1 | // Copyright 2016 the V8 project authors. All rights reserved. |
2 | // Use of this source code is governed by a BSD-style license that can be |
3 | // found in the LICENSE file. |
4 | |
5 | #ifndef V8_TRAP_HANDLER_TRAP_HANDLER_INTERNAL_H_ |
6 | #define V8_TRAP_HANDLER_TRAP_HANDLER_INTERNAL_H_ |
7 | |
8 | // This file should not be included (even transitively) by files outside of |
9 | // src/trap-handler. |
10 | |
11 | #include "src/trap-handler/trap-handler.h" |
12 | |
13 | #include <atomic> |
14 | |
15 | namespace v8 { |
16 | namespace internal { |
17 | namespace trap_handler { |
18 | |
19 | // This describes a chunk of code that the trap handler will be able to handle |
20 | // faults in. {base} points to the beginning of the chunk, and {size} is the |
21 | // number of bytes in the code chunk. The remainder of the struct is a list of |
22 | // protected memory access instructions and an offset to a landing pad to handle |
23 | // faults on that instruction. |
24 | struct CodeProtectionInfo { |
25 | Address base; |
26 | size_t size; |
27 | size_t num_protected_instructions; |
28 | ProtectedInstructionData instructions[1]; |
29 | }; |
30 | |
31 | class MetadataLock { |
32 | static std::atomic_flag spinlock_; |
33 | |
34 | public: |
35 | MetadataLock(); |
36 | ~MetadataLock(); |
37 | |
38 | // We'd normally use DISALLOW_COPY_AND_ASSIGN, but we're avoiding a dependency |
39 | // on base/macros.h |
40 | MetadataLock(const MetadataLock&) = delete; |
41 | void operator=(const MetadataLock&) = delete; |
42 | }; |
43 | |
44 | // To enable constant time registration of handler data, we keep a free list of |
45 | // entries in the gCodeObjects table. Each entry contains a {next_free} field, |
46 | // which can be used to figure out where the next entry should be inserted. |
47 | // In order to avoid having to initialize all the links to start with, we use |
48 | // 0 to indicate that this is a fresh, never-used list entry and that therefore |
49 | // the next entry is known to be free. If {next_entry} is greater than zero, |
50 | // then {next_entry - 1} is the index that we should insert into next. |
51 | struct CodeProtectionInfoListEntry { |
52 | CodeProtectionInfo* code_info; |
53 | size_t next_free; |
54 | }; |
55 | |
56 | extern size_t gNumCodeObjects; |
57 | extern CodeProtectionInfoListEntry* gCodeObjects; |
58 | |
59 | extern std::atomic_size_t gRecoveredTrapCount; |
60 | |
61 | // Searches the fault location table for an entry matching fault_addr. If found, |
62 | // returns true and sets landing_pad to the address of a fragment of code that |
63 | // can recover from this fault. Otherwise, returns false and leaves offset |
64 | // unchanged. |
65 | bool TryFindLandingPad(uintptr_t fault_addr, uintptr_t* landing_pad); |
66 | |
67 | } // namespace trap_handler |
68 | } // namespace internal |
69 | } // namespace v8 |
70 | |
71 | #endif // V8_TRAP_HANDLER_TRAP_HANDLER_INTERNAL_H_ |
72 | |