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
15namespace v8 {
16namespace internal {
17namespace 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.
24struct CodeProtectionInfo {
25 Address base;
26 size_t size;
27 size_t num_protected_instructions;
28 ProtectedInstructionData instructions[1];
29};
30
31class 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.
51struct CodeProtectionInfoListEntry {
52 CodeProtectionInfo* code_info;
53 size_t next_free;
54};
55
56extern size_t gNumCodeObjects;
57extern CodeProtectionInfoListEntry* gCodeObjects;
58
59extern 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.
65bool 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