1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ART_DEX2OAT_LINKER_RELATIVE_PATCHER_H_ 18 #define ART_DEX2OAT_LINKER_RELATIVE_PATCHER_H_ 19 20 #include <vector> 21 22 #include "arch/instruction_set.h" 23 #include "arch/instruction_set_features.h" 24 #include "base/array_ref.h" 25 #include "base/macros.h" 26 #include "dex/method_reference.h" 27 28 namespace art { 29 30 class CompiledMethod; 31 class OutputStream; 32 33 namespace debug { 34 struct MethodDebugInfo; 35 } // namespace debug 36 37 namespace linker { 38 39 class LinkerPatch; 40 41 /** 42 * @class RelativePatcherThunkProvider 43 * @brief Interface for providing method offsets for relative call targets. 44 */ 45 class RelativePatcherThunkProvider { 46 public: 47 /** 48 * Get the code and debug name of a thunk needed by the given linker patch. 49 * 50 * @param patch The patch for which we need to retrieve the thunk code. 51 * @param code A variable to receive the code of the thunk. This code must not be empty. 52 * @param debug_name A variable to receive the debug name of the thunk. 53 */ 54 virtual void GetThunkCode(const LinkerPatch& patch, 55 /*out*/ ArrayRef<const uint8_t>* code, 56 /*out*/ std::string* debug_name) = 0; 57 58 protected: ~RelativePatcherThunkProvider()59 virtual ~RelativePatcherThunkProvider() { } 60 }; 61 62 /** 63 * @class RelativePatcherTargetProvider 64 * @brief Interface for providing method offsets for relative call targets. 65 */ 66 class RelativePatcherTargetProvider { 67 public: 68 /** 69 * Find the offset of the target method of a relative call if known. 70 * 71 * The process of assigning target method offsets includes calls to the relative patcher's 72 * ReserveSpace() which in turn can use FindMethodOffset() to determine if a method already 73 * has an offset assigned and, if so, what's that offset. If the offset has not yet been 74 * assigned or if it's too far for the particular architecture's relative call, 75 * ReserveSpace() may need to allocate space for a special dispatch thunk. 76 * 77 * @param ref the target method of the relative call. 78 * @return true in the first element of the pair if the method was found, false otherwise; 79 * if found, the second element specifies the offset. 80 */ 81 virtual std::pair<bool, uint32_t> FindMethodOffset(MethodReference ref) = 0; 82 83 protected: ~RelativePatcherTargetProvider()84 virtual ~RelativePatcherTargetProvider() { } 85 }; 86 87 /** 88 * @class RelativePatcher 89 * @brief Interface for architecture-specific link-time patching of PC-relative references. 90 */ 91 class RelativePatcher { 92 public: 93 static std::unique_ptr<RelativePatcher> Create( 94 InstructionSet instruction_set, 95 const InstructionSetFeatures* features, 96 RelativePatcherThunkProvider* thunk_provider, 97 RelativePatcherTargetProvider* target_provider); 98 ~RelativePatcher()99 virtual ~RelativePatcher() { } 100 CodeAlignmentSize()101 uint32_t CodeAlignmentSize() const { 102 return size_code_alignment_; 103 } 104 RelativeCallThunksSize()105 uint32_t RelativeCallThunksSize() const { 106 return size_relative_call_thunks_; 107 } 108 MiscThunksSize()109 uint32_t MiscThunksSize() const { 110 return size_misc_thunks_; 111 } 112 113 // Reserve space for thunks if needed before a method, return adjusted offset. 114 virtual uint32_t ReserveSpace(uint32_t offset, 115 const CompiledMethod* compiled_method, 116 MethodReference method_ref) = 0; 117 118 // Reserve space for thunks if needed after the last method, return adjusted offset. 119 // The caller may use this method to preemptively force thunk space reservation and 120 // then resume reservation for more methods. This is useful when there is a gap in 121 // the .text segment, for example when going to the next oat file for multi-image. 122 virtual uint32_t ReserveSpaceEnd(uint32_t offset) = 0; 123 124 // Write relative call thunks if needed, return adjusted offset. Returns 0 on write failure. 125 virtual uint32_t WriteThunks(OutputStream* out, uint32_t offset) = 0; 126 127 // Patch method code. The input displacement is relative to the patched location, 128 // the patcher may need to adjust it if the correct base is different. 129 virtual void PatchCall(std::vector<uint8_t>* code, 130 uint32_t literal_offset, 131 uint32_t patch_offset, 132 uint32_t target_offset) = 0; 133 134 // Patch a reference to a dex cache location. 135 virtual void PatchPcRelativeReference(std::vector<uint8_t>* code, 136 const LinkerPatch& patch, 137 uint32_t patch_offset, 138 uint32_t target_offset) = 0; 139 140 // Patch a call to an entrypoint trampoline. 141 virtual void PatchEntrypointCall(std::vector<uint8_t>* code, 142 const LinkerPatch& patch, 143 uint32_t patch_offset) = 0; 144 145 // Patch a branch to a Baker read barrier thunk. 146 virtual void PatchBakerReadBarrierBranch(std::vector<uint8_t>* code, 147 const LinkerPatch& patch, 148 uint32_t patch_offset) = 0; 149 150 virtual std::vector<debug::MethodDebugInfo> GenerateThunkDebugInfo( 151 uint32_t executable_offset) = 0; 152 153 protected: RelativePatcher()154 RelativePatcher() 155 : size_code_alignment_(0u), 156 size_relative_call_thunks_(0u), 157 size_misc_thunks_(0u) { 158 } 159 160 bool WriteCodeAlignment(OutputStream* out, uint32_t aligned_code_delta); 161 bool WriteThunk(OutputStream* out, const ArrayRef<const uint8_t>& thunk); 162 bool WriteMiscThunk(OutputStream* out, const ArrayRef<const uint8_t>& thunk); 163 164 private: 165 uint32_t size_code_alignment_; 166 uint32_t size_relative_call_thunks_; 167 uint32_t size_misc_thunks_; 168 169 DISALLOW_COPY_AND_ASSIGN(RelativePatcher); 170 }; 171 172 } // namespace linker 173 } // namespace art 174 175 #endif // ART_DEX2OAT_LINKER_RELATIVE_PATCHER_H_ 176