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uvm_fault_i.h revision 1.27 
      1 /*	$NetBSD: uvm_fault_i.h,v 1.27 2011/06/12 03:36:03 rmind 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_fault_i.h,v 1.1.6.1 1997/12/08 16:07:12 chuck Exp
     28  */
     29 
     30 #ifndef _UVM_UVM_FAULT_I_H_
     31 #define _UVM_UVM_FAULT_I_H_
     32 
     33 /*
     34  * uvm_fault_i.h: fault inline functions
     35  */
     36 
     37 /*
     38  * uvmfault_unlockmaps: unlock the maps
     39  */
     40 
     41 static inline void
     42 uvmfault_unlockmaps(struct uvm_faultinfo *ufi, bool write_locked)
     43 {
     44 	/*
     45 	 * ufi can be NULL when this isn't really a fault,
     46 	 * but merely paging in anon data.
     47 	 */
     48 
     49 	if (ufi == NULL) {
     50 		return;
     51 	}
     52 
     53 	if (write_locked) {
     54 		vm_map_unlock(ufi->map);
     55 	} else {
     56 		vm_map_unlock_read(ufi->map);
     57 	}
     58 }
     59 
     60 /*
     61  * uvmfault_unlockall: unlock everything passed in.
     62  *
     63  * => maps must be read-locked (not write-locked).
     64  */
     65 
     66 static inline void
     67 uvmfault_unlockall(struct uvm_faultinfo *ufi, struct vm_amap *amap,
     68     struct uvm_object *uobj)
     69 {
     70 
     71 	if (uobj)
     72 		mutex_exit(uobj->vmobjlock);
     73 	if (amap)
     74 		amap_unlock(amap);
     75 	uvmfault_unlockmaps(ufi, false);
     76 }
     77 
     78 /*
     79  * uvmfault_lookup: lookup a virtual address in a map
     80  *
     81  * => caller must provide a uvm_faultinfo structure with the IN
     82  *	params properly filled in
     83  * => we will lookup the map entry (handling submaps) as we go
     84  * => if the lookup is a success we will return with the maps locked
     85  * => if "write_lock" is true, we write_lock the map, otherwise we only
     86  *	get a read lock.
     87  * => note that submaps can only appear in the kernel and they are
     88  *	required to use the same virtual addresses as the map they
     89  *	are referenced by (thus address translation between the main
     90  *	map and the submap is unnecessary).
     91  */
     92 
     93 static inline bool
     94 uvmfault_lookup(struct uvm_faultinfo *ufi, bool write_lock)
     95 {
     96 	struct vm_map *tmpmap;
     97 
     98 	/*
     99 	 * init ufi values for lookup.
    100 	 */
    101 
    102 	ufi->map = ufi->orig_map;
    103 	ufi->size = ufi->orig_size;
    104 
    105 	/*
    106 	 * keep going down levels until we are done.   note that there can
    107 	 * only be two levels so we won't loop very long.
    108 	 */
    109 
    110 	/*CONSTCOND*/
    111 	while (1) {
    112 		/*
    113 		 * Make sure this is not an "interrupt safe" map.
    114 		 * Such maps are never supposed to be involved in
    115 		 * a fault.
    116 		 */
    117 		if (ufi->map->flags & VM_MAP_INTRSAFE)
    118 			return (false);
    119 
    120 		/*
    121 		 * lock map
    122 		 */
    123 		if (write_lock) {
    124 			vm_map_lock(ufi->map);
    125 		} else {
    126 			vm_map_lock_read(ufi->map);
    127 		}
    128 
    129 		/*
    130 		 * lookup
    131 		 */
    132 		if (!uvm_map_lookup_entry(ufi->map, ufi->orig_rvaddr,
    133 		    &ufi->entry)) {
    134 			uvmfault_unlockmaps(ufi, write_lock);
    135 			return(false);
    136 		}
    137 
    138 		/*
    139 		 * reduce size if necessary
    140 		 */
    141 		if (ufi->entry->end - ufi->orig_rvaddr < ufi->size)
    142 			ufi->size = ufi->entry->end - ufi->orig_rvaddr;
    143 
    144 		/*
    145 		 * submap?    replace map with the submap and lookup again.
    146 		 * note: VAs in submaps must match VAs in main map.
    147 		 */
    148 		if (UVM_ET_ISSUBMAP(ufi->entry)) {
    149 			tmpmap = ufi->entry->object.sub_map;
    150 			if (write_lock) {
    151 				vm_map_unlock(ufi->map);
    152 			} else {
    153 				vm_map_unlock_read(ufi->map);
    154 			}
    155 			ufi->map = tmpmap;
    156 			continue;
    157 		}
    158 
    159 		/*
    160 		 * got it!
    161 		 */
    162 
    163 		ufi->mapv = ufi->map->timestamp;
    164 		return(true);
    165 
    166 	}	/* while loop */
    167 
    168 	/*NOTREACHED*/
    169 }
    170 
    171 /*
    172  * uvmfault_relock: attempt to relock the same version of the map
    173  *
    174  * => fault data structures should be unlocked before calling.
    175  * => if a success (true) maps will be locked after call.
    176  */
    177 
    178 static inline bool
    179 uvmfault_relock(struct uvm_faultinfo *ufi)
    180 {
    181 	/*
    182 	 * ufi can be NULL when this isn't really a fault,
    183 	 * but merely paging in anon data.
    184 	 */
    185 
    186 	if (ufi == NULL) {
    187 		return true;
    188 	}
    189 
    190 	uvmexp.fltrelck++;
    191 
    192 	/*
    193 	 * relock map.   fail if version mismatch (in which case nothing
    194 	 * gets locked).
    195 	 */
    196 
    197 	vm_map_lock_read(ufi->map);
    198 	if (ufi->mapv != ufi->map->timestamp) {
    199 		vm_map_unlock_read(ufi->map);
    200 		return(false);
    201 	}
    202 
    203 	uvmexp.fltrelckok++;
    204 	return(true);
    205 }
    206 
    207 #endif /* _UVM_UVM_FAULT_I_H_ */
    208