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Annotation of XNU/osfmk/i386/read_fault.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * The contents of this file constitute Original Code as defined in and
        !             7:  * are subject to the Apple Public Source License Version 1.1 (the
        !             8:  * "License").  You may not use this file except in compliance with the
        !             9:  * License.  Please obtain a copy of the License at
        !            10:  * http://www.apple.com/publicsource and read it before using this file.
        !            11:  * 
        !            12:  * This Original Code and all software distributed under the License are
        !            13:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            14:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            15:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            16:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            17:  * License for the specific language governing rights and limitations
        !            18:  * under the License.
        !            19:  * 
        !            20:  * @APPLE_LICENSE_HEADER_END@
        !            21:  */
        !            22: /*
        !            23:  * @OSF_COPYRIGHT@
        !            24:  */
        !            25: /* 
        !            26:  * Mach Operating System
        !            27:  * Copyright (c) 1991,1990 Carnegie Mellon University
        !            28:  * All Rights Reserved.
        !            29:  * 
        !            30:  * Permission to use, copy, modify and distribute this software and its
        !            31:  * documentation is hereby granted, provided that both the copyright
        !            32:  * notice and this permission notice appear in all copies of the
        !            33:  * software, derivative works or modified versions, and any portions
        !            34:  * thereof, and that both notices appear in supporting documentation.
        !            35:  * 
        !            36:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
        !            37:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
        !            38:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            39:  * 
        !            40:  * Carnegie Mellon requests users of this software to return to
        !            41:  * 
        !            42:  *  Software Distribution Coordinator  or  [email protected]
        !            43:  *  School of Computer Science
        !            44:  *  Carnegie Mellon University
        !            45:  *  Pittsburgh PA 15213-3890
        !            46:  * 
        !            47:  * any improvements or extensions that they make and grant Carnegie Mellon
        !            48:  * the rights to redistribute these changes.
        !            49:  */
        !            50: /*
        !            51:  */
        !            52: 
        !            53: #include <kern/thread.h>
        !            54: #include <vm/vm_fault.h>
        !            55: #include <mach/kern_return.h>
        !            56: #include <mach/vm_behavior.h>
        !            57: #include <vm/vm_map.h>
        !            58: #include <vm/vm_object.h>
        !            59: #include <vm/vm_page.h>
        !            60: #include <vm/pmap.h>
        !            61: 
        !            62: #include <i386/intel_read_fault.h>
        !            63: 
        !            64: #include <kern/macro_help.h>
        !            65: 
        !            66: /*
        !            67:  *     Expansion of vm_fault for read fault in kernel mode.
        !            68:  *     Must enter the mapping as writable, since the i386
        !            69:  *     (and i860 in i386 compatability mode) ignores write
        !            70:  *     protection in kernel mode.
        !            71:  *
        !            72:  *     Note that this routine can be called for pmap's other
        !            73:  *     than the kernel_pmap, in which case it just enters
        !            74:  *     a read-only mapping.  (See e.g. kernel_trap().)
        !            75:  */
        !            76: kern_return_t
        !            77: intel_read_fault(
        !            78:        vm_map_t        map,
        !            79:        vm_offset_t     vaddr)
        !            80: {
        !            81:        vm_map_version_t        version;        /* Map version for
        !            82:                                                   verification */
        !            83:        vm_object_t             object;         /* Top-level object */
        !            84:        vm_offset_t             offset;         /* Top-level offset */
        !            85:        vm_prot_t               prot;           /* Protection for mapping */
        !            86:        vm_behavior_t           behavior;       /* Expected paging behavior */
        !            87:        vm_offset_t             lo_offset, hi_offset;
        !            88:        vm_page_t               result_page;    /* Result of vm_fault_page */
        !            89:        vm_page_t               top_page;       /* Placeholder page */
        !            90:        boolean_t               wired;          /* Is map region wired? */
        !            91:        kern_return_t           result;
        !            92:        register vm_page_t      m;
        !            93: 
        !            94:     RetryFault:
        !            95: 
        !            96:        /*
        !            97:         *      Find the backing store object and offset into it
        !            98:         *      to begin search.
        !            99:         */
        !           100:        vm_map_lock_read(map);
        !           101:        result = vm_map_lookup_locked(&map, vaddr, VM_PROT_READ, &version,
        !           102:                                      &object, &offset, &prot, &wired,
        !           103:                                      &behavior, &lo_offset, &hi_offset);
        !           104:        vm_map_unlock_read(map);
        !           105: 
        !           106:        if (result != KERN_SUCCESS)
        !           107:            return (result);
        !           108: 
        !           109:        /*
        !           110:         *      Make a reference to this object to prevent its
        !           111:         *      disposal while we are playing with it.
