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      1 /*	$NetBSD: uvm_fault_i.h,v 1.33 2020/02/23 15:46:43 ad 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 void uvmfault_update_stats(struct uvm_faultinfo *);
     37 
     38 
     39 /*
     40  * uvmfault_unlockmaps: unlock the maps
     41  */
     42 
     43 static __inline void
     44 uvmfault_unlockmaps(struct uvm_faultinfo *ufi, bool write_locked)
     45 {
     46 	/*
     47 	 * ufi can be NULL when this isn't really a fault,
     48 	 * but merely paging in anon data.
     49 	 */
     50 
     51 	if (ufi == NULL) {
     52 		return;
     53 	}
     54 
     55 #ifndef __HAVE_NO_PMAP_STATS
     56 	uvmfault_update_stats(ufi);
     57 #endif
     58 	if (write_locked) {
     59 		vm_map_unlock(ufi->map);
     60 	} else {
     61 		vm_map_unlock_read(ufi->map);
     62 	}
     63 }
     64 
     65 /*
     66  * uvmfault_unlockall: unlock everything passed in.
     67  *
     68  * => maps must be read-locked (not write-locked).
     69  */
     70 
     71 static __inline void
     72 uvmfault_unlockall(struct uvm_faultinfo *ufi, struct vm_amap *amap,
     73     struct uvm_object *uobj)
     74 {
     75 
     76 	if (uobj)
     77 		rw_exit(uobj->vmobjlock);
     78 	if (amap)
     79 		amap_unlock(amap);
     80 	uvmfault_unlockmaps(ufi, false);
     81 }
     82 
     83 /*
     84  * uvmfault_lookup: lookup a virtual address in a map
     85  *
     86  * => caller must provide a uvm_faultinfo structure with the IN
     87  *	params properly filled in
     88  * => we will lookup the map entry (handling submaps) as we go
     89  * => if the lookup is a success we will return with the maps locked
     90  * => if "write_lock" is true, we write_lock the map, otherwise we only
     91  *	get a read lock.
     92  * => note that submaps can only appear in the kernel and they are
     93  *	required to use the same virtual addresses as the map they
     94  *	are referenced by (thus address translation between the main
     95  *	map and the submap is unnecessary).
     96  */
     97 
     98 static __inline bool
     99 uvmfault_lookup(struct uvm_faultinfo *ufi, bool write_lock)
    100 {
    101 	struct vm_map *tmpmap;
    102 
    103 	/*
    104 	 * init ufi values for lookup.
    105 	 */
    106 
    107 	ufi->map = ufi->orig_map;
    108 	ufi->size = ufi->orig_size;
    109 
    110 	/*
    111 	 * keep going down levels until we are done.   note that there can
    112 	 * only be two levels so we won't loop very long.
    113 	 */
    114 
    115 	for (;;) {
    116 		/*
    117 		 * lock map
    118 		 */
    119 		if (write_lock) {
    120 			vm_map_lock(ufi->map);
    121 		} else {
    122 			vm_map_lock_read(ufi->map);
    123 		}
    124 
    125 		/*
    126 		 * lookup
    127 		 */
    128 		if (!uvm_map_lookup_entry(ufi->map, ufi->orig_rvaddr,
    129 		    &ufi->entry)) {
    130 			uvmfault_unlockmaps(ufi, write_lock);
    131 			return(false);
    132 		}
    133 
    134 		/*
    135 		 * reduce size if necessary
    136 		 */
    137 		if (ufi->entry->end - ufi->orig_rvaddr < ufi->size)
    138 			ufi->size = ufi->entry->end - ufi->orig_rvaddr;
    139 
    140 		/*
    141 		 * submap?    replace map with the submap and lookup again.
    142 		 * note: VAs in submaps must match VAs in main map.
    143 		 */
    144 		if (UVM_ET_ISSUBMAP(ufi->entry)) {
    145 			tmpmap = ufi->entry->object.sub_map;
    146 			if (write_lock) {
    147 				vm_map_unlock(ufi->map);
    148 			} else {
    149 				vm_map_unlock_read(ufi->map);
    150 			}
    151 			ufi->map = tmpmap;
    152 			continue;
    153 		}
    154 
    155 		/*
    156 		 * got it!
    157 		 */
    158 
    159 		ufi->mapv = ufi->map->timestamp;
    160 		return(true);
    161 
    162 	}	/* while loop */
    163 
    164 	/*NOTREACHED*/
    165 }
    166 
    167 /*
    168  * uvmfault_relock: attempt to relock the same version of the map
    169  *
    170  * => fault data structures should be unlocked before calling.
    171  * => if a success (true) maps will be locked after call.
    172  */
    173 
    174 static __inline bool
    175 uvmfault_relock(struct uvm_faultinfo *ufi)
    176 {
    177 	/*
    178 	 * ufi can be NULL when this isn't really a fault,
    179 	 * but merely paging in anon data.
    180 	 */
    181 
    182 	if (ufi == NULL) {
    183 		return true;
    184 	}
    185 
    186 	cpu_count(CPU_COUNT_FLTRELCK, 1);
    187 
    188 	/*
    189 	 * relock map.   fail if version mismatch (in which case nothing
    190 	 * gets locked).
    191 	 */
    192 
    193 	vm_map_lock_read(ufi->map);
    194 	if (ufi->mapv != ufi->map->timestamp) {
    195 		vm_map_unlock_read(ufi->map);
    196 		return(false);
    197 	}
    198 
    199 	cpu_count(CPU_COUNT_FLTRELCKOK, 1);
    200 	return(true);
    201 }
    202 
    203 #endif /* _UVM_UVM_FAULT_I_H_ */
    204