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1 /*
2  * Copyright (C) 2016 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/mips/relative_patcher_mips.h"
18 
19 #include "compiled_method.h"
20 #include "debug/method_debug_info.h"
21 #include "linker/linker_patch.h"
22 
23 namespace art {
24 namespace linker {
25 
ReserveSpace(uint32_t offset,const CompiledMethod * compiled_method ATTRIBUTE_UNUSED,MethodReference method_ref ATTRIBUTE_UNUSED)26 uint32_t MipsRelativePatcher::ReserveSpace(
27     uint32_t offset,
28     const CompiledMethod* compiled_method ATTRIBUTE_UNUSED,
29     MethodReference method_ref ATTRIBUTE_UNUSED) {
30   return offset;  // No space reserved; no limit on relative call distance.
31 }
32 
ReserveSpaceEnd(uint32_t offset)33 uint32_t MipsRelativePatcher::ReserveSpaceEnd(uint32_t offset) {
34   return offset;  // No space reserved; no limit on relative call distance.
35 }
36 
WriteThunks(OutputStream * out ATTRIBUTE_UNUSED,uint32_t offset)37 uint32_t MipsRelativePatcher::WriteThunks(OutputStream* out ATTRIBUTE_UNUSED, uint32_t offset) {
38   return offset;  // No thunks added; no limit on relative call distance.
39 }
40 
PatchCall(std::vector<uint8_t> * code ATTRIBUTE_UNUSED,uint32_t literal_offset ATTRIBUTE_UNUSED,uint32_t patch_offset ATTRIBUTE_UNUSED,uint32_t target_offset ATTRIBUTE_UNUSED)41 void MipsRelativePatcher::PatchCall(std::vector<uint8_t>* code ATTRIBUTE_UNUSED,
42                                     uint32_t literal_offset ATTRIBUTE_UNUSED,
43                                     uint32_t patch_offset ATTRIBUTE_UNUSED,
44                                     uint32_t target_offset ATTRIBUTE_UNUSED) {
45   UNIMPLEMENTED(FATAL) << "PatchCall unimplemented on MIPS";
46 }
47 
PatchPcRelativeReference(std::vector<uint8_t> * code,const LinkerPatch & patch,uint32_t patch_offset,uint32_t target_offset)48 void MipsRelativePatcher::PatchPcRelativeReference(std::vector<uint8_t>* code,
49                                                    const LinkerPatch& patch,
50                                                    uint32_t patch_offset,
51                                                    uint32_t target_offset) {
52   uint32_t anchor_literal_offset = patch.PcInsnOffset();
53   uint32_t literal_offset = patch.LiteralOffset();
54   bool high_patch = ((*code)[literal_offset + 0] == 0x34) && ((*code)[literal_offset + 1] == 0x12);
55 
56   // Perform basic sanity checks.
57   if (high_patch) {
58     if (is_r6) {
59       // auipc reg, offset_high
60       DCHECK_EQ(((*code)[literal_offset + 2] & 0x1F), 0x1E);
61       DCHECK_EQ(((*code)[literal_offset + 3] & 0xFC), 0xEC);
62     } else {
63       // lui reg, offset_high
64       DCHECK_EQ(((*code)[literal_offset + 2] & 0xE0), 0x00);
65       DCHECK_EQ((*code)[literal_offset + 3], 0x3C);
66     }
67   } else {
68     // instr reg(s), offset_low
69     CHECK_EQ((*code)[literal_offset + 0], 0x78);
70     CHECK_EQ((*code)[literal_offset + 1], 0x56);
71   }
72 
73   // Apply patch.
74   uint32_t anchor_offset = patch_offset - literal_offset + anchor_literal_offset;
75   uint32_t diff = target_offset - anchor_offset;
76   diff += (diff & 0x8000) << 1;  // Account for sign extension in "instr reg(s), offset_low".
77 
78   if (high_patch) {
79     // lui reg, offset_high / auipc reg, offset_high
80     (*code)[literal_offset + 0] = static_cast<uint8_t>(diff >> 16);
81     (*code)[literal_offset + 1] = static_cast<uint8_t>(diff >> 24);
82   } else {
83     // instr reg(s), offset_low
84     (*code)[literal_offset + 0] = static_cast<uint8_t>(diff >> 0);
85     (*code)[literal_offset + 1] = static_cast<uint8_t>(diff >> 8);
86   }
87 }
88 
PatchBakerReadBarrierBranch(std::vector<uint8_t> * code ATTRIBUTE_UNUSED,const LinkerPatch & patch ATTRIBUTE_UNUSED,uint32_t patch_offset ATTRIBUTE_UNUSED)89 void MipsRelativePatcher::PatchBakerReadBarrierBranch(std::vector<uint8_t>* code ATTRIBUTE_UNUSED,
90                                                       const LinkerPatch& patch ATTRIBUTE_UNUSED,
91                                                       uint32_t patch_offset ATTRIBUTE_UNUSED) {
92   LOG(FATAL) << "UNIMPLEMENTED";
93 }
94 
GenerateThunkDebugInfo(uint32_t executable_offset ATTRIBUTE_UNUSED)95 std::vector<debug::MethodDebugInfo> MipsRelativePatcher::GenerateThunkDebugInfo(
96     uint32_t executable_offset ATTRIBUTE_UNUSED) {
97   return std::vector<debug::MethodDebugInfo>();  // No thunks added.
98 }
99 
100 }  // namespace linker
101 }  // namespace art
102