runtime/objc-rtp.h

   1 /*
   2  * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 2004 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26   objc-rtp.h
  27   Copyright 2004, Apple Computer, Inc.
  28   Author: Jim Laskey
  29
  30   Layout of the "objc runtime pages", an fixed area
  31   in high memory that can be reached via an absolute branch.
  32   Basic idea is that, on ppc, a single "bla" instruction
  33   (branch & link to absolute address)
  34   can be issued by the compiler to get to high-value routines
  35   in the runtime, including the basic messenger and to the
  36   assignment helper intrinsics issued under -fobjc-gc.
  37   The implementation of the intrinsics is optimized based
  38   on whether the application (process) is running with GC enabled
  39   or not.
  40 */
  41
  42 #ifndef _OBJC_RTP_H_
  43 #define _OBJC_RTP_H_
  44
  45 /*********************************************************************
  46   Layout of the runtime page.
  47
  48   Some of these values must NEVER BE CHANGED, including:
  49   kRTPagesLo
  50   kRTPagesHi
  51   kRTPagesMaxSize
  52   kRTSize_objc_msgSend
  53   kRTSize_objc_assign_ivar
  54   kRTAddress_objc_msgSend          ppc 0xfffeff00
  55   kRTAddress_objc_assign_ivar      ppc 0xfffefec0
  56
  57 *********************************************************************/
  58
  59 #undef OBJC_SIZE_T
  60 #undef OBJC_INTPTR_T
  61 #undef OBJC_UINTPTR_T
  62
  63 #ifdef OBJC_ASM
  64 #define OBJC_SIZE_T(x) (x)
  65 #define OBJC_INTPTR_T(x) (x)
  66 #define OBJC_UINTPTR_T(x) (x)
  67 #else
  68 #define OBJC_SIZE_T(x) ((size_t)(x))
  69 #define OBJC_INTPTR_T(x) ((intptr_t)(x))
  70 #define OBJC_UINTPTR_T(x) ((uintptr_t)(x))
  71 #endif
  72
  73 // Size of RTP area, in bytes (0x1000 = 4k bytes = 1 page)
  74 #define kRTPagesMaxSize  OBJC_SIZE_T(4 * 0x1000)  // size reserved for runtime
  75 #define kRTPagesSize     OBJC_SIZE_T(1 * 0x1000)  // size actually used
  76
  77 // Address of RTP area: [kRTPagesLo..kRTPagesHi)
  78 // These are defined in negative numbers to reflect an offset from the highest address,
  79 // which is what the ppc "bla" instruction is defined to do with "negative" addresses.
  80 // This definition will establish the correct entry points for 64-bit if this mechanism
  81 // is adopted for that architecture as well.
  82 #if defined(__ppc__)
  83 #   define kRTPagesLo    OBJC_UINTPTR_T(-20 * 0x1000) // ppc 0xfffec000
  84 #elif defined(__i386__)
  85 #   define kRTPagesLo    OBJC_UINTPTR_T(-24 * 0x1000) // i386 0xfffe8000
  86 #else
  87     #error unknown architecture
  88 #endif
  89 #define kRTPagesHi       OBJC_UINTPTR_T(kRTPagesLo + kRTPagesMaxSize) // ppc 0xffff0000
  90
  91 // Sizes reserved for functions in the RTP area, in bytes
  92 #define kRTSize_objc_msgSend           OBJC_SIZE_T(0x0100)
  93 #define kRTSize_objc_assign_ivar       OBJC_SIZE_T(0x0040)
  94 #define kRTSize_objc_assign_global     OBJC_SIZE_T(0x0010)
  95 #define kRTSize_objc_assign_strongCast OBJC_SIZE_T(0x0010)
  96
  97 // Absolute address of functions in the RTP area
  98 // These count backwards from the hi end of the RTP area.
  99 // New additions are added to the low side.
 100 #define kRTAddress_objc_msgSend           OBJC_UINTPTR_T(kRTPagesHi - kRTSize_objc_msgSend) // ppc 0xfffeff00
 101 #define kRTAddress_objc_assign_ivar       OBJC_UINTPTR_T(kRTAddress_objc_msgSend - kRTSize_objc_assign_ivar) // ppc 0xfffefec0
 102 #define kRTAddress_objc_assign_global     OBJC_UINTPTR_T(kRTAddress_objc_assign_ivar - kRTSize_objc_assign_global) // ppc 0xfffefeb0
 103 #define kRTAddress_objc_assign_strongCast OBJC_UINTPTR_T(kRTAddress_objc_assign_global - kRTSize_objc_assign_strongCast) // ppc 0xfffefea0
 104
 105 // Sizes reserved for data in the RTP area, in bytes
 106 #define kRTSize_ignoredSelector   OBJC_SIZE_T(19) // 1+strlen("<ignored selector>")
 107
 108 // Absolute address of data in the RTP area
 109 // These count forwards from the lo end of the RTP area.
 110 // These are not locked down and can be moved if necessary.
 111 #define kRTAddress_ignoredSelector OBJC_UINTPTR_T(kRTPagesHi-kRTPagesSize)
 112
 113 #define kIgnore kRTAddress_ignoredSelector  // ppc 0xfffef000
 114
 115 /*********************************************************************
 116   End of runtime page layout.
 117 *********************************************************************/
 118
 119 #endif