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Annotation of OSKit-Mach/i386/intel/read_fault.c, revision 1.1

1.1     ! root        1: /* 
        !             2:  * Mach Operating System
        !             3:  * Copyright (c) 1991,1990 Carnegie Mellon University
        !             4:  * All Rights Reserved.
        !             5:  * 
        !             6:  * Permission to use, copy, modify and distribute this software and its
        !             7:  * documentation is hereby granted, provided that both the copyright
        !             8:  * notice and this permission notice appear in all copies of the
        !             9:  * software, derivative works or modified versions, and any portions
        !            10:  * thereof, and that both notices appear in supporting documentation.
        !            11:  * 
        !            12:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
        !            13:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
        !            14:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            15:  * 
        !            16:  * Carnegie Mellon requests users of this software to return to
        !            17:  * 
        !            18:  *  Software Distribution Coordinator  or  [email protected]
        !            19:  *  School of Computer Science
        !            20:  *  Carnegie Mellon University
        !            21:  *  Pittsburgh PA 15213-3890
        !            22:  * 
        !            23:  * any improvements or extensions that they make and grant Carnegie Mellon
        !            24:  * the rights to redistribute these changes.
        !            25:  */
        !            26: 
        !            27: #include <vm/vm_fault.h>
        !            28: #include <mach/kern_return.h>
        !            29: #include <vm/vm_map.h>
        !            30: #include <vm/vm_object.h>
        !            31: #include <vm/vm_page.h>
        !            32: #include <vm/pmap.h>
        !            33: 
        !            34: #include <kern/macro_help.h>
        !            35: 
        !            36: /*
        !            37:  *     Expansion of vm_fault for read fault in kernel mode.
        !            38:  *     Must enter the mapping as writable, since the i386
        !            39:  *     (and i860 in i386 compatability mode) ignores write
        !            40:  *     protection in kernel mode.
        !            41:  */
        !            42: kern_return_t
        !            43: intel_read_fault(map, vaddr)
        !            44:        vm_map_t        map;
        !            45:        vm_offset_t     vaddr;
        !            46: {
        !            47:        vm_map_version_t        version;        /* Map version for
        !            48:                                                   verification */
        !            49:        vm_object_t             object;         /* Top-level object */
        !            50:        vm_offset_t             offset;         /* Top-level offset */
        !            51:        vm_prot_t               prot;           /* Protection for mapping */
        !            52:        vm_page_t               result_page;    /* Result of vm_fault_page */
        !            53:        vm_page_t               top_page;       /* Placeholder page */
        !            54:        boolean_t               wired;          /* Is map region wired? */
        !            55:        boolean_t               su;
        !            56:        kern_return_t           result;
        !            57:        register vm_page_t      m;
        !            58: 
        !            59:     RetryFault:
        !            60: 
        !            61:        /*
        !            62:         *      Find the backing store object and offset into it
        !            63:         *      to begin search.
        !            64:         */
        !            65:        result = vm_map_lookup(&map, vaddr, VM_PROT_READ, &version,
        !            66:                        &object, &offset, &prot, &wired, &su);
        !            67:        if (result != KERN_SUCCESS)
        !            68:            return (result);
        !            69: 
        !            70:        /*
        !            71:         *      Make a reference to this object to prevent its
        !            72:         *      disposal while we are playing with it.
