runtime/objc-rtp.h

   1 /*
   2  * Copyright (c) 2004-2006 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*
  24   Layout of the "objc runtime pages", an fixed area
  25   in high memory that can be reached via an absolute branch.
  26   Basic idea is that, on ppc, a single "bla" instruction
  27   (branch & link to absolute address)
  28   can be issued by the compiler to get to high-value routines
  29   in the runtime, including the basic messenger and to the
  30   assignment helper intrinsics issued under -fobjc-gc.
  31   The implementation of the intrinsics is optimized based
  32   on whether the application (process) is running with GC enabled
  33   or not.
  34 */
  35
  36 #ifndef _OBJC_RTP_H_
  37 #define _OBJC_RTP_H_
  38
  39 /*********************************************************************
  40   Layout of the runtime page.
  41
  42   Some of these values must NEVER BE CHANGED, including:
  43   kRTPagesLo
  44   kRTPagesHi
  45   kRTPagesMaxSize
  46   kRTSize_objc_msgSend
  47   kRTSize_objc_assign_ivar
  48   kRTAddress_objc_msgSend          ppc 0xfffeff00
  49   kRTAddress_objc_assign_ivar      ppc 0xfffefec0
  50
  51 *********************************************************************/
  52
  53 #undef OBJC_SIZE_T
  54 #undef OBJC_INTPTR_T
  55 #undef OBJC_UINTPTR_T
  56
  57 #ifdef OBJC_ASM
  58 #define OBJC_SIZE_T(x) (x)
  59 #define OBJC_INTPTR_T(x) (x)
  60 #define OBJC_UINTPTR_T(x) (x)
  61 #else
  62 #define OBJC_SIZE_T(x) ((size_t)(x))
  63 #define OBJC_INTPTR_T(x) ((intptr_t)(x))
  64 #define OBJC_UINTPTR_T(x) ((uintptr_t)(x))
  65 #endif
  66
  67 // Size of RTP area, in bytes (0x1000 = 4k bytes = 1 page)
  68 #define kRTPagesMaxSize  OBJC_SIZE_T(4 * 0x1000)  // size reserved for runtime
  69 #define kRTPagesSize     OBJC_SIZE_T(1 * 0x1000)  // size actually used
  70
  71 // Address of RTP area: [kRTPagesLo..kRTPagesHi)
  72 // These are defined in negative numbers to reflect an offset from the highest address,
  73 // which is what the ppc "bla" instruction is defined to do with "negative" addresses.
  74 // This definition will establish the correct entry points for 64-bit if this mechanism
  75 // is adopted for that architecture as well.
  76 #if defined(__ppc__)  ||  defined(__ppc64__)
  77 #   define kRTPagesLo    OBJC_UINTPTR_T(-20 * 0x1000) // ppc 0xfffec000
  78 #elif defined(__i386__)
  79 #   define kRTPagesLo    OBJC_UINTPTR_T(-24 * 0x1000) // i386 0xfffe8000
  80 #elif defined(__x86_64__)
  81 #   define kRTPagesLo    OBJC_UINTPTR_T(-24 * 0x1000) // x86_64 0xfffffffffffe8000
  82 #elif defined(__arm__)  ||  defined(TARGET_OS_WIN32)
  83 #   define kRTPagesLo    OBJC_UINTPTR_T(0)
  84 #else
  85     #error unknown architecture
  86 #endif
  87 #define kRTPagesHi       OBJC_UINTPTR_T(kRTPagesLo + kRTPagesMaxSize) // ppc 0xffff0000
  88
  89 // Sizes reserved for functions in the RTP area, in bytes
  90 #define kRTSize_objc_msgSend           OBJC_SIZE_T(0x0100)
  91 #define kRTSize_objc_assign_ivar       OBJC_SIZE_T(0x0040)
  92 #define kRTSize_objc_assign_global     OBJC_SIZE_T(0x0010)
  93 #define kRTSize_objc_assign_strongCast OBJC_SIZE_T(0x0010)
  94
  95 // Absolute address of functions in the RTP area
  96 // These count backwards from the hi end of the RTP area.
  97 // New additions are added to the low side.
  98 #define kRTAddress_objc_msgSend           OBJC_UINTPTR_T(kRTPagesHi - kRTSize_objc_msgSend) // ppc 0xfffeff00
  99 #define kRTAddress_objc_assign_ivar       OBJC_UINTPTR_T(kRTAddress_objc_msgSend - kRTSize_objc_assign_ivar) // ppc 0xfffefec0
 100 #define kRTAddress_objc_assign_global     OBJC_UINTPTR_T(kRTAddress_objc_assign_ivar - kRTSize_objc_assign_global) // ppc 0xfffefeb0
 101 #define kRTAddress_objc_assign_strongCast OBJC_UINTPTR_T(kRTAddress_objc_assign_global - kRTSize_objc_assign_strongCast) // ppc 0xfffefea0
 102
 103 // Sizes reserved for data in the RTP area, in bytes
 104 #define kRTSize_zero              OBJC_SIZE_T(16) // 16 zero bytes
 105 #define kRTSize_ignoredSelector   OBJC_SIZE_T(19) // 1+strlen("<ignored selector>")
 106
 107 // Absolute address of data in the RTP area
 108 // These count forwards from the lo end of the RTP area.
 109 // These are not locked down and can be moved if necessary.
 110 #define kRTAddress_zero OBJC_UINTPTR_T(kRTPagesHi-kRTPagesSize)
 111 #define kRTAddress_ignoredSelector OBJC_UINTPTR_T(kRTAddress_zero+kRTSize_zero)
 112
 113 #define kIgnore kRTAddress_ignoredSelector  // ppc 0xfffef000
 114
 115 /*********************************************************************
 116   End of runtime page layout.
 117 *********************************************************************/
 118
 119 #endif