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_ARM_RELATIVE_PATCHER_THUMB2_H_
18 #define ART_COMPILER_LINKER_ARM_RELATIVE_PATCHER_THUMB2_H_
19 
20 #include "linker/arm/relative_patcher_arm_base.h"
21 
22 namespace art {
23 namespace linker {
24 
25 class Thumb2RelativePatcher FINAL : public ArmBaseRelativePatcher {
26  public:
27   explicit Thumb2RelativePatcher(RelativePatcherTargetProvider* provider);
28 
29   void PatchCall(std::vector<uint8_t>* code, uint32_t literal_offset,
30                  uint32_t patch_offset, uint32_t target_offset) OVERRIDE;
31   void PatchDexCacheReference(std::vector<uint8_t>* code, const LinkerPatch& patch,
32                               uint32_t patch_offset, uint32_t target_offset) OVERRIDE;
33 
34  private:
35   static std::vector<uint8_t> CompileThunkCode();
36 
37   void SetInsn32(std::vector<uint8_t>* code, uint32_t offset, uint32_t value);
38   static uint32_t GetInsn32(ArrayRef<const uint8_t> code, uint32_t offset);
39 
40   template <typename Alloc>
41   static uint32_t GetInsn32(std::vector<uint8_t, Alloc>* code, uint32_t offset);
42 
43   // PC displacement from patch location; Thumb2 PC is always at instruction address + 4.
44   static constexpr int32_t kPcDisplacement = 4;
45 
46   // Maximum positive and negative displacement measured from the patch location.
47   // (Signed 25 bit displacement with the last bit 0 has range [-2^24, 2^24-2] measured from
48   // the Thumb2 PC pointing right after the BL, i.e. 4 bytes later than the patch location.)
49   static constexpr uint32_t kMaxPositiveDisplacement = (1u << 24) - 2 + kPcDisplacement;
50   static constexpr uint32_t kMaxNegativeDisplacement = (1u << 24) - kPcDisplacement;
51 
52   DISALLOW_COPY_AND_ASSIGN(Thumb2RelativePatcher);
53 };
54 
55 }  // namespace linker
56 }  // namespace art
57 
58 #endif  // ART_COMPILER_LINKER_ARM_RELATIVE_PATCHER_THUMB2_H_
59