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 #include "linker/x86/relative_patcher_x86_base.h" 18 19 namespace art { 20 namespace linker { 21 22 uint32_t X86BaseRelativePatcher::ReserveSpace( 23 uint32_t offset, 24 const CompiledMethod* compiled_method ATTRIBUTE_UNUSED, 25 MethodReference method_ref ATTRIBUTE_UNUSED) { 26 return offset; // No space reserved; no limit on relative call distance. 27 } 28 29 uint32_t X86BaseRelativePatcher::ReserveSpaceEnd(uint32_t offset) { 30 return offset; // No space reserved; no limit on relative call distance. 31 } 32 33 uint32_t X86BaseRelativePatcher::WriteThunks(OutputStream* out ATTRIBUTE_UNUSED, uint32_t offset) { 34 return offset; // No thunks added; no limit on relative call distance. 35 } 36 37 void X86BaseRelativePatcher::PatchCall(std::vector<uint8_t>* code, 38 uint32_t literal_offset, 39 uint32_t patch_offset, 40 uint32_t target_offset) { 41 DCHECK_LE(literal_offset + 4u, code->size()); 42 // Unsigned arithmetic with its well-defined overflow behavior is just fine here. 43 uint32_t displacement = target_offset - patch_offset; 44 displacement -= kPcDisplacement; // The base PC is at the end of the 4-byte patch. 45 46 typedef __attribute__((__aligned__(1))) int32_t unaligned_int32_t; 47 reinterpret_cast<unaligned_int32_t*>(&(*code)[literal_offset])[0] = displacement; 48 } 49 50 } // namespace linker 51 } // namespace art 52
