osfmk/mach/vm_prot.h

   1 /*
   2  * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
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  10  * may not be used to create, or enable the creation or redistribution of,
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  13  * terms of an Apple operating system software license agreement.
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  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
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  28 /*
  29  * @OSF_COPYRIGHT@
  30  */
  31 /*
  32  * Mach Operating System
  33  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  34  * All Rights Reserved.
  35  *
  36  * Permission to use, copy, modify and distribute this software and its
  37  * documentation is hereby granted, provided that both the copyright
  38  * notice and this permission notice appear in all copies of the
  39  * software, derivative works or modified versions, and any portions
  40  * thereof, and that both notices appear in supporting documentation.
  41  *
  42  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  43  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  44  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  45  *
  46  * Carnegie Mellon requests users of this software to return to
  47  *
  48  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  49  *  School of Computer Science
  50  *  Carnegie Mellon University
  51  *  Pittsburgh PA 15213-3890
  52  *
  53  * any improvements or extensions that they make and grant Carnegie Mellon
  54  * the rights to redistribute these changes.
  55  */
  56 /*
  57  */
  58 /*
  59  *      File:   mach/vm_prot.h
  60  *      Author: Avadis Tevanian, Jr., Michael Wayne Young
  61  *
  62  *      Virtual memory protection definitions.
  63  *
  64  */
  65
  66 #ifndef _MACH_VM_PROT_H_
  67 #define _MACH_VM_PROT_H_
  68
  69 /*
  70  *      Types defined:
  71  *
  72  *      vm_prot_t               VM protection values.
  73  */
  74
  75 typedef int             vm_prot_t;
  76
  77 /*
  78  *      Protection values, defined as bits within the vm_prot_t type
  79  */
  80
  81 #define VM_PROT_NONE    ((vm_prot_t) 0x00)
  82
  83 #define VM_PROT_READ    ((vm_prot_t) 0x01)      /* read permission */
  84 #define VM_PROT_WRITE   ((vm_prot_t) 0x02)      /* write permission */
  85 #define VM_PROT_EXECUTE ((vm_prot_t) 0x04)      /* execute permission */
  86
  87 /*
  88  *      The default protection for newly-created virtual memory
  89  */
  90
  91 #define VM_PROT_DEFAULT (VM_PROT_READ|VM_PROT_WRITE)
  92
  93 /*
  94  *      The maximum privileges possible, for parameter checking.
  95  */
  96
  97 #define VM_PROT_ALL     (VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE)
  98
  99 /*
 100  *      An invalid protection value.
 101  *      Used only by memory_object_lock_request to indicate no change
 102  *      to page locks.  Using -1 here is a bad idea because it
 103  *      looks like VM_PROT_ALL and then some.
 104  */
 105
 106 #define VM_PROT_NO_CHANGE       ((vm_prot_t) 0x08)
 107
 108 /*
 109  *      When a caller finds that he cannot obtain write permission on a
 110  *      mapped entry, the following flag can be used.  The entry will
 111  *      be made "needs copy" effectively copying the object (using COW),
 112  *      and write permission will be added to the maximum protections
 113  *      for the associated entry.
 114  */
 115
 116 #define VM_PROT_COPY            ((vm_prot_t) 0x10)
 117
 118
 119 /*
 120  *      Another invalid protection value.
 121  *      Used only by memory_object_data_request upon an object
 122  *      which has specified a copy_call copy strategy. It is used
 123  *      when the kernel wants a page belonging to a copy of the
 124  *      object, and is only asking the object as a result of
 125  *      following a shadow chain. This solves the race between pages
 126  *      being pushed up by the memory manager and the kernel
 127  *      walking down the shadow chain.
 128  */
 129
 130 #define VM_PROT_WANTS_COPY      ((vm_prot_t) 0x10)
 131
 132 #ifdef PRIVATE
 133 /*
 134  *      The caller wants this memory region treated as if it had a valid
 135  *      code signature.
 136  */
 137
 138 #define VM_PROT_TRUSTED         ((vm_prot_t) 0x20)
 139 #endif /* PRIVATE */
 140
 141 /*
 142  *      Another invalid protection value.
 143  *      Indicates that the other protection bits are to be applied as a mask
 144  *      against the actual protection bits of the map entry.
 145  */
 146 #define VM_PROT_IS_MASK         ((vm_prot_t) 0x40)
 147
 148 /*
 149  * Another invalid protection value to support execute-only protection.
 150  * VM_PROT_STRIP_READ is a special marker that tells mprotect to not
 151  * set VM_PROT_READ. We have to do it this way because existing code
 152  * expects the system to set VM_PROT_READ if VM_PROT_EXECUTE is set.
 153  * VM_PROT_EXECUTE_ONLY is just a convenience value to indicate that
 154  * the memory should be executable and explicitly not readable. It will
 155  * be ignored on platforms that do not support this type of protection.
 156  */
 157 #define VM_PROT_STRIP_READ              ((vm_prot_t) 0x80)
 158 #define VM_PROT_EXECUTE_ONLY    (VM_PROT_EXECUTE|VM_PROT_STRIP_READ)
 159
 160 #endif  /* _MACH_VM_PROT_H_ */