1//===-- tsd.h ---------------------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef SCUDO_TSD_H_
10#define SCUDO_TSD_H_
11
12#include "atomic_helpers.h"
13#include "common.h"
14#include "mutex.h"
15#include "thread_annotations.h"
16
17#include <limits.h> // for PTHREAD_DESTRUCTOR_ITERATIONS
18#include <pthread.h>
19
20// With some build setups, this might still not be defined.
21#ifndef PTHREAD_DESTRUCTOR_ITERATIONS
22#define PTHREAD_DESTRUCTOR_ITERATIONS 4
23#endif
24
25namespace scudo {
26
27template <class Allocator> struct alignas(SCUDO_CACHE_LINE_SIZE) TSD {
28 using ThisT = TSD<Allocator>;
29 u8 DestructorIterations = 0;
30
31 void init(Allocator *Instance) NO_THREAD_SAFETY_ANALYSIS {
32 DCHECK_EQ(DestructorIterations, 0U);
33 DCHECK(isAligned(reinterpret_cast<uptr>(this), alignof(ThisT)));
34 Instance->initCache(&Cache);
35 DestructorIterations = PTHREAD_DESTRUCTOR_ITERATIONS;
36 }
37
38 inline bool tryLock() NO_THREAD_SAFETY_ANALYSIS {
39 if (Mutex.tryLock()) {
40 atomic_store_relaxed(A: &Precedence, V: 0);
41 return true;
42 }
43 if (atomic_load_relaxed(A: &Precedence) == 0)
44 atomic_store_relaxed(
45 A: &Precedence,
46 V: static_cast<uptr>(getMonotonicTime() >> FIRST_32_SECOND_64(16, 0)));
47 return false;
48 }
49 inline void lock() NO_THREAD_SAFETY_ANALYSIS {
50 atomic_store_relaxed(A: &Precedence, V: 0);
51 Mutex.lock();
52 }
53 inline void unlock() NO_THREAD_SAFETY_ANALYSIS { Mutex.unlock(); }
54 inline uptr getPrecedence() { return atomic_load_relaxed(A: &Precedence); }
55
56 void commitBack(Allocator *Instance) { Instance->commitBack(this); }
57
58 // As the comments attached to `getCache()`, the TSD doesn't always need to be
59 // locked. In that case, we would only skip the check before we have all TSDs
60 // locked in all paths.
61 void assertLocked(bool BypassCheck) ASSERT_CAPABILITY(Mutex) {
62 if (SCUDO_DEBUG && !BypassCheck)
63 Mutex.assertHeld();
64 }
65
66 // Ideally, we may want to assert that all the operations on
67 // Cache/QuarantineCache always have the `Mutex` acquired. However, the
68 // current architecture of accessing TSD is not easy to cooperate with the
69 // thread-safety analysis because of pointer aliasing. So now we just add the
70 // assertion on the getters of Cache/QuarantineCache.
71 //
72 // TODO(chiahungduan): Ideally, we want to do `Mutex.assertHeld` but acquiring
73 // TSD doesn't always require holding the lock. Add this assertion while the
74 // lock is always acquired.
75 typename Allocator::CacheT &getCache() REQUIRES(Mutex) { return Cache; }
76 typename Allocator::QuarantineCacheT &getQuarantineCache() REQUIRES(Mutex) {
77 return QuarantineCache;
78 }
79
80private:
81 HybridMutex Mutex;
82 atomic_uptr Precedence = {};
83
84 typename Allocator::CacheT Cache GUARDED_BY(Mutex);
85 typename Allocator::QuarantineCacheT QuarantineCache GUARDED_BY(Mutex);
86};
87
88} // namespace scudo
89
90#endif // SCUDO_TSD_H_
91

source code of compiler-rt/lib/scudo/standalone/tsd.h