)->pgops == &aobj_pager)
    121 
    122 #endif /* _KERNEL */
    123 
    124 #endif /* _UVM_UVM_OBJECT_H_ */
    125