1 /*
2  * Copyright (C) 2017 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_LINKER_PATCH_H_
18 #define ART_COMPILER_LINKER_LINKER_PATCH_H_
19 
20 #include <iosfwd>
21 #include <stdint.h>
22 
23 #include <android-base/logging.h>
24 
25 #include "base/bit_utils.h"
26 #include "dex/method_reference.h"
27 
28 namespace art {
29 
30 class DexFile;
31 
32 namespace linker {
33 
34 class LinkerPatch {
35  public:
36   // Note: We explicitly specify the underlying type of the enum because GCC
37   // would otherwise select a bigger underlying type and then complain that
38   //     'art::LinkerPatch::patch_type_' is too small to hold all
39   //     values of 'enum class art::LinkerPatch::Type'
40   // which is ridiculous given we have only a handful of values here. If we
41   // choose to squeeze the Type into fewer than 8 bits, we'll have to declare
42   // patch_type_ as an uintN_t and do explicit static_cast<>s.
43   enum class Type : uint8_t {
44     kMethodRelative,          // NOTE: Actual patching is instruction_set-dependent.
45     kMethodBssEntry,          // NOTE: Actual patching is instruction_set-dependent.
46     kCall,
47     kCallRelative,            // NOTE: Actual patching is instruction_set-dependent.
48     kTypeRelative,            // NOTE: Actual patching is instruction_set-dependent.
49     kTypeClassTable,          // NOTE: Actual patching is instruction_set-dependent.
50     kTypeBssEntry,            // NOTE: Actual patching is instruction_set-dependent.
51     kStringRelative,          // NOTE: Actual patching is instruction_set-dependent.
52     kStringInternTable,       // NOTE: Actual patching is instruction_set-dependent.
53     kStringBssEntry,          // NOTE: Actual patching is instruction_set-dependent.
54     kBakerReadBarrierBranch,  // NOTE: Actual patching is instruction_set-dependent.
55   };
56 
RelativeMethodPatch(size_t literal_offset,const DexFile * target_dex_file,uint32_t pc_insn_offset,uint32_t target_method_idx)57   static LinkerPatch RelativeMethodPatch(size_t literal_offset,
58                                          const DexFile* target_dex_file,
59                                          uint32_t pc_insn_offset,
60                                          uint32_t target_method_idx) {
61     LinkerPatch patch(literal_offset, Type::kMethodRelative, target_dex_file);
62     patch.method_idx_ = target_method_idx;
63     patch.pc_insn_offset_ = pc_insn_offset;
64     return patch;
65   }
66 
MethodBssEntryPatch(size_t literal_offset,const DexFile * target_dex_file,uint32_t pc_insn_offset,uint32_t target_method_idx)67   static LinkerPatch MethodBssEntryPatch(size_t literal_offset,
68                                          const DexFile* target_dex_file,
69                                          uint32_t pc_insn_offset,
70                                          uint32_t target_method_idx) {
71     LinkerPatch patch(literal_offset, Type::kMethodBssEntry, target_dex_file);
72     patch.method_idx_ = target_method_idx;
73     patch.pc_insn_offset_ = pc_insn_offset;
74     return patch;
75   }
76 
CodePatch(size_t literal_offset,const DexFile * target_dex_file,uint32_t target_method_idx)77   static LinkerPatch CodePatch(size_t literal_offset,
78                                const DexFile* target_dex_file,
79                                uint32_t target_method_idx) {
80     LinkerPatch patch(literal_offset, Type::kCall, target_dex_file);
81     patch.method_idx_ = target_method_idx;
82     return patch;
83   }
84 
RelativeCodePatch(size_t literal_offset,const DexFile * target_dex_file,uint32_t target_method_idx)85   static LinkerPatch RelativeCodePatch(size_t literal_offset,
86                                        const DexFile* target_dex_file,
87                                        uint32_t target_method_idx) {
88     LinkerPatch patch(literal_offset, Type::kCallRelative, target_dex_file);
89     patch.method_idx_ = target_method_idx;
