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 "method_reference.h" 27 28 namespace art { 29 30 class CompiledMethod; 31 class LinkerPatch; 32 class OutputStream; 33 34 namespace linker { 35 36 /** 37 * @class RelativePatcherTargetProvider 38 * @brief Interface for providing method offsets for relative call targets. 39 */ 40 class RelativePatcherTargetProvider { 41 public: 42 /** 43 * Find the offset of the target method of a relative call if known. 44 * 45 * The process of assigning target method offsets includes calls to the relative patcher's 46 * ReserveSpace() which in turn can use FindMethodOffset() to determine if a method already 47 * has an offset assigned and, if so, what's that offset. If the offset has not yet been 48 * assigned or if it's too far for the particular architecture's relative call, 49 * ReserveSpace() may need to allocate space for a special dispatch thunk. 50 * 51 * @param ref the target method of the relative call. 52 * @return true in the first element of the pair if the method was found, false otherwise; 53 * if found, the second element specifies the offset. 54 */ 55 virtual std::pair<bool, uint32_t> FindMethodOffset(MethodReference ref) = 0; 56 57 protected: 58 virtual ~RelativePatcherTargetProvider() { } 59 }; 60 61 /** 62 * @class RelativePatcher 63 * @brief Interface for architecture-specific link-time patching of PC-relative references. 64 */ 65 class RelativePatcher { 66 public: 67 static std::unique_ptr<RelativePatcher> Create( 68 InstructionSet instruction_set, const InstructionSetFeatures* features, 69 RelativePatcherTargetProvider* provider); 70 71 virtual ~RelativePatcher() { } 72 73 uint32_t CodeAlignmentSize() const { 74 return size_code_alignment_; 75 } 76 77 uint32_t RelativeCallThunksSize() const { 78 return size_relative_call_thunks_; 79 } 80 81 uint32_t MiscThunksSize() const { 82 return size_misc_thunks_; 83 } 84 85 // Reserve space for thunks if needed before a method, return adjusted offset. 86 virtual uint32_t ReserveSpace(uint32_t offset, 87 const CompiledMethod* compiled_method, 88 MethodReference method_ref) = 0; 89 90 // Reserve space for thunks if needed after the last method, return adjusted offset. 91 // The caller may use this method to preemptively force thunk space reservation and 92 // then resume reservation for more methods. This is useful when there is a gap in 93 // the .text segment, for example when going to the next oat file for multi-image. 94 virtual uint32_t ReserveSpaceEnd(uint32_t offset) = 0; 95 96 // Write relative call thunks if needed, return adjusted offset. Returns 0 on write failure. 97 virtual uint32_t WriteThunks(OutputStream* out, uint32_t offset) = 0; 98 99 // Patch method code. The input displacement is relative to the patched location, 100 // the patcher may need to adjust it if the correct base is different. 101 virtual void PatchCall(std::vector<uint8_t>* code, 102 uint32_t literal_offset, 103 uint32_t patch_offset, 104 uint32_t target_offset) = 0; 105 106 // Patch a reference to a dex cache location. 107 virtual void PatchPcRelativeReference(std::vector<uint8_t>* code, 108 const LinkerPatch& patch, 109 uint32_t patch_offset, 110 uint32_t target_offset) = 0; 111 112 // Patch a branch to a Baker read barrier thunk. 113 virtual void PatchBakerReadBarrierBranch(std::vector<uint8_t>* code, 114 const LinkerPatch& patch, 115 uint32_t patch_offset) = 0; 116 117 protected: 118 RelativePatcher() 119 : size_code_alignment_(0u), 120 size_relative_call_thunks_(0u), 121 size_misc_thunks_(0u) { 122 } 123 124 bool WriteCodeAlignment(OutputStream* out, uint32_t aligned_code_delta); 125 bool WriteThunk(OutputStream* out, const ArrayRef<const uint8_t>& thunk); 126 bool WriteMiscThunk(OutputStream* out, const ArrayRef<const uint8_t>& thunk); 127 128 private: 129 uint32_t size_code_alignment_; 130 uint32_t size_relative_call_thunks_; 131 uint32_t size_misc_thunks_; 132 133 DISALLOW_COPY_AND_ASSIGN(RelativePatcher); 134 }; 135 136 } // namespace linker 137 } // namespace art 138 139 #endif // ART_COMPILER_LINKER_RELATIVE_PATCHER_H_ 140