        !            73:         */
        !            74:        assert(object->ref_count > 0);
        !            75:        object->ref_count++;
        !            76:        vm_object_paging_begin(object);
        !            77: 
        !            78:        result = vm_fault_page(object, offset, VM_PROT_READ, FALSE, TRUE,
        !            79:                               &prot, &result_page, &top_page,
        !            80:                               FALSE, (void (*)()) 0);
        !            81: 
        !            82:        if (result != VM_FAULT_SUCCESS) {
        !            83:            vm_object_deallocate(object);
        !            84: 
        !            85:            switch (result) {
        !            86:                case VM_FAULT_RETRY:
        !            87:                    goto RetryFault;
        !            88:                case VM_FAULT_INTERRUPTED:
        !            89:                    return (KERN_SUCCESS);
        !            90:                case VM_FAULT_MEMORY_SHORTAGE:
        !            91:                    VM_PAGE_WAIT((void (*)()) 0);
        !            92:                    goto RetryFault;
        !            93:                case VM_FAULT_FICTITIOUS_SHORTAGE:
        !            94:                    vm_page_more_fictitious();
        !            95:                    goto RetryFault;
        !            96:                case VM_FAULT_MEMORY_ERROR:
        !            97:                    return (KERN_MEMORY_ERROR);
        !            98:            }
        !            99:        }
        !           100: 
        !           101:        m = result_page;
        !           102: 
        !           103:        /*
        !           104:         *      How to clean up the result of vm_fault_page.  This
        !           105:         *      happens whether the mapping is entered or not.
        !           106:         */
        !           107: 
        !           108: #define UNLOCK_AND_DEALLOCATE                          \
        !           109:        MACRO_BEGIN                                     \
        !           110:        vm_fault_cleanup(m->object, top_page);          \
        !           111:        vm_object_deallocate(object);                   \
        !           112:        MACRO_END
        !           113: 
        !           114:        /*
        !           115:         *      What to do with the resulting page from vm_fault_page
        !           116:         *      if it doesn't get entered into the physical map:
        !           117:         */
        !           118: 
        !           119: #define RELEASE_PAGE(m)                                        \
        !           120:        MACRO_BEGIN                                     \
        !           121:        PAGE_WAKEUP_DONE(m);                            \
        !           122:        vm_page_lock_queues();                          \
        !           123:        if (!m->active && !m->inactive)                 \
        !           124:                vm_page_activate(m);                    \
        !           125:        vm_page_unlock_queues();                        \
        !           126:        MACRO_END
        !           127: 
        !           128:        /*
        !           129:         *      We must verify that the maps have not changed.
        !           130:         */
        !           131:        vm_object_unlock(m->object);
        !           132:        while (!vm_map_verify(map, &version)) {
        !           133:            vm_object_t         retry_object;
        !           134:            vm_offset_t         retry_offset;
        !           135:            vm_prot_t           retry_prot;
        !           136: 
        !           137:            result = vm_map_lookup(&map, vaddr, VM_PROT_READ, &version,
        !           138:                                &retry_object, &retry_offset, &retry_prot,
        !           139:                                &wired, &su);
        !           140:            if (result != KERN_SUCCESS) {
        !           141:                vm_object_lock(m->object);
        !           142:                RELEASE_PAGE(m);
        !           143:                UNLOCK_AND_DEALLOCATE;
        !           144:                return (result);
        !           145:            }
        !           146: 
        !           147:            vm_object_unlock(retry_object);
        !           148: 
        !           149:            if (retry_object != object || retry_offset != offset) {
        !           150:                vm_object_lock(m->object);
        !           151:                RELEASE_PAGE(m);
        !           152:                UNLOCK_AND_DEALLOCATE;
        !           153:                goto RetryFault;
        !           154:            }
        !           155:        }
        !           156: 
        !           157:        /*
        !           158:         *      Put the page in the physical map.
        !           159:         */
        !           160:        PMAP_ENTER(map->pmap, vaddr, m, VM_PROT_READ|VM_PROT_WRITE, wired);
        !           161: 
        !           162:        vm_object_lock(m->object);
        !           163:        vm_page_lock_queues();
        !           164:        if (!m->active && !m->inactive)
        !           165:                vm_page_activate(m);
        !           166:        m->reference = TRUE;
        !           167:        vm_page_unlock_queues();
        !           168: 
        !           169:        vm_map_verify_done(map, &version);
        !           170:        PAGE_WAKEUP_DONE(m);
        !           171: 
        !           172:        UNLOCK_AND_DEALLOCATE;
        !           173: 
        !           174: #undef UNLOCK_AND_DEALLOCATE
        !           175: #undef RELEASE_PAGE
        !           176: 
        !           177:        return (KERN_SUCCESS);
        !           178: }

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