90     return patch;
91   }
92 
RelativeTypePatch(size_t literal_offset,const DexFile * target_dex_file,uint32_t pc_insn_offset,uint32_t target_type_idx)93   static LinkerPatch RelativeTypePatch(size_t literal_offset,
94                                        const DexFile* target_dex_file,
95                                        uint32_t pc_insn_offset,
96                                        uint32_t target_type_idx) {
97     LinkerPatch patch(literal_offset, Type::kTypeRelative, target_dex_file);
98     patch.type_idx_ = target_type_idx;
99     patch.pc_insn_offset_ = pc_insn_offset;
100     return patch;
101   }
102 
TypeClassTablePatch(size_t literal_offset,const DexFile * target_dex_file,uint32_t pc_insn_offset,uint32_t target_type_idx)103   static LinkerPatch TypeClassTablePatch(size_t literal_offset,
104                                          const DexFile* target_dex_file,
105                                          uint32_t pc_insn_offset,
106                                          uint32_t target_type_idx) {
107     LinkerPatch patch(literal_offset, Type::kTypeClassTable, target_dex_file);
108     patch.type_idx_ = target_type_idx;
109     patch.pc_insn_offset_ = pc_insn_offset;
110     return patch;
111   }
112 
TypeBssEntryPatch(size_t literal_offset,const DexFile * target_dex_file,uint32_t pc_insn_offset,uint32_t target_type_idx)113   static LinkerPatch TypeBssEntryPatch(size_t literal_offset,
114                                        const DexFile* target_dex_file,
115                                        uint32_t pc_insn_offset,
116                                        uint32_t target_type_idx) {
117     LinkerPatch patch(literal_offset, Type::kTypeBssEntry, target_dex_file);
118     patch.type_idx_ = target_type_idx;
119     patch.pc_insn_offset_ = pc_insn_offset;
120     return patch;
121   }
122 
RelativeStringPatch(size_t literal_offset,const DexFile * target_dex_file,uint32_t pc_insn_offset,uint32_t target_string_idx)123   static LinkerPatch RelativeStringPatch(size_t literal_offset,
124                                          const DexFile* target_dex_file,
125                                          uint32_t pc_insn_offset,
126                                          uint32_t target_string_idx) {
127     LinkerPatch patch(literal_offset, Type::kStringRelative, target_dex_file);
128     patch.string_idx_ = target_string_idx;
129     patch.pc_insn_offset_ = pc_insn_offset;
130     return patch;
131   }
132 
StringInternTablePatch(size_t literal_offset,const DexFile * target_dex_file,uint32_t pc_insn_offset,uint32_t target_string_idx)133   static LinkerPatch StringInternTablePatch(size_t literal_offset,
134                                             const DexFile* target_dex_file,
135                                             uint32_t pc_insn_offset,
136                                             uint32_t target_string_idx) {
137     LinkerPatch patch(literal_offset, Type::kStringInternTable, target_dex_file);
138     patch.string_idx_ = target_string_idx;
139     patch.pc_insn_offset_ = pc_insn_offset;
140     return patch;
141   }
142 
StringBssEntryPatch(size_t literal_offset,const DexFile * target_dex_file,uint32_t pc_insn_offset,uint32_t target_string_idx)143   static LinkerPatch StringBssEntryPatch(size_t literal_offset,
144                                          const DexFile* target_dex_file,
145                                          uint32_t pc_insn_offset,
146                                          uint32_t target_string_idx) {
147     LinkerPatch patch(literal_offset, Type::kStringBssEntry, target_dex_file);
148     patch.string_idx_ = target_string_idx;
149     patch.pc_insn_offset_ = pc_insn_offset;
150     return patch;
151   }
152 
153   static LinkerPatch BakerReadBarrierBranchPatch(size_t literal_offset,
154                                                  uint32_t custom_value1 = 0u,
155                                                  uint32_t custom_value2 = 0u) {
