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,
30                  uint32_t literal_offset,
31                  uint32_t patch_offset,
32                  uint32_t target_offset) OVERRIDE;
33   void PatchPcRelativeReference(std::vector<uint8_t>* code,
34                                 const LinkerPatch& patch,
35                                 uint32_t patch_offset,
36                                 uint32_t target_offset) OVERRIDE;
37 
38  private:
39   static std::vector<uint8_t> CompileThunkCode();
40 
41   void SetInsn32(std::vector<uint8_t>* code, uint32_t offset, uint32_t value);
42   static uint32_t GetInsn32(ArrayRef<const uint8_t> code, uint32_t offset);
43 
44   template <typename Vector>
45   static uint32_t GetInsn32(Vector* code, uint32_t offset);
46 
47   // PC displacement from patch location; Thumb2 PC is always at instruction address + 4.
48   static constexpr int32_t kPcDisplacement = 4;
49 
50   // Maximum positive and negative displacement measured from the patch location.
51   // (Signed 25 bit displacement with the last bit 0 has range [-2^24, 2^24-2] measured from
52   // the Thumb2 PC pointing right after the BL, i.e. 4 bytes later than the patch location.)
53   static constexpr uint32_t kMaxPositiveDisplacement = (1u << 24) - 2 + kPcDisplacement;
54   static constexpr uint32_t kMaxNegativeDisplacement = (1u << 24) - kPcDisplacement;
55 
56   DISALLOW_COPY_AND_ASSIGN(Thumb2RelativePatcher);
57 };
58 
59 }  // namespace linker
60 }  // namespace art
61 
62 #endif  // ART_COMPILER_LINKER_ARM_RELATIVE_PATCHER_THUMB2_H_
63