        !           112:         */
        !           113:        assert(object->ref_count > 0);
        !           114:        object->ref_count++;
        !           115:        vm_object_res_reference(object);
        !           116:        vm_object_paging_begin(object);
        !           117: 
        !           118:        result = vm_fault_page(object, offset, VM_PROT_READ, FALSE,
        !           119:                               THREAD_ABORTSAFE,
        !           120:                               lo_offset, hi_offset, behavior,
        !           121:                               &prot, &result_page, &top_page, (int *)0,
        !           122:                               0, map->no_zero_fill, FALSE);
        !           123: 
        !           124:        if (result != VM_FAULT_SUCCESS) {
        !           125:            vm_object_deallocate(object);
        !           126: 
        !           127:            switch (result) {
        !           128:                case VM_FAULT_RETRY:
        !           129:                    goto RetryFault;
        !           130:                case VM_FAULT_INTERRUPTED:
        !           131:                    return (KERN_SUCCESS);
        !           132:                case VM_FAULT_MEMORY_SHORTAGE:
        !           133:                    VM_PAGE_WAIT();
        !           134:                    goto RetryFault;
        !           135:                case VM_FAULT_FICTITIOUS_SHORTAGE:
        !           136:                    vm_page_more_fictitious();
        !           137:                    goto RetryFault;
        !           138:                case VM_FAULT_MEMORY_ERROR:
        !           139:                    return (KERN_MEMORY_ERROR);
        !           140:            }
        !           141:        }
        !           142: 
        !           143:        m = result_page;
        !           144: 
        !           145:        /*
        !           146:         *      How to clean up the result of vm_fault_page.  This
        !           147:         *      happens whether the mapping is entered or not.
        !           148:         */
        !           149: 
        !           150: #define UNLOCK_AND_DEALLOCATE                          \
        !           151:        MACRO_BEGIN                                     \
        !           152:        vm_fault_cleanup(m->object, top_page);          \
        !           153:        vm_object_deallocate(object);                   \
        !           154:        MACRO_END
        !           155: 
        !           156:        /*
        !           157:         *      What to do with the resulting page from vm_fault_page
        !           158:         *      if it doesn't get entered into the physical map:
        !           159:         */
        !           160: 
        !           161: #define RELEASE_PAGE(m)                                        \
        !           162:        MACRO_BEGIN                                     \
        !           163:        PAGE_WAKEUP_DONE(m);                            \
        !           164:        vm_page_lock_queues();                          \
        !           165:        if (!m->active && !m->inactive)                 \
        !           166:                vm_page_activate(m);                    \
        !           167:        vm_page_unlock_queues();                        \
        !           168:        MACRO_END
        !           169: 
        !           170:        /*
        !           171:         *      We must verify that the maps have not changed.
        !           172:         */
        !           173:        vm_object_unlock(m->object);
        !           174:        while (!vm_map_verify(map, &version)) {
        !           175:            vm_object_t         retry_object;
        !           176:            vm_offset_t         retry_offset;
        !           177:            vm_prot_t           retry_prot;
        !           178: 
        !           179:            vm_map_lock_read(map);
        !           180:            result = vm_map_lookup_locked(&map, vaddr, VM_PROT_READ, &version,
        !           181:                                &retry_object, &retry_offset, &retry_prot,
        !           182:                                &wired, &behavior, &lo_offset, &hi_offset);
        !           183:            vm_map_unlock_read(map);
        !           184: 
        !           185:            if (result != KERN_SUCCESS) {
        !           186:                vm_object_lock(m->object);
        !           187:                RELEASE_PAGE(m);
        !           188:                UNLOCK_AND_DEALLOCATE;
        !           189:                return (result);
        !           190:            }
        !           191: 
        !           192:            vm_object_unlock(retry_object);
        !           193: 
        !           194:            if (retry_object != object || retry_offset != offset) {
        !           195:                vm_object_lock(m->object);
        !           196:                RELEASE_PAGE(m);
        !           197:                UNLOCK_AND_DEALLOCATE;
        !           198:                goto RetryFault;
        !           199:            }
        !           200:        }
        !           201: 
        !           202:        /*
        !           203:         *      Put the page in the physical map.
        !           204:         */
        !           205:        PMAP_ENTER(map->pmap, vaddr, m, VM_PROT_READ, wired);
        !           206: 
        !           207:        vm_object_lock(m->object);
        !           208:        vm_page_lock_queues();
        !           209:        if (!m->active && !m->inactive)
        !           210:                vm_page_activate(m);
        !           211:        m->reference = TRUE;
        !           212:        vm_page_unlock_queues();
        !           213: 
        !           214:        vm_map_verify_done(map, &version);
        !           215:        PAGE_WAKEUP_DONE(m);
        !           216: 
        !           217:        UNLOCK_AND_DEALLOCATE;
        !           218: 
        !           219: #undef UNLOCK_AND_DEALLOCATE
        !           220: #undef RELEASE_PAGE
        !           221: 
        !           222:        return (KERN_SUCCESS);
        !           223: }
        !           224: 

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