156     LinkerPatch patch(literal_offset, Type::kBakerReadBarrierBranch, nullptr);
157     patch.baker_custom_value1_ = custom_value1;
158     patch.baker_custom_value2_ = custom_value2;
159     return patch;
160   }
161 
162   LinkerPatch(const LinkerPatch& other) = default;
163   LinkerPatch& operator=(const LinkerPatch& other) = default;
164 
LiteralOffset()165   size_t LiteralOffset() const {
166     return literal_offset_;
167   }
168 
GetType()169   Type GetType() const {
170     return patch_type_;
171   }
172 
IsPcRelative()173   bool IsPcRelative() const {
174     switch (GetType()) {
175       case Type::kMethodRelative:
176       case Type::kMethodBssEntry:
177       case Type::kCallRelative:
178       case Type::kTypeRelative:
179       case Type::kTypeClassTable:
180       case Type::kTypeBssEntry:
181       case Type::kStringRelative:
182       case Type::kStringInternTable:
183       case Type::kStringBssEntry:
184       case Type::kBakerReadBarrierBranch:
185         return true;
186       default:
187         return false;
188     }
189   }
190 
TargetMethod()191   MethodReference TargetMethod() const {
192     DCHECK(patch_type_ == Type::kMethodRelative ||
193            patch_type_ == Type::kMethodBssEntry ||
194            patch_type_ == Type::kCall ||
195            patch_type_ == Type::kCallRelative);
196     return MethodReference(target_dex_file_, method_idx_);
197   }
198 
TargetTypeDexFile()199   const DexFile* TargetTypeDexFile() const {
200     DCHECK(patch_type_ == Type::kTypeRelative ||
201            patch_type_ == Type::kTypeClassTable ||
202            patch_type_ == Type::kTypeBssEntry);
203     return target_dex_file_;
204   }
205 
TargetTypeIndex()206   dex::TypeIndex TargetTypeIndex() const {
207     DCHECK(patch_type_ == Type::kTypeRelative ||
208            patch_type_ == Type::kTypeClassTable ||
209            patch_type_ == Type::kTypeBssEntry);
210     return dex::TypeIndex(type_idx_);
211   }
212 
TargetStringDexFile()213   const DexFile* TargetStringDexFile() const {
214     DCHECK(patch_type_ == Type::kStringRelative ||
215            patch_type_ == Type::kStringInternTable ||
216            patch_type_ == Type::kStringBssEntry);
217     return target_dex_file_;
218   }
219 
TargetStringIndex()220   dex::StringIndex TargetStringIndex() const {
221     DCHECK(patch_type_ == Type::kStringRelative ||
222            patch_type_ == Type::kStringInternTable ||
223            patch_type_ == Type::kStringBssEntry);
224     return dex::StringIndex(string_idx_);
225   }
226 
PcInsnOffset()227   uint32_t PcInsnOffset() const {
228     DCHECK(patch_type_ == Type::kMethodRelative ||
229            patch_type_ == Type::kMethodBssEntry ||
230            patch_type_ == Type::kTypeRelative ||
231            patch_type_ == Type::kTypeClassTable ||
232            patch_type_ == Type::kTypeBssEntry ||
233            patch_type_ == Type::kStringRelative ||
234            patch_type_ == Type::kStringInternTable ||
235            patch_type_ == Type::kStringBssEntry);
236     return pc_insn_offset_;
237   }
238 
GetBakerCustomValue1()239   uint32_t GetBakerCustomValue1() const {
240     DCHECK(patch_type_ == Type::kBakerReadBarrierBranch);
241     return baker_custom_value1_;
242   }
243 
GetBakerCustomValue2()244   uint32_t GetBakerCustomValue2() const {
245     DCHECK(patch_type_ == Type::kBakerReadBarrierBranch);
246     return baker_custom_value2_;
247   }
248 
249  private:
LinkerPatch(size_t literal_offset,Type patch_type,const DexFile * target_dex_file)250   LinkerPatch(size_t literal_offset, Type patch_type, const DexFile* target_dex_file)
251       : target_dex_file_(target_dex_file),
252         literal_offset_(literal_offset),
253         patch_type_(patch_type) {
254     cmp1_ = 0u;
255     cmp2_ = 0u;
256     // The compiler rejects methods that are too big, so the compiled code
257     // of a single method really shouln't be anywhere close to 16MiB.
