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1 /* |
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2 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved. |
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3 * Copyright (c) 2016 SAP SE. All rights reserved. |
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4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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5 * |
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6 * This code is free software; you can redistribute it and/or modify it |
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7 * under the terms of the GNU General Public License version 2 only, as |
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8 * published by the Free Software Foundation. |
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9 * |
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10 * This code is distributed in the hope that it will be useful, but WITHOUT |
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11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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13 * version 2 for more details (a copy is included in the LICENSE file that |
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14 * accompanied this code). |
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15 * |
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16 * You should have received a copy of the GNU General Public License version |
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17 * 2 along with this work; if not, write to the Free Software Foundation, |
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18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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19 * |
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20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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21 * or visit www.oracle.com if you need additional information or have any |
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22 * questions. |
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23 * |
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24 */ |
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25 |
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26 #ifndef CPU_S390_VM_RELOCINFO_S390_HPP |
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27 #define CPU_S390_VM_RELOCINFO_S390_HPP |
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28 |
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29 //---------------------------- |
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30 // relocInfo layout |
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31 //---------------------------- |
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32 |
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33 // This description should be contained in code/relocInfo.hpp |
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34 // but was put here to minimize shared code diffs. |
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35 |
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36 // Relocation information for a nmethod is stored in compressed |
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37 // form in an array of element type short int (16 bits). |
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38 // Each array element constitutes one relocInfo record. |
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39 // The layout of one such record is described here. |
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40 |
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41 // +------------+---+---+------------------------------+ |
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42 // | type | fmt | offset/offset_unit | |
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43 // +------------+---+---+------------------------------+ |
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44 // |
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45 // |<-- value_width (16) ----------------------------->| |
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46 // |<type_width>|<-- nontype_width (12) -------------->| |
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47 // (4) |
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48 // | |<--+-->|<-- offset_width (10) ------->| |
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49 // / \ |
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50 // / (2) \ |
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51 // /<--format->\ |
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52 // | width | |
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53 |
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54 |
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55 // only for type == data_prefix_tag: |
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56 // +------------+---+---+------------------------------+ |
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57 // | type | | data | |
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58 // +------------+---+---+------------------------------+ |
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59 // | 15 |<->|<-- datalen_width (11) ---------->| |
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60 // | |
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61 // +--datalen_tag (1) |
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62 |
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63 // relocType |
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64 // The type field holds a value of relocType (which is |
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65 // an enum of all possible relocation types). Currently, |
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66 // there are 16 distinct relocation types, requiring |
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67 // type_width to be (at least) 4. |
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68 // relocFormat |
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69 // The format field holds a value of relocFormat (which is |
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70 // an enum of all possible relocation formats). Currently, |
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71 // there are 4 distinct relocation formats, requiring |
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72 // format_width to be (at least) 2. |
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73 // offset |
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74 // Each relocInfo is related to one specific address in the CodeBlob. |
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75 // The address always points to the first byte of the target instruction. |
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76 // It does NOT refer directly to the relocation subfield or embedded constant. |
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77 // offset contains the distance of this relocInfo from the previous one. |
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78 // offset is scaled by offset_unit (the platform-specific instruction |
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79 // alignment requirement) to maximize the encodable distance. |
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80 // To obtain the absolute address in the CodeBlob the relocInfo is |
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81 // related to, you have to iterate over all relocInfos from the |
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82 // beginning, and then use RelocIterator::addr() to get the address. |
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83 |
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84 // relocType == data_prefix_tag |
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85 // These are relocInfo records containing inline data that belongs to |
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86 // the next non-data relocInfo record. Usage of that inline data is |
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87 // specific and private to that relocInfo record. |
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88 // For details refer to code/relocInfo.hpp |
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89 |
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90 |
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91 // machine-dependent parts of class relocInfo |
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92 private: |
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93 enum { |
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94 // Instructions are HW (2-byte) aligned on z/Architecture. |
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95 offset_unit = 2, |
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96 |
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97 // Encodes Assembler::disp32_operand vs. Assembler::imm64_operand. |
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98 // (Assembler::call32_operand is used on call instructions only.) |
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99 format_width = 2 |
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100 }; |
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101 |
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102 public: |
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103 |
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104 enum relocFormat { |
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105 no_format = 0, |
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106 uncompressed_format = 0, // Relocation is for a regular oop. |
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107 compressed_format = 1, // Relocation is for a narrow (compressed) oop or klass. |
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108 // Similar to relocInfo::narrow_oop_in_const. |
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109 pcrel_addr_format = 2, // Relocation is for the target LOCATION of a pc-relative instruction. |
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110 pcrel_data_format = 3 // Relocation is for the target data of a pc-relative instruction. |
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111 }; |
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112 |
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113 // Store the new target address into an oop_Relocation cell, if any. |
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114 // Return indication if update happened. |
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115 static bool update_oop_pool(address begin, address end, address newTarget, CodeBlob* cb); |
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116 |
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117 #endif // CPU_S390_VM_RELOCINFO_S390_HPP |