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_COMPILER_LINKER_RELATIVE_PATCHER_H_ 18 #define ART_COMPILER_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 32 namespace debug { 33 struct MethodDebugInfo; 34 } // namespace debug 35 36 namespace linker { 37 38 class LinkerPatch; 39 class OutputStream; 40 41 /** 42 * @class RelativePatcherTargetProvider 43 * @brief Interface for providing method offsets for relative call targets. 44 */ 45 class RelativePatcherTargetProvider { 46 public: 47 /** 48 * Find the offset of the target method of a relative call if known. 49 * 50 * The process of assigning target method offsets includes calls to the relative patcher's 51 * ReserveSpace() which in turn can use FindMethodOffset() to determine if a method already 52 * has an offset assigned and, if so, what's that offset. If the offset has not yet been 53 * assigned or if it's too far for the particular architecture's relative call, 54 * ReserveSpace() may need to allocate space for a special dispatch thunk. 55 * 56 * @param ref the target method of the relative call. 57 * @return true in the first element of the pair if the method was found, false otherwise; 58 * if found, the second element specifies the offset. 59 */ 60 virtual std::pair<bool, uint32_t> FindMethodOffset(MethodReference ref) = 0; 61 62 protected: ~RelativePatcherTargetProvider()63 virtual ~RelativePatcherTargetProvider() { } 64 }; 65 66 /** 67 * @class RelativePatcher 68 * @brief Interface for architecture-specific link-time patching of PC-relative references. 69 */ 70 class RelativePatcher { 71 public: 72 static std::unique_ptr<RelativePatcher> Create( 73 InstructionSet instruction_set, const InstructionSetFeatures* features, 74 RelativePatcherTargetProvider* provider); 75 ~RelativePatcher()76 virtual ~RelativePatcher() { } 77 CodeAlignmentSize()78 uint32_t CodeAlignmentSize() const { 79 return size_code_alignment_; 80 } 81 RelativeCallThunksSize()82 uint32_t RelativeCallThunksSize() const { 83 return size_relative_call_thunks_; 84 } 85 MiscThunksSize()86 uint32_t MiscThunksSize() const { 87 return size_misc_thunks_; 88 } 89 90 // Reserve space for thunks if needed before a method, return adjusted offset. 91 virtual uint32_t ReserveSpace(uint32_t offset, 92 const CompiledMethod* compiled_method, 93 MethodReference method_ref) = 0; 94 95 // Reserve space for thunks if needed after the last method, return adjusted offset. 96 // The caller may use this method to preemptively force thunk space reservation and 97 // then resume reservation for more methods. This is useful when there is a gap in 98 // the .text segment, for example when going to the next oat file for multi-image. 99 virtual uint32_t ReserveSpaceEnd(uint32_t offset) = 0; 100 101 // Write relative call thunks if needed, return adjusted offset. Returns 0 on write failure. 102 virtual uint32_t WriteThunks(OutputStream* out, uint32_t offset) = 0; 103 104 // Patch method code. The input displacement is relative to the patched location, 105 // the patcher may need to adjust it if the correct base is different. 106 virtual void PatchCall(std::vector<uint8_t>* code, 107 uint32_t literal_offset, 108 uint32_t patch_offset, 109 uint32_t target_offset) = 0; 110 111 // Patch a reference to a dex cache location. 112 virtual void PatchPcRelativeReference(std::vector<uint8_t>* code, 113 const LinkerPatch& patch, 114 uint32_t patch_offset, 115 uint32_t target_offset) = 0; 116 117 // Patch a branch to a Baker read barrier thunk. 118 virtual void PatchBakerReadBarrierBranch(std::vector<uint8_t>* code, 119 const LinkerPatch& patch, 120 uint32_t patch_offset) = 0; 121 122 virtual std::vector<debug::MethodDebugInfo> GenerateThunkDebugInfo( 123 uint32_t executable_offset) = 0; 124 125 protected: RelativePatcher()126 RelativePatcher() 127 : size_code_alignment_(0u), 128 size_relative_call_thunks_(0u), 129 size_misc_thunks_(0u) { 130 } 131 132 bool WriteCodeAlignment(OutputStream* out, uint32_t aligned_code_delta); 133 bool WriteThunk(OutputStream* out, const ArrayRef<const uint8_t>& thunk); 134 bool WriteMiscThunk(OutputStream* out, const ArrayRef<const uint8_t>& thunk); 135 136 private: 137 uint32_t size_code_alignment_; 138 uint32_t size_relative_call_thunks_; 139 uint32_t size_misc_thunks_; 140 141 DISALLOW_COPY_AND_ASSIGN(RelativePatcher); 142 }; 143 144 } // namespace linker 145 } // namespace art 146 147 #endif // ART_COMPILER_LINKER_RELATIVE_PATCHER_H_ 148