258     DCHECK(IsUint<24>(literal_offset));
259   }
260 
261   const DexFile* target_dex_file_;
262   // TODO: Clean up naming. Some patched locations are literals but others are not.
263   uint32_t literal_offset_ : 24;  // Method code size up to 16MiB.
264   Type patch_type_ : 8;
265   union {
266     uint32_t cmp1_;             // Used for relational operators.
267     uint32_t method_idx_;       // Method index for Call/Method patches.
268     uint32_t type_idx_;         // Type index for Type patches.
269     uint32_t string_idx_;       // String index for String patches.
270     uint32_t baker_custom_value1_;
271     static_assert(sizeof(method_idx_) == sizeof(cmp1_), "needed by relational operators");
272     static_assert(sizeof(type_idx_) == sizeof(cmp1_), "needed by relational operators");
273     static_assert(sizeof(string_idx_) == sizeof(cmp1_), "needed by relational operators");
274     static_assert(sizeof(baker_custom_value1_) == sizeof(cmp1_), "needed by relational operators");
275   };
276   union {
277     // Note: To avoid uninitialized padding on 64-bit systems, we use `size_t` for `cmp2_`.
278     // This allows a hashing function to treat an array of linker patches as raw memory.
279     size_t cmp2_;             // Used for relational operators.
280     // Literal offset of the insn loading PC (same as literal_offset if it's the same insn,
281     // may be different if the PC-relative addressing needs multiple insns).
282     uint32_t pc_insn_offset_;
283     uint32_t baker_custom_value2_;
284     static_assert(sizeof(pc_insn_offset_) <= sizeof(cmp2_), "needed by relational operators");
285     static_assert(sizeof(baker_custom_value2_) <= sizeof(cmp2_), "needed by relational operators");
286   };
287 
288   friend bool operator==(const LinkerPatch& lhs, const LinkerPatch& rhs);
289   friend bool operator<(const LinkerPatch& lhs, const LinkerPatch& rhs);
290 };
291 std::ostream& operator<<(std::ostream& os, const LinkerPatch::Type& type);
292 
293 inline bool operator==(const LinkerPatch& lhs, const LinkerPatch& rhs) {
294   return lhs.literal_offset_ == rhs.literal_offset_ &&
295       lhs.patch_type_ == rhs.patch_type_ &&
296       lhs.target_dex_file_ == rhs.target_dex_file_ &&
297       lhs.cmp1_ == rhs.cmp1_ &&
298       lhs.cmp2_ == rhs.cmp2_;
299 }
300 
301 inline bool operator<(const LinkerPatch& lhs, const LinkerPatch& rhs) {
302   return (lhs.literal_offset_ != rhs.literal_offset_) ? lhs.literal_offset_ < rhs.literal_offset_
303       : (lhs.patch_type_ != rhs.patch_type_) ? lhs.patch_type_ < rhs.patch_type_
304       : (lhs.target_dex_file_ != rhs.target_dex_file_) ? lhs.target_dex_file_ < rhs.target_dex_file_
305       : (lhs.cmp1_ != rhs.cmp1_) ? lhs.cmp1_ < rhs.cmp1_
306       : lhs.cmp2_ < rhs.cmp2_;
307 }
308 
309 }  // namespace linker
310 }  // namespace art
311 
312 #endif  // ART_COMPILER_LINKER_LINKER_PATCH_